Performance, intestinal microflora, and wall morphology of weanling pigs fed sodium butyrate

Adding organic acids to piglet diets is known to be helpful in overcoming postweaning syndrome, and butyric acid is known to be the main energy source for the epithelial cells of the large intestine and the terminal ileum. This study investigated the effect of sodium butyrate (SB) on in vitro and in vivo swine microflora, piglet growth performance, and intestinal wall morphology. During a 24-h in vitro cecal fermentation, total gas production and maximal rate of gas production were reduced linearly by SB (P < 0.001). Ammonia in cecal liquor was increased linearly by SB after 4, 8, and 24 h of fermentation (P < 0.001). In the in vivo study, 48 piglets housed in individual crates were allotted to 4 treatment groups (12 animals per treatment) for 6 wk. Piglets received a basal diet with a) no addition (control), or with SB at b) 1,000 ppm, c) 2,000 ppm, or d) 4,000 ppm. After 6 wk, 6 animals per treatment were killed, and samples of intestinal content and mucosa were collected. Sodium butyrate did not improve the animal growth performance. In the cecum, SB increased pH and isobutyric acid concentration (linear, P < 0.05) and tended to increase ammonia concentration (P = 0.056). Intestinal counts of clostridia, enterobacteriaceae, and lactic acid bacteria as well as intestinal mucosal morphology were not affected by feeding SB. This study showed that SB influenced the cecal microflora in an in vitro system, reducing the total gas production but increasing ammonia concentrations. When fed to piglets, SB did not improve the animal growth performance, increased cecal pH, and tended to increase cecal ammonia concentrations. Further studies will be needed to better understand the mechanisms underlying the effects observed when SB is fed to piglets.     

高精料日粮对山羊瘤胃和盲肠发酵及生物胺生成与吸收的影响研究

本实验旨在探究饲喂高精料日粮对山羊瘤胃和盲肠发酵、生物胺生成与吸收的影响研究。试验选用6头装有永久性瘤胃瘘管的雄性波杂山羊,随机分成低精料组与高精料组,实验期24 d。结果显示,与低精料组相比,饲喂高精料日粮的山羊瘤胃液中总挥发性脂肪酸、乙酸、丙酸、丁酸、戊酸、总支链脂肪酸、酪胺、腐胺、组胺、甲胺和色胺浓度显著性增加(P<0.05),而瘤胃pH和乙丙比显著降低(P<0.05);饲喂高精料日粮的山羊盲肠内容物中的乙酸、丙酸、总挥发性脂肪酸浓度和上述5种生物胺浓度显著增加(P<0.05);同时,瘤胃和盲肠静脉血中的上述5种生物胺的浓度显著提高(P<0.05)。相关性分析结果表明,瘤胃液中酪胺、腐胺、甲胺和色胺浓度与瘤胃静脉血所对应的生物胺浓度呈显著正相关(P<0.05),且盲肠内容物中酪胺、腐胺、甲胺和色胺与盲肠静脉血中对应的生物胺的浓度呈显著正相关(P<0.05)。结果说明,饲喂高精料日粮促进了山羊瘤胃和盲肠发酵,提高了瘤胃与盲肠内容物中生物胺浓度,暗示高精料日粮可能提高消化道上皮的通透性,促进消化道上皮对生物胺的吸收。     

Impact of lactic acid fermentation in the large intestine on acute lactic acidosis in cattle

Microbial and fermentation changes in the ingesta of the large intestine and their influence on the pathogenesis of acute lactic acidosis were studied in 4 cows fitted with permanent cannulas in the ileum and cecum. Feed mixture containing 65% of maize was infused into the cecum for several days in amounts of 2 and 4 kg per day. The daily amount was divided in 8 equal portions and given with 3 l of warm physiologic saline solution. During the period of ad libitum feeding of hay, the pH values in cecal digesta were 7.4 to 7.6 and the amount of total volatile fatty acids 40-60 mmol/kg with high molar percentage (87-90 mol%) of acetic acid. As to lactic acid only the L(+) lactic isomer was found in a concentration of about 0.4 mmol/kg. Infusion of low amounts of starch induced mild lactic acid fermentation in the cecum associated with a pronounced increase in the concentration of L(+) and D (-) lactic acid to peak levels of 80 +/- 10 mmol/kg and 7 +/- 1 mmol/kg, respectively. Lactic acid fermentation ceased within 2 to 3 days indicating that the gut microflora had adapted to the starch infusion. Slight decreases of blood pH and bicarbonates in blood as well as a moderate increase of netto acid-base excretion in urine indicated mild changes of acid-base balance, but clinically no pathological symptoms were observed. Higher amounts of infused starch caused pronounced lactic acid production in the large intestine which persisted throughout the experiment. Peak L(+) and D(-) lactic acid concentration in cecal digesta reached on the average 137 +/- 16 mmol/kg and 45 +/- 7 mmol/kg respectively. Significant decreases of blood pH values from 7.41 +/- 0.02 to 7.18 +/- 0.08 (P < 0.001), actual bicarbonate from 28.2 +/- 3.2 to 11.0 +/- 2.6 mmol/l (P < 0.001) and base excess from 3.9 +/- 3.6 to -15.2 +/- 3.8 mmol/l (P < 0.001) were observed. D (-) lactic acid concentration in blood increased to 3.2 +/- 0.4 mmol/l, but L(+) lactic acid values remained unchanged under 1 mmol/l. Clear clinical symptoms of indigestion and intoxication characterized by severe inappetence, ruminal stasis and general weakness were also observed. Typical clinical symptoms of disease as well as blood and urine changes in acid-base balance indicated that lactic acid fermentation in the large intestine contributes considerably to the pathogenesis of acute ruminant lactic acidosis.     

