The effects of energy and amino acid levels on performance and carcass quality of male and female broilers grown separately

Sex-specific genetic parameter estimates of body weight in Mazandaran indigenous chickens

Body weight is an economically important trait in poultry that shows sexual dimorphism (SD). In the present study, variation in SD in Mazandaran native chickens was investigated in terms of the (Co) variance components and genetic parameters of body weight between males and females. Studied traits were body weights at hatch (BW1), 8 weeks (BW8) and 12 weeks of age (BW12). Also, for weight at sexual maturity (WSM) covariance components were only estimated in females. Cross-sex direct and maternal correlations were also estimated for studied traits except for WSM. For this purpose, a deep 21-generation pedigree and body weight data (57,576 BW1, 72,925 BW8, 62,727 BW12 and, 42,496 WSM) were used. Evaluation of SD of body weight was performed using six bivariate animal models with and without considering the genetic and permanent maternal environmental effects under the restricted maximum likelihood method in WOMBAT software. Model with direct additive genetic effects and maternal genetic effects without covariance between them was identified as the best model for BW1 and BW8. The Model including direct additive genetic effects and permanent maternal environmental effects was the best model for BW12 and WSM. Direct heritability (h2) estimates for BW1, BW8 and, BW12 were, respectively, 0.05 ± 0.013, 0.17 ± 0.02 and, 0.25 ± 0.03 in males and, 0.05 ± 0.012, 0.15 ± 0.01 and 0.21 ± 0.01 in females. Also, the direct heritability of WSM based on univariate analysis in females was estimated to be 0.40 ± 0.01. Maternal heritability (h m 2 ) varied from 0.39 ± 0.01 (BW1) to 0.04 ± 0.009 (BW8) in males, and 0.36 ± 0.10 (BW1) to 0.04 ± 0.006 (BW8) in females. The correlation between direct genetic effects between males and females for BW1 was not significantly different from one. The direct genetic correlation between the two sexes for BW8 and BW12 was significantly different from 1 concluding that these traits are dimorphic in terms of direct genetic effects and therefore independent selection in both sexes is possible.

Characterization of growth patterns and carcass characteristics of male and female broilers from four commercial strains fed high or low density diets

Over the last few decades, the poultry industry has seen the emergence of various market segments that are beneficial for rearing various flock sizes. Two concurrent experiments consisting of 1,200 broilers each were conducted to evaluate the effects of broiler size and diet on the performance of four commercially available broiler strains, including 2 standard yielding (SY) and 2 high yielding (HY) strains. Within each experiment (Experiment 1: males, Experiment 2: females), a small bird (38 and 40 d processing) and big bird (47 and 54 d processing) debone market were targeted to give variable carcass size. Two polyphasic diets were fed based on varying of amino acid densities. The low-density diet (L) consisted of 1.20, 1.10, 1.00, and 0.96% digestible Lys and the high-density diet (H) consisted of 1.32, 1.21, 1.10, and 1.06% across the 4-phases, respectively, with similar essential amino acid to digestible Lys ratios between the L and H diets in each phase. Weekly BW, BW gain, feed intake, and feed conversion ratio were assessed, as well as processing yields during both experiments. Broilers fed the H diets responded better than those fed the L diets, regardless of sex, with increased BW and decreased FCR (P < 0.05). Male HY strains provided the highest carcass yields (P < 0.05) compared to SY strains, with no differences observed in females (P > 0.05). High density diets (Diet H) also produced increases in carcass, breast, and tender yield (P < 0.05) for males, but that trend was not present in carcass yield for females (P < 0.05). Overall, strain impacted performance traits and carcass yields. Therefore, the use of specific strains and amino acid density for various market segments is beneficial for integrators to maximize return.

