Most challenges faced by swine producers – whether they are nutritional, health or management related – tend to be seasonal. While fall is typically a favorable season for swine production, providing optimized weather conditions for growth during hot summers bring on a distinct set of obstacles.
Heat stress, for example, is a major concern in the summer – especially when hot temperatures are combined with high humidity. The optimal temperature, thermoneutral zone, for pigs post weaning is between 18°C and 24°C. When the temperature rises beyond the upper range of the thermoneutral zone, pigs are unable to dissipate heat without expending extra energy. Some of the impacts of heat stress include reduced feed intake, increased blood cortisol, inflammatory cytokines, blood pH (respiratory alkalosis), alterations in intestinal microflora, reduction in blood flow to the intestines and other internal organs and loss of intestinal integrity. Ultimately, in addition to being a welfare issue, heat stress leads to economic loss from decreased performance, reduction in meat quality and increased mortality.
Although we face many of the same issues from summer to summer, here are a few reminders on how to combat summertime challenges through nutrition, management and health considerations.
Nutrition
1. Adapt Your Formula for the Season
A decrease in performance during the summer primarily happens due to reduced feed intake. There are several adjustments that can be made to the diet to combat this. Formulation of nutrient-dense diets can help pigs maintain nutrient intake while less feed is consumed. Increasing energy levels in diets may also compensate for reduced feed intake. Because protein digestion produces higher levels of metabolic heat, this is often accomplished by increasing fat levels and lowering protein. If protein levels are reduced, however, amino acid levels must be carefully balanced, for example through synthetic amino acid and/or enzyme supplementation.
2. Maximize Feed Quality and Consider Pellet Feeding
While pigs consume less nutrients because of reduced feed intake, they can also get less nutrients by consuming poor-quality feed. Warm temperatures and high humidity provide optimal growing conditions for molds. Molds can reduce feed quality by utilizing the nutrients in the feed before it gets to the pigs. In addition, the mycotoxins produced by molds negatively affect almost all organ systems of the pigs along with reducing performance and feed efficiency. Performance loss from molds and mycotoxins can be combatted by adding mold inhibitors and flow agents to feeds. Similarly, antioxidants can protect fats and oils in feed from becoming rancid through oxidation. There is also evidence that pellet feeding during summer could help with increasing feed intake and mitigating performance loss during summer.
3. Supplement with Vitamins, Minerals and Systemic Antioxidants
Supplementation with vitamins can be useful in mitigating the effects of heat stress. Vitamins A, E and C supplementation may be beneficial not only because they are antioxidants which will help with oxidative stress caused by heat stress, but also because they are not synthesized as readily in heat-stressed pigs. Minerals such as calcium, phosphorus, zinc and magnesium, that are critical to growth and development, are lost either through reduced appetite and feed intake or from lowered metabolism during heat stress. These minerals should be properly balanced and if needed, supplemented to counteract this loss. Other minerals, such as chromium directly combat heat stress by reducing stress and cortisol levels. Supplementation with chromium can improve growth rate and yield during heat stress.
Health
4. Address the Immune System
One of the many detrimental effects of heat stress is an impaired immune system. Excessive heat tends to impair the ability of pigs to elicit optimum immune responses to vaccines and to fight off pathogens. While many producers associate the summer with less risk of disease and may use a less aggressive immune vaccination program during the summer months, it is critical that focus must be given to these programs. One way to help is to perform diagnostic surveys periodically in a subset of pigs to ensure that the vaccination program being used matches the challenges in the pigs. In addition, it is important to evaluate the efficiency of programs by looking at vaccine application and titers. Further, managing acute and chronic stress such as caused by heat stress is important to have a well-balanced immune system to fight off other challenges. A balanced diet with optimum amino acid ratio and minerals like zinc, copper and chromium have the potential to mitigate chronic stress and help keep the immune system balanced and ready for any challenges during summer. Feeding immune modulators like β-glucans, ideally before the start of summer, stimulates the immune system delicately without too much activation so that the animal is ready to face any immune and pathogenic challenges.