Effect of live yeast culture supplementation on apparent digestibility and rate of passage in horses fed a high-fiber or high-starch diet

Eight crossbred male horses aged 12 +/- 5 yr and with BW of 305 +/- 18 kg were used in pairs in a 4 x 4 Latin square design with 4 ground and pelleted diets. Each pair included a cecum and right ventral colon-fistulated animal and a cecal-fistulated animal. The 4 horse diets were a high-fiber diet (HF+0) based on dehydrated alfalfa, a high-starch diet based on barley and wheat bran (HS+0), and the HF or HS diets supplemented with Saccharomyces cerevisiae (SC) CBS 493.94 (HF+SC and HS+SC). The probiotic preparation contained 4.5 x 10(9) cfu/g of live yeast mixed with the culture medium, and was top-dressed onto the feed pellets at a rate of 10 g/d, equally distributed between the 2 daily meals. All 4 diets were offered in the same quantities (18.0 g of pelleted feed DM + 3.5 g of long wheat straw/kg of BW per d). Each of the 4 experimental treatments was divided into a 21-d period of diet adaptation followed by a 10-d period of total fecal collection for digesta flow rate and apparent digestibility measurements. Three markers were used to measure mean retention time (MRT) of the feed particles: Yb bound to the pelleted feeds for MRT in the whole digestive tract (MRT(Yb)), Eu bound to the pelleted feeds, and Dy bound to the fecal particles for MRT in the hindgut (MRT(Eu) and MRT(Dy)). Apparent digestibilities of DM, OM, and CP were greater (P < 0.001) in the HS than HF diet, independently of SC supplementation, whereas ADF digestibility was greatest in the HF diet (P = 0.035). Cellulolytic activity estimated through the in vitro disappearance rate of the dietary ADF fraction (IVAD(ADF)) was less (P < 0.001) in the HS than the HF diet. There was no dietary effect on NDF digestibility due to the longer MRT(Eu) of small particles in the hindgut (P = 0.036), which compensated for the lower fibrolytic activity expressed per unit of time in the HS compared with the HF diet. Supplementation with SC improved ADF digestibility (P = 0.038) and stimulated DM (P = 0.030) and NDF (P = 0.038) intakes, but had no effect on the MRT of solid digesta. The absence of any significant diet x SC interaction supports the strategy of using SC to stimulate cellulose digestion and improve the nutritional status of horses under both HF and HS diets.     

Feeding and microbial disorders in horses: 1-effects of an abrupt incorporation of two levels of barley in a hay diet on microbial profile and activities

Cecal and colonic fluid samples collected from three ponies were analyzed to determine the effects of an abrupt incorporation of barley in a hay diet on their microbial and biochemical characteristics. Three diets based on meadow hay and rolled barley were tested in a 3×3 Latin square experiment: 100% hay (100:0, 114 gDM/KgBW^0.75/day), 70% hay—30% barley (70:30, 69gDM/KgBW^0.75/day) and 50% hay—50% barley (50:50, 58gDM/KgBW^0.75/day). Enumeration of total anaerobic and aeroanaerobic bacteria, lactate-utilizing and cellulolytic bacteria, lactobacilli and streptococci, as well as pH, lactate and VFA concentrations, were determined before and five hours and 29 hours after the abrupt incorporation of barley in the hay diet. Whatever the amount of barley incorporated, an increase of total anaerobic bacteria, lactobacilli and streptococci, in the cecum and in the colon, was reported 29 hours after the changing of diet. Lactateutilizing and cellulolytic bacteria were not significantly modified five hours and 29 hours after the ingestion of a new diet. However a decrease of [(acetate+butyrate)/propionate] ratio was registered while lactate concentration increased although pH remained fairly constant through the changing of diet. The colon appeared to be the main site affected by the abrupt incorporation of readily fermentable carbohydrates in the diet. Thus, this section of the digestive tract needs further exploration to establish the linkage between the changes of the ecosystem as reported here, and the apparition of intestinal disorders.     

