Monensin controlled-release capsules do not change performance and metabolic profile in unchallenged beef cattle

ABSTRACT

Background: Some additives are able to improve animal performance in growing and finishing periods. Monensin was firstused to control coccidiosis in poultry and was extended to other animals, like ruminants, to act also as a growth promoterand improve cattle performance. In this species, monensin improves the synthesis of propionic acid in the rumen anddecreases methane synthesis and protein degradation, resulting in better performance in protein and energy metabolism.The objective of this study was to evaluate the use of monensin controlled-release capsules on animals grazing Loliummultiflorum intercropped with Trifolium repens on metabolic profile and performance.Materials, Methods & Results: Thirty Hereford cows were randomly distributed into two groups control (CG) and monensingroup (MG). Monensin was individually administered by controlled-release capsules placed in the rumen through oroesophageal pathway. All animals were identified through earring and kept under the same management condition, grazingon upland pasture mixture of Trifolium repens and Lolium multiflorum. Data from biochemical profile and performancewere collected during 45 days. Blood samples started on the day of monensin controlled-release capsule placement (day0) and continued in periods of 15, 30 and 45 days, after initial placement. Serum levels of albumin, glucose, urea, lactatedehydrogenase (LDH) and aspartate aminotransferase (AST) were evaluated using colorimetric diagnostic kits. In the rumen fluid, pH was measured and protozoa count was performed. All statistical analyses were made using software SAS.Albumin, AST, glucose, LDH and urea were analyzed through MIXED procedure and Tukey-Kramer test was applied forcomparison of means. For average daily gain, the orthogonal polynomials test was applied. Treatments did not differ inBSC, body weight and average daily gain (ADG). None of these performance parameters were significantly affected...(AU)