Previously, GH response to GHRH challenge at weaning has been shown to be indicative of ADG during a standard postweaning growth performance test in Angus cattle. In this study, we tested the hypothesis that GH response to GHRH before weaning would predict postweaning ADG. Bulls with the highest and lowest GH responses to GHRH over a 3-yr period, relative to their contemporaries, were used as s...

in order to study on the effect of incomplete sire's pedigree on the prediction of breeding value and estimation of genetic trend, two quantitative traits such as weaning weight and average daily gain with heritabilities 0.15 and 0.30 were simulated. phenotypic, genetic and environmental correlations were assumed 0.5. resulted data files with different proportion of missed sire pedigree (0...

Intensively reared piglets may face many early life challenges and these may affect behavior. The objective of this study was to examine the relationship between piglets' early life circumstances and their behavioral response in a backtest. Here, 992 piglets of 14 d of age were subjected to a backtest, in which they were restrained for 1 min in a supine position. The number of struggles in the ...

A 2-yr study was conducted during the 2004 to 2005 (YR1) and 2005 to 2006 (YR2) winter wheat grazing seasons to determine the effects of supplementation strategies and delivery methods on supplement intake and growth performance of grazing steers (YR1, n = 253, initial BW 255 +/- 25 kg; YR2, n = 116, initial BW 287 +/- 14 kg). The 5 treatments were as follows: 1) negative control (NC), no suppl...

The genetic parameters and (co) variance components of body weight at birth (BW), weaning (WW) and six months of age (BW6) and average daily gain (ADG) pre and post-weaning of Afshari sheep were estimated using restricted maximum likelihood (REML) methodology and animal model implemented in DFREML software. The likelihood ratio test (LRT) was used to compare the models. Year of birth, age of mo...

Organic acids have been supplemented to weanling pig diets in an attempt to improve postweaning lag. Organic acids have proved beneficial in improving average daily gain (ADG) and increasing nutrient digestibility (Falkowski and Aherne, 1984; Edmonds et al., 1985; Geisting and Easter, 1985). There has also been interest in acidifying grower pig diets in an attempt to increase ADG and improve fe...

The purpose of this study was to estimate components of variance and covariance for backfat and growth rate in swine tested in central test stations in the United States. Data were collected from 26 central boar test stations from 1984 through 1990. The traits analyzed were backfat adjusted to a 104.5-kg basis and ADG adjusted to a 36-kg on-test weight. Records from 7,951 purebred Yorkshire boa...

Interest in improving feed efficiency in cattle is intensifying. Residual feed intake (RFI), which is the difference between expected intake and that predicted based on energy demands, is now the most commonly used measure of feed efficiency over a given time period. However, RFI, as commonly defined, is independent of growth rate, which may affect its acceptance by industry. Residual BW gain (...