Tributyrin and lactitol synergistically enhanced the trophic status of the intestinal mucosa and reduced histamine levels in the gut of nursery pigs

This study determined whether tributyrin and lactitol could synergistically facilitate the transition from milk to solid feed in nursery pigs. At 21 d after birth, 64 piglets were moved from the piggery to a production barn and fed a medicated diet. At 28 d after birth, the piglets were weighed and allotted into four groups and fed a standard nonmedicated diet (control) or the control diet with tributyrin (butanoic acid 1,2,3-propanetriyl ester; 10 g/kg), or with lactitol (beta-D-galactopyranosyl-(1-->4)-D-sorbitol; 3 g/kg), or with tributyrin (10 g/kg) plus lactitol (3 g/kg). On d 0, 14, and 42 after being fed the control or experimental diets, the animals were weighed, and animal health, feed intake, and feed conversion ratio were determined. On d 42, four piglets from each treatment were killed to measure the empty and full weight of the gut, as well as the weights of the liver and kidneys. The jejunum and cecum were sampled to analyze the luminal concentrations of lactic acid; short-chain fatty acids; and mono-, di-, and polyamines and to assess the mucosal status. Mortality after 42 d ranged from 19% for animals fed the control diet, to 6% for animals fed the tributyrin or lactitol diets, and to 0% for animals fed the tributyrin+lactitol diet. After 14 d, the ADG was 127% greater (P < 0.05) in animals fed the tributyrin+lactitol diet than in animals fed the control or tributyrin diets. After 42 d, animals fed the tributyrin+lactitol diet were heavier (P < 0.05) than animals fed the tributyrin diet. At slaughter, no differences (P > 0.05) in organ weights were observed. With the exception of animals fed the lactitol diet, wherein cecal lactic acid levels increased threefold (P < 0.01), the luminal concentrations of lactic acid and short-chain fatty acids were not different (P > 0.05). Among the various amines analyzed, the only response (P < 0.05) was a 66 and 49% decrease in histamine levels in the jejunum and cecum, respectively, in animals fed the tributyrin+lactitol diet compared to the control diet. In the jejunum of animals fed the lactitol or tributyrin+lactitol diets, the length of the villi was increased by 12% (P < 0.05) compared to animals fed the control diet, whereas the tributyrin diet did not have any effect on the villi (P > 0.05). In the cecum, the depths of the crypts were reduced (P < 0.001) by 18% in animals fed the lactitol diet and 45% in animals fed the tributyrin or tributyrin+lactitol diets compared to animals fed the control diet. In conclusion, a diet containing tributyrin and lactitol as nutribiotics resulted in lower histamine levels in the jejunum and cecum, as well as longer jejunal villi and shallower cecal crypts.     

生长育肥猪后肠纤维分解菌的数量及微生物发酵作用

本试验采用严格厌氧微生物学方法 ,对生长肥育猪的盲肠、结肠和直肠内容物中总厌氧菌和纤维分解菌的数量、纤维素酶活性、氨态氮和VFA含量进行了测定。结果表明 ,盲肠和直肠内容物中纤维分解菌的数量显著高于结肠(P<0.01) ;盲肠内容物中羧甲基纤维素酶活性最高 ,其次是结肠 ,直肠最低(P<0.05) ;直肠和盲肠的氨态氮浓度显著高于结肠(P<0.05) ;盲肠、结肠和直肠的总VFA含量分别为82.79、154.47和143.80mmol/L ;乙酸的摩尔百分比为盲肠>结肠>直肠 ;丙酸的摩尔百分比无明显改变 ;丁酸的摩尔百分比为盲肠<结肠<直肠(P>0.05)。本试验证明 ,饲喂玉米—豆粕型日粮的生长肥育猪后肠中存在相当数量的纤维分解菌 ,盲肠、结肠和直肠内容物中纤维分解菌的数量分别占可培养微生物区系的8.6 %、3.1 %和22.1 %。后肠微生物发酵类型为乙酸发酵型。     

Isolated canine and murine intestinal cells exhibit a different pattern of fuel utilization for oxidative metabolism

The amount and type of dietary fiber influences the end-products of fermentation and thus fuel availability to intestinal tissue. Metabolic fuel usage was studied in intestinal cells isolated from dogs consuming a commercial diet or from rats consuming either a commercial rat diet or dog diet to examine preferential fuel usage, the effect of diet, and species differences. Production of 14CO2 was measured by incubating cells in media containing either D-[U-14C]glucose, [1-14C]n-butyrate, L-[U-14C]glutamine, or [1-14C]propionate with or without competing substrates. The presence of a mixture of 5 mM each of glucose, butyrate, propionate, and acetate and 1 mM glutamine in the media decreased CO2 production from glucose, glutamine, and propionate by canine enterocytes (P < 0.05) and from glutamine and propionate by canine colonocytes (P < 0.05). The presence of glutamine in the media decreased glucose oxidation by murine enterocytes, regardless of the diet. Similarly, glutamine decreased glucose oxidation by murine colonocytes (P < 0.05), but only when the rats had consumed the rat diet. Regardless of diet, murine colonocytes oxidized more butyrate (P < 0.01) than did enterocytes, and murine enterocytes tended (P < 0.07) to oxidize more glucose than did colonocytes. The proportion of propionate in colonic contents was higher in dogs than in rats (P < 0.02), and the proportion of butyrate tended to be higher in contents from rats than in those from dogs (P < 0.08). Colonic and cecal wet weights were decreased (P < 0.05) when rats were fed the commercial dog diet. Preferred utilization of substrates by isolated canine enterocytes and colonocytes differed from that of murine intestinal cells. These differences were only partially overcome by feeding the same diet to each species.     

