Abdominal Fat Yield Research Articles

Digestible valine requirements in high protein diets for broilers from twenty-one to forty-two days of age

The present study was conducted to estimate dietary valine (val) levels to optimize growth performance and processing yields of an early growth broiler strain fed a high protein diet. A total of 1575 Cobb×Cobb 500 male broilers were fed a common starter diet to 21d of age. From 21 to 42 days broilers were given all vegetable maize–soybean meal experimental diets. A basal diet formulated with 6.4g digestible (dig) Val/kg and a summit diet with 9.7gdigVal/kg, both having all other essential amino acids (AA) above recommendations, were mixed to produce seven diets with progressive increments of 6gdigVal/kg. Each treatment had 9 replicate pens of 25 birds. Requirements of dig val were estimated using quadratic regressions and the broken line model. Estimations of requirements were of 8.5 and 8.2gdigVal/kg for body weight gain, 8.4 and 8.1gdigVal/kg for feed conversion ratio and 8.5 and 7.3gdigVal/kg for abdominal fat yield using quadratic and broken-line models, respectively. No differences among treatments were detected for carcass and commercial cuts. The requirements determined in this study were higher than usually recommended for broiler males from 3 to 6 weeks. However, the calculated ratios of dig val to dig lysine of 77% and 76% for body weight gain and feed conversion ratio are similar to recently published data.

Supplementing L-valine and L-isoleucine in low-protein corn and soybean meal all-vegetable diets for broilers

SUMMARY Corn and soybean meal broiler feeds frequently have Val and Ile as the next-limiting amino acids after Met, Lys, and Thr. Supplementation of l -Val and l -Ile is soon likely to be feasible. One study was conducted to evaluate broilers fed diets having increased Val- and Ile-to-Lys ratios from 14 to 35 d. A total of 1,775 Cobb × Cobb 500 male broilers were fed a corn and soybean meal all-vegetable diet containing 1.10% digestible Lys. This diet was formulated without CP restriction by using synthetic Lys, Met, and Thr to attain the lowest Ile-to-Lys ratio while maintaining sulfur amino acids and Thr ratios to Lys of 75 and 65%; the diet was deficient in Val (ratio to Lys of 70%), with a minimum requirement ratio of Ile to Lys (65%). Graded increases in Val and Ile, respectively, were prepared using supplementation of l -Val and l -Ile at the expense of kaolin in 5 and 3% intervals to produce the following treatment ratios: 75 and 65%, 80 and 65%, 70 and 68%, 70 and 71%, 75 and 68%, and 80 and 71%. There were 9 replicate pens per treatment, with 25 male broilers per pen. Performance differences were detected mainly from 14 to 21 d of age; feed intake was reduced for broilers fed the basal diet, whereas BW gain and FCR were improved when Val- and Ile-to-Lys ratios were increased. From 14 to 35 d, the lowest levels of Val and Ile led to reduced BW gain but did not influence FCR. No differences were found among treatments for mortality and carcass yield, commercial cut yields, and abdominal fat yields. Diets formulated without minimum CP restrictions with Val- and Ile-to-Lys ratios of 70 and 65 resulted in impaired live performance. This was overcome when l -Val or l -Ile was supplemented to simultaneous ratios of Val and Ile to Lys of 75 and 65% or 70 and 68%.

Avaliação do desempenho e do rendimento de carcaça de quatro linhagens de frangos de corte em dois sistemas de criação

