SUMMARYAn experiment was conducted to evaluate productive variables and egg component yields of laying hens in the second productive cycle that were fed a low-protein diet with increasing levels of Thr and Met. A total of 480 hens were assigned to a factorial arrangement of 3 levels of Thr (0.42, 0.48, and 0.54%) and 4 levels of Met (0.19, 0.32, 0.45, and 0.58%). Feed intake was lower (P < 0.01) and FE was greater (P < 0.05) at a dietary Thr level of 0.48%. The eggshell percentage declined linearly (P < 0.01) as the level of dietary Thr increased. Egg production, egg mass, and FE were greater at a Met level of 0.32%, and egg weight was greater when dietary Met was 0.45% (P < 0.01). The BW loss (P < 0.01) and the egg albumen percentage (P < 0.10) declined linearly, whereas the yolk percentage (P < 0.10) and eggshell percentage (P < 0.01) increased linearly as dietary Met increased. For maximum egg production and FE, the Thr intakes were 411.5 and 455.8 mg and the Thr:Lys ratios were 65 and 74%, respectively. With regard to Met, for maximum production and egg weight, the intakes of Met were 313.4 and 343.2 mg and the Met:Lys ratios were 49 and 69%, respectively. The estimated digestible Met requirement per gram of egg mass produced was 6.2 mg.
Three experiments were conducted to evaluate the effects of dexamethasone (DEX) on growth performance and on selected digestive enzyme activities in weanling pigs. In Exp. 1, 96 pigs (6.7 kg BW and 27 d) were used in a 3 x 2 factorial combination of three DEX frequencies (no injection; 1 mg DEX/kg BW 3 d before weaning; and 1 mg DEX/kg BW 6 and 3 d before weaning) and two feeding regimens: a simple diet fed throughout the 28-d trial, or a semicomplex diet fed during the first 14 d postweaning, followed by the simple diet. Growth performance was not affected (P > .10) by hormonal treatment. Pigs fed the simple diet had a greater ADF1 after d 15 postweaning (P < .10) and higher ADG from 15 to 21 d postweaning (P < .01). In Exp. 2, 80 pigs (7.2 kg BW and 26 d) were assigned 3 d before weaning to four dosages of DEX (0, .33, .66, and .99 mg/kg BW). Growth performance was similar regardless of DEX dosing. In Exp. 3, 24 pigs (6.4 kg BW and 21 d) were injected with DEX (1 mg/kg BW) or saline solution on d 3 before weaning. Four pigs per treatment were slaughtered at weaning, or on d 3 and d 6 postweaning. Dexamethasone resulted in greater (P < .10) pancreas weight and increased (P < .01) total activity of amylase and sucrase, but lactase was lowered (P < .10). Dexamethasone injection enhanced digestive enzyme activity but failed to improve performance, presumably because of the reduced feed intake of pigs at weaning.
Two experiments were done to evaluate the effect of increasing levels of dietary digestible methionine (Met) and Met:cysteine (Met:Cys) ratio on the productivity of Hy-Line W-36 laying hens fed sorghum-and soybean meal-based diets. In Exp. 1, 160 hens from 68 to 75 weeks of age were assigned to four dietary levels of digestible Met (0.20 0.24, 0.28 and 0.32%). The digestible total sulfur amino acids:Lysine (TSAA:Lys) ratios were: 62, 68, 76 and 84%. In Exp. 2, 192 hens from 76-83 weeks of age were assigned to four dietary digestible Met:Cys ratios (160, 116.7, 85.7 and 62.5%). The digestible TSAA:Lys ratio was kept constant across diets (80%). Results were subjected to ANOVA and linear regression analyses. In Exp. 1, optimal egg production, egg mass, and feed efficiency responses were observed at 0.30 and 0.50% of dietary digestible Met and TSAA, respectively (quadratic effect, p<0.05). Live performance was maximized with digestible Met and TSAA in takes of 288 and 478 mg/hen/d, respectively. In Exp. 2, optimal egg production and feed efficiency responses were observed at 151 and 150% of dietary digestible Met:Cys ratios, respectively (quadratic effect, p<0.05). The digestible Met, Cys and TSAA intake to maximize egg production and feed efficiency were 313, 207 and 510 mg/hen/d, respectively. The requirements for sulfur AA in Hy-Line W-36 hens from 68 to 83 weeks of age fed sorghum-and soybean meal-based diets fell inside the range of the requirements previously estimated in hens fed corn-soybean meal based diets.
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