Effect of transportation on fecal bacterial communities and fermentative activities in horses: impact of Saccharomyces cerevisiae CNCM I-1077 supplementation.

This study evaluated the effect of transportation on fecal bacterial communities and activities in horses with or without supplementation of live yeast and attempted to link those effects with changes in blood stress markers. Four mature horses were assigned to a crossover design and fed a basal diet (60:40 forage to concentrate; 1.45% BW on a DM basis), with or without supplementation, of 2 × 10(10) cfu/d of Saccharomyces cerevisiae CNCM I-1077. After a 14-d adaptation to dietary treatments, the 5-d experiment started 1 d before transportation (d -1). At d 0, horses were simultaneously transported in a truck for 2 h. Feces were sampled 4 h after the morning meal of concentrate at d -1, 0 (immediately after transportation), and 3 for enumeration of the main functional bacterial groups and determination of fermentative variables. Within each dietary treatment, feces were pooled before DNA extraction and molecular analysis of the bacterial communities, using temporal temperature gradient electrophoreses (TTGE). Blood samples were collected at the same time for determination of white blood cells (WBC) counts and glucose and total protein concentrations. Regardless of dietary treatment, the neutrophil to lymphocyte ratio increased during transportation (P < 0.01), indicating that horses were stressed. In both treatments, TTGE profiles were clearly different before and 3 d after transportation, and the percentage of similarity between profiles at d -1 and 3 was greater in supplemented horses compared with the controls. From d 0 to 3, the molar percentage of propionate increased and total concentration of VFA and the acetate + butyrate to propionate ratio decreased, regardless of dietary treatment (P < 0.01, P = 0.02, and P < 0.01, respectively), whereas pH decreased only in control horses (P = 0.03). Regardless of day of sampling, fecal concentrations of lactate-utilizing bacteria and cellulolytic bacteria were greater in supplemented horses than in control horses (P = 0.04 and 0.08, respectively). Our results indicate that transportation for 2 h disturbed the fecal bacterial ecosystem in horses that could increase the risk of triggering microbial dysbiosis on a longer term in the equine large intestine. Supplementing Saccharomyces cerevisiae CNCM I-1077 could help reduce the negative impact of transportation on the fecal bacterial ecosystem.

Effect of live yeast culture supplementation on hindgut microbial communities and their polysaccharidase and glycoside hydrolase activities in horses fed a high-fiber or high-starch diet.

Four cecum and right ventral colon-fistulated horses were assigned in a 4 x 4 Latin square design and fed a high-fiber (HF) or a high-starch (HS) diet with or without 10 g of Saccharomyces cerevisiae (SC; CBS 493.94) containing 4.5 x 10(9) cfu/g. The HF and HS diets consisted of pelleted feeds and long wheat straw (18.0 and 3.5 g of DM.kg(-1) of BW.d(-1), respectively) given in 2 equal meals to provide an NDF:starch ratio of 3.5 and 1.0, respectively. After a 21-d adaptation period intestinal contents were collected 4 h after the morning meal on d 23 and 25 to determine bacterial and SC concentrations. Polysaccharidase activities (CMCase, xylanase, amylase) and activities of glycoside hydrolases (alpha-l-arabinosidase, beta-d-cellobiosidase, beta-d-glucosidase, beta-d-xylosidase) were determined in liquid-associated bacteria (LAB) and solid-adherent bacteria (SAB) isolated from both compartments. Lactobacilli were increased in the cecum (P = 0.012) and colon (P = 0.086) when starch intake increased, whereas total anaerobes, cellulolytics, and streptococci did not change in either compartment. In yeast-supplemented horses, SC concentrations were greater in cecum (4.4 x 10(6) cfu/mL) than in right-ventral colon (5.6 x 10(4) cfu/mL) and did no change with diet. Concentrations of lactobacilli and lactic-acid utilizers were greater (P = 0.099 and 0.067, respectively) in the cecum but remained similar in the colon of SC-supplemented horses. The CMCase activities of SAB were not affected by diet. Colonic xylanase activities of SAB were reduced (P = 0.046) by starch addition, but no change was seen in the cecum. All SAB glucoside hydrolase activities in the cecum and colon, except beta-d-xylosidase in the cecum, were decreased when starch intake was increased. The LAB CMCase (P = 0.049 in the colon) and xylanase (P = 0.021 in the cecum; P < 0.001 in the colon) activities decreased with starch intake. No effect of starch on LAB or SAB amylase activity was observed. Addition of SC improved SAB CMCase in the cecum (P = 0.019) and colon (P = 0.037) as well as beta-d-cellobiosidase (P = 0.002) and beta-d-glucosidase (P = 0.041) in the cecum. Only xylanase in the cecum (P = 0.015) and beta-d-xylosidase in the cecum (P = 0.028) were improved with SC, whereas colonic LAB alpha-amylase activity was significantly decreased (P = 0.046). Most enzymes involved in plant cell wall digestion were increased after SC addition. This fact may contribute to explain a better digestion of fiber that has been previously reported in SC-supplemented horses.

