Body reserves of Charolais cow. Relations with reproductive performance

Abstract

The body stores of a Charolais cow weighting 700 kg can reach 130 kg : fat is the most important component (85 kg), largely before muscles (26 kg). Subcutaneous fat has a higher relative change, so it is possible to have a good estimation of the total fat with a condition score scaled from 0 to 5. Mobilisation of body reserves is made on a hierarchical way : lipids are firstly utilised, in proportion of 75% per kg of weight loss. This proportion decrease appreciably for very lean cows which mobilisation overgoes 80 kg of body mass. Restoration of the reserves depend on intake capacity of the cow at pasture, which is directly correlated with the size. An important economy of feeding stuffs can be achieved from the use of body resources, but a good efficiency of reproduction must be conserved (risks of increasing postpartum anoestrus and decreasing fertility). Thresholds of condition scores proposed at calving change from 2.5 to 2.0 for different level of nutrition given during reproduction period. The duration of lactation allows to manage condition score at housing, so it is possible to anticipate condition score at calving when total alimentary resources are known. Body condition score is absolutely necessary for an economic management of the suckler cow.