Why Culled Hens Are Underweight: Causes and Solutions
Introduction: EhtmlPUBLIC"-//W3C//DTDXHTML1.0Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional
|Email|RSS|Chinese Academy of Agricultural Sciences
Your current position: Home > 100,000 Whys
|
Why culled hens are underweight, what causes it, and how to solve it
Author: Article source: Shanxi Farmers' Daily Published: 2018-02-28 Views:
Laying hens are raised to 72-78 weeks of age and then culled for meat use. Different breeds have different body weight standards at culling; for example, the average body weight of White Leghorn chickens is 1.8 kg, while the average body weight of Hy-Line Brown chickens is 2.25 kg. The body weight at culling not only affects the value of the culled hens, but also indirectly reflects the production performance during the laying period. In production, it is common for culled hens to be too light (10%-15% below the standard body weight) and to have severe feather loss, which directly affects the farm's profitability. The causes of culled hens being underweight are analyzed below and solutions are proposed.
Cause analysis
Poor quality of reared new hens
Purchased chicks are small and weak, with severe contamination, causing slow growth and development during the brooding and rearing periods; poor management during brooding and rearing, such as poor initial feeding, unsuitable temperature and humidity, excessive beak trimming, insufficient feeding and drinking space, and overcrowding of the flock, seriously affect flock development; poor feeding during brooding and rearing, with low nutrient concentration, unbalanced nutrition, poor quality, and insufficient feed, leading to poor flock development, small bones, and light body weight; poor isolation and sanitation conditions during brooding and rearing, irregular disinfection, unscientific formulation and operation of vaccination programs, and many stress factors cause frequent diseases in the flock, severely hindering growth and development, resulting in low body weight and poor uniformity. Reared new hens with small bones, light body weight, and uneven size will find it very difficult to reach the standard body weight requirements at culling.
Little weight gain in the early laying period
In the early laying period (20-32 weeks of age), body weight still increases considerably, and at this stage, as the laying rate rises, body weight should increase in sync. For example, the body weight gain requirements for ISA White egg-laying hens are: when the laying rate is 10%, body weight is 1360 g; when the laying rate is 40%, body weight is 1450 g; when the laying rate is 70%, body weight is 1500 g; when the laying rate is 90%, body weight is 1560 g. If weight gain is too small, it will not only affect the laying performance during the laying period, but also require greater subsequent weight gain to bring body weight up to standard, which must consume more feed and severely reduce feed conversion rate during the laying period. The causes affecting weight gain include: (1) Poor feed quality. On one hand, the designed formula has low nutrient concentration and cannot meet the hen's needs. On the other hand, high-quality raw materials on the market such as soybean meal and fish meal are in short supply and high in price, so feed manufacturers, in order to compete for the market and lower feed prices, use large amounts of miscellaneous meals, medicinal residues, keratin powder, and other inferior raw materials to prepare feed, resulting in poor protein quality, many harmful substances, and low digestibility and absorption rate. (2) Switching to layer feed too late. The nutrient levels of rearing feed and pre-laying feed are lower than those of layer feed. If layer feed is switched too late, it affects the accumulation of nutrients; although it may not temporarily affect the rise in laying rate, it will affect weight gain. (3) Low feed intake. Generally, lighting should be increased at 19-20 weeks of age. With light stimulation, the laying rate rises quickly, so feed quantity must be increased 1-2 weeks in advance to ensure that the light effect during the laying period is synchronized with nutrition. If light is increased without increasing feed, weight gain will be affected; if the start of laying occurs in hot summer, poor heat prevention and cooling measures and excessively high house temperature lead to low feed intake by the flock; improper feeding methods, such as too much feed left in the trough for too long, causing deterioration or off-flavors, result in poor appetite and affect feed intake. (4) Disease. When diseases occur in the flock, such as Marek's disease, Newcastle disease, infectious bursal disease, avian influenza, fowl pox, infectious laryngotracheitis, and some chronic diseases, they all affect hen weight gain.
