TAQI RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS FOR GROWTH-HORMONE IN BOVINE BREEDS AND THEIR ASSOCIATION WITH QUANTITATIVE TRAITS

The objectives of the present study were (1) to reveal GH-TaqI RFLPs i n different bovine breeds and (2) to look for association between quan titative traits and GH-TaqI RFLPs in bulls highly selected for growth and meat production. Blood was sampled from 269 Holstein heifers, 48 I talian and 45 Hungarian Simmental heifers, 30 Normande heifers and 41 bulls and 13 heifers of the double-muscled Belgian White Blue breed. B ulls were weighed from 7 until 13 months of age and the average daily gain, the feed efficiency, the height and the phenotypic index were de termined at the end of the experiment. GH-TaqI RFLPs revealed 4 DNA fr agments of 6 (A), 5.2 (B), 4.4 (C) and 4.2 (D) kbp. The distribution o f genotypes was different between Normande and the other breeds (P<0.0 01) and between Belgian White Blue and Holstein (P<0.001) or Hungarian Simmental breed (P<0.005). The Normande heifers were also characteriz ed by a high frequency of the AB genotype (53%) compared with other ex perimental breeds (range values: 7-24%). In the statistical analysis o f the relationships between quantitative traits and GH-TaqI RFLPs in d ouble-muscled Belgian White Blue bulls, the AC genotypic class was not used because of its low distribution. The AA class showed greater rec ords of weight at 7 (P<0.07) and 13 (P<0.06) months of age than the AB class. In conclusion, this study has shown a correlation between the GH-TaqI RFLPs and weight at 7 and 13 months of age in Belgian White Bl ue bulls. However, more definitive conclusions require larger number o f observations and quantitative data as devoid as possible from enviro nmental, nutritional and other sources of variation.