Influence of nutrition on parasitism in periparturient dairy ewes

Partington, Elizabeth Claire (2005). Influence of nutrition on parasitism in periparturient dairy ewes. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000f623

Abstract

Influence of Nutrition on Parasitism in Periparturient Dairy Ewes Increased anthelmintic resistance has lead many researchers to investigate alternative methods of parasite control. It is believed that most larval contamination of the pasture is derived mainly from the mature breeding ewe due to the periparturient rise (PPR) in faecal egg counts (FECs). The aim of this study was to determine if manipulating the dietary supply of metabolisable protein (MP) or fish oil to the periparturient ewe can moderate the PPR.

The first experiment investigated the effects of increased MP supply and fish oil on the PPR of machine-milked ewes. The second experiment investigated the effects of nematode infection and increased MP supply on the PPR of machine-milked ewes and the third experiment investigated the effects of machine milking compared to suckling twin lambs and the effect of increasing dietary MP on the PPR.

In all the experiments, FECs, peripheral eosinophil counts, blood haematology and metabolite analyses were carried out and milk yields and composition were recorded. Additionally, in Exp.l immunoglobulin titres were determined, in Exp.2 pepsinogen assays were carried out and in Exp.3 blood was collected for lymphocyte stimulation responses. In Exps.2 and 3, the ewes were slaughtered to investigate nematode burden, mucosal mast cell (MMC) and mucosal eosinophil counts.

The dietary treatments had no significant effects on the immunological parameters throughout all three experiments, although in Exp.2 larval challenge increased MMCs, mucosal eosinophils and pepsinogen assays. There was no benefit of increased dietary MP or fish oil on FECs in Exp.l. and no beneficial effect of increased dietary MP on FECs during Exp.2. However, in Exp.3 increased MP reduced the FECs from the twin suckled ewes but had no effect on the machine-milked ewe FECs. The machine-milked ewes had significantly lower milk yields than the suckled ewes and it may be that the machine-milked dairy ewe may not suffer the PPR due to some unidentified mechanism.