PSXII-31 Effect of dietary protein level and amino acid balance on heat production in lactating sows exposed to thermal neutral and heat stress conditions.

摘要

The study objective was to measure total heat production (THP) of multiparous lactating sows (n=12) with their nursing litters, allotted to two diets under two environmental temperatures. Sows were either fed a diet containing 19.60% CP (CON) or a reduced CP diet containing 14.22% CP and crystalline AA (OPT). Both diets had the same SID Lys (0.90%) and NE (2,580 kcal/kg). Sows were either housed under thermal neutral (TN, 21 ± 1.5°C) or cycling heat stress conditions (HS, 24 ± 1.5°C for nighttime and 32 ± 1.5°C for daytime). Positive pressure indirect calorimeters were used for measuring gas exchange in individual sows and litters on d 4, 8, 14, and 18 of lactation. Sow and litter weights were recorded on d 1, 10 and 21 to calculate THP. Total heat production of the sow and litter was determined for 12 h during the nighttime (24°C; 1900-0700 h) and for 12 h during the daytime (32°C; 0700-1900 h). Compared to control, THP of sows fed OPT did not differ under TN or HS environments. During the daytime, compared to sows and litters exposed to TN, sows and litters exposed to HS produced less heat on d 8 of lactation (7.49 vs. 8.43 kcal/h·kg ; < 0.05), and tended to produce less heat on d 14 (8.88 vs. 9.64 kcal/h·kg ; = 0.099) and 18 (8.72 vs. 9.64 kcal/h·kg ; = 0.092). Total heat production changed ( < 0.01) as lactation progressed on d 4, 8, 14, 18 (7.39, 7.96, 9.26, 9.18 kcal/h·kg , respectively), appearing to peak between d 14 and 18. To conclude, feeding a reduced CP diet to lactating sows does not decrease sow and litter THP when housed under TN or HS conditions, and exposure to HS conditions reduced THP compared to TN conditions.