Evaluation of precision feeding standardized ileal digestible lysine and other amino acids to determine and meet the lactating sow's requirement estimates.

Two experiments evaluated the effects of precision feeding standardized ileal digestible (SID) Lys during lactation. Sows were blocked by parity and allotted to treatment on day 2 of lactation. In both experiments, sow body weight (BW), backfat (BF), loin depth (LD), and estimated N excretion were evaluated as well as litter growth performance. In experiment 1, 95 sows and litters were used. Three dietary treatments were provided using 2 diets: a low (0.25% SID Lys) and high Lys diet (1.10% SID Lys). Treatments included a control diet (1.10% SID Lys) fed throughout lactation, and NRC or INRA treatment curves for Lys intake. Sows fed NRC or INRA treatment curves received blends of low and high Lys diets using a computerized lactation feeder (Gestal Quattro Opti Feeder, Jyga Technologies, St-Lambert-de-Lauzon, Quebec, CA) to target a specific Lys intake each day of lactation based on NRC and INRA models for parity and litter size. In experiment 2, 56 sows and litters were used with 3 treatments, a control diet (1.10% SID Lys fed throughout lactation) and either a static or dynamic blend curve. For both curve treatments, low (0.40% SID Lys) and high Lys (1.10% SID Lys) diets were blended to reach target Lys intake. The difference between the static and dynamic curves was that the dynamic curves were adjusted based on actual Lys intake and static curves were not. Lysine intake curves were based on NRC model estimates, but targets were increased by 20% to target average Lys intake of 60 g/d across parities based on results of experiment 1. In both experiments, no differences (P > 0.05) in sow average daily feed intake or sow BW, BF, or LD change were observed. Sows fed the control diets had greater Lys intake (grams per day; P < 0.05) compared to sows fed either of the blended treatment curves. In experiment 1, pigs from sows fed the control diet had greater (P < 0.05) BW at weaning and preweaning average daily gain (ADG) compared to sows fed the INRA treatment curve, with pigs from sows fed the NRC treatment curve intermediate. However, in experiment 2, no differences (P > 0.05) were observed in pig weight at weaning or ADG. In both experiments, sows fed the blended treatment curves had lower (P < 0.05) calculated N excretion. In summary, for a litter size of 13.5 weaned pigs, 60 g/d of SID Lys is sufficient to maximize litter weight gain and can be achieved through blending low and high Lys diets. Precision feeding reduced N excretion compared to feeding a single diet throughout lactation.