Effect of levels of starch,fiber, and lactose on digestion and growth performance of early-weaned rabbits

The effect of source of carbohydrate on gut histology, digestion efficiency, and growth performance in early-weaned (25 d) rabbits at the starter period (25 to 39 d) was investigated. Six diets were factorially arranged to study the effect of partial substitution of starch (0, 25, or 50%) by lactose at two levels of fiber (30 or 36% NDF). Diets were formulated to meet or exceed essential nutrient requirements of growing rabbits. A feeding trial was conducted to measure the effect of treatments on growth performance in 252 rabbits that were fed the experimental diets in the starter period and thereafter received a common feed until 60 d of age. Fecal apparent digestibility was determined at 35 d of age in nine animals per diet. The four diets with extreme lactose content were used to determine ileal apparent digestibility of starch and lactose (nine replicates per diet), weights of stomach and cecum, stomach pH, cecal fermentation traits, amylase and disaccharidase activities (10 animals per diet), and jejunal morphology (six animals per diet). Weaning increased (P < 0.001) amylase activity by 59% but decreased (P < 0.001) maltase, sucrase, and lactase activities by 30, 48, and 72%, in parallel with a reduction of villus height by 19%. Dietary NDF level did not affect either jejunal morphology or sucrase and lactase activities but increased amylase (P = 0.05) and maltase (P < 0.001) activities by 22 and 92%, respectively. Substitution of starch by lactose had no effect on jejunal morphology or enzymatic activity. Ileal lactose and starch digestibility were not affected by dietary NDF or lactose level and averaged 73.8 and 90.8%, respectively. Substitution of starch by fiber and lactose affected ileal flux of starch plus lactose (by -0.5 and +1.7 g/d) and cecal pH (by +2.1 and -2.8%, respectively). Fecal NDF digestibility was relatively low (23.1% on average) and was not affected by treatments, whereas that of lactose and starch was almost complete. An increase of dietary NDF level led to an impairment of ADG and feed efficiency in the starter (P < 0.002) and in the overall (P < 0.03) fattening period. Substitution of starch by lactose linearly decreased (P < 0.001) feed efficiency in the starter period and linearly increased (P < 0.001) diarrhea incidence in the fattening period. The results indicate that digestive capability of early-weaned rabbits is limited and should be taken into account to establish optimal levels and sources of carbohydrates in the starter diet.     

Effects of direct-fed microbial supplementation on digestibility and fermentation end-products in horses fed low- and high-starch concentrates

A study was conducted to determine whether direct-fed microbials (DFM) could be used to increase digestibility and minimize the risk of acidosis associated with feeding an increase in the amount of starch fed to horses. Fifteen mature Thoroughbred geldings were randomly assigned to 1 of 3 treatments in a 3 x 3 Latin square design balanced for carryover effects. Within each 26-d period, horses were offered grass hay + low-starch concentrate (LS; 1.2 g of starch x kg of BW(-1) x meal(-1)) from d 1 to 13 and then were abruptly changed to hay + high-starch concentrate (HS; 2.4 g of starch.kg of BW(-1)x meal(-1)) on d 14 continuing through d 26. The DFM treatments were offered in concentrate pellets at a target dosage of 10(8) cfu/(50 kg of BW x d) as follows: no DFM (CON; control), Lactobacillus acidophilus (LAC1; single-species DFM), or a mixture of L. acidophilus, Lactobacillus casei, Bifidobacterium bifidum, and Enterococcus faecium (LAC4; multiple-species DFM). Total feces were collected over 72 h from d 11 to 13 (LS; low dietary starch collection), from d 15 to 17 (AC; abrupt change in dietary starch collection), and at the end of each experimental period, from d 24 to 26 (HS; high dietary starch collection). Data collected consisted of total DM intake and fecal output, fecal pH, fecal acetate and propionate concentrations, and viable numbers of DFM in the feed. With the exception of Fe digestibility, there were no starch x DFM interactions. There was an effect of starch level (P 0.10). Horses supplemented with LAC4 had increased ether extract (P < 0.05) and a tendency for decreased Na (P < 0.10) digestibilities compared with CON horses. All DFM-supplemented horses had increased Cu (P < 0.05) and Fe and numerically increased Zn digestibilities compared with CON horses. Fecal pH decreased (P < 0.05), and fecal propionate concentration increased (P < 0.05) as dietary starch content changed from LS to HS. There was a tendency for elevated fecal pH (P < 0.10) in LAC1 horses compared with CON horses. These results confirm that increasing starch in the equine diet can enhance nutrient digestibility of the diet. Supplementing equine diets with either a single or mixed strain direct-fed lactic acid bacteria had limited effects on nutrient digestibility or on reducing the risk of acidosis associated with feeding high-starch concentrates to horses. The potential response of DFM supplementation should be evaluated when a more acute acidotic state is induced in horses than in the current study.     

