Abstract Practical lactation diets fed to sows in North America are based on corn and soybean meal, with Lysine as the first limiting amino acid. Therefore, the objective of this study was to evaluate the effects of SID lysine level in diets fed to lactating sow, litter and subsequent reproductive performance. Four hundred ninety-five sows were used in a RCBD with blocking factors of day of farrowing, parity, and body condition and allotted to one of three dietary treatments as follows: 1.00% SID Lys (Low Lys), 1.13% SID Lys (Med Lys), or 1.26% SID Lys (High Lys) starting the day of farrowing. Piglets were weighed at birth and at off-test (1 to 3 d prior to weaning). Sow feed intake was recorded using the Gestal lactation feeding system. All piglet deaths were recorded and subsequent reproductive performance data were collected. The study involved 6 turns of the farrowing rooms and data were analyzed using the lmer function of R with dietary treatment as a fixed effect, farrowing turn and parity category (1, 2, 3-6, 7+) as random effects, and individual sow as the experimental unit. There were no differences in total born or litter size after fostering between treatments. Litter birth weight increased linearly (P 0.05) as dietary SID lysine increased; however, there was no difference between treatments in individual piglet weight. There were no differences in days from birth to the piglet off-test or in the number of days of lactation feed records. There was a linear increase (P 0.05) in the number of piglets at off-test and the total litter weight at off-test as SID lysine level in the diet increased. Sow lactation feed intake was similar between treatments. Dietary SID Lysine level had no impact on subsequent reproductive performance measurements. In conclusion, increasing SID lysine in lactation diets linearly improved the number and total litter weight of piglets at off-test, but had minimal impact on other litter or reproductive measures.
Rodriguez et al. (Wed,) studied this question.