Performance and carcass composition of large white toms as affected by dietary crude protein and threonine supplements

The response of turkeys to dietary balanced protein during two periods of growth

1. Two experiments were conducted to measure the response of growing turkeys to dietary protein content. In the first, 960 sexed British United Turkey (BUT 6) poults were used to measure the response to balanced protein from 3 to 6 weeks of age. In the second, 1440 sexed BUT and Hybrid Converter poults were raised from 14 to 17 weeks.2. In both experiments, six levels of dietary protein were fed, with feed intake, body and feather weight gain and changes in body composition measured. The levels of protein chosen ranged from 0.53 to 1.2 of the Aviagen requirements for growing turkeys.3. In the first experiment, six poults were sampled from each sex at the start of the experiment for carcass analysis, and four were sampled from each strain and sex in the second. At the end of each experiment, eight poults from each treatment were sampled. Body composition analyses were made on individual defeathered birds.4. Weight gain increased linearly with protein intake in the early period and exponentially in the later period. In both periods, feed intake decreased as protein content reduced.5. In the early period, body lipid content increased from 20.2 to 41.5 g/kg body weight, as dietary protein content decreased, but there was no change in the later period. Efficiency of utilisation of dietary protein declined linearly with an increase in dietary protein content, from 0.87 to 0.46 g/g in the first, and from 0.43 to 0.27 g/g in the later period.6. The inability of the growing turkey to increase feed intake on marginally limiting feeds may have been due to a genetic constraints to store excess energy consumed as body lipid, resulting in the observed decrease in feed intake as dietary protein content is reduced.

Effects of Enriched Charcoal as Permanent 0.2% Feed-Additive in Standard and Low-Protein Diets of Male Fattening Turkeys: An On-Farm Study

Wet litter is the most important cause of footpad dermatitis in poultry, this in turn being a highly relevant animal-related welfare indicator. This field study was subdivided into two experiments. In Experiment 1, the standard diet was supplemented by 0.2% enriched charcoal, being a non-specific absorber and therefore might be promising in reducing faecal moisture. In Experiment 2, the experimental group received a reduced crude protein diet during weeks 6-13, combined with a 0.2% enriched charcoal supplementation. The trials were each conducted with two batches on three farms under on-farm conditions. The animals were observed at 6, 10, 14 and 18 weeks of age to collect data on body weight and different health parameters. The mortality and litter samples were analysed after slaughtering. In Experiment 1, performance and health were not affected despite higher dry matter content of the litter. In Experiment 2, the weight of birds receiving the protein-reduced diet was decreased significantly throughout the experiment. However, the slaughter weight did not differ. The mortality was reduced by 0.5% in the experimental group. Therefore, it was concluded that 0.2% of enriched charcoal is not a valuable feed-additive regarding animal health, while temporary protein reduction might have positive effects.

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.

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.

Decreasing broiler crude protein requirement by methionine supplementation

The experiment was conducted with two levels of protein (23 and 20% in starter, 20 and 18% in grower) and three levels of methionine (NRC, 110 of NRC and 120% of NRC in starter and grower stages). No significant differences were found for protein, methionine or their interaction on Feed Intake (FI) and Feed Conversion Ration (FCR) for starter and grower, with the exception of an interaction of 20% CP and 0.46% (120% ofNRC) methionine which significantly improved (p < 0.05) the FCR compared with 18% CP and 0.38% (NRC) level ofmethionone, at the grower stage. Carcass yield and breast meat were significantly (p < 0.05) increased by 23% Crude Protein (CP) compared to 20% in starter. In contrast, abdominal fat was significantly decreased (p < 0.05) by 23 and 20% CP diet in starter and grower, respectively compared to the other levels of CP as well as by high levels of methionine. In the interaction of 20% CP and high level of methionine (0.46%) on carcass yield, a significant increase (p < 0.05) was found in grower stage compared with 18% CP and both 0.38% and 0.42% (110% of NRC) of methionine levels. A similar effect was found on breast meat yield compared with interaction of both 0.5% (NRC) and 0.55% (110% of NRC) of methionine and 20% CP at 21 days, as well as at 42 days of age with 0.38% methionine and 18% CP. Finally, the results of this study, have suggested that methionine/CP ratio could be adjusted at 0.024% (0.024 g methionine/per g crude protein) in starter and 0.023% for grower. Decreased CP in the diet, increased breast meat yield and reduction of abdominal fat were achieved by these ratios of methionine/protein.

