Performance of different broiler genotypes fed diets with varying levels of dietary crude protein and lysine.

Two experiments were conducted to determine if a 3-way interaction among genotype, dietary lysine, and CP is an important influence on dietary responses. The genotypes were Ross 308 and Cobb in experiment 1 and Ross 508 and Arbor Acres Classic in experiment 2. The experimental designs were completely randomized with an incomplete 2 x 2 x 3 factorial arrangement of treatments. On d 7 of experiment 1, 4 replicate pens of 6 chicks each were fed 1 combination of dietary lysine and CP (17% CP with 0.6, 0.7, and 0.8% lysine and 23% CP with 0.7, 0.8, and 0.9% lysine) until d 21. On d 17 of experiment 2, 4 replicate pens of 35 chicks each were fed 1 combination of dietary lysine and CP (17% CP with 0.7, 0.8, and 0.9% lysine and 23% CP with 0.8, 0.9, and 1.0% lysine) until d 42. On d 43 of experiment 2, 3 birds per pen were processed. Regression analysis showed differences (P < 0.05) due to genotype for body weight gain (BWG), feed intake, and feed conversion ratio (FCR) in experiment 1, and BWG, carcass yield, breast fillet and tender yields, and abdominal fat pad percentage in experiment 2. Increasing dietary CP decreased abdominal fat pad percentage in both experiments; however, increasing dietary lysine only decreased this parameter in the starter-phase chicks. In both experiments, Ross broilers had a greater response to supplemental lysine when 17% CP was fed, but less response to supplemental lysine when 23% CP was fed for both BWG and FCR (3-way interaction). Three-way interactions between dietary CP and lysine levels and genotype were observed for BWG (P < 0.01), feed intake (P < 0.01), and FCR (P < 0.02) in experiment 1 and for feed intake (P < 0.06) and FCR (P < 0.03) in experiment 2. The 3-way interactions demonstrate that quantitative differences exist between genotypes in response to increasing dietary levels of CP and lysine.

Economically optimal dietary crude protein and lysine levels for starting broiler chicks.

An experiment was conducted to quantify the growth response of broiler chicks to cumulative dietary lysine and CP intakes. From d 7 to 17, chicks were fed one combination of dietary lysine and CP (17, 20, 23, and 26% CP and 3.5, 4.0, 4.5, and 5.0 g lysine per 100 g of CP) in a diet containing 3,200 kcal/kg ME. There were significant linear and quadratic effects of dietary CP intake and quadratic effects of dietary lysine intake on body weight gain (BWG), confirming that a diminishing response (marginal BWG decreased as intake of dietary lysine increased) existed (R2 = 0.92 and 0.95, respectively). A significant interaction between dietary CP and lysine for BWG complicates economic modeling because responses must be considered together. A quadratic growth response equation describing BWG as a function of dietary lysine and CP intake was used to develop and demonstrate a quadratic programming model. In general, increasing the price of soybean meal (SBM) decreased the dietary CP concentrations that gave maximum BWG and the concentration of dietary lysine decreased proportionally. In SBM-based diets, the concentration of dietary lysine that maximized BWG was less than or equal to the concentration reached by the proportions of corn and SBM needed to meet dietary CP constraints. Savings from using maximum-profit vs. least-cost formulation models could approach 637,000 dollars per year for a single model poultry complex under some economic situations for the starter diet alone.

Comparison of peanut meal and soybean meal as protein supplements for laying hens.

Peanut protein is severely limiting in threonine and has been used to create threonine deficiency in animals. The availability of purified threonine at low cost raises the possibility of economically using peanut meal (PNM) and threonine combinations in poultry diets. An experiment was conducted to compare corn and PNM based diets to corn and soybean meal (SBM) based diets at three protein levels (16, 18.5, and 21%) in diets for 22-to-34-wk-old commercial Leghorns. Birds were housed two per cage with four cages per replicate and six replicates per treatment. Feed consumption, egg production, and feed per dozen eggs were almost identical for PNM (93.8 g/hen per d, 92.2 eggs per 100 hens/d, and 1.22 kg/dozen) and SBM (93.7 g/hen per d, 92.2 eggs per 100 hens/d, and 1.22 kg/dozen). Dietary protein level had no consistent effect on any of these parameters but did significantly improve body weight gains and egg weights (1.2 to 2.5 g/egg). PNM-fed hens laid slightly smaller eggs during the first 6 wk (P<0.05), but there were no egg size differences during the last 6 wk of the experiment (P>0.14). PNM-fed hens laid eggs with better interior quality at 26 and 30 wk of age. After 2 wk of storage, Haugh units remained better for eggs from hens fed PNM than SBM when kept refrigerated (4 degrees C; P<0.05) or at room temperature (20 degrees C; P<0.10). Egg specific gravity was slightly lower for hens fed PNM. It is concluded that PNM is an excellent ingredient for laying hen diets.

