Breast Meat Weight Research Articles

Effect of Whole Wheat Dilution on Performance and Carcass Characteristics of Male Turkeys

Field trials and published research suggest that it is possible to dilute commercial turkey and broiler chicken rations with whole wheat and suffer little or no loss in performance. It has been hypothesized that birds fed whole wheat have improved gizzard health and are able to self-select whole grain to better meet their individual nutritional needs. In 6 dietary treatments, the effect of diluting turkey diets with different amounts of whole and pelleted wheat was investigated. In the diets diluted with whole wheat, the whole wheat was blended with the other feed ingredients after they had been steam pelleted. In the diets diluted with pelleted wheat, the extra wheat used to dilute the rations was ground and then blended with the other ingredients prior to pelleting. The influence of adding extra synthetic amino acids to diluted diets was also studied. All diets were supplemented with a commercial feed enzyme. Dilution, without extra synthetic amino acid supplementation, resulted in large reductions in body weight, feed efficiency, and breast meat yield. At the highest level of dilution, where whole wheat dilution was 50% of the diet, body weight and weight of breast meat per bird were reduced by 15 and 20%, respectively. No advantage was observed in diluting with whole wheat compared with pelleted wheat. Addition of extra synthetic amino acids restored 66% of the body weight and 56% of the breast meat lost at the highest level of whole wheat dilution. These results suggest that reports of successful dilution of poultry rations are more likely due to formulation with excess nutrient levels of the undiluted diets rather than to a specific benefit to feeding whole grain.

Threonine Responses of Cobb Male Finishing Broilers in Differing Environmental Conditions

Underfeeding the amino acid Thr may result in suboptimal growth and carcass development, and overfeeding my result in increased diet cost. Adequate knowledge of Thr may be more important in finishing broilers due to increased feed consumption and increased maintenance needs. However, published reports on Thr in the finishing period (d 42 to 56) are few, and recommended requirement estimates vary from 0.60 to 0.75% total Thr. This study was conducted to better understand Thr needs during the 42-to-56-d period in broilers reared in different environmental conditions. Live performance and carcass responses of Cobb male broilers as affected by graduations of Thr were evaluated in clean or dirty floor pen environments. Quadratic responses for live performance and breast meat weight were generated for birds reared in the clean environment and ranged from 0.63 to 0.68% total Thr (0.56 to 0.61% digestible Thr). In contrast, birds reared in the dirty environment responded to Thr in a positive linear manner for live performance and carcass traits. One explanation for birds responding to higher levels of Thr in the dirty environment might have been an increased Thr need for gastrointestinal function.

Dietary Addition of Liquid Saccharopolyspora Solubles Concentrate Positively Affects Pellet Mill Throughput and Broiler Performance

Dietary inclusion of liquid Saccharopolyspora solubles concentrate (SynerMax) is used in the broiler industry to reduce feed milling energy per unit of feed produced and improve feed mill pellet throughput in addition to providing nutrients vital for broiler growth. An experiment was conducted to validate this use by evaluating pellet mill performance responses in corn-and-soybean-meal-based diets containing 0.0, 0.5, 1.0, 2.0, and 4.0% SynerMax. Quadratic response equations indicated that production rate, pellet mill power consumption, and pellet durability index were optimized (100% of asymptote) when diets contained 1.6, 1.2, and 1.3% dietary SynerMax, respectively. In addition to feed mixing improvements, SynerMax contains nutrients that may improve broiler growth and carcass characteristics (i.e., 14.5% crude protein as-is basis, 8.4% crude fat asis basis, amino acids, vitamins, and minerals). Because published reports evaluating the impact of SynerMax on broiler performance are not available, an additional experiment was conducted to evaluate the effect of 0.0, 0.5, and 1.0% dietary SynerMax on male and female broiler growth and carcass responses. Treatment additions of SynerMax were forced-in (0.5 and 1.0%) least-cost formulated diets based on corn, soybean meal, and meat-and-bone meal. Test diets containing SynerMax (0.5 and 1.0%) had marginally reduced levels of corn, soybean meal, and fat as compared to the control test diet (0.0% SynerMax). All diets were formulated to contain 5% meat and bone meal. Male broilers had increased (P < 0.001) BW and decreased (P < 0.001) corrected feed conversion and percentage livability. A SynerMax-by-sex interaction occurred for feed conversion, indicating that male broilers had optimal feed conversion (P < 0.027) when fed diets containing 0.5% SynerMax in comparison to birds fed the control diet. SynerMax did not affect feed conversion in female broilers. As dietary SynerMax was increased, breast meat weight and yield increased in male broilers.

