This study was conducted to determine relative relationships among factors affecting dystocia in Brahman-cross heifers. Body and pelvic measurements were obtained in mid-June (when heifers were approximately 17 mo old), 45 d after a 60-d breeding season. Heifers studied were 207 Red Brangus, 209 Simbrah, and 250 Braford bred to Black Angus bulls; calving began on December 1. Heifers grazed stoc...

Birth weight (BWT) and calving difficulty (CD) were recorded on 4,580 first parity females from the Germplasm Evaluation (GPE) program at the U.S. Meat Animal Research Center. Both traits were analyzed using a bivariate animal model with direct and maternal effects. Genetic groups for breed of AI sire were fitted to estimate breed differences. Bos Indicus influenced breeds tended to have the la...

Calving difficulty was analyzed under threshold and linear models considering either a fixed or random herd-year effect. The aim of the study was to compare models for predicting breeding values according to the size of herd-year groups. When simulating data sets with small herds, in order to obtain an unbiased evaluation under a nonrandom and negative association of sire and herd effects, the ...

Data from pure breeds, as well as reciprocal crosses of German Angus (GA) and Simmental (SIM) beef cattle, were used to estimate genetic parameters and to evaluate the suitability for crossbreeding in terms of increasing productivity. Traits of interest were calving difficulty, birth weight (BWT), weaning weight (WWT), and ADG from birth to weaning. Data were collected over a period of 7 yr fro...

Data on 186 Hereford heifers from five South Dakota ranches were collected to evaluate the relationships of pelvic structure and body measurements with calving difficulty (CD) and pelvic area. Body measurements obtained prebreeding and precalving included two internal pelvic and seven external rump measurements, three pelvic angles and two slope of rump measurements. A calving difficulty score ...

The objectives of this work were to compare reproduction and parturition traits of the Criollo breed Romosinuano as straightbred and crossbred cows with Angus and Brahman, to estimate heterosis and direct and maternal genetic breed effects, and to describe calf loss, cow removals from the project, the occurrence of calving difficulty, inadequate calf vigor at birth, and udder problems by cow br...

Calving difficuity at first and second parturition, using data recorded on 476 purebred Charolais heifers from a ranch in Southeastern Arizona, were analyzed by analysis of variance, step-wise multiple regression and discriminant analysis. Dystocia score (1 = no assistance through 4 = extreme difficulty) was the dependent variable with dam and calf effects independent variables. In this herd, 3...

Data on Angus (ANG), Charolais (CHR), Hereford (HER) and Limousin (LIM) cattle were used to estimate genetic parameters for calving difficulty (CD) and to quantify genetic relationships among CD, birth weight (BWT) and gestation length (GL). Bayesian analysis was carried out using Gibbs sampling to obtain means of marginal posterior distributions. Estimated heritabilities for direct genetic eff...

The objective of this research was to determine the prevalence, risk factors and consequent effect of dystocia on lactation performance in Holstein dairy cows in Iran. The data set consisted of 55,577 calving records on 30,879 Holstein cows in 30 dairy herds for the period March 2000 to April 2009. Factors affecting dystocia were analyzed using multivariable logistic regression models through t...