Mustard meal in dairy rations.

Consumption of 0% mustard meal and 15% soybean meal, 7.5% mustard meal and 7.5% soybean meal, or 15% mustard meal and 0% soybean meal rations did not differ in palatability studies with 10 group-fed lactating cows when the mustard meal was treated with 3% caustic soda. Order of preference was for 0, 7.5, and 15% mustard meal rations when mustard meal was untreated. Twelve lactating cows were in each of two lactation trials to compare the three rations of untreated mustard meal. Milk, milk fat, and solids-not-fat, and milk protein did not differ for either trial. Protein-bound iodine of plasma for all cows were within the normal range. Three cows were placed on each of the three rations and received a minimum of 9 kg per day for 6 mo preparturition to determine goitrogenic effects. All cows gave birth to normal, vigorous calves. Limited organoleptic evaluations of milk indicated that untreated mustard meal may impart a detrimental flavor to milk, but a taste panel could not differentiate between milk from cows on the three rations of treated mustard meal. Twenty-one male and 43 female Holstein claves received either 0, 10, or 20% mustard meal starter rations from birth to 3 mo of age. Growth, feed consumption, or plasma protein-bound iodine did not differ.