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High-yielding lactating sows maintained a high litter growth when fed reduced CP, crystalline amino acid-supplemented diets

Hojgaard, Camilla Kaae, Bruun, Thomas Sønderby, Strathe, Anja Varmløse, Zerrahn, Jens-Erik, Hansen, Christian Fink
Livestock science 2019
Yorkshire (swine breed), analysis of variance, backfat, blood, body weight, creatinine, essential amino acids, fat thickness, free fatty acids, ileum, lactating females, lactose, landraces, litter size, litter weight, milk, milk proteins, piglets, sows, urea nitrogen, weaning
The study was conducted to determine the optimal standardized ileal digestible (SID) CP level to maximize litter gain in high-yielding lactating sows when feeding reduced CP, crystalline amino acid-supplemented. In total, 520 Landrace × Yorkshire sows (parity 1 to 5) were allocated to 1 of 6 diets from day 2 post-partum when litters were standardized to 14 piglets. All diets were formulated to meet or slightly exceed Danish recommendations for Lys, Met, Met + Cys, Thr and Trp using crystalline amino acids. Diets contained 116, 126, 132, 138, 144, and 153 g SID CP per kg (as-fed). Sow body weight, back fat thickness, and litter weight were recorded at litter standardization and at weaning. On a subsample of 72 sows (parity 2 to 4), milk samples were collected at day 3, 10 and 17 post-partum, and blood was sampled at day 10 and 17 post-partum. All data were subjected to ANOVA using the MIXED procedure in SAS. Litter size at weaning was not affected by the dietary CP content (13.0 ± 0.06; P = 0.40), nor was litter ADG (3.13 ± 0.03 kg/d; P = 0.52), nor milk contents of fat and lactose (P > 0.05). Likewise, the daily changes in sow body weight (−0.58 ± 0.04 kg/d, P = 0.44) and back fat thickness (−0.15 ± 0.004 mm/d, P = 0.20) were similar across dietary treatments. Milk protein (P < 0.01), milk Lys (P < 0.05), and other essential amino acids in milk protein were reduced at a SID CP concentration of 116 g/kg. Plasma concentrations of NEFA and creatinine were not affected by dietary treatment (P > 0.05), but concentrations of plasma urea nitrogen were elevated (P < 0.001) as dietary CP content increased. In conclusion, sows were able to maintain a high litter growth when fed reduced CP, crystalline amino acid-supplemented diets. Though, it is not recommended to feed the lactating sows less than 126 g SID CP/kg (as-fed).