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Comparison of Ammonium Salts and Urea in Rations for Lactating Dairy Cows¹

Michigan State Univeristy, East Lansing 48824

Abstract

Four isonitrogenous concentrates that contained soybean meal, urea, ammonium propionate or ammonium lactate as supplemental nitrogen sources were fed to 36 cows (nine per treatment) at a level of 1 kg per 2.5 kg milk for 84 days. The concentrate for each cow was mixed with sufficient corn silage to yield a 10% refusal of the complete feed. Rations were fed once daily. Intakes of urea, ammonium propionate and ammonium lactate were 209, 1,170 and 1,151 g per day, respectively.

Milk yields and composition were adjusted by covariance using means of a 14-day standardization period. For soybean meal, urea, ammonium propionate and ammonium lactate, milk yields averaged 23.3, 23.0, 23.8 and 22.7 kg per day; FCM, 19.9, 21.1, 22.7 and 20.9 kg per day; milk fat, 3.0, 3.6, 3.5 and 3.5%; and milk solids-not-fat, 8.84, 8.92, 8.99 and 8.83%. FCM was higher (P< .05) for non-protein nitrogen treatments than soybean meal. Dry matter intakes were 18.4, 18.7, 17.7 and 17.9 kg per day for the respective treatments.

¹ Published with the approval of the Director of the Agricultural Experiment Station as Journal Article No. 6595.

² Present address: McPherson College, McPherson, Kansas.

³ Department of Dairy Science.

⁴ Department of Animal Husbandry.