Wheat-barley-rye- or corn-fed growing pigs respond differently to dietary supplementation with a carbohydrase complex

Thirty-six pigs (22 kg of BW) were used to evaluate a carbohydrase preparation, with xylanase and β-glucanase as main activities, added to either wheat-barley-rye- (WBR) or corn-based diets on performance, intestinal environment, and nutrient digestibility. Pigs were offered 1 of 4 different dietary treatments for 27 d according to a factorial arrangement of treatments (a 2 × 2) with 2 cereal types (WBR or corn) and 2 levels of supplemental carbohydrase (0 or 0.01%). Pig growth and feed intake were individually measured every week until the end of the experiment when pigs were slaughtered to obtain samples of digesta and tissues. Cereal type affected performance only during wk 1, in which WBR improved ADG (590 vs. 440 g/d; P = 0.008) and G:F (0.61 vs. 0.43; P = 0.045) compared with corn. The WBR also increased the viscosity of the digestive contents in stomach (1.95 vs. 1.23 mPa·s; P = 0.001) and ileum (6.53 vs. 2.80 mPa·s; P = 0.001) and resulted in greater cecal starch digestibility (95.7 vs. 93.9%; P = 0.012). However, trends for a reduction in digestibility were observed for glucose in the nonstarch polysaccharide (NSP) fraction in the ileum (64.4 vs. 75.8%; P = 0.074) and galactose in the NSP fraction in the cecum (1.4 vs. 1.8%; P = 0.055). The use of the enzyme preparation increased ADFI during wk 2 (1,328 vs. 1,215 g/d; P = 0.028), and increased villus height (423 vs. 390 μm; P = 0.045) and tended to reduce relative pancreas weight (0.16 vs. 0.17% BW; P = 0.079) at d 27. The enzyme also improved cecal starch digestibility (95.5 vs. 94.1%; P = 0.043) and tended to improve ileal energy digestibility (61.3 vs. 53.7%; P = 0.090) and cecal glucose digestibility in the NSP fraction (76.0 vs. 54.5%; P = 0.055). However, it reduced the cecal digestibility of mannose in the NSP fraction (27.0 vs. 50.5%; P = 0.016). Interactions (P < 0.05) between cereal type and enzyme supplementation were observed for ADG and G:F during wk 2, BW and ADG during wk 3, and BW and ADFI over the whole trial; and also for villus-height-to-crypt-depth ratio and for cecal DM digestibility. In all instances, whereas the added enzyme had no effect in the case of the corn diet, improvements were observed with WBR. In conclusion, the multi-enzyme tested had different effects depending on the type of cereal present in the diet.     

Feeding and microbial disorders in horses: Part 3—Effects of three hay:grain ratios on microbial profile and activities

Cecal and colonic fluid contents were collected from three ponies and analyzed to determine the effects of three hay:barley ratios on their microbial and biochemical characteristics. Three diets based on chopped meadow hay and rolled barley were tested in a 3×3 Latin square experiment: 100% hay (100:0, 114gDM/KgBW^0.75/day), 70% hay-30% barley (70:30, 69gDM/KgBW^0.75/day) and 50% hay-50% barley (50:50, 58gDM/KgBW^0.75/day). Enumeration of total anaerobic and aero-anaerobic bacteria, lactate-utilizing and cellulolytic bacteria, lactobacilli and streptococci, as well as pH, lactate and VFA concentrations, were determined after 14 days adaptation to the new diet. In the large intestine, the concentrations of total bacteria were higher with the diets containing barley than with the hay diet, whereas cellulolytic bacteria were depressed with the concentrate diets. As the proportion of barley increased, concentration of lactate-utilizing bacteria, lactobacilli and streptococci increased in the colon while it did not interfere significantly on these populations in the cecum. These changes of the microflora were associated with a significant decrease in intestinal pH and [(acetate+butyrate)/propionate] ratio, and a numerical increase of lactate concentration.     

Effect of diet composition and feeding pattern on the prececal digestibility of starches from diverse botanical origins measured with the mobile nylon bag technique in horses

