Haematological Profiles and Serum Ige levels AS Tick Resistance Phenotypes upon Tick Infestation in Indicine and Taureen Cattle Breeds
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Date
2023-11-15
Authors
Ngetich, Collins
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Publisher
Kenyatta University
Abstract
ABSTRACT
Globally, a population of over 80% of cattle are at risk of tick and tick-borne diseases (TTBDs). In tropical Africa co-infestation with multiple tick species is common leading to mixed infections with tick-borne pathogens and severe clinical outcomes of individual animals and herds. The economic losses from animal mortality and the cost of acaricides and therapeutics demands the incorporation of alternative disease control strategies including the use of tick- resistant cattle breeds. The gold standard method for phenotyping tick resistance in cattle is by counting ticks on the body (partial or whole body). However, tick counting is tedious, require experienced workers and is expensive. Therefore, there is need for alternative methods for phenotyping tick resistance more easily, cheaply, fast and on a large scale. The current study assessed the Immunoglobulin E (IgE) response and haematological cellular profiles as potential phenotypes for tick resistance in Bos indicus (Zebu) and Bos taurus (Friesian and Ayrshire) cattle breeds under experimental infestation with Rhipicephalus decoloratus larvae. Fifty-four taurine and 52 indicine calves were each infested with ~2500 larvae. Replete adult female ticks were counted daily from day 21 to 25 on each animal. Sera blood and whole blood samples were obtained from each animal on day 0 and 23. Serum IgE levels (by ELISA) and total blood counts were measured before and after infestation with pre-infestation IgE levels as baseline. Mean tick count on the two breeds were compared using a paired student t-test. Statistical analysis of the haematological cellular counts, before and after infestation, was tested using a one-way analysis of variance (ANOVA) and adjusted with a Tukey post hoc test. Pearson correlation test was used to analyse the relationship between the tick count to haematological cellular count and IgE titers. P≤0.05 was considered statistically significant. The results of tick counts between the two cattle breeds were statistically different (overall mean of 157.3725 ticks on indicine breed and 528.6735 ticks on taurine breed per animal (t=5.424, df=102) (P< 0.0001)). The frequency distribution of tick counts in indicine group showed 91% of the cattle were resistant and 9% moderately resistant, while the taurine breeds, 86% were susceptible whereas 13% were refractory, following artificial application of R. decoloratus. In the parasitized taurine calves, there was significant decrease in white blood cells (P= 0.0045), red blood cells (P=0.0156), haematocrit (P=0.0207), granulocytes (P=0.0139) and lymphocytes (P= 0.0104). The parasitized indicine calves had a significant difference in the mean differential cell count of white blood cells only (P= 0.0012). There was positive correlation between tick count and IgE concentration in taurine breed (P< 0.05). Red blood cells count (and haemoglobin and haematocrit), lymphocytes and IgE profiles. These results underpin the need to deepen the search for a suitable phenotype for cattle host resistance to ticks.
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Abstract