Predição dos componentes teciduais da carcaça de cordeiros

Abstract

The aim of this paper was to verify the accuracy of ultrasound to measure the thickness of subcutaneous fat, the depth of Longissimus and Gluteus medius muscles and develop prediction models from ultrasound measurements to estimate the tissue composition of lamb carcasses. 36 uncastrated male Pantaneiro lambs were used as sample, distributed in a completely randomized design and then slaughtered; their weight was of 20, 25, 30 and 35 kilograms. The animals were divided into two statistical groups: light (20 to 25 kg) and heavy (30 and 35 kg). The animals were housed in individual pens and fed ad libitum until they reached the predetermined weights. On the day before the killing, ultrasound images were taken between the 12th and 13th ribs to obtain the loin depth (LMD) and subcutaneous fat thickness (SFT); from the rump (P8) the depth of gluteus images were obtained (DP8), besides fat thickness (FTP8). Pearson correlations were estimated alongside with a multiple linear regression model with the stepwise method between the measurements in vivo (independent variables) and the tissue composition of the carcass (dependent variable). In the light group there was correlation between LMD and FTP8 (0.54; D <0.01), ½ CARC (0.58; D <0.001), F (kg) (0.66; D <0.01) and F (%) (0.62; D <0.01), there was a negative correlation between the F (%) to the ratio M/F (-0.93, D <0.001), this may be due to M. Longissimus presenting delayed maturation and to the pantaneiro sheep depositing fat sooner when compared with other meat production specialized breeds. In the heavy group there was correlation between SFT with F (kg) (0.56; D <0.001) and F(%) (0.51; D <0.05), this measure is related to the carcass finish, for the deposition of fat in the 12th and 13th is later than in the rump. The independent variable that individually stood out in the light group prediction model was the (FTP8) and in the heavy group the (SFT). Ultrasonographic measurements in real time can be used as predictors of tissue composition. The fat thickness of the rump is the most important ultrasonographic measurement for the development of the light group prediction model.