COMPOSITION OF MARES COLOSTRUM AND MILK - FAT-CONTENT, FATTY-ACID COMPOSITION AND VITAMIN CONTENT

Changes in the fat content, fatty acid composition and vitamin content of mares colostrum and milk during the first 45 days of lactation wer e studied. Milk samples (300-800 cm(3)) from 29 lactating mares were c ollected daily at the beginning of lactation and weekly from 5 to 45 d ays post-partum. Colostrum and early milk samples were obtained by han d, without oxytocin administration, while the foal nursed. Later milk samples were from mixed milk of the totally-milked udder. Each sample was analysed for total solids, fat content, fatty acid composition and vitamin content by conventional methods and gas chromatography.The to tal solids and the fat contents, respectively, of the colostrum and mi lk were 24.25-26.28% and 2.85-2.93% on the first day of lactation, 12. 15-12.78% and 2.05-2.17% on days 2-5 and 10.37-10.61% and 1.04-1.32% o n days 8-45 of lactation. The concentrations of octanoic, decanoic, do decanoic, myristic and palmitoleic acids increased over time while ste aric, oleic, linoleic and linolenic acids decreased. The fatty acid co mposition of mares' milkfat was very different from that of cows milkf at. Mares' milkfat contained octanoic, decanoic, dodecanoic, linoleic, linolenic, stearic, myristic and palmitic acids, respectively, in rat ios of approximately 9.6, 3.1, 2.1, 4.4, 224, 0.2, 0.6 and 0.5 times t hose of the concentrations in cows' milk. On the basis of the differen ces in fatty acid composition, a new method was developed to determine the amount of cows' milk mixed with mares' milk. Contents of vitamins A, D-3, K-3 and C in colostrum (0.88, 0.0054, 0.043, 23.8 mg kg(-1)) were found to be 1.4-2.6 times the levels in normal milk (0.34, 0.0032 , 0.029, 17.2 mg kg(-1)). No significant difference was found between the vitamin E contents of colostrum and milk (1.342 and 1.128 mg kg(-1 )). Vitamin contents of mares' milk were very similar to those in cows ' milk.