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Excess crude protein for finishing barrows and gilts
Abstract
Five experiments were conducted to investigate the effects of excess protein on growth performance, carcass characteristics, plasma urea concentration (PUC), organ weights, and liver arginase activity of finishing barrows (B) and gilts (G). In Exp. 1, 35 B and 35 G were fed diets containing 13, 16, 19, 22, or 25% CP. The comparative slaughter technique was used. Growth performance and PUC data were collected weekly from 51 to 115 kg BW of pigs. Thirty pigs were slaughtered at the end of the experiment to determine carcass merit and organ weights. In Exp. 2, 18 B and 18 G were fed either a 16 or a 25% CP diet from 63 to 105 kg BW of pigs. Performance and PUC data were collected weekly and liver samples were obtained at the end of the experiment. In Exp. 1, increasing protein level resulted in decreased ADG (linear, P $<$.10) and ADFI (linear, P $<$.05), and the reduction was greater in G than in B (P $<$.05). Backfat depths and fat accretion decreased linearly, whereas protein accretion increased quadratically (P $<$.10) as protein level increased. Increased protein levels resulted in increased liver, kidney, and pancreas weights (linear, P $<$.05). The response of PUC to dietary protein levels was significantly different between B and G (P $<$.05). Plasma urea concentration increased with each protein level with the exception of the 25 vs 22% CP groups in G. In Exp. 2, a sex $\times$ protein interaction was detected in ADG. Barrows had lighter liver weights (P $<$.005), greater arginase activity and PUC (P $<$.05). Increased protein level resulted in increased liver weight, arginase activity, and PUC (P $<$.005). In Exp. 3, six gilts (BW 53 kg) with cannulae in their vena cava were used to determine the amount of infused urea needed to mimic the PUC of pigs fed a 25% CP diet. Five G were fed a 16% CP diet and infused continuously 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 gilt was fed a 25% CP diet and infused with saline. Venous blood samples were obtained at 1-h intervals starting 1h before infusion. In Exp. 4, 12 G (BW 60 kg) received a 16% CP diet and a different treatment (saline or 24 or 30 g/d of urea) in each of three infusion periods (2 wk/period). Blood samples were obtained before and daily after infusion started. Feeders were weighed daily to determine ADFI. Experiment 5 was similar to Exp. 4 except that only two treatments (saline and 30 g/d of urea) were used. Plasma urea concentration increased with increasing amount of urea infused. Pigs infused with 30 g/d of urea consumed less (P $<$.05) feed than pigs infused with saline. The data suggest that G are more sensitive than B to excessive intakes of protein. The more negative effects in G may be related to liver metabolic capacity and activity of urea cycle enzymes. The increases in organ weights indicate that maintenance energy requirements may be increased as dietary protein concentration is increased.
Subject Area
Livestock|Anatomy & physiology|Animals
Recommended Citation
Chen, Hsin-Yi, "Excess crude protein for finishing barrows and gilts" (1998). ETD collection for University of Nebraska-Lincoln. AAI9838590.
https://digitalcommons.unl.edu/dissertations/AAI9838590