Genetic parameters of infectious bovine keratoconjunctivitis and its relationship with weight and parasite infestations in Australian tropical Bos taurus cattle

Abdirahman A Ali,Peter C Thomson,Haja N Kadarmideen,Christopher J O’Neill

doi:10.1186/1297-9686-44-22

Abstract

BackgroundInfectious bovine keratoconjunctivitis (IBK) or ‘pinkeye’ is an economically important ocular disease that significantly impacts animal performance. Genetic parameters for IBK infection and its genetic and phenotypic correlations with cattle tick counts, number of helminth (unspecified species) eggs per gram of faeces and growth traits in Australian tropically adapted Bos taurus cattle were estimated.MethodsAnimals were clinically examined for the presence of IBK infection before and after weaning when the calves were 3 to 6 months and 15 to 18 months old, respectively and were also recorded for tick counts, helminth eggs counts as an indicator of intestinal parasites and live weights at several ages including 18 months.ResultsNegative genetic correlations were estimated between IBK incidence and weight traits for animals in pre-weaning and post-weaning datasets. Genetic correlations among weight measurements were positive, with moderate to high values. Genetic correlations of IBK incidence with tick counts were positive for the pre-weaning and negative for the post-weaning datasets but negative with helminth eggs counts for the pre-weaning dataset and slightly positive for the post-weaning dataset. Genetic correlations between tick and helminth eggs counts were moderate and positive for both datasets. Phenotypic correlations of IBK incidence with helminth eggs per gram of faeces were moderate and positive for both datasets, but were close to zero for both datasets with tick counts.ConclusionsOur results suggest that genetic selection against IBK incidence in tropical cattle is feasible and that calves genetically prone to acquire IBK infection could also be genetically prone to have a slower growth. The positive genetic correlations among weight traits and between tick and helminth eggs counts suggest that they are controlled by common genes (with pleiotropic effects). Genetic correlations between IBK incidence and tick and helminth egg counts were moderate and opposite between pre-weaning and post-weaning datasets, suggesting that the environmental and (or) maternal effects differ between these two growth phases. This preliminary study provides estimated genetic parameters for IBK incidence, which could be used to design selection and breeding programs for tropical adaptation in beef cattle.

Highlights

Infectious bovine keratoconjunctivitis (IBK) or ‘pinkeye’ is an economically important ocular disease that significantly impacts animal performance
Since the 1950’s, one of the most important animal breeding experiments in Australia has been the development of a cross between Hereford and Shorthorn cattle, which is commercialised under the name ‘Adaptaur’; bulls from the HS line were released to the beef industry to provide genetic material
There is a lack of information on the genetic and phenotypic parameters for infectious bovine keratoconjunctivitis (IBK) in tropical cattle composites

Summary

Introduction

Infectious bovine keratoconjunctivitis (IBK) or ‘pinkeye’ is an economically important ocular disease that significantly impacts animal performance. Genetic parameters for IBK infection and its genetic and phenotypic correlations with cattle tick counts, number of helminth (unspecified species) eggs per gram of faeces and growth traits in Australian tropically adapted Bos taurus cattle were estimated. IBK, commonly known as ‘pinkeye’, is an inflammatory bacterial infection that affects the eyes of cattle. In the 1980’s, an Australian postal survey recorded that 81% of cattle owners reported the occurrence of IBK in their herds and 75% observed a reduction in weight gain of the affected cattle [9] This survey is outdated, IBK remains a serious problem for livestock industries, with an estimated annual incidence of 10% that costs over $AU 23 million in cattle production losses and management [10]. Treatment or vaccination may provide a short-term solution, genetic selection is an alternative long-term solution to control IBK incidence in cattle

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