Effects of increasing SID lysine and metabolizable energy levels in lactation diets fed to young and mature sows.

The objective was to evaluate increasing standard ileal digestible (SID) lysine (Lys) and metabolizable energy (ME) above recommended inclusion levels fed to young (parity 1-2) and mature (parity 3-5) lactating sows. A total of 741 sows (371 parity 1-2, 370 parity 3-5) were fed in a 2×2 factorial arrangement of treatments in a randomized complete block design. Factors included SID Lys (0.85% vs 1.11%) and ME (3.18 Mcal/kg vs 3.33 Mcal/kg). Diets were formulated to deliver 62 g of SID Lys at 0.85% inclusion and 23.2 Mcal of energy to sows that consume 7.30 kg of complete feed per day. Overall, sows consumed 61 g/d SID Lys and 22.6 Mcal/kg, but because of nutrient intake differences between young and mature sows, outcome variables were analyzed separately and not statistically compared. There were no differences for either SID Lysine or ME treatment in lactation feed intake (P ≥ 0.27) or change in body weight (P ≥ 0.19) for young sows. Young sows fed 3.33 Mcal/kg ME had 0.31 fewer post-cross foster mortalities (P < 0.01) resulting in weaned litters that were 4.06 kg heavier (P < 0.01) than litters from young sows fed 3.18 Mcal/kg ME. Young sows fed 1.11% SID Lys and 3.33 Mcal/kg ME had the fewest (P ≤ 0.03) sows bred by d 7 compared to all other treatments. There was an interaction (P = 0.03) for wean-to-estrus-interval for young sows were young sows fed 1.11% SID Lys and 3.33 Mcal/kg ME were at least 3.27 days longer than young sows fed 0.85% SID Lys and 3.33 Mcal/kg ME or 1.11% SID Lys and 3.18 Mcal/kg ME. Young sows fed 3.33 Mcal/kg ME had a nearly 7% improvement in lactation G:F (0.40 vs 0.43; P < 0.01) compared to young sows fed 3.18 Mcal/kg ME. The percentage of mature sows fed 1.11% SID Lys bred by day 7 was 7.0 percentage units less (P = 0.06) when fed 3.33 Mcal/kg ME compared to 3.18 Mcal/kg ME. Feed efficiency of mature sows fed 1.11% SID Lys (0.38) was 7.89% greater (P < 0.01) than mature sows fed 0.85% SID Lys (0.35). Increasing either SID Lys or ME energy to young and mature sows had little influence on sow or pig performance, but simultaneously increasing both SID Lys and metabolizable energy negatively impacted subsequent breeding performance.