[Variations in the concentrations of certain blood constituents during the day and from day to day in alpine goats in mid lactation (author's transl)].

In the first experiment blood samples were taken once a fortnight at 7 a.m., 10 a.m., 1 p.m. or 4 p.m.. In the second experiment samples were taken twice a week at an interval of 1, 2, 4 or 7 days. Significant individual variations were observed for lipids (79%), serum glutamic oxalacetic transminase (SGOT, 59%), urea (40%) and glucose (34%), but not for non-esterified fatty acids (NEFA) or beta-hydroxybutyrate (BHB). Concentration of the blood constituents analyzed varied according to the time of sampling and during the week, except for lipids, albuminemia and SGOT. Levels of BHB and glucose rose steadily until 1 p.m. whereas urea increased rapidly from 7 a.m. to 10 a.m. By contrast, NEFA decreased strongly between 7 a.m. and 10 p.m. Concentration of blood glucose, BHB and NEFA did not vary with energetic balance when nutriment requirements were covered. The results of these experiments indicate the importance of respecting standardized conditions for blood sampling with ruminants, in particular regarding the time of feeding.