Nonruminant Nutrition Symposium I
Dr. Chris Parks delivered the first talk about “Integrated Pork Production During a Global Pandemic: Impact on the Live Production Supply Chain, Feed Mills, & Nutrition''. According to him, the U.S. has an integrated pork system resulting from vertical integration. This means that a single company controls pork production from farmers to consumers allowing them to capitalize on the economics of the scale, create consistent products, and spread out risk. The COVID-19 pandemic had widespread impacts on the U.S. pork industry including long-term plant closures, shortages of workers, a backlog in the production-supply chain, and a lack of barn space for pigs. Beginning in the Midwestern region and continuing into the Southeastern region, there were reductions in the processing capabilities of plants that led to the accumulation of heavy finishing pigs. In order to mitigate these effects, management and nutritional tools were tested and utilized to slow growth and reduce feed intake of the animals. Strategies included feed restriction, temperature manipulation, increased stocking density, and flow reduction to reduce the growth rate of the pigs. Nutritional approaches included feeding high fiber diets, using calcium chloride to reduce electrolyte balance, removing growth promotion additives, using high vomitoxin ingredients, low protein diets, and amino acid manipulation to reduce growth rate and feed intake. The most important impact on rate of gain and feed intake came from high methionine diets that could also be instituted quickly. While moderately successful, some strategies resulted in sub-optimal carcass quality, ulcers, and other vice behavior. Overall, Dr. Parks found that it was important to develop a plan, execute early and then reevaluate constantly. All options must be considered and conducting research is best if possible. Finally, industry and university relationships are important to cultivate now so that there is assistance when disaster strikes.
Dr. Ehsan Khafipour presented next about “Swine Microbiomes and Viral Infections: Lesson Learned from Recent Human and Swine Pandemics”. Many of the complications on the human side from COVID-19 can be applied in swine. The microbiome is the bacterial, archaeal, and overall microbial community inside the animal. Different methods of sequencing can be used to look at different communities and functions of interest. The microbiome has a role in infections because the loss of microbial diversity which predisposes animals to pathogens. Over time microbial diversity is affected by several factors. These include genetic selection, modernized production systems which reduce environmental exposure, and the use of antibiotics which increases the depletion of microbes which leaves the host more susceptible to infections. In the pandemic level transfer of viral pathogens among individuals, there is a race between the host and the pathogen as the host tries to combat the pathogen. In pathogenic infection, the fitness cost for tolerating the pathogen is often unknown. Pathogens can regain virulence in the body, cytokine storms can further disrupt microbiome diversity, and co-infections can also occur which increases the severity of the outcome. During pandemics, the acquisition and the loss of microbes needs to be balanced. Diets with low function, antibiotics/antimicrobials, modernized production system, immune reaction, and inflammation can deplete microbes or reduce them. There is a progression of the microbiome in the early life of piglets. Those who get the space first define who gets the space next. This means that there is a substantial role of the environment to educate the immune system which results in development of selective pressure that excludes colonization of certain environmental bacterial lineages. Early events define robustness and resilience of microbiomes later in life that allow them to resist change from pathogenic organisms. Health includes probability of developing disease as the susceptibility for viral infection is not the same for all. When microbiota lose control, there is an overwhelming inflammatory response. This leads to a loss of sources for the animal to protect itself, depletion of beneficial bacteria, increased cytokines and inflammation, and more opportunistic pathogens. In treating viruses such as COVID-19, antimicrobials have been used. However, while antimicrobials suppress opportunistic pathogens, they also deplete beneficial microbes. The resulting cytokine storm is the number one cause of mortality in humans infected with COVID-19. The second leading cause is coinfection with a virus, fungus, or bacteria from the depletion of microbes. To reduce the severity of viral infection there are several treatments that can be used. These include antimicrobials but also prebiotics that selectively promote the growth of beneficial microbes, postbiotics which are a combination of metabolites that allow for microbes to flourish, probiotics, and fecal microbiota transplantation. Antibiotics can be effective but in suppressing a group of microbes, opportunity is given for harmful ones to flourish and there are long-term costs in antibiotic resistance and loss of beneficial microbes. Overall, proper balance of the microbiome influences the severity of viral infections.