The influence of temperature on the threonine and tryptophan requirements of young broiler chicks.

Two experiments were conducted to investigate the influence of a warm environment (35 degrees C) on the threonine and tryptophan requirements of young broiler chicks from 7 to 18 or 21 d of age. Seven hundred forty (experiment 1) and one thousand eight (experiment 2) 1-d-old Cobb x Cobb straight-run broiler chicks were raised in wire-floored battery brooders in moderate temperature rooms (33 to 34 degrees C). For the first 7 d, all chicks were fed a standard corn-soybean-meal-based crumbled starter diet. On d 7, six chicks each (experiment 1) and eight chicks each (experiment 2) were randomly assigned to individual pens. In experiment 1, chicks were fed a corn-peanut meal basal diet supplemented with six levels of threonine (0.630, 0.651, 0.673, 0.715, 0.758, or 0.800% of the diet). In experiment 2, chicks were fed a corn-corn gluten meal based basal diet supplemented with six levels of tryptophan (0.090, 0.115, 0.140, 0.165, 0.190, or 0.215% of the diet). Each dietary treatment was repeated with three pens in each room and three rooms at each temperature. Three rooms were set at a moderate temperature of 25 degrees C, and the other three rooms were set at a warmer temperature of 35 degrees C. Body weight gain, feed consumption, and feed conversion ratio were measured. The threonine requirements of young broiler chicks were 0.733 +/- 0.016% (R2 = 0.59) and 0.752 +/- 0.046% (R2 = 0.25) for body weight gain, and 0.744 +/- 0.016% (R2 = 0.67) and 0.722 +/- 0.016% (R2 = 0.47) for feed conversion ratio at 25 and 35 degrees C, respectively (broken-line linear model). The tryptophan requirements of young broiler chicks were 0.151 +/- 0.004% (R2 = 0.85) and 0.144 +/- 0.003% (R2 = 0.89) for body weight gain, 0.144 +/- 0.003% (R2 = 0.88) and 0.142 +/- 0.003% (R2 = 0.88) for feed consumption, and 0.146 +/- 0.005% (R2 = 0.76) and 0.127 +/- 0.002% (R2 = 0.94) for feed conversion ratio at 25 and 35 degrees C, respectively. On average, the threonine and tryptophan requirements of broiler chicks at 35 degrees C were very similar to those kept at 25 degrees C.

Performance of broiler chicks fed various levels of dietary lysine and crude protein.

An experiment was conducted to establish a basal diet deficient in both protein and lysine. The responses of broiler chicks to graded levels of lysine at two levels of CP were measured in diets mixed by two experimental methods (diet dilution and graded supplementation). Experiment 1 had a 2 x 3 factorial arrangement of treatments with three dietary CP levels (17, 20, and 23%) and two levels of lysine per CP level (35 and 48 g lysine/kg CP). Dietary CP and lysine levels had significant (P < 0.001) effects on body weight gain (BWG), feed intake, and feed conversion ratio (FCR). In exp. 2, the lysine requirement of chicks (9 to 18 d of age) was estimated at two levels of CP in diets mixed by the diet dilution method. The requirements for lysine at 17% CP (as a percentage of CP) were estimated to be 4.45 +/- 0.18% for BWG (R2 = 0.83) and 4.33 +/- 0.16% for FCR (R2 = 0.81). Similarly, the requirements at 23% CP were 4.34 +/- 0.16% for BWG (R2 = 0.84) and 4.35 +/- 0.13% for FCR (R2 = 0.89). In exp. 3, the lysine requirement of chicks (10 to 18 d of age) was estimated at two levels of CP in diets mixed by the graded supplementation method. The requirements for lysine at 18.5% CP were 5.17 +/- 0.25% for BWG (R2 = 0.80) and 4.26 +/- 0.15% for FCR (R2 = 0.85). Similarly, the requirements at 23% CP were 4.59 +/- 0.17% for BWG (R2 = 0.83) and 4.71 +/- 0.16% for FCR (R2 = 0.88). Results of a t-test show that the requirements were not significantly different between the two CP levels for BWG in experiments 2 and 3 (P < 0.05). It is concluded that the amino acid requirements of broilers are a constant proportion of CP levels at least in the range of CP levels commonly fed.

