Detailed Explanation of the Formulation Characteristics of Creep Feed for Suckling Piglets and Key Points for Raw Material Selection
A Discussion on the Formulation Characteristics of Creep Feed for Suckling Piglets and Key Points for Raw Material Selection (Reprinted)
This article is reprinted from the China Feed Industry Information Network. The web address of the article is: http://www.feedtrade.com.cn/tech/PIONEER/200806/206751.html
Based on the current research, production and application status of commercial pig feed in China, and from the perspective of feed cost-effectiveness, lactating sow feed and creep feed for suckling piglets are the two types of feed that are not easy to get right, and are also the most difficult to do well.
In China, pigs weighing less than 15 kg are customarily called suckling piglets, and the feed used during this stage is called creep feed for suckling piglets. With the improvement of pig-raising standards, the accelerated development of the feed industry and the rapid growth of large-scale pig farms, the market in developed pig-raising areas has subdivided creep feed for suckling piglets into two stages, namely high-grade creep feed (also known as creep feed for early weaning, or "jiaocao liao") and general creep feed. It is generally accepted in the industry that "jiaocao liao" refers to the feed used from 5 days after birth when supplementary feeding begins until 10 days after weaning; general creep feed refers to the feed used from 10 days after weaning until the piglet reaches 15 kg.
At present, some practical problems have also emerged in the use of creep feed for suckling piglets. (1) After switching from "jiaocao liao" to general creep feed, within one week piglets will show reduced feed intake, growth stagnation and increased diarrhea. We need to handle the transition between general creep feed and high-grade creep feed properly, and should not make the grade gap between general creep feed and high-grade creep feed too large. (2) Many high-grade creep feeds have solved the problems of diarrhea, weak piglets and feed intake, but the growth rate is not ideal enough, and the feed conversion ratio is also not ideal enough, so the cost of weight gain is very high; (3) Because many "jiaocao liao" products use high doses of drug additives to control diarrhea, when piglets stop using "jiaocao liao" and switch to general creep feed or even to starter feed, their growth rate is relatively slow, which makes the advantages of "jiaocao liao" almost completely disappear! This also requires great attention.
At present, the standards for a good, satisfactory "jiaocao liao" should be: (1) Under normal feeding conditions, for normal lean-type piglets weaned at 21 days, 3 days after weaning, feed intake and growth rate should recover to the levels before weaning; (2) From the day of weaning, within 10 days, the nutritional diarrhea rate should be below 21%, the feed conversion ratio should be around 1.2, the average daily gain should be around 280 g, and the average daily feed intake should be around 330 g; (3) Based on current raw material costs, the feed cost should not exceed 5500 yuan/ton. The standards for a good, satisfactory general creep feed product should be: After following "jiaocao liao", feed intake continues to increase, growth rate continues to increase, and the diarrhea rate does not increase; by 42 days of age, body weight reaches 15 kg, and the feed conversion ratio is around 1.5; based on current raw material costs, the feed cost should not exceed 4500 yuan/ton. Below we will discuss our views from the aspects of the nutritional requirements characteristics of suckling piglets, formulation characteristics, raw material selection, quality control and processing key points.
1 Nutritional Requirement Characteristics of Suckling Piglets
The birth weight of piglets is about 1.4 kg (slightly different among breeds). After birth, they grow and develop rapidly, and this is the period of greatest growth intensity, with high feed conversion efficiency. If growth and development are hindered at this stage, it is easy to form stunted pigs. Due to rapid growth and development, the demand for nutrients is high, especially the metabolism of protein, calcium, phosphorus and iron is much higher than that of adult pigs. They are sensitive to nutritionally incomplete feed. Studies have shown that the growth performance in the first week after weaning will have an important impact on the growth performance throughout the pig's life. Therefore, for piglets in the first week after weaning, in addition to strengthening feeding management, an important factor is to improve the quality of the feed for weaned piglets. Below is a brief discussion of the nutritional requirement characteristics of suckling piglets.
1.1 Energy Requirements
The ultimate goal of raising suckling piglets is to obtain the maximum weaning weight and improve herd uniformity. Research results show that piglets with larger weaning weight transition smoothly to the post-weaning diet and reduce the incidence of nutritional diarrhea; piglets that grow faster during the suckling period also grow faster during the growing-finishing period. Pollmann pointed out that piglets gaining about 900 g in the first week after weaning are marketed 15 days earlier than piglets that gain no weight; research by Tokach et al. (1992) also showed that piglets gaining more than 225 g/d in the first week after weaning at 21 days of age can reach 109 kg body weight 10 days earlier.
Protein deposition in suckling piglets is positively correlated with energy intake. Therefore, to obtain the maximum protein deposition rate, it is necessary to provide the maximum energy intake for suckling piglets. Considering the need to meet the nutritional needs of weak piglets as much as possible, the energy design of creep feed for suckling piglets should not be too high, so as to increase the feed intake of weak piglets.
After birth, protein and fat deposition in piglets increases rapidly. From birth to weaning at 21 days of age, the protein and fat content of piglets increases linearly, with average growth rates of 25-38 g/d and 25-35 g/d, respectively. During the transition from suckling to weaning, due to the impact of weaning stress, protein growth slows down, while fat growth is usually negative. During this period, the rate of protein deposition is related both to feed intake and to the content of available protein in the feed. Under good thermal insulation conditions, the rate of body fat mobilization is closely related to feed intake and the content of available protein in the diet.
According to relevant data from the United States, the maintenance metabolizable energy requirement of suckling piglets is 470 kJ/kg·BW0.75·d, the maintenance metabolizable energy requirement of piglets in the first week after weaning (4 weeks of age) is 453 kJ/kg·BW0.75·d, and in the second week it is 423 kJ/kg·BW0.75·d. The maintenance metabolizable energy requirement of piglets is also related to environmental temperature. When the environmental temperature is 1°C below the critical temperature, the metabolizable energy requirement increases by 2%-5%.
