VLS_GUY":3vfqqfvw said:
The most these type of cattle have to walk is on level ground on a tame pasture. Most of the time they are housed. The BB I saw here panting while lying down like a winded dog when it was 90 degrees out. The idea of these cows rustling or bulls covering cows on rough ground falls under the heading of notgunnahappen.com.
Anther big problem these double muscled cattle do not breed well. Delayed sexual maturity and poor fertility are the order of the day.
The demand for the lean beef from such animals stems at least in part from different cooking methods used and the feeling that buying fat is like buying waste. Also keep in mind that fatty beef is problem for people on fat restricted diets this would make for a natural market for such animals. The beef is also very tender due to the muscle fibers being larger for the same amount of connective tissue. The production problems for use in extensive systems are very large however. Right now the typical American herd could get plenty of improvement by using normal continental reeds with out double muscling.
Not all double muscle genes are the same! There is no correlation with poor growth delayed sexual maturity and calving difficulty that you claim with the F94L gene which is located with the limousin population, The Belgian blue gene GDF8 does contribute to calving difficulty and fertility issues. the GDF8 gene is found in some charolais populations,.This study investigated the effects of a SNP in the myostatin gene (MSTN or growth differentiation factor 8, GDF8) on birth, growth, carcass, and beef quality traits in Australia (Aust.) and New Zealand (NZ). The SNP is a cytosine to adenine transversion in exon 1, causing an amino acid substitution of leucine for phenylalanine(94) (F94L). The experiment used crosses between the Jersey and Limousin breeds, with the design being a backcross using first-cross bulls of Jersey x Limousin or Limousin x Jersey breeding, mated to Jersey and Limousin cows. Progeny were genotyped for the myostatin SNP and phenotyped in Aust., with finishing on feedlot (366 calves, over 3 birth years) and in NZ with finishing on pasture (416 calves, over 2 birth years). The effect of the F94L allele (A allele) on birth and growth traits was not significant. The F94L allele in Limousin backcross calves was associated with an increase in meat weight (7.3 and 5.9% of the trait mean in Aust. and NZ, respectively, P < 0.001), and a reduction in fat depth (-13.9 and -18.7% of the trait means on live calves (600 d) and carcasses, respectively, Aust. only, P < 0.001), intramuscular fat content (-8.2% of the trait mean in Aust., P < 0.05; -7.1% in NZ, not significant), total carcass fat weight (-16.5 and -8.1% of the trait mean, Aust. and NZ; P < 0.001 and P < 0.05, respectively). Meat tenderness, pH, and cooking loss of the M. longissimus dorsi were not affected by the F94L variant. In the Jersey backcross calves, additive and dominance effects were confounded because the F94L allele was not segregating in the Jersey dams. The combined effects, however, were significant on LM area (4.4% in both Aust., P < 0.05, and NZ, P < 0.01), channel fat (-11.7%, NZ only, P < 0.01), rib fat depth (-11.2%, NZ only, P < 0.05), and carcass fat weight (-7.1%, NZ only, P < 0.05). The results provide strong evidence that this myostatin F94L variant provides an intermediate and more useful phenotype than the more severe double-muscling phenotype caused by knockout mutations in the myostatin gene.cattle with the f94l are more tender here is a link
http://www.sciencedirect.com/science/ar ... 4008002313
