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Tissue Residues, Performance and Ruminal and Blood Characteristics of Steers Fed Ronnel and Activated Carbon

U. S. Department of Agriculture

Abstract

Sixteen steers averaging 362 kg body weight were used in a 90-day trial to study the effects of feeding ronnel, a systemic grub control insecticide and larvicide, and activated carbon (AC) on tissue ronnel concentration, the systemic potency of ronnel, feedlot performance, diet digestibility and ruminal and blood characteristics. The steers were individually fed a 70% concentrate diet and assigned to a 2 x 2 factorial in which either 0 or 4.5 mg ronnel/kg body weight daily were fed, and either 0 or 5% AC was added to the diet. AC decreased the accumulation of ronnel in fat tissue by 31%. Ronnel was not detected in liver tissue. The addition of AC to diets of ronnel-fed steers markedly reduced the toxicity of ruminal fluid to house flies, but did not significantly affect the toxicity of whole blood to stable flies. Ronnel and AC had no significant effect on gain, feed intake, diet digestibility and nitrogen balance, but daily gain and daily feed intake were somewhat greater for ronnel-fed steers (1.2 kg vs 1.0 kg and 11.3 kg vs 10.5 kg). Daily fecal mineral excretion appeared greater for AC-fed steers (15.6 kg vs 13.2 g). Ruminal characteristics were not significantly affected by ronnel and AC, but the molar percentage of acetate was higher (52.9 vs 47.5) in ronnel-fed steers. AC had little effect on blood characteristics. Ronnel-fed steers had higher levels of plasma, total essential amino acids (95.0 vs 76.8 µMoles/ml), nonessential amino acids (143.9 vs 124.4) and ammonia (57.3 vs 47.7). These differences were partly due to intake differences. Some differences in individual amino acids were associated with the ronnel treatment but were not related to performance.

¹ ARS, Nutrition Institute, Ruminant Nutrition Laboratory, Beltsville, Maryland 20705.

² Formerly, Animal Husbandry Research Division, ARS, Beltsville, Md; now, APHIS, State Federal Diagnostic Laboratory, 1276 Plank Road, Baton Rouge, La. 70808.

³ The authors gratefully acknowledge the assistance to Mr. L. I. Colbert in conducting the digestion trials and Mr. D. F. Hucht for tissue residue analysis.