Feasibility of a "leader-follower" grazing system instead of specialised paddocks with regard to integrated gastrointestinal control in small ruminant farming.

Abstract

In the humid tropics, small ruminant farmers have to deal with gastrointestinal parasitic nematodes (GIN), among which anthelmintic resistant (AR) populations are rapidly spreading. Although targeted selective treatments (TSTs) are being increasingly used in breeding stock, suppressive drenchings remain the rule in younger animals, for safety and ease of implementation. Until now, the weaned animals are grazed on dedicated plots, making the selection and spread of AR parasites inevitable. Given that GINs disseminate through pastures, we compared the usual grazing system (control) to a "leader-follower" grazing system (LF) for managing the entire GIN population at the farm scale. There were no significant differences between treatments for the dam reproductive parameters and level of GIN infection nor for the pre-weaning death rate of the kids. The 70-day weight of the litter was significantly lower for LF than for control goats (9.71 vs. 11.64kg, P < 0.05). Although they were more infested with GIN (1860 vs. 966epg, P < 0.05), the LF weaned animals grew faster (53.4 vs. 40.8gday(-1), P < 0.05) and their death rate was lower (4.0 vs. 7.7%, P < 0.05). The overall animal output was estimated to 1010 [911; 1086] vs. 966 [885; 1046] kg LWha(-1)year(-1), for LF and control grazing systems, respectively. Additionally, the LF grazing system would make the stocking rate easier to manage. Therefore, it is to be recommended as a complement of TSTs in sustainable small ruminant farming.