In vivo rabbit carcass composition and longissimus dorsi muscle vol-ume prediction by real time ultrasonography.
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2008
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The real-time ultrasonography (RTU) was used to measure in vivo the Longissimus dorsi muscle (LM) volume and to predict carcass composition of 63 New Zealand White X Californian rabbits. Animals were scanned between 6 th and 7 th lumbar vertebrae with RTU equipment with a 7.5 MHz probe, then weighed and slaughtered. Chilled carcass and reference carcass weight (RCW) were recorded and carcass dissected into meat, bone and total dissectible fat. The LM volume measured by in vivo RTU (LMVU) was calculated by multiplying the LM area obtained in vivo by RTU between the 6 lumbar vertebrae by the loin length measured on live animals by palpation on bone anatomical basis of the end points. Equivalent measurements to those taken in vivo were obtained on the carcass and the LM volume was measured using a digital image analysis (LMVC) and directly in loin LM muscle by Archimedes principle (LMVAr). Single regression equations were used for the estimation of carcass composition and LM volume (LMVC and LMVAr) using the LMVU measurement as independent variable. The carcass and in vivo measurements were also compared by ANOVA. The live weight varied from 1200 to 3410 g (average 2093 g) and the RCW from 472 g to 1773 g (average 997 g). Bone and total dissectible fat represented 78.0, 16.4 and 5.5% RCW, respectively. The LM measurements in carcass and in vivo by RTU were not significantly different for LM area and LM volume (LMVC). The LMVAr (57.4 cm 3 ) was lower (P<0.05) than LMVC (64.5 cm ) and LMVU (65.5 cm 3 ). Carcass and in vivo loin lengths differed significantly, being the carcass lower (11.2 cm; P<0.05) than the in vivo measurement (12.4 cm). Regression equations showed a strong relationship (P<0.001) between LMVU and the correspondent volume in carcass (r 2 =0.811 and 0.796 for LMVC and LMVAr, respectively). LMVU was also useful in predicting the amounts of carcass tissues (r 2 =0.801, 0.718 and 0.414 for meat, bone and total dissectible fat weight). Lower determination coefficients were obtained between LMVU and carcass tissues expressed in percentage of RCW (r from 0.003, P>0.05 to 0.329, P<0.001). In conclusion, carcass LM volume may be predicted from the loin length and LM area measurement obtained in vivo from a RTU scan between the 6 lumbar vertebrae, and the amount of carcass tissues can be predicted from LM volume measured in vivo by RTU. 3 th th and 7 and the 7 th 2 th
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Real time ultrasonography , Carcass , Longissimus dorsi volume , Rabbit