Effect of Maternal Undernutrition on Connective Tissue Content of Fetal Skeletal Muscle of Hill and Lowland Breeds of Sheep

The early fetal environment such as maternal nutrition plays an important role in the development of skeletal muscle that is composed of both muscle and connective tissues. Hill ewes are adapted to harsh environments and can cope better with poor nutrition compared to lowland ewes. The present study investigated the effect of maternal undernutrition on primary fiber number of muscle as well as the connective tissue content in fetal skeletal muscle of both hill and lowland breeds of sheep. Hill (Welsh Mountain) and lowland (Dorset) ewes were used in 2 different experiments with one year interval. Experimental design, nutritional treatments and methods were same in both experiments. Ewes were mated and assigned as either control or undernourished group for each experiment. In each experiment controls were fed 100% of their daily nutritional requirement throughout experiment whereas undernourished ewes received 70 % of their daily nutritional requirement from day 22 to day 65 of gestation.All fetuses were taken out on 65th day of gestation by overdose injection of pentabarbitone. Fetal weight, fetal crown-rump length were measured. The semitendinosus muscle was dissected and sections were stained for alkali ATPase and hematoxylin eosin stain. Muscle cross sectional area, the percentage of muscle and connective tissue, the number of primary fibers and nuclei were measured. In lowland breed, the fetal weight and fetal weight: fetal crown-rump length ratio were significantly greater in undernourished group (P < 0.05). Furthermore, underfed fetal skeletal muscle of lowland breed had significantly larger cross sectional area and higher percentage of connective tissue (P < 0.05). It is concluded that maternal undernutrition seems to increase the connective tissue content of fetal muscle of lowland but not that of hill breed of sheep.