Likewise, there was a higher prevalence of tick infestation in females On the other hand, no significant differences were found for the infestation prevalence of R. In the experimental stations where the cattle for our study were kept, bulls received preferential management since they had resting periods before the start of the next breeding season, and were allocated in paddocks with a lower stocking rate.
Conversely, cows were always kept at higher stocking rates. These particular conditions received by bulls during some months of the year might explain why we found a lower tick burden in males compared to females in our study.
We found a significant correlation between age and tick burden in the Colombian breeds evaluated. Several studies have found a significant effect of the age of cattle on tick burden [ 8 , 16 , 17 , 21 ]. Rehman et al. Most studies on tick burden in cattle have not evaluated the effect of live weight. Our study showed that in addition to age, live weight also had a significant effect on tick burden: the heavier the animal the higher the tick burden. This agrees with studies where the age had a significant correlation with tick burden in cattle [ 8 , 16 , 17 , 21 ] since age and live weight are highly correlated.
It is possible to hypothesize that factors contributing to the higher tick burden in heavier animals could be either a compromised immune system in heavier older animals as they tend to get weaker with age or that larger animals have a wider skin surface with a denser vasculature. The significant effect of breed in our study on tick burden has also been reported in other studies. In South Africa, Marufu et al. In the latter study, a higher tick infestation rate was found in Friesian cattle Similarly, in Pakistani cattle, Rehman et al.
Asmaa et al. However, in our study, we did not have tick burden data from other exotic breeds to make these comparisons. Therefore, further research would be required in order to compare the tick burden between Colombian Bos taurus cattle breeds and Bos indicus breeds, which are widely used on beef cattle farms in the region. The different environmental conditions found on the experimental stations, where the four Colombian cattle breeds were kept, might have influenced the tick burden on these animals.
However, the ROMO and CCC breeds were located in the same experimental station, and they grazed on the same type of grass and received the same herd management. In this case, where we had a greater control of the environment variation, the significant differences found between the two breeds could be attributed to a genetic effect. Moreover, the significant effect of family nested in breed also suggests a possible genetic influence on the individual response to tick attachment. A genetic effect causing the difference in tick burden between ROMO and CCC breeds might be expressed by a particular phenotype such as coat color or hair length.
Moreover, the hair length and the level of smoothness of the coat smooth vs woolly had a significant effect on tick burden in South African cattle [ 8 , 24 ], while skin thickness significantly affected the tick burden in Brazilian crossbred cattle during dry and rainy seasons [ 25 ]. Gene expression studies showed that both immune and non-immune mechanisms are associated with tick resistance in cattle [ 26 ]. Differences in tick burden found between ROMO and CCC cattle are less likely to be due to a different coat color or smoothness as these breeds share great similarity in function of these traits.
Instead, skin thickness, hair density or the particular immunological response to tick infestation of each breed, might be hypothesized as characteristics with a significant genetic-related effect on the tick burden for these breeds.
Environmental changes have a positive or negative effect on the physiological heat regulation mechanisms of cattle and potentially on the tick burden of these animals [ 8 ]. However, the ability of cattle to dissipate heat load by sweating and panting is compromised in hot and humid conditions making cattle experience heat stress much faster than other livestock species such as swine [ 9 ]. Therefore, the aforementioned adaptation-related traits would be particularly important for cattle located in the tropics, since humidity levels are higher in this region throughout the whole year compared with other latitudes.
The tick burden in cattle might be affected by the same traits that have an influence on the thermal comfort of animals. For instance, cattle with longer hair or a woolly coat would struggle to dissipate heat, but at the same time, this phenotype would make the attachment of ticks easier to the body. In the case of coat color, some studies found higher tick burdens in cattle with a dark coat compared with those that had lighter coat colors [ 23 , 25 ], which might be due to the higher heat absorbance by darker coats, making the skin warmer and more attractive for parasites.
On the other hand, traits such as skin thickness, hair density and skin secretions could have a role for tick resistance in domestic livestock [ 27 ]. These latter traits might also have an influence on the cattle thermal comfort since they affect the ability of the animal to dissipate heat. Further studies on ticks in Colombian cattle breeds should include variables such as hair length, coat color and skin characteristics in order to analyze its influence on tick infestation levels and determine possible significant differences for these traits among breeds.
