No 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.

Six wethers, each fitted with a rumen cannula and duodenal reentrant cannula, were used to study effects of ciliate protozoa on rumen digestion and metabolism. A corn: corn silage (1:1) diet was fed for two periods. During the first period, defaunation was attempted with nonyl phenol ethylene oxide. Defaunation was complete in three sheep and partial in the other three sheep in which a reduced population of a small Entodinium sp. was observed. During the second period the sheep were inoculated with ciliate protozoa, which established a large population in all animals. Apparent digestion in the stomach of organic matter and starch was higher when a large protozoal population was present. Amino acid flow through the duodenum was greater in defaunated animals. A large population of ciliates was associated with increases in both rumen ammonia and plasma urea but had a stabilizing effect on ruminal pH. Volatile fatty acids were higher in the defaunation period, but there were only small differences of molar proportions of the acids between the two periods. Effects of ciliate protozoa are related to animal performance.

The objective of this study was to investigate the effects of sodium salts of individual fatty acids on protozoal numbers and ruminal fermentation variables in vitro. Ruminal inoculum was obtained from two heifers fed a finishing diet consisting of (DM basis) 90% rolled barley grain, 4% barley silage, 5% soybean meal, and 1% mineralized salt. Fatty acids (FA) were included individually in the inoculum as follows: C6:0, C8:0, and C10:0 at concentrations (wt/vol) of 0.0625, 0.125, and 0.25%; C14:0 and C18:0 at concentrations of 0.125, 0.25, and 0.5%; and C12:0, C16:0, C18:1, C18:2, and C18:3 at concentrations of 0.25, 0.5, and 1.0%. 15N-Labeled casein was included as a N tracer. In the presence of medium-chain saturated FA (particularly C10:0 and C12:0), no ciliate protozoa (99.8%Entodinium spp.) were recovered from the incubation medium. Long-chain unsaturated FA (C18:3, C18:2, C18:1) also decreased (P < 0.05) protozoal numbers. At all concentrations tested, C10:0 and C12:0 decreased (P < 0.05) ammonia and total VFA concentrations (by 29 and 22%, respectively) and increased (P < 0.05) concentrations of total free amino acids, reducing sugars, and soluble protein. At the greatest concentrations of these FA, xylanase and amylase activities of the incubation media were decreased (P < 0.05). The C18 unsaturated FA increased (P < 0.05) the polysaccharide-degrading activities of the media. These in vitro results suggest that long-chain unsaturated FA in combination with medium-chain saturated acids have the potential to decrease protozoal numbers and ruminal ammonia utilization in cattle fed high-grain diets.

The objective was to measure rumen fermentation and duodenal flow of amino acids and nonammonia N components in five groups of five ruminally and duodenally cannulated wethers that were fauna-free, or inoculated with the ciliate protozoa genera of Isotricha, Dasytricha, Entodinium, or a normal population (total) of fauna. They were used in two 25-d periods and fed a haycrop-based diet in the first period and a corn silage-based diet in the second period. Feces, duodenal digesta, and rumen contents were sampled in each period and analyzed. The number of Entodinium in wethers containing the Entodinium monofauna was higher than the total protozoa numbers, including Entodinium, in wethers containing total fauna population. The type of diet or fauna did not affect total volatile fatty acid concentrations in rumen fluid. The ammonia N concentration in rumen fluid was higher in wethers containing total fauna (25 mg/100 ml) than in fauna-free wethers fed the two diets (18 and 12 mg/ 100 ml). In comparison with the respective fauna-free wethers, the concentration of ammonia in wethers containing Entodinium was higher when fed the corn silage diet, but not different when fed the haycrop diet. Ruminal presence of total fauna or Entodinium decreased the nonammonia N by 16 and 17%, and total amino acid flows from the stomach by 20 and 19%, respectively. Flow of bacteria N was decreased in wethers fed the two diets when Entodinium or total fauna were present in the rumen. The presence of Isotricha resulted in higher flow of bacteria N in wethers fed the haycrop diet, but the presence of Dasytricha resulted in higher bacteria N flow in wethers fed the corn silage diet. Entodinium was the most detrimental of ciliate protozoa species concerning protein nutrition of the host ruminant.

