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Performance, Ruminal Fermentation and Blood Constituents of Lambs Fed N,N-Dimethyldodecanamine and Chlortetracycline

University of Maryland, College of Park 20740

Abstract

Three lamb growth trials were conducted to compare the effects of the tertiary amine N,N-dimethyldodecanamine (DDA) and chlortetracycline (CTC) in the diet on feedlot performance, ruminal fermentation and blood constituents. In trial 1, five lots of 10 lambs each (avg wt 21 kg) were fed 0, 25, 50 or 100 ppm DDA or 25 ppm CTC in the diet. In trial 2, eight lots of 10 lambs each (avg wt 25 kg) were fed 0, 25 or 50 ppm DDA or 25 ppm CTC (two lots/treatment). Trial 3 was a replicate of trial 2 conducted with 80 lambs averaging 22 kg. In all trials, the basal diet was a 65% concentrate, 10% alfalfa meal, 25% wheat straw pelleted mixture. Feedlot performance was improved by both CTC and DDA in trials 1 and 3 and dressing percentage was greatest for DDA fed lambs in these trials. There was no response to CTC or DDA in trial 2. This study suggests that DDA at 25 to 50 ppm in the diet improves performance of growing lambs under the same conditions for which CTC improves performance. There were no apparent inhibitory effects on ruminal fermentation or ²⁴ sterol reductase, as shown in other studies at higher DDA treatment levels.

¹ Ruminant Nutrition Laboratory, Anim. Sci. Inst. ARS, Beltsville, MD 20705.

² Milk Secretion and Mastitis Laboratory, Anim. Sci. Inst., ARS, Beltsville, MD 20705.

³ Current address: Adelphi, MD 20783.

⁴ Dairy Sci. Dept., Univ. of Maryland, College Park. Current address: Medical College of Ohio, Toledo 43614.

⁵ Insect Physiology Laboratory, Plant Protection Inst., ARS, Beltsville, MD 20705.

⁶ The authors gratefully acknowledge the assistance of Charles Jackson, Jr., Dennis Hucht, Peter Rakowsky and Adrian Kozak in the collection and preparation of samples and Tom Mullinix for care and feeding of the lambs.