Duodenal flow and digestibility in fauna-free sheep and in sheep monofaunated with Entodinium caudatum or Polyplastron multivesiculatum

Rumen fermentation and microbial population in lactating dairy cows receiving diets containing oilseeds rich in C-18 fatty acids

Sixteen Holstein rumen-cannulated primiparous milking dairy cows were fed a control diet (CN) based on maize silage and soyabean meal during a 4-week period before the start of a 21-d experiment with oilseeds containing high concentration of linoleic acid (Linola™) or linolenic acid (NuLin™). Thereafter, four cows received ad libitum one of each of four dietary treatments comprising of CN, Linola (LN), NuLin (NL) and LN/NL (50/50 % combination). Each LN, NL and LN/NL treatment contained 6 % oil of DM. Rumen digesta samples were collected on days 6, 11, 16 and 21 and milk samples on days 13, 15 and 17. There were no effects (P>0.05) of the oilseeds on pH and concentrations of NH3-N and total volatile fatty acids, while the acetate:propionate ratio was decreased (P< 0.05). The oilseeds also decreased (P< 0.05) protozoa and increased (P< 0.1) total cellulolytic bacteria in rumen fluid, especially when containing high dietary linoleic acid (P< 0.05). The milk protein concentration was increased (P< 0.1) by the dietary linoleic acid, which produced most beneficial results. It was concluded that supplements of linoleic acid in diets of ruminants might contribute to better digestion of dietary fibre and increased quality of milk.

Effect of the rumen ciliates Entodinium caudatum, Epidinium ecaudatum and Eudiplodinium maggii, and combinations thereof, on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 x 2 x 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH4-to-CO2 ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.

Effect of rumen protozoa on Escherichia coli O157:H7 in the rumen and feces of specifically faunated sheep

The effects of rumen protozoal populations on ruminal populations and fecal shedding of Escherichia coli O157:H7 were evaluated by using specifically faunated sheep. Nine fauna-free sheep (three animals per treatment) were inoculated with Dasytricha spp. (DAS sheep); with mixed population A (PopA) comprising Entodinium spp., Isotricha spp., Diplodinium spp., and Polyplastron spp.; or with mixed population B (PopB) comprising Entodinium spp., Isotricha spp., Dasytricha spp., and Epidinium spp.; six sheep were maintained fauna-free (FF sheep) to serve as controls. Sheep were fed barley silage-based diets, and treatment groups were housed in isolated rooms. Sheep were inoculated orally with 10(10) CFU of a four-strain mixture of nalidixic acid-resistant E. coli O157:H7. Samples of ruminal fluid and feces were collected over 77 days. Polyplastron spp. were detected in only one sheep in PopA, and Dasytricha spp. were detected only once within the PopB cohort. Sheep in the DAS group were 2.03 times more likely (P < 0.001) to shed E. coli O157:H7 than were those in the other three treatments, whereas the PopB sheep were less likely (0.65; P < 0.05) to shed this bacterium. The likelihood of harboring ruminal E. coli O157:H7 also tended (P = 0.06) to be higher in DAS and was lower (P < 0.01) in FF than in other cohorts. Possibly, Dasytricha spp. had a hosting effect, and Epidinium spp. had a predatory relationship, with E. coli O157:H7. Additional study into predator-prey and hosting relationships among rumen protozoa and E. coli O157:H7 is warranted.

Comparison of duodenal flow and digestibility in fauna-free sheep inoculated with Holotrich protozoa, Entodinium monofauna or total mixed protozoa population

The present results are the last part of a series of experiments conducted in this laboratory on metabolism of major individual rumen ciliate protozoa species and their combinations in sheep. These species were inoculated into the rumen of fauna-free (FF) sheep to study digestibility of dietary fibre and duodenal flow of N. Sixteen rumen- and duodenum-cannulated FF sheep were divided into four equal groups and used in the present experiment. One group remained FF, while the other three were each inoculated intraruminally with the Holotrich protozoa sp. (HT), Entodinium sp. (EN) or total mixed fauna (TF). In comparison with the FF group, the HT did not affect (P>0.05) the duodenal flow of non-NH3-N and bacterial-N, while the flow was decreased (P < 0.05) by both the EN and TF populations. The digestibility of fibre was increased (P < 0.05) by both the EN and TF populations, but the results for the HT group were mostly similar to those for the FF sheep. The fibre digestibility in the stomach for TF was intermediate between that for EN and FF. It was concluded that except when fed high-carbohydrate diets, the presence in the rumen of the HT protozoa are of no significant value or major detriment to ruminant production.

The effect of absence of protozoa on rumen biohydrogenation and the fatty acid composition of lamb muscle

The effects of the absence of protozoa in the rumen of lambs on animal growth, rumen fermentation, microbial diversity and fatty acid profiles in abomasal fluid and intramuscular fat were measured in ten control and ten protozoa-free (PF) lambs. PF lambs were prepared by isolating them from ewes within the first 24 h after birth. The PF and control lambs were kept for 4 months in two different fields and received a daily supplement of 250 g concentrate. The bacterial populations visualised by denaturing gradient gel electrophoresis differed between the two groups of animals and showed a higher bacterial diversity in control lambs than in PF lambs. Abomasal contents from control lambs contained higher concentrations of 22 : 5n-3 and 22 : 6n-3 and lower concentrations of vaccenic acid (trans-11–18 : 1) and 20 : 3n-6 than PF lambs. The rest of the fatty acids, including the conjugated linoleic acid (CLA) isomers, were present at the same concentrations in abomasal contents from both experimental groups. Fatty acid composition in intramuscular fat showed differences between the groups. PF lambs had higher proportions of 18 : 0, 18 : 3,trans-10,cis-12-CLA and total SFA than control lambs. Control lambs had higher proportions ofcis-9–18 : 1,cis-9,cis-12–18 : 2, 20 : 3n-6, 22 : 6n-3 (DHA) and MUFA. In conclusion, rumen defaunation led to higher tissue levels of thetrans-10,cis-12-CLA isomer and SFA and lower PUFA:SFA ratio andn-3 PUFA in lamb muscle.

Effect of dietary Enterolobium cyclocarpum on microbial protein flow and nutrient digestibility in sheep maintained fauna-free, with total mixed fauna or with Entodinium caudatum monofauna

Three groups of five wethers with ruminal and duodenal cannulas and maintained as either fauna-free (FF) or inoculated with total mixed fauna (TF) or Entodinium caudatum as a single-species monofauna (EN) were used in an experiment with two 28 d periods. In the first period, the sheep were fed a control barley-based diet (40:60 concentrate to silage DM) and in the second period the diet was supplemented with 187 g DM of Enterolobium cyclocarpum for the last 12 d of the period. The diets of period 1 and 2 were isonitrogenous. There was no effect of fauna on apparent ruminal and total tract organic matter and fibre digestion, but bacterial and microbial N flow and efficiency were improved in FF sheep compared to TF sheep. In period 2, protozoal numbers were reduced between 31 and 88 % 2 h after feeding E. cyclocarpum for the third to twelfth day of supplementation and by an average of 25 % in samples collected over the 24 h feeding cycle. Supplementation of the diet with E. cyclocarpum and the consequent protozoal reduction in TF and EN sheep improved the flow of non-ammonia N and bacterial N to the small intestine and the efficiency of microbial synthesis. However, E. cyclocarpum reduced ruminal organic matter digestion, especially in faunated sheep, and total tract organic matter, N and fibre digestion. Thus, a reduction in the protozoal cell numbers of 25 % was sufficient to achieve the beneficial effects of reduced fauna on the bacterial protein supply, but diet digestibility was reduced.