Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/24/2004
Publication Date: 7/26/2004
Citation: Klindt, J.M. 2004. Relationships among measures of growth performance and plasma urea nitrogen (PUN) in barrows [abstract]. Journal of Animal Science 82(Suppl. 1):4.
Technical Abstract: Our previous work [J. Anim. Sci. 81(Suppl. 2):36, 2003] showed that plasma concentrations of PUN are genetically regulated and moderately heritable, 0.35. Objective of the present study was to exam the relationships among measures of growth and PUN in grower/finisher pigs. Barrows, n=96, BW=29.3±0.5 kg, 3 to 4 per litter, 27 litters, were assigned at 69±0.5 d of age. Pigs were placed in individual pens and fed standard grower/finisher diets until slaughter at 118 kg BW. At slaughter, chilled carcass wt (Cldwt) and wt of trimmed lean cuts (Tlncut) were recorded. At 2-wk intervals during the trial BW, average of ultrasonic backfat at three sites, and feed consumption were recorded. At each weighing a blood sample was collected for determination of plasma urea nitrogen (PUN). Within pig PUN was averaged to obtain mPUN. Two pigs were removed before the end of the trial. Data recorded at the end of the trial was adjusted to average slaughter wt, 117.2±0.3 kg. Daily change in average of three backfat measures (ADCBF), ADG, days to slaughter (Tday), final average backfat thickness (FnBF), Cldwt, Tlncut, and mPUN were affected (P<0.05) by litter. Litter affected (P<0.08) total feed consumed (Tfeed). Feed/d and efficiency of BW gain (Eff) were not affected by litter (P=0.14). For the subsequent examination of the relationship of mPUN with growth measures, pigs were classified as loPUN (n=31; mPUN, 26.1 to 36.1, mean=32.1 mg/dL), medPUN (n=32; mPUN, 36.4 to 42.1, mean=39.2 mg/dL), and hiPUN (n=31; mPUN, 42.4 to 91.3, mean=54.3 mg/dL). PUN group influenced (P<0.05) feed/d, ADCBF, FnBF, and Tlncut. hiPun barrows had higher feed/d, ADCBF, and FnBF and reduced Tlnct. Effect of PUN group on feed/d, was nonlinear. Results concur with the reported low phenotypic and genetic correlations among PUN and growth measures [Klindt, et al., J. Anim. Sci. 81(Suppl. 2):36, 2003]. These results suggest that selection against PUN may be accomplished without significant sacrifices in growth performance.