PSI-8 - Effect of increasing arginine: Lysine ratio during transition and lactation on farrowing kinetics, milk composition, and sow and litter performance

Abstract: The NRC (2012) requirement estimate suggests the standardized ileal digestible (SID) Arg:Lys ratio for gestating and lactating sows is approximately 52 to 58% while common corn-soybean meal diets result in an SID Arg:Lys ratio of 90 to 100%. While some data suggests benefits of Arg supplementation to sows, research is not consistent and there is limited data available to determine if Arg supplemented immediately prior to parturition and through lactation will benefit sow and litter performance. A total of 90 sows (Line 241, DNA Genetics, Columbus, NE) were used to determine the effect of increasing the SID Arg:Lys ratio in transition and lactation diets on farrowing kinetics, milk composition, and sow and litter performance. Mixed-parity sows were blocked by parity and body weight (BW) on approximately d 108 of gestation and allotted to 1 of 3 dietary treatments of increasing SID Arg:Lys (90, 105, or 120%). Sows received approximately 2.5 kg/d of their treatment diet from d 109 of gestation until farrowing after which they were allowed ad libitum access to their treatment diet. Litters were cross fostered within treatment and within 48 h after farrowing to equalize litter size. SID Arg:Lys did not affect (P > 0.10) sow BW or backfat change during lactation, nor influence sow ADFI either pre farrow or during lactation. Average SID Arg intake increased (linear, P < 0.001) with increasing SID Arg:Lys ratio as expected. No differences were observed (P > 0.10) for the number of total pigs born or for the percentage of total born alive, stillborn and mummified nor did treatment influence litter size, litter weight, or prewean mortality at any time point. On d10, the average BW of piglets tended to be lower in the 120% SID Arg:Lys ratio treatment compared to the 90% SID Arg:Lys ratio treatment (P = 0.061). Piglet ADG from d 1 to 10 tended to be greater in the 90% SID Arg:Lys ratio group compared to the 120% SID Arg:Lys ratio group (P = 0.051), while no differences in piglet performance were observed from d 10 to weaning or birth to weaning. The SID Arg:Lys ratio did not affect (P > 0.10) farrowing duration, colostrum yield, or colostrum intake. Increasing SID Arg:Lys ratio did not affect (P > 0.10) the concentration of IgG in either colostrum and milk and did not impact milk composition or blood urea nitrogen measured in the sow or piglet. Wean to estrus interval decreased then increased (quadratic, P = 0.044) with increasing SID Arg:Lys ratio. This data suggests that increasing SID Arg:Lys ratio from 90 to 120% will not affect farrowing kinetics or sow and litter performance.