The influence of cattle breed on susceptibility to bovine tuberculosis in Ethiopia

Animal Health and Veterinary Laboratories Agency, TB Research Group, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom.
Comparative immunology, microbiology and infectious diseases (Impact Factor: 2.02). 02/2012; 35(3):227-32. DOI: 10.1016/j.cimid.2012.01.003
Source: PubMed


Bovine tuberculosis in domestic livestock such as cattle is an economically important disease with zoonotic potential, particularly in countries with emerging economies. We discuss the findings of recent epidemiological and immunological studies conducted in Ethiopia on host susceptibility differences between native zebu and the exotic Holstein-Friesian cattle that are increasingly part of the Ethiopian National herd, due to the drive to increase milk yields. These findings support the hypothesis that native Zebu cattle are more resistant to bovine tuberculosis. We also summarise the results of experimental infections that support the epidemiological data, and of laboratory experiments that suggest a role for the innate immune response, and in particular interleukin-6, in the outcome of bovine tuberculosis infection.

Download full-text


Available from: Abraham Aseffa, Jan 13, 2014
  • Source
    • "The indigenous cattle and the prevailing extensive rural production systems are unlikely to be able to satisfy the rise in this demand for livestock food products. Therefore, intensification of animal husbandry in developing countries has been sought (Vordermeier et al., 2012). Numerous key factors, combining biological, industrial and political aspects, were involved in these trends, having affected the current genetic status of indigenous cattle breeds, imposing risk on its diversity. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Generally taken, breeds of Bostaurus ancestry are considered more productive, in comparison with Bosindicus derived breeds that present enhanced hardiness and disease resistance, low nutritional requirements and higher capability of feed utilization. While breeds of B. taurus have been mostly selected for intensive production systems, indigenous cattle, developed mostly from indicine and African taurines, flourish in extensive habitats. Worldwide demographic and economic processes face animal production with new challenges - the increasing demand for animal food products. Intensification of animal husbandry is thus a desired goal in stricken parts of the world. An introduction of productive traits to indigenous breeds might serve to generate improved biological and economic efficiencies. For this to succeed, the genetic merit of traits like efficiency of feed utilization and product quality should be revealed, encouraging the conservation initiatives of indigenous cattle populations, many of which are already extinct and endangered. Moreover, to overcome potential genetic homogeneity, controlled breeding practices should be undertaken. The Baladi cattle are a native local breed found throughout the Mediterranean basin. Purebred Baladi animals are rapidly vanishing, as more European breeds are being introduced or used for backcrosses leading to improved production. The superiority of Baladi over large-framed cattle, in feedlot and on Mediterranean pasture, with respect to adaptability and efficiency, is highlighted in the current review. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · May 2015 · Meat Science
  • Source
    • "On the other hand, the introgressed animals descend, in part, from European cattle, which have not had the same history of selective pressures. It has been found that European breeds are more susceptible than local breeds to some infectious diseases that are prevalent in Africa, such as East Coast Fever [31,32], bovine tuberculosis [33,34], and trypanosomiasis [35,36]. Thus, the European breeds are, in this important respect, less well adapted to the East African environment, and introgressed animals, while more heterozygous due to outbreeding, are also less locally adapted. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Positive multi-locus heterozygosity-fitness correlations have been observed in a number of natural populations. They have been explained by the correlation between heterozygosity and inbreeding, and the negative effect of inbreeding on fitness (inbreeding depression). Exotic introgression in a locally adapted population has also been found to reduce fitness (outbreeding depression) through the breaking-up of co-adapted genes, or the introduction of non-locally adapted gene variants.In this study we examined the inter-relationships between genome-wide heterozygosity, introgression, and death or illness as a result of infectious disease in a sample of calves from an indigenous population of East African Shorthorn Zebu (crossbred Bos taurus x Bos indicus) in western Kenya. These calves were observed from birth to one year of age as part of the Infectious Disease in East African Livestock (IDEAL) project. Some of the calves were found to be genetic hybrids, resulting from the recent introgression of European cattle breed(s) into the indigenous population. European cattle are known to be less well adapted to the infectious diseases present in East Africa. If death and illness as a result of infectious disease have a genetic basis within the population, we would expect both a negative association of these outcomes with introgression and a positive association with heterozygosity. In this indigenous livestock population we observed negative associations between heterozygosity and both death and illness as a result of infectious disease and a positive association between European taurine introgression and episodes of clinical illness. We observe the effects of both inbreeding and outbreeding depression in the East African Shorthorn Zebu, and therefore find evidence of a genetic component to vulnerability to infectious disease. These results indicate that the significant burden of infectious disease in this population could, in principle, be reduced by altered breeding practices.
    Full-text · Article · Nov 2013 · BMC Evolutionary Biology
  • Source
    • "Besides differences in husbandry, the observed variation in lesion distribution may also indicate genetic differences in TB susceptibility among breeds. European Bos taurus cattle breeds in Ethiopia have been shown to be more susceptible than native Bos indicus cattle [61]. There is also evidence of heritable variation in TB susceptibility within breeds in Irish cattle [62] and so our findings are consistent with the view that host genetic variation influences the outcome of exposure to M. bovis and that knowledge of this variation may have a role in future disease control programmes [63]–[65]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Strains of many infectious agents differ in fundamental epidemiological parameters including transmissibility, virulence and pathology. We investigated whether genotypes of Mycobacterium bovis (the causative agent of bovine tuberculosis, bTB) differ significantly in transmissibility and virulence, combining data from a nine-year survey of the genetic structure of the M. bovis population in Northern Ireland with detailed records of the cattle population during the same period. We used the size of herd breakdowns as a proxy measure of transmissibility and the proportion of skin test positive animals (reactors) that were visibly lesioned as a measure of virulence. Average breakdown size increased with herd size and varied depending on the manner of detection (routine herd testing or tracing of infectious contacts) but we found no significant variation among M. bovis genotypes in breakdown size once these factors had been accounted for. However breakdowns due to some genotypes had a greater proportion of lesioned reactors than others, indicating that there may be variation in virulence among genotypes. These findings indicate that the current bTB control programme may be detecting infected herds sufficiently quickly so that differences in virulence are not manifested in terms of outbreak sizes. We also investigated whether pathology of infected cattle varied according to M. bovis genotype, analysing the distribution of lesions recorded at post mortem inspection. We concentrated on the proportion of cases lesioned in the lower respiratory tract, which can indicate the relative importance of the respiratory and alimentary routes of infection. The distribution of lesions varied among genotypes and with cattle age and there were also subtle differences among breeds. Age and breed differences may be related to differences in susceptibility and husbandry, but reasons for variation in lesion distribution among genotypes require further investigation.
    Full-text · Article · Sep 2013 · PLoS ONE
Show more