Estimating fat reserves in Rasa Aragonesa ewes: A comparison of different methods

Abstract

Four pre-slaughter measurements, liveweight (LW), body condition score (BCS) and fat thickness, measured by ultrasound, in the lumbar (FTL) and sternal regions (FTS), and four post-slaughter measurements, empty liveweight (ELW), hot carcass weight (HCW) and diameter of adipocytes in subcutaneous (DSC) and omental (DOM) fat depots¸ were used to predict the weight of fat in the omental (OM), mesenteric (MES), perirenal (PR), subcutaneous (SC) and intermuscular (IM) depots of ewes. Linear and multiple regressions were fitted to data from 42 adult, non-pregnant and non-lactating Rasa Aragonesa ewes, with liveweights between 29.8 and 79.2 kg and body condition scores between 0.75 and 4.5. Using a single parameter, ELW and HCW gave the most accurate predictions of the total depot fat (R2 = 0.88 and 0.90, RSD = 1.571 and 1.484 kg, respectively). Multiple regressions predicted total weight of fat depots from the pre-slaughter variables LW, BCS and FTS with an R2 value of 0.92 (RSD=1.317 kg). This result confirms the utility of using in vivo measures as fat reserve predictors in Rasa Aragonesa ewes. Key words: Fat tissue, liveweight, body condition score, adipocytes, ultrasound, ewes