Responses of broiler chickens to cottonseed- and soybean meal-based diets at several protein levels.

Three experiments were conducted to evaluate the performance of broiler chicks fed diets with cottonseed meal (CSM) as the major protein source. Experiment 1 was a 3 x 2 factorial with three crude protein levels (17, 20, and 23%) by two protein sources, CSM or soybean meal (SBM). Diets were fed to male broilers (n = 840) in floor pens from 21 to 49 d of age. L-Lysine-HCl was added to keep lysine at 5.22% of protein. Protein source and level had significant (P < 0.001) effects on BW gain (BWG) and feed conversion ratio (FCR), respectively (no source by level interactions). The average BWG were 1.80, 2.00, and 2.00 kg for birds fed CSM-based diets, compared with 1.93, 2.09, and 2.21 for SBM-based diets (17, 20, and 23% protein, respectively). The average FCR were 2.56, 2.31, and 2.25 for CSM-fed broilers and 2.39, 2.16, and 2.08 for SBM-fed broilers. Significant effects of protein source or level were found for percentage of chilled carcass, fillets, tenders, saddles, and fat pads. In Experiment 2, male broiler chicks (n = 336) were used to determine the lysine requirement of chicks fed a corn and CSM-based diet with 20% CSM and 6% SBM. The basal diet contained by calculation 3,200 kcal/kg of ME, 20% CP, and 0.81% lysine. Graded levels of lysine (0.81 to 1.30% in increments of 0.07%) were fed to chicks from 10 to 20 d, and BW and residual feed were measured at 20 d. The requirement, as determined by breakpoint analysis, was 1.023+/-0.01% lysine (R2 = 0.84) for BWG and 1.028+/-0.02% lysine (R2 = 0.56) for FCR. In Experiment 3, a 2 x 2 x 4 factorial arrangement of treatments involved feeding CSM or SBM to male and female broiler chicks (n = 768) from 21 to 42 d at four dietary protein levels (17, 20, 23, and 26% CP). Lysine was kept at 5.5% of the dietary protein and consisted of the calculated minimum level, established in Experiment 2, plus 7%. Protein level, but not source, had a significant effect on BWG and FCR (P < 0.01 and P < 0.001, respectively) for males. The average BWG were 1.53, 1.74, 1.78, and 1.81 kg for birds fed CSM compared to 1.46, 1.72, 1.84, and 1.82 kg for those fed SBM (17, 20, 23, and 26% CP, respectively); average FCR were 2.36, 2.14, 2.05, and 1.97 for CSM compared to 2.35,2.04, 1.87, and 1.80 for SBM. Protein source and level significantly (P < 0.05) affected feed intake. Significant effects of protein source or level were found for percentage carcass, fillet, tenders, leg quarters, and fat pads. Females had similar qualitative responses. This study showed that at slightly higher protein levels CSM could replace SBM in broiler grower diets to achieve similar performance.

A comparison of eight grades of fat as broiler feed ingredients.

Seven samples of feed- or pet food-grade fats (feed- and pet food-grade poultry greases, restaurant grease, white grease, animal/vegetable oil blend, palm oil, yellow grease) and one food-grade edible fat (soybean oil) were evaluated for quality and fatty acid composition. Active oxygen method (AOM) stability at 20 h ranged from 2 to 370 meq/kg; iodine value from 78 to 130 g/100 g; total moisture, insolubles, and unsaponifiables from 0.46 to 3.33%; initial peroxide values from 0.2 to 18.4 meq/kg; and free fatty acids from 0.08 to 21.0%. The ME of the fats ranged from 7.1 to 12.7 kcal/g and was positively correlated with AOM stability and iodine value. When the fats were incorporated into corn-and-soybean-meal-based diets at 3 or 6%, no differences in live performance due to fat source were observed. Increasing fat level from 3 to 6% decreased feed conversion by 3.4 points (1.628 vs. 1.662 g/g). Feeding feed-grade poultry grease resulted in significantly smaller abdominal fat pads compared to the other fat sources. Only moisture, insolubles, unsaponifiables, and free fatty acids were significantly correlated with performance responses. Differences were noticed in abdominal fat pad color (lightness and redness) due to fat source. Differences in MEn were not reflected in differences in bird performance.