Determining the 4th limiting amino acid in low crude protein diets for male and female Cobb MV × 500 broilers

1. Four experiments were conducted to determine the 4th limiting amino acid (AA) in maize-soybean meal-based diets. 2. Deletion assay methodology was used to quantify performance and carcase trait responses to potential deficiencies in essential and conditionally essential AA caused by reductions in dietary crude protein of maize-soybean meal-based diets from 202.9 to 186.5 g/kg. 3. The deletion of Val, Phe and Gly + Pro resulted in negative effects on live performance and carcase traits for male broilers, whereas AA deletion only affected wing weights for females with no response on live performance. 4. Further experimentation could not duplicate a response to Phe or Pro in male broilers. 5. Valine was identified as the potential 4th limiting AA in maize-soybean meal-based diets and was not found to be co-limiting with Ile.

Impacts of Graded Levels of Metabolizable Energy on Growth Performance and Carcass Characteristics of Slow-Growing Yellow-Feathered Male Chickens

A dose-response study was conducted to investigate the metabolizable energy (ME) requirement for Lingnan chickens from 9 to 15 weeks of age. One thousand two hundred 8-week-old slow-growing yellow-feathered male chickens were allotted to five dietary ME levels (2805, 2897, 2997, 3095 and 3236 kcal/kg). The results revealed that the daily metabolizable energy intake increased (p < 0.01), whereas the feed intake and feed:gain ratio decreased linearly (p < 0.01) with the increment in dietary ME level. The final body weight and daily gain of the highest ME treatment tended (p > 0.05) to be greater than those obtained with the lower ME levels. The fat content in breast muscle showed a quadratic response (p < 0.05) to the increase in dietary energy level. The shear force values of breast muscle in the 2897, 3095 and 3236 kcal/kg treatments were lower (p < 0.05) than those of the 2997 kcal/kg treatment. In conclusion, among the tested ME levels, 3095 kcal/kg was adequate for feed intake, shear force, and plasma uric acid, and 3236 kcal/kg tended to increase the body weight, body gain, and feed conversion ratio of Lingnan males between 9 and 15 weeks of age; further studies are still required for testing higher levels.

Effect of diets with different energy concentrations on growth performance, carcass characteristics and meat chemical composition of broiler chickens in dry tropics

Background

Diets with increasing levels of energy were fed for 42 days to 200, 1-day old male broiler chickens to evaluate growth performance, carcass characteristics and chemical composition of meat. The study was performed in the subtropical area of northeastern Mexico. Treatments diets (T) for starter and finisher phases had apparent metabolizable energy (AME; kcal/kg) of: 2960 and 3040 (T1); 3000 and 3080 (T2); 3040 and 3120 (T3); 3080 and 3160 (T4), respectively. Within each of the growing phases the four treatment diets were formulated to contain similar levels of crude protein, amino acids, and other nutrients. In a completely randomized design, birds were allocated to the four treatments with five replicates (floor pens) of 10 birds each. The trial was divided in two phases (starter and finisher) of 21 days each (42 days total).

Results

Weight gain was not influenced by energy level; however, feed conversion efficiency was improved in the diets with 3040 and 3120 kcal/kg AME (T3; P < 0.05). There was no influence of treatment on total carcass weight or carcass cuts (P > 0.05). Meat from breast muscle had similar crude protein percentages among treatments; ether extract was higher in T1 than T4 (P < 0.05). The percentages of water, ether extract, ash and crude protein in thigh meat were not significantly different (P > 0.05) among treatments.

Conclusions

For this study carried out in a dry tropical area, the moderate increase in dietary energy concentration (diet with 3040 and 3120 kcal/kg AME, T3) enhanced feed conversion efficiency of broiler chickens.

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.