Limiting amino acids after methionine and lysine with growing turkeys fed low-protein diets

The effectiveness of Thr and other amino acids (AA) replacing CP in Met- and Lys-adequate diets of Large White male turkeys was studied from 6 wk to market age. Experiment (EXP) 1 examined efficacy of Thr and an AA grouping in corn-soybean (CS) diets containing 82.8 and 77.0% of NRC CP and in corn-soybean-canola-meat (CSCM) diets containing 85.2 and 79.4% of NRC (1984) CP. Experiment 2 compared AA responses in CSCM diets containing 100, 92.5, 85, and 77.5% of NRC (1994) CP. Compared with control CP, 1) 92.5% of NRC CP supported maximum BW, and supplemental Thr or Trp was without effect; 2) 82.8 to 85.2% of NRC CP resulted in reduced BW and breast meat yield (BMY), and supplemental Thr or Trp was ineffective in reversing this reduction, and 3) 77 to 79% of NRC CP resulted in depressed BW and BMY. Supplemental Thr provided a substantial positive BW but no BMY response, whereas a combination of Thr, Ile, Val, Arg, and Trp completely returned BW and partially returned BMY to that of the normal CP control. Turkeys on CS and CSCM assay diet series supported BW responses to CP and AA similarly. We concluded that in low-CP diets containing Met and Lys to requirement, supplemental Thr resulted in improved BW, whereas Thr, Ile, Val, Trp, and Arg returned BW, but not BMY, to normal CP control.

Identification of limiting amino acids in methionine- and lysine-supplemented low-protein diets for turkeys

Large White male turkeys were fed 100, 85, 70, or 60% of NRC (1994) CP during 7 to 28 d (Experiment (EXP) 1), 8 to 12 wk (EXP 2), and 16 to 20 wk (EXP 3) of age. Diets contained corn, soybean, canola, and meat meals and were supplemented with Met and Lys to requirement. The influence of supplementary amino acids (AA) was studied at each protein level. Turkeys fed 85% CP gained BW similarly to those fed 100% of NRC CP (control) during each age range. Supplemental Thr, Val, and Ile during 7 to 28 d or 8 to 12 wk, or Thr during 16 to 20 wk, did not result in positive BW gain response. For turkeys fed 70% CP, BW gain was depressed compared with the normal-CP control in each period. During 7 to 28 d and 8 to 12 wk of age, the combination of Thr, Ile, Val, Arg, and Trp to 100% of NRC reversed the BW depression; here only Thr, Ile, and Val were essential components of the response. The BW depression during 16 to 20 wk was reversed by the combination of Thr, Ile, Val, and Trp. For turkeys fed 60% of CP, BW gain was severely depressed. The combination of Thr, Ile, Val, Trp, and Arg resulted in nearly complete BW recovery during each age.

Dietary threonine responses in growing turkey toms

A study was conducted to evaluate Thr responses in Large White (British United Turkeys) male turkeys during three time periods: 0 to 3, 3 to 6, and 6 to 9 wk of age. The Thr-deficient diets, fed in 3-wk intervals, were composed primarily of corn, peanut meal, poultry meal, and soybean meal as intact protein sources and supplemented with amino acids. Graded levels of L-Thr were added to the Thr-deficient diets. Another group of turkeys received a corn-soybean-poultry meal control diet in each time period. Diets were formulated to meet a minimum of 110% of suggested amino acid specifications (NRC, 1994) for all essential amino acids, except Thr. Feed intake, BW gain, and feed:gain responses were measured. Average environmental temperatures for Weeks 1, 2, and 3 were 29, 27, and 24 C, respectively. From 4 to 9 wk of age, average environmental temperatures varied between 24 and 35 C. Turkeys in each time period responded to Thr in a curvilinear manner with responses at the asymptote being equivalent to turkeys fed the corn-soybean meal control diets. Adequate dietary Thr levels for gain and feed:gain for the 0 to 3 wk period were 0.93% (3.21 g Thr/Mcal ME) and 0.97% (3.34 g Thr/Mcal ME) of diet, respectively. From 3 to 6 wk of age, the level of dietary Thr needed to support adequate BW gain and feed:gain was 0.88% of diet (2.81 g Thr/Mcal ME). The level of dietary Thr needed to support adequate BW gain and feed:gain from 6 to 9 wk of age was 0.77% of diet (2.30 g Thr/Mcal ME). These results indicate that the NRC (1994) estimations of Thr needs up to 9 wk of age are more than adequate.