O objetivo neste trabalho foi avaliar o desempenho e o rendimento de carcaça e das partes de quatro linhagens de frangos de corte criados em sistemas de confinamento e semiconfinamento. Foram utilizados 1.440 pintos distribuídos em delineamento inteiramente casualisado com esquema fatorial 4 õ 2, composto de quatro linhagens (Ross 308, Máster Griss, Label Rouge e Vermelhão Pesado) e dois sistemas de criação (em confinamento e semiconfinamento), cada um com quatro repetições de 45 aves. Aos 84 dias de idade, foram abatidas quatro aves por repetição, totalizando 128 aves, para avaliação do rendimento de carcaça e das partes. O acesso ao piquete (semiconfinamento) não influenciou o desempenho nem o rendimento de carcaça das linhagens, exceto o rendimento de gordura abdominal, que foi mais baixo nas aves semiconfinadas. Considerando apenas aves das linhagens tipo colonial, a Máster Griss e Vermelhão Pesado tiveram melhores resultados de peso e a Label Rouge, melhor conversão alimentar. Os frangos tipo colonial Máster Griss, Label Rouge e Vermelhão Pesado, em comparação aos da linhagem comercial Ross, apresentaram maior rendimento de partes, exceto de peito e carne de peito, que foram maiores na linhagem Ross. A escolha da linhagem deve ser feita de acordo com o interesse de mercado, pois há diferenças no desempenho e no rendimento de carcaça e das partes.

Dietary limitation of isoleucine and valine in diets based on maize, soybean meal, and meat and bone meal for broiler chickens

1. The dietary limitation of isoleucine (Ile) and valine (Val) was evaluated in broilers. Common diets were given to all broilers from 0 to 28 d of age. Experimental diets were provided from 28 to 42 d of age. 2. The experimental test diet was based primarily on maize, soybean meal, and meat and bone meal, and formulated to satisfy all nutrient recommendations with the exception of Ile and Val. 3. Diets were supplemented with L-Ile and L-Val at either 0·5 or 1·0 g kg−1 of diet, alone or in combination. A diet composed only of commercially available amino acids and formulated to satisfy all nutrient requirements served as a positive control. 4. Body weight gain was depressed by the test diet, but recovered to a weight similar to birds fed on the positive control when Val was added to the test diet either alone or in combination with Ile. Feed efficiency improved when Val and Ile were simultaneously supplemented. 5. Abdominal fat yield was reduced with the combined supplementation of Val and Ile. Breast meat yield appeared to be more sensitive to Ile supplementation than to Val. 6. The results suggest that live performance may be more sensitive to Val, while breast meat yield was maximised with Ile supplementation. However, their combination is required for optimised growth and meat yield.

Níveis de metionina + cistina para características de desempenho e de carcaça em codornas de corte EV2

Estudou-se a exigência de metionina + cistina para codornas de corte em crescimento. O delineamento experimental foi inteiramente ao acaso, com cinco repetições de 13 codornas por unidade experimental. Os tratamentos consistiram de seis níveis de metionina + cistina - 0,73; 0,79; 0,85; 0,91; 0,97 e 1,03%. Foram registrados peso corporal (g), ganho de peso (g), consumo de ração (g) e conversão alimentar (g/g) em cada fase de crescimento (7º ao 21º dia) e total (7º ao 42º dia de idade). No 42º dia, quatro codornas de cada unidade experimental (dois machos e duas fêmeas), após jejum de sólidos de oito horas, foram amostradas, pesadas e abatidas para avaliação dos pesos e rendimentos de carcaças em relação ao peso vivo e rendimentos dos cortes (peito e coxas) e das vísceras comestíveis (fígado, moela e coração) e gordura abdominal em relação ao peso da carcaça eviscerada (sem pés e sem cabeça). Os níveis de metionina + cistina da dieta influíram de forma quadrática no peso ao 21º dia e no ganho de peso do 7º ao 21º dia de idade das codornas, com máximo desempenho em 0,95% de metionina + cistina. A conversão alimentar apresentou comportamento linear decrescente significativo. Houve efeito linear dos níveis dos aminoácidos metionina + cistina sobre o peso ao 42º dia, ganho de peso e consumo de alimento do 7º ao 42º dia de idade. Não houve efeito dos níveis de metionina + cistina da dieta sobre o peso vivo, peso e rendimento de carcaça, peito, coxa, gordura abdominal, fígado, moela e coração. Maiores peso corporal, carcaça eviscerada, coxa, peito, gordura abdominal, moela, peso e rendimento de fígado foram observados nas fêmeas, enquanto os machos apresentaram maior rendimento de carcaça eviscerada. Maior ganho de peso foi observado em codornas de corte EV2 em crescimento alimentadas com dietas que continham 0,95% de metionina + cistina na fase inicial (7º ao 21º dia) e 1,03% na fase total (7º ao 42º dia de idade), o que corresponde às relações de metionina + cistina: lisina de 0,73 e 0,79%, e ao consumo de metionina + cistina diário de 0,134g e 0,234g/codorna, respectivamente.