Poor feeding during the laying period
High-yielding commercial hybrid hens have high production potential and high nutrient requirements and large needs, so they must be provided with a comprehensive, balanced, and sufficient diet. If nutrient supply is insufficient, it will inevitably affect the expression of production performance and the maintenance of body weight. Insufficient nutrient supply during the laying period is an important cause of low body weight and feather loss in culled hens. Insufficient nutrient supply has two aspects. First, feed problems. In recent years, feed raw materials have continued to rise in price, especially high-quality raw materials such as soybean meal and fish meal are in short supply and their prices keep climbing. Farmers who mix their own feed have reduced use because of the high cost of ingredients, and most choose concentrated feed produced by feed manufacturers. In order to expand the market, increase sales, and reduce ingredient costs, feed manufacturers continuously lower the nutritional level of the diet and choose miscellaneous meals and some unconventional feed raw materials. As a result, the feed's nutrient concentration is low and digestion and absorption efficiency are poor, causing low laying rate, small egg weight, and light body weight. Second, feeding problems. The laying hen industry has thin profits, and farmers, in order to reduce feeding costs, neither understand the nutritional content of the diet nor know the hens' nutritional requirements and the amount of nutrients actually consumed, and blindly restrict feeding. As a result, nutrients are supplied insufficiently for a long time, body nutrients are over-consumed, body weight decreases, and feathers fall off prematurely.
Solutions
Raise new hens with a body type that meets requirements
New hens with a good body type have fully developed bones, standard body weight, and moderate fatness. With good feeding and management during the laying period, their production performance can be fully expressed, and their body weight at culling is also relatively ideal. If bone development is poor and body size is small, it will not only affect laying performance but also affect body weight. Even with good feeding and management, a flock with small bones cannot achieve a relatively large body weight. Therefore, feeding and management during the brooding and rearing periods should be strengthened: select healthy, large, uniform, and clean day-old chicks; maintain appropriate rearing density, feeding and drinking space, and suitable and stable temperature and humidity; ensure sufficient, balanced, and comprehensive nutrient supply; do a good job in sanitation management and disease prevention and control; and enable the flock to grow and develop healthily and normally. Special attention should be paid to nutrient supply in the early brooding period. A diet with a higher nutrient level can be used, such as broiler starter feed or chick crumble, to ensure the rapid early development of bones and body weight.
Strengthen feeding and management during the laying period
At 17-18 weeks of age, layer feed should be switched in a timely manner. During the rising laying period, feed quantity should be continuously increased with the increase in laying rate and lighting. Before 45 weeks of age, do not restrict feeding; feed sufficiently. After 45 weeks of age, exploratory feed reduction techniques can be used to appropriately restrict feeding. During the laying period, the positions of feed troughs and water troughs should be sufficient. Feed should be evenly distributed 1-2 hours after feeding. The hens should be allowed to clean up the trough every day. Generally, water should not be restricted. Different feeds can be switched at different laying stages, but the nutritional level of the feed must meet the nutritional needs of laying hens. Choose high-quality feed raw materials to ensure the feed is comprehensive, balanced, and sufficient in nutrition, and use as few miscellaneous meals and unconventional feed raw materials as possible. If miscellaneous meals are used to replace soybean meal, the nutritional differences between miscellaneous meals and soybean meal, the utilization efficiency of amino acids, and the harmful and toxic substances in miscellaneous meals should be considered, and they should be used as substitutes reasonably. Treat miscellaneous meals for detoxification to remove or reduce their harmful and toxic substance content; determine appropriate usage amounts and the proportions of various miscellaneous meals; design formulas based on available amino acids; appropriately add synthetic amino acids and increase the addition of vitamins and trace elements so that nutrition can better meet needs; and use enzyme preparations to improve the digestibility and utilization rate of miscellaneous meals.