The relationship observed between THI and tick burden indicates that high THI values would be associated with a lower tick burden on the breeds considered in our study. On the other hand, and according to the results on AI described in our study, a higher tick infestation would be expected when animals experience a higher thermal discomfort.
However, THI does not account for variables taken directly from cattle but instead this index measures the level of thermal stress by accounting for the effects of air temperature and humidity in the environment [ 9 ]. The tick burden on cattle is related with the survival of these parasites in the environment.
In Australia, Sutherst et al. Likewise, the authors also found a reduced tick egg survival with a soil temperature greater than It is possible that under tropical conditions, the viability of tick eggs or the survival of the tick itself is compromised when temperatures reach a certain threshold. Furthermore, high environmental temperatures can affect the hair growth in cattle so that shorter and fewer hairs on the body would allow animals to lose more heat from sweating and evaporation when temperatures are elevated [ 8 ], and at the same time, it would discourage tick attachment to the skin.
Results from our study suggest that the THI threshold at which the tick burden on cattle is affected would differ depending on the breed. On the other hand, the two breeds studied in the Caribbean region showed different THI thresholds.
The present study also showed a significant correlation between both breed and family with the tick burden of Colombian cattle breeds. This could have potential implications for selection and mating decisions within breeding programs to obtain future generations of pure or crossbred cattle with higher tick resistance. On the other hand, the significant correlation of both age and sex with tick burden is key information that might be eventually used to improve herding strategies and to develop new tick control methods.
The association between heat stress and tick burden on cattle would suggest that the implementation of grazing and management strategies to minimize heat stress might be used as a method to reduce the tick burden in cattle herds. There was a significant association of breed, sex, age and live weight on the tick burden of Bos taurus Colombian cattle breeds. The particular environmental conditions of each agroecosystem might have affected the differences observed in the distribution of ticks on the body of cattle.
A higher thermal discomfort is associated with a higher tick burden in cattle that possibly have a lower level of adaptability, and this relationship would be directly affected by some of the traits that have an influence on the thermal comfort of the animal. A decrease of the tick burden in cattle could be associated with higher heat stress levels in a tropical environment.
However, this interaction between tick burden and environmental heat stress might be affected by characteristics of the agroecological region itself, the breed, the genetic resistance of the individual tick and the thermal adaptability of cattle. Principles of Veterinary Parasitology. Chichester, UK: Wiley Blackwell; Veterinary Parasitology. An estimate of the economic effects of cattle tick Boophilus microplus infestation on Queensland dairy farms.
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Growth performance of Blanco Orejinegro and Romosinuano bullocks on pasture. Rev Col Cienc Pec. Effect of polymorphisms in the Slc11a1 coding region on resistance to brucellosis by macrophages in vitro and after challenge in two Bos breeds Blanco Orejinegro and Zebu.
Genet Mol Biol. Genetic parameters for tick counts across months for different tick species and anatomical locations in South African Nguni cattle. Trop Anim Health Prod. Studies on prevalence, risk indicators and control options for tick infestation in ruminants. Distribution of ticks infesting ruminants and risk factors associated with high tick prevalence in livestock farms in the semi-arid and arid agro-ecological zones of Pakistan.
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Facebook Pinterest Twitter Youtube Instagram. C andidly, growing up a Taurus was not my favorite thing. Thinking about it now just conjures memories of opening a teen magazine to a feature about nail polish colors for your zodiac sign, and because of the characteristics of a Taurus, I'd get something like "neutral, because you're earthy.
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Close Close. Do NOT think the beauty-dupe from Aldi will hold sway with this gal. A post shared by Adele adele. What actually drives this is a deeply-held desire to ponder and consider their every move as well as yours. They like to analyse… everything. Taureans are intensely physical creatures- they revere the pleasures of the material world rather than imaginative capers or fantasy stories. So: food, drink, chilling, pampering, shopping, sex. That activity-combo is what makes Taurus tick.
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Natural-born food bloggers!
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