Heat stress refers to the sum of the non-specific physiological responses of the body to the thermal environment in extreme high-temperature environments. With the development of intensive, high-density feeding methods, heat stress has led to a decline in sow fertility.
Heat stress causes severe sow weight loss, prolonged interval between weaning and re-estrus, decreased ovulation number, decreased fertility rate, decreased embryonic survival rate, reduced number of litters in litters, no estrus in sows, and may even reduce the use of sows. Years of age. In addition, underfeed intake during lactating sows during heat stress results in insufficient milk production, thus affecting piglet growth and pre-weaning survival.
Provides quality protein
Proteins and lysine in lactating sows' diets are key factors affecting their reproductive performance. Low lactation dietary protein prolongs the interval between weaning and re-estrus. Under heat stress, the protein requirement of the pig increases, but if the crude protein is too high, the body heat of the sow is increased and the sow feels hotter. Therefore, when the weather is hot, providing lactating sows with quality protein and supplementing essential amino acids can effectively meet their needs and reduce weight loss.
The daily lysine requirement for lactating sows should exceed 60 grams, and the corresponding feed lysine content can be calculated based on the actual sow feed intake. Threonine is not enough to produce milk and breast growth. Therefore, threonine is a potentially critical limiting amino acid for sows with low feed intake and high body weight loss.
During a 21-day lactation period, the ratio of threonine to lysine in feed should be increased to 75% for sows with a body weight loss of 75-80 kg. For sows with the smallest body weight loss (0–8 kg), the ratio of threonine to lysine in feed can be reduced to 60%. For sows fed a typical corn-soybean meal diet, threonine may be the first limiting amino acid when the weight loss is the largest (75-85 kg), but in the case of other weight loss, the The amino acid may still be the first limiting amino acid; when the weight loss is minimal, proline may become the second limiting amino acid following lysine. It has been reported that increasing the arginine level in diets from heat-stressed sows from 0.96% to 1.73% can reduce the weight loss of sows and increase feed efficiency, but there is no effect on sow feed intake and piglet growth performance. Significantly affected. (Wang Yan, Animal Husbandry Bureau, Zhaoyuan City, Shandong Province)
Increase lactation dietary energy concentration
When the sow's dietary energy concentration is increased, sows' feed intake tends to decrease, and the final energy intake is similar. However, when using high-fat diets, sows’ energy intake generally participates. According to the principle of thermodynamics, under high temperature conditions, body heating can lead to a decrease in feed intake. In contrast to carbohydrates and proteins, the heat consumption of fat is reduced and the energy content is high. Therefore, increasing the energy concentration by adding fat to the diet is more advantageous for the hot emergency nursing sow. Feeding high-fat diets to heat-stressed sows can reduce the interval between weaning and re-estrus in sows. The composition of short-chain fatty acids in breast milk does not use saturated fatty acids and long-chain fatty acids in contrast to excessive oils. In addition, in the summer, it is necessary to prevent the added fat from being oxidized or rancid. It is recommended that antioxidants be added at the same time.
In addition to the occurrence of heat stress, it is not appropriate to add fat to the sow's diet because fat does not produce a starch-like effect that promotes insulin secretion. In contrast, the addition of fat to lactating sows diets reduced plasma insulin levels and luteinizing hormone secretion.
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