Influence of ciliate protozoa on biochemical changes and hydrolytic enzyme profile in the rumen ecosystem

AIMS: To assess the effect of presence or absence of rumen protozoa on fermentation characteristics and enzyme profile in growing lambs. METHODS AND RESULTS: Weaner lambs (G1, G2, G3, G4, G5 and G6 groups) were defaunated by oral administration of sodium laurel sulphate (at 8 g 100 kg(-1) body weight). The lambs of G4, G5 and G6 groups were refaunated. The roughage and concentrate ratio in the diet of G1 and G4, G2 and G5, and G3 and G6 were 50:50 (R1), 65:35 (R2) and 80:20 (R3), respectively. Daily dry matter intake was similar in defaunated and faunated lambs. However, digestibility of organic matter (OM), cellulose and gross energy were lower in defaunated lambs while crude protein (CP) digestibility was similar in both defaunated and faunated lambs. The rumen pH and NH3-N were lower (P < 0.01) while TVFA, total-N and TCA-ppt-N were higher (P < 0.01), in defaunated lambs. Ruminal activity of carboxymethyl cellulase was lower (P < 0.01) in defaunated lambs and amylase, xylanase, protease and urease were similar in faunated and defaunated lambs. Nutrient utilization, rumen metabolites and ciliate protozoal count were higher, whereas digestibility of