Lactational response to a feed supplement containing fermentation products, cobalt, dextrose, and lactose.

A feed supplement containing dried microbial fermentation products, cobalt, dextrose, and lactose was fed at 15 g per cow daily to 10 lactating Holstein cows in a switchback experiment with three periods of 5 wk each. Cows averaged 80 days postpartum and produced from 28 to 45 kg daily at the beginning of the experiment. Throughout the 15-wk experiment, cows were fed a 19% crude protein concentrate mix at 1 kg per 3 kg milk produced, 2.3 kg alfalfa hay daily, and corn silage for ad libitum intake. Milk production and composition were similar when supplemented or unsupplemented diets were fed. Means with and without feed supplement were: milk, 28.1 and 28.2 kg/day; fat, 3.57 and 3.55%; protein, 3.07 and 3.08%; and total solids, 12.28 and 12.18%. Daily consumption of dry matter as concentrate (10.4 and 10.2 kg), hay (2.1 and 2.1 kg), and corn silage (8.4 and 8.4 kg) was similar with or without the additive. Estimates of cobalt content of diets fed indicated that cows were consuming more than adequate amounts of cobalt without the supplement. Under conditions of this experiment, there was no advantage for feeding this supplement.