Newborn piglets already contain a relatively high amount of pancreatic lipase, but before 3 weeks of age, bile secretion is low and cannot activate pancreatic lipase or emulsify feed fat. At this time, the ability of piglets to digest fat is limited. Until 16 days of age, the stomach of piglets can only digest 25%-50% of feed fat. Fat in sow's milk exists in an emulsified state, so its fat utilization rate is relatively high. It is reported that the apparent digestibility of fat in sow's milk by piglets is about 95%. After 3 weeks of age, as bile secretion gradually increases, the digestion and absorption of feed fat gradually strengthens. In weaned piglets, the efficiencies of metabolizable energy intake used for growth, protein energy deposition and fat energy deposition are 0.72, 0.66 and 0.77, respectively, close to the corresponding values for growing pigs.
1.2 Protein and Amino Acid Requirements
Piglets grow rapidly after birth and undergo drastic physiological changes, so their nutritional requirements for protein and amino acids are high. However, the digestive system of piglets is not fully developed. For example, the trypsin content of piglets remains at a relatively low level before 5 weeks of age and only begins to increase at 6 weeks of age. Therefore, before 5 weeks of age, piglets have limited ability to digest and absorb feed protein, especially plant protein. After weaning, the nutrient source changes from sow's milk to solid feed. High protein levels in the diet often lead to diarrhea and growth inhibition in piglets, so determining the appropriate protein level in piglet diets is particularly important. Based on relevant research reports, a crude protein level of 19%-21% can meet the needs of 4-20 kg piglets. It is recommended to use 21% for the 4-10 kg stage and 19% for the 10-20 kg stage.
The amino acid requirements of piglets are one of the key research areas at home and abroad. The amino acid requirements of growing pigs are divided into maintenance requirements and protein deposition requirements, and the ideal amino acid ratios for maintenance and protein deposition are different. Because the proportion of amino acids required for maintenance in piglets differs from that in growing pigs, the amino acid composition of body tissue protein differs at different stages, and piglets, especially weaned piglets, have special requirements for certain amino acids for immunity, antioxidant capacity, anti-stress and maintenance of intestinal function, the ideal amino acid pattern for piglets differs from that for growing-finishing pigs. Practice has shown that the requirements for some amino acids are indeed different, such as glutamic acid, threonine and histidine. These all await further exploration, and in application, the ideal protein pattern can be referred to for flexible control.
1.3 Mineral Requirements and Vitamin Requirements
Weaned piglets respond positively to added salt, so NRC increased the sodium and chlorine requirements of piglets. Potassium, sodium and chlorine in the diet interact with each other, and electrolyte balance should be considered, especially because creep feed for suckling piglets often has a relatively high potassium content. Relevant research reports indicate that the suitable electrolyte balance value for piglets is 200-300 meq/kg.
Although different studies have found relatively large differences in the requirements for copper, iron, zinc and manganese, the actual requirements may be close. Possible reasons for the analysis: (1) Different breeds may cause slight differences; (2) The absorption and utilization of trace elements in the animal body affect each other, and the levels of other trace elements in the basal diets designed by different researchers differ, affecting the research results on the requirements of the target element; (3) Some studies used too few experimental animals, and the requirements obtained by evaluating only growth performance are not accurate; (4) Some experimental designs had too few gradients, affecting the precision of the results; (5) Different environments and different stress conditions of pigs may lead to slightly different requirements. Trace elements not only affect the growth of piglets, but also involve safety and environmental protection issues. In particular, current piglet feed generally uses high copper and high zinc, and their trace element contents are generally higher than the nutritional requirements of piglets. Further in-depth research on the requirements and proportions of copper, iron, zinc and manganese for piglets remains important.
The role of high doses of copper and zinc in promoting piglet performance has been confirmed by a large number of studies, but the residue and pollution problems caused by high copper and high zinc should be taken seriously. A series of studies have shown that the use of organic chelates can reduce the amount of copper and zinc used and achieve the effects of high-dose copper sulfate and zinc oxide. However, this may not necessarily be achieved in actual production, thus creating a contradiction between some production costs and environmental pollution, and new approaches should be developed.
For many years, foreign countries have carried out a large amount of research on the vitamin requirements of pigs. NRC's recommended amounts for vitamins are based on the minimum requirements to prevent deficiency symptoms, without considering the needs for rapid growth, weaning, immunity and stress, which are very critical for raising piglets. Research results over the past decade show that: (1) NRC's recommended amounts of fat-soluble vitamins can meet the needs of normal growth of piglets, but to obtain optimal immune function and antioxidant capacity, 2-5 times the NRC requirement is needed. (2) To meet the needs of optimal growth of piglets, twice the NRC-recommended amount of water-soluble vitamins is necessary, and under special circumstances even higher amounts are needed. In fact, the amount of vitamins added in most feed in China has long been far higher than the NRC standard, so there are relatively few problems in this regard.
2 Feed Formulation Technology and Key Points for Raw Material Selection
We should formulate creep feed for suckling piglets according to their nutritional requirement characteristics, and master the formulation technology and characteristics of creep feed for suckling piglets. When selecting some raw materials, the principles to consider are: stable supply, guaranteed quality and moderate price. For example, for small peptide products, their quality is not very stable, so caution is needed when selecting them.
