Gérer les variations des apports alimentaires des vaches laitières au pâturage

Abstract

Grazed pasture is the cheapest source of nutrients for dairy cows and should form the basis of profitable and low input animal production systems. Management of high producing dairy cows at pasture is thus a major challenge in most countries. The objective of the present paper is to review the factors affecting nutrient supply for grazing dairy cows in order to point out areas with scope for improvement on managing variations in nutrient supply to achieve high animal performance while maintaining efficient pasture utilisation per hectare. Reviewing the range in animal nutrient requirements, intake capacity and pasture nutritive values shows that high producing cows cannot satisfy their energy requirements from grazing alone. Favourable to unfavourable situations for grazing dairy cows may be defined according to pasture quality and availability. Predictive models also enable to calculate supplementation level required to meet energy requirements in various situations. Solutions to maintain acceptable level of production per cow and high output per ha are discussed. Strategies of concentrate supplementation and increasing use of legumes in mixed swards are the most promising. It is concluded that there is scope for improving animal performance at grazing given recent developments in our understanding of factors influencing pasture intake and digestion.