Rapid communication: polymerase chain reaction-restriction fragment length polymorphism in the bovine growth hormone gene

Polymorphisms in growth hormone gene and their associations with calf weight in Japanese Black cattle

The objectives of this study were to detect effective genetic polymorphisms of bovine growth hormone (bGH) gene associated with calf weight in Japanese Black cattle. Fifty-eight sires and 47 breeding cows were used to detect the polymorphisms in exons by single-strand conformation polymorphism (SSCP). Four homozygous and six heterozygous SSCP genotypes were identified in exon 5. Although each single nucleotide polymorphism (SNP) had been reported, these genotypes were caused by three SNPs at the nucleotide positions 2141, 2277 and 2291. Four haplotypes C-C-A, G-C-A, C-C-C and G-T-A were newly identified. It was suggested that other haplotypes not detected in this study may not exist, considering the allele frequencies reported in Bos taurus and Bos indicus, and the migrating process of native Japanese cattle. Thereafter, we examined associations between the detected polymorphic sites in exon 5 by PCR - restriction fragment length polymorphism and calf weight using 53 breeding dams and 135 calves. The birth weights of calves with haplotype G-C-A are significantly lighter and calves' weights produced by cows with such haplotype are also lighter at 30 days old, using regression analysis. Although further research is necessary, these results may serve as a useful criterion to select breeding stocks, especially in maternal abilities.

Lack of association of GH1 and POU1F1 gene variants with meat production traits in Piemontese cattle

Growth hormone (GH) and the Pit-1 transcription factor have been shown to be involved in the physiological mechanisms related to growth. The present study was carried out to investigate the possible association of the polymorphism at GH1 and POU1F1 loci with meat production traits in Piemontese cattle. Fourteen traits were considered, expressing growth (weight at 5, 7 and 11 months, daily gain), size [withers height (WH), trunk length (TL), chest girth (CG) at 12 months] and meat conformation [withers width (WW), shoulder muscularity (SM), loin width (LW), loin thickness (LT), thigh muscularity (TM), thigh profile (TP), bone thinness (BT)]. Data were analysed with a mixed model procedure to estimate the allele substitution and the dominance effects. The results did not provide evidence of association of GH1 and POU1F1 polymorphisms with the evaluated traits.

Association of growth hormone loci with milk yield traits in Holstein bulls

A pedigree analysis was used to investigate the association of bovine growth hormone loci with milk production traits of Holstein cattle. Holstein bulls were typed for three bovine growth hormone loci located in exon V, intron C, and the 3' region of the gene. Phenotypic data were daughter yield deviations for milk, fat, and protein yields and for fat and protein percentages. Analysis of linkage across families was applied to the data using one or two bovine growth hormone loci as markers linked to a putative biallelic quantitative trait locus. Estimated parameters were allele frequency, genotypic means, within-genotype standard deviation of a putative quantitative trait locus, and recombination fraction between the markers and the quantitative trait locus. Parameters were estimated by maximum likelihood techniques. The estimated frequency of the quantitative trait locus allele that decreased the value of the phenotype ranged from 0.1 for milk yield to 0.6 for protein yield. The estimated effect of an allele substitution at the quantitative trait locus, given in phenotypic standard deviation units, ranged from 0.75 for fat percentage to 1.6 for milk yield. The standard deviation within genotype ranged from 0.67 for fat yield to 0.87 for milk yield. The estimated recombination fraction was close to zero for protein percentage, indicating physical linkage between a quantitative trait locus affecting the trait and the bovine growth hormone loci.