Performance and Carcass Quality of Broiler Chickens Fed a Corn-soybean Meal Diet Containing Graded Barley Levels without or with Enzyme

Three experiments were conducted to evaluate broiler chicken performance, ready-to-cook carcass value, and the size of cut-up parts of the left carcass section in response to feeding a corn-soybean meal diet containing graded levels of Litani (L2), Pamir 35 (P2), or Rihan 03 (R6) barley without or with 0.1% enzyme. In the first experiment, a diet containing 25% L2 or R6 without or with enzyme was fed during the finisher period. Enzyme supplementation of the barley containing diets improved (P<0.01) broiler weight gain and feed conversion values. Enzyme containing diets supplemented with 0, 15, 30, and 45% L2, P2, and R6 were fed from hatch to 42d of age in the second experiment. There was a decrease (P<0.06) in cumulative performance with a concomitant increase (P<0.01) in abdominal fat pad yield when the level of barley was increased to 45%. In the third experiment, diets containing 15, 20, 25, 30, and 35% R6 without or with enzyme were fed from hatch till market age. Enzyme addition improved feed conversion and increased abdominal fat pad yield whereas breast muscle and thigh yields were decreased when barley level exceeded 25% (P<0.01). In conclusion, enzyme supplementation to barley diets improved efficiency of feed utilization but increased abdominal fat yield with no significant effect on breast muscle, thigh, and drum yields. The current findings indicate that levels up to 25% of R6 barley could be incorporated in diets up to market age without affecting broiler production parameters.

Effect of a free-range raising system on growth performance, carcass yield, and meat quality of slow-growing chicken

Experiments were conducted to evaluate the effect of free-range raising systems on growth performance, carcass yield, and meat quality of slow-growing chickens. Slow-growing female chickens, Gushi chickens, were selected as the experimental birds. Two hundred 1-d-old female chicks were raised in a pen for 35 d. On d 36, ninety healthy birds, with similar BW (353.7 ± 32.1g), were selected and randomly assigned to 2 treatments (indoor treatment and free-range treatment, P > 0.05). Each treatment was represented by 3 groups containing 15 birds (45 birds per treatment). During the indoor treatment, the chickens were raised in floor pens in a conventional poultry research house (7 birds/m2). In the free-range treatment, the chickens were housed in a similar indoor house (7 birds/m2); in addition, they also had a free-range grass paddock (1 bird/m2). All birds were provided with the same starter and finisher diets and were raised for 112 d. Results showed that the BW and weight gain of the chickens in the free-range treatment were much lower than that of the chickens in the indoor floor treatments (P < 0.05). There was no effect of the free-range raising system on eviscerated carcass, breast, thigh, and wing yield (P > 0.05). However, the abdominal fat yield and tibia strength (P < 0.05) significantly declined. The nutrient composition (water, protein, and fat), water-holding capacity, shear force, and pH of the muscle were largely unaffected (P > 0.05) by the free-range raising system. The data indicated that the free-range raising system could significantly reduce growth performance, abdominal fat, and tibia strength, but with no effect on carcass traits and meat quality in slow-growing chickens.

Effect of poultry viscera meal inclusion in broiler diets in different rearing periods on performance, carcass and parts yields