2.1 Key Points for Selecting Energy Feed
2.1.1 Corn is the first-choice raw material. Corn quality requirements are a test weight above 700, no mold, and few broken kernels. It is best to use about 50% (of the corn used) extruded corn, but not too much, otherwise pigs are prone to sticky mouths (for pellet feed), which then affects palatability. There is currently no standard for extruded corn. Personal experience suggests that an extrusion degree of gelatinization of 88% or above is sufficient. The corn crushing particle size can be 2.0 (preferably no more than 20% below 1.0). Secondly, some wheat can be selected, with a usage amount not exceeding 10%, and no additional wheat enzyme preparation is needed.
2.1.2 Whey powder, lactose and sucrose. Whey powder, lactose and sucrose are also high-quality energy sources for creep feed for suckling piglets. Using whey powder is essentially using lactose, so lactose content is very important. Among these, the role of milk-derived protein is good, but it is not as important as lactose. Sucrose can not only provide energy, but also improve palatability. Suckling piglets have a preference for sucrose, and its effect is better than saccharin sodium products. When using these raw materials, they must be conditioned and mixed evenly. These raw materials are heat-sensitive and prone to caramelization, and caramelization has a negative effect on pig palatability.
2.1.3 Oils and fats. At present, oils and fats are used in creep feed for suckling piglets. For suckling piglets, the best oil is coconut oil, followed by soybean oil, corn oil, lard, tallow and fish oil. Coconut oil is very expensive, and soybean oil is a more practical choice. After using a certain amount of extruded soybeans, oils and fats may not be needed. When using oils and fats, attention must be paid to quality. Impurities, moisture, iodine value, acid value and peroxide value are indicators that must be measured.
2.2 Key Points for Selecting Protein Feed
In the process of selecting protein raw materials for creep feed for suckling piglets, digestibility is the first criterion for selecting protein raw materials, followed by good amino acid ratio and content. The key amino acids considered include lysine, sulfur-containing amino acids, threonine, tryptophan and histidine. Therefore, when selecting protein raw materials, it is best to choose raw materials with relatively high contents of the above amino acids and a reasonable ratio. At the same time, due to the limited feed intake of suckling piglets, it is necessary to try to find protein raw materials with high nutrient content to save space. Under the premise of limited feed intake, provide suckling piglets with diets of high nutrient concentration and good digestibility as much as possible, so as to ensure that they obtain ideal daily gain during the piglet stage as much as possible and lay the foundation for overall profitability.
2.2.1 Soybean products. Soybean products are currently the most abundant protein source. However, due to different processing techniques, there are many options for soybean product protein in suckling piglet and piglet feed: (1) Extruded soybeans are not only a source of soybean oil, but also a source of high-quality soybean protein, but the amount of extruded soybeans used should not be too much, generally not more than 15%. At present, there is no standard for extruded soybeans. Personally, I believe that if urease is below 0.05 and digestible protein is above 60%, it can be used; (2) Soybean meal is a plant protein, and its digestibility often cannot meet the requirements of suckling piglets. It also contains certain anti-nutritional factors, but it is a commonly used and suitable protein source for creep feed for suckling piglets; (3) Soy protein isolate, although its protein content is relatively high, because it is made from low-temperature soybean meal, may also contain a certain amount of anti-nutritional factors, so it can be enzymatically degraded during processing; however, because some products produce bitter peptides after enzymatic degradation, which affects palatability, when selecting, on the one hand it should have good solubility, and on the other hand it should also ensure good palatability. From the current application effect, it is very good, but the price is relatively high; (4) Soy protein concentrate. Soybean meal is soaked and dissolved in hot alcohol, removing part of the polysaccharides, which is equivalent to concentrating the protein, so its value is higher than ordinary soybean meal, but its digestibility is still limited; (5) Fermented soybean meal. After fermentation of soybean meal, digestibility is greatly improved, protein content is also somewhat increased, and anti-nutritional factors are destroyed. Therefore, fermented soybean meal may be the first-choice raw material for future suckling piglet and piglet feed. However, because different manufacturers use different fermentation strains and processes, the value for suckling piglet and piglet feed varies greatly, so caution is also needed when using it. At present, the amount of fermented soybean meal in creep feed for suckling piglets should not be too much, otherwise there will be negative effects.
2.2.2 Milk-derived protein. Generally, the main protein sources used as feed protein are high-protein whey powder and whey protein concentrate WPC-34. Their digestibility and amino acid composition are second only to plasma protein powder. If calculated purely by protein content, their price is not lower than plasma protein powder. They are now mostly used for human consumption, and the supply is relatively limited, so they cannot be used in large quantities in feed.
2.2.3 Plasma protein powder. Plasma protein powder has advantages in digestibility and absorption rate, amino acid composition and the speed of producing small peptides through degradation, and is a high-quality protein raw material for suckling piglets. Especially for homologous plasma protein powder, because it itself contains abundant small peptides and its amino acid composition is close to that of pigs, the effect is better. However, due to the possibility of homologous diseases, the use of this type of raw material should be cautious. In addition, its high price and unstable supply also limit the normalization of its use. If it needs to be used, the amount must reach 3% to have a significant effect, and it is best to choose the imported American product.
2.2.4 Intestinal mucosal protein (DPS). DPS is also a high-quality source of protein for suckling piglets, and it works very well when used together with plasma protein powder. DPS not only provides high-quality protein, but can also prevent weaning stress from damaging the intestinal mucosa of suckling piglets. Similarly, due to consideration of homologous diseases, caution is needed in use. At present, only the imported American product can be used, and its price is also relatively high. In addition, channels and supply are still limited.
2.2.5 Fish meal. Fish meal should be the high-quality protein raw material that everyone is most familiar with. When using it, freshness must be measured, the degree of adulteration identified, and physicochemical indicators tested. Because fish meal quality is really difficult to control, it is recommended not to use too much, preferably controlled below 2%.
