Fat metabolism and regional distribution in ruminants and pigs-influences of genetics and nutrition

In this review we first discuss the role of intramuscular fat as a factor affecting consumer preferences for unprocessed pork, beef and lamb meat. The development of intramuscular fat in beef cattle, sheep and pigs is discussed in relation to increasing carcass weight and the potential for muscle growth. It is argued that muscle development and total carcase fatness play the primary role in determining the degree to which intramuscular fat accumulates. In older animals such as mature ewes, fat turnover is also likely to exert a significant influence. The elusive target is to influence partitioning of fat between different fat depots. The influence of nutrition on the expression of intramuscular fat is discussed with the general conclusion that it is difficult to influence intramuscular fat independently of that of other depots. However, new data is presented to show that the biochemistry of intramuscular adipocytes is significantly different to that of other depots and further research will be needed to understand the significance of this.