Reproductive performance of cattle: a meta-analytical approach

This study aims to evaluate the relationship between the pregnancy rate of female beef cattle in southern Brazil and other factors such as age at mating, animal category, breed and type of pasture before mating. Data from 29 dissertations and theses were analyzed, representing 2862 bovine females ex...

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Bibliographic Details
Published inJournal of animal science Vol. 96; pp. 144 - 145
Main Authors Eloy, L, Pötter, L, Lobato, J, Bremm, C, Laca, E
Format Journal Article
LanguageEnglish
Published Champaign Oxford University Press 01.12.2018
Subjects
Age
Beef
Beef cattle
Bovidae
Cattle
Confidence intervals
Females
Genetic transformation
Heterogeneity
Mathematical analysis
Mating
Meta-analysis
Pasture
Pregnancy
Reproduction
Statistical analysis
Brazil
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Summary:This study aims to evaluate the relationship between the pregnancy rate of female beef cattle in southern Brazil and other factors such as age at mating, animal category, breed and type of pasture before mating. Data from 29 dissertations and theses were analyzed, representing 2862 bovine females exposed to reproduction in southern Brazil between 1976 and 2015. We used Freeman-Tukey double arcsine transformation method for meta-analysis of pooled proportion estimates, and 95% confidence intervals were calculated within a random effect model framework using the metaprop function of the R meta package to synthesize data, determine averages within groups, and evaluate within-group heterogeneity. The overall meta-analytical estimate of the pregnancy rate was 67.3%. I2 statistics indicated high heterogeneity for the estimates of the pregnancy rate between studies for overall analysis as well as for individual studies (I2=94.5, p<.0001), with a hight variability of the pregnancy rate, ranging from 8.8 to 96.9%. Because of these high I2 values, we performed several sub-groups analyses (by animal age, category, breed or type of pasture) to address this issue. The pregnancy rate is different when beef cattle females are mated at 14, 24 or 36 months of age. The highest pregnancy rate was observed when females were mated at 24 months of age. When females were mated at 24 months of age, an average pregnancy rate of 80.0% was observed, with a variation in the confidence interval from 40.4 to 96.9% with lower and higher values in the pregnancy rate, by Rosa, A.A.G. (2010) and Pötter, B.A.A. (2002), respectively. The database showed that the pregnancy rate is similar for heifers or primiparous cows, crossbred or Taurine cattle, and those maintained in winter or natural pasture.
ISSN:0021-8812
1525-3163