MARE MILK-PRODUCTION AND COMPOSITION - PARTICULARITIES AND FACTORS OF VARIATION

This paper deals with the main particularities of mare milk yield and composition, in comparison with other species. Lactating mares produce in the first month of lactation between 2 and 3.5 kg milk per 100 kg live weight. This value is slightly higher than production of dairy mares and much higher than that of lactating cows. Mere milk is very poor in fat; proteins are characterized by a low proportion of caseins (50-60%). Mean difference of milk yield between saddle and heavy breeds is explained by their liveweight but infra-breed variations do not depend on weight Body condition of mares has only a small influence on their milk yield when they are fed ad libitum. Fat mares produce milk richer in fat than thin mares. Composition of the diet and especially the forage:concentrate ratio do not modify to a large extent milk yield of mares fed ad libitum. The increase in the proportion of concentrates results in a decrease in butterfat and protein content and in a decrease in the proportion of linolenic acid. A shortage in nitrogen supply can result in a decrease in milk yield. A possible relationship between nitrogen supply and milk secretion is shown.