5. Focus on Diseases Through Proper Record Keeping
While historic data indicates that diseases in summer are less prevalent compared to winter, proper measures should be taken to protect the animals from diseases which are less prevalent, but become more aggressive, during summer. Prevalence of gastric ulcers and ileitis caused by Lawsonia increases during summer months. In grow-finish pigs, salmonellosis favors summer months compared to other seasons. While the number of erysipelas cases might be lower during summer months, there is some evidence that acute erysipelas seems to be more severe in summer months. While all three diseases have effective vaccines, it is important to follow the proper vaccination programs to prevent the outbreaks of these diseases during summer. Apart from these diseases, outbreaks during summer varies greatly from one farm to the other, and by geographical location. Proper record keeping is the key to identify and keep a check on diseases specific to a particular farm.
6. Focus on Maintaining Gut Health
A good intestinal health program is essential for a successful operation for all seasons, but it’s even more important during summer. The gastrointestinal (GI) tract is one of the first organ systems which gets affected severely during heat stress because the animal diverts blood flow to the peripheries to dissipate the heat. Also, the wide swings in temperature with the varying humidity during the different parts of the day in the summer contributes to high heat index and impacts the GI tract of the pigs significantly. The issues that result from an unhealthy gut are twofold. Firstly, as mentioned earlier, pigs tend to eat less during summer – consuming lesser nutrients than what is typically needed for optimum growth and production. If the intestine is not healthy and not working efficiently, this will compound the health issues significantly. Secondly, any pathogen or other toxic insult which enter the pig’s bloodstream because of the damaged intestine has the potential to start an inflammatory cascade –diverting vital nutrients which may already be in a deficient state. Gut health is of paramount importance to overcome any stress successfully. Probiotics, short chain fatty acids like butyric acid, minerals like zinc and copper, osmolytes, certain phytobiotics and antioxidants help maintain gut health during heat stress. You may also consider an organic or inorganic acid to protect a pig's GI tract from growth-limiting pathogens. Inhibition of pathogens promotes better gut health and production efficiency.
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Management
7. Ensure Ample, Clean Water Availability
Pigs consume more water as the temperature rises. It is important to have clean, cool water available to dissipate heat. Pigs should have a sufficient amount of drinker nipples/bowls and water pressure in each pen, and they should be properly maintained. Flushing lines regularly can help keep water clean and cool, which encourages pigs to drink more. As pigs drink more water, it attenuates the stress and feed intake tends to follow.
8. Maintain Evaporative Cooling Systems
Evaporative cooling systems need to be maintained to optimize cooling. Cool pads can lower the temperature in the barn significantly and combat heat stress, but there are factors that can lower the efficiency of systems. It is most important that pads and pipes don’t become clogged. Dirt and debris should be removed mechanically from pads and mineral deposits, and scale should be removed with a cleaner. Filters should also be flushed prior to use. Algae can clog pads and should be avoided by cleaning, limiting exposure to sunlight and allowing pads to dry out once a day. Wet-skin cooling using sprinkler systems or water-drop cooling are also desirable methods for the cooling of pigs.
9. Provide Adequate Ventilation and Floor Space
During the summer, it is critical to remove heat from the barn. Be sure to provide proper air flow uniformly throughout for tunnel ventilation. This can be accomplished by making sure barns are tightly sealed, and there are no holes in the walls or ceilings. It is also critical to have the correct number of fans and check that they are in good condition. This means ensuring fan belts are not loose, as well as making sure fan blades and shutters are clean as dust and loose belts can reduce airflow. Bearings should also be lubricated if needed. It is also desirable during summer to reduce stocking density to provide more floor space per pig to prevent crowding and overheating particularly in heavier pigs. Ideally, 1-3 pigs should be reduced from each pen depending on the nature of temperature extremes. Also, to reduce the stress to the pigs, handle them only during the cooler parts of the day, either in the morning or evening.
Conclusion
Finally, keep in mind that for an exceptional producer, the welfare of the pig should be the ultimate goal. All aspects of pig rearing are interconnected, and everything should be given equal attention. All the points discussed here provide a holistic approach toward the health and welfare of the pig. Utilized appropriately, they should provide the ideal growing condition for the pig and would allow the pig to realize its true genetic potential.
