[show abstract][hide abstract] ABSTRACT: We quantified the potential increase in accuracy of expected breeding value for weights of Nelore cattle, from birth to mature age, using multi-trait and random regression models on Legendre polynomials and B-spline functions. A total of 87,712 weight records from 8144 females were used, recorded every three months from birth to mature age from the Nelore Brazil Program. For random regression analyses, all female weight records from birth to eight years of age (data set I) were considered. From this general data set, a subset was created (data set II), which included only nine weight records: at birth, weaning, 365 and 550 days of age, and 2, 3, 4, 5, and 6 years of age. Data set II was analyzed using random regression and multi-trait models. The model of analysis included the contemporary group as fixed effects and age of dam as a linear and quadratic covariable. In the random regression analyses, average growth trends were modeled using a cubic regression on orthogonal polynomials of age. Residual variances were modeled by a step function with five classes. Legendre polynomials of fourth and sixth order were utilized to model the direct genetic and animal permanent environmental effects, respectively, while third-order Legendre polynomials were considered for maternal genetic and maternal permanent environmental effects. Quadratic polynomials were applied to model all random effects in random regression models on B-spline functions. Direct genetic and animal permanent environmental effects were modeled using three segments or five coefficients, and genetic maternal and maternal permanent environmental effects were modeled with one segment or three coefficients in the random regression models on B-spline functions. For both data sets (I and II), animals ranked differently according to expected breeding value obtained by random regression or multi-trait models. With random regression models, the highest gains in accuracy were obtained at ages with a low number of weight records. The results indicate that random regression models provide more accurate expected breeding values than the traditionally finite multi-trait models. Thus, higher genetic responses are expected for beef cattle growth traits by replacing a multi-trait model with random regression models for genetic evaluation. B-spline functions could be applied as an alternative to Legendre polynomials to model covariance functions for weights from birth to mature age.
[show abstract][hide abstract] ABSTRACT: The aim of the present study was to evaluate the genetic correlations among real-time ultrasound carcass, BW, and scrotal circumference (SC) traits in Nelore cattle. Carcass traits, measured by real-time ultrasound of the live animal, were recorded from 2002 to 2004 on 10 farms across 6 Brazilian states on 2,590 males and females ranging in age from 450 to 599 d. Ultrasound records of LM area (LMA) and backfat thickness (BF) were obtained from cross-sectional images between the 12th and 13th ribs, and rump fat thickness (RF) was measured between the hook and pin bones over the junction between gluteus medius and biceps femoris muscles. Also, BW (n = 22,778) and SC (n = 5,695) were recorded on animals born between 1998 and 2003. The BW traits were 120, 210, 365, 450, and 550-d standardized BW (W120, W210, W365, W450, and W550), plus BW (WS) and hip height (HH) on the ultrasound scanning date. The SC traits were 365-, 450-, and 550-d standardized SC (SC365, SC450, and SC550). For the BW and SC traits, the database used was from the Nelore Breeding Program-Nelore Brazil. The genetic parameters were estimated with multivariate animal models and REML. Estimated genetic correlations between LMA and other traits were 0.06 (BF), -0.04 (RF), 0.05 (HH), 0.58 (WS), 0.53 (W120), 0.62 (W210), 0.67 (W365), 0.64 (W450 and W550), 0.28 (SC365), 0.24 (SC450), and 0.00 (SC550). Estimated genetic correlations between BF and with other traits were 0.74 (RF), -0.32 (HH), 0.19 (WS), -0.03 (W120), -0.10 (W210), 0.04 (W365), 0.01 (W450), 0.06 (W550), 0.17 (SC365 and SC450), and -0.19 (SC550). Estimated genetic correlations between RF and other traits were -0.41 (HH), -0.09 (WS), -0.13 (W120), -0.09 (W210), -0.01 (W365), 0.02 (W450), 0.03 (W550), 0.05 (SC365), 0.11 (SC450), and -0.18 (SC550). These estimates indicate that selection for carcass traits measured by real-time ultrasound should not cause antagonism in the genetic improvement of SC and BW traits. Also, selection to increase HH might decrease subcutaneous fat as correlated response. Therefore, to obtain animals suited to specific tropical production systems, carcass, BW, and SC traits should be considered in selection programs.
