Incubation temperature manipulation during fetal development reduces adiposity of broiler hatchlings.

Broilers are known as an efficient source of lean meat. Genetic selection resulted in broiler strains with large body size and fast growth, but a concomitant increase in fat deposition also occurred. Other than reducing nutrient intake, there is a lack of alternative methods to control body fat composition of broilers. The present study assessed whether incubation temperature (machine temperatures: 36ºC, 37.5ºC, and 39ºC; eggshell temperatures: 37.4 ± 0.08°C, 37.8 ± 0.15ºC, and 38.8 ± 0.33°C, respectively.) from d 13 affects broiler hatchling fat deposition. We analyzed adipocyte hypertrophy and proliferation in 3 body regions; weight and chemical composition of yolk-free chicks and yolk sacs; and serum lipid profile. Increased incubation temperature reduced abdominal and cervical adipocyte size. Independently of temperature, cervical adipocytes were smaller and showed higher proliferation than adipocytes in the abdominal and thigh regions. Smaller cervical adipocytes were observed in birds from eggs incubated at 36ºC and 39ºC. With regard to weight and composition of chicks, ash content as a percentage of dry matter was the only variable affected by temperature; it was higher in chicks from eggs incubated at 36ºC than at 39ºC and showed no significant difference between chicks incubated at 39ºC and 37.5ºC. Absolute and relative weights of yolk sacs were higher from eggs incubated at 39ºC than at 36ºC, and these two treatments did not differ from the 37.5ºC control. Absolute measures of yolk sac lipids, moisture, dry matter, and crude protein content were lower in chicks from eggs incubated at 36ºC, and no significant differences were found for these variables between chicks from eggs incubated at 37.5ºC and 39ºC. Hatchlings from eggs incubated at 36°C had significantly higher cholesterol levels than chicks incubated at the other 2 temperatures, but no additional effects on blood lipids were detected. Incubation temperature manipulation during fetal development altered cervical and abdominal adipocyte size in broiler hatchlings and could become a tool in hatcheries to manipulate chick quality, although further studies are needed to evaluate its long-term effects.

Vitamin C prevents the effects of high rearing temperatures on the quality of broiler thigh meat1.

We investigated the effects of incubation temperatures and vitamin C injections into eggs (treatments: 37.5ºC, 39ºC, 39ºC+vitamin C) on resultant chick pectoralis major and sartorius muscle fiber hypertrophy, as well as their effects on the quality of breast and over-thigh meat of broilers reared under cold, control, or hot temperatures. Incubation at 39ºC increased the shear force and reduced meat redness in breast meat (P < 0.05). Vitamin C prevented these high temperature incubation effects [shear force (kgf cm(-2)): 37.5ºC = 2.34, 39ºC = 2.79, 39ºC+vitamin C = 2.44; redness: 37.5ºC = 2.64, 39ºC = 1.90, 39ºC+vitamin C = 2.30], but reduced water content (37.5ºC = 74.81%, 39ºC = 74.53%, 39ºC+vitamin C = 69.39%) (P < 0.05). Cold rearing temperatures increased breast meat redness (a*: cold = 2.78, control = 2.12, hot = 1.98), while hot rearing temperatures reduced the muscle fiber area (cold = 5.413 µm(2), control = 5.612 µm(2), hot = 4.448 µm(2)) (P < 0.05) without altering meat quality (P > 0.05). Hot rearing temperatures increased the cooking loss (cold = 30.10%, control = 33.66%, hot = 37.01%), shear force (cold = 3.05 kgf cm(-2), control = 3.43 kgf cm(-2), hot = 4.29 kgf cm(-2)) and redness (a*: cold = 4.63, control = 3.55, hot = 3.20) in the over-thigh meat of broilers from eggs incubated at 37.5ºC, increasing the area of muscle fibers, while cold rearing temperatures diminished cooking loss and shear force, reducing the muscle fiber area (P < 0.05). Incubation at 39ºC and 39ºC+vitamin C prevented the effects of hot and cold rearing temperatures, by diminishing and increasing the muscle fiber area, respectively.

