Genetic parameters for tick counts across months for different tick species and anatomical locations in South African Nguni cattle

Abstract

The objective of the study was to characterise genetic parameters across months for different tick species and anatomical locations in South African Nguni cattle. Tick counts were conducted monthly, over a 2-year period, on 586 Nguni cattle under natural infestation, from four herds located in different provinces of South Africa. The counts were recorded for six species of ticks (Amblyomma hebraeum, Rhipicephalus evertsi evertsi, Rhipicephalus decoleratus and microplus (Boofilids), Rhipicephalus appendiculatus, Rhipicephalus simus and Hyalomma marginatum) attached on eight anatomical locations on the animals and were summed by species and anatomical location. Heritability estimates, phenotypic and genetic correlations were estimated on a monthly basis using mixed linear models, fitting univariate and bivariate sire models. Fixed effects considered were location, sex, year and age as a covariate. Tick counts were higher in the hot months, and A. hebraeum was the most dominant tick species. Heritability estimates for tick count varied by month and trait and ranged from 0 to 0.89. Genetic correlations were mostly positive, and low to high, with some negative correlations with high standard error. Phenotypic correlations were low to moderate. In general, high genetic correlations were observed between whole body count and the anatomical location counts, suggesting that it may not be necessary to conduct whole body counts. Counts from the belly and perineum appeared to be the most suitable surrogate traits for whole body count. These findings provide useful information for developing strategies for the practical implementation of genetic selection, as a supplement to the traditional tick control measures.Electronic supplementary materialThe online version of this article (doi:10.1007/s11250-017-1336-2) contains supplementary material, which is available to authorized users.

Tick burden in Bos taurus cattle and its relationship with heat stress in three agroecological zones in the tropics of Colombia

“…The tick burden on the rump and tail of SM (7.2 ± 12.2), ROMO (5.8 ± 10.2) and CCC (9.4 ± 15.1) cattle was higher than the tick burden found on the rear legs, belly and flanks (1.0 ± 2.4, 4.6 ± 6.9 and 7.2 ± 11.1, respectively). These results agree with those obtained by [15] in Nguni cattle. These authors found that the tick burden on tail and perineum was higher than the tick burden on the belly throughout the year.…”

“…There is a scant amount of data in the literature on tick burden in cattle for tropical regions in the Americas. Most studies on this topic have been carried out in subtropical countries such as South Africa [8, 15], countries with extreme high temperatures such as Egypt [16] and Pakistan [17], and some tropical countries such as Tanzania [18] and Nigeria [21]. Tick burden is frequently reported using transformed data, which makes result comparison for actual tick burden difficult to interpret.…”

“…The distribution of these breeds is affected by the extremely diverse agroecological conditions found in Colombia. Several studies have shown that besides the climate and habitat type, other factors such as the breed, age and sex of the animals also have a significant effect on the tick burden in different cattle populations [8, 15–18]. In Colombia, the available literature on cattle ticks addresses the biological and ecological aspects of these parasites [4] and its geographical distribution [5].…”

Multiple Country and Breed Genomic Prediction of Tick Resistance in Beef Cattle

“…The Australian BR and TC scores and South African NG averaged counts had larger estimated values around 0.40 in our multi-trait analysis, and were are considerably higher than previous results obtained within-population under single trait analyses of 0.15 for BR (11). Nonetheless, a similarly high h 2 value of 0.42 was reported for another Tropical Composite Australian population, the Belmont Red (38) and depending on the time of the year h 2 for perineum tick counts ranged between 0.00 and 0.58 (39). The wide range of h 2 estimates for tick resistance in cattle found in the present and other studies is related to differences in phenotyping, environmental control and intrinsic population characteristics.…”

Tick Infestation and Piroplasm Infection in Barbarine and Queue Fine de l’Ouest Autochthonous Sheep Breeds in Tunisia, North Africa

“…Resistance to tick infestation was widely investigated in cattle [ 11 , 12 ] and experimental animals such as guinea-pigs [ 13 , 14 ]. In cattle, resistance to ticks was shown to be heritable [ 15 ], and in South African cattle, heritability for tick resistance assessed by tick counts was estimated between naught and 0.89 [ 16 ]. There are limited studies and reports on sheep.…”