Progress in DNA marker studies of beef carcass composition and meat quality in New Zealand and Australia

Abstract

Two beef cattle DNA-marker trials in New Zealand and Australia are reviewed, where the trial objectives were to identify DNA markers for carcass composition and meat quality traits. The collaborative beef cattle project between AgResearch and Adelaide University is described in detail, and reference is also made to published data from the Australian ‘Cooperative Research Centre (CRC) for Meat Quality’ DNA-marker study. In the Beef CRC, F1 Charolais x Brahman bulls were mated to composite dams to breed experimental offspring. The AgResearch/ Adelaide study used two extreme breeds, Jersey and Limousin, with F1 Jersey x Limousin bulls mated to produce both backcrosses in both New Zealand and Australia. Detailed information is presented here from New Zealand only (416 animals), comprising firstly live-animal records including ultrasound fat- and muscle-depth data, metabolites from fat and muscle biopsies, and plasma cortisol at slaughter, secondly carcass dissection data and organ weights, and thirdly shear-force tenderness, pH measures and some detailed biochemistry from the right striploin. A whole-genome scan was carried out with an average of 185 informative microsatellite markers per sire (range 170-196), spread widely across the autosomes. Quantitative trait loci (QTL) were identified for 14 phenotypes (with a genome-wide threshold level of significance), from the New Zealand half of the data analysed, including composition traits (ultrasound, carcass and eye-muscle data), dressing %, bone weight, fat weight, meat tenderness, millicalpain, polled/horned status, and plasma cortisol. Corresponding data from the Beef CRC, which (from their interim publication) had detected 18 QTL for 54 carcass and meat quality traits (some markers above a significant lod-score threshold of 2.5), included birth weight, carcass weight and dressing %, saleable meat yield (kg), eye muscle area, marbling score, tenderness, rumpfat depth and fat colour. The sizes of significant effects for each New Zealand phenotype ranged from 2.0 to 31% of the respective trait means, and the Beef CRC effects ranged from 3.0 to 33%, although in both studies most traits (except for fat traits) were in the 3 to 10% range. Further opportunities for exploiting the results in the beef industry are discussed.