Results of 23 years of selection for post-weaning weight in a Caracu beef herd

Data from 1 698 animals belonging to an experimental Caracu herd were analysed with the objective of calculating the population selection differentials, generation intervals, effective size and inbreeding coefficients, and to estimate the direct and correlated responses for growth traits after 23 years of selection for post-weaning weight. The following traits were analysed: birth weight (BW), weaning weight corrected to 210 days of age (W210), weight corrected to 378 days for the males (W378), weight corrected to 550 days for the females (W550) and hip height for the males (HGTm) at the end of a feedlot test, and for the females (HGTf) at 550 days of age. The sire (W378) and dam (W550) weighted selection differentials for post-weaning weight were 1.10 and 0.28 standard deviation units and generation intervals 5.2 and 6.2 years, respectively. Mean inbreeding coefficient increased in the last five years, from 0.49 to 1.95%. The heritability estimates were 0.38, 0.27, 0.36, 0.37, 0.35 and 0.41 for BW, W210, W378, W550, HGTm and HGTf, respectively. The annual genetic trend estimates were 0.98 ± 0.17 kg/year for W378 and 0.27 ± 0.15 kg/year for W550. The estimates for the correlated responses to selection were 0.08 ± 0.02 kg/year for BW, 0.48 ± 0.11 kg/year for W210, 0.06 ± 0.02 cm/year for HGTm and 0.02 ± 0.02 cm/year for HGTf. These results confirmed that direct selection for post-weaning weight based on individual performance was relatively effective in achieving progress in all the growth traits. Keywords: Beef cattle, Creole bovine, experimental herd, genetic trend, tropical adapted breed South African Journal of Animal Science Vol. 38 (2) 2008: pp. 136-14

Bayesian inference on field data for genetic parameters for some reproductive and related traits of Nellore cattle (Bos indicus)

We used Gibbs sampling in single and two-trait animal models to estimate genetic parameters for some reproductive and related traits of Nellore cattle (Bos indicus). Female traits were age at first calving (AFC), cumulative productivity (CP) and adult weight (AW). For males, scrotal circumferences at 365 and 450 days of age were analyzed. Gibbs sampling using the ‘Multiple Trait using Gibbs Sampling under Animal Model’ (MTGSAM) program of Van Tassel and Van Vleck was used to estimate the (co)variance components of the traits and conduct genetic analyses. Heritabilities were AFC = 0.26, AW = 0.36 and CP = 0.25 under the single-trait animal model. The mean, mode and median estimates for genetic parameters obtained from the marginal posterior distributions were similar for all traits except AW, which presented lower values for the mode than the mean and median. However, the marginal posterior distributions for the traits studied presented a tendency toward normality. Favorable, but low, negative genetic correlations were found between male scrotal circumference and female age at first calving. The reproductive traits showed medium-magnitude heritabilities, which indicates that these traits should respond to selection and therefore should be included in genetic improvement programs

Measurement of charged particle spectra in minimum-bias events from proton-proton collisions at root s =13 TeV

Pseudorapidity, transverse momentum, and multiplicity distributions are measured in the pseudorapidity range vertical bar eta vertical bar 0.5 GeV in proton-proton collisions at a center-of-mass energy of root s = 13 TeV. Measurements are presented in three different event categories. The most inclusive of the categories corresponds to an inelastic pp data set, while the other two categories are exclusive subsets of the inelastic sample that are either enhanced or depleted in single diffractive dissociation events. The measurements are compared to predictions from Monte Carlo event generators used to describe high-energy hadronic interactions in collider and cosmic-ray physics.Peer reviewe