Cellular characteristics of skeletal muscle in selected strains of pigs and mice and the unselected controls
Ezekwe, M.O.; Martin, R.J.
Growth 39(1): 95-106
1975
ISSN/ISBN: 0017-4793 PMID: 1132778 Document Number: 86835
Skeletal muscle growth of pigs differing in growth rate and muscularity was studied by analysis of DNA, RNA and protein in the semitendinosus muscle of fast-growing domestic lean pigs (Yorkshire) and slow-growing, feral obese pigs (Ossabaw). Both lean and obese strains were fed ad lib. and slaughtered at 6 mth of age. Yorkshire pigs had significantly greater body and muscle weights than the Ossabaw. RNA/DNA and protein/DNA ratios were significantly different between the Yorkshire and Ossabaw pigs. These data suggest that the greater muscle growth in the Yorkshire pigs is achieved by greater cell numbers and size.The response of skeletal muscle cells and fibre characteristics to selection was studied in 2 mouse strains by analysis of DNA, RNA and histological measurement of muscle fibres. Both strains were fed ad lib. They were sacrificed at 12 mth of age. Leg muscle DNA and RNA were significantly greater in the mice selected for rapid growth rate compared to the controls. Measurements of the semimembranosus muscle revealed that the growth strain had significantly greater muscle weight and muscle length than the control strain. Histological measurements of the same muscle showed that the growth strain had significantly greater fibre number and larger fibre size than the controls. It would appear that the greater muscle cellularity (DNA) in growth-strain mice is accompanied by greater muscle length, fibre number and fibre diameter.