Effect of lean growth genotype and dietary XXXX regimen on the lactational performance of sows.

@entity1707 @entity535 @entity4336 @entity376 @entity1460
The effect of dietary @entity535 regimen and genetic capacity for lean tissue growth on the lactational performance of sows was determined in primiparous sows with a high (350 to 390 g/d) or low (240 to 280 g/d) genetic capacity for lean tissue growth from 18 to 110 kg of body weight. During lactation, sows were offered daily 6.5 kg of one of four fortified @entity4336 - @entity1460 meal diets containing .58, .77, .96, and 1.15% @entity376 (L). Litters were standardized to 14 @entity1707 within 8 h after birth. On d 2 of lactation, the high lean growth (LG) sows possessed more proteinaceous tissues and protein and less fat tissue and lipid. During lactation (d 2 to 28 postpartum), high LG sows consumed more feed, mobilized more body protein, and lost less body lipid. Milk, milk energy, and milk @entity376 yields (pooled across dietary regimens) were similar between genotypes. As daily dietary @entity376 intakes increased from 27 to 62 g and total digestible @entity376 supplies (from diet and mobilized tissues) increased from 39 to 68 g, daily yields of milk, milk energy, and milk @entity376 increased, but the magnitude of the response differed (P < .05) between genotypes, evidently because of differences in the ability of the high and low LG sows to mobilize energy from body tissue. Based on these data, the lactational capacities of high and low LG sows nursing 12 to 14 @entity1707 are similar when similar supplies of @entity376 and energy are available from dietary intake and mobilized body tissue stores. When supplies of ME do not limit milk synthesis, daily digestible @entity376 intakes of at least 54 g (> or = 66 g from a @entity4336 -soy diet) are needed by these sows nursing litters of 12 to 14 @entity1707 to support milk synthesis and minimize maternal protein losses. This is equivalent to a total digestible @entity376 need of 4.3 to 4.6 g/kg of milk produced. When ME provided by the diet is less than that needed to fuel maximum milk synthesis, however, the dietary @entity535 needs of genetically lean sows may be reduced because of their inability to mobilize sufficient body fat stores.