Determination of the best level of dietary energy with two diet formulation methods based on total and digestible amino acid on broiler diet

In order to evaluate the effects of different levels of energy and methods of formulation of Amino Acid (AA) requirements of diets, this experiment was conducted using 392 broiler chicks. The experiment was carried out using a complete randomize block design with 7 levels of energy 3175, 3075, 2975, 2875, 2775, 2675 and 2575 kcal kg(-1) for grower diet and 3225, 3125, 3025, 2925, 2825, 2725 and 2625 kcal kg(-1) for finisher diet and two methods of formulation of diets AA requirements (total and digestible) as a factorial arrangement. Results showed that by increasing level of energy feed intake, body weight and FCR were promoted in grower diet (p<0.05). Effect of decreasing level of energy up to 2725 and 2825 kcal kg(-1) was not significant on body weight and FCR in finisher diet, respectively. Formulating of diet based on total or digestible AA affected feed intake and FCR in finisher diet (p<0.05). Interaction effect of independent factors affected on body weight in grower diet (p<0.05). Decreasing level of energy increased gastrointestinal tract percentage weight (p<0.05). Formulation of diet based on digestible AA decreased gastrointestinal tract percentage weight (p<0.05). Abdominal fat decreased significantly as ME content of diets decreased. Results showed that it's possible to reduce the level of energy up to 3175 kcal kg(-1) in grower and 2725 kcal kg(-1) in finisher diet for giving the best and economical performance response. Formulation of diet based on digestible AA in finisher diet resulted in promotion of performance.

Effect of Varying Metabolizable Energy and Crude Protein Concentrations in Diets of Pearl Gray Guinea Fowl Pullets 1. Growth Performance

This study was undertaken to assess dietary ME and CP concentrations for optimum growth performance of Pearl Gray guinea fowl pullets. In a 3 x 3 factorial arrangement, 540 one-day-old Pearl Gray guinea keets were randomly assigned to experimental diets with 2,900, 3,000, and 3,100 kcal of ME/kg of diet, each containing 20, 22, and 24% CP, respectively, from 0 to 8 wk of age (WOA). From 9 to 16 WOA, these diets were adjusted to contain 3,000, 3,100, and 3,200 kcal of ME/ kg, and each had 17, 19, and 21% CP, respectively. Each dietary treatment was replicated 4 times, and feed and water were provided ad libitum. Body weight and feed consumption were measured weekly. Mortality was recorded as it occurred. Overall, feed consumption was higher in birds on 2,900 and 3,000 kcal of ME/kg of feed and the 24 and 21% CP diets than other dietary treatments at 0 to 8 and 9 to 16 WOA, respectively. When compared with other dietary treatments, cumulative BW gains were higher (P < 0.05) in birds fed 3,000, 3,000 and 3,100, and 3,100 and 3,200 kcal of ME/kg of diet at 2 to 5, 6 to 8, and 9 to 16 WOA, respectively. Pullets receiving 24 and 21% CP diets also exhibited higher BW gains than other dietary treatments at 0 to 8 and 9 to 16 WOA, respectively. Feed conversion ratios were lower (P < 0.05) in birds fed 3,000, 3,100, and both 3,100 and 3,200 kcal of ME/kg of diet at 1 to 5, 6 to 8, and 9 to 16 WOA, respectively, than other dietary treatments. Pullets fed 24% CP diets and either 17 or 19% CP diets exhibited lower (P < 0.05) feed conversion ratios than other dietary treatments at 1 to 8 and 9 to 16 WOA, respectively. Thus, diets comprising 3,000 and 3,100 kcal of ME/kg were utilized more efficiently by the Pearl Gray guinea fowl pullets at 0 to 5 and 5 to 16 WOA, respectively. Also, these birds more efficiently utilized diets containing 24 and 17% CP at 0 to 8 and 9 to 16 WOA, respectively.

