Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigates heat production associated with milk for lactating sows

Authors: ZHANG, SAI - Michigan State University; Johnson, Jay; QIAO, M - Hubei Academy Of Agricultural Sciences; TROTTIER, NATHALIE - Michigan State University

Submitted to: Journal of Animal Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2019
Publication Date: 2/7/2020
Publication URL: https://handle.nal.usda.gov/10113/6833525
Citation: Zhang, S., Johnson, J.S., Qiao, M., Trottier, N.L. 2020. Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigates heat production associated with milk for lactating sows. Journal of Animal Science and Biotechnology. https://doi.org/10.1186/s40104-019-0414-x.
DOI: https://doi.org/10.1186/s40104-019-0414-x

Interpretive Summary: Larger litter sizes and higher litter growth potential have increased lactation demands on the sow. In addition, lactation is an energetically costly process that relies on the sows’ ability to consume enough dietary energy to sustain milk production. Unfortunately, sow feed intake remains limited due to environmental stressors such as heat stress. Therefore, dietary strategies to improve energetic use efficiency for lactation are needed to improve sow feed energy intake and milk production for piglets. The study objective was to evaluate the effects of reducing dietary crude protein to increase dietary energy efficiency, partitioning of energy to milk production, and reduce metabolic heat production. It was determined that feeding diets to sows with near ideal amino acid profiles improved the use of energy for milk production in sows and resulted in less energy being partitioned towards metabolic heat production and urine output. In addition, supplementing leucine above the requirements of the sows decreased energy use for milk production. These data have positive implications towards altering sow diets to improve productivity and welfare under stressful conditions.

Technical Abstract: The goal of the study was to test the hypothesis that 1) lowering dietary crude protein (CP) would increase dietary energetic efficiency, energy partitioning and reduces metabolic heat for lactation, and2) excessive dietary Leu supplementation in the reduced protein diet would reduce dietary energetic efficiency, energy partitioning and increase metabolic heat for lactation. Fifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets (2,580 kcal/kg NE): 1) Control (CON; 18.75% CP), 2) reduced CP with optimal AA profile (OPT; 13.75% CP) and 3) Diet OPT with excessive Leu (OPTLEU; 14.25% CP). The CON was formulated based on corn and soybean meal as the only Lys sources to satisfy Lys requirement. The OPT was low protein diets with crystalline amino acids (CAA), meeting essential AA requirement. Supplemental Leu was added to OPT to create OPTLEU and match the same Leu level in CON. Sow body weight and backfat were recorded on d 1 and d 21 of lactation and piglets were weighed on d 1, 4, 8, 14, 18, and 21 of lactation. Energy balance was measured on sows during early (d 4 - 8) and peak (d 14 -18) lactation, and milk was sampled at the end of each balance (i.e., d 8 and 18). Body weight loss and body lipid mobilization differed from 0 (P < 0.05) in sows fed OPT. In peak lactation, sows fed OPT had higher milk energy secretion (P < 0.05) than CON. Sows fed OPTLEU tended to (P = 0.07) secrete less milk energy than OPT butdid not differ from CON.. Total energy retention did not differ across all diets. Maternal energy retention was lower (P < 0.05) in OPT and OPTLEU compared to CON sows, but did not differ between OPTLEU and OPT sows. Milk N output relative to ME intake tended to be higher (P = 0.088) for in OPT versus CON sows. Sows fed OPT had higher (P < 0.05) apparent energy efficiency for milk production compared to CON.. The ME/DE tended to be higher (P = 0.063) in OPT versus CON sows. The NEmilk/ME and NElactation /ME was higher (P < 0.01) or tended to be higher (P = 0.092), respectively, in OPT compared to CON sows. Heat production associated with lactation was lower (P < 0.05) or tended to be lower (P = 0.082), respectively, in OPT and OPTLEU compared to CON sows. To summarize, the OPT diet improved dietary 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 energy mobilization. Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk, partially explaining the effectiveness of NIAA diet over conventional diets.