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1

Genetic aspects of twinning in cattle

100%
Komisarek J., Dorynek Z.
Journal of Applied Genetics
|
2002
|
vol. 43
|
issue 1
55-68
EN
Twinning in cattle ranges from about 1% for beef breeds to about 4% for dairy breeds. The incidence of double births may have both positive and negative effects, which mainly depends on the purpose for which the cattle are raised. Because of freemartinism, as well as management problems connected e.g. with a greater risk of dystocia and retained placenta, it is an undesirable trait in dairy herds. In beef cattle, however, twinning can considerably increase the efficiency of production. Low heritability, a long generation interval for progeny testing, sex-limited expression and an unfavourable correlation with milk yield make twinning difficult to control by selection. Hence, it is the type of trait for which the identification of the genetic marker - quantitative trait loci (QTL) linkage and the implementation of marker-assisted selection in breeding strategies are expected to be especially beneficial. Searching for QTL influencing the reproductive rate in cattle was performed mainly in the US Meat Animal Research Center twinning herd and in the commercial Norwegian cattle population. Among several genome regions that appear to control twinning and ovulation rates, the most interesting seem to be chromosomes 5, 7, 19 and 23.
2

Effect of ABCG2, PPARGC1A, OLR1 and SCD1 gene polymorphism on estimated breeding values for functional and production traits in Polish Holstein-Friesian bulls.

100%
Komisarek J., Dorynek Z.
Journal of Applied Genetics
|
2009
|
vol. 50
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issue 2
125-132
EN
This study investigated the impact of 6 polymorphisms located in the ABCG2, PPARGC1A, OLR1 and SCD1 genes on estimated breeding values for milk production, longevity, somatic cell count and reproductive traits. The analysis was conducted on 453 Polish Holstein-Friesian bulls. Genotypes were identified using PCR-RFLP, and haplotype inferences were performed for 3 linked mutations of PPARGC1A. The most significant associations were found between the A/C polymorphism located in exon 14 of ABCG2 and milk fat production traits as well as calving-to-first insemination interval, and between the T/C substitution in intron 9 of the PPARGC1A and non-return rate in heifers.
3

Practical application of daughter yield deviations in dairy cattle breeding

81%
Szyda J., Ptak E., Komisarek J., Zarnecki A.
Journal of Applied Genetics
|
2008
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vol. 49
|
issue 2
183-191
EN
Daughter yield deviations (DYDs) of bulls and yield deviations (YDs) of cows, besides estimated breeding values (EBVs), are standard measures of animals' genetic merits in routine genetic evaluations worldwide. In this contribution, we first point out differences and similarities between DYDs and EBVs calculated for milk, fat and protein yields. While the latter measure represents the additive polygenic value of an animal, the former consists of both the additive polygenic and residual components. Then, a summary of DYDs and YDs calculated for the Polish population of dairy cattle is presented. The estimated correlations between DYDs and EBVs are generally high, but vary considerably depending on the minimum number of daughters used for calculation of DYDs and on the accuracy of calculated DYDs. Using DYDs estimated for each production year for 16 452 bulls, we demonstrate how to use DYDs for the validation of genetic trend estimated in the model used for genetic evaluation. Based on genotypic data of 252 bulls, we show that DYDs can be used for the estimation of candidate gene effects. For each of the yield traits, the within-bull genetic trend was relatively high, ranging between 1.39% of genetic standard deviation per production year for milk and 7.67% of genetic standard deviation per production year for fat, both in the 2nd lactation. Out of 8 polymorphisms tested, 5 showed a significant correlation with DYD, with the highest effect attributed to the polymorphism within the leptin receptor gene, whose additive effect was estimated as 247.33 kg of milk at 2nd parity.
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