Broiler Performance and Carcass Traits as Affected by Dietary Liquid Saccharopolyspora Solubles Concentrate

No research exists evaluating potential dietary interactions of liquid Saccharopolyspora solubles concentrate (SynerMax) and growth-promoting feed additive compounds. Because SynerMax is currently being used by the poultry industry primarily to improve pellet mill operations, studies were conducted to elucidate possible interactive effects of SynerMax with certain antibiotics (experiment 1) and a probiotic (experiment 2). These experiments utilized rapidly growing broilers of a commercial strain and were carried out in floor pens. The growth-promoting treatments consisted of bacitracin methylene disalicylate (starter and grower diets) and virginiamycin (finisher diet) in experiment 1 and a commercial probiotic in experiment 2. All birds were vaccinated and subsequently challenged with coccidiosis in experiment 2. In experiment 1, the dietary addition of antibiotics decreased (P < 0.05) BW and carcass weight, but birds fed diets containing 0.5% SynerMax had increased (P < 0.05) breast meat yield over birds fed the control diet. In experiment 2, interactions indicated that birds fed the control diet with the probiotic, the 0.5% SynerMax diet with the probiotic, or the 1.0% SynerMax diet without the probiotic had optimal (P < 0.05) BW, corrected feed conversion, carcass weight, and breast meat weight. Dietary SynerMax improved breast meat yield in experiment 1 but not in experiment 2.

Estimativas da composição anatômica da carcaça de frangos de corte com base no nível de proteína da ração e peso da carcaça

Um experimento foi desenvolvido com o objetivo de estimar as proporções dos cortes nobres da carcaça de frangos de corte pelo modelo linear. Foram utilizados 842 frangos machos da linhagem Avian Farms, de 22 a 42 dias de idade, distribuídos num delineamento inteiramente ao acaso em esquema fatorial 3x4. Foram fornecidas rações formuladas à base de milho e farelo de soja para conter 2.900 kcal de EM e 15,43; 17,26; 19,60; e 22,60% de PB; 3.100 kcal de EM e 16,49; 18,45; 20,95; e 24,22% de PB; e 3300 kcal de EM e 17,55; 19,64; 22,30; e 25,78% de PB, totalizando doze tratamentos. Cada tratamento foi constituído por quatro repetições de 18 aves. Fortes correlações foram observadas entre o peso vivo aos 42 dias e o peso da carcaça (r = 0,958), o peso da carcaça e o peso de pernas (r = 0,991), peso de peito+osso+pele (r = 0,965) e peso de peito desossado (r = 0,950). A porcentagem de lipídio foi negativamente correlacionada com a porcentagem de umidade da carcaça (r = -0,880). A equação linear é recomendada para a predição dos componentes anatômicos da carcaça de frangos de corte.

Níveis de Energia e Relações Energia: Proteína para Frangos de Corte de 22 a 42 dias de Idade

Níveis de energia metabolizável (EM) de 2900, 3100 e 3300 kcal e relações energia: proteína (EM: PB) de 128, 148, 168 e 188 kcal/%PB foram avaliados em frangos de corte machos de 22 a 42 dias de idade, distribuídos ao acaso em um esquema fatorial 3 x 4, com quatro repetições de 18 aves por tratamento. O aumento da relação EM: PB apresentou efeito linear decrescente sobre consumo de ração, peso vivo aos 42 dias, ganho de peso, consumo de proteína, consumo de energia metabolizável, peso da carcaça, peso da carne de peito, peso de pernas (coxa+sobrecoxa) e elevou linearmente a porcentagem de gordura abdominal na carcaça em todos os níveis de energia. A relação EM: PB de 148 (20,95% PB) dentro do nível de EM de 3100 kcal atende às exigências de ótimo crescimento de frangos de corte de 22 a 42 dias de idade, enquanto a relação EM: PB de 188 dentro de todos os níveis de energia estudados se mostrou inadequada. Em virtude do aumento do custo da ração, a redução da relação EM: PB, em rações práticas, deve ser avaliada para otimizar o modelo de produção em que a qualidade da carcaça também deve ser considerada.

