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Title: THE EFFECT OF INFUSION OF UREA INTO THE VENA CAVA ON FEED INTAKE OF FINISHING GILTS.

Author
item CHEN, H - UNIVERSITY OF NEBRASKA
item LEWIS, AUSTIN - UNIVERSITY OF NEBRASKA
item MILLER, PHILLIP - UNIVERSITY OF NEBRASKA
item Yen, Jong Tseng

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Feed intake of growing-finishing pigs is reduced when the protein concentration of the diet is increased above the protein requirement. However, the mechanism whereby an excessive amount of dietary protein causes decreased feed intake is unclear. The decrease in growth rate and feed intake of pigs fed high-protein diets is associated with elevated concentrations of plasma and blood urea. It seems possible that at some point plasma urea may reach a concentration that causes negative metabolic effects and that this provides a signal to the pigs to reduce feed intake. Litter information is available on the feed intake of pigs in which the concentration of plasma urea has been deliberately manipulated. The present study showed that plasma urea concentrations of pigs increased with increasing amount of urea infused. A daily infusion of 24 g of urea resulted in a plasma urea concentration similar to that of the pig fed the 25% crude protein diet. There was a trend for urea infusion to decrease daily feed intake in pigs and pigs infused with 30 g of urea a day consumed less feed than pigs infused with saline. These results indicate that plasma urea concentrations are involved in regulating feed intake of pigs ingesting high-protein diets.

Technical Abstract: Three experiments were conducted to evaluate the relationship between feed intake and plasma urea concentration. In Experiment 1, five gilts were fed a 16% crude protein (CP) corn-soybean meal diet and were infused continuously, through cannulae in their venae cavae, with either saline or one of four doses of urea (6,12,18,and 24 g/d) during each of five periods (12 h/period). The sixth pig was fed a 25% CP diet and infused with saline during each of the experimental periods. Plasma urea concentration increased with increasing amount of urea infused. A daily infusion of 24 g of urea resulted in a plasma urea concentration similar to that of the pig fed the 25% CP diet with saline infusion. In Exp. 2, pigs received a 16% CP diet and a different treatment (saline or 24 or 30 g/d of urea) in each of three infusion periods. Each infusion period lasted 2 weeks. Blood samples were obtained before infusion and daily after infusions started. Feeders were weighed daily to determine average daily feed intake (ADFI). Experiment 3 was similar to Exp. 2, except that only two treatments (saline and 30 g/d of urea) were used. In both Exp. 2 and 3, plasma urea concentration increased linearly with increasing amount of urea infused. Overall, there was a trend for urea infusion to decrease ADFI, and pigs infused with 30 g/d consumed less feed than pigs infused with saline. Therefore, the data suggest that plasma urea concentration may play a role in regulating feed intake in gilts consuming excess protein.