Ionóforos em dietas para bovinos de corte : estudo meta analítico

Abstract

We used the meta-analytical approach to evaluate the effects of the use of different ionophores (monensin, lasalocide and laidomycin) on performance and ruminal parameters of beef cattle of different categories, breeds, and feeding systems from 21 peer-reviewed articles. . The effects of the use of ionophores on beef cattle feeding were evaluated through the crude mean differences (DMB) between treatments (with ionophores) and the control (without any additive). Treatment averages (effect size) were weighted by the inverse of variance using a random effect model. In general, the addition of ionophores did not affect dry matter intake (CMS; P = 0.59), dry matter digestibility (DMS; P = 0.66); ruminal pH (P = 0.76) and ruminal acetate concentration (P = 0.58). However, ionophores increased final weight (P = <0.01), average daily gain (P = <0.01), propionate concentration (P = <0.01). However, there was a reduction in ruminal butyrate concentration (P = <0.01). Heterogeneity was considered between low and medium (I2 statistics <25 and 26-50% respectively), for almost all response variables, except for FP (I2 = 94.99%), DMS (I2 = 99.57%), pH (I 2 = 83.22%). %). A meta-regression was performed to evaluate the covariates: genetic group, animal category, feeding systems and ionophores (dose mg / kg DM). We observed that the feeding system tended (P = 0.08) to affect rumen pH. We conclude that the beneficial effect of ionophores on beef cattle performance was evident in this meta-analysis. Ruminal modulation provided an increase in propionate concentration, which was converted into weight gain. Its effects on dry matter intake, dry matter digestibility, acetate production and ruminal pH were not evidenced.