This trial was conducted to determine the extent of prececal starch digestibility depending on the botanical origin of starch and on diet characteristics (i.e., composition and feeding pattern). The prececal disappearance of six substrates (oats, barley, corn, horse bean, potato, and wheat) was measured in four cannulated horses fed (as-fed basis) 11.8 g/kg BW of a high-fiber (HF) or high-starch (HS) pelleted feed and 10.0 g/kg BW of meadow hay using the mobile bag technique (MBT). The daily feeding pattern was either three meals (two meals of pellets and one meal of hay) or five meals (three meals of pellets and two meals of hay). The experimental procedure was a 2 x 2 factorial arrangement tested in a Latin square design. After 2 wk of adaptation to the diet, collections were made on 5 d. Thirty nylon bags, composed of five bags of each substrate, were intubated to each horse during the ingestion of the morning meal. Bags were collected in the cecum, using a magnet, at 9 h postintubation. In spite of strong interindividual differences, approximately 80% of the intubated bags were collected. On average, the mean retention time of the bags was 6.2 h (+/-0.17). Regardless of the feeding pattern, the transit of the bags was faster when the fiber content of the diet was higher (P = 0.003). Likewise, regardless of the meal composition, transit was also faster when the ration was split into five daily meals (P = 0.001). The DM disappearance, corrected with particulate losses (DMD(c)), differed depending on the substrate tested (33.5, 57.1, 63.8, 67.7, 78.6, and 86.2% for potato, horse bean, oats, barley, corn, and wheat, respectively; P = 0.001). The DMD(c) of corn, barley, and potato was higher when HS was fed (P = 0.020); regardless of the substrate, DMD(c) was higher with five daily meals (P = 0.001). The starch disappearance (StarchD(c)) was different depending on the substrate (P = 0.001; 36.1, 71.2, 86.6, 89.2, 99.0, and 99.7% for potato, horse bean, barley, corn, wheat, and oats, respectively). Whatever the substrate, StarchD(c) was higher when HS was fed (P = 0.007), but it was not affected by the feeding pattern of the diet. Although passage rate was modified and feed intake was different, the botanical origin of starch was the main factor that affected prececal starch disappearance in horses.     

Effects of a twin strain of saccharomyces cerevisiae live cells on mixed ruminal microorganism fermentation in vitro

This experiment was designed to investigate the effects of different concentrations (0, 0.33, 0.66, 0.99, and 1.32 g/L) of a twin-strain of Saccharomyces cerevisiae live cells on in vitro mixed ruminal microorganism fermentation of corn starch, soluble potato starch, and sudangrass hay (60.5%, DM basis) plus concentrate mixture (39.5%, DM basis). Ruminal fluid was collected from two dairy cows, mixed with phosphate buffer (1:2), and incubated (30 mL) anaerobically at 38 degrees C for 6 and 24 h with or without yeast supplement, using 200 mg (DM basis) of each substrate. Medium pH, ammonia-N, and numbers of protozoa were unaffected (P = 0.38) by yeast cells in all substrates. Molar proportion of acetate was unchanged (P = 0.56) with cornstarch and soluble potato starch, but increased quadratically (P = 0.02) with hay plus concentrate by treatment. Addition of yeast cells caused a linear increase of total VFA (P = 0.008) in all substrates. Excluding the soluble potato starch, supplementation of S. cerevisiae resulted in a quadratic increase of propionate (P = 0.01), with a quadratic decrease (P = 0.04) of acetate:propionate. When soluble potato starch was used as a substrate, a linear increase (P = 0.006) of the molar proportion of propionate and a quadratic decrease (P = 0.007) in acetate:propionate was observed by treatment. Molar proportion of butyrate was unchanged (P = 0.35) with cornstarch and soluble potato starch, whereas it decreased linearly (P = 0.007) with hay plus concentrate by yeast cell supplementation. When cornstarch and soluble potato starch were used as a substrate, minor VFA were decreased (P = 0.05) by treatment. Accumulation of lactate was linearly decreased by treatment (P = 0.007) in all substrates. During incubation with hay plus concentrate, IVDMD was linearly increased (P = 0.006), whereas production of methane (linear; P = 0.02) and accumulation of hydrogen was decreased (quadratic; P = 0.005) by treatment after 24 h. These results showed that a twin strain of S. cerevisiae live cells stimulated in vitro mixed ruminal microorganism fermentation with decreased lactate, and a small decrease of methane and hydrogen with hay plus concentrate.     

Effect of Live Yeast Culture Supplementation on Fibrolytic and Saccharolytic Bacterial Populations in the Feces of Horses Fed a High-Fiber or High-Starch Diet

The objective of this study was to assess the effect of live yeast (Saccharomyces cerevisiae) supplementation on the populations of specific cellulolytic (Fibrobacter succinogenes and Ruminococcus flavefaciens) and saccharolytic (Streptococcus equinus and Streptococcus bovis) bacteria in the feces of horses fed high-starch and high-fiber diets. Four horses were each fed diets consisting of high fiber with no yeast (HF), high fiber with yeast (HFY), high starch with no yeast (HS), and high starch with yeast (HSY) in a 4 × 4 Latin-square design study. Fresh fecal samples were collected on the last 3 days of each 31-day experimental period and were then assessed, using semiquantitative real-time PCR, for total bacterial load and levels of target bacterial species, relative to the total bacterial load. The most abundant of the target species was F. succinogenes, and the HSY diet resulted in a significant (P = .045) reduction in relative levels of this bacterium. No significant effect (P = .224) of diet was observed in relation to abundance of R. flavefaciens. Results show that diet did not have a significant (P = .068) effect on relative quantities of S. equinus, although there appeared to be a trend for increased levels of this bacterium during feeding of high-starch diets. Numbers of S. bovis were higher (P < .001) when horses were fed HS and HSY diets than when fed the HF and HFY diets. Significant variation in levels of S. equinus (P = .024) and S. bovis (P = .049) was observed between individual horses.     

