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Pigs are exceptionally sensitive to heat stress compared to other livestock, and during periods of hot weather, it's crucial to consider strategies for mitigating this issue.
The current article provides a cautionary note from an American study and outlines practical steps to minimize heat stress in pigs.
Why Are Pigs Vulnerable to Heat Stress?
Unlike many animals that can manage body temperature by sweating and panting, pigs lack these natural cooling mechanisms due to their non-sweating nature and smaller lung capacity. Their thick subcutaneous fat also contributes to their susceptibility to heat stress. The two most noticeable symptoms are increased respiration rate and loss of appetite, which reduce internal heat production.
Modern Pig Genetics: Increased Heat Production
A comprehensive review by Brown-Brandl et al. 2003 found that contemporary pig genotypes produce about 20 more heat than predecessors from the early 1980s. This tr has likely continued and may be even higher, with estimates of an additional 10 increase since then.
Impact on Pig Performance
Larger pigs are at greater risk of heat stress, leading to larger reductions in growth performance compared to smaller ones. As shown in Figure 1, when ambient temperatures rose from 14°C to 35°C, average dly gn ADG began to decrease notably in pigs weighing over 75 kg at the temperature threshold of 23°C. For smaller pigs weighing around 25 kg, this decline occurred above a 27°C temperature threshold.
Critical Temperature for Performance Decline
Figure 2 illustrates how pig body weight significantly influences critical temperatures for average dly feed intake ADFI and average dly gn ADG. This data can assist in tloring management strategies for various age groups of pigs housed in different sheds.
Temperature and Humidity Thresholds
Both ambient temperature and humidity contribute to heat stress, with pigs experiencing it at lower temperatures under high humidity conditions. The Iowa State University's heat stress index chart Figure 3 serves as a decision tool for implementing management practices that reduce heat stress. As shown in the chart, conditions during Western Australian summers often exceed recommed limits an average humidity of 30 combined with temperatures above 28°C negatively impact gut health and pig performance.
Impact on Intestinal Health
A recent study by Pearce et al. 2013 found that heat stress damages intestinal defense function in pigs, leading to increased plasma otoxin levels. This damage becomes more pronounced even with short-term exposure of two to six hours, potentially allowing for easier pathogenic bacteria invasion and secondary infection when sanitary conditions are suboptimal.
Strategies to Reduce Heat Stress
Implementing management tools such as increased ventilation and rflow, ensuring a functional cooling system e.g., spray cooling, reducing pig density if feasible, mntning drinking water temperature ideally around 10°C challenging but attnable goal while avoiding feeding between the hottest hours of 10:00 am to 4:00 pm.
Supplementation of electrolytes and antioxidants through water supply can also be beneficial. Increasing dietary energy density might help cope with the heat, minimizing excess non-essential amino acids and fiber which reduces intestinal fermentation and heat production while increasing antioxidant avlability in the diet via vitamins like E or betne supplements.
By following these guidelines, livestock farmers can enhance their pigs' health and productivity during summer months and protect them agnst the detrimental effects of heat stress.
External Resources
Heat Stress Index Chart for Swine Producers
Seasons: Summer
Please share this information widely to educate others on effective heat management strategies.
Contact:
Department of Primary Industries and Regional Development - Agriculture and Food division, committed to growing and protecting WA's agriculture sector.
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South Perth, WA 6151,
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WA 6983
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Contact Information:
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Fax: +61 08 9474 2405
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This article is reproduced from: https://www.agric.wa.gov.au/feeding-nutrition/heat-stress-pigs
Please indicate when reprinting from: https://www.ub47.com/Veterinary_sow/Heat_Stroke_in_Pigs_Cooling_Strategies.html
Heat Stress Management in Pigs Pig Genetics and Heat Production Critical Temperatures for Pig Performance Impact of Humidity on Heat Stress Strategies to Reduce PIG Heat Stress Enhancing Intestinal Health Under Heat