2.2.6 Small peptide products. At present, many small peptide products are used in creep feed for suckling piglets, and they are also the hottest thing in the field of feed nutrition research recently. This type of product should belong to functional protein raw materials. Of course, there is still some time before mature and stable use, and it should be a high-quality protein source with very bright prospects in the future.
2.2.7 Other protein sources. For example, meat and bone meal, cottonseed meal, rapeseed meal, DDGS, etc. are still under research, and their usage should be strictly limited.
2.3 Key Points for Selecting Feed Additives
2.3.1 Drug additives. Under China's feeding environment, the use of medicinal additives in creep feed for suckling piglets is necessary. According to relevant regulations and announcements of China's Ministry of Agriculture, the currently selectable drug additives include virginiamycin, bacitracin zinc, colistin sulfate, nosiheptide, efrotomycin, enramycin, olaquindox, oxytetracycline, chlortetracycline, salinomycin, etc.
2.3.2 High copper and high zinc additives. When using high copper, do not use high zinc; conversely, when using high zinc, high copper is also not needed. In addition, high copper and high zinc have synergistic effects with drug additives. When using them, the doses of high copper and high zinc should not be too high. It is unnecessary and also likely to cause environmental pollution.
2.3.3 Enzyme preparations. Enzyme preparations are very good things, and research and application are continuing to deepen. Because the pelleting temperature of creep feed for suckling piglets will not be higher than 80°C, many enzyme preparations can be used. Years of application results show that the effect of compound enzymes is better than that of single enzyme preparations (except phytase).
3 Quality Control and Processing Key Points
Quality control and processing are extremely important work, but unfortunately many feed companies do not pay attention to them. A good creep feed formula for suckling piglets, with good raw materials, but without quality control and processing technology as a guarantee, still cannot produce a good creep feed product for suckling piglets. Only by closely combining the four aspects of formula, raw materials, quality control and processing can good products be produced. The six indicators implemented for national feed product formulation must be done by the feed mill's own laboratory. Some other key indicators also need to be sent to relevant units for testing on a regular basis. In fact, it does not cost much money or time, but can achieve very good results. For example, when using zinc sulfate produced in a certain place, whether its heavy metals exceed the standard can be determined by sending it for testing just once. It is only necessary to send it for testing again when changing the supply channel. The quality control department of CP Group is separated from the technical department and made independent, which is worth learning from.
To do a good job with creep feed for suckling piglets, it is best for one's own unit to be able to test important indicators such as starch gelatinization rate, soluble protein, fish meal freshness, peroxide value and some hygiene indicators such as Salmonella.
The quality control and processing of creep feed for suckling piglets are mostly the same as for other pig feed, with not much particularity. The only difference is that some heat-sensitive raw materials are used, so special attention must be paid to controlling pelleting temperature and conditioning time. Conditioning temperature has a great impact on starch gelatinization. It is reported that there is a negative correlation between conditioning temperature and gelatinization degree. The greater the temperature difference between the mash entering the pellet mill and the pellets leaving the mill, the higher the gelatinization degree.
Creep feed pellets for suckling piglets should not be made too hard, as being too hard seriously affects palatability. Looking at the entire feed processing process, apart from the feed formula, the processing techniques that affect feed pellet hardness include: raw material grinding technology, raw material extrusion and expansion technology, raw material mixing, water addition and oil spraying technology, steam pre-conditioning technology, die selection during the pelleting process, post-curing and post-spraying technology, and drying and cooling technology. Among these, especially the steam conditioning process, the conditioning effect directly affects the internal structure and appearance quality of the pellets. The longer the conditioning time, the higher the starch gelatinization degree, the denser the formed pellet structure, and the greater the hardness. Considering the physiological characteristics of the digestive tract of suckling piglets and feed digestibility, a higher starch gelatinization degree is required, so we need to appropriately reduce the hardness of creep feed for suckling piglets through other methods. Therefore, choosing a suitable compression ratio ring die is particularly important. Generally speaking, a pellet ring die compression ratio of 6-8 is sufficient. If a lot of extruded raw materials are used, a compression ratio of 3 is sufficient. The feed made in this way is crisp and loose, only with a slightly higher fines rate.
After extrusion, corn and soybeans are crushed, and particle size generally does not pose a problem. Other commonly used raw materials are mainly corn and soybean meal. The particle size after crushing has some influence on the digestion and absorption of suckling piglets. Generally speaking, suckling piglets and piglets have a stronger ability to chew feed than growing-finishing pigs. Whether corn or sorghum, whether crushed or extruded and broken, particle size has no effect on piglet growth rate. However, experiments have shown that when barley particle size is 635 microns, the growth rate is 5% higher than at 768 microns, and feed utilization is also improved, indicating that the effect of particle size on piglet production performance is also related to the type of raw material. The effect of particle size on the digestion and absorption of nutrients is also related to the interaction between the machine type and feed variety. Current research results show that, considering various factors comprehensively, a particle size of 400 microns to 600 microns is suitable.
If making mash feed, attention should be paid to mixing uniformity. Studies have shown that when the coefficient of variation of mixing uniformity of piglet feed decreases from 106.5% to 28.4%, the average daily gain increases by 41%, feed utilization increases by 18.52%, and feed intake increases by 18.33%. Therefore, the mixing time for weaned piglet feed should reach 4-6 min, and its coefficient of variation should be no more than 10% according to China's compound feed standard requirements, so as to ensure that the feed is fully mixed and nutrients are evenly distributed. Therefore, it is best to adopt a two-stage grinding process (after mixing evenly, grind once more). In this way, the product appearance is like that made from a single raw material, and it is also more uniform.
Recent studies have shown that the gelatinization rate of pellets has a huge impact on animal production performance. Data show that increasing the gelatinization rate by 5%-10% can improve animal production performance by 3%-5%, and the same effect also applies to creep feed for suckling piglets.
