Effect of dietary sodium bicarbonate supplementation on fermentation characteristics and ciliate protozoal population in rumen of lambs

Effects of sodium bicarbonate (NaHCO3) inclusion on rumen fermentation characteristics and ciliate protozoal population in high concentrate-fed lambs were studied. Twenty-four weaner (90 days old) Malpura lambs divided into four equal groups (G1, G2,G3 and G4) were fed basal (25:75 roughage and concentrate) diet (G1) or basal diet supplemented with 0.75% (G2), 1.50% (G3) and 2.25% (G4) sodium bicarbonate for 90 days. Daily dry matter (DM) intake and digestibility of organic matter (OM), crude protein (CP), gross energy and plane of nutrition were similar in all the groups while cellulose digestibility was higher in G4 than in G2 and G1. Ruminal pH increased (P <0.05) with increasing levels of dietary sodium bicarbonate. Concentrations of total volatile fatty acids (TVFA), total nitrogen and trichloroacetic acid-precipitable nitrogen (TCA-ppt.-N) were higher while ammonia nitrogen was lower in the rumen fluid of G4 and G3 than in G2 and G1. The number of total protozoa, Isotricha, Dasytricha, large and small spirotrichs were higher (P <0.01) in the rumen of G4 and G3 than in G2 and G1. Total live weight gain and average daily gain were also higher in lambs supplemented with sodium bicarbonate. It is concluded that sodium bicarbonate inclusion at the rate of 1.50% of total ration increased cellulose digestibility, ciliate protozoal number, ruminal pH and total nitrogen concentration resulting in improved growth of lambs maintained on high concentrate diet. © 2002 Elsevier Science B.V. All rights reserved