Myostatin or growth and differentiation factor 8 (GDF8), has been known as the factor causing double muscling phenotypes in which a series of mutations make the myostatin protein inactive, hence disabling it to regulate the deposition of muscle fibre. This phenotype happens with high frequency in a breed of sheep known as the Texel. Quantitative trait loci (QTL) studies show that a portion of t...

Genetic correlations of selection indices and the traits considered in these indices with mature weight (MW) of Nelore females and correlated responses were estimated to determine whether current selection practices will result in an undesired correlated response in MW. Genetic trends for weaning and yearling indices and MW were also estimated. Data from 612,244 Nelore animals born between 1984...

The aims of this study were to investigate the impact of carcase estimated breeding values on carcase size and lean meat yield of lambs and to determine whether nutrition alters these responses. Selection for high estimated breeding values for growth increased carcase size by as much as 4 kg in lambs fed a high plane of nutrition. On a low plane of nutrition, this effect was reduced by 60%, hig...

We herein describe a procedure that allows for simultaneous genotyping of six loss-of-function mutations in the bovine myostatin gene associated with the double-muscling phenotype. The proposed method relies on a multiplex oligonucleotide ligation assay and detection of the fluorescently labelled products using automatic sequencers.

A visibly distinct muscular hypertrophy (mh), commonly known as double muscling, occurs with high frequency in the Belgian Blue and Piedmontese cattle breeds. The autosomal recessive mh locus causing double-muscling condition in these cattle maps to bovine chromosome 2 within the same interval as myostatin, a member of the TGF-beta superfamily of genes. Because targeted disruption of myostatin ...

The objective of this work was to determine the effect of sex, breed and birth season of calves on intensity of MLLT (musculus longissimus lumborum et thoracis) area changes and development of the selected body parts in bulls and heifers of Blonde d´Aquitaine (BA) cattle during rearing period. Two generations of bulls (n=63) and heifers (n=68) of Blonde d´Aquitaine (n=61) and crossbreds C×BA (C...

The aim of this experiment was to evaluate the impact of selection for greater muscling on whole body insulin responsiveness in cattle, as reflected by greater uptake of glucose in response to constant insulin infusion and greater glucose disappearance following an intravenous glucose tolerance test. This study used 18-month-old steers from an Angus herd visually assessed and selected for diver...