Publications by authors named "O Ravagnolo"
Selection for feed efficiency is the goal for many genetic breeding programs in beef cattle. Residual feed intake has been included in genetic evaluations to reduce feed intake without compromising performance traits as liveweight, body gain or carcass traits. However, measuring feed intake is expensive, and only a small percentage of selection candidates are phenotyped.
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- Crossbreeding can enhance reproductive traits in cattle herds through advantages like breed differences, heterosis, and breed complementarity.
- The study analyzed reproductive data from 1,164 females across various genetic groups of Hereford, Angus, Nellore, and Salers under grazing conditions, focusing on traits like artificial insemination probability, calving success, and days to calving.
- Results showed that F1 crossbred females had better artificial insemination rates compared to purebreds, particularly crossbred A/H heifers and N/H cows, with dominance effects boosting the performance of heifers in terms of artificial insemination and calving success.
Article Synopsis
- Model-based accuracy in genetic evaluations is influenced by prediction error variance (PEV) and inbreeding coefficient (F), but ignoring inbreeding can lead to significant errors.
- Ignoring inbreeding in reliability calculations and in the pedigree relationship matrix A results in skewed estimates, especially in rabbits, where inbreeding increases substantially over generations.
- The study emphasizes the necessity of incorporating inbreeding in both settings to improve the accuracy of BLUP and SSGBLUP evaluations for various animal populations.
Description of the growth curve for Angus pasture-fed cows under extensive systems.
J Anim Sci
September 2015
Growth curves are useful for describing the sigmoid shape of an animal's weight pattern over time. The purpose of the present study was to describe, for the first time, a complete growth curve for pasture-fed Angus cows in Uruguay and to analyze the major fixed effects that affect the estimation of mature cow weight (CW). A total of 22,743 records from 5,284 cows belonging to 73 herds were used in the statistical analysis.
View Article and Find Full Text PDFEffect of heat stress on nonreturn rate in Holsteins: fixed-model analyses.
J Dairy Sci
November 2002
The objective of this study was to examine the relationship between reproductive traits and heat stress. Nonreturn rate at 45 d (NR45) was analyzed in a fixed-effect model that included the temperature-humidity index (THI) from a nearby weather station as a measurement of heat stress. Data consisted of 150,200 first inseminations at first and later parities of 110,860 Holstein cows from 550 herds in Georgia, Tennessee, and Florida with weather information from 16 weather stations.
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