Response of two strains of large white male turkeys to amino acid levels when diets are changed at three- or four-week intervals

Effects of decreases in the three most limiting amino acids of low protein diets at two different feeding periods in Japanese quails

1. Diets containing 100 (AA100), 95 (AA95), 90 (AA90) or 85% (AA85) of National Research Council (NRC, 1994) recommendations of methionine, threonine and lysine in a low-protein diet (200 g/kg) were fed to 15-d-old quails. 2. Decreases of up to 15% of NRC recommendations in these three amino acids did not affect feed intake, weight gain and gain:feed intake values in the 15-35- and 15-42-d feeding periods. 3. Compared to control diet, feeding cost per bird was lower in males fed with AA95 and AA85 at 15-35 d and with AA85 diets at 15-42 d. At 15-35 d, feeding cost per 100 g weight gain was lower in both males and females receiving the AA85 diet while at 15-42 d it was lower in males fed with AA85 and females fed with AA90 compared to the control diet. Feeding cost calculated based on 100 g weight gain resulted in more meaningful results than cost calculated for the production of a bird. 4. Dietary amino acid content did not significantly affect carcase, thigh (bone in and skin on) or breast meat (deboned and skin on) yields. Males fed with AA90 diet and females fed with AA90 and AA85 had lower protein contents in their breast meat (without bone and skin) compared to the ones fed with control diet.

Growth performance and carcass characteristics of female turkeys as affected by feeding programs

A trial was conducted to evaluate the effects of different feeding programs on growth performance and carcass characteristics of Nicholas Large White female turkeys. Three different feeding programs were considered for a 12-wk period: 1) 3 diets fed for 4 wk each (starter 24% CP, grower 20% CP, and finisher diet 16% CP), 2) 2 diets fed for 6 wk each (starter-grower 22% CP and grower-finisher diet 18% CP), and 3) no change of diet for 12 wk (starter-grower-finisher diet 20% CP). From 0 to 4 wk of age, birds were fed an ad libitum common starter diet. Each dietary treatment was replicated 3 times, and feed and water were provided ad libitum. Body weight and feed consumption were measured every 2 wk, whereas carcass characteristics were evaluated at 16 wk of age. Feed intake increased as the frequency of dietary changes decreased, and feed conversion was not different between programs 1 and 3. There were no significant differences in final BW among experimental groups. For a single feeding program, the proportion of neck, bone, and feet decreased, and a greater percentage of edible meat was registered as compared with the other 2 groups. Mean carcass, breast, and thigh weights of turkeys reared under multiple diets were not different compared with other groups. Positive correlations were noted between live weight and weight of carcass, breast, thigh, drumstick, wing, and abdominal fat of turkeys. Thus, a single cycle feeding regimen in Nicholas Large White female turkeys results in similar growth performance and carcass characteristics compared with other conventional feeding programs considered in the present study.

Effect of amino acid formulation and amino acid supplementation on performance and nitrogen excretion in turkey toms

A 2 x 2 factorial experiment was conducted to determine whether diets formulated with 2 (Lys and Met) or 3 (Lys, Met, and Thr) supplemental AA to 100 or 110% of NRC (1994) amino acid (AA) recommendations would affect performance and N excretion of turkey toms. Diets were formulated with corn, soybean meal (SBM), and 6% meat and bone meal. Diets were formulated to maximize SBM inclusion when formulated with 2 supplemental AA, thereby resulting in 2.0, 1.5, 1.4, and 1.0% units more CP than diets containing 3 supplemental AA at 4 to 8, 8 to 12, 12 to 16, and 16 to 20 wk of age, respectively. Each diet was fed to 12 replicate pens of birds with 10 birds per pen. Body weight, feed intake, and feed/gain was not affected by AA formulation or AA supplementation (average 20-wk BW = 20.7 kg). Similarly, the weight of the pectoralis major at 20 wk of age was not different between birds fed different diet regimens. Nitrogen intake was affected by diet with birds fed 100% NRC AA consuming 144 g (7.3%) less N, with $0.48 less feed cost/20-wk tom, than those fed 110% NRC AA. Similarly, birds fed 3 vs. 2 supplemental AA consumed 154 g less feed N (8.4%) with $0.37 less feed cost/20-wk tom to 20 wk of age. These differences in N intake resulted in 0.8 kg more N in litter/pen (7%; P = 0.067) in birds fed 100% NRC AA vs. those fed 110% NRC. Similarly, birds fed 3 vs. 2 supplemental AA had 1.24 less N in litter/pen (10.8%). These data suggest that diets containing AA formulations above NRC (1994) recommendations do not provide any additional performance or pectoralis major yield benefits, yet results in considerable increases in excreted N. In addition, formulation with 3 supplemental AA results in a sizeable reduction in N consumed and excreted.

