Reproductive success or failure in four breed groups of beef bulls

Sílvio Renato Oliveira Menegassi,Maitê De Moraes Vieira,João Batista Gonçalves Costa Junior,Fernanda Gomes Moojen,Vanessa Peripolli,Eduardo Antunes Dias,Júlio Otávio Jardim Barcellos

doi:10.1590/s1806-92902015000700002

Abstract

The objective of this study was to determine the main causes of failure in bull breeding using a soundness evaluation in Rio Grande do Sul State/Brazil. We evaluated 19,836 bulls from 15 different breeds with ages ranging from two to eight years. The failures of bulls in each step were analyzed by logistic regression. The binary logistic regression was applied because the response variable had only two responses: Success (1) and Failure (0). Older bulls are more likely to be rejected than are younger bulls, regardless of their genetic group. Depending on the step of the assessment, one or another group is rejected. All steps of bull breeding soundness evaluation (BBSE) are important, with special attention to the failures of the behavioral evaluation (libido and physical ability). A BBSE performed before the breeding season reduces the risk of sub-fertile bulls in the herd.

Highlights

More than 90% of cattle reproduction in Brazil is conducted by natural breeding
The objective of this study was to determine the main causes of failure in bull breeding using a soundness evaluation in Rio Grande do Sul State/Brazil
Older bulls are more likely to be rejected than are younger bulls, regardless of their genetic group

Summary

Introduction

More than 90% of cattle reproduction in Brazil is conducted by natural breeding. It is well-documented that bull selection affects the performance of the herd (Parkinson, 2004; Ellis et al, 2005); the use of reliable methods to evaluate the reproductive potential, such as the bull breeding soundness evaluation (BBSE), is critical in ranch management.The bull breeding soundness evaluation is seen as a quick, reliable and cost-effective method. More than 90% of cattle reproduction in Brazil is conducted by natural breeding. It is well-documented that bull selection affects the performance of the herd (Parkinson, 2004; Ellis et al, 2005); the use of reliable methods to evaluate the reproductive potential, such as the bull breeding soundness evaluation (BBSE), is critical in ranch management. The bull breeding soundness evaluation is seen as a quick, reliable and cost-effective method. A properly performed and interpreted evaluation provides a useful management tool to reduce the risk of sub-fertile bulls in the herd (McGowan et al, 2002). The yearly assessment of bull fertility potential remains a key management tool to achieve higher reproductive performance. Reproductive success will continue to depend mainly on the capacity to evaluate all available information coming from BBSE (Foote, 2003)

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Conclusion