母豬群經長年生長選拔後之產仔性狀遺傳趨勢

自1981至1997年間以生長性狀為選留條件的純種母豬群，其分娩總仔數（LS）、分娩活仔數（LSA）與三週齡窩仔數（LS3）之遺傳趨勢與遺傳參數估計，係利用藍瑞斯891頭、約克夏500頭與杜洛克種586頭於1982至1998年間分娩的6593胎產仔資料，應用多性狀線性混合模式配合限制最大似然法（REML）估算各項變方與共變方成份，模式包括品種、分娩產次、母豬出生與其分娩季節（涼與熱季）等固定效應，而母豬之累加性遺傳效應、同窩出生共同效應與殘差等為逢機效應。LS、LSA與LS3遺傳變異率估值為0.091、0.099與0.095，同窩出生之共同環境效應估值為0.047、0.033與0.024。性狀間遺傳相關估值均在0.85以上（0.863～0.938）。LS、LSA與LS3具顯著的品種與分娩產次效應，且母豬的出生與分娩季節對其產仔性能LSA與LS3均有顯著的影響；出生或分娩於涼季的母豬顯著地有較大的出生活仔數與三週齡窩仔數。產仔性狀的遺傳趨勢佔其表型趨勢之百分率，在藍瑞斯、約克夏與杜洛克種分別為59.6～75.5％、46.4～62.9％與59.7～85.7％。表型與遺傳趨勢均呈現下降的趨勢（-0.083～-0.031與-0.132～-0.049頭／窩／年），表型方面以約克夏種（-0.132頭／窩／年）之年下降幅度為最大；遺傳趨勢部份，除LS3外，亦以約克夏種（-0.083頭／窩／年）之年下滑幅度為最大，間接地說明生長選拔會導致產仔能力的下降。

關鍵字

種豬；遺傳趨勢；遺傳參數；產仔性能

並列摘要

Genetic trends of reproductive performance in a sow herd selected for growth traits from 1981 to 1997. Litter traits were litter size at birth (LS) and born alive (LSA) as well as litter size at 3 weeks of age (LS3). Mixed linear model via REML was employed for estimation of variance-covariance components on litter tratis. Model for individual genetic evaluations included breed, parity, birth and farrowing seasons of sows as fixed effects, and additive genetic effects, common litter effects and error as random effects. Record of littering performance data on 891 Landrace, 500 Yorkshire and 586 Duroc pigs in Taiwan Livestock Research Institute between 1982 and 1998 were used. A total of 6593 litters from 1977 sows born between 1981 and 1997 were analyzed. Estimates of heritability from additive genetic variances for LS, LSA and LS3 were 0.091, 0.099 and 0.095. The corresponding estimates for common litter effect were 0.047, 0.033 and 0.024, respectively. Genetic correlation estimates were larger than 0.85 among traits considered (0.863 ~ 0.938). LS, LSA and LS3 differed among breeds and parities. Significant seasonal effects were also found in LSA and LS3. Sows born or farrowing in cool season produced larger LSA and LS3 than those in hot season. Genetic trends of litter traits accounted for 59.6~75.5%, 46.4~62.9% and 59.7~85.7% of phenotypic trends in Landrace, Yorkshire and Duroc breeds, respectively. However, both estimates of phenotypic and genetic trends for litter traits considered were negative (-0.083 ~ -0.031 and -0.132 ~ -0.049 piglets/litter/year). Yorkhsire sows showed the largest yearly phenotypic decrease (-0.132 piglets /litter/year). Similar trend was also observed in genetic evaluation among sow breeds except LS3 and the largest yearly decreasing rate was shown in Yorkshire sows (- 0.083 piglet /litter/year). Results implied that selection on growth performance would reduce the sow's littering performance.

並列關鍵字

Swine breeding stock ； Genetic trend ； Genetic parameter ； Littering performance

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