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Not bad, I learned something first, thanks to the original poster.
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Thank you. It took me 30 seconds to finish reading it quickly.
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This article is very well written. It has both a theoretical basis and practical accumulated content; but it is not complete enough. I rate it 95 points.
Based on the current research, production and application status of commercial pig feed in China, and from the perspective of feed cost-effectiveness, lactating sow feed and creep feed for suckling piglets are the two types of feed that are not easy to get right, and are also the most difficult to do well.
In China, pigs weighing less than 15 kg are customarily called suckling piglets, and the feed used during this stage is called creep feed for suckling piglets. With the improvement of pig-raising standards, the accelerated development of the feed industry and the rapid growth of large-scale pig farms, the market in developed pig-raising areas has subdivided creep feed for suckling piglets into two stages, namely high-grade creep feed (also known as creep feed for early weaning, or "jiaocao liao") and general creep feed. It is generally accepted in the industry that "jiaocao liao" refers to the feed used from 5 days after birth when supplementary feeding begins until 10 days after weaning; general creep feed refers to the feed used from 10 days after weaning until the piglet reaches 15 kg.
At present, some practical problems have also emerged in the use of creep feed for suckling piglets. (1) After switching from "jiaocao liao" to general creep feed, within one week piglets will show reduced feed intake, growth stagnation and increased diarrhea. We need to handle the transition between general creep feed and high-grade creep feed properly, and should not make the grade gap between general creep feed and high-grade creep feed too large. (2) Many high-grade creep feeds have solved the problems of diarrhea, weak piglets and feed intake, but the growth rate is not ideal enough, and the feed conversion ratio is also not ideal enough, so the cost of weight gain is very high; (3) Because many "jiaocao liao" products use high doses of drug additives to control diarrhea, when piglets stop using "jiaocao liao" and switch to general creep feed or even to starter feed, their growth rate is relatively slow, which makes the advantages of "jiaocao liao" almost completely disappear! This also requires great attention.
At present, the standards for a good, satisfactory "jiaocao liao" should be: (1) Under normal feeding conditions, for normal lean-type piglets weaned at 21 days, 3 days after weaning, feed intake and growth rate should recover to the levels before weaning; (2) From the day of weaning, within 10 days, the nutritional diarrhea rate should be below 21%, the feed conversion ratio should be around 1.2, the average daily gain should be around 280 g, and the average daily feed intake should be around 330 g; (3) Based on current raw material costs, the feed cost should not exceed 5500 yuan/ton. The standards for a good, satisfactory general creep feed product should be: After following "jiaocao liao", feed intake continues to increase, growth rate continues to increase, and the diarrhea rate does not increase; by 42 days of age, body weight reaches 15 kg, and the feed conversion ratio is around 1.5; based on current raw material costs, the feed cost should not exceed 4500 yuan/ton. Below we will discuss our views from the aspects of the nutritional requirements characteristics of suckling piglets, formulation characteristics, raw material selection, quality control and processing key points.
1 Nutritional Requirement Characteristics of Suckling Piglets
The birth weight of piglets is about 1.4 kg (slightly different among breeds). After birth, they grow and develop rapidly, and this is the period of greatest growth intensity, with high feed conversion efficiency. If growth and development are hindered at this stage, it is easy to form stunted pigs. Due to rapid growth and development, the demand for nutrients is high, especially the metabolism of protein, calcium, phosphorus and iron is much higher than that of adult pigs. They are sensitive to nutritionally incomplete feed. Studies have shown that the growth performance in the first week after weaning will have an important impact on the growth performance throughout the pig's life. Therefore, for piglets in the first week after weaning, in addition to strengthening feeding management, an important factor is to improve the quality of the feed for weaned piglets. Below is a brief discussion of the nutritional requirement characteristics of suckling piglets.
1.1 Energy Requirements
The ultimate goal of raising suckling piglets is to obtain the maximum weaning weight and improve herd uniformity. Research results show that piglets with larger weaning weight transition smoothly to the post-weaning diet and reduce the incidence of nutritional diarrhea; piglets that grow faster during the suckling period also grow faster during the growing-finishing period. Pollmann pointed out that piglets gaining about 900 g in the first week after weaning are marketed 15 days earlier than piglets that gain no weight; research by Tokach et al. (1992) also showed that piglets gaining more than 225 g/d in the first week after weaning at 21 days of age can reach 109 kg body weight 10 days earlier.
Protein deposition in suckling piglets is positively correlated with energy intake. Therefore, to obtain the maximum protein deposition rate, it is necessary to provide the maximum energy intake for suckling piglets. Considering the need to meet the nutritional needs of weak piglets as much as possible, the energy design of creep feed for suckling piglets should not be too high, so as to increase the feed intake of weak piglets.
After birth, protein and fat deposition in piglets increases rapidly. From birth to weaning at 21 days of age, the protein and fat content of piglets increases linearly, with average growth rates of 25-38 g/d and 25-35 g/d, respectively. During the transition from suckling to weaning, due to the impact of weaning stress, protein growth slows down, while fat growth is usually negative. During this period, the rate of protein deposition is related both to feed intake and to the content of available protein in the feed. Under good thermal insulation conditions, the rate of body fat mobilization is closely related to feed intake and the content of available protein in the diet.
According to relevant data from the United States, the maintenance metabolizable energy requirement of suckling piglets is 470 kJ/kg·BW0.75·d, the maintenance metabolizable energy requirement of piglets in the first week after weaning (4 weeks of age) is 453 kJ/kg·BW0.75·d, and in the second week it is 423 kJ/kg·BW0.75·d. The maintenance metabolizable energy requirement of piglets is also related to environmental temperature. When the environmental temperature is 1°C below the critical temperature, the metabolizable energy requirement increases by 2%-5%.
