Incidence of ruminite and liver abscess of feedlot bullocks fed high concentrate diets containing feed additives

The aim of this study was to evaluate the effects of polyclonal antibodies preparation (PAP) and/or monensin (MON) on the morphology of the rumen papillae, incidence of ruminate (IR) and liver abscess in feedlot bullocks. Seventy-two bullocks Brangus (261.04 ± 34.73kg) were housed in 24 pens (3 bullocks/pen) with6 replications per treatment. The experimental design was completely randomized 2 x 2 factorial, the factors werethe inclusion or not of MON and PAP.After slaughter, the evaluations were performed. For the livers, both the percentage of abscesses and the severity of them were lower (P< 0.01) in animals fed diets with PAP than those fed MON. The inclusion of MON in the diet was only effective in reducing (P< 0.01) the severity of the abscesses in relation to treatment without this additive. There was no effect (P> 0.05) of additives on the IR. The treatment with MON had higher (P = 0.07) surface absorption/cm² wall of the rumen and greater (P = 0.10) papillary area compared to treatment without this additive. Number of papillae/cm² wall and average area of the papillae showed no difference among treatments. The use of PAP was effective in reducing HA as well as the severity the same, but was not able to improve the shape and structure of the ruminal papillae, as observed with the use of MON.