Dietary influence on organ size and in vitro oxygen consumption by visceral organs of growing pigs

Although visceral organs represent only about 15% of the pig’s body weight, they account for about 45% of whole body oxygen consumption. The effect of diet on organ mass and in vitro oxygen consumption by some visceral organs was investigated in a study using 15 Yorkshire male castrates (18.961.5 kg initial body weight). Diets were based on casein-corn starch (CC), barley-canola meal (BCM) or barley-canola meal–alfalfa meal (BCM-ALF) and formulated to contain 0.088 MJ digestible energy (DE) per gram of crude protein. Pigs were fed at 2.6 times maintenance DE requirements twice daily for 3 weeks, then every 3 h for 3 days prior to tissue sampling. One h after feeding, pigs were killed and samples of the liver, jejunum, colon and caecum taken immediately. In vitro oxygen uptake was determined polarographically using an oxygen electrode. Per kg empty body weight (EBW), weight of the small intestine did not differ (P . 0.10) between treatments. Per kg EBW, weights of liver, colon and caecum were higher (P , 0.05) in BCMand BCM–ALF-fed pigs than in CC-fed pigs. Weight-specific oxygen consumption by the liver tissue and intestinal mucosa was not influenced by diet (P . 0.10). However, weight-specific oxygen consumption was higher (P , 0.05) in the caecum muscularis of pigs fed BCMand BCM–ALF than in the CC-fed pigs. Per kg of EBW, total oxygen uptake by the colon of BCMand BCM–ALF-fed pigs was higher (P , 0.001) than in CC-fed pigs. The values for oxygen consumption by the liver in CCand BCM-fed pigs were similar (P . 0.10) and lower than those in the BCM–ALF-fed-pigs. In conclusion, changes in diet composition alter energy expenditure in the liver and intestinal tissue. This appears largely mediated via effects on organ size and not via weight-specific oxygen consumption.  2000 Elsevier Science B.V. All rights reserved.