Tick-borne pathogens (TBP) are responsible for significant economic losses to cattle production, globally. This is particularly true in countries like India where TBP constrain rearing of high yielding Bos taurus, as they show susceptibility to acute tick borne disease (TBD), most notably tropical theileriosis caused by Theileria annulata. This has led to a programme of cross breeding Bos taurus (Holstein-Friesian or Jersey) with native Bos indicus (numerous) breeds to generate cattle that are more resistant to disease. However, the cost to fitness of subclinical carrier infection in crossbreeds relative to native breeds is unknown, but could represent a significant hidden economic cost. In this study, a total of 1052 bovine blood samples, together with associated data on host type, sex and body score, were collected from apparently healthy animals in four different agro-climatic zones of Maharashtra state. Samples were screened by PCR for detection of five major TBPs: T. annulata, T. orientalis, B. bigemina, B. bovis and Anaplasma spp.. The results demonstrated that single and co-infection with TBP are common, and although differences in pathogen spp. prevalence across the climatic zones were detected, simplistic regression models predicted that host type, sex and location are all likely to impact on prevalence of TBP. In order to remove issues with autocorrelation between variables, a subset of the dataset was modelled to assess any impact of TBP infection on body score of crossbreed versus native breed cattle (breed type). The model showed significant association between infection with TBP (particularly apicomplexan parasites) and poorer body condition for crossbreed animals. These findings indicate potential cost of TBP carrier infection on crossbreed productivity. Thus, there is a case for development of strategies for targeted breeding to combine productivity traits with disease resistance, or to prevent transmission of TBP in India for economic benefit.
Background: Benzimidazole resistance is one of the key problem in small ruminant production. A rapid, truthful and responsive system is required for detection benzimidazole resistance so that proper regulatory measure can be applied. Allele specific PCR is one of the tools to understand the mechanism and origin of benzimidazole resistance.
Methods: A total 198 larvae of Haemonchus contortus were isolated from goats of Chhattisgarh region, central India were genotyped by allele specific polymerase chain reaction (AS-PCR). Faecal samples of goats were collected from three Government farms and adjoining field goats and were subjected for faecal culture, separately. DNA of third stage larva was used for nested PCR for amplification of β- tubulin gene. Restriction Fragment Length Polymorphism (RFLP) was applied on nested PCR product for species identification with RsaI enzyme. AS-PCR was applied on the nested-PCR product to know the genotypic and allelic frequency.
Result: The nested PCR amplified product showed approximately 820 bp in all cases and PCR-RFLP revealed 462 bp, 211 bp and 147 bp fragments, which confirmed the species as H. Contortus. Frequency of resistant allele ('r') was 49.7% and 50.3% for susceptible allele ('S '). Frequency of homozygous resistant (rr), heterozygous susceptible (rS) and homozygous susceptible (SS) genotype were 33.83 per cent, 31.81 per cent and 34.34 per cent, respectively. The frequency of homozygous resistant (rr) genotype was low (19.61%) in field compare to farm (48.96%) indicating refugia in field region.
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