Ionophore Anticoccidials Fed From Days 56 to 63 and Processing Yields of Male Broiler Chickens

Because some reports have suggested that various anticoccidials may influence carcass composition, male broilers of a commercial strain cross were fed from Days 56 to 63 on nutritionally complete diets containing salinomycin, lasalocid, or monensin. Processing characteristics of these birds were compared to those of birds fed an unmedicated diet. No significant influence of the anticoccidials was observed on dressing percentage, uptake of water in a 12-h static chill bath, or weight or percentage yield of breast meat, leg quarters, wings, or abdominal fat.

Interactive Effects of Lysine and Threonine on Live Performance and Breast Yield in Male Broilers

The TSAA, lysine (Lys), and threonine (Thr) are considered to be the first three limiting amino acids, respectively, in a corn-soybean meal diet fed to broilers. Recent data have clearly demonstrated that feeding broilers diets containing higher than recommended levels of Lys improves broiler performance and edible meat production. In contrast, there is limited data concerning the Thr nutrition of modern broilers selected for breast meat yield. Because essential amino acids are known to interact with one another to improve certain production function, this experiment attempted to describe the relationship between dietary Lys and Thr. This experiment measured the effect of adequate and super-adequate levels of dietary Lys as affected by Thr concentrations ranging from deficient to super-adequate. Increasing the concentration of dietary Lys from 105% to 120% of the NRC recommendation improved body weight gain, feed conversion, carcass yield, breast meat weight, and breast meat yield. Regardless of dietary Lys concentration, increasing dietary Thr from 85% to 92.5% of the NRC recommendation appeared to be adequate for broiler body weight gain and feed conversion. Dietary Lys and Thr interacted on breast meat weight (P<.10) so that 100.0% of the NRC recommendation for Thr was required to maximize breast meat deposition in broilers fed the 105% Lys diets, but 107.5% Thr was necessary to maximize breast meat in broilers fed the 120% Lys diets.

Lysine Level Increases Live Performance and Breast Yield in Male Broilers

Recent data have clearly demonstrated that feeding starting broilers diets containing higher levels of lysine (lys) than recommended by the NRC improves broiler performance. In addition, there are data suggesting the Lys requirement for meat yield is higher than the level considered adequate for feed conversion. Two experiments evaluated the effects of adequate and supplemental Lys levels (93 to 133% of the 1984 NRC for birds 1 to 48 days old in Experiment 1; 97 to 157% of the 1984 NRC for birds 21 to 52 days old in Experiment 2) on broiler performance and carcass muscle development.Body weight was maximized in birds feed 113% of the NRC in Experiment 1 and 109% of the NRC in Experiment 2. Feed conversions were optimized by feeding 103% and 121% of the NRC Lys recommendation in Experiments 1 and 2, respectively. Breast meat weight and proportional yield were significantly increased in Experiment 1, with the greatest improvement achieved by feeding broilers 113% of the NRC Lys recommendation. In Experiment 2, increasing dietary Lys up to 121% of the NRC recommendation significantly increased breast meat weight and proportional yield, with no improvement at higher levels. The results of this study indicate that male broiler performance and breast meat yield are improved by feeding Lys levels well above what is considered adequate by the NRC.

