The effect of heat stress on the fertilization of sows and litter size

Abstract. The study of the effect of heat stress on the reproductive parameters of pigs is an urgent problem all over the world. Knowing the degree of influence of heat stress on pigs of different breeds will allow you to choose economically sound solutions to this problem in specific conditions. The propose is to study the effect of heat stress on some indicators of reproduction of sows of different breeds (large white, landrace, duroc, MAXGRO). Methods. The study was conducted on a large pig breeding complex. The material for the analysis was data on changes in air temperature in the breeding farm in the period from June to August (13 weeks) and data on the fertilization and duration of pregnancy of sows fertilized during this period and the size of the offspring obtained from them. Scientific novelty. For the first time, a comparative analysis of the effect of heat stress on fertilization, duration of pregnancy and the size of the offspring of sows of four breeds – large white, landrace, duroc, MAXGRO – was carried out on a wide population of pigs. Different sensitivity of sows to heat stress was revealed. Results. From the 4th to the 6th week of the experiment, the sows were in a state of increasing heat stress – the average daily temperature during this period increased to 27.68 ± 1.36 °C. The negative effect of hyperthermia on fertilization was recorded with a delay of 1–3 weeks, depending on the breed. The most sensitive to heat stress were sows of the duroc breed – fertilization decreased by 25.00 % compared to the pre-stress period, the least – sows of the large white breed – fertilization decreased by 9.82 %. The duration of pregnancy was not affected by heat stress. As well as fertilization, heat stress had a negative effect on the size of the litter. The most sensitive were sows of duroc and MAXGRO breeds – the litter size decreased by 3.77 and 3.61 heads compared to the pre-stress period, the least – sows of the large white breed, the size of the litter decreased by 0.38 heads. duroc sows are the most sensitive to heat stress, then, according to sensitivity reduction, MAXGRO, landrace and large white.