Effects of addition of a liquid supplement supplying lactic acid bacteria to diets of alfalfa-concentrate and corn stover-concentrate in sheep

Abstract

To determine the effects of a liquid supplement containing lactic acid bacteria(SULIBAL) on rumen fermentation and utilization of mixed diets of alfalfa or corn stover and commercial concentrates, four adult male sheep (52 ± 10kg), fitted with rumen canulae, were fed four treatments composed of (%): T1 (alfalfa 55 and concentrate 45), T2 (alfalfa 50, concentrate 40 and SULIBAL 10), T3 (stover 55 and concentrate 45), T4 (stover 50, concentrate 40 and SULIBAL 10), with T1 and T3 serving as control to T2 and T4, respectively. The liquid supplement was formulated with diverse ingredients, most importantly fresh whey from cheese making and yogurt as sources of lactic acid bacteria. Rumen fermentation was characterized by measurement of pH, levels of NH3 and VFA, and kinetics of in situ DM disappearance; N balance in the body was also determined. Mean DM consumption (g/d) in T1 thru T4 was: 1148, 1291, 887, and 1023, with positive effects (P <0.05) of alfalfa and between T3 and T4, of SULIBAL. Rumen pH declined from initial values near 7.0 to levels of 5.7 to 5.8 at 8 h after ingestion began, then increased slowly up to 12h, without much effect of treatments. From initial levels of 43 to 51 mg NH3/L, ammonia concentration in rumen liquid climbed most rapidly post-prandially in T2 and T4, reached maxima (93 to 112 mg/L) at 4 h and thereafter decreased progressively until, at 12 h, reaching approximately initial levels in T1 and T2 and values below 30 mg/L in T2 and T4. Rumen concentration of total VFA showed principally an advantage of alfalfa over stover, while the molar percentage of propionic acid responded positively to the liquid supplement when this was combined with stover (T4). In situ DM degradation at 96 h of incubation surpassed 60% in all treatments, while estimated true DM digestibility favored the addition of SULIBAL (T2, 83.68; T4, 76.78=) over the controls (T1, 71.95; T3, 73.01). Nitrogen digestibility and retention were markedly higher in T1 and T2 (alfalfa) than T3 and T4 (stover), while between the latter two the presence of SULIBAL gave some improvement. It is concluded that addition of the liquid supplement to these diets proved to be beneficial, by tending to improve in vivo consumption and in situ estimated digestibility and possibly promoting the synthesis of microbial protein in the rumen (judging from the indirect evidence of formation and disappearance of NH3).