Evaluation of the parameters needed to describe the overall growth, the chemical growth, and the growth of feathers and breast muscles of broilers

An experiment was carried out to collect data suitable for testing methods used to describe the potential growth and body composition curves of broilers. Males and females of two commercial broiler strain-crosses were grown to 16 wk of age with birds taken at 0, 2, 4, 6, 8, 12, and 16 wk of age for chemical analysis and for the measurement of feather weight and breast meat (Pectoralis major and Pectoralis minor) weight at these ages. The data were used to test the Gompertz growth equation and the assumption of chemical allometry, as well as to estimate the values of the growth parameters for the different genotypes. Feeding and environmental conditions were intended to be such that potential growth and body composition could be attained. The weights of the chemical components for each of the four genotypes were described in terms of the mature weight of these components, their rates of maturing, and the time taken to reach the maximum rate of growth of each component. Allometric relationships between the weights of the chemical components and that of body protein were estimated. The ratio of ash to protein was essentially constant. Water matured more slowly, and lipid faster, than protein. For males, and for females up to 8 wk, the models were satisfactory. For females after this age, lipid growth was faster than expected from the earlier period, probably in preparation for egg production. There were small, but important, differences in the values of some parameters between the strain-crosses. For each of the four genotypes the changes in weight of feathers and breast meat with time were described in terms of the Gompertz growth function, which described the data very well. The parameters of the function for each component and genotype-mature weight, rate of maturing, and the time taken to reach the maximum rate of growth B were evaluated. For the feathers, the value of the rate parameter was higher than that estimated for the body as a whole. For the two breast muscles, and for their total weight, the value of the rate parameter was similar to that for the body as a whole. There was a simple allometric relationship between the weights of the breast muscles and that of the whole body. As a consequence, the development of the yield of breast meat for a given genotype could be described by the values of the two parameters: mature yield and the allometric exponent. A description of each genotype of interest is seen as an essential first step in using a simulation model either to predict requirements, or to predict the effects of different feeding programs, and environmental conditions, on the performance of broilers.

Lysine Levels in Starter and Grower-Finisher Diets Affect Broiler Performance and Carcass Traits

Providing adequate dietary lysine (Lys) to broilers is critical if the amount of saleable white meat is the economic objective. However, the period when Lys is most critical for breast development remains unclear. The objective of this study was to determine if dietary Lys in the starter and grower-finisher diets interact to affect live performance, mortality, and breast meat in commercial broilers. This study records two levels of Lys in the starter diets (95 and 115% of 1994 NRC) and three levels of Lys in the grower-finisher diets (85, 105, and 125% of 1994 NRC) fed to male broilers in diets composed of corn, soybean meal, corn gluten meal, poultry meal, and poultry oil.Increasing Lys in the starter or grower-finisher diet increased both performance and mortality. Breast meat weight and yield increased when broilers received the highest Lys levels in the starter and grower-finisher diets. Feeding broilers inadequate dietary Lys in the starter period decreased finishing live performance and breast meat responses, irrespective of grower-finisher Lys levels. Dietary Lys levels above that considered adequate (125% of 1994NRC) in the grower-finisher diets compensated for loss of breast meat due to Lys inadequacy in the starter diet, but compensatory breast meat accretion was not complete.

Genetic analysis of a selection experiment on increased body weight and breast muscle weight as well as on limited abdominal fat weight

1. Genetic parameters of body weight (BW), breast meat weight or yield (BRW, BRY) and abdominal fat weight or yield (FTW, FTY) were estimated in males and females originated from an experimental line selected for improving broiler carcase quality and its control line. 2. Mean heritabilities over both sexes of BW, FTW and FTY were 0.43, 0.56 and 0.63 respectively. Those of BRW and BRY were 0.53 and 0.65 respectively. 3. BW was unfavourably correlated with FTW (rg of 0.40) and to a lesser extent with FTY (rg of 0.12). BW was, as expected, highly correlated with BRW (rg 0.77), but a poor correlation was obtained with BRY (rg of 0.15). Selection for more breast yield should not reduce the leanness of the birds, with a genetic correlation between BRY and FTY of -0.15. 4. The variance explained by the maternal effects accounted for a rather small part of the total phenotypic variance (from 3% to 8% according to the trait), but ignoring these effects led to a significant overestimation of the heritabilities (by 11% to 19%). 5. Except for BRY, the heritability estimates differed between sexes, only moderately for BW but more for BRW, FTW and FTY. However, estimated genetic correlations between sexes were high (between 0.94 and 0.99) and in turn heritabilities of sexual dimorphism of the various traits very low (between 0.02 and 0.07). 6. A significant improvement of the genetic level for growth and carcase composition had been obtained in the selected line, with a mean genetic gain per generation of 0.12 sigma g, 0.13 sigma g and -0.30 sigma g for BW, BRY and FTY respectively.

