Autores
Heloisa de Almeida Fidelis, Renata Helena Branco, Maria Eugênia Zerlotti Mercadante, Enilson Geraldo Ribeiro, Joslaine Noely dos Santos Gonçalves Cyrillo, Sarah Figueiredo Martins Bonilha
Carcass traits of nellore bulls classified for residual feed intake
Resumo
This
study was carried out to identify associations among carcass traits and
residual feed intake (RFI) in young Nellore
males feedlot finished. Data was obtained in four experiments, after the
animals had been evaluated in individual pens and classified in low RFI(<mean
- 0.5 standard deviation), medium RFI (± 0.5 standard deviation from mean) and
high RFI (> mean + 0.5 standard deviation). One hundred-sixteen non
castrated males from low and high RFI classes, with 369 kg of initial body weight
and 439 days of initial age, were used for finishing phase. Animals were distributed
in individual pens for 100 days and weighed at the beginning and end of
experimental period after 16 hours solids fasting. Animals were slaughtered with
a minimum
of 4 mm
for subcutaneous fat thickness over Longissimus
muscle between the 12th and 13th ribs. Slaughter was carried out in
experimental slaughter houses following the normal procedures of Federal
inspection. After slaughter, carcasses were weighed (hot carcass weight) and
transferred to chilling room where they were kept at 2°C for 24h. Dressing
percentage was calculated as the ratio between hot carcass weight and slaughter
body weight. After chilling, carcasses right halves were divided into carcass primary
cuts: forequarter, hindquarter and spare ribs, which were also weighed. Data
were analyzed using the SAS MIXED procedure (SAS Inst. Inc., Cary, NC), including
RFI class as fixed effect and year and genetic group as random effects with
significance level of 5%. As expected, low and high RFI animals had RFI value significantly
different (Table 1). For the other studied traits, slaughter body weight, hot
carcass weight, dressing percentage and carcass primary cuts weight, no
significant differences were detected between RFI classes. For a similar slaughter
body weight and carcass weight, low RFI animals required lesser amount of food
than high RFI animals. In the literature, variations around 10% in dry matter
intake are usually found when in comparison to animals from different RFI classes.
RFI can be considered as trait for selecting Nellore animals, due to the fact the more
efficient ones (low RFI) used less food to produce similar carcasses.
Therefore, identifying more efficient animals causes severe impact on
production system performance and profitability.
Características de carcaça de bovinos nelore classificados por consumo alimentar residual
Abstract
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