Capacity of high milk yielding goats to utilize cultivated pastures

Abstract

Nine experiments were carried out at the experimental station of Le Pradel (south-eastern France) from 1991 to 2000 on the management of grazing high milk yielding goats (800 – 1100 kg milk/goat/year) to compare continuous vs rotational grazing, the early or late turn out and different managements of concentrate supplies so as to get optimal milk production and composition. Two experiments comparing during 3 years and 100 days two feeding systems, indoors exclusively or based on grazing, showed that grazing covered more than 50% of energy requirements of goats and that the milk production and fat and protein percentages were not significantly different between the two feeding systems. In a third experiment no significant difference in milk production and composition was observed between goats managed on rotational or continuous grazing. A fourth experiment showed that a better milk production and composition was achieved with an early turn out (around 1st March) in comparison with a later turn out around 31 March. Four experiments lasting 12 – 16 weeks compared various levels of concentrate supplies in grazing goats. The higher concentrate supply increased milk production in a limited way, particularly above 0.8 kg of concentrate/day/goat and with grass of high dietary value (10 g milk per 100 g concentrate vs 40g concentrate with lower quality grass). Milk composition was very little influenced. A last experiment and several previous experiments investigated the effects of the concentrate composition. The nature of nitrogen sources (highly or little degradable protein in the rumen) more strongly influenced goat milk production than the type of energy resources (starch vs fibre and fat). Thus an annual production around 1000 - 1100 kg of milk in multiparous dairy goats can be obtained with a feeding system based on cultivated grazing which covers the main part of energy requirements (from around 50 to 75%). For that, the genetic potential of goats has to be sufficient, the daily grazing duration has to reach 10 to 11 h/day, the supplies of conserved fodders have to be very limited or withdrawn, the concentrate supplies have to be limited to around 0.8 kg/goat/day, and the pastures and animal behaviour on grazing need to be managed by goat farmers with daily accurate observations and controls.