To predict body composition of growing Afshari fat-tailed lambs using the 9-11th rib composition as a predictor of whole body composition, 10 lambs were randomly selected (43.9 ± 3.9; mean shrunk body weight; mean ± SD) and harvested accordingly. After slaughter, the 9-11th rib sections were harvested from chilled carcasses for 24 h; fat, lean, fat-tail and bone were weighted separately and total separable fat (without fat-tail) and lean were grounded twice to obtain a homogenous sample for further chemical analysis. Rib dissection separable lean, fat and bone percent were (mean ± SD) 33.9 ± 6.6, 23.6 ± 6.6, and 17.3 ± 7.4, respectively. In addition, rib dissection ether extract, crude protein, moisture, and ash percent were (mean ± SD) 27.6 ± 4.1, 19.3 ± 0.7, 49.6 ± 5.3, and 1.7 ± 0.3, respectively. Except for carcass separable bone percent (with and without fat-tail), it was shown that the 9-11th physical rib composition can properly predict the carcass separable fat (adjusted R2 of 0.62 and 0.86 with and without accounting for fat-tail, respectively; P < 0.01) and lean (adjusted R2 0.77 and 0.71 with and without accounting for fat-tail, respectively; P < 0.01). As for the carcass chemical composition, with or without accounting for fat-tail, none of rib chemical commotion based on as-is analysis predicted chemical carcass composition. However, when as-is data were represented as soft tissue dry matter, only rib crude protein (%, without accounting for fat-tail) could predict carcass crude protein (adjusted R2 = 0.60; P < 0.005). In general, our results for the first time in fat-tailed sheep, showed that the 9-11th rib section can only predict physical, but not chemical, composition of fat-tailed lamb carcass.