Dietary arginine and lysine in Large White toms. 1. Increasing arginine:lysine ratios does not improve performance when lysine levels are adequate

A study was conducted utilizing two strains of male Large White turkeys (BUT Big 6 and Nicholas 700) to determine the effects of increasing Arg:Lys ratios on live performance and carcass composition. Diets were formulated to provide 100, 110, and 120% of NRC (1994) Lys levels, adjusted for dietary energy level, with Arg:Lys ratios of 1.0:1, 1.1:1, 1.2:1, and 1.3:1 in a 3 x 4 factorial arrangement. Eight pens of 15 poults (four pens of each strain) were fed each of the 12 test diets for an 18-wk period. Diets were changed at 3-wk intervals rather than the 4-wk interval suggested by NRC. The results of this study suggest that the Arg and Lys levels suggested by the NRC (1994) are not sufficient when diets are fed on 3-wk intervals, rather than the 4-wk intervals suggested by NRC. This conclusion is in agreement with the studies of Waldroup et al. (1997b). Increasing Arg:Lys ratios improved performance of turkeys only when the diets contained insufficient amounts of Arg in association with low levels of Lys. Increasing Arg:Lys ratios when diets contained sufficient amounts of these two amino acids was without benefit, in contrast to the report of Brake et al. (1994). Turkeys of the BUT Big 6 strain appeared to be more sensitive to marginal deficiencies of Lys and Arg than did turkeys of Nicholas 700 strain.

Effects of amino acid restriction during starter and grower periods on subsequent performance and incidence of leg disorders in two strains of male large white turkeys

Male turkeys of two commercial Large White strains (Nicholas 88, BUT 6) were subjected to growth restriction by means of reducing amino acid (AA) content of diets to a minimum of 75% of NRC (1994) suggested levels. There were three periods when diets containing 75% of NRC recommended AA for that age period were fed ad libitum: 0 to 3 wk, 0 to 6 wk, or 6 to 12 wk. A fourth (control) group was not restricted in AA content at any time. When turkeys were not fed the AA-restricted diets they were fed diets formulated to meet a minimum of 100, 110, or 120% of NRC (1994) AA recommendations, which resulted in a 3 x 4 factorial arrangement of treatments with three AA levels by four restriction times. Four pens of 12 males each were fed each AA by restriction time combination. At 18 wk, all birds were scored individually for leg condition and representative samples of turkeys were processed for parts yield. Birds fed restricted diets from 0 to 6 or 6 to 12 wk had significantly lower BW at 18 wk than control birds. Birds fed the restricted diets from 0 to 3 wk did not differ significantly in 18-wk BW compared to control birds but the magnitude of difference was similar to that observed at the end of the restriction period. Feed utilization was not improved by early AA restriction. Restricting early growth resulted in a significantly higher incidence of birds with no leg disorders and a lower incidence of birds with moderate leg disorders than control birds. Feeding higher AA levels during realimentation resulted in a greater severity of leg disorders. Breast meat yield was depressed significantly as severity of early restriction increased. Increasing dietary AA above NRC (1994) recommended levels generally improved performance during realimentation but was not able to compensate for reduced gains during restriction.