Major constituents, leptin, and non-protein nitrogen compounds in mares' colostrum and milk

Five Haflinger mares were hand-milked at 0 h (pre-suckle) and 6 h (postsuckle), 12, 24, 48, 72 and 96 h after parturition. Total solids, protein, fat, lactose, calculated gross energy content, leptin and non-protein nitrogen components (urea, a-amino nitrogen, creatinine and allantoin) were determined. The levels of the major constituents differed significantly in pre-suckle colostrum from subsequent samples. Leptin levels were the highest in whole (9 ng . mL -1 of immunoreactive human equivalent HE 0.48 ng . mL -1 , SEM) and skimmed (7.8 ng HE . mL -1 0.52 ng . mL -1 , SEM) pre-suckle colostrum, declined sharply at 6 hours postpartum, and more slowly subsequently. Mean urea concentration was constant at around 5.0 mM, while a-amino N increased over the observation period and creatinine and allantoin decreased. These findings provide a further indication that mares' milk can be regarded as a functional food. mares' milk / colostrum / major constituents / leptin / non-protein nitrogen Rsum -Principaux constituants, leptine et mtabolites d'azote non protique dans le colostrum et le lait de jument. Cinq juments Haflinger ont t traites la main aux temps 0 (avant tte) et 6 (aprs tte), 12, 24, 48, 72 et 96 heures aprs le poulinage. Les paramtres valus sur ces chantillons ont t les principaux constituants de la scrtion mammaire (matire sche, protines, lipides, lactose), le contenu nergtique brut et la leptine ; en plus, on a considr les teneurs en ure, a-aminoacides, cratinine et allantone. Une diffrence significative a t observe entre les valeurs enregistres dans le colostrum prlev avant la tte et dans les autres chantillons. De mme, des variations dynamiques concernant la leptine immunoractive ont t releves au cours de l'essai : les valeurs taient les plus fortes dans le lait entier (9 ng . mL -1 quivalent de leptine humaine HE 0,48 ng . mL -1 , SEM) et dans le colostrum crm (7,8 ng HE . mL -1 0,52 ng . mL -1 , SEM) prlevs avant la tte. La concentration en ure tait en moyenne de 5,0 mM et la concentration en azote des a-aminoacides dnote des bilans diffrents par rapport celui mis en vidence pour la cratinine et pour l'allantone. Ces rsultats contribuent faire considrer le lait de jument comme un aliment fonctionnel.