The objective of the present study was to evaluate the effect of the dietary inclusion of poultry viscera meal (VM) on broiler performance and carcass, parts, and abdominal fat yields in broilers by replacing a diet containing VM with a strictly vegetable diet and vice-versa. A number of 720 one-day-old broiler chicks were randomly distributed in 6 groups: G1-basal diet (BD) - corn and soybean based meal, with no VM from 1 to 42 days of age, G2- 8% VM diet from 1 to 42 days, G3- BD from 1 to 21 and 8% VM diet from 22 to 42 days, G4- BD from 1 to 35 and 8% VM diet from 36 to 42 days, G5- 8% VM diet from 1 to 21 days and BD from 22 to 42 days, G6- 8% VM diet from 1 to 35 and BD from 36 to 42 days. Average body weight, weight gain, feed intake, feed conversion ratio (FCR), production efficiency index, and mortality were determined from 1 to 42 days. There was no effect of treatments on performance or mortality, except for FCR, which was significantly better in the group fed VM from 1 to 35 days and withdrawn at the end of rearing (36-42 days). Also, there were no differences in carcass, parts, and abdominal fat yields, showing that VM in broiler diets does not influence yield parameters.

Dietary glutamine supplementation improves growth performance, meat quality and colour stability of broilers under heat stress

1. The present study was conducted to investigate the effects of dietary glutamine (Gln) supplementation on growth performance, carcase characteristics and meat quality in broilers exposed to high ambient temperature. 2. A total of 240 35-d-old male Arbor Acres broilers were randomly assigned to 4 treatment groups (three replicates of 20 birds per cage). The broilers were kept in a temperature-controlled room at either 23°C (no-stress groups, NS) or 28°C (heat stress groups, HS). The broilers were fed either on a basal diet (control, NS) or on the basal diet supplemented with 0, 0·5 or 1·0% Gln (HS). 3. Compared with the NS, the HS (0% Gln) group gained less weight and consumed less feed, had lower final body weight, gain-to-feed ratio, and abdominal fat yield. Breast meat in HS (0% Gln) had lower pH, water-holding capacity (WHC), a* value, ether extract (EE) content and crude protein (CP) content, and had higher shear force (SF) and L* value. 4. Linear increase were found in groups supplemented with Gln (0, 0·5% and 1·0%) for final body weight, weight gain, feed consumption, gain-to-feed ratio and abdominal fat yield. Supplementation with Gln improved breast meat pH, WHC, SF, L* value, a* value, EE content and CP content in broilers exposed to heat stress. No significant difference was observed in all the indices determined between the HS (1% Gln) and the NS. 5. Heat stress caused obvious breast meat discoloration in L*, a* and b* values. However, dietary supplementation with Gln gave a better colour stability. 6. The results indicated that dietary supplementation with Gln may alleviate heat stress-caused deterioration in growth performance, carcase characteristics, meat quality and meat colour stability of broilers.

Effects of metabolizable energy and lysine restrictions on growth performance, blood profiles, and expression of myostatin and leptin genes in broilers

To investigate the effects of metabolizable energy and lysine restriction on performance, and gene expression of leptin and myostatin, three hundred twenty day-old Ross broiler chicks were randomly allotted to four treatments. Birds were subjected to their respective diets comprising two levels of ME (3200; 2880 kcal kg-1) and two levels of lysine (1.10; 0.88%) during days 8 to 21. The dietary crude protein levels were reduced with the proportion to the lysine levels, while ratios of essential amino acids relative to lysine were similar for all diets. During restriction, weight gain, breast muscle and abdominal fat yield were lower in birds fed lysine-restricted diets. Relative myostatin mRNA abundance was increased in breast muscle of lysine-restricted birds, while expression of leptin mRNA in abdominal fat was downregulated by energy and lysine restriction. During realimentation, birds previously fed with energy and/or lysine-restricted diets had comparable performance as birds fed unrestricted diets. At day 42, energy and lysine restriction increased relative myostatin mRNA expression in breast muscle and birds previously fed diet restricted in both energy and lysine had the highest relative myostatin mRNA expression (energy × lysine interaction, P &lt; 0.001). The relative leptin mRNA abundance was significantly lower in birds previously fed energy-restricted diets. These results indicated that early energy and lysine restriction from day 8 to 21 exhibited growth compensation during realimentation. In addition, myostatin and leptin mRNA expression in breast muscle and abdominal fat were modulated by nutritional treatments and were closely associated with changes in breast muscle yield and abdominal fat deposition. Key words: Metabolizable energy, lysine, myostatin, leptin, broiler