Newborn piglets already contain a relatively high amount of pancreatic lipase, but before 3 weeks of age, bile secretion is low and cannot activate pancreatic lipase or emulsify feed fat. At this time, the ability of piglets to digest fat is limited. Until 16 days of age, the stomach of piglets can only digest 25%-50% of feed fat. Fat in sow's milk exists in an emulsified state, so its fat utilization rate is relatively high. It is reported that the apparent digestibility of fat in sow's milk by piglets is about 95%. After 3 weeks of age, as bile secretion gradually increases, the digestion and absorption of feed fat gradually strengthens. In weaned piglets, the efficiencies of metabolizable energy intake used for growth, protein energy deposition and fat energy deposition are 0.72, 0.66 and 0.77, respectively, close to the corresponding values for growing pigs.
1.2 Protein and Amino Acid Requirements
Piglets grow rapidly after birth and undergo drastic physiological changes, so their nutritional requirements for protein and amino acids are high. However, the digestive system of piglets is not fully developed. For example, the trypsin content of piglets remains at a relatively low level before 5 weeks of age and only begins to increase at 6 weeks of age. Therefore, before 5 weeks of age, piglets have limited ability to digest and absorb feed protein, especially plant protein. After weaning, the nutrient source changes from sow's milk to solid feed. High protein levels in the diet often lead to diarrhea and growth inhibition in piglets, so determining the appropriate protein level in piglet diets is particularly important. Based on relevant research reports, a crude protein level of 19%-21% can meet the needs of 4-20 kg piglets. It is recommended to use 21% for the 4-10 kg stage and 19% for the 10-20 kg stage.
The amino acid requirements of piglets are one of the key research areas at home and abroad. The amino acid requirements of growing pigs are divided into maintenance requirements and protein deposition requirements, and the ideal amino acid ratios for maintenance and protein deposition are different. Because the proportion of amino acids required for maintenance in piglets differs from that in growing pigs, the amino acid composition of body tissue protein differs at different stages, and piglets, especially weaned piglets, have special requirements for certain amino acids for immunity, antioxidant capacity, anti-stress and maintenance of intestinal function, the ideal amino acid pattern for piglets differs from that for growing-finishing pigs. Practice has shown that the requirements for some amino acids are indeed different, such as glutamic acid, threonine and histidine. These all await further exploration, and in application, the ideal protein pattern can be referred to for flexible control.
1.3 Mineral Requirements and Vitamin Requirements
Weaned piglets respond positively to added salt, so NRC increased the sodium and chlorine requirements of piglets. Potassium, sodium and chlorine in the diet interact with each other, and electrolyte balance should be considered, especially because creep feed for suckling piglets often has a relatively high potassium content. Relevant research reports indicate that the suitable electrolyte balance value for piglets is 200-300 meq/kg.
Although different studies have found relatively large differences in the requirements for copper, iron, zinc and manganese, the actual requirements may be close. Possible reasons for the analysis: (1) Different breeds may cause slight differences; (2) The absorption and utilization of trace elements in the animal body affect each other, and the levels of other trace elements in the basal diets designed by different researchers differ, affecting the research results on the requirements of the target element; (3) Some studies used too few experimental animals, and the requirements obtained by evaluating only growth performance are not accurate; (4) Some experimental designs had too few gradients, affecting the precision of the results; (5) Different environments and different stress conditions of pigs may lead to slightly different requirements. Trace elements not only affect the growth of piglets, but also involve safety and environmental protection issues. In particular, current piglet feed generally uses high copper and high zinc, and their trace element contents are generally higher than the nutritional requirements of piglets. Further in-depth research on the requirements and proportions of copper, iron, zinc and manganese for piglets remains important.
The role of high doses of copper and zinc in promoting piglet performance has been confirmed by a large number of studies, but the residue and pollution problems caused by high copper and high zinc should be taken seriously. A series of studies have shown that the use of organic chelates can reduce the amount of copper and zinc used and achieve the effects of high-dose copper sulfate and zinc oxide. However, this may not necessarily be achieved in actual production, thus creating a contradiction between some production costs and environmental pollution, and new approaches should be developed.
For many years, foreign countries have carried out a large amount of research on the vitamin requirements of pigs. NRC's recommended amounts for vitamins are based on the minimum requirements to prevent deficiency symptoms, without considering the needs for rapid growth, weaning, immunity and stress, which are very critical for raising piglets. Research results over the past decade show that: (1) NRC's recommended amounts of fat-soluble vitamins can meet the needs of normal growth of piglets, but to obtain optimal immune function and antioxidant capacity, 2-5 times the NRC requirement is needed. (2) To meet the needs of optimal growth of piglets, twice the NRC-recommended amount of water-soluble vitamins is necessary, and under special circumstances even higher amounts are needed. In fact, the amount of vitamins added in most feed in China has long been far higher than the NRC standard, so there are relatively few problems in this regard.
2 Feed Formulation Technology and Key Points for Raw Material Selection
We should formulate creep feed for suckling piglets according to their nutritional requirement characteristics, and master the formulation technology and characteristics of creep feed for suckling piglets. When selecting some raw materials, the principles to consider are: stable supply, guaranteed quality and moderate price. For example, for small peptide products, their quality is not very stable, so caution is needed when selecting them.
2.1 Key Points for Selecting Energy Feed
2.1.1 Corn is the first-choice raw material. Corn quality requirements are a test weight above 700, no mold, and few broken kernels. It is best to use about 50% (of the corn used) extruded corn, but not too much, otherwise pigs are prone to sticky mouths (for pellet feed), which then affects palatability. There is currently no standard for extruded corn. Personal experience suggests that an extrusion degree of gelatinization of 88% or above is sufficient. The corn crushing particle size can be 2.0 (preferably no more than 20% below 1.0). Secondly, some wheat can be selected, with a usage amount not exceeding 10%, and no additional wheat enzyme preparation is needed.
