|Yen, Jong Tseng|
Submitted to: Journal of Animal Science Supplement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2002
Publication Date: March 1, 2003
Citation: KLINDT, J.M., THALLMAN, R.M., YEN, J., WISE, T.H. EFFECTS OF SIRE LINE, SIRE, AND SEX ON PLASMA UREA NITROGEN (PUN), BODY WEIGHT, AND BACKFAT THICKNESS IN OFFSPRING OF DUROC AND LANDRACE BOARS AND HERITABILITIES. JOURNAL OF ANIMAL SCIENCE. 2003. v. 81(Suppl.2): Abstract p. 36. Technical Abstract: In pork production, efficiency of dietary protein (nitrogen) utilization is low, <50%, resulting in urinary excretion of large quantities of nitrogen as urea. Dietary protein accounts for 20 to 25% of the cost of diets and efficiency of its use affects economic efficiency. Utilization of protein and formation of urea are under enzymatic regulation, suggesting genetic regulation. The present study examines the effect of sire line, sire, and sex on growth characteristics and PUN concentrations in the offspring of 11 Duroc sires and 11 Landrace sires bred to Yorkshire-Landrace dams. Plasma samples were obtained at ~107, ~128, and ~149 d of age from 511 boars, gilts, and barrows group-penned and fed a standard finishing diet. Body weight (kg) and backfat (BF, mm, mean of measurements at 1st rib, last rib and last lumbar vertebra) were recorded at time of blood sample collection. Sire line, sire, sex, age, age*sex, and age*line*sire influenced (P < 0.01) BW, BF, and PUN. Single observation traits; i.e., ADG (kg/d), BW at 21wk (BW21wk, kg), avg. daily change in BF (ADCBF, mm/d), BF at 21wk (BW21wk, mm), and mean of three PUN measures (mPUN, mg/dL) were generated. All traits were influenced (P < 0.01) by sire and sex, and line influenced (P < 0.01) all traits except ADCBF (P > 0.65). Phenotypic correlations of mPUN with growth traits are: ADG, 0.05; BW21wk, 0.21; ADCBF, 0.23; and BF21wk, 0.42. Genetic correlations of mPUN with growth traits are: ADG, 0.12; BW21wk, 0.44; ADCBF, 0.22; and BF21wk, 0.62. Heritabilities (h2) are: ADG, 0.64; BW21wk, 0.47; ADCBF, 0.40; BF21wk, 0.57; and mPUN, 0.35. 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.