Effect of castration on carcass quality and differential gene expression of longissimus muscle between steer and bull
The effect of castration on carcass quality was investigated by ten Chinese Simmental calves. Five calves were castrated randomly at 2 months old and the others were retained as normal intact bulls. All animals were slaughtered at 22 months old. The results showed that bulls carcass had higher weight (P < 0.05), dressing percentages and bigger longissimus muscle areas (P < 0.05) than steers. But steer meat had lower shear force values and was fatter (P < 0.05) than bull. Furthermore, in order to discover genes that were involved in determining steer meat quality, we compared related candidate gene expression in longissimus muscle between steer (tester) and bull (driver) using suppressive subtractive hybridization. Ten genes were identified as preferentially expressed in longissimus muscle of steer. The expression of four selected differentially expressed genes was confirmed by quantitative real-time PCR. Overall, a 1.96, 2.41, 2.89, 2.41-fold increase in expression level was observed in steer compared with bull for actin, gamma 2, smooth muscle, tropomyosin-2, insulin like growth factor 1 and hormone-sensitive lipase, respectively. These results implied that these differentially expressed genes could play an important role in the regulation of steer meat quality.
KeywordsSteer Bull Carcass quality Gene differential expression Longissimus muscle
The authors would like to thank the staffs of Changtu experiment station of Liaoning Province, the staffs of Lvfeng Food Company of Liaoning Province, and the technicians of Liaoning Provincial Breeding Cattle Center. This research was financially supported by the earmarked fund for Modern Agro-industry Technology Research System (No. nycytx-38), the New Variety of Transgenic Organism Great Breeding Program (NO. 2008ZX08007-002 and NO. 2009ZX08009-157B), the Eleventh ‘‘5 Year’’ National Science and Technology Support Project (NO. 2006BAD04A16 and NO. 2007BAD56B04), the National 863 Program of China (NO. 2008AA10Z146), and the Public Welfare Profession Research Program (NO. nyhyzx07-035-07).
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