Interpretation of the Latest Research Progress on Porcine Epidemic Diarrhea
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The Unchanging Rhythm | The Latest Research Progress on Porcine Epidemic Diarrhea
PED is a disease caused by a coronavirus, characterized by severe watery diarrhea throughout the herd in the early stages of onset and a high mortality rate in young piglets. Visible symptoms include vomiting, loss of appetite, diarrhea, emaciation and death. Necropsy reveals undigested milk in the stomach and intestinal walls that are thin and nearly transparent. The mortality rate of piglets over 10 days of age is about 10%, but the mortality rate of piglets under 5 days of age can reach 100%.
In Asia, PED was first recorded as breaking out in South Korea in the 1890s and quickly spread to other countries. It is now widely prevalent in many countries, including many farms that are trying to coexist with it or trying to isolate it through biosecurity. The United States confirmed its first PED outbreak on May 13, 2013, and the disease has now spread to 30 states.
The U.S. pig industry has suffered extremely heavy losses. In 2013 alone, the United States was estimated to have lost about 3 million piglets due to PED, and the loss was expected to reach 6 million by 2014. Although producers offset part of the losses by improving production efficiency and increasing slaughter weight, it still caused pork price increases in recent months and affected exports. The PED strain isolated in the United States is 99% similar to the Chinese Anhui strain.
At the World Pork Expo in May 2014, there were many reports on PED. The research director of swine health at the (U.S.) National Pork Board reported the latest research progress and disease dynamics of PED in the United States. They found that, similar to the situation in Asia, piglets may show clinical symptoms 2-3 days after exposure to the virus, and as the viral load increases, the incubation period shortens further. In Asia, when PED breaks out, piglets only one day old develop diarrhea. The report pointed out that after a herd is infected with PED, viral shedding begins in 1-2 days, peaks at 5-6 days, and lasts for 35 days. Although a very large number of PED disease cases broke out in the United States within a very short period, the transmission route of PED is still fecal-oral, and shedding or transmission through aerosols has not yet been reproduced under laboratory conditions. However, the virus may possibly spread between farms with the wind. Virus stability studies by a University of Minnesota laboratory showed that the PED virus can survive for 14 days in fresh feces at 40°C to 50°C, for 7 days at 60°C, for 14 days in manure slurry at 25°C, and for at least 28 days in manure slurry at -20°C to 3.89°C (the experiment only went to 28 days). At present, transmission through feed is suspected to be the main route of PED outbreak spread in the United States, and the PED virus has been found to survive for 1-2 weeks in dry feed.
Post-weaning PED Control Strategies for PED-infected Farms
PIC proposed a post-weaning care strategy for PED to help weaned piglets that may be infected with PED survive and grow better during a PED outbreak or epidemic.
Piglets infected with PED have reduced nutrient absorption due to damage to the small intestine and need a certain amount of time to recover. Because of reduced enzyme activity, small intestinal damage will make it difficult for piglets to digest milk-derived food or feed. Therefore, getting them to transition away from milk-derived food as quickly as possible helps them survive. In addition, we should also consider other key points to control PED infection.
4 Key Points for Piglet Care
We need to focus on these 4 key points to improve piglet survival rates: drinking water, feed intake, activity level and environment.
Drinking Water
We must ensure that piglets are provided with enough water so that, in addition to meeting normal drinking needs, they can promptly replenish lost body fluids. One water source is needed for every 10 pigs, and a pen with 20 pigs needs at least 2 water nipples or water bowls. The flow rate must be at least 500 ml/minute, and the pressure must be less than 20 psi (excessive pressure makes it difficult for pigs to drink). To "teach" piglets where to find water, keep dripping water or make the nipple/bowl leak for the first few hours.
Providing extra water troughs for piglets when weaning and moving to the nursery is beneficial. Add electrolytes for the first 3-5 days. A common problem on farms is that weaned pig pens have more than 2 water nipples, but they are installed at different heights, with the low one for small pigs to drink and the other high one for larger pigs. This configuration is a problem for newly weaned piglets, meaning that the vast majority of piglets may only be able to reach one nipple. The height of the nipple must not exceed the shoulder of the smallest piglet in the pen. Adjustable-height nipples will better meet the needs, because they can be adjusted according to the pigs in the pen.
Activity Level
The key is to get piglets up multiple times a day to stimulate them to maintain the activity pattern of getting up and lying down many times under farrowing crate conditions. In the farrowing crate, piglets suckle regularly at a cycle of about 2 hours. Facts have shown that during the first 4 days after weaning, getting piglets up once every 2-3 hours according to this cycle can help piglets learn to drink water and eat feed faster. Piglets can be trained to eat feed using gruel (wet feed) or small-quantity feeding (top-dressing feeding).
For the first 2 weeks, fill each pen to maximum capacity, but ensure that each piglet has enough space and avoid overstocking pigs.
A Good Environment
What is a "good" environment? A good environment can be defined as one in which dry, comfortable piglets can be seen. Piglets with diarrhea or dehydration usually need a higher temperature, and different types of flooring require different temperature settings and need to be adjusted promptly:
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If mats are used, the temperature under the central heat lamp should be 35°C, with 0.05 sq m of space per piglet. If the mat is wet, it must be turned over or replaced. If the floor is wet and the humidity is greater than 65%, the temperature can be temporarily increased and the fan speed reduced. Maintain the starting temperature for one week after entering the pen.If a mat is used, the temperature under the central heat lamp should be 35°C, with 0.05 sq m of space per piglet. If the mat is wet, it must be turned over or replaced. If the floor is damp and the humidity is above 65%, the temperature can be temporarily increased and the fan speed reduced. Maintain the starting temperature for one week after entry into the pen.
Feeding
As mentioned above, if piglets can quickly and regularly begin eating, the growth performance of weaned pigs will be significantly improved. Facts have shown that providing gruel (wet feed) multiple times a day has a very good effect. Here is an example formula: for every 15 piglets, they should finish within 1 hour a wet feed made by mixing 227 g of feed and 750 ml of water.
For top-dressing feeding, for every 30-40 piglets, scatter 0.45 kg of feed on the mat at least 4 times a day. The purpose of scattering feed is to stimulate feed intake rather than to actually feed. Once piglets become accustomed to the feed and feeding, they will eat from the trough. Check the coverage rate of the trough bottom pan to ensure that the feeding amount is sufficient and that feed crumbling and waste are minimized. Newly weaned piglets must eat fresh feed, the feed pan must be cleaned twice a day, and the coverage rate should be maintained at 50%.
Biosecurity
Biosecurity measures must be strictly implemented to minimize disease transmission between pens and barns. All facility areas contaminated by PED must be isolated. A separate, isolated group of people is needed to work in these areas. Showering in and out is equally important. Transport is regarded as the main factor in the rapid spread of PED in the United States. After transport is completed, vehicles must be cleaned, dried and disinfected. Dead pigs must be disposed of by incineration or composting. When the barn is emptied, ensure that the facility is strictly cleaned, organic material is removed, and manure is cleared. All clothing must be changed or strictly washed and dried.
These 4 key points will help manage newly weaned piglets infected or not infected with PED, and should be implemented in all production systems.
We hope to learn more experience from others, just as they learn from us.