Desempenho e características de carcaça de frangos de corte alimentados com dietas à base de milho e farelo de soja suplementadas com complexos enzimáticos

Um experimento foi conduzido para avaliar o efeito da suplementação de complexos enzimáticos à dieta sobre o desempenho e as características de carcaça de frangos de corte de ambos os sexos. Avaliaram-se cinco dietas: controle positivo - à base de milho e farelo de soja com farinha de carne e ossos, sem enzima; controle negativo - formulada com 3% menos de energia metabolizável; controle negativo + 0,05% do complexo A (xilanase, 600 U/g; amilase, 8.000 U/g; e protease, 800 U/g); controle negativo + 0,04% do complexo B (α-amilase, 200 kNU/g; e β-glucanase, 350 FBG/g); e controle negativo + 0,04% do complexo B + 0,01% da enzima C (xilanase, 1.000 FXU/g). Não foram observadas diferenças no desempenho das aves no período de 1 a 7 dias de idade. Na fase de 1 a 21 dias de idade, os machos consumiram mais ração e as dietas com o complexo B resultaram em maior ganho de peso. Os melhores resultados de conversão alimentar foram obtidos com o uso dos complexos enzimáticos. No período total, o consumo de ração foi menor entre as aves (machos e fêmeas) mantidas com a dieta controle positivo, enquanto o maior ganho de peso nos machos foi obtido com a dieta controle negativo contendo 0,04% do complexo B. Quanto à conversão alimentar, os machos apresentaram as melhores conversões com o uso dos complexos enzimáticos. Não houve efeito das dietas sobre os rendimentos de carcaça, peito e gordura abdominal. Quando fornecidas dietas com redução de 3% da energia metabolizável, o uso dos complexos enzimáticos é efetivo na recuperação do desempenho das aves.

Performance, abdominal fat deposition and bone characteristics of broilers fed diets containing different lipid sources

Two experiments were carried out to evaluate the performance, abdominal fat yield, and bone parameters of broiler chickens fed diets containing different lipid feedstuffs as energy source. During the starter phase (1 to 21 days) of Experiment 1, a completely randomized design with four treatments with eight replicates of 49 birds each one was applied. Broilers were fed starter diets formulated with different lipid sources: soybean oil (SO), cottonseed oil (CO), poultry offal oil (PO), and beef tallow (BT). During the finisher phase (21 to 42 days) of Experiment 1, each initial treatment was divided in two experimental groups: one fed the same fat ingredient as the previous period, and the other fed SO as energy source. Thus, during this period, a completely randomized design with seven treatments, four replicates, and 43 broilers per experimental unit was tested. During the starter phase (1 to 21 days) of Experiment 2, all broilers were fed with the same soybean oil-supplemented diet. The experimental groups were divided during the finisher phase (21 to 42 d) in a completely randomized design with five treatments groups with six replicates of 30 birds each. During this period, treatments consisted of diets formulated with SO, rapeseed oil (RO), sunflower oils (SFO), PO, or BT as lipid sources. No effects (P>0.05) of the treatments on any of the studied parameters were observed in either experiment. Results suggest that there is no influence of animal or vegetable dietary lipid sources on performance, abdominal fat deposition, or tibia density and strength in broilers.

Avaliação do coeficiente de variação como medida da precisão em experimentos com frangos de corte

Estabeleceram-se faixas de coeficientes de variação (CV) que orientem a avaliação de determinadas variáveis em pesquisas futuras. Foram coletados dados de CV de vários trabalhos publicados no Brasil, com ênfase em frangos de corte, abordando: ganho de peso, consumo de ração, conversão alimentar, mortalidade, viabilidade, peso vivo e rendimentos de carcaça, de peito, de pernas, de gordura abdominal, de asas e de dorso. Utilizou-se uma tabela que relaciona mediana (Md) e pseudo-sigma (PS) para estabelecer os intervalos de CV de cada variável. O rendimento de gordura abdominal apresentou faixa de variação com maiores coeficientes de variação; para as demais variáveis, as faixas de classificação dos coeficientes de variação mostraram-se relativamente baixas.