Lack of interrelationship between the effects of dietary factors and food withdrawal on carcase quality of broiler chickens

1. Four factorial experiments were carried out to determine whether there is any interrelationship between dietary energy-to-protein (E:P) ratio (experiments 1, 2 and 3) or pelleting the diet (experiment 4) and the duration of food withdrawal (FW), in their effect on carcase quality of broiler male chickens. The quality was evaluated by yields of carcase and breast meat, abdominal fat pad size, and the content and composition of the fat in the meat. The effect of sex on the response to FW was also determined in experiment 3 and that of age in experiment 4. 2. The diet with an E:P ratio higher than recommended decreased the weights of carcase and breast meat significantly (P 0.05) in 2 of the 3 experiments, and consistently increased the size of the abdominal fat pad and the fat content in thigh, but not in breast meat. Abdominal fat pad and the fat in meat of birds fed on this diet contained a significantly higher amount of oleic acid and a lower amount of linoleic acid, than the fat of birds fed on the diets with the recommended and the low E:P ratios. The pellets increased significantly the weights of carcase and breast meat and the relative size of abdominal fat pad. 3. FW for 24 h decreased significantly the weight at slaughter in all 4 experiments, carcase weight in 3 experiments, and breast weight in 1 experiment. However, it did not affect the relative size of the abdominal fat pad, the fat content in thigh and breast meat, and the composition of fatty acids in these tissues and in abdominal fat. None of the variables mentioned was affected significantly by the interaction between the dietary factors evaluated, sex or age of the birds on the one hand, and FW on the other hand. 4. It is concluded that the effect of 24 h of FW on weight at slaughter, carcase and breast meat weights and on fattening, is not affected by dietary E:P ratio, pelleting the diet, or sex and age of the broilers.

Research notes: Effect of environmental temperature on broiler chickens subjected to growth restriction at an early age

An experiment was carried out to evaluate the effect of early growth restriction (EGR) induced by feed restriction on the ability of male broiler chickens to withstand exposure to high environmental temperatures. A 2 x 4 factorial arrangement of treatments was employed to determine whether such an exposure affects the beneficial effect of EGR on performance and carcass quality. Chicks consumed feed ad libitum or were feed-restricted from 6 to 12 d of age (to achieve 60% growth of the ad libitum birds). From 4 to 8 wk of age, the chickens were kept in temperature-controlled chambers at 25, 30, 35 C and a diurnal cyclic temperature of 25:35 C. Weight gain, feed intake, and feed efficiency from 6 to 8 wk of age (after acclimatization to the various temperatures) and BW at 8 wk of age were significantly (P < or = 0.05) depressed by the high temperatures (35 and 25:35 C) compared with values observed at 25 and 30 C. Early growth restriction did not affect these variables. Relative heart, liver, and breast meat weights at 8 wk of age were decreased significantly with increasing temperature. Relative liver weight was also decreased significantly in the EGR chicks, whereas breast yield was increased significantly in these birds. Relative abdominal fat pad size was not affected by increasing the temperature from 25 to 35 C, but it was significantly lower in chickens kept at 25:35 C than in those kept at 25 and 35 C. Early growth restriction significantly reduced the size of abdominal fat. Because no significant interactions between EGR and ambient temperature on the above mentioned variables were observed during 4 to 8 wk of age, it is concluded that EGR can not alleviate the adverse effect of high ambient temperature on performance, nor can high ambient temperature obliterate the beneficial effect of EGR in improving feed efficiency and reducing fattening.

Effect of Supplementing Nonessential Amino Acids on Growth Performance and Fat Accumulation in Broiler Chicks Fed a Diet Supplemented with Met+Cys.