Effects on the equine colon ecosystem of grass silage and haylage diets after an abrupt change from hay.

The objective of this study was to investigate the effect of an abrupt change from grass hay (81% DM) to grass silage (36% DM) or grass haylage (55% DM), fed at similar DM intakes, and to compare the effects of silage and haylage on the composition and activities of the colon microflora. The forages were from the same swath harvested on the same day. Four adult colon-fistulated geldings were randomly assigned to diets in a crossover design. The study started with a preperiod when all 4 horses received the hay diet, followed by an abrupt feed change to the haylage diet for 2 horses and the silage diet for 2 horses. All 4 horses then had a new second preperiod of hay, followed by an abrupt feed change to the opposite haylage and silage diet. The periods were 21 d long, and the forage-only diets were supplemented with minerals and salt. The abrupt feed changes were made at 0800 h. Colon samples were taken before the abrupt feed change, 4 and 28 h after the feed change, and 8, 15, and 21 d after the feed change, all at 1200 h. Colon bacterial counts, VFA, pH, and DM concentrations were unchanged throughout the first 28 h after the abrupt feed change from hay to haylage and silage. Also, fecal pH and DM concentrations were unchanged during the first 28 h. During the weekly observations, colon lactobacilli counts increased (P = 0.023) in horses receiving the silage diet and were greater than on the haylage diet at 21 d. Streptococci counts decreased (P = 0.046) in horses receiving the haylage diet and were less than on the silage diet at 15 and 21 d. Total VFA concentrations and colon and fecal pH did not differ between diets and were unchanged throughout the weekly observations. The DM concentration of colon digesta and feces decreased (P = 0.030 and 0.049, respectively) on both diets during the weekly observations. The results suggest that in horses fed at the maintenance level of energy intake, an abrupt feed change from grass hay to grass silage or grass haylage from the same crop does not induce any major alterations in the colon ecosystem during the first 28 h. During the subsequent 3-wk period, colon and fecal DM decreased and there were alterations in the lactobacilli and streptococci bacterial counts. The changes in lactobacilli and streptococci counts need further investigation.

Effects of dietary short-chain fructooligosaccharides on the intestinal microflora of horses subjected to a sudden change in diet.

Prebiotic compounds, such as short-chain fructooligosaccharides (scFOS), have been shown to improve health, welfare, or both, in several species, but few studies have been conducted in horses, despite the sensitivity of their hindgut microflora. We hypothesized that prebiotic oligosaccharides, known to be able to stabilize the intestinal microflora in other species, would be of importance in horses. Our study was designed to evaluate the effect of scFOS supplementation on the equine intestinal microflora and to assess its effectiveness in reducing hindgut microbial disturbances related to sudden diet changes. Four adult geldings were allotted by weight into 2 groups and assigned to diets with and without (control) scFOS supplementation for 21 d in a crossover design. Cecal and colonic contents were collected through cannulas to assess the effect of an abrupt incorporation of barley in the diet of horses on microbial populations and fermentation variables. The addition of barley to the control diet caused substantial changes in the colonic microflora, such as increases (P < 0.05) in the concentration in total anaerobes, lactobacilli, streptococci, and lactate-utilizing bacteria. The scFOS supplementation reduced the barley intake-related changes. In contrast to the control diet, Lactobacillus and Streptococcus populations did not increase. Although the colonic d-lactate concentration increased (P < 0.05) after the meal of barley in the control group, it did not accumulate with scFOS supplementation. These data indicate that a scFOS supplementation would be effective in reducing disruptions of the microbial populations in the equine hindgut under stressful situations like acute starch overloads.

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.

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.