Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 18, 2006
Publication Date: June 1, 2006
Citation: Klindt, J.M., Thallman, R.M., Wise, T.H. 2006. Effects of sire line, sire, and sex on plasma urea nitrogen, body weight, and backfat thickness in offspring of duroc and landrace boars. Journal of Animal Science. 84(6):1323-1330. Interpretive Summary: Among the problems facing the swine industry are inefficient use of inputs, particularly dietary amino acids which account for approximately 25% of feed costs, and management and disposal of manure. Efficiency of dietary amino acid retention as lean tissue is low, often less than 40%. Unretained amino acids are converted to urea and excreted in urine. Feeding dietary nitrogen or protein in excess results in high plasma urea, which is excreted in the urine and subsequently converted to ammonia, a volatile pollutant. Thus, problems of manure management are inextricably associated with inefficient use of dietary nitrogen. A study was conducted to quantify the effect of sire breed, sire, and sex on plasma urea and growth rates in swine to assess whether plasma urea concentrations are genetically determined and are a potentially exploitable quantitative trait. Sire line, sire, sex, and age affected body weight, backfat thickness and plasma urea concentrations over the growing-finishing period. Analysis of the genetic parameters revealed heritability estimates for plasma urea was moderate, 0.35, and the phenotypic and genetic correlations of mPUN with other traits were low to moderate. Plasma urea may be an exploitable quantitative or additive trait that can be capitalized to improve efficiency of dietary protein utilization in, and reduce negative impacts of pork production on the environment.
Technical Abstract: In pork production, efficiency of dietary protein (nitrogen) utilization is low, often less than 40%, resulting in urinary excretion of large quantities of nitrogen as urea. Utilization of protein and formation of urea are under enzymatic regulation, suggesting genetic regulation. The present study examined the effect of sire line, sire, and sex on growth characteristics and plasma urea nitrogen (PUN) concentrations in the offspring of 11 Duroc sires and 11 Landrace sires bred to Yorkshire-Landrace dams. Plasma samples were obtained at approximately 107 (age class 107 d), 128 (age class 128 d), and 149 (age class 149 d), d of age from 511 boars, gilts, and barrows group-penned and fed standard finishing diets. Body weight and backfat (BF, mean of measurements at first rib, last rib, and last lumbar vertebra) were recorded at time of blood sample collection. Sire line, sex, age class, and age class x sex, influenced (P < 0.01) BW, BF, and PUN. Predicted traits; i.e., ADG, BW at 21 wk (BW21wk), average daily change in BF (ADCBF), BF at 21 wk (BF21wk), and mean of three PUN measures (mPUN) were generated. Mean (± SD) were: ADG, 888 ± 204 g; BW21wk, 94.2 ± 12.5 kg; ADCBF, 0.083 ± 0.052 mm; BF21wk, 13.8 ± 3.0 mm; and mPUN, 16.2 ± 4.4 mg/dL. These traits were influenced (P < 0.01) by sire within line and sex, and line influenced (P < 0.01) all traits. Heritability estimates were: ADG, 0.64; BW21wk, 0.47; ADCBF, 0.40; BF21wk, 0.57; and mPUN, 0.35. Phenotypic and genetic correlations of mPUN with other traits were low to moderate. Determination of PUN, as herein, may be with sufficient precision to allow its use in a selection protocol. Selection of pigs with superior growth performance and low PUN may result in greater efficiency of dietary nitrogen utilization and reduced negative environmental impact.