Seasonal variation in coat characteristics, tick loads, cortisol levels, some physiological parameters and temperature humidity index on Nguni cows raised in low- and high-input farms

Abstract

Seasonal variations in hair length, tick loads, cortisol levels, haematological parameters (HP) and temperature humidity index (THI) in Nguni cows of different colours raised in two low-input farms, and a commercial stud was determined. The sites were chosen based on their production systems, climatic characteristics and geographical locations. Zazulwana and Komga are low-input, humid-coastal areas, while Honeydale is a high-input, dry-inland Nguni stud farm. A total of 103 cows, grouped according to parity, location and coat colour, were used in the study. The effects of location, coat colour, hair length and season were used to determine tick loads on different body parts, cortisol levels and HP in blood from Nguni cows. Highest tick loads were recorded under the tail and the lowest on the head of each of the animals (P < 0.05). Zazulwana cows recorded the highest tick loads under the tails of all the cows used in the study from the three farms (P < 0.05). High tick loads were recorded for cows with long hairs. Hair lengths were longest during the winter season in the coastal areas of Zazulwana and Honeydale (P < 0.05). White and brown-white patched cows had significantly longer (P < 0.05) hair strands than those having a combination of red, black and white colour. Cortisol and THI were significantly lower (P < 0.05) in summer season. Red blood cells, haematoglobin, haematocrit, mean cell volumes, white blood cells, neutrophils, lymphocytes, eosinophils and basophils were significantly different (P < 0.05) as some associated with age across all seasons and correlated to THI. It was concluded that the location, coat colour and season had effects on hair length, cortisol levels, THI, HP and tick loads on different body parts and heat stress in Nguni cows.

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

“…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.…”

“…Similarly, Asmaa et al [16] found that the lowest number of ticks were observed around the eyes, neck and chest. Ticks prefer hidden and warm anatomical zones on the animal body [8]. Hence, a suitable environment for tick survival is under the tail and perineum, possibly explaining the high number of ticks observed on these body zones.…”

“…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 [17] and Lorusso et al [21] found a lower tick burden in calves compared to older cattle, and Asmaa et al [16] observed a higher infestation rate in older animals of different ruminant livestock species.…”

“…Climate is one of the main factors controlling tick distribution due to its regulatory influence on the tick life-cycle [7]. Changes in environmental conditions may have a positive or negative effect on tick burdens and on the physiological heat regulation mechanisms of infested cattle [8]. Several indices have been developed to monitor the heat stress status in different livestock species.…”

“…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].…”