mRNA levels of the calpain system in longissimus muscle of young pigs during prolonged feeding of a protein-free diet.

This experiment was conducted to investigate the effects of feeding a protein-free diet on mRNA levels of the calpain system in skeletal muscle of growing pigs during a 15-d feeding trial. Twenty crossbred barrows were divided into two dietary treatments: control or protein-free diet (mean initial weight for both groups: 38.3 kg).

Comparison between 3-methylhistidine production and proteinase activity as measures of skeletal muscle breakdown in protein-deficient growing barrows.

This experiment was conducted to determine the relationship between 3-methylhistidine (3MH) production and proteinase activity in skeletal muscles of growing barrows. Barrows at 13 wk of age were randomly assigned to either control diet available on an ad libitum basis (21% of ME consisted of protein; control group), control diet fed restricted (pair-fed with barrows in protein-free group; intake-restricted group), or protein-free diet available on an ad libitum basis (protein-free group) for 14 d. During the last 3 d, blood samples were collected for determination of 3MH production rate, which is a measure of myofibrillar protein breakdown.