The present study was conducted to determine the effects of glycine (Gly) or glutamic acid (Glu) on growth performance, weights of breast meat and abdominal fat, and various lipid fraction contents in the liver, serum and breast meat of chicks fed a diet supplemented with DL-methionine (Met) plus L-cystine (Cys). The basal diet containing sulfur amino acids (0.64% of diet) was supplemented with Met plus Cys at 1.25% of diet (diet A). The diet A was supplemented with either glycine (diet A+Gly) or glutamic acid (diet A+Glu) at 5g/kg diet. Body weight and breast meat weight were significantly heavier in chicks fed the diet A+Gly than those fed the basal diet. Chicks fed the diet A+Glu increased feed efficiency compared with those fed the basal diet and diet A. The feed intake was significantly lower for chicks fed the diet A+Glu than for those fed the diet A+Gly. The addition of Met+Cys to the basal diet resulted in decrease in abdominal fat weight. Moreover, abdominal fat weight was lower in chicks fed the diet A+Glu than those fed the diet A alone. Met+Cys (diet A) results in the reduction of triglyceride contents in the liver and breast meat compared to the basal diet. Gly (diet A+Gly) could decrease the liver triglyceride content, while Glu (diet A+Glu) gave rise to an increase in it in comparison to the basal diet or the diet A. However, phospholipid content in the serum and breast meat of chicks fed Glu (diet A+Glu) was significantly lower than those fed Gly (diet A+Gly).

The Effect of Supplementing Cystine on the Growth Performance and Liver Lipid and Phospholipid Contents of Broiler Chicks.

This experiment was conducted to determine the effect of dietary cystine (Cys) on the growth performance and the liver lipid and phospholipid of broiler chicks. Basal diet containing 23% CP (TSAA=0.69%) was supplemented with Cys at 0.098, 0.163, 0.238, and 0.324%. Cystine supplementation resulted in significantly (P<0.05) heavier body weights. However, the growth response was not linear nor directly proportional to the level of Cys supplementation. Dietary Cys improve growth but failed to affect abdominal fat and breast meat weights. Cys caused the significantly increase in fatty liver score and liver lipid but a decrease in liver phospholipid. It is clear that Cys resulted in the increase in liver weight. There were positive relationship between liver weight and fatty liver score, and between fatty liver score and liver lipid content.

Broiler Response to Energy or Energy and Protein Dilution in the Finisher Diet

Two experiments were carried out with male broiler chickens in which diets from 35 to 49 d of age were diluted by oat hulls and sand. In one experiment only energy was diluted; in the second experiment, both energy and protein (amino acid) levels were affected. Each diet was tested with four replicate floor pens each containing 25 1-d-old birds. All birds received a standard starter diet to 16 d and then grower diet to 35 d.In Experiment 1, dilution of only energy resulted in a significant linear (P < 0.01) reduction in body weight at 42 d, although there was growth compensation after this time such that all birds weighed the same at 49 d. Diet energy dilution resulted in increased feed intake, although energy intake was not maintained (P < 0.01). Diet energy dilution generally had little effect on carcass weight or yield of breast meat, although there was less abdominal fat (P < 0.01). In Experiment 2, dilution of both energy and protein had a comparable effect on growth rate as described in Experiment 1; however, in this study there was a linear decrease in carcass weight and breast meat yield as the diet was diluted. These results suggest that the male broiler chicken can grow quite well on very low energy diets but that a period of at least 7 d is required for adjustment to feed intake. Even with compensatory increase in feed intake, however, the bird is unable to maintain its energy intake when fed such diluted diets.

