Relationship of mitochondrial energy production with the rate and efficiency of whole body growth in young growing animals
Associations between mitochondria function and the mitochondrial protein adenine nucleotide translocator 1 (ANT1) content with rate and efficiency of growth in young growing rats and pigs were evaluated. Mitochondria were isolated from the gastrocnemius muscle in rats (n = 43) and the biceps femoris muscle in pigs (n = 44) to measure mitochondrial protein content and function among animals from a single strain and rearing environment. Lower rates of mitochondrial proton leak-dependent respiration (State 4; r = 0.42, P < 0.01) or improved mitochondrial metabolic efficiencies (RCR; r = 0.33, P < 0.05) in skeletal muscle were associated with improved gain/feed ratios in rats. In addition, rats with a lower muscle mitochondrial protein content exhibited improved efficiencies of feed utilization (r = 0.43, P < 0.01) and improved rates of growth (r = 0.31, P < 0.05). In pigs, higher rates of maximal mitochondrial respiration (State 3; r = .43, P < .01), an improved RCR (r = 0.34, P < 0.05) and a greater amount of ANTI protein in the biceps femoris muscle (r = 0.44, P < 0.05) were each associated with improved daily body weight gains.;The ability of bilobalide and proanthocyanidins to positively modulate mitochondrial function also was evaluated. Weanling rats (16/trt) were allowed access to a diet containing either 0 or 78 ppm bilobalide for 22 days post-weaning. Gastrocnemius and liver mitochondria were isolated for mitochondrial function measurements. Dietary bilobalide addition resulted in increased liver weights (P < 0.01) and protein contents (P < 0.01), State 3 rates (P < 0.05) and RCR (P = 0.08) in liver mitochondria. However, mitochondrial function in the gastrocnemius muscle and daily BW gain, feed intake, and efficiency of feed utilization were not altered by bilobalide addition. In vitro incubation of pig skeletal muscle mitochondria with 0.36 mug/ml proanthocyanidins resulted in a 15% improvement (P < 0.05) in State 3 respiration. These data establish that variation in mitochondrial function exists and is important to both the rate and efficiency of whole body growth in animals and bioactive compounds may have the potential to positively alter mitochondrial function.