Abstract
The objective of this research was to update current results about the nutrient composition of broiler chickens during the growth period up to market age. Two growth experiments were conducted for assessing the nutrient content of feathers and feather-free body of meat-type chickens (Ross 308). Both male and female birds were reared under uniform management conditions (floor pens; 15 pens per gender; 5 birds per pen). Experimental diets both for the starter (day 1 to 22) and the grower period (day 22 to 36) were based on corn, wheat, soybean meal, soybean protein concentrate and well balanced with feed amino acids. The feed protein quality was adapted to the ideal amino acid ratio and equated within both of the feeding periods by adjusting a constant mixture of the feed proteins. Each 15 birds per gender (3 pens of 5 birds) were selected and subsequently fasted for 24 h before quantitative de-feathering both at start of the experiment and further on weekly up to the end of the 5th week. Nutrient content was determined in representative samples of the feather and feather-free body fraction. In the feather dry matter (DM) very high crude protein (CP) concentrations (>96%) with low age-dependent and insignificant gender-specific differences were observed. In spite, a relatively high variation of CP content in the DM of feather-free body was found. Depending on age, the body CP significantly decreased with increasing age, but male birds yielded higher (p < 0.001) CP content. The crude lipid content of the feather-free and whole empty body significantly increased with age and was higher in female as compared to male birds (p < 0.001). Depending on age and gender, the crude ash content both in feathers and feather-free body of modern fast-growing chickens was rather low and with very low variation.
Highlights
The fast breeding progress in meat-type chicken [1] [2] [3] [4] has impacts on body composition as compared to birds of earlier decades
According to literature data [2] [3] [18] [21] [22] [25] [28] [35] [36] [38] [39] we found that the crude lipid (CL) content both in the feather-free and whole empty body increased with increasing age of growing chickens (p < 0.001)
The crude protein (CP) (N × 6.25) content in the feather dry matter (DM) of fast-growing meat-type chickens is independent on gender very high (>96%) and rather constant during the growing period up to market weight
Summary
The fast breeding progress in meat-type chicken [1] [2] [3] [4] has impacts on body composition as compared to birds of earlier decades. Body composition data of actual broiler genotypes provide important information for further improvement of optimized dietary protein and amino acid supply. Modern broiler genotypes require significantly higher energy and nutrient concentrations in the diet to optimize both performance data (body weight gain, body protein deposition) and efficiency of protein utilization [6]. The database for age dependent nutrient composition of whole body and body fractions like feathers in current genotypes of meat-type chickens is scarce. The present study aimed to provide actual results about age-dependent changes in whole body composition based on analyzed feathers and feather-free bodies from male and female modern meat-type chicken, making use of a recently reported database [7]
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