Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2001
Publication Date: 1/4/2002
Citation: SHORT, R., MACNEIL, M.D., GROSZ, M.D., GERRARD, D.E., GRINGS, E.E. PLEIOTROPIC EFFECTS IN HEREFORD, LIMOUSIN, AND PIEDMONTESE F2 CROSSBRED CALVES OF GENES CONTROLLING MUSCULARITY INCLUDING THE PIEDMONTESE MYOSTATINALLELE. JOURNAL OF ANIMAL SCIENCE. 2002. v. 80. p. 1-11. Interpretive Summary: Hereford-based production systems produce high-quality beef with few associated problems and are adaptable to a wide range of conditions. Increased production of lean beef while maintaining tenderness can be accomplished to a moderate degree by utilizing breeds such as Limousin. More dramatic effects can be obtained with Piedmontese through the effects of the mutant myostatin gene that causes double muscling. The effects of this mutant gene for some traits is additive, but many traits also have some form of a nonadditive gene action. Opportunities exist to exploit the positive effects of increased muscularity, but care must be taken to account for all effects. Use of Limousin could be through normal crossbreeding and selection schemes. Advantages of Piedmontese and the msP allele would be best captured through more complex breeding and selection programs that would lessen potential negative effects on some traits and through marketing systems which do not penalize for very low fat.
Technical Abstract: Hereford (H), Limousin (L), and Piedmontese (P) sires were bred to crossbred cows at random to produce F1 calves. The F1 progeny were inter se mated within sire breed to produce F2 calves. Piedmontese-cross calves were genotyped for the G-A transition mutation at the myostatin locus characteristic of P (msP), and their genotypes were classified on the basis of having 0 (P0), 1 (P1), or 2 (P2) copies of msP which resulted in five genotype classifications (H, L, P0, P1, and P2). Limousin-cross calves had heavier birth (but dystocia was not affected) and weaning weights, gained faster, had more muscle, less fat, larger pelvic area, and more efficient feed conversion than Hereford-cross calves. Piedmontese-cross calves (P0) were similar to Hereford-cross calves except that they required less assistance at birth in heifer dams, had less fat, gained slower, were less efficient, and had larger pelvic area. Addition of msP alleles (P1 and P2) consistently increased muscle, decreased fat, and increased adjusted efficiency, but many of those changes were not linear. We conclude that differences in muscularity affect most traits, and when differences in muscularity include the msP allele, there is an incremental, but not equal, change in most traits with the addition of each copy of the msP allele. Advantages of L could be captured through normal crossbreeding and selection schemes but with some caution because of potential problems that may surface from the increased variability. Advantages of P would be best captured through more complex breeding and selection programs that would lessen potential negative impacts and through marketing systems which do not penalize for very low fat.