Effect of dietary protein level and length of fattening period on dressing percentage and carcass conformation in broiler chickens

Abstract

This study analyses the effect of different protein levels in broiler feeds (supplemented with protease) and different lengths of fattening period on some parameters related to dressed carcass quality. Medium-growing Master Gris broiler chickens were used in a fattening trial lasting 63 days. At slaughter, dressing percentages and abdominal fat percentages were determined based on traditionally dressed carcass weights and abdominal fat weights of broilers at 49 and 63 days, and conformation indices were calculated based on absolute conformation measurements. Results showed that dietary treatment had an effect only on one relative conformation measurement - body weight/shank length in chickens at 49 days, as control broilers had higher values of this index compared to chickens receiving feeds containing reduced levels of crude protein and protease supplementation (0.2% or 0.3%). Length of fattening period affected almost all studied parameters, except breast angle, dressing percentage of traditionally dressed carcass and abdominal fat percentage.

U radu je analiziran uticaj različitog nivoa proteina u hrani za tov pilića (uz dodatak enzima proteaze) i dužine trajanja tova na neke parametre kvaliteta obrađenih trupova. U ogledu je korišćen medium-growing linijski hibrid Master Gris, a ogled je trajao 63 dana. Na liniji klanja, na osnovu mase klasično obrađenog trupa i mase abdominalne masti pilića uzrasta 49. i 63.dana tova utvrđen je randman klasimično obrađenog trupa i udeo abdominalne masti, a na osnovu apsolutnih mera konformacije izračunati su indeksi mera konformacije. Rezultati ogleda su pokazali da je uticaj ispitivanih obroka ispoljio efekat samo na jednu relativnu meru konformacije trupova - telesna masa/dužina piska kod pilića starosti 49.dana, jer su pilići iz kontrolne grupe imali veću vrednost ovog indeksa u odnosu na piliće koji su hranjeni smešama sa nižim nivoima sirovih proteina, uz dodatak enzima proteaze (0,2% ili 0,3%). Različita dužina trajanja tova uticala je na skoro sve ispitivane parametre, izuzev na veličinu grudnog ugla, randman klasično obrađenog trupa i udeo abdominalne masti.