Effects of Betaine Supplementation to Methionine Deficient Diet on Growth Performance and Carcass Characteristics of Broilers

Problem Statement: The efficacy of Methionine (Met) sparing effect of Betaine (BET) has been shown to be associated with dietary compositions, animal physiological stage and living conditions. This study was to determine the extent to which dietary Met could be replaced by BET in broiler chickens under the feeding conditions specific to Chinese poultry industry.Approach: A total of 900 day-old Arbor Acres broiler chicks were fed three corn-soybean meal-based starter rations (d 1-21) and grower rations (d 22-42) for a total of 42 days. Met levels in the diets were: Diet 1, Met content at the recommended level (Control); diet 2, Met level at 85% of the Control supplemented with BET at the level of 400 (starter) or 300 (grower) mg kg-1 DM; Diet 3, Met level at 75% of the Control supplemented with BET at the level of 600 (starter) or 500 (grower) mg khg-1 DM. The broilers were raised in a temperature controlled house with 3 pens (replicates) per dietary treatment. Results: In general, treatment had no effect on body weight, feed intake or feed efficiency. Concentrations of growth hormone and insulin-like growth factor-1 in the serum of broilers fed Diet 3 were higher (p<0.05) than that of broilers of other treatments. Supplementation of BET at the level of replacing 25% of total Met increased (p<0.05) breast meat yield and protein content of breast meat and liver, but decreased (p<0.05) abdominal fat yield and ether extract content of liver. Conclusions/Recommendations: Supplementation of BET to replace up to 25% of total dietary Met did not affect the growth performance but improved the carcass quality of the broilers. BET could be used to spare 25% of the total Met in broiler diet that was formulated based on the Feeding Standard of China.

Effect of carbohydrate supplementation provided through drinking water during feed withdrawal on meat and liver colours in broilers

BACKGROUND:The effect of saccarose supplementation provided through drinking water during feed withdrawal on meat and liver colour was investigated in a total of 50 broilers (five floor pens with 10 broilers) at 43 days. Treatments consisted of: (1) full-fed control broilers fed the standard broiler diet and water for the full 10 h (control); (2) fasted broilers receiving only water (FW); (3) 1 g (0.01SW); (4) 2 g (0.02SW); and (5) 3 g (0.03SW) saccarose L−1 supplemented water for the 10 h. The CIE colour values representing lightness (L*), redness (a*), and yellowness (b*) were measured on raw livers, breast and thigh meats. RESULTS:Full-fed broilers had lower dressing percentage, higher abdominal fat and liver yield and lighter thigh meat coloration than the FW birds (P < 0.05). The 0.02SW and 0.03SW resulted in live shrinks that were lower (P < 0.05) than those found in FW broilers. The 0.02SW and 0.03SW resulted in liver colours that were lighter than those found in FW and 0.01SW birds but darker than from control birds (P < 0.05). CONCLUSION:It was concluded that saccarose supplementation during feed withdrawal appears to have a measurable impact on live shrink, and lightness of liver and thigh meat colour in broilers. Copyright © 2007 Society of Chemical Industry

Composto exaurido do cogumelo Agaricus blazei na dieta de frangos de corte

Avaliou-se o efeito da substituição de um antibiótico por diferentes níveis do composto exaurido do cogumelo (CEC) Agaricus blazei sobre o desempenho de frangos de corte de 1 a 42 dias de idade. Foram avaliadas sete dietas, seis com adição de CEC (0,0; 0,2; 0,4; 0,6; 0,8 e 1,0%) e uma com antibiótico (avilamicina 10 ppm). Foram utilizados 588 pintos de 1 dia de idade, distribuídos em um delineamento inteiramente casualizado, com seis repetições por dieta (três por sexo) e 14 aves por unidade experimental. As aves que não receberam qualquer aditivo na dieta apresentaram os piores resultados de desempenho. Níveis de CEC superiores a 0,4% ocasionaram redução gradual no desempenho. O nível de 0,2% de CEC proporcionou o maior ganho de peso e o de 0,21%, a melhor conversão alimentar e o maior consumo de ração. À exceção do rendimento de peito e do rendimento de gordura abdominal, os aditivos não influenciaram os rendimentos de carcaça e dos cortes. O composto exaurido do cogumelo Agaricus blazei pode ser utilizado como aditivo alternativo ao antibiótico no nível de 0,2% da dieta, pois não prejudicou o desempenho produtivo e o rendimento de carcaça das aves.

