Evaluation of diacylglycerol acyltransferase as an indicator of intramuscular fat content in beef cattle

The development of a biochemical or molecular marker for predicting the propensity for cattle to deposit intramuscular (i.m.) fat would reduce the time required to improve for this trait. In the current study, diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) activity was investigated as a potential biochemical marker for predicting the deposition of i.m. fat. The activities of DGAT were determined in microsomal fractions of subcutaneous (s.c.) adipose tissue, i.m. adipose tissue and muscle tissue sampled from Wagyu crossbred cattle at slaughter weight. The i.m. adipose and muscle tissues were dissected from the pars costalis diaphragmatis (p.c.d.) muscle. The lipid content (LC) of the p.c.d. muscle correlated with the LC of the longissimus muscle (r = 0.51; P < 0.05). There was an inverse correlation between p.c.d. i.m. adipose tissue DGAT specific activity and LC of the p.c.d. (r = -0.50; P < 0.05) suggesting that DGAT activity was down-regulated as i.m. adipose tissue became filled. There was a strong correlation (r = 0.74; P < 0.001) between DGAT total activity in i.m. adipose tissue and muscle DGAT total activity, suggesting DGAT activity is coordinately regulated in these two tissues.