Identification of quantitative trait loci for growth and carcass composition in cattle¹

Abstract

A genomic screening to detect quantitative trait loci (QTL) affecting growth, carcass composition and meat quality traits was pursued. Two hundred nineteen microsatellite markers were genotyped on 176 of 620 (28%) progeny from a Brahman x Angus sire mated to mostly MARC III dams. Selective genotyping, based on retail product yield (%) and fat yield (%), was used to select individuals to be genotyped. Traits included in the study were birth weight (kg), hot carcass weight (kg), retail product yield, fat yield, marbling score (400 = slight00 and 500 = small00), USDA yield grade, and estimated kidney, heart and pelvic fat (%). The QTL were classified as significant when the expected number of false positives (ENFP) was less than 0.05 (F-statistic greater than 17.3), and suggestive when the ENFP was <1 (F-statistic between 10.2 and 17.3). A significant QTL (F = 19; ENFP = 0.02) was detected for marbling score at centimorgan (cM) 54 on chromosome 2. Suggestive QTL were detected for fat yield at 50 cM, for retail product yield at 53 cM, and for USDA yield grade at 63 cM on chromosome 1, for marbling score at 56 cM, for retail product yield at 70 cM, and for estimated kidney, heart and pelvic fat at 79 cM on chromosome 3, for marbling score at 44 cM, for hot carcass weight at 49 cM, and for estimated kidney, heart and pelvic fat at 62 cM on chromosome 16, and for fat yield at 35 cM on chromosome 17. Two suggestive QTL for birth weight were identified, one at 12 cM on chromosome 20 and the other at 56 cM on chromosome 21. An additional suggestive QTL was detected for retail product yield, for fat yield, and for USDA yield grade at 26 cM on chromosome 26. Results presented here represent the initial search for quantitative trait loci in this family. Validation of detected QTL in other populations will be necessary.

Association of GH and IGF-1 polymorphisms with growth traits in a synthetic beef cattle breed

“…Bovine GH has been mapped to position 65.7 cM on chromosome 19 (Ihara et al, 2004). The hypothesis of a segregating QTL close to the bovine GH is not supported by the results reported in the literature, since the QTLs for growth or meat production traits where mapped to intervals that do not include bGH, as discussed in Casas et al (2003). The hypothesis that the effects of GH observed in the present study might result from a different polymorphism in this gene appears to be more acceptable, since other polymorphisms of this gene have been associated to growth traits in cattle (Taylor et al, 1998).…”

Search for quantitative trait loci affecting growth and carcass traits in a cross population of beef and dairy cattle1

“…The search for QTL affecting carcass yield and carcass composition in cattle has been mainly conducted by studying commercial half-sib families (Mizoshita et al, 2004;Mizoguchi et al, 2005) or experimental crosses [e.g., Bos indicus × Bos taurus (Stone et al, 1999;Casas et al, 2003) and Limousin × Wagyu cattle (Alexander et al, 2007)]. In the case of experimental cross populations, the QTL model used is based on the assumption that the founder lines are fixed for alternative alleles at the QTL (Haley et al, 1994).…”

Candidate genes for production traits in Nelore beef cattle

“…FABPs are members of a family of proteins that bind lipids. FABP4, also known as adipocyte FABP, is located on bovine chromosome 14 in which QTLs for the meat production traits fat thickness, yield grade, and marbling have been reported (Casas et al, 2003). Studies have shown that FABP4 plays a critical role in fatty acid absorption and metabolism and seems to be involved in the hydrolysis of lipids (Michal et al, 2006 of Michal et al (2006), who observed an association between this gene and marbling score and backfat deposition in a Wagyu x Limousin F 2 population.…”