Fermentation characteristics and ruminal ciliate protozoal populations in cattle fed medium- or high-concentrate barley-based diets.

Abstract

Fermentation characteristics were measured and numbers and distribution by genera of ciliate protozoa were determined in ruminal fluid samples collected from 10 ruminally cannulated steers during the first 30 d of their being fed barley-based diets containing 62% (Medium Barley) or 95% (High Barley) barley grain (DM basis). Ruminal samples were collected at 5-d intervals over the 30-d periods beginning after adaptation (i.e., at the first full feeding of each diet). Ruminal pH and ammonia concentrations were lower (P < 0.001) with the High Barley than with the Medium Barley diet. Concentrations of total VFA and propionate and amylase activity of ruminal fluid were higher (P < 0.001) on High Barley than on Medium Barley. Total protozoal numbers in ruminal fluid were 42% lower (P < 0.05) on High Barley (470 x 10(3)/mL) than on Medium Barley (804 x 10(3)/mL). On Medium and High Barley diets, respectively, Entodinium spp. made up 89 and 91% of the ciliate protozoal populations. With the Medium Barley diet, relative proportions of Dasytricha, Ophryoscolex, Ostracodinium, Diplodinium, and Metadinium spp. in the total ciliate population were 4.5, 0.4, 0.5, 0.7, and 0.3%, respectively. When the High Barley diet was fed, these genera were not detected. In a subsequent survey, ruminal samples were collected from 200 finishing cattle at slaughter. Average protozoal population was 328 x 10(3)/mL, and Entodinium spp. constituted 97% of the total. These data demonstrate that a large population of Entodinium spp. can persist in the rumen of cattle fed high barley grain-based finishing diets.

The role of pH on the survival of rumen protozoa in steers

“…Veira et al (1983) observed a less abrupt decrease in rumen pH in faunated sheep compared to ciliate free animals. Because starch granules are engulfed by protozoa, especially on high concentrated diets, starch degradation is slower (Hristov et al, 2001), resulting in less production of organic acids in the rumen of faunated steers (Santra & Karim, 2002;Santra et al, 2007). The stabilization effect of rumen pH attributed to rumen ciliates appears to have a significant effect on bacterial growth and enzyme activity since they can be inhibited at low pH values (Williams & Coleman, 1992).…”

In vitro methane formation and carbohydrate fermentation by rumen microbes as influenced by selected rumen ciliate species

“…As the composition of the protozoal fauna is known to differ between diets (Hristov et al 2001;Tymensen et al 2012), inconsistent effects of defaunation between studies might result from differences in the fermentative activity of individual ciliate species. There are indications from studies performed in vitro (Jouany and Toillon 1997;Ranilla et al 2007) and in vivo (Jouany et al 1981) that individual ciliate species affect methane (CH 4 ) formation differently.…”

Effect of Replacement of Soybean meal by Dried Tomato Pomace on Rumen Fermentation and Nitrogen Metabolism in Beef Cattle

“…For the analysis of NH 3 -N, 10 mL of 50% H 2 SO 4 solution was added to 100 mL of ruminal fluid. The mixture was centrifuged at 16,000×g for 15 minutes and the supernatant was stored at -20°C prior to NH 3 -N measurement (Hristov et al, 2000). Volatile fatty acids were analyzed by HPLC (model RF-10AXmugiL, Shimadzu, Japan) according to Zinn and Owens (1986).…”