In vitro effects of the ionophore lysocellin on ruminal fermentation and microbial populations.

Batch and continuous culture techniques were used to evaluate the effect of the ionophore lysocellin on ruminal fermentation and microbial populations. In batch culture, .5 and 1 ppm (of the fluid) lysocellin markedly decreased (P less than .01) the acetate:propionate ratio without affecting fiber digestion, ammonia concentration, or culture pH. Greater concentrations of lysocellin had negative effects (P less than .05) on fiber digestion and increased (P less than .05) culture pH. In continuous culture, a low level of lysocellin (33 ppm of the diet DM or about .7 ppm of the fluid) decreased pH (P less than .05) and methane (P less than .05) production but had no effect on fiber digestion. Lysocellin tended to increase (P less than .05) OM digestion in corn-based diets but decreased OM digestion in barley-based diets (starch source x lysocellin interaction, P less than .05). In addition, the molar proportion of propionate was increased more in barley- than in corn-based diets. Total anaerobes and amylolytic and lactate-utilizing microorganisms were not affected by the ionophore. In continuous culture, cellulolytic and lactate-producing organisms were insensitive to lysocellin, but, in lysocellin-treated media, cellulolytic organisms were resistant, whereas lactic acid producers were sensitive to lysocellin at 4 ppm. In summary, the ionophore lysocellin alters ruminal fermentation by decreasing ruminal methane production and increasing the molar proportion of propionate; however, effects varied depending on whether corn or barley served as the primary starch source.     

Effects of ruminal and postruminal infusion of starch hydrolysate or glucose on the microbial ecology of the gastrointestinal tract in growing steers

Forty crossbred steers were used to determine the effects of carbohydrate supply site on the indigenous bacteria of the gastrointestinal tract. Steers were fitted with ruminal and abomasal infusion catheters and assigned randomly to one of eight groups in a complete randomized block design. The experimental period was 36 d. Treatments included: 1) a pelleted basal diet fed at 0.163 Mcal ME x (kg BW(0.75)) x 1 x d(-1) (LE); 2) the basal diet fed at 0.215 Mcal ME x (kg BW(0.75)) (-1) x d(-1) (HE); 3) the basal diet fed at 0.163 Mcal ME x (kg BW(0.75))(-1) x d(-1) with ruminal infusion of starch hydrolysate (SH) (RSH); 4) the basal diet fed at 0.163 Mcal ME x (kg BW(0.75))(-1) x d(-1) with abomasal infusion of SH (ASH); and 5) the basal diet fed at 0.163 Mcal ME x (kg BW(0.75))(-1) x d(-1) with abomasal infusion of glucose (AG). The total volume ofinfusate (5 kg x site(-1) x d(-1)) was equalized across treatments and infusion sites by infusion of water. Glucose and SH were infused at rates of 14.35 and 12.64 g x (kg BW(0.75)) x d(-1), respectively. Ruminal, cecal, and fecal samples were obtained on d 36. Ruminal pH was low (5.79) in LE steers and unaffected (P > 0.10) by increased energy intake or carbohydrate infusion. Cecal and fecal pH were 6.93 and 7.00, respectively, for LE steers. Increasing energy intake (P < 0.10) and the rate of carbohydrate infusion (P < 0.01) significantly decreased cecal and fecal pH compared with LE. Ruminal counts of anaerobic bacteria in LE steers were 8.99 log10 cells/g and abomasal carbohydrate infusion had no affect (P > 0.10) on these numbers. However, ASH and AG steers had approximately 1.5 log10 cells/g more (P < 0.01) cecal and fecal anaerobic populations. Ruminal, cecal, and fecal aerobic bacterial counts were 40, 22, and 23%, respectively, lower than anaerobic counts. Generally, aerobic counts responded similarly to the anaerobic counts. Less than 1% of the anaerobic bacteria enumerated in the rumen, cecum, and feces were coliforms, and 97% of the coliforms were Escherichia coli. Carbohydrate infusions resulted in only numerical increases in fecal coliform and E. coli concentrations (P > 0.10). Fecal E. coli were highly acid sensitive in all steers, with less than 1% surviving a 1-h exposure to low pH (2.0). This suggests that cecal or fecal pH is not a good indicator of acid resistance, and it supports the concept that there are other factors that may induce acid resistance.     