Incubation temperature alters thermal preference and response to heat stress of broiler chickens along the rearing phase.

The current study aimed to investigate whether embryonic temperature manipulation may alter thermal preference throughout the rearing phase of broiler chickens and how this manipulation may affect response to thermal challenge, metabolism, growth rate and feed intake rate. Eggs were exposed to a constant incubation temperature [machine temperatures: 36°C (Low), 37.5°C (Control), and 39°C (High); eggshell temperature of 37.4 ± 0.08°C, 37.8 ± 0.15°C, and 38.8 ± 0.33°C, respectively] from d 13 till hatching. Low treatment chickens showed lower plasma T3 and GH levels at d 1 of age and lower T3 level at d 42 of age compared to the Control treatment. Preferred ambient, rectal temperature, T4 level, growth rate, food intake rate, and response to thermal challenge were not altered in these chickens. On the other hand, High-treatment chickens exhibited high preferred ambient temperature and rectal temperature during the first 2 wk post-hatch, lower plasma T3 level at d 21 and 42 and a delayed increase in respiratory movement in response to thermal challenge compared to the Control treatment. However, chickens subjected to the Control and High treatments did not differ in T4 and GH level and performance. We conclude that exposure to high temperature during late embryonic development has long-lasting effects on the thermoregulatory system of broiler chickens by affecting the heat tolerance of these chickens. Moreover, the preferred ambient temperature of the chickens from heat-treated eggs correspond to those recommended for the strain under study, whereas for the cold-treated and control-chickens it was 1°C below, indicating that incubation temperature might have consequences on the ambient temperature chickens require during the rearing phase.

Desempenho e rendimento de carcaça de frangos de corte alimentados com pectina na ração / Performance and carcass yield of broiler chickens fed with pectin in the ration

Avaliou-se o efeito da ingestão contínua de pectina em 720 frangos de corte sobre o desempenho e rendimento de carcaça e o consumo de água. O delineamento foi inteiramente ao acaso, em esquema de parcela subdividida, com níveis de pectina 0, 1, 3 e 5%, e idade primeira, segunda, terceira, quarta, quinta e sexta semanas, com seis repetições por tratamento. A viabilidade criatória não foi influenciada pela pectina na ração. O peso vivo, o consumo de ração e o ganho de peso diminuíram, e a conversão alimentar aumentou com a ingestão de pectina aos 35 e 42 dias. Não houve efeito da pectina sobre o consumo de ração (CR) e o consumo de água (CAg) na terceira semana. Na sexta semana, o CAg e a relação CAg:CR aumentaram com a ingestão de pectina. Aos 35e 42 dias, todos os parâmetros avaliados para rendimento de carcaça e corte diminuíram com o aumento da ingestão da fibra, sendo que apenas o rendimento de coxa+sobrecoxa não sofreu influência aos 42 dias. Os dados mostram que a ingestão contínua de até 1% de pectina na ração mantém o desempenho máximo das aves e que o consumo acima desse nível prejudica os parâmetros zootécnicos e aumenta o consumo de água na fase de maior crescimento.

The effect of the continuous intake of pectin was evaluated for 720 broilers regarding performance, carcass yield and water consumption. The design was completely randomized in a split plot design, with pectin levels of 0, 1, 3 and 5% and age 1st, 2nd, 3rd, 4th, 5th and 6th week, with six replicates. The viability was not influenced by dietary pectin. Body weight, feed intake and weight gain decreased and feed intake increased with pectin at 35 and 42 days. No effect of pectin on feed intake (FI) and water consumption (W) in the third week. On the sixth week regarding W and FI: W increased with the intake of pectin. At 35 and 42 days all parameters for carcass and cut decreased with increasing intake of fiber, and only the thigh + drumstick yield was not affected at 42 days. The data show that the continuous intake of up to 1% pectin in the diet maintains the best performance in birds and consumption above that level affects the performance parameters and increases the consumption of water in the higher growth phase.