15 Young Scholar Presentation: Impact of a Near Ideal Amino Acid Profile on the Efficiency of Nitrogen and Energy Utilization in Lactating Sows

Abstract

Abstract The objective was to determine the efficiency of EAA and energy for lactation in sows and quantify their metabolic heat production fed a reduced protein diet. We hypothesized that feeding a reduced protein diet with near ideal AA profile (NIAA) and a leucine:lysine of 1.14 improves the dietary essential AA (EAA) and energy utilization efficiency and reduces the metabolic heat associated with lactation, compared to feeding diets containing leucine:lysine of 1.63. Three diets were formulated iso-calorically (2,580 kcal/kg net energy), including 1) control diet with a 1.63 leucine:lysine (CON; 18.75% CP), 2) optimal diet with NIAA profile and 1.14 leucine:lysine (OPT; 13.75% CP) by supplementing crystalline AA to minimum requirements; and 3) OPT diet with L-Leucine (Leu) supplementation to achieve CON Leu:Lys of 1.63 (OPTLEU; 14.25% CP). Experiment 1 was to estimate maximal biological efficiency value (MBEV) of EAA in lactating sows fed CON, OPT and OPTLEU diets. Feeding OPT diet improved efficiency of nitrogen (N) (79.1%), arginine (61.1%), His (78.3%), Ile (65.4%), Leu (75.1%), Met + Cys (78.2%), Phe (53.4%), Phe + Tyr (69.5%) and Trp (70.1%) and maximized the efficiency of Lys (63.2%), Met (67.9%), Thr (71.0%) and Val (57.0%) for milk production over a 21-day lactation. Experiment 2 was to estimate dietary energetic efficiency, energy partitioning and heat production in lactating sows fed CON, OPT and OPTLEU diets. Feeding OPT led to greater energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Feeding OPTLEU compared to OPT reduced energy utilization for lactation by directing dietary energy away from the mammary gland and towards maternal pool, in part explaining the efficacy of a NIAA diet over CON. Experiment 3 was to measure heat production in lactating sows fed CON and OPT diets and exposed to thermal neutral and HS environments. Sows fed OPT diet produced less metabolic heat and had lower body temperature when exposed to HS conditions compared to CON fed sows. In conclusion, feeding a diet with NIAA profile containing Leu:Lys of 1.14 improves EAA and energy utilization efficiency for lactation, and reduces the metabolic heat associated with lactation compared to feeding a diet with Leu:Lys of 1.63.