Variability in gestating sows’ nutrient requirements

In practice, sows often receive the same diet during the gestation even though their nutrient requirements vary over gestation and among individuals. The objective of this study, realized within the Horizon 2020 EU Feed-a-Gene program (grant agreement n°633531), was to report the variability in nutrient requirements among sows and over time, in order to develop a precision feeding approach. A dataset of 2,511 gestations reporting sows’ characteristics at insemination and farrowing performance was used as an input for a Python model based in InraPorc® predicting nutrient requirements over gestation. The influence of parity (P1, P2, P3+), litter size, and week of gestation on metabolizable energy (ME), SID lysine (Lys) and threonine (Thr), digestible phosphorus (dP) and total calcium (Ca) requirements was analysed using a mixed model with R software. Total ME requirement increased with increasing litter size, with week of gestation, and with parity (30.6 vs 35.5 MJ/d for P1 and P3+). Lys and Thr requirements per kg diet increased from week 1 to week 6, remained stable from week 7 to 10, and increased again from week 11 until the end of gestation. Lys and Thr requirements increased with increasing litter size and decreased when parity increased (Lys: 4.04 vs 3.09 g/kg for P1 and P3+; Thr: 3.06 vs 2.49 g/kg for P1 and P3+). dP and Ca requirements increased markedly after week 9, increased with litter size, and decreased when parity increased (dP: 1.36 vs 1.31 g/kg for P1 and P3+; Ca: 4.28 vs 4.10 g/kg for P1 and P3+). Based on empiricalcumulative distribution functions, a strategy with 4 diets, varying in Lys and dP content with parity and gestation week (before B or after A week 11), can be suggested to achieve the requirements of 90% of the sows (two diets for multiparous sows: B: 3.2 g Lys/kg and 1.1 g dP/kg; A: 4.9 g Lys/kg and 2.3 g dP/kg; and two diets for primiparous sows: B: 3.8 g Lys/kg and 1.1 g dP/kg; diet A: 5.5 g Lys/kg, 2.2 g dP/kg). Better considering the high variability of sows’ requirements in practice should thus allow optimizing their performance whilst reducing feeding cost. A first step can be achieved by grouping and feeding sows by week of gestation and parity, and a second step by feeding the sows individually.