R. J. Wallace

Influence Of Aspergillus oryzae fermentation extract on the fermentation of a basal ration in the rumen simulation technique (Rusitec)

Frumholtz, P. P., Newbold, J., Wallace, R. J. (1989). Influence Of Aspergillus oryzae fermentation extract on the fermentation of a basal ration in the rumen simulation technique (Rusitec). Journal of Agricultural Science, 113 (2), 169-172.

Influence of foliage from different accessions of the sub-tropical leguminous tree, Sesbania sesban, on ruminal protozoa in Ethiopian and Scottish sheep

Abstract Nine different accessions of Sesbania sesban were examined for their toxicity to ciliate protozoa from sheep receiving a mixed grass hay–barley/fishmeal concentrate in Aberdeen, Scotland. Several accessions were much more toxic than those (ILRI 10865, ILRI 15036) identified and tested in a previous study. Two highly toxic accessions and one less toxic accession were compared with ILRI 15036 in a feeding trial in Debre Zeit, Ethiopia with sheep receiving a sululta hay–wheat bran diet. No suppression of protozoal numbers occurred in response to S. sesban supplementation (200xa0g/day). When rumen fluid removed from sheep on the supplemented diet was tested in vitro, protozoal activity appeared to be inhibited less by S. sesban in the mixed population than in either washed protozoa from the same rumen fluid or than had occurred in Scottish sheep. It was concluded that dietary, microbial or animal factors in the Ethiopian sheep had caused the destruction of the anti-protozoal material present in even the most potent accessions of S. sesban .

Influence of dietary rumen-degradable protein on bacterial growth in the rumen of sheep receiving different energy sources

An experiment with ruminally cannulated sheep was undertaken to determine how the dietary energy source affected the ability of rumen fermentation to respond to pre-formed amino acids compared to non-protein nitrogen in the diet. Four sheep received diets of grass hay (H) or molassed sugar beet pulp (BP) supplemented with 9.3 g N kg−1 DM added either as urea (U) or casein (C) in a 4 × 4 latin square with a factorial design. Measurements of rumen fermentation, microbial numbers and purine excretion were made in the third week of each 21-day period. Rumen total volatile fatty acids concentrations were higher with the BP diets (130 vs. 91 mM; P 0.05). A microbial response to rumen-degradable protein therefore occurred only with the more rapidly degraded BP diet, consistent with the idea that rumen microbial growth responds to pre-formed amino acids only when the energy source is fermented rapidly.

CHANGES IN THE MICROBIAL POPULATION OF A RUMEN-SIMULATING FERMENTER IN RESPONSE TO YEAST CULTURE

Yeast increased the total viable count of bacteria on a medium containing rumen fluid and soluble sugars by 38% (Pu2002 u20020.05). Microscopic counts indicated a 25% increase in total bacteria (Pu2002< 0.05). Bacterial counts with mannitol as sole energy source also increased (Pu2002< 0.05), indicating an increased Selenomonas population; that was not in itself sufficient to account for the increase in the total bacterial count. The protozoal population was significantly lower in yeast supplemented vessels (Pu2002< 0.001), which may account partly for the increased bacterial numbers. Key words: Yeast culture, probiotics, rumen bacteria, Rusitec

Influence of autoclaved or irradiated Aspergillus oryzae fermentation extract on fermentation in the rumen simulation technique (Rusitec)

Newbold, J., Brock, R., Wallace, R. J. (1991). Influence of autoclaved or irradiated Aspergillus oryzae fermentation extract on fermentation in the rumen simulation technique (Rusitec). Journal of Agricultural Science, 116 (1), 159-162.

Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation in heifers

Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation (PAP) were studied in a completely randomized experiment using 12 crossbred heifers (452 +/- 20 kg of BW). Treatments were control (CTR) or PAP. The acidosis induction protocol consisted of 3 periods: 3 mo of 100% fescue hay fed for ad libitum intake, 10 d (from d 1 to 10 of the experiment) of adaptation to the treatment (100% forage feeding + 10 mL/d of PAP top-dressed to the treatment group), and 5 d (from d 11 to 15 of the experiment) of transition, which consisted of increasing the concentrate (16.5% CP) 2.5 kg/d up to 12.5 kg/d while maintaining ad libitum intake of fescue and providing 10 mL/d of PAP to the treated heifers. Concentrate feeding of 12.5 kg/d was maintained until heifers developed acidosis (from d 16 to 22 of the experiment). When an animal was considered acidotic, it was changed to a 50:50 forage:concentrate diet, monitored for 4 d, and removed from the experiment. Samples of ruminal fluid were collected before and 6 h after feeding to determine pH, VFA, lactate, protozoa counts, and DNA extraction for quantitative real-time PCR and denaturing gradient gel electrophoresis analyses. Only samples collected during adaptation to the treatment, at 3 and 1 d before acidosis, on the acidosis day, and at 1 and 4 d after acidosis were analyzed. Differences were declared at P < 0.05. Heifers (83% for CTR, and 50% for PAP) entered into acidosis 5.25 +/- 0.17 d after the beginning of the transition. The fermentation profile of animals with acidosis was similar between treatments. From 3 d before acidosis to acidosis day, decreases in pH and in acetate-to-propionate ratio and increases in total VFA, butyrate, and entodiniomorph counts were observed. However, the greatest concentrations of Streptococcus bovis and Megasphaera elsdenii (79 +/- 54 and 104 +/- 73 ng of DNA/mL of ruminal fluid, respectively) and a decrease in DMI (10.6 vs. 6.46 kg, respectively) were recorded 1 d after acidosis. Compared with CTR heifers, heifers fed PAP had greater pH before feeding on d 6 (6.70 vs. 6.11), 8 (6.54 vs. 5.95), and 9 (7.26 vs. 6.59) after the beginning of the feeding challenge. Heifers fed PAP tended to have greater total VFA concentrations than CTR (124 and 114 +/- 4.0 mM, respectively). These results indicate that PAP may be effective in controlling acidosis of heifers during a rapid transition to a high-concentrate diet.

A comparison of methods for determining the concentration of extracellular peptides in rumen fluid of sheep.

Samples of rumen fluid were removed from pairs of sheep on four grass-hay-based diets 7 h after feeding. Micro-organisms were sedimented by centrifugation and the cell-free supernatant was treated with perchloric acid (PCA) to precipitate protein. The remaining fluid was analysed for peptides by several methods to determine how much peptide escaped degradation. Ammonia interfered with analysis by amino group reagents, especially ninhydrin. In this respect, o -phthalaldehyde and trinitrobenzene sulphonic acid were more specific and more useful than ninhydrin. Use of all these reagents showed that significant quantities of amino groups (equivalent to up to 153 mg amino acid N/1 of rumen fluid) were released by hydrolysis of the PCA extract with 6 M-HCI for 24 h. However, fluorescamine analysis indicated that the peptide content of the unhydrolysed PCA extract was

Influence of protease inhibitors on nitrogen distribution in ensiled perennial ryegrass and the utilisation of silage nitrogen for growth by rumen bacteria in vitro

Nsereko, V. L., Rooke, J. A., Newbold, C. J., Wallace, R. J. (1998). Influence of protease inhibitors on nitrogen distribution in ensiled perennial ryegrass and the utilisation of silage nitrogen for growth by rumen bacteria in vitro. Animal Feed Science and Technology, 76 (1-2), 51-63.

Influence of ionophores and energy inhibitors on peptide metabolism by rumen bacteria

Wallace, R. J., Newbold, J., McKain, N. (1990). Influence of ionophores and energy inhibitors on peptide metabolism by rumen bacteria. Journal of Agricultural Science, 115 (2), 285-290.

Influence of Aspergillus oryzae fermentation extract on rumen fermentation and blood constituents in sheep given diets of grass hay and barley

Aspergillus oryzae fermentation extract (AO; 2 g/day) was added to the diet of sheep fed grass hay supplemented with 30 or 70% barley. AO decreased the proportion of propionate in rumen volatile fatty acids with both levels of supplementation (146 and 163 mmol/mol with AO v . 157 and 186 mmol/mol with no addition for the low and high barley diets respectively; P v . 0·97 and 1·80 × 10 9 /ml respectively). Numbers of cellulolytic bacteria and ciliate protozoa were unchanged. Hay suspended in nylon bags in the rumen tended to be degraded more rapidly with AO, but the effect was not statistically significant. Neither barley nor AO significantly altered the plasma concentrations of glucose, urea, insulin, gastrin or cholecystokinin. It was concluded that the effects of AO were generally similar for both levels of barley supplementation and that changing the composition of the diet had no detectable effect on the measured indicators of nutritional status in blood.