Relationship between body condition score and subcutaneous fat and muscle area measured by ultrasound in Pelibuey ewes

Abstract

The body condition score (BCS) is the main measure used to determine nutritional and body status in the sheep industry, however, its evaluation is subjective and, both researchers and producers can easily fall into an overestimate or underestimate of this parameter. In consequence, this study aimed to assess if back fat thickness (FT) and Longissimus dorsi area (LDA) measured by ultrasonography can be used to develop prediction equations for BCS in multiparous and non-pregnant Pelibuey ewes. Eighty ewes were used to carry out the experiment. Experienced technicians developed the evaluation of BCS using a 5 point scale, as well as the measurements of FT and LDA in the thoracic and lumbar regions with real-time ultrasound equipment. The FT in the thoracic and lumbar regions ranged from 0 to 5.50 mm and the thoracic and lumbar LDA varied from 2.96 to 13.00 cm2. BCS had a positive moderate correlation (P<0.0001)with thoracic and lumbar FT (0.45≤ r ≤0.60), as well as with thoracic and lumbar LDA (0.65≤ r ≤0.67). Simple linear regression equations for BCS showed to be significant (<0.001) using ultrasound measurements as predictors, being a better predictor LDA (r2= 0.92) than FT (r2=0.21-0.36). Using multiple linear regression, the equation that included lumbar FT and LDA as independent variables showed to be the best (r2= 0.93, MSE= 0.76 and RSD= 0.87) to predict BCS. In conclusion, ultrasound measurements may be used to predict BCS, mainly LDA, in multiparous and non-pregnant Pelibuey ewes.