1883
Concentration of vitamin B12 in colostrum and milk from dairy cows fed different energy levels during the dry period
Bovine colostrum and milk are an excellent source of vitamin B12 for calves and humans, respectively, who rely on exogenous sources to meet their vitamin B12 requirements. The aim of the experiment was to evaluate vitamin B12 concentration in colostrum and milk from dairy cows fed different levels of energy during the dry period. A total of 84 Holstein cows were assigned to one of the following dietary treatments 60d before the expected calving date: 1) High energy one-group dry cow diet (HE; 1.35 Mcal NEm/kg DM; 56% corn silage, 12% wheat straw, and 32% concentrate mix on a daily DM basis); 2) Low energy one-group dry cow diet (LE; 1.14 Mcal NEm/kg DM; 28% corn silage, 36% wheat straw, and 36% concentrate mix on a daily DM basis); or 3) Intermediate step-up diet (IE; low energy diet from dry off until 30d before the expected calving and then switching to a diet representing a 50:50 blend of the low and high energy diets until parturition). After calving, all cows were fed the same diet using a TMR (44% corn silage, 13% grass silage, and 43% concentrate mix on a daily DM basis) until 42 days in milk (DIM). Colostrum samples were taken at the first milking after the parturition and milk samples were taken during the morning milking at 11 and 39 ± 2 DIM. Data were analyzed using treatment, time as well as treatment x time interaction as fixed effects. A significant treatment × sample interaction was observed (P = 0.02; Table 1). Vitamin B12 concentration in colostrum differed among treatments (P = 0.0002) whereas no diet effect was observed on milk samples (P > 0.97). Colostrum from LE cows had a vitamin B12 concentration higher than IE cows (P = 0.001; Table 1). In summary, results suggest that energy levels in diets during the dry period could change vitamin B12 concentration in colostrum but had no effect later on milk concentration of vitamin B12.
Table 1. Vitamin B12concentration in colostrum and milk according to treatments
Vitamin B12 (pg/mL) |
HE |
LE |
IE |
Colostrum |
27,815ab ± 1,353 |
31,677b ± 1,353 |
23,502a ± 1,378 |
Sample 1 |
3,932a ± 1,353 |
3,701a ± 1,378 |
3,774a ± 1,378 |
Sample 2 |
3,339a ± 1,353 |
3,125a ± 1,378 |
3,000a ± 1,378 |
a,bMeans in the same row with different superscripts differ (P < 0.05)
Keywords:
Dairy cow
Vitamin B12
Colostrum