ABSTRACT
Continued improvement in animal agriculture efficiency is critical for maintaining sustainable poultry and livestock production. With feed representing 60-70% of the cost of raising an animal to market weight, feed efficiency remains a very important genetic trait in animal agriculture. As such, the efficiency of how that energy is produced and utilized ultimately contributes to cellular utilization efficiency – cellular efficiency. Across the spectrum of animal species, skeletal muscle accounts for approximately 50% of body mass, and when considered as an entire organ, skeletal muscle contributes between 25% and 40% of basal metabolic rate (Brand, 1990a; Zurlo et al., 1990; Rolfe et al., 1999). A quarter of total basal metabolic rate in an animal may be assigned to one component of mitochondrial function – proton leak (Rolfe and Brand, 1996; Rolfe and Brand, 1997). A clear link between breast muscle mitochondrial function and feed efficiency has been reported (Bottje et al., 2002; Bottje and Carstens, 2009). Thus, mitochondrial function in skeletal muscle can play a substantive role in overall efficiency.
