A model of the herd functioning to assess the milk production and the feed efficiency in dairy goat systems

Abstract

This paper describes a dairy goat herd model, which simulates the effects of management practices on herd performance. The model is based on the interaction between a decisional system and a biological system. The biological system represents each animal based on a dairy goat model. The decisional system is based on the technical operations of feeding, reproduction and replacement. Three experimental plans were run to test the effects of i) the energy level of the diet and the mean herd production potential; ii) the number of steps within the feeding plan and the length of the breeding season and iii) a simplified management of the herd. The model enables assessing milk production and feed efficiency at both herd and individual levels. The results showed that the feeding level and the mean herd potential have marked effects on milk production and feed efficiency through a dilution effect of the production cost by the quantity of milk produced. The results also showed that the degree of segmentation of the feeding plan modulates the effects of the feeding level. By looking at biological individual variables, it was possible to discriminate management practices which led to similar performances at the herd level. These practices generated different biological risks, which can potentially modulate herd adaptive abilities to environmental perturbations.