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發表於 2013-10-11 21:03:02
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本帖最後由 蘇少儀 於 2013-10-11 08:06 編輯
豬隻繁殖性能研究發展
郭士逢
生物科技組 副研究員
財團法人台灣動物科技研究所
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出生重與整齊度
窩內出生活仔率與出生窩重為遺傳正相關(0.22 to 0.55)，與窩內出生重差異(整齊度)為遺傳負相關(-0.18 to -0.52)。對於出生窩重輕的品系選拔活仔率是可行的，提高出生個重或窩重均可提高活仔率。因此每個品系選拔適當出生重且窩內整齊度高，對整體仔豬存活與生長可得到最大的改善(Kapell et al., 2011)。
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J Anim Sci. 2003 Mar;81(3):604-10.
Genetic parameters for within-litter variation in piglet birth weight and change in within-litter variation during suckling.Damgaard LH, Rydhmer L, Løvendahl P, Grandinson K.
SourceDanish Institute of Agricultural Sciences, Department of Animal Breeding and Genetics. P.O. Box 50, DK-8830 Tjele, Denmark. [url=mailto ars.damgaard@agrsci.dk]Lars.damgaard@agrsci.dk[/url]
AbstractThe objective of this study was to ascertain whether maternal additive genetic variance exists for within-litter variation in birth weight and for change in within-litter variation in piglet weight during suckling. A further objective was to estimate maternal genetic correlations of these two traits with mortality, birth weight, growth, and number of piglets born alive. Data were obtained from Lövsta research station, Swedish University of Agricultural Sciences, and included 22,521 piglets born in 2,003 litters by 1,074 Swedish Yorkshire sows. No cross fostering was used in the herd. The following seven traits were analysed in a multivariate animal (sow) model: number of piglets born alive, within-litter SD in birth weight, within-litter SD in piglet weight at 3 wk of age, mean weight at birth, mean weight at 3 wk of age, proportion of stillborn piglets, and proportion of dead piglets during suckling. Maternal genetic variance for the change in within-litter SD in piglet weight during suckling was assessed from the estimated additive genetic covariance components by conditioning on within-litter SD in birth weight. Similarly, mean growth of piglets during suckling was assessed from the additive genetic covariance components by conditioning on mean weight at birth. The heritability for within-litter SD in birth weight was 0.08 and 0.06 for within-litter SD in piglet weight at 3 wk. The genetic correlation between these two traits was 0.71. Little maternal genetic variance was found for the change in within-litter SD in piglet weight during suckling, and opportunity for genetic improvement of this trait by selective breeding seems limited. The genetic correlation of within-litter SD in birth weight with proportion of dead piglets during suckling was 0.25 and of within-litter SD in birth weight with mean growth of piglets was -0.31. The maternal genetic variance and heritability found for within-litter SD in birth weight indicates that genetic improvement of this trait by selective breeding is possible. In addition, selection for sows' capacity to give birth to homogeneous litters may be advantageous for piglet survival, piglet growth, and litter homogeneity at weaning.
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Prev Vet Med. 2002 Dec 18;56(2):119-27.
Neonatal-piglet weight variation and its relation to pre-weaning mortality and weight gain on commercial farms.Milligan BN, Dewey CE, de Grau AF.
SourceDepartment of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, N1G 2W1, Ont, Canada. bmilliga@uoguelph.ca
AbstractTo determine the effect of within-litter neonatal-weight variation on pre-weaning mortality and weight gain, we analyzed piglet survival and weight gain within 400 litters from 10 commercial farms. Neonatal-weight variation (independent of mean neonatal weight, litter size and sow parity) was associated with pre-weaning survival and weaning-weight variation-but not with mean weaning weight. Neonatal piglets with weights well below the range of most of the litter (low-birth-weight piglets) had an increased risk of dying and were unable to obtain normal weight gains by weaning if they survived. These piglets experienced lower survival and poorer weight gain in larger litters. These piglets also tended to have lower survival but normal (albeit low) weaning weights if they survived in litters from middle-aged and old sows. High neonatal-weight variation resulted in lower survival and more variable weaning weights. Small piglets had a greater risk for poor survival and weight gain compared to their heavier litter-mates (a disadvantage that was exacerbated in large litters).
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以我對豬育種學粗淺的認識
Unknow兄所舉的例子是很有趣的例子
與A公豬配種,胎仔數少(8頭)而同窩整齊度差,與B公豬配種,胎仔數正常(11頭)而且窩整齊度佳.因為母豬相同,不同胎次間會有差異.而且不同公豬後代,會影響仔豬旳檢定指數.因此,A與B胎次的仔豬的檢定成績不同,並不意外
與A公豬配種生下仔豬中有一頭公豬檢定成績較佳,這也蠻有趣的,胎仔數小,通常離乳體重較重,而離乳體重也影響到日增重,但一般而言日增重佳的豬,背脂厚度會較厚.杜洛克背脂厚度的指數權重較高,會影響指數.因此此一比喻.................
這一個例子,有很多性狀是胎次間不能比較的(很多因子不是在同一個基礎上作比較)
舉例也是有學問的 |
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