The effect of nutrition and exercise in carcass parameters and the level of glycogen in skeletal muscle of Merino sheep

Abstract

This study investigated the effects in sheep of feed intake and exercise training on (i) the level of glycogen in muscle, and (ii) carcass quality traits including growth rate, carcass weight, fat score, and the ultimate pH of muscle. Merino wethers, 12-months-old and starting body weight 38 kg, were individually penned and housed indoors. The effects of nutrition and exercise were tested for 2 levels of activity (sedentary v. exercised) and 4 levels of feed intake (1, 1.3, 1.5, 2.2 x maintenance) with 8 sheep per group housed individually. Exercise training was for 1 h at 8-9 km/h (approx. 55-65 VO2max), 3 times per week from week 4 to 9 of the experiment. The diet was 20% cereal straw, 26% lupin grain, 53% barley grain, mineral and vitamin premix, and virginiamycin. Animals were slaughtered at an abattoir in week 10. Regular exercise reduced growth rate, carcass weight, and fat score, but did not affect intake. At the highest level of intake, carcass weight was reduced by 0.53 kg and fat depth over the 12th rib (GR fat depth) by 6.3 mm, suggesting that muscle yield was increased. At all sampling times, the level of glycogen in the m. semimembranosis (SM) and m. semitendinosis (ST) increased linearly with increasing feed intake. Regular exercise caused increased glycogen level in SM samples immediately post-slaughter and in the SM, ST, and m. longissimus dorsi (LD) 48 h post-slaughter. The ultimate pH of muscle was reduced as the level of feed intake increased for all muscle groups. Exercise caused a reduction in the ultimate pH of the ST with no change for the SM and LD. The results indicate that glycogen levels in muscle are highly responsive to nutrition and regular exercise. In addition, exercise caused a reduction in subcutaneous fat with no change in feed intake.

Acute exercise increases insulin sensitivity in adult sheep: a new preclinical model

“…45). The similar muscle glycogen content measured in these animals in the unexercised state and 18 h after the exercise bout in ovine skeletal muscle in the present study is also consistent with a lack of training effect, since exercise training in sheep and in humans increases glycogen contents of resting skeletal muscle (33,36,40). It is possible, however, that the lack of change in glycogen content in skeletal muscle sampled 18 h after acute exercise in the present study might partially reflect incomplete restoration of glycogen depleted during exercise (54).…”

Facilitative glucose transporters in livestock species

“…Furthermore, in sheep, exercise training induces an increase in glycogen level in skeletal muscle, especially in muscles already containing a high amount of glycogen [74]. A similar response was found in the pig [33] and in other species (for review, see [43]).…”

Comparison of organoleptic quality and composition of beef from suckler bulls from different production systems

“…The post-mortem pH profile of a muscle is often associated with glycogen reserves prior to slaughter which in turn are related to the pre-slaughter stress experienced by the animal (Pethick et al, 1994, Pethick andRowe, 1996). In the present study, the bulls were unlikely to have experienced stress-induced glycogen depletion since they were finished indoors and accustomed to regular pre-slaughter handling.…”