張伸彰 黃雅芬 李錦足 涂海南 陳芳男 李世昌 顏念慈 吳明哲 張秀鑾
DEVELOPMENT OF PROLIFIC LINE IN SWINE I.
TRAITS OF MEISHAN CROSSING WITH DUROC
S. C. Chang, Y. F. Huang, F. C. Lee, H. N. Twu, F. N. Chen, S. C. Lee, N. T. Yen, M. C. Wu and H. L. Chang
Taiwan Livestock Research Institute, Council of Agriculture
Sow productivity is a major component of the production efficiency in pig industry. Litter size at birth and pre-weaning survival rate are the major component traits. However, these traits are difficult to improve through selection due to their low heritabilities. Crossbreeding could be another way to increase sow productivity by taking advantage of high prolificacy in some native Chinese breeds such as Meishan. The purpose of this study was to evaluate the littering performances of Meishan(M), Duroc(D) and reciprocal crosses(MD and DM defined as M sows sired by D boars and D sows sired by M boars, respectively) for the reference of the outstanding reproductive breeds selection in Taiwan. A total of 36 boars(including 12 M and 24 D breeds, respectively) and 95 sows(including 53 M and 42 D breeds, respectively) were used to produce 122 litters(95 and 27 litters produced at first and second parities, respectively) during 1997 and 1999. The data included 18, 14, 50 and 40 litters of M, D, MD and DM, respectively. Traits evaluated were litter size at birth(LS), born alive(LSA), at three weeks of age(LS3) and at weaned (LSW), litter weight born alive(LTRWT), average piglet weight at birth(WT0), at three weeks of age(WT3) and at weaned(WWT), piglet survival at birth(SURV1＝LSA/LS) and at three weeks of age(SURV2＝LSA/LS3). Results showed that sow breed effects was significant for littering traits considered and M sows had larger LS, LSA, LS3 and LSW than D females (P<0.001). However, piglets produced by D sows had heavier WT0, WT21 and WWT than those produced by M sows(P<0.001）. Also, the heterosis in LS3, LSW, SURV1, SURV2, LTRWT, WT0 and WT21 for MD and DM were significant (P<0.05）with estimates being 30.1%, 30.0%, 17.5%, 13.5%, 22.4%, 7.8% and 10.5%, respectively。
Key Words: Meishan pigs, Duroc pigs, Reciprocal crosses, Littering performances.