Effects on metabolic and endocrine traits of feeding colostrum on d 1 and 2, then mature milk up to d 7, or glucose or water on d 1, colostrum on d 2 and 3 and then mature milk up to d 7 were studied in calves. Calves fed colostrum within the first 24 h after birth had significantly higher rectal temperatures, heart rates and respiratory frequencies than calves provided only water or glucose. Significantly elevated plasma nonesterified fatty acid and bilirubin concentrations on d 1 and 2 of life in calves fed only water on d 1 compared with calves of the other groups mirrored reduced energy intake. Fecal consistency was significantly higher during wk 1 of life, and gastrin and glucose-dependent insulinotropic polypeptide increased only on d 1 and/or 2 of life in calves already fed colostrum on d 1, expressing improved functioning of the gastrointestinal tract. Significantly higher plasma globulin levels up to d 7 in calves fed colostrum on d 1 than in those starting colostrum intake only on d 2 demonstrated significantly enhanced efficiency of gamma-globulin absorption. Furthermore, significantly higher circulating glucose, albumin, insulin, insulin-like growth factor-I concentrations and significantly lower urea levels in calves fed colostrum on d 1 compared with those fed colostrum starting on d 2 of life indicated stimulation of anabolic processes. In conclusion, colostrum intake by calves within the first 24 h of life is needed not only for an adequate immune status, but also to produce the additional important and favorable effects on metabolic and endocrine traits and on vitality.

To study whether a delayed start of colostrum feeding in calves affects plasma lipids, fatty acids and fat-soluble vitamins, one group was fed colostrum (milkings 1-4) on d 1 and 2, then mature milk up to d 7, whereas two other groups were fed glucose or water on d 1, colostrum (milkings 1-4) on d 2 and 3 and then mature milk up to d 7. In calves fed colostrum on d 1, starting 5-7 h after birth, plasma concentrations of triglycerides, phospholipids, total cholesterol and of essential and nonessential fatty acids in triglyceride, phospholipid and cholesterol ester fractions as well as of carotene, retinol and alpha-tocopherol up to d 7 were significantly higher than in calves in which colostrum feeding started after >24 h of life. On the other hand, plasma concentrations of vitamin B-6, vitamin B-12 and folic acid were not influenced. Results indicated reduced efficiency of absorption of colostral fatty acids and of fat-soluble vitamins, but not of (selected) water-soluble vitamins, if colostrum is not fed on d 1 of life. In conclusion, colostrum intake within the first 24 h of life is required for an adequate plasma lipid, essential fatty acid, carotene, retinol and alpha-tocopherol status in the first week of life of calves.

Summary Plasma immunoglobulin G (IgG) concentrations and γ‐glutamyltransferase (GGT) activities were measured in neonatal calves fed colostrum on days 1 and 2 of life, then milk up to day 7 (group C), while groups G and W were fed glucose or water, respectively, on day 1, colostrum on days 2 and 3 and milk up to day 7 of life. Glucose administration in group G on day 1 caused significantly more marked hyperglycaemias than in group C, while glucose concentrations in group W remained low. However, glucose concentrations on day 2 were significantly higher in group C than in groups G and W. Concentrations of IgG in group C significantly increased on day 1 and decreased after day 2, while GGT activity significantly increased after the first colostrum feeding only and decreased on day 2. Concentrations of IgG and GGT activity in groups G and W remained low on day 1 and increased on day 2. However, IgG remained significantly lower up to day 7 than in group C, while GGT reached the values of group C on day 2. Concentrations of IgG and activities of GGT on day 2 tended to increase less in group W than in group G. In conclusion, both plasma IgG concentration and GGT activity increased after colostrum intake, but only IgG remained elevated and thus informed on colostrum intake up to day 7. Intake of glucose relative to water did not significantly reduce the rise of IgG and GGT.