Agricultural Reviews

There are number of internal and external factors that affect the production performance of animals, among which parasites and parasitism are major of concern constraints to animal's productivity especially in tropical countries. The usual mode of control of these gastro-intestinal parasites (GIP) by based on the repeated use of anthelmintics is now strongly questioned because of the increasing development of resistance to these molecules. Among the alternative methods to anthelmintics currently available, the manipulation of host nutrition in order to improve the host resistance and/or resilience to parasitic infections seems to represent one of the most promising options to reduce the dependence on conventional chemotherapy and to favor the sustainable control of GIP. This paper will discuss the interactions between nutrition and parasitism and will also refer to quantitative (influence of protein, energy, micronutrients and other phyto-additives) as well as to qualitative (organic livestock farming, foraging) aspects of the diet. The beneficial effect of nutrition, more specifically, the importance of protein nutrition for the maintenance of host immunity to parasitism, the potential use of novel crops and possibilities for biological control have also been discussed. Biological control of parasitic nematodes seems to hold promise for the future, but to be able to assist producers; the optimal delivery system needs to be refined and further developed. In addition, more work will be needed to define anthelmintic resistance, non-chemical alternatives to parasite control, modulation of immunity to parasites by genetic and nutritional factor, integrated parasite control strategy and the best use of these technologies in different geographic regions. Internal parasites are a potentially serious threat to the health, welfare and productivity of organically managed livestock, the ultimate goal of which is to eliminate dependence on antiparasitic drugs, however this is rarely achieved in practice. It is now realized that chemical anthelmintic treatment, on its own, may not provide a long term strategy for managing parasite in grazing ruminants. There is a growing awareness for strategic nutritional supplementation with far reaching consequences, viz. increased production of meat, milk and wool, and also of its quality, growth and reproductive efficiency, parasite control, enhancement of immunity and disease resistance.