Significant mammary development occurs during late gestation in sows, which is necessary to support milk production in the ensuing lactation period. Gilts (first-parity sows) have not achieved mature body weight and are developing mammary tissue for the first time. Thus, gilts may benefit from additional amino acid supply during late gestation to support both fetal growth and mammary development, as well as their own growth.
Earlier work found that feeding gilts 40% more standardized ileal digestible lysine (SID Lys), via soybean meal, beyond the recommended 18.6 g/day, improved mammary development by 44%, though subsequent milk production was not assessed.
Vanessa Kloostra and Dr. Lee-Anne Huber from the University of Guelph and Dr. Chantal Farmer from Agriculture and Agri-Food Canada aimed to determine the level of additional standardized ileal digestible lysine (SID Lys), provided through soybean meal in late gestation, to maximize piglet birth weight and subsequent milk production by first-parity sows.
In the current study, 152 first-parity sows were enrolled beginning on day 90 of gestation and followed through weaning. Seven treatment diets were formulated to provide: 70%, 85%, 100%, 115%, 130%, 145% and 160% of the NRC- (2012) estimated SID Lys requirements via the addition of soybean meal. Sows were fed 2.65 kg/day of their assigned gestation diet from day 90 of gestations until farrowing. After farrowing, all sows received a standard lactation diet.
Body weight was recorded on days 90 and 110 of gestation, within 24 hours of farrowing, and at weaning (day 20 of lactation). Sow receiving higher levels of SID Lys (protein) gained more weight during gestation. However, these same sows also tended to lose more weight during the ensuing lactation period.
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