The effect of dietary protein level on milk yield and composition and piglet growth and composition of the Meishan synthetic and European White breeds of sow

Abstract

AbstractCurrent feeding recommendations for lactating sows may be inappropriate for modern genotypes with high milk production. The introduction of the prolific but obese Meishan breed into sow lines also necessitates a review of nutrient requirements. A 2 × 2 factorial experiment was used to investigate the influence of breed type (Meishan synthetic 50% (M) and purebred European White (W) on response to dietary protein level (L = 140 g crude protein (CP) per kg, 6 g lysine per kg; H = 181 g CP per kg, 9 g lysine per kg) over a 5-week lactation. Milk yield (days 5, 9, 13,17, 21 and 28), milk composition and piglet growth and body composition were measured to quantify aspects of lactational performance. M had higher litter sizes throughout lactation (P < 0·001) and produced more milk than W(M = 10·04 W = 7·85 (s.e.d. 0·521) kg/day, P < 0·001) and milk of a higher fat content (M = 79·6 W = 75·0 (s.e.d. 5·71 g/kg, P < 0·05). Total solids were not significantly different between treatments. H produced higher milk protein content than L (L = 43·0 H = 55·7 (s.e.d. 3.01) g/kg, P = 0·05). Litter growth rates showed a breed effect (P < 0·001), diet effect (P < 0·001) and a breed × diet interaction (ML = 2·41 MH = 3·21 WL = 2·07 WH = 2·07 (s.e.d. 0·658) kg/day, P < 0·001). M piglets had higher fat deposition rates (M = 37 W = 24 (s.e.d. 4.5) g/day, P < 0·05). L piglets had a lower protein (P < 0·05) and fat (P < 0·05) deposition rate compared with H piglets. Higher litter growth rates of M sows resulted from a combination of increased milk yield and f at content and this was further enhanced by additional dietary protein. W sows showed no milk yield response to dietary protein but reduced maternal tissue catabolism.