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The objective of this study was to evaluate targeted maternal weight gains in sows by parity group during gestation. Weight and backfat gains during gestation by parity, weight, and backfat groups also were analyzed. The data evaluated were a subset (374 sows) of a larger experiment that compared three methods of feeding sows during gestation on weight and backfat gains and subsequent reproductive performance. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gains. Actual backfat gain for gilts and sows was regressed on maternal weight gain and estimated energy available for gain. The regression equations were then used to predict maternal weight gains for target backfat gains for three parity groups (gilts, Parity 1 and 2 sows, and Parity 3 and older sows). For gilts and Parity 1 and 2 sows, much greater target maternal weight gains are required to achieve 6 and 9 mm of backfat gain, whereas Parity 3 and older sows require maternal weight gains similar to those targeted to achieve the desired backfat gain. Given similar energy intake levels above maintenance, gilts gained more weight than multiparous sows, as gain was based more on protein and less on fat and thus was more efficient. Gilts required more maternal weight gain than sows to achieve similar backfat gains due to the higher protein and low fat contents of gain in younger, lighter sows compared with older parity sows. Low-backfat sows that needed to gain large amounts of backfat failed to achieve these large gains. We speculate this failure may be due to lower tissue insulation levels with the low backfat levels and higher activity levels of these sows compared with high-backfat sows. It seems that both parity and weight are individually important factors that influence energy and nutrient requirements for gestation in the modern sow. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate targeted maternal weight gains in sows by parity group during gestation. Weight and backfat gains during gestation by parity, weight, and backfat groups also were analyzed. The data evaluated were a subset (374 sows) of a larger experiment that compared three methods of feeding sows during gestation on weight and backfat gains and subsequent reproductive performance. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gains. Actual backfat gain for gilts and sows was regressed on maternal weight gain and estimated energy available for gain. The regression equations were then used to predict maternal weight gains for target backfat gains for three parity groups (gilts, Parity 1 and 2 sows, and Parity 3 and older sows). For gilts and Parity 1 and 2 sows, much greater target maternal weight gains are required to achieve 6 and 9 mm of backfat gain, whereas Parity 3 and older sows require maternal weight gains similar to those targeted to achieve the desired backfat gain. Given similar energy intake levels above maintenance, gilts gained more weight than multiparous sows, as gain was based more on protein and less on fat and thus was more efficient. Gilts required more maternal weight gain than sows to achieve similar backfat gains due to the higher protein and low fat contents of gain in younger, lighter sows compared with older parity sows. Low-backfat sows that needed to gain large amounts of backfat failed to achieve these large gains. We speculate this failure may be due to lower tissue insulation levels with the low backfat levels and higher activity levels of these sows compared with high-backfat sows. It seems that both parity and weight are individually important factors that influence energy and nutrient requirements for gestation in the modern sow. [ABSTRACT FROM AUTHOR]

Lysine is the first limiting amino acid in practical swine diets, so it is important to optimize the dietary digestible lysine to maximize growth and profitability. Two experiments were conducted to estimate the standardized ileal digestible (SID) Lys requirement for pigs from 25- to 50-kg BW (Exp. 1) and 50- to 75-kg BW (Exp. 2) using ADG and G:F as criteria responses. A total of 1050 barrows and gilts (FAST Fl female x PIC380 boar line) were used in each experiment, blocked by gender, with 10 pens per treatment and 21 pigs per pen. Experimental diets were formulated to contain 2.3 Meal NE/ kg and to meet or exceed all nutrient requirements except Lys, according to NRC (2012). Minimum ratios of 30% Met:Lys, 60% Met+Cys:Lys, 21% Trp:Lys, 70% VakLys, 55% Ile:Lys, and 102% Leu:Lys on a SID basis were used for all diets. The SID ThnLys ratio was 65 and 66% for Exp. 1 and 2, respectively. In Exp. 1, pigs were fed diets formulated to contain 0.72, 0.80, 0.88, 0.96 or 1.04% SID Lys whereas in Exp. 2 diets were formulated to contain 0.68,0.75, 0.82,0.89 or 0.96% SID Lys. Responses measured at the pen level were analyzed using general linear and nonlinear heteroskedastic mixed models. Dose response curves were evaluated using linear (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ) models. For each response variable, the best-fitting model was selected using Bayesian information criterion. Gender was used as covariate when significant. Increasing SID Lys content in the diet quadratically (P < 0.01) increased ADG and G:F in Exp. 1 and linearly (P < 0.001) increased ADG and G:F in Exp. 2. From 25- to 50-kg, the best-fitting models for ADG and G:F were the LM and QP, respectively, with the maximum response estimated at > 1.04% SID Lys. From 50- to 75- kg BW, the best-fitting model for ADG was the BLQ estimating the requirement at 0.83% (95% confidence interval [CI]: [0.80%, 0.86%]) SID Lys, with 99% of maximum achieved with 0.82%. For G:F, the BLL was the best-fitting model and the SID Lys requirement estimated at 0.85% (95% CI: [0.75%, 0.94%]) with 99% of maximum achieved with 0.80%. In conclusion, the SID Lys requirement for 25- to 75-kg pigs may be higher than the recommendation from NRC (2012). [ABSTRACT FROM AUTHOR]