Effect of a calcareous algae and monensin on feed intake and rumen parameters of cattle fed abruptly high concentrate diets

Abstract Text: Additives are used in high concentrate diets to prevent metabolic disorders. The use of calcareous algae (Lithothamnium calcareum), a natural and renewable product, may be an alternative. The effect of a calcareous algae product (Top Buffer^® Sanphar, Campinas, Brazil) and monensin (Bovensin^® Phibro, Guarulhos, Brazil) on feed intake, rumen pH, short chain fatty acids, lactate and ammonia nitrogen concentration in the rumen of Nellore steers transitioned abruptly to a high concentrate diet was evaluated.. On d 1, the diet of all animals was abruptly changed from hay to a high concentrate diet (82.41% corn, 7.75% sugar cane bagasse, 6.78%, soybean meal, 1.29% urea and 1.77% mineral mixture). The diet was provided once a day during four periods of 21 days, and treatments consisted of different additives: limestone 7.1 g/kg DM, calcareous algae product 7.4 g/kg DM, limestone and monensin 30mg/kg DM and calcareous algae product and monensin 30mg/kg. Rumen pH was measured continuously from d -3 to d 21 through an indwelling pH probe (Dascor, Escondido, Canada) inserted in the rumen. Rumen samples were taken six hours after feeding on days -1, 4, 7 and 14. Feed intake was adjusted daily, allowing ten percent orts. There was no interaction (P>0.050) between calcium source and monensin for feed intake, ruminal pH and total concentration of short chain fatty acids. There was no influence (P>0.050) of calcium sources on feed intake, total concentration of short chain fatty acids, acetate:propionate ratio, lactate and ammonia nitrogen concentration. Diet with the calcareous algae product resulted in higher (P=0.040) average rumen pH than limestone (6.09 vs. 6.01, respectively) and lower (P<0.001) time bellow pH 5.2 (1hr29min vs. 2hrs43min). Treatments with the presence of monensin resulted in higher (P=0.008) concentration of ammonia nitrogen (4.69 vs. 3.94 mg/dL without monesin) and lower (P=0.023) time bellow pH 5.2 (1hr45min vs. 2hrs27min without monensin). Calcareous algae product was more efficient in controlling rumen pH than limestone without influencing feed intake and the concentration of short-chain fatty acids. Monensin was also beneficial in preventing rumen disorders.

 Keywords: Nellore, additives, acidosis