2.1.2 Whey powder, lactose and sucrose. Whey powder, lactose and sucrose are also high-quality energy sources for creep feed for suckling piglets. Using whey powder is essentially using lactose, so lactose content is very important. Among these, the role of milk-derived protein is good, but it is not as important as lactose. Sucrose can not only provide energy, but also improve palatability. Suckling piglets have a preference for sucrose, and its effect is better than saccharin sodium products. When using these raw materials, they must be conditioned and mixed evenly. These raw materials are heat-sensitive and prone to caramelization, and caramelization has a negative effect on pig palatability.
2.1.3 Oils and fats. At present, oils and fats are used in creep feed for suckling piglets. For suckling piglets, the best oil is coconut oil, followed by soybean oil, corn oil, lard, tallow and fish oil. Coconut oil is very expensive, and soybean oil is a more practical choice. After using a certain amount of extruded soybeans, oils and fats may not be needed. When using oils and fats, attention must be paid to quality. Impurities, moisture, iodine value, acid value and peroxide value are indicators that must be measured.
2.2 Key Points for Selecting Protein Feed
In the process of selecting protein raw materials for creep feed for suckling piglets, digestibility is the first criterion for selecting protein raw materials, followed by good amino acid ratio and content. The key amino acids considered include lysine, sulfur-containing amino acids, threonine, tryptophan and histidine. Therefore, when selecting protein raw materials, it is best to choose raw materials with relatively high contents of the above amino acids and a reasonable ratio. At the same time, due to the limited feed intake of suckling piglets, it is necessary to try to find protein raw materials with high nutrient content to save space. Under the premise of limited feed intake, provide suckling piglets with diets of high nutrient concentration and good digestibility as much as possible, so as to ensure that they obtain ideal daily gain during the piglet stage as much as possible and lay the foundation for overall profitability.
2.2.1 Soybean products. Soybean products are currently the most abundant protein source. However, due to different processing techniques, there are many options for soybean product protein in suckling piglet and piglet feed: (1) Extruded soybeans are not only a source of soybean oil, but also a source of high-quality soybean protein, but the amount of extruded soybeans used should not be too much, generally not more than 15%. At present, there is no standard for extruded soybeans. Personally, I believe that if urease is below 0.05 and digestible protein is above 60%, it can be used; (2) Soybean meal is a plant protein, and its digestibility often cannot meet the requirements of suckling piglets. It also contains certain anti-nutritional factors, but it is a commonly used and suitable protein source for creep feed for suckling piglets; (3) Soy protein isolate, although its protein content is relatively high, because it is made from low-temperature soybean meal, may also contain a certain amount of anti-nutritional factors, so it can be enzymatically degraded during processing; however, because some products produce bitter peptides after enzymatic degradation, which affects palatability, when selecting, on the one hand it should have good solubility, and on the other hand it should also ensure good palatability. From the current application effect, it is very good, but the price is relatively high; (4) Soy protein concentrate. Soybean meal is soaked and dissolved in hot alcohol, removing part of the polysaccharides, which is equivalent to concentrating the protein, so its value is higher than ordinary soybean meal, but its digestibility is still limited; (5) Fermented soybean meal. After fermentation of soybean meal, digestibility is greatly improved, protein content is also somewhat increased, and anti-nutritional factors are destroyed. Therefore, fermented soybean meal may be the first-choice raw material for future suckling piglet and piglet feed. However, because different manufacturers use different fermentation strains and processes, the value for suckling piglet and piglet feed varies greatly, so caution is also needed when using it. At present, the amount of fermented soybean meal in creep feed for suckling piglets should not be too much, otherwise there will be negative effects.
2.2.2 Milk-derived protein. Generally, the main protein sources used as feed protein are high-protein whey powder and whey protein concentrate WPC-34. Their digestibility and amino acid composition are second only to plasma protein powder. If calculated purely by protein content, their price is not lower than plasma protein powder. They are now mostly used for human consumption, and the supply is relatively limited, so they cannot be used in large quantities in feed.
2.2.3 Plasma protein powder. Plasma protein powder has advantages in digestibility and absorption rate, amino acid composition and the speed of producing small peptides through degradation, and is a high-quality protein raw material for suckling piglets. Especially for homologous plasma protein powder, because it itself contains abundant small peptides and its amino acid composition is close to that of pigs, the effect is better. However, due to the possibility of homologous diseases, the use of this type of raw material should be cautious. In addition, its high price and unstable supply also limit the normalization of its use. If it needs to be used, the amount must reach 3% to have a significant effect, and it is best to choose the imported American product.
2.2.4 Intestinal mucosal protein (DPS). DPS is also a high-quality source of protein for suckling piglets, and it works very well when used together with plasma protein powder. DPS not only provides high-quality protein, but can also prevent weaning stress from damaging the intestinal mucosa of suckling piglets. Similarly, due to consideration of homologous diseases, caution is needed in use. At present, only the imported American product can be used, and its price is also relatively high. In addition, channels and supply are still limited.
2.2.5 Fish meal. Fish meal should be the high-quality protein raw material that everyone is most familiar with. When using it, freshness must be measured, the degree of adulteration identified, and physicochemical indicators tested. Because fish meal quality is really difficult to control, it is recommended not to use too much, preferably controlled below 2%.
2.2.6 Small peptide products. At present, many small peptide products are used in creep feed for suckling piglets, and they are also the hottest thing in the field of feed nutrition research recently. This type of product should belong to functional protein raw materials. Of course, there is still some time before mature and stable use, and it should be a high-quality protein source with very bright prospects in the future.
