The purpose of this study was to determine the relationship between beta-carotene concentration and fatty acid profiles in meat of cattle sampled in two seasons. Jersey and Limousin cows were chosen for the experiment. Muscle samples from the Longissimus dorsi were collected and the beta-carotene concentration and fatty acid composition of the phospholipid fraction determined. Results demonstrated that compared to Limousin, Jersey had a higher concentration of beta-carotene, C16:1, C18:1(w-9) and total monounsaturated fatty acids, and a lower concentration of of the C18:2, C20:4, C24:1 and total polyunsaturated fatty acids.The beta-carotene concentration and most of the fatty acid profiles were influenced by season. Observed breed by season interactions in C18:2, C18:3(w-3), C20:4 and C24:1 fatty acids demonstrated that there are different seasonal influences in these two breeds. Significant residual correlations between beta-carotene concentration and C16:1, C18:0, C20:4 and C24:1 fatty acids may indicate a direct metabolic relationship between these components. Since it is known that beta-carotene can protect fatty acids against oxidation and influences sterol metabolism, the observed relationship may influence membrane function, meat fat colour, meat colour or possibly the storage of meat.
Records of cooking loss for M. longissimus dorsi and M. semitendinosus from a beef cattle experiment in New Zealand and Australia were analysed to test for linkage to DNA markers on all chromosomes except the sex chromosomes. This was part of a search for quantitative trait loci (QTL) for production, carcass and meat quality traits. Two extreme Bos taurus breeds, Jersey (J) and Limousin (L), were used to generate around 400 back-cross progeny in each country. For M. longissimus dorsi, there were four significant QTL for cooking loss (BTA 6, 7, 10, and 14) and three other locations where QTL effects approached significance (BTA 16, 24, and 25). There was also a QTL approaching significance on BTA 21 for cooking loss from the M. semitendinosus. The effects of L alleles relative to J alleles ranged from -0.66 to 1.42 phenotypic standard deviations (SD=1.8%) which would be sufficient to account for breed differences observed in other trials. None of the QTL were in regions homeologous to the RN or RYR1 genes in pigs that result in increased cooking loss.
Fat colour score (FCS), and carotene concentration and their relationships were examined in carcasses of Jersey, Limousin, and F1 heifers and in biopsy samples of Jersey, 3/4 Jersey, and 3/4 Limousin weaners. Results demonstrate significant differences between all breeds in carotene concentration and FCS. High correlations between FCS and B-carotene concentration were also demonstrated. Sex differences in FCS and B-carotene concentration were not significant. The shape of the distributions of beta-carotene content in fat varied between the breeds. High outliers were observed for the pure Jersey, 3/4 Jersey, and F1 and not observed in Limousin and 3/4 Limousin. Based on this preliminary data, we confirmed that beta-carotene concentration in fat of cattle has a genetic basis and hypothesise that a major gene(s) may be involved.
SUMMARY The Southern Crossbreeding Project was designed to examine a range of Bos taurus cattle breeds for production and beef quality traits. Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue sires were mated to Hereford cows with calves born over four years (1994-97). By testing two cohorts (1995-drop steers and 1996-drop heifers) representing 50 sires, it was concluded that there were no breed differences in tenderness or pH but there were differences in juiciness. Breeds high in intramuscular fat (Jersey and Wagyu) and the double-muscled Belgian Blue had less cooking loss than the other breed combinations.
Jersey and Limousin non-lactating cows were sampled at two different seasons to determine the beta-carotene
concentration and fatty acid profiles of subcutaneous adipose tissue. Results demonstrate significant differences between the Jerseys and Limousins in the concentration of beta-carotene and 14:1, 16:0, 18:1(w-7) and 18:3(w-6) fatty acids. Seasonal variations did not affect beta-carotene concentration but had a major effect on most fatty acids and ratios of fatty acid groups. There was no correlation between beta-carotene concentration and individual fatty acids which may indicate that there is no direct effect of beta-carotene on fatty acid metabolism.
SUMMARY The aim of this study was to investigate the relationships between various estimates of marbling in Jersey and Limousin crossbred steers with intramuscular fat percentage (IMF%) as determined by solvent extraction. The correlations between IMF% and various marbling scores ranged from 0.67 to 0.79. AUS-MEAT, MSA or USDA scoring systems were correlated, and ranked animals similarly. However, the best correlation with IMF% was found to be with the AUS-MEAT marbling score. When the range of IMF% was assigned to different scores within each system, the AUS-MEAT and USDA systems were similar whereas MSA scores had a higher concentration of fat per score and a broader range of concentrations. The only factors influencing assessment of marbling were IMF% and breed. Other traits, such as loin temperature, eye muscle area, melting point, fat colour and meat colour were not significant. Jersey cross steers had higher marbling scores (1.9 vs 0.8) and IMF% (6.4 vs 4.4%) than Limousin cross. A breed by sire interaction in marbling was also detected.
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