The effect of protease on productive and slaughter traits in broiler chickens

Abstract

Carcass conformation is a very important parameter in assessing the overall appearance and meatiness of broilers. This study evaluates the effect of protease supplemented to reduced protein diets on production traits, dressed carcass weight and conformation measures in fast-growing Cobb 500 and slow-growing Master Gris broilers over a fattening period of 49 days. At slaughter, the following measurements were taken: pre-slaughter body weight (BW), conventionally dressed carcass weight and abdominal fat weight. Following carcass dissection into primal cuts, absolute conformation values, including metatarsus length (ML), keel length (KL), breast depth (BD), breast angle (BA) and thigh girth (TG), were determined. For carcass conformation evaluation purposes, index values of carcass conformation measures BW/ML, BW/KL, BW/BD and BW/TG were identified. Genotype and sex had a significant effect on dressed carcass weight and all conformation measures, whereas the effect of different protein levels in protease-supplemented diets was significant only in Master Gris, for metatarsus length and the following indices: BW/ML, BW/KL and BW/TG.

Konformacija trupova pilića predstavlja vrlo važan parametar za ocenu opšteg izgleda i mesnatosti pilića. U radu je analiziran efekat enzima proteaze, uz snižen nivo sirovih proteina, na proizvodne osobine, masu obrađenog trupa i mere konformacije kod brzorastućeg-Cobb 500 i spororastućeg hibrida - Master Gris. Tov pilića trajao je 49 dana. Na liniji klanja izmerena je telesna masa pilića pre klanja, masa klasično-obrađenog trupa i masa abdominalne masti. Nakon rasecanja trupova na osnovne delove izmerene su apsolutne mere konformacije: dužina piska, dužina kobilice, dubina grudi, grudni ugao i obim bataka. Za bolju ocenu konformacije trupova izračunati su indeksi mera konformacije: telesna masa/dužina piska, telesna masa/dužina kobilice, telesna masa/dubina grudi i telesna masa/obim bataka. Značajan je bio uticaj genotipa i pola na masu obrađenih trupova i sve ispitivane mere konformacije, dok je uticaj različitih nivoa proteina, uz dodatak enzima proteaze, bio značajan samo kod hibrida Master Gris, i to za dužinu piska i indekse telesna masa/dužina piska, telesna masa/dužina kobilice i telesna masa/obim bataka.