2.2.7 Other protein sources. For example, meat and bone meal, cottonseed meal, rapeseed meal, DDGS, etc. are still under research, and their usage should be strictly limited.
2.3 Key Points for Selecting Feed Additives
2.3.1 Drug additives. Under China's feeding environment, the use of medicinal additives in creep feed for suckling piglets is necessary. According to relevant regulations and announcements of China's Ministry of Agriculture, the currently selectable drug additives include virginiamycin, bacitracin zinc, colistin sulfate, nosiheptide, efrotomycin, enramycin, olaquindox, oxytetracycline, chlortetracycline, salinomycin, etc.
2.3.2 High copper and high zinc additives. When using high copper, do not use high zinc; conversely, when using high zinc, high copper is also not needed. In addition, high copper and high zinc have synergistic effects with drug additives. When using them, the doses of high copper and high zinc should not be too high. It is unnecessary and also likely to cause environmental pollution.
2.3.3 Enzyme preparations. Enzyme preparations are very good things, and research and application are continuing to deepen. Because the pelleting temperature of creep feed for suckling piglets will not be higher than 80°C, many enzyme preparations can be used. Years of application results show that the effect of compound enzymes is better than that of single enzyme preparations (except phytase).
3 Quality Control and Processing Key Points
Quality control and processing are extremely important work, but unfortunately many feed companies do not pay attention to them. A good creep feed formula for suckling piglets, with good raw materials, but without quality control and processing technology as a guarantee, still cannot produce a good creep feed product for suckling piglets. Only by closely combining the four aspects of formula, raw materials, quality control and processing can good products be produced. The six indicators implemented for national feed product formulation must be done by the feed mill's own laboratory. Some other key indicators also need to be sent to relevant units for testing on a regular basis. In fact, it does not cost much money or time, but can achieve very good results. For example, when using zinc sulfate produced in a certain place, whether its heavy metals exceed the standard can be determined by sending it for testing just once. It is only necessary to send it for testing again when changing the supply channel. The quality control department of CP Group is separated from the technical department and made independent, which is worth learning from.
To do a good job with creep feed for suckling piglets, it is best for one's own unit to be able to test important indicators such as starch gelatinization rate, soluble protein, fish meal freshness, peroxide value and some hygiene indicators such as Salmonella.
The quality control and processing of creep feed for suckling piglets are mostly the same as for other pig feed, with not much particularity. The only difference is that some heat-sensitive raw materials are used, so special attention must be paid to controlling pelleting temperature and conditioning time. Conditioning temperature has a great impact on starch gelatinization. It is reported that there is a negative correlation between conditioning temperature and gelatinization degree. The greater the temperature difference between the mash entering the pellet mill and the pellets leaving the mill, the higher the gelatinization degree.
Creep feed pellets for suckling piglets should not be made too hard, as being too hard seriously affects palatability. Looking at the entire feed processing process, apart from the feed formula, the processing techniques that affect feed pellet hardness include: raw material grinding technology, raw material extrusion and expansion technology, raw material mixing, water addition and oil spraying technology, steam pre-conditioning technology, die selection during the pelleting process, post-curing and post-spraying technology, and drying and cooling technology. Among these, especially the steam conditioning process, the conditioning effect directly affects the internal structure and appearance quality of the pellets. The longer the conditioning time, the higher the starch gelatinization degree, the denser the formed pellet structure, and the greater the hardness. Considering the physiological characteristics of the digestive tract of suckling piglets and feed digestibility, a higher starch gelatinization degree is required, so we need to appropriately reduce the hardness of creep feed for suckling piglets through other methods. Therefore, choosing a suitable compression ratio ring die is particularly important. Generally speaking, a pellet ring die compression ratio of 6-8 is sufficient. If a lot of extruded raw materials are used, a compression ratio of 3 is sufficient. The feed made in this way is crisp and loose, only with a slightly higher fines rate.
After extrusion, corn and soybeans are crushed, and particle size generally does not pose a problem. Other commonly used raw materials are mainly corn and soybean meal. The particle size after crushing has some influence on the digestion and absorption of suckling piglets. Generally speaking, suckling piglets and piglets have a stronger ability to chew feed than growing-finishing pigs. Whether corn or sorghum, whether crushed or extruded and broken, particle size has no effect on piglet growth rate. However, experiments have shown that when barley particle size is 635 microns, the growth rate is 5% higher than at 768 microns, and feed utilization is also improved, indicating that the effect of particle size on piglet production performance is also related to the type of raw material. The effect of particle size on the digestion and absorption of nutrients is also related to the interaction between the machine type and feed variety. Current research results show that, considering various factors comprehensively, a particle size of 400 microns to 600 microns is suitable.
If making mash feed, attention should be paid to mixing uniformity. Studies have shown that when the coefficient of variation of mixing uniformity of piglet feed decreases from 106.5% to 28.4%, the average daily gain increases by 41%, feed utilization increases by 18.52%, and feed intake increases by 18.33%. Therefore, the mixing time for weaned piglet feed should reach 4-6 min, and its coefficient of variation should be no more than 10% according to China's compound feed standard requirements, so as to ensure that the feed is fully mixed and nutrients are evenly distributed. Therefore, it is best to adopt a two-stage grinding process (after mixing evenly, grind once more). In this way, the product appearance is like that made from a single raw material, and it is also more uniform.
Recent studies have shown that the gelatinization rate of pellets has a huge impact on animal production performance. Data show that increasing the gelatinization rate by 5%-10% can improve animal production performance by 3%-5%, and the same effect also applies to creep feed for suckling piglets.
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Not bad, I learned something first, thanks to the original poster.
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Thank you. It took me 30 seconds to finish reading it quickly.
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This article is very well written. It has both a theoretical basis and practical accumulated content; but it is not complete enough. I rate it 95 points.