Age and Gender Dependent Deposition of Crude Nutrients and Energy in Fast Growing Meat-Type Chickens

Studies have shown that the body composition of recently produced broiler chickens has changed as compared to birds of earlier decades. Furthermore, it has been demonstrated that the nutrient content is considerably affected by the age and gender of the birds. However, research on the nutrient deposition in the whole body and body fractions of modern fast growing meat-type broiler chickens during the entire growth period is scarce.

In this paper, two consecutive growth studies were conducted to investigate the age-dependent nutrient and energy deposition in male and female meat-type chickens (Ross 308) based on feather and feather-free body fraction data determined according to the comparative slaughter technique. The study was conducted with 90 male and 90 female broiler chickens. Freshly hatched meat-type broiler chicks (ROSS 308) were obtained from a commercial hatchery and allocated initially in a large floor pen on wood shavings. 

Both the starter (day 1 to 22) and grower diets (day 22 to 36) were based on corn, wheat, soybean meal, soybean protein concentrate and crystalline feed amino acids. Diets were formulated to ensure an equal feed protein quality close to the ideal amino acid ratio by adjusting a constant mixture of the feed proteins. Individual body weight (BW) and feed intake per pen were recorded weekly. At the start (day 1) as well as on a weekly basis until the end of the 5th week, 15 birds per gender (each 3 pens of 5 birds) were selected and euthanized following 24 h feed deprivation. Subsequently, the feathers were manually removed and quantified. Crude nutrient analyzed in representative samples of both feather and feather-free body fractions. 

The results showed that the nutrient and energy deposition in the bodies of both genders were significantly increased with increasing age (p < 0.001). Male birds deposited significantly higher body protein (p < 0.001) and female birds significantly more fat and energy in the whole body (p < 0.001) during the entire growth period. In contrast, no differences were found in protein contents of the BW gain between genders dependent on age (p > 0.05). However, the protein partitioning in the gain of both analyzed body fractions provided oppositional results. Accordingly, male birds yielded relatively more protein in the feather-free body fraction (p < 0.001) and females relatively more feather protein (p < 0.001) as related to the whole body protein gain.

In conclusion, the crude protein (CP) composition of the BW gain (BWG) was remained insignificant between both genders, but the protein partitioning in the feather and feather-free body fraction provided oppositional results. And the feather protein percentage must be supposed as a variable parameter, especially during the rapid growth period of birds.

Article by Christian Wecke and Frank Liebert, from Georg-August-University of Goettingen, Goettingen, Germany.

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