Effects of dietary metabolizable energy and crude protein concentrations on growth performance and carcass characteristics of French guinea broilers

This study was undertaken to assess dietary CP and ME concentrations for optimum growth performance and carcass characteristics of French guinea broilers. In a 3 x 3 factorial arrangement, 396 1-d-old French guinea keets were randomly assigned to experimental diets with 3,050, 3,100, and 3,150 kcal of ME/kg of diet; each contained 21, 23, and 25% CP, respectively, from 0 to 4 wk of age (WOA). From 5 to 8 WOA, experimental diets had 3,100, 3,150, and 3,200 kcal of ME/kg of diet, and each contained 19, 21, and 23% CP, respectively. Each dietary treatment was replicated 3 times, and feed and water were provided ad libitum. Body weight and feed consumption were measured weekly, whereas carcass characteristics were evaluated at 8 WOA. For the most part, birds on 3,100 and 3,150 kcal of ME/kg of diet at 0 to 4 WOA exhibited greater (P < 0.05) BW gain, greater carcass and breast weights (P < 0.05), and lower (P < 0.05) feed consumption and feed conversion ratios (FCR) than those on a diet with 3,050 kcal of ME/kg. Mean feed consumption of birds fed 25% CP diets was higher (P < 0.05) than those on other dietary CP concentrations. Mean BW gain, FCR, and carcass and breast weights of birds fed 25 and 23% CP diets from 0 to 4 WOA were not different (P > 0.05), but they were better (P < 0.05) than those of birds on 21% CP diets. Positive correlations (P < 0.01) were noted between live weight and weight of carcass, breast, thigh, drumstick, and wing of guinea broilers. Thus, diets with 3,100 kcal of ME/kg and 23% CP or with 3,150 kcal of ME/kg and 21% CP at 0 to 4 WOA and 5 to 8 WOA, respectively, were used more efficiently by French guinea broilers.

Use of nonlinear programming to optimize performance response to energy density in broiler feed formulation

A nonlinear programming optimization model was developed to maximize margin over feed cost in broiler feed formulation and is described in this paper. The model identifies the optimal feed mix that maximizes profit margin. Optimum metabolizable energy level and performance were found by using Excel Solver nonlinear programming. Data from an energy density study with broilers were fitted to quadratic equations to express weight gain, feed consumption, and the objective function income over feed cost in terms of energy density. Nutrient:energy ratio constraints were transformed into equivalent linear constraints. National Research Council nutrient requirements and feeding program were used for examining changes in variables. The nonlinear programming feed formulation method was used to illustrate the effects of changes in different variables on the optimum energy density, performance, and profitability and was compared with conventional linear programming. To demonstrate the capabilities of the model, I determined the impact of variation in prices. Prices for broiler, corn, fish meal, and soybean meal were increased and decreased by 25%. Formulations were identical in all other respects. Energy density, margin, and diet cost changed compared with conventional linear programming formulation. This study suggests that nonlinear programming can be more useful than conventional linear programming to optimize performance response to energy density in broiler feed formulation because an energy level does not need to be set.

Influência do Genótipo e do Sexo Sobre o Valor Hematócrito em Galinhas Reprodutoras Pesadas

Este trabalho avaliou o efeito do genótipo e do sexo sobre os valores de hematócrito em galinhas para corte. Foram utilizados 180 reprodutores, provenientes de 18 genótipos experimentais, dos quais amostras de sangue foram coletadas para determinação da porcentagem de células sanguíneas. Para o fator genótipo foi possível distinguir dois grupos, com médias variando de 45,83 a 41,69% e 41,24 a 37,21%. Já para o fator sexo, os valores apresentaram diferença significativa, com valores de 46,20 ± 4,14% para machos e 35,74% ± 3,16% para fêmeas. Concluiu-se que o genótipo e o sexo influenciaram o valor hematócrito em galinhas reprodutoras pesadas, além de agrupar todos os genótipos em dois grupos.

