Klindt J, Thallman R M, Wise T
USDA-ARS, US Meat Animal Research Center, Clay Center, NE 68933, USA.
J Anim Sci. 2006 Jun;84(6):1323-30. doi: 10.2527/2006.8461323x.
In pork production, the efficiency of dietary protein (AA) use is low, resulting in urinary excretion of large quantities of nitrogen as urea. Use of AA and formation of urea are under enzymatic regulation, suggesting genetic regulation. The current study examined the effects 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 3 measurements) were recorded at the time of blood sample collection. Sex, age class, and their interaction influenced (P < 0.01) BW, BF, and PUN. Predicted traits (i.e., ADG, BW at 21 wk, average daily change in BF, BF at 21 wk, and the mean of 3 PUN measures) were generated. Means (+/-SD) were: ADG, 888 +/- 204 g; BW at 21 wk, 94.2 +/- 12.5 kg; average daily change in BF, 0.083 +/- 0.052 mm; BF at 21 wk, 13.8 +/- 3.0 mm; and the mean of 3 PUN measures, 16.2 +/- 4.4 mg/dL. Predicted weight traits were influenced (P < 0.05) by sire line, and sex influenced (P < 0.01) all predicted traits. Heritability estimates for PUN at 107, 128, and 149 d of age were 0.35 +/- 0.15, 0.21 +/- 0.13, and 0.16 +/- 0.12, respectively. Phenotypic correlations of PUN with growth and fat traits were low. Genetic correlations of PUN measured at 107 d with growth and fat traits were low. However, genetic correlations of PUN measured at 128 or 149 d with growth and fat traits ranged from 0.81 to 0.95. Determination of PUN, as herein, may be of sufficient precision to allow its use in a selection protocol. Selection of pigs with superior growth performance and low PUN may result in a greater efficiency of dietary nitrogen use and a reduced negative environmental impact.
在猪肉生产中，日粮蛋白质（氨基酸）的利用效率较低，导致大量氮以尿素形式随尿液排出。氨基酸的利用和尿素的形成受酶调控，这表明存在遗传调控。本研究考察了父系、父本以及性别对11头杜洛克公猪和11头长白公猪与约克夏-长白母猪杂交后代生长性能和血浆尿素氮（PUN）浓度的影响。在大约107日龄（年龄组=107天）、128日龄（年龄组=128天）和149日龄（年龄组=149天）时，从511头群养并饲喂标准育肥日粮的公猪、后备母猪和阉猪采集血浆样本。在采集血样时记录体重和背膘厚（BF，3次测量的平均值）。性别、年龄组及其交互作用对体重、背膘厚和PUN有影响（P<0.01）。生成了预测性状（即平均日增重、21周龄体重、背膘厚平均日变化、21周龄背膘厚以及3次PUN测量值的平均值）。平均值（±标准差）为：平均日增重888±204克；21周龄体重94.2±12.5千克；背膘厚平均日变化0.083±0.052毫米；21周龄背膘厚13.8±3.0毫米；3次PUN测量值的平均值16.2±4.4毫克/分升。预测体重性状受父系影响（P<0.05），性别对所有预测性状有影响（P<0.01）。107日龄、128日龄和149日龄时PUN的遗传力估计值分别为0.35±0.15、0.21±0.13和0.16±0.12。PUN与生长和脂肪性状的表型相关性较低。107日龄时测量的PUN与生长和脂肪性状的遗传相关性较低。然而，128日龄或149日龄时测量的PUN与生长和脂肪性状的遗传相关性在0.81至0.95之间。如本文所述，PUN的测定精度可能足以使其用于选择方案。选择生长性能优良且PUN较低的猪可能会提高日粮氮的利用效率，并减少对环境的负面影响。
