Relationship of the bovine growth hormone gene to carcass traits in Japanese black cattle.

The bovine growth hormone gene (bGH) possesses three haplotypes, A, B and C, that differ by amino acid mutations at positions 127 and 172 in the fifth exon: (leucine 127, threonine 172), (valine 127, threonine 172) and (valine 127, methionine 172) respectively. The correlation between meat quality or carcass weight and these haplotypes was investigated in Japanese black cattle. Altogether, 940 bGH haplotypes were compared with respect to six carcass traits: carcass weight, longissimus muscle area, rib thickness, subcutaneous fat thickness, beef marbling score and beef colour. The frequency of the B haplotype was higher (0.421) than that of A (0.269) and C (0.311). High carcass weight and low beef marbling were associated with haplotype A (p < 0.05 and p < 0.01 respectively), whereas beef marbling was increased by haplotype C (p < 0.05). Estimated regression coefficient of the A haplotype substitution effect for carcass weight and beef marbling score were 5.55 (13.1% of the phenotypic SD) and -0.31 (17.0%) respectively. That of the C haplotype for beef marbling score was 0.20 (11.0%). The other traits showed no relationship to the haplotypes examined. The results of this investigation suggest that information pertaining to bGH polymorphisms in Japanese black cattle could be used to improve the selection of meat traits.

Genetic mapping of the QTL affecting body weight in chickens using a F2 family.

1. To identify the quantitative trait loci (QTL) affecting growth in chickens, we carried out QTL analysis on chicken growth traits using a population of 227 F2 crosses between a Satsumadori (slow-growing, light-weight Japanese native breed used as a meat chicken) male and a White Plymouth Rock (early-maturing, heavy weight broiler). 2. We chose 78 microsatellite loci from 331 publicly available on 14 linkage groups, with respect to their utility and location. 3. Two QTLs affecting body weight at 13 and 16 weeks were mapped at 220 cM on chromosome 1 (LOD scores, 2.8 and 4.5, respectively, at 13 and 16 weeks), and at 60 cM on chromosome 2 (LOD scores, 6.2 and 8.1, respectively, at 13 and 16 weeks). 4. The closest loci to the QTLs were LEI71 on chromosome 1 and LMU13 and MCW184 on chromosome 2. 5. The sites of the QTLs agreed closely with those already reported. Therefore, it seems likely that QTLs affecting growth of chickens are located at these sites.

Chicken microsatellite primers are not efficient markers for Japanese quail.

Domestic fowl or chicken (Gallus gallus) and Japanese quail (Coturnix japonica) belong to the family Phasianidae. The exchange of marker information between chicken and quail is an important step towards the construction of a high-resolution comparative genetic map in Phasianidae, which includes several poultry species of agricultural importance. We tested chicken microsatellite markers to see if they would be suitable as genetic linkage markers in Japanese quail. Twenty-six per cent (31/120) of chicken primers amplified individual loci in Japanese quail and 65% (20/31) of the amplified loci were found to be polymorphic. Eleven of the polymorphic loci were excluded as uninformative because of the lack of amplification in some individuals or high frequency of nonspecific amplification. The sequence information of the remaining nine loci revealed six of them to contain microsatellites that were nearly identical with those of the orthologous regions in chicken. For these six loci, allele frequencies were estimated in 50 unrelated quails. Although the very few chicken markers that do work well in quail could be used as anchor points for a comparative mapping, most chicken markers are not useful for studies in quail. Therefore, more effort should be committed to developing quail-specific markers rather than attempting to adapt chicken markers for work in quail.