The potential effect of Garlium GEM HCTM as a tick control agent in cattle

Abstract

As resistance to chemical acaricides increases amongst tick populations worldwide, the investigation of natural remedies that have an acaricidal or tick repellent effect has become essential in the search for alternatives for sustainable tick control. Garlium GEM HCTM (Garlium) is a natural concentrated garlic product that was fed to eight of 16 Bonsmara steers (average live weight of 215 kg) supplemented at a rate of 2 g Garlium per animal per day in their daily feed ration over a period of 43 days. The other eight steers served as controls and were not supplemented with Garlium. All animals were infested with the same number of Rhipicephalus appendiculatus adults and Rhipicephalus microplus larvae by placing the ticks in cotton bags attached to the ears and the body of the steers, respectively. Engorged female ticks were collected after detachment and kept in a temperature and humidity-controlled mini-acaridarium to lay eggs. The number of attached ticks (both male and female) was also determined, as well as the hatchability of the eggs that were laid. Blood samples were collected from the animals intermittently on predetermined days to determine the effect of Garlium on whole blood composition. The results were analysed by a two-sample t-test method. In general, the results did not show a significant advantage of dietary supplementation of Garlium to Bonsmara steers. Most of the tick parameters were numerically improved, but due to the large standard deviations observed in the results of the different parameters, the results were not statistically significant (P > 0.05). When calculating the number of larvae produced by female R. appendiculatus ticks per host, a 19.1% reduction (P > 0.05) in the number of larvae was observed. Garlium treatment tended to reduce the number of R. microplus larvae produced per host by 42.3 % (P = 0.10). Supplementing Garlium to the cattle had no adverse effect on their haematocrits or haemoglobin concentrations. Thus, there is no evidence that supplementation of Garlium at the rate used in this study would cause anaemia. Garlium supplementation, however, significantly (P = 0.02) reduced the segmented neutrophil count in the treatment group, suggesting that the immune system was challenged to a lesser degree in the treatment group compared to the control group. There was also a tendency (P = 0.10) for haematocrits and lymphocyte counts to increase with Garlium supplementation. Although the potential repellent effect of Garlium supplementation on tick infestation under field conditions was not investigated in this study, and although there were no statistically significant differences in tick parameters between the treatment and control groups, the effect of reducing the number of larvae produced per host by approximately 20% and 40%, respectively, for the two tick species, may be of economic benefit to commercial cattle farmers.