Cobalt-lactate inclusion in a high forage total mixed ration fed to late lactation dairy cows
Cobalt-lactate is a highly soluble source of Co in the rumen. Prior research evaluating higher Co feeding rates has been shown to increase ruminal fiber digestion. Feeding high forage rations to late lactation dairy cows to improve income over feed cost could potentially benefit from feeding higher ruminal soluble Co rates to enhance ruminal fiber digestion and nutrient digestibility. Twenty-four late-lactation (238 ± 68.8 DIM and 36.5 ± 5.4 kg milk) Holstein dairy cows (10 primiparous and 14 multiparous), were blocked by milk yield, DIM, and parity and randomly assigned to 1 of 2 treatments. Treatments included: 1) CONTROL diet containing cobalt carbonate fed at 58 mg/cow/d and 2) TEST diet being the same basal diet but including an additional 5 g/cow/d of a 1% Co-lactate product (Co-Max®) to increase levels of cobalt by 50 mg/cow/d. Rations were 70% forage and 30% of the respective experimental grain mix on a DM basis with the forage blend consisting of 60% alfalfa baleage and 40% corn silage (DM basis). Cows were fed the CONTROL ration during the covariate period of 7 d followed by 4 weeks of data collection when CONTROL and TEST diets were fed. Milk production (26.2 and 25.8 kg/d for CONTROL and TEST, respectively throughout results) was similar (P=0.72). Dry matter intakes (22.9 and 23.1 kg/d) were similar (P=0.8). Concentration of milk fat (4.13 and 4.13%), milk protein (3.53 and 3.40%) and lactose (4.68 and 4.71%) were similar (P=0.98, P=0.21, and P=0.66, respectively). Body weights (684 and 673 kg) were not different (P=0.11). Feeding additional Co as cobalt-lactate did not influence milk production, milk composition, dry matter intake or body weight for lactating dairy cows fed a high forage ration.