| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 99 === Performance of domestic animals was influenced by environmental and genetic factors. Environmental factors, such as feeding management, transportation, and slaughtering procedure, and genetic factors, such as line effects, sex-linked intderitance also affect animal performance. Furmore, by crossbreeding, it is possible to obtain some heterosis results. Reciprocal cross, which interchanges the parents’ genders during breeding, can partially explain the influences due to the maternal effects and sex-linked inheritance. The objective of this study was to evaluate the effects of line effect, heterosis, and sex-linked inheritance on carcass and meat traits of chickens which were reciprocal crossed the Taiwan Country chicken L2 and the Rhode Island Red chicken (R-). The F1 generations which including 2 purebred cocks (LLM and RRM), positive reciprocal cross cock (LRM, L2 and R- were used as sire and dam, respectively), negative reciprocal cross cock (RLM, R- and L2 were used as sire and dam, respectively), positive reciprocal cross hen (LRF), and negative reciprocal cross hen (RLF), were slaughtered at 23rd weeks and analyzed. The results showed that most of the carcass characteristics were significantly influenced by the line effect and heterosis. Some heterosis were showed in the weights and weight percentage of some viscera, and possibly influenced by the maternal effect and sex-linked inheritance. Live weight, weights of carcass weight, wing, and leg were also influenced by the maternal effect and sex-linked inheritance. Some heterosis was illustrated in drumstick length and breast shape indexes, whereas R- purebred had higher feather and blood weights when compared to L2 purebred. Moisture and crude fat of breast were influenced by the maternal effects, and significant differences were observed in the fat contents of breast between the two purebreds. L* and a* values of breast were also influenced by the maternal effect, and heterosis was observed in a* values. R- purebred had the lowest postmortem pH 15 min values of breast, whereas L2 purebred had the highest pH decrease rates. pH 24 h was effected by sex-linked inheritance. Heterosis was observed in pH 48 h. The water-holding capacity of breast muscle was significantly influenced by the line effect. Shear value of breast muscle was affected by sex-linked inheritance. The myofibril numbers and cross-sectional areas were significantly influenced by the line effect. Myofibril numbers were also influenced by sex-linked inheritance. There was no significant difference in MFI due to the line effect, whereas MFI was affected by sex-linked inheritance. In conclusion, performance of carcass, meat quality, and muscle fiber traits were affected by the line effect, maternal effect and heterosis, whereas the line effect was the main facror to affect carcass traits. Significant heterosis was observed in some meat quality traits. Carcass, meat quality, and muscle fiber traits of hens could be affected by sex-linked inheritance.
|
|---|