Dietary Sodium and Chloride for Twenty-Nine-to Forty-Two-Day-Old Broiler Chickens at Constant Electrolyte Balance Under Subtropical Summer Conditions

The study was conducted to evaluate the response of broiler chicks to different dietary Na+ and Cl− concentrations with similar dietary electrolyte balance of 250 mEq/kg during 29 to 42 d of age in a hot environment with average minimum and maximum temperatures of 32.4 and 36.6°C, respectively, and an average RH of 69.2%. Three levels of dietary Na+ (0.20, 0.25, and 0.30%) and 3 levels of dietary Cl− (0.30, 0.40, and 0.50%) were used in 3 × 3 factorial arrangement in which BW at 28 d were used as covariate in the statistical analysis. A decreasing linear effect of dietary Na+ was observed on breast yield and lowering of abdominal fat, whereas increasing dietary Cl− linearly increased litter moisture and decreased dressing weights. No significant effects of dietary Na+, Cl−, or Na+ × Cl− were observed on feed intake, BW gain, feed:gain, rectal temperature, water:feed, or mortality. An improvement in litter condition, toe ash, blood parameters, and lowered abdominal fat yield was observed for the diet having 0.30% dietary Na+. The results of the present study suggest the dietary requirements of 0.20 to 0.25% Na+ and 0.30% Cl− during the finisher phase (29 to 42 d) of broiler chicks when the ambient temperature ranged from 32 to 40°C.

Effect of Early Feed Restriction on Metabolic Programming and Compensatory Growth in Broiler Chickens

The effect of early feed restriction on metabolic programming and compensatory growth was studied in broiler chickens. A total of 480 female 1-d-old broiler birds (Aconred) were randomly allocated to ad libitum and feed-restricted groups, each of which was replicated 6 times with 40 birds per replicate. Broilers were provided commercial diets. Feed-restricted broilers were deprived of feed for 4 h per day from 1 to 21 d of age. Effects of treatments were determined at 21 and 63 d of age. In feed-restricted birds at 21 d of age, BW, average daily gain and average daily feed intake, breast muscle (P < 0.01), carcass yield (P < 0.05), and abdominal fat (P < 0.05) were decreased. Ether extract content in breast muscle was increased (P < 0.01), whereas CP content was slightly decreased. Triiodothyronine (P < 0.01) and thyroxine (P < 0.05) were decreased in serum. Free fatty acid and very low density lipoprotein were slightly increased in serum, whereas triglyceride and glucose were decreased (P < 0.01). Activities of NADPH-generating enzymes in liver including malic dehydrogenase, isocitrate dehydrogenase, and glucose-6-phosphate remained unchanged in ad libitum birds, whereas hormone-sensitive lipase activity was increased (P < 0.01). In feed-restricted birds at 63 d of age, BW, average daily gain, average daily feed intake, carcass yield, breast muscle yield, and serum triiodothyronine and thyroxine remained as ad libitum birds, whereas abdominal fat yield was increased (P < 0.05). Ether extract content in breast muscle was decreased (P < 0.01), whereas CP content was increased (P < 0.05). Activities of NADPH-generating enzymes were significantly increased, except abdominal malic dehydrogenase and hormone-sensitive lipase activity was decreased (P < 0.01) in liver and abdominal fat. Lipoprotein lipase activity was increased (P < 0.05) in abdominal fat. In summary, feed restriction severely affected growth performance and lipid metabolism in broilers in the early period. Because there was no statistical difference among the final BW, near full compensatory growth was achieved. In addition, early feed restriction might have induced prolonged metabolic programming in chicks and led to adult obesity.

