賴永裕 張秀鑾 劉錦條 李世昌 吳明哲
應用超音波即時顯像儀（Aloka SSD-500 B-模式）掃描不同月齡（4.0、4.5與5.0月齡）生長豬之第十肋骨處腰眼面積與同部位長軸中點1/2處背脂厚度，進而估計不同掃描日齡性狀間之遺傳參數與相關。同時，逢機選取150頭達110公斤之完檢豬隻，進行屠前活體重、第十肋骨處背脂厚度和腰眼面積，以及屠後體重、屠體長、平均背脂厚度、最後肋骨處背脂厚度、第十肋骨處腰眼面積、屠宰率與瘦肉率間之遺傳與表型相關探討。統計分析係以多性狀線性混合模式配合限制最大似然法（REML）估算變方與共變方成份，統計模式包括品種、性別、出生產次與出生季節等固定效應，以及累加性遺傳效應、同窩出生共同效應與殘差等逢機效應。結果顯示：不同月齡活體性狀表型變方估值隨月齡增加而增大；且除4.5和5.0月齡之活體背脂與5.0月齡體重外，其餘性狀之同窩出生之共同效應均較累加性遺傳效應大。同時，在本研究評估之各性狀中，累加性遺傳效應與同窩出生之全同胞顯性效應均佔表型變異50%以上。此外，由遺傳相關估值發現，完檢豬隻屠前活體掃描性狀與對應之屠體性狀均呈顯著的遺傳正相關（rG＝0.233 ~ 0.843，P＜0.05）；而經由Pearson相關分析所估得之表型相關估值，除屠前活體背脂與屠體腰眼面積為負值外(rP＝-0.184)，餘均與遺傳相關具相同的趨勢；惟各估值均較小（rG＝0.515 ~ 0.843 vs. rP＝0.443 ~ 0.622）。
GENETIC AND PHENOTYPIC CORRELATION AMONG
AND CARCASS MEASUREMENTS IN GROWING PIGS
Y. Y. Lai, H. L. Chang, C. T. Liu, S. C. Lee and M. C. Wu
Taiwan Livestock Research Institute, Council of Agriculture
Aloka Model SSD-500 B-mode real-time ultrasound scanner was used to scan growing pigs at 4.0, 4.5 and 5.0 months of age. Ultrasound measurements of loin muscle area at the tenth rib and 1/2 point overlying fat were taken for genetic parameter estimation and correlation analysis. 150 off-tested pigs near 110 ㎏ live weight were also randomly sampled to evaluate the genetic and phenotypic correlation for measurements taken before (live weight, ultrasound measurements of backfat and loin muscle area at the tenth rib) and after (carcass weight, carcass length, average backfat thickness, backfat thickness of the last rib, loin muscle area at the tenth rib, dressing percentage and lean percentage) slaughtered. Mixed linear model via REML for multiple trait analysis was used to estimate variance components. Model used included breed, sex, birth parity and birth season as fixed effects, additive genetic effects, common litter effects and error as random effects. Results showed that estimates of phenotypic variance for ultrasound measurements were increased as age increased. Larger common litter effects than additive genetic ones were observed in most of traits except in ultrasound backfat at 4.5 and 5.0 months of age, and weight at 5.0 months of age. Furthermore, additive genetic and common litter effects accounted for more than 50% of phenotypic variance for traits considered in this study. Positive genetic correlation were found between measurements taken before and after slaughter (rG＝0.233 ~ 0.843，P＜0.05) and similar trend was also obtained in Pearson correlation coefficients of phenotype except the one between backfat taken before slaughtered and loin muscle area of carcass (rP＝-0.184). However, the estimates of correlation were smaller in phenotype than in genotype (rG＝0.515 ~ 0.843 vs. rP＝0.443 ~ 0.622).
Key Words: Pigs, Genetic correlation, Ultrasound measurement, Carcass trait.