The value of sunflower seed (SS) in finishing diets was assessed in two feeding trials. In Exp. 1, 60 yearling steers (479 +/- 45 kg) were fed five diets (n = 12). A basal diet (DM basis) of 84.5% steam-rolled barley, 9% barley silage, and 6.5% supplement was fed as is (control), with all the silage replaced (DM basis) with rolled SS, or with grain:silage mix replaced with 9% whole SS, 14% whole SS, or 14% rolled SS. Liver, diaphragm, and brisket samples were obtained from each carcass. In Exp. 2, 120 yearling steers (354 +/- 25 kg) were fed corn- or barley-based diets containing no SS, high-linoleic acid SS, or high-oleic acid SS (a 2 x 3 factorial arrangement, n = 20). Whole SS was included at 10.8% in the corn-based and 14% in the barley-based diets (DM basis). In Exp. 1, feeding whole SS linearly increased DMI (P = 0.02), ADG (P = 0.01), and G:F (P = 0.01). Regression of ME against level of whole SS indicated that SS contained 4.4 to 5.9 Mcal ME/kg. Substituting whole for rolled SS did not significantly alter DMI, ADG, or G:F (8.55 vs. 8.30 kg/d; 1.36 vs. 1.31 kg; and 0.157 vs. 0.158, respectively). Replacing the silage with rolled SS had no effect on DMI (P = 0.91) but marginally enhanced ADG (P = 0.10) and improved G:F (P = 0.01). Dressing percent increased linearly (P = 0.08) with level of SS in the diet. Feeding SS decreased (P < 0.05) levels of 16:0 and 18:3 in both diaphragm and subcutaneous fats, and increased (P = 0.05) the prevalence of 18:1, 18:2, cis-9,trans-11-CLA and trans-10,cis-12-CLA in subcutaneous fat. In Exp. 2, barley diets supplemented with high-linoleic SS decreased DMI (P = 0.02) and ADG (P = 0.007) by steers throughout the trial, whereas no decrease was noted with corn (interaction P = 0.06 for DMI and P = 0.01 for ADG). With barley, high-linoleic SS decreased final live weight (554 vs. 592 kg; P = 0.01), carcass weight (329 vs. 346 kg; P = 0.06), and dressing percent (58.5 vs. 59.4%; P = 0.04). Steers fed high-linoleic SS plus barley had less (P < 0.05) backfat than those fed other SS diets. No adverse effects of SS on liver abscess incidence or meat quality were detected. Although they provide protein and fiber useful in formulating finishing diets for cattle, and did improve performance in Exp. 1, no benefit from substituting SS for grain and roughage was detected in Exp. 2. Because of unexplained inconsistencies between the two experiments, additional research is warranted to confirm the feeding value of SS in diets for feedlot cattle.

No abstract

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 (Linolae) or linolenic acid (NuLine). 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 NH 3 -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. Key words: Dairy cows: Linoleic acid: Linolenic acid: Rumen fermentation: Rumen microbial populationThe negative effects of the presence of ciliate protozoal species in the rumen on the efficiency of the ruminal microbial synthesis of protein and on the duodenal flow of non-NH 3 -N components are well established (1 -4) . These effects result in the lower dietary N utilisation by ruminants (5,6) and increase the dietary protein requirement by about 30 % (7) . As ciliate protozoa are not considered by many to be essential for the well being of the host ruminant, numerous chemical and physical methods have been applied experimentally over the last few decades to eliminate ciliate protozoa from the rumen (defaunation), but none of the methods was practical for use in ruminant production (8,9) . Also, a fauna-free sheep flock was established by a protozoa-free breeding programme (10,11) and maintained with normal growth and without protozoa re-infection for several generations (over 20 years).The dietary lipids, including C-18 fatty acids, are toxic to rumen ciliate protozoa (12 -14) and may result in either a total elimination (defaunation) or in a significant reduction of the rumen protozoal population (reduced fauna) (15) . Because the large vestibuliferid and cellulolytic protozoal species are highly susceptible to lipids, more than the small protozoal species, reduced fauna usually contains only Entodinium sp. (15) . All, fauna-free, defaunation and reduced fauna contribute to increased efficiency of the ruminal microbial synthesis of protein (4,16 -18) . Decreased protozoa numbers due to dietary lipids have been reported earlier in several studies (19) . But, dietary lipids can also reduce the rumen population of cellulolytic bacteria (20) , especially due to their content of mid-...