Age and Gender Dependent Nutrient Composition of Feather and Feather-Free Body Fractions in Meat-Type Chickens

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 5 th 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.

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

“…The study was conducted with 90 male and 90 female broiler chickens and performed at the facilities of the Division Animal Nutrition Physiology, Department of Animal Sciences at Georg-August-University Goettingen as approved by the Ethic Committee of the Lower Saxony Federal Office for Consumer Protection and Food Safety (LAVES), Germany. The methodical background has been described in detail in previous publications [4] [6], yet for further understanding the following modifications and additional information applied while working with the data in this study are included.…”

“…Each sample of quantitatively collected feathers and of feather-free empty body was separately stored in plastic bags at −20˚C for further processing as previously described in detail [4] [6].…”

“…Accordingly, the number of birds continuously decreased up to the last experimental period at 5 weeks of age. Considering the already reported mean body nutrient composition of each corresponding reference groups [4], the nutrient deposition was determined by computing the difference between the crude nutrient content in the whole body of birds (feathers plus feather-free body) reared during the growth study at the end and the start of each week or growth period, respectively.The energy deposition was calculated using the factor 23.7 kJ per g accreted body protein and 39.8 kJ per g accreted body fat [14]. Additionally, the concentration of nutrients and energy in gained BW was estimated as the accreted amount in g or kJ per bird divided by the realized BWG (in kg/bird) within the individual age periods.…”

“…However in more recent years, fast selection progress has played an important role for the market meat yield by increasing the body protein deposition potential of present genotypes [3]. As already reported [4] [5], 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.…”

“…The yielded data, completed by earlier published results on the age and gender dependent partitioning of the feather and feather-free body fraction [6] and their nutrient contents [4], have laid the foundations for estimating quantitative nutrient and energy deposition data for male and female birds per life week and growth period.…”