Effects of Dietary Protein Under High Ambient Temperature on Body Weight, Breast Meat Yield, and Abdominal Fat Deposition of Broiler Stocks Differing in Growth Rate and Fatness

The effect of dietary protein on growth, feed intake and efficiency, abdominal fat deposition, and breast meat yield was investigated in broiler males from a commercial stock (WI) and from experimental stocks selected for low (LF) or high (HF) abdominal fat. All birds were kept at constant high ambient temperature (32 C) and were provided with low- (LP) or high-protein (HP) diets from hatch until 8 wk of age (Experiment 1) or from 4 to 8 wk of age (Experiment 2). In both experiments, HP diet significantly increased 4- to 8-wk BW gain in the LF and HF stocks but reduced it in the WI stock as compared with the LP diet. Abdominal fat, as percentage of BW, was almost twofold higher in the HF birds than in the LF ones, with WI mean being intermediate. In contrast to the HF and WI birds, in which abdominal fat decreased with increased protein intake, abdominal fat was not affected by dietary protein in the LF stock. The HP diet substantially increased breast meat yield in LF birds but not in the WI birds, with HF birds exhibiting intermediate increase in breast meat weight. It was concluded that birds of varied inherent growth rate and tendencies toward protein and fat deposition respond differently to dietary protein level under heat stress.

Lack of Interactions Between Dietary Lysine or Strain Cross and Photoschedule for Male Broiler Performance and Carcass Yield ,

The purpose of this study was to test interactions of dietary lysine or strain crosses provided increased lysine with photoschedule on broiler performance and carcass quality. In Experiment 1, treatments were factorially arranged as two lysine levels [control grower and finisher (NRC, 1984) or control grower and finisher plus .15% L-lysine HCl] and two photoschedules [23 h light (L):1 h dark (D) or 14L:10D]. All birds received a control starter feed and dietary treatments were initiated at 22 d of age. In Experiment 2, treatments were factorially arranged as two strain crosses [Peterson × Arbor Acres (PAA) or Ross × Ross (RR)] and two photoschedules (23L or 16L). All birds received standard starter and standard grower and finisher plus .15% L-lysine HCl. There were no lysine by photoschedule or strain cross by photoschedule interactions in this study. The high-lysine diet increased BW, improved feed efficiency, increased lean carcass weight and yield of breast meat, and decreased abdominal fat and yield of thighs. The PAA strain cross had better feed conversion, fewer Grade A carcasses, more back bruises and breast blisters, greater yield of wings and drumsticks, and less yield of breast meat than RR. The 23L had greater BW, better feed efficiency, fewer breast blisters, greater carcass weight (Experiment 1), more abdominal fat (Experiment 2), lower yield of wings (Experiment 1), drumsticks, and thighs, and greater yield of breast meat than the treatments with shorter photoschedules. Increased dietary lysine did not compensate for decreased breast meat yield associated with 14L (Experiment 1).

Influence of Metabolizable Energy Feeding Sequence and Dietary Protein on Performance and Selected Carcass Traits of Tom Turkeys

Two identically designed experiments were done to determine the effects of reducing dietary MEn concentration during late growth and of dietary protein concentration on performance and selected carcass traits of turkey toms. A complete factorial arrangement of three MEn feeding sequences and four dietary protein concentrations was used. The MEn feeding sequences were 102% of MEn concentrations listed by NRC (1984), from 1 to 119 days of age (M), 102% MEn for 1 to 42 days followed by 108% MEn from 42 to 119 days (M-H), and the same as the M-H sequence except the 102% MEn diets were fed from 105 to 119 days (M-H-M). The four dietary protein concentrations were 93, 100, and 107%, of NRC recommended protein concentrations, in which essential amino acid (EAA) levels met or exceeded NRC recommendations, and 107% of NRC, in which the EAA concentrations were at least 107% of NRC recommendations. Feeding diets of the M-H and M-H-M MEn sequence improved feed efficiency (P ≤ .01) in both experiments as compared with the M sequence. Toms fed the M-H or M-H-M sequences in Experiment 1, but not in Experiment 2, were heavier at the finish than those fed the M sequence. Body fat of toms was increased (P < .05) by feeding the M-H MEn sequence, compared with feeding the M or M-H-M sequences in Experiment 1. No dietary MEn effects on body fat were observed in Experiment 2. Dietary protein concentration did not modify the effects of MEn feeding sequence and there were no effects of protein concentration on BW or feed efficiency in either experiment. Fat pad and breast meat weights were affected differently by dietary treatments in the two experiments, possibly because of differences in ambient temperature during the last 3 to 4 wk of the experiments.