Fatten at the appropriate time
After a long laying cycle, high-yielding laying hens can produce 18-20 kg of eggs per hen, requiring the consumption of large amounts of nutrients. Body nutrients become depleted, and the flock is generally thin and light in body weight. If feeding and management are poor, this situation will become even more serious. In order to supplement body nutrients and ensure appropriate body weight, fattening should be carried out at the appropriate time. The fattening method is: stop feed restriction 5-7 weeks before culling and allow free feeding; add an extra 5%-6% corn or 2%-3% oil to the feed to increase the dietary metabolizable energy level; and appropriately supplement additives such as vitamins, trace elements, and choline chloride. This will neither affect egg production nor allow the flock's body weight to recover as quickly as possible, so that there is an appropriate body weight at culling.
Cause analysis
Poor quality of reared new hens
Purchased chicks are small and weak, with severe contamination, causing slow growth and development during the brooding and rearing periods; poor management during brooding and rearing, such as poor initial feeding, unsuitable temperature and humidity, excessive beak trimming, insufficient feeding and drinking space, and overcrowding of the flock, seriously affect flock development; poor feeding during brooding and rearing, with low nutrient concentration, unbalanced nutrition, poor quality, and insufficient feed, leading to poor flock development, small bones, and light body weight; poor isolation and sanitation conditions during brooding and rearing, irregular disinfection, unscientific formulation and operation of vaccination programs, and many stress factors cause frequent diseases in the flock, severely hindering growth and development, resulting in low body weight and poor uniformity. Reared new hens with small bones, light body weight, and uneven size will find it very difficult to reach the standard body weight requirements at culling.
Little weight gain in the early laying period
In the early laying period (20-32 weeks of age), body weight still increases considerably, and at this stage, as the laying rate rises, body weight should increase in sync. For example, the body weight gain requirements for ISA White egg-laying hens are: when the laying rate is 10%, body weight is 1360 g; when the laying rate is 40%, body weight is 1450 g; when the laying rate is 70%, body weight is 1500 g; when the laying rate is 90%, body weight is 1560 g. If weight gain is too small, it will not only affect the laying performance during the laying period, but also require greater subsequent weight gain to bring body weight up to standard, which must consume more feed and severely reduce feed conversion rate during the laying period. The causes affecting weight gain include: (1) Poor feed quality. On one hand, the designed formula has low nutrient concentration and cannot meet the hen's needs. On the other hand, high-quality raw materials on the market such as soybean meal and fish meal are in short supply and high in price, so feed manufacturers, in order to compete for the market and lower feed prices, use large amounts of miscellaneous meals, medicinal residues, keratin powder, and other inferior raw materials to prepare feed, resulting in poor protein quality, many harmful substances, and low digestibility and absorption rate. (2) Switching to layer feed too late. The nutrient levels of rearing feed and pre-laying feed are lower than those of layer feed. If layer feed is switched too late, it affects the accumulation of nutrients; although it may not temporarily affect the rise in laying rate, it will affect weight gain. (3) Low feed intake. Generally, lighting should be increased at 19-20 weeks of age. With light stimulation, the laying rate rises quickly, so feed quantity must be increased 1-2 weeks in advance to ensure that the light effect during the laying period is synchronized with nutrition. If light is increased without increasing feed, weight gain will be affected; if the start of laying occurs in hot summer, poor heat prevention and cooling measures and excessively high house temperature lead to low feed intake by the flock; improper feeding methods, such as too much feed left in the trough for too long, causing deterioration or off-flavors, result in poor appetite and affect feed intake. (4) Disease. When diseases occur in the flock, such as Marek's disease, Newcastle disease, infectious bursal disease, avian influenza, fowl pox, infectious laryngotracheitis, and some chronic diseases, they all affect hen weight gain.
