In vivo estimation of goat carcass composition and body fat partition by real time ultrasonography

¹ Escola Superior Agrária de Bragança. Centro Investigação de Montanha. P.O. box 172. Zip code 5301-855. Bragança, Portugall
² Unidad de Tecnología en Producción Animal, CITA, Zaragoza, Spain

^* To whom correspondence should be addressed. E-mail: teixeira{at}ipb.pt.

	Abstract

The accuracy of ultrasound measurements to assess goat carcass composition and the partition of body fat depots was evaluated. A Toshiba Sonolayer provided with a 5 MHz probe and image analysis was used to assess in vivo fat thickness and muscle depth in 56 Spanish Celtiberica adult goats, in lumbar and breast body regions. All the goats were slaughtered and the weight of body fat depots recorded. Measurements corresponding to the in vivo ultrasound fat thickness and muscle depth were taken on carcasses. The left sides of carcasses were completely dissected into their components. The best relationships (r = 0.94, P < 0.01) between in vivo and carcass measurements of fat thickness were obtained when they were taken at the sternum, and the best anatomical point was located between third and fourth sternebrae. The best correlation coefficients (r = 0.84) for muscle depth were found for measurements taken between the 3rd and the 4th lumbar vertebrae at 2 cm from the middle of the vertebral column. Body weight and the ultrasound measurements were used to fit the best multiple regression equations to predict carcass composition and the partition of body fat depots. All equations, with the exception of muscle quantity, omental and total body fat depot amounts were computed after performing a logarithmic transformation. BW in association with the ultrasound measurement taken at largest LM muscle depth, between the 1st – 2nd lumbar vertebrae accounted for 90 % of the muscle weight. BW was the first variable admitted into the prediction models of muscle, mesenteric fat and total body fat and accounted for 82, 67 and 79 % of the variation in tissue weights, respectively. The ultrasound measurement of fat thickness taken at the 3rd sternebrae was the first variable admitted into the prediction models for intermuscular fat, kidney and pelvic fat and the total carcass fat and accounted for by 73, 75, 71 and 79 % of the variation in the weight of these fat depots, respectively. The ultrasonic measurements taken in breast region, particularly at the 3rd and 4th sternebrae were the most suitable for assessing fat thickness. The results of this experiment suggest that the BW associated with some in vivo ultrasonic fat measurements allow predicting accurately the goat carcass composition and the body fat depots. Key words: body fat, carcass composition, goat, ultrasound.

Key Words: body fat, carcass composition, goat, ultrasound