Interactions between the naked neck gene, sex, and fluctuating ambient temperature on heat tolerance, growth, body composition, meat quality, and sensory analysis of slow growing meat-type broilers

Abstract Influence of the Naked Neck gene, NA , on heat tolerance was evaluated in slow growing meat-type chickens in interaction with sex. Standard male Ross broilers were used as rapid growth controls. Fluctuating temperature was used to simulate day–night variations, i.e. 17 °C to 23 °C in normal and 27 °C to 33 °C in hot conditions. Male and female chickens were weighed twice and once a week, respectively, and Gompertz function was fitted to our data to calculate theoretical age at 1 kg (A1K) and 2 kg (A2K). Carcass, abdominal fat, breast and leg yields were measured (CY, AFY, BRY, and LY). Meat quality was evaluated 24 h post-mortem with pH and colour (L, a ⁎ , b ⁎ ) of the breast, and 72 h post-mortem with breast meat drip loss (DL). Rectal temperature and its variation were measured at the maximum and minimum ambient temperature at 1 and 2 kg (RT2 min , RT2 max , and ΔBT 2 kg ). Hematocrit (HCT, ΔHCT) were measured at the same stages. Organoleptic characteristics of breast and leg muscles were studied for females from both ambient temperatures. Significant genotype × sex × temperature interaction was observed for A2K, AFY, RT2 max , ΔBT 2 kg , and ΔHTC 2 kg . Hot condition did not affect ΔBT 2 kg and A2K in homozygous NA birds; ΔBT 2 kg was markedly increased in all other genotypes for males but not for females. Significant genotype × environment interactions were found only for A2K and CY. Sex × temperature interactions were found for all traits except for A1K, b ⁎ , pH, and ΔHCT 2 kg . In both conditions, males reached 2 kg at the same age (69 d) while females reached this weight 11 d latter in hot than in normal condition. Heat decreased CY in males (− 1.0%) and increased it in females (+ 1.4%). Meat was paler in males and darker in females in the hot condition leading to a difference in meat brightness between males and females only in the hot condition. Concerning sensory analysis, genotype × temperature interaction was significant for meat consistence, both in leg and breast muscles. Effects of the NA gene on susceptibility to heat stress were smaller in slow growing animals than in broilers. However, heat tolerance was still improved in homozygous NA slow growing birds, as shown by the limited change in diurnal variation of body temperature. Furthermore, the NA gene improved breast meat percentage. In contrast to broilers, where females should be recommended for production in hot climates, the present study would rather suggest that naked neck males from slow-growing meat-type ‘label’ chicken lines should be preferred.

Influence of Age and Sex on Footpad Quality and Yield in Broiler Chickens Reared on Low and High Density Diets

The effect of age and sex on live performance, processing yields, and footpad quality of broiler chickens was evaluated by rearing 2 commercial strain-crosses (SC) to 56 d of age on 2 diets varying in nutrient density. Each strain cross was placed in 10 replicate pens of 50 birds (25 males and 25 females per pen). Equally distributed among the replicate pens were high- and low-density starter (0 to 21 d) and grower (22 to 42 d) diets with a common finisher fed from 43 to 56 d to all birds. Body weights, adjusted feed conversion, and mortality were determined at 21, 42, and 56 d of age. Processing yields, foot weights, and yields, and the incidence and severity of footpad dermatitis were evaluated on d 35, 42, 49, and 56.No differences (P > 0.05) were seen in mortality between the SC and diet density treatments throughout the course of the study. Strain-cross had a significant effect on body weights at d 21 and feed conversion at d 42, but no differences remained at d 56. Significant SC effects were present for carcass without giblets at d 35, 42, and 56. Diet density effects were limited to carcass without giblets at d 35 and abdominal fat content at d 56. As expected, females had higher abdominal fat yields than males at all ages examined.Foot weight and yields were significantly affected (P < 0.05) by SC and sex at d 42, 49, and 56. As expected, foot weights increased with age. The proportion of birds with footpad dermatitis tended to increase until 49 d of age after which they started to decline. Male broilers had significantly higher incidence of footpad dermatitis than female broilers at d 49 and 56. Footpad dermatitis response to diet density and pigmentation of the feet was dependent on SC.