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The effect of feeding antibiotic growth promoters on the performance of beef cattle consuming forage-based diets: A review |
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| Authors: | G Bretschneider JC Elizalde FA Prez |
| Institution: | aDepartment of Veterinary and Biomedical Sciences, University of Nebraska, Fair St. at East Campus Loop, Lincoln, NE, 68583 - 0905, USA bConsejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET), Argentina cFacultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata (UNMdP-Balcarce), Balcarce 7620,Provincia de Buenos Aires, Argentina dFacultad de Ciencias Veterinarias (UNCPBA-Tandil), Tandil 7000, Provincia de Buenos Aires, Argentina |
| Abstract: | Scientific literature on the use of antibiotic growth promoters (AGP) in beef cattle consuming forage-diets was reviewed. Database summarizes 136 comparisons between untreated and AGP-treated cattle from 48 bibliographic references. Performance data of cattle receiving AGP either alone or in combination with 17 β-estradiol implants was statistically analyzed. Forage quality, in terms of average daily gain (ADG), differentially influenced (P = 0.1) the effect of AGP on beef cattle performance. As the quality of forage increased, the estimated net ADG response to monensin decreased and that to lasalocid increased. ADG increased quadratically (P < 0.01) with increasing doses of monensin (R2 = 0.71) or lasalocid (R2 = 0.63). Ionophore-dosage level quadratically improved (P = 0.01; R2 = 0.52) feed conversion (FCONV) of cattle without affecting their dry matter intake (DMI; P > 0.1). A linear relationship (P < 0.01) between ADG and dose of tetronasin (R2 = 0.64) or lysocellin (R2 = 0.52) was also observed. The combination of monensin and 17β-estradiol implants resulted in an additive effect on ADG of grazing cattle. The experimental results reviewed show that, in beef cattle consuming forage-based diets, ionophores improve ADG and FCONV in a dose-dependent manner, with little or no effect on DMI. In addition, results suggest that forage quality influences the direction of the ADG response to AGP supplementation in cattle. Summarized data from beef cattle implanted with 17β-estradiol and/or supplemented with monensin indicate that the combined response of these two compounds on cattle grazing high-quality pastures has no effect on ADG over that obtained by 17β-estradiol alone. |
| Keywords: | Growth promoter Ionophore Management Beef cattle Weight gain Meta-analysis |
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