Journal of Animal Science 10/2009; 88(1):52-8. · 2.09 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although growth hormone (GH) receptors (GHRs) in many species bind human (h) GH as well as their own GH, the hGHR only binds primate GH. Arg43 in hGHR interacts with Asp171 of hGH. Nonprimates have a His in the position equivalent to residue 171 of primate GH and a Leu in position 43 of primate GHR. To determine whether Arg43 accounts for the species specificity of the hGHR, point mutations that changed Leu43 to Arg were introduced into the cDNAs encoding the bovine (b) GHR or the rat GH binding protein (GHBP) and these mutants or their wild-type (WT) counterparts were expressed in mouse L cells. Binding of hGH or bGH to transfected cells or to GHBP secreted into the incubation medium was assessed by displacement of 125I-labeled hGH. WT and mutant bGHR bound hGH with similar affinity, but the affinity of the mutant receptors for bGH was reduced 200-fold. Likewise, WT and mutant GHBP bound hGH with equal affinity, but only WT GHBP bound bGH. Cross-linking of 125I-labeled hGH to WT or mutant GHR produced a 141-kDa labeled complex whose appearance was blocked by unlabeled hGH, but bGH blocked cross-linking only to WT receptors. Both hGH and bGH stimulated tyrosine phosphorylation of a 95-kDa protein in cells transfected with WT GHR, but bGH was less effective in cells expressing mutant GHR. We conclude that incompatibility of Arg43 in the hGHR with His171 in nonprimate GH is the major determinant of species specificity.
Proceedings of the National Academy of Sciences 03/1995; 92(4):959-63. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Growth hormone (GH) produces insulin-like effects in rat adipocytes that have been deprived of GH for at least 3 h. The effect of a saturating concentration of GH is qualitatively and quantitatively similar to that produced by 2-4 ng/ml insulin but differs from that of insulin in the respect that adipocytes become refractory to prolonged or repeated stimulation with GH. Since activation of tyrosine kinase is an early event in the action of both hormones, we investigated the possibility that GH stimulation of tyrosine phosphorylation of some protein in the insulin transduction cascade might result in the similar effect of the two hormones. Adipocytes were preincubated for 3 h in the absence of hormones and then reincubated without or with 500 ng/ml GH or 4-400 ng/ml insulin for 10 min. The cells were lysed with an equal volume of buffer containing 1% SDS and preheated to 100 degrees C. Proteins were separated by electrophoresis on 7.5% polyacrylamide gels and transferred to nitrocellulose membranes, and tyrosine-phosphorylated proteins were detected using anti-phosphotyrosine antiserum coupled to horseradish peroxidase and reagents to produce chemiluminescence. The faint band seen at 185 kDa in control lanes was increased by GH treatment in five independent experiments. Insulin produced a similar effect at a concentration of 4 ng/ml, and phosphorylation increased in a dose-related manner in cells treated with higher concentrations of insulin. A prominent approximately 95-kDa band that is probably not the beta subunit of the insulin receptor was also seen in GH-treated cells. The beta subunit of the insulin receptor has similar electrophoretic mobility to the 95-kDa protein, but was not phosphorylated to an extent that allowed detection when insulin was added at concentrations below 400 ng/ml. Phosphorylation of the 185- and 95-kDa bands was evident within 1 min after addition of GH, persisted for at least 30 min, and was equally prominent in sensitive and refractory cells. Antiserum to IRS-1 immunoprecipitated the tyrosine-phosphorylated 185-kDa protein. The data suggest that IRS-1 is a substrate for a GH-activated tyrosine kinase, possibly JAK-2, which may account for the insulin-like effects of GH. The data further suggest that refractoriness to insulin-like stimulation by GH may result from an additional GH-dependent action that is distinct from phosphorylation of IRS-1.
Journal of Biological Chemistry 01/1995; 269(48):30085-8. · 4.65 Impact Factor