Dr. Chad M. Pilcher spoke next about “Precise Nutrient Supply Drives Successful Pork Production During Economic Uncertainty”. According to him, in defining success in pork production, several factors need to be considered. These include human and animal health, safety, and welfare, and business sustainability and profitability. In the nutrition decision making process, it is important to understand the supply of nutrients, quantify animal demand, and optimize business profitability. Initially in 2020, the U.S. pork industry outlook for estimated profitability was promising, but then the onset of the COVID-19 pandemic occurred. Particularly in the Midwestern U.S., in March of 2020, packing plants greatly increased production and a greater number of pigs were harvested to create a buffer. However, eventually, the packing plant could not handle the amount of animals due to lack of employees and came to Dr. Pilcher to see how a 10% and then 20% harvest reduction scenario would affect them. At 20% and over, the pigs would be larger than acceptable for most packing plants. Therefore, other plans needed to be formulated to adjust to the capabilities of the packing plants by slowing down the growth rate of the pigs. Strategies included keeping net energy low, reducing lysine and tryptophan, removing growth promoting feed additives, and double stocking to increase space. While somewhat effective, no method or combination could mitigate the effects of a 20% harvest scenario and the actuality was that the scenario worsened and many plants ended up closing temporarily for COVID-19 quarantines. However, there was very little controlled data on intentionally slowing growth of finishing pigs and there was an immediate need for strategy development. Nutritional methods were considered in preventing rapid growth. These included high fiber and low energy diets, altered Calcium and Phosphorus balance, altered protein and amino acid restriction, acid-base balance, and the use of calcium chloride. Feed restriction, stocking density and elevated barn temperature were also considered to slow growth. University help was received todo research to evaluate dietary strategies. Eventually, once the number of pigs for slaughter was very backed up, the price of meat started to rise and plans needed to be reformulated. Plants needed to be formulated again once the Defense Production Act was enacted and food production rose up rapidly. More pigs were slaughtered than expected allowing a full recovery. However, pork prices dropped again leading to the reformulation. The research from the university showed that reduced gain was observed for pigs on a corn diet and an even more reduced gain was observed on the calcium chloride diet. The corn diet was the most commonly utilized due to ease of implementation and was often combined with other management techniques. Calcium chloride was found to be the most effective option if feed intake and growth need to be dramatically reduced. Overall, Dr. Pilcher found that it was essential to emerge resiliently and create flexible plans using facts, and that pig growth can be successfully slowed using nutritional strategies.
Michael S. Edmonds concluded the symposium with “Amino Acid Imbalance with Excess Methionine in Late-finishing Pigs: Effects on Performance and Carcass Quality”. According to him, the COVID-19 pandemic shut down numerous pork harvest facilities and led to complications in supply chain and economic hardship. It became necessary to determine how to slow growth rate in late finishing pigs. Amino acid imbalance in the diet allowed for the reduction of weight gain and feed intake. Preliminary trials were done using methionine. Feeding methionine with a corn diet led to a substantial reduction in growth because of reduced feed intake. When a diet with an increased methionine was fed, there were marked reductions in weight gain compared with a low protein diet and no methionine. Carcass data showed that pigs fed methionine had lower back fat but all had a similar dressing percentage. The cost of the high methionine diets per kilogram was much greater than the control but the cost per day was slightly less. In a second trial, a more aggressive treatment with methionine was used with the greatest reduction in weight gain and feed intake in the diet with the highest percentage of methionine. In that treatment, pigs lost weight per day rather than gaining. For all methionine treated pigs, percent lean of the carcass was over 56% and the dressing percentage was around 75%. Overall, excess methionine has been shown to reduce growth rate in finishing pigs.