Monensin, virginiamycin and functional oils on rumen health of Nellore cattle fed high concentrate diets without adaptation

Tuesday, July 22, 2014
Exhibit Hall AB (Kansas City Convention Center)
Ana Paula dos Santos Silva , University of Sao Paulo, Pirassununga, Brazil
Roberta Ferreira Carvalho , University of Sao Paulo / FZEA, Pirassununga, Brazil
Claiton Andre Zotti , University of Sao Paulo / FZEA, Pirassununga, Brazil
Madeline Rezende Mazon , University of Sao Paulo, Pirassununga, Brazil
Leticia Silva Oliviera , University of Sao Paulo / FZEA, Pirassununga, Brazil
Saulo Luz e Silva , University of Sao Paulo / FZEA, Pirassununga, Brazil
Paulo Roberto Leme , University of Sao Paulo, Pirassununga, Brazil
Abstract Text:

Feed additives and adaptation strategies are used to prevent metabolic disorders in feedlot cattle. The extent on how additives can contribute to rumen health of Zebu cattle that are not adapted to high grain diets is still unknown. To evaluate the different feed additives on rumen health, 48 Nellore bulls (322 ± 23 kg of BW, 20 months old) were submitted to a diet change, without adaptation, from grass pasture to a high concentrate diet (92% grains) fed ad libitum during 120 days. The treatments were different feed additives added to the basal diet: monensin at 30 mg/kg DM (M30), monensin at 40 mg/kg DM (M40) fed during the first 14 days, decreasing to 30 mg/kg after this period, monensin at 30 mg/kg DM + virginiamycin at 25 mg/kg DM (MV) and functional oils (a blend of castor oil and cashew oil) at 400 mg/kg DM (FO). After 120 days animals were slaughtered and the livers were examined for abscesses. Rumen pH was measured and the incidence of ruminites (IR) was classified according to a 0 to 10 scale. Fragments of 3 cm2 were taken from the cranial sac of the rumen and kept in buffer solution for the measurements of papillae number (PN), papillary area (PA) and absorption surface (AS). PN was counted by 3 evaluators and PA and AS were measured on the UTHSCA Image Tool free software. Animals fed FO diet had higher (P=0.01) daily DMI than M30 and MV. However, there was no difference (P=0.22) between OF and M40.There was no difference among treatments for ADG (P=0.13), final BW (P=0.16) and G:F (P=0.10). No difference (P=0.86) was verified for rumen pH (6.37 ± 0.51). There was no incidence of liver abscesses and low IR (P=0.61; 1,09 ± 1,42). No differences (P=0,90) were found on PN (53.18 ± 14.25), on PA (P=0.60; 0.7 ± 0.26) and also on AS (P=0.82; 38.07 ± 17.89). No metabolic disorders occurred and there was no decrease in animal performance indicating a relative protection of the additives and the possibility of feeding high concentrate diets to Nellore cattle without adaptation. Also, FO, a natural product, may substitute ionophores and antibiotics as additives for rumen protection when high concentrate diets are fed.

Keywords: feed additives, Zebu, feedlot