Investigation of tick infestation on udders of beef cows and the related effects on calf survival and growth to weaning in the Mnisi tribal community

Abstract

Ticks are important ectoparasites and vectors of human and animal diseases in many countries including South Africa (Matayo, 2001). In Matabeleland, south province, some recent work has been done by VEDMA consulting group (2005) and confirmed that tick infestation and tick borne diseases (TBD) are some of the most important conditions affecting livestock productivity (Ndhlovu, 2008). Ticks are responsible for direct damage to livestock skins and hides because of their feeding habits, damaging udders, teats, scrotum and other exposed animal parts due to infestation of damaged sites by maggots and secondary microbial infections (Norval 1983, Meltzer and Norval 1993; Dreyer, Fourie and Kok, 1998). Productivity losses which can occur (Norval et al., 1988; 1989; Stachurski et al., 1993; Meltzer et al., 1995; Jonsson, 2006) may not be obvious to communal small-scale farmers. Heavy infestations can cause loss of blood, reduce the rate of live-weight gain and lower milk yield, whilst the long mouthed ticks downgrade the quality of the hides (De Castro, 1997). The objective of the study was to investigate tick infestation and distribution on cow udders, evaluating the level of udder damage caused by ticks and the impact this has on growth of calves until weaning age and survival rate. In coming up with a strategy to improve the calf survival to weaning age and reducing tick infestation rate on cow udders in extensive cattle production systems, an understanding of manipulation of factors which contribute to tick attachment ,milk availability for calf suckling and calf growth and development to weaning age are to be considered. Not many farmers practice regular tick control strategies because of ignorance, negligence and poverty (Davidi, 2001). The South African government has strategically and traditionally provided the means and infrastructure for tick control in communal farming areas (Stevenset al., 2007) as an incentive for farmers to present their animals for weekly inspection and disease control interventions. Control of ticks and tick-borne diseases (TBDs) in small-scale sectors has been one of the major initiatives implemented by the Mpumalanga Veterinary Services (MVS). Despite their well-known disadvantages, resistance, environmental pollution, residues in meat, milk, hides and skins and natural toxicity, acaricides are the backbone of tick control as they are effective both in the short-term by cleaning the animal of ticks and in the long-term in reducing tick burdens. The prevalence of tick attachment on dam udders was investigated, investigating the level of tick attachment (TAS) and level of udder damage (CUS) to lactating cows. This in turn allowed for further evaluation of the impact TAS and CUS scores had on calf growth to weaning (ADG). The degree of tick infestation on dams showed a tendency towards having a significant relationship to the dam’s body condition score (P=0.1), and the udder score of lactating dams is associated with the dip-tank the dam dips at on a regular basis. The dip-tank the calf and dam are associated with has an influence to growth and development of calf (ADG), (P<0.05). Calf time to death was evaluated against calf associated independent variables, showing no significant association to calf time of death, P>0.05.