Heat stress is one of the major environmental stressors in the livestock and poultry farming and processing industry. Researchers from China and abroad have found that when the environmental temperature and humidity exceed the tolerance range of farmed animals, they will suffer from heat stress reactions such as mental depression and reduced food intake. At this time, a series of physiological, biochemical and pathological changes such as changes in hormone levels and blood protein levels, and decreases in antioxidant capacity will occur, which can lead to body mass loss, meat quality deterioration, or death of livestock and poultry, causing irreparable economic losses. Animal farming is an important source of meat products and an important protein source in people’s dietary structure. The decrease in meat quality caused by heat stress not only causes economic losses, but also causes food nutrition and safety issues. This article summarizes the definition of heat stress in livestock and poultry, the behavioral and physiological response mechanism of heat stressed livestock and poultry, the impact of heat stress on meat quality, and the management measures for heat stress relief. It is hoped this article will provide a reference for the identification of and relief strategies for heat stress response in livestock and poultry.

The slaughter performance and the nutritional quality and processing quality of the meat of Laiwu black goats were analyzed by measuring dressing percentage, meat pH, meat color, cooking loss, crude protein, crude fat contents and the number of fast and slow muscle fibers. Sensory evaluation was also performed on meat samples. The results showed that there were significant differences in all tested parameters among goat carcasses slaughtered at different ages. However, there was no significant difference in dressing percentage between carcasses at 12 (48.21%) and 24 months (48.75%) of age, which was significantly higher than that (43.55%) at 8 months, and the meat to bone ratio at 12 months was 4.04, lower than that at 8 and 24 months. The meat color at 8 months of age was redder and brighter than that at other ages. The crude protein contents of goat meat at 8, 12 and 24 months were 19.29%, 21.34% and 22.00% respectively, and the crude fat contents were 1.83%, 2.08% and 2.10% respectively. The shear force of meat at 8 months was 4985.98 g, which was significantly lower than that at other ages. The best meat tenderness appeared at the slaughter age of 8 months. At this age, the number of fast muscle fibers was the highest and the ratio of fast to slow muscle fibers was 6.36, significantly higher than that at other ages; the sensory evaluation score was the highest. Based on the above experimental results, 8-month-old Laiwu black goats can be produced as high-grade lamb, and the slaughter benefit of 12-month-old lamb carcasses is higher.