In vitro fermentation of various fiber and starch sources by pig fecal inocula

Freeze-dried ileal effluent (1% wt/vol) from cannulated pigs fed rice-based diets with the inclusion of either animal protein (CON), animal protein plus potato starch (PS), animal protein plus sugar beet pulp (SBP), or animal protein plus wheat bran (WB) was incubated anaerobically at pH 6.0 in fermenters containing 5% (wt/vol) fecal slurry comprising mineral salts medium and 50 g/L of fresh feces from pigs fed the same diets as the cannulated pigs. Samples were collected from the fermenters at 0, 2, 4, 12, 24, and 48 h during in vitro fermentation for measuring nonstarch polysaccharides (NSP), starch, and short-chain fatty acids (SCFA). Results showed that the major SCFA produced were acetate, propionate, and butyrate. The inclusion of soluble dietary fiber (diet SBP) caused the highest concentrations of acetate, propionate, butyrate, and total SCFA, whereas the increase in the production of propionate resulting from the addition of insoluble dietary fiber (diet WB) only occurred at the initial stages during 48 h in vitro fermentation. At all sampling occasions (except for 4 h), the levels of butyrate were increased (P < 0.01) by resistant starch compared with fiber sources, showing that a higher level of butyrate can be achieved through microbial fermentation by potato starch. Lowered (P < 0.05) butyrate concentrations were observed with diet WB during in vitro fermentation. With the inclusion of fiber sources, the energy originating from SCFA was similar to that from NSP disappearance, whereas the values were lower (P < 0.05) from NSP disappearance than for SCFA generated without fiber sources supplemented. We conclude that more substrate is available in ileal effluent with the addition of soluble dietary fiber, and an increased level of butyrate could be achieved through microbial fermentation by resistant starch.     

不同淀粉类型饲粮对育肥猪盲肠食糜主要微生物及其代谢产物的影响

本试验旨在研究不同淀粉类型饲粮对育肥猪盲肠食糜主要微生物及其代谢产物的影响。试验选取72头健康且初始体重相近的“杜×长×大”三元杂交阉公猪,随机分为3组,每组8个重复,每个重复3头猪。3组猪分别饲喂含有木薯淀粉、玉米淀粉和豌豆淀粉作为唯一淀粉来源配制的3种饲粮,饲粮的直链淀粉/支链淀粉分别为0.11、0.25和0.44。试验预试期4 d,正试期42 d。于正式试验的第42天,每个重复选取1头体重接近平均体重的猪进行屠宰,收集盲肠食糜进行相关指标的测定。结果表明:1)与木薯淀粉饲粮相比,豌豆淀粉饲粮显著降低育肥猪盲肠食糜的pH(P<0.05);2)与木薯淀粉饲粮相比,玉米淀粉和豌豆淀粉饲粮显著增加育肥猪盲肠食糜中乳酸的含量(P<0.05),同时豌豆淀粉饲粮显著增加食糜中乙酸、丁酸和总短链脂肪酸的含量(P<0.05);3)对于肠道微生物氮代谢产物而言,与木薯淀粉饲粮相比,玉米淀粉和豌豆淀粉饲粮显著降低育肥猪食糜中氨态氮、腐胺、总生物胺、吲哚和粪臭素的含量(P<0.05),同时豌豆淀粉饲粮显著降低食糜中尸胺和色胺的含量(P<0.05);4)对于微生物而言,与木薯淀粉饲粮相比,玉米淀粉和豌豆淀粉饲粮显著增加育肥猪盲肠食糜中普雷沃氏菌属的数量(P<0.05),而降低食糜中大肠杆菌的数量(P<0.05),同时豌豆淀粉饲粮增加了食糜中乳酸杆菌、双歧杆菌、梭菌Ⅳ和梭菌ⅩⅣ的数量(P<0.05)。由此可见,本试验条件下,给育肥猪饲喂含有高直链的豌豆淀粉改变了其盲肠食糜中微生物的组成和发酵模式,增加了部分有益菌的数量和碳水化合物代谢产物的含量,降低了潜在致病菌的数量和氮代谢产物的含量,这提示摄食含有高直链的淀粉有利于维持宿主肠道健康。     

Effects of Saccharomyces cerevisiae on In Vitro Mixed Ruminal Microorganism Fermentation

The objective of this study was to examine the effects of two Saccharomyces cerevisiae feed supplements on the in vitro mixed ruminal microorganism fermentation of ground corn, soluble starch, alfalfa hay, and Coastal bermudagrass hay. In the absence of added substrates, both yeast supplements increased (P<0.05) methane concentrations, whereas concentrations of acetate and propionate were numerically increased. In ground corn incubations, both concentrations (0.35 and 0.73 g/L) of both S. cerevisiae supplements had little effect on final pH or fermentation products. Both concentrations of each S. cerevisiae supplement numerically increased concentrations of acetate and butyrate in soluble starch fermentations. In addition, the 0.73-g/L treatment increased (P<0.10) propionate, and both yeast treatments decreased (P<0.05) acetate:propionate. In vitro DM disappearance of alfalfa hay and Coastal bermudagrass hay did increase over time. However, the addition of both concentrations of each S. cerevisiae supplement had little effect on either the rate or extent of digestion of either forage by mixed ruminal microorganisms. In general, both S. cerevisiae supplements seemed to have similar effects on the in vitro mixed ruminal microorganism fermentation.