MARE MILK-PRODUCTION AND COMPOSITION - PA RTICULARITIES 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 ma res and much higher than that of lactating cows. Mere milk is very poo r in fat; proteins are characterized by a low proportion of caseins (5 0-60%). Mean difference of milk yield between saddle and heavy breeds is explained by their liveweight but infra-breed variations do not dep end on weight Body condition of mares has only a small influence on th eir milk yield when they are fed ad libitum. Fat mares produce milk ri cher in fat than thin mares. Composition of the diet and especially th e forage:concentrate ratio do not modify to a large extent milk yield of mares fed ad libitum. The increase in the proportion of concentrate s results in a decrease in butterfat and protein content and in a decr ease in the proportion of linolenic acid. A shortage in nitrogen suppl y can result in a decrease in milk yield. A possible relationship betw een nitrogen supply and milk secretion is shown.