Efeitos de Diferentes Programas de Alimentação sobre a Ocorrência da Síndrome Ascítica em Frangos de Corte

Foi estudado, para frangos de corte, mediante a utilização de 3 programas de alimentação (3, 4 e 5 fases de arraçoamento), com níveis nutricionais diferenciados, a ocorrência de ascite , sendo que machos e fêmeas foram criados separadamente durante a época do inverno. Utilizou-se 6 repetições por tratamento, sendo 40 aves por repetição. Avaliou-se o desempenho e a mortalidade (total e por ascite), além de se verificar hipertrofia do ventrículo direito e alteração do hematócrito. Não se obteve diferença significativa apenas para os valores do hematócrito, no entanto, melhores resultados foram atingidos na criação de machos em relação às fêmeas (p<0.05) para peso das aves, consumo de ração e peso dos ventrículos (VD e VT). Obteve-se correlação positiva entre a proporção dos ventrículos e a ocorrência de mortalidade por ascite. Verificou-se também que a mortalidade pela síndrome ascítica foi significativamente maior (p<0.05) nas aves machos recebendo 3 fases alimentares, em um programa alimentar mais energético. Baseando-se nas condições sob as quais foi realizado o experimento, pode-se concluir que programas alimentares mais energéticos predispõem à ocorrência de mortalidade pela síndrome ascítica em aves para corte, especialmente as do sexo masculino.

Nutritional homeostatic capacity of a three-breed cross in poultry and associated effects of genotypes at the pea comb and endogenous viral element 1 loci

The effect of varying combinations of dietary CP, at 16, 18, and 20%, with ME, at 2,900 and 3,100 kcal ME/kg, on BW and feed conversion (FC) at 2 to 6 wk of age for a three-breed cross was evaluated. Additionally, effect of genotypes at the pea comb (P) and endogenous viral element 1 (ev1) loci on dietary treatments were evaluated. Average weekly feed intake per bird varied from 25.6 to 32.6 g for birds on 16% CP, 3,100 kcal ME/kg and 20% CP, 2,900 kcal ME/kg diets, respectively. Weekly BW and FC were highest for birds on a combination of 20% CP and 3,100 kcal ME/kg diet. On 18% CP and 3,100 kcal/ME diet, males with pea comb had significantly higher BW than those with a single comb. At the ev1 locus, differences among genotypes were significant only for BW of females on a diet consisting of 20% CP and 2,900 kcal ME/kg. Pooled data from the dietary treatments revealed that males with pea comb had significantly higher BW than males with single comb at 3 to 6 wk of age. Birds heterozygous at the ev1 locus had higher BW than those homozygous at this locus. Results of the current studies provide information necessary to develop the optimal protein and energy combination for BW and FC for a three-breed cross involving Araucona, White Leghorn, and Rhode Island Red. These studies also provide additional evidence of the possible effects of the P locus and a gene linked to it, ev1, on production traits in chickens.

Effects of protein and amino acid level fed zero to forty-two days on response of broilers to protein and amino acid levels fed forty-two to forty-nine days of age

Three studies were conducted to evaluate the effect of protein and amino acid (AA) levels fed 0 to 42 days posthatch on response of broiler chickens to levels of protein and AA fed during the finisher period. Birds were grown to 42 days on diets formulated to contain a minimum of 105 or 120% of recommended AA levels, and then randomly assigned to diets formulated to contain a minimum of 70, 80, 90, 100, 110, or 120% of recommended AA levels for 42 to 49 days. No minimum protein level was imposed on the diets. Body weight, feed intake, feed utilization, dressing percentage, abdominal fat content, and parts yield were determined. The protein and AA level fed 0 to 42 days had significant effects on 42- and 49-day body weight and 42- to 49-day feed intake of male but not female broilers. However, there was no interaction of protein and AA levels fed 0 to 42 days on response to protein and AA levels fed 42 to 49 days for these criteria. Weight gain, feed intake, and feed utilization of both males and females 42 to 49 days were significantly influenced by protein and AA levels fed during this time; protein and AA requirements of females during this time appeared to be equal to, or greater than, those of the male broiler. Although there were significant interactions of protein and AA levels 0 to 42 and 42 to 49 days on various carcass parameters for both male and female broilers, these followed no consistent pattern. Protein and amino acid levels fed 0 to 42 days had a significant influence on both quantity and percentage of abdominal fat in both male and female broilers processed at 49 days but not on any other carcass parameters. The protein and AA levels fed 42 to 49 days had a significant effect on both quantity and percentage of abdominal fat in male but not female broilers. The protein and AA levels fed 42 to 49 days significantly influenced quantity but not percentage of breast meat in male but not female broilers. The results of the current study indicate that there was minimal carryover effect of protein and AA levels fed 0 to 42 days on response to AA levels fed 42 to 49 days.