Poor feeding during the laying period
High-yielding commercial hybrid hens have high production potential and high nutrient requirements and large needs, so they must be provided with a comprehensive, balanced, and sufficient diet. If nutrient supply is insufficient, it will inevitably affect the expression of production performance and the maintenance of body weight. Insufficient nutrient supply during the laying period is an important cause of low body weight and feather loss in culled hens. Insufficient nutrient supply has two aspects. First, feed problems. In recent years, feed raw materials have continued to rise in price, especially high-quality raw materials such as soybean meal and fish meal are in short supply and their prices keep climbing. Farmers who mix their own feed have reduced use because of the high cost of ingredients, and most choose concentrated feed produced by feed manufacturers. In order to expand the market, increase sales, and reduce ingredient costs, feed manufacturers continuously lower the nutritional level of the diet and choose miscellaneous meals and some unconventional feed raw materials. As a result, the feed's nutrient concentration is low and digestion and absorption efficiency are poor, causing low laying rate, small egg weight, and light body weight. Second, feeding problems. The laying hen industry has thin profits, and farmers, in order to reduce feeding costs, neither understand the nutritional content of the diet nor know the hens' nutritional requirements and the amount of nutrients actually consumed, and blindly restrict feeding. As a result, nutrients are supplied insufficiently for a long time, body nutrients are over-consumed, body weight decreases, and feathers fall off prematurely.
Solutions
Raise new hens with a body type that meets requirements
New hens with a good body type have fully developed bones, standard body weight, and moderate fatness. With good feeding and management during the laying period, their production performance can be fully expressed, and their body weight at culling is also relatively ideal. If bone development is poor and body size is small, it will not only affect laying performance but also affect body weight. Even with good feeding and management, a flock with small bones cannot achieve a relatively large body weight. Therefore, feeding and management during the brooding and rearing periods should be strengthened: select healthy, large, uniform, and clean day-old chicks; maintain appropriate rearing density, feeding and drinking space, and suitable and stable temperature and humidity; ensure sufficient, balanced, and comprehensive nutrient supply; do a good job in sanitation management and disease prevention and control; and enable the flock to grow and develop healthily and normally. Special attention should be paid to nutrient supply in the early brooding period. A diet with a higher nutrient level can be used, such as broiler starter feed or chick crumble, to ensure the rapid early development of bones and body weight.
Strengthen feeding and management during the laying period
At 17-18 weeks of age, layer feed should be switched in a timely manner. During the rising laying period, feed quantity should be continuously increased with the increase in laying rate and lighting. Before 45 weeks of age, do not restrict feeding; feed sufficiently. After 45 weeks of age, exploratory feed reduction techniques can be used to appropriately restrict feeding. During the laying period, the positions of feed troughs and water troughs should be sufficient. Feed should be evenly distributed 1-2 hours after feeding. The hens should be allowed to clean up the trough every day. Generally, water should not be restricted. Different feeds can be switched at different laying stages, but the nutritional level of the feed must meet the nutritional needs of laying hens. Choose high-quality feed raw materials to ensure the feed is comprehensive, balanced, and sufficient in nutrition, and use as few miscellaneous meals and unconventional feed raw materials as possible. If miscellaneous meals are used to replace soybean meal, the nutritional differences between miscellaneous meals and soybean meal, the utilization efficiency of amino acids, and the harmful and toxic substances in miscellaneous meals should be considered, and they should be used as substitutes reasonably. Treat miscellaneous meals for detoxification to remove or reduce their harmful and toxic substance content; determine appropriate usage amounts and the proportions of various miscellaneous meals; design formulas based on available amino acids; appropriately add synthetic amino acids and increase the addition of vitamins and trace elements so that nutrition can better meet needs; and use enzyme preparations to improve the digestibility and utilization rate of miscellaneous meals.
Fatten at the appropriate time
After a long laying cycle, high-yielding laying hens can produce 18-20 kg of eggs per hen, requiring the consumption of large amounts of nutrients. Body nutrients become depleted, and the flock is generally thin and light in body weight. If feeding and management are poor, this situation will become even more serious. In order to supplement body nutrients and ensure appropriate body weight, fattening should be carried out at the appropriate time. The fattening method is: stop feed restriction 5-7 weeks before culling and allow free feeding; add an extra 5%-6% corn or 2%-3% oil to the feed to increase the dietary metabolizable energy level; and appropriately supplement additives such as vitamins, trace elements, and choline chloride. This will neither affect egg production nor allow the flock's body weight to recover as quickly as possible, so that there is an appropriate body weight at culling.
Print article Close this page
For more professional agricultural science and technology information, please scan the QR code to follow WeChat: NongXunNET
Please indicate the source when reprinting.