Effects of dietary amino acid level and duration of finisher period on performance and carcass content of broilers forty-nine days of age

Two studies were conducted to evaluate feeding reduced levels of amino acids (AA) to broilers during the finisher period. Birds grown to 42 days on nutritionally complete diets were fed diets formulated to contain a minimum of 70, 80, 90, 100, or 110% of recommended AA levels for periods of 3, 5, or 7 days prior to slaughter at 49 days of age. Body weight, feed intake, feed utilization, dressing percentage, and abdominal fat content were determined. For finisher periods of 3 to 5 days, a reduction in recommended dietary AA levels may be utilized without impairment of body weight gains of broilers. Extending the finisher period to 7 days resulted in significant (P less than .05) reduction of body weight gains on diets with AA levels less than 90% of recommended levels. Feed utilization was more sensitive to reduction in AA levels and may be affected adversely even by a 5-day withdrawal period. Dressing percentage was reduced in some instances, and abdominal fat generally increased when reduced AA levels were fed. The economics of feeding reduced AA levels must be considered in evaluating the results of the present studies.

Effect of dietary protein level and length of feeding on performance and abdominal fat content of broiler chickens

Dietary CP levels influence carcass fat content of chickens but the length of time necessary to feed higher levels in order to increase carcass fat is not known. Studies were conducted to evaluate the effects of length of feeding of different levels of dietary CP on broiler performance and abdominal fat deposition. All diets were calculated to be isocaloric at 3,200 kcal ME/kg. Broilers fed 23% CP for 0 to 21 days, 20% CP for 21 to 42 days, and 18% CP for 42 to 49 or 42 to 56 days served as the control group in each of two trials. In the first trial, broilers were fed constant levels of CP from day-old to market age with CP levels ranging from 15 to 27% (amino acids adjusted in proportion to CP level). Other broilers were fed 23% CP for 0 to 21 days and then fed either 15, 17, 19, or 21% CP to market age. In the second trial, broilers were fed constant levels of CP (18, 20, or 23%) from day-old to market age. Feeding CP levels lower than those fed the control group had a more pronounced effect on males than on females, with the primary effects being reduced body weight, poorer feed utilization, and increased carcass fat content. Feeding CP levels higher than those fed the control group generally did not increase final body weight but generally improved feed utilization and decreased carcass fat content. The economics of improved feed utilization and reduced carcass fat must be considered in determining dietary CP levels to use at different ages for growing broilers.

Effects of dietary amino acid levels on performance and carcass composition of broilers 42 to 49 days of age

Broilers were grown to 42 days on nutritionally complete diets. From 42 to 49 days in two trials, broilers were fed diets formulated to contain 70, 80, 90, 100, 110, or 120% of recommended amino acid (AA) values. In four additional trials, the same AA levels were fed; in addition, Met and Lys were added to diets formulated to contain 70, 80, and 90% to equal levels of the 110% AA diet. Body weight gain (BWG), feed consumption (FC), feed conversion (FCR), dressing percentage (DP), and abdominal fat (AF) were measured. From 42 to 49 days, dietary AA levels had little effect on BWG, DP, or AF of female broilers. When male broilers were fed diets containing less than 100% of the recommended AA levels, BWG was reduced and AF increased. Broiler FC increased and FCR decreased as the AA level of the diet decreased. The addition of Met and Lys to the 90% AA diet improved performance; however, the addition of Met and Lys to the 70% AA diet had no beneficial effect. Amino acid levels may be reduced in broilers diets fed from 42 to 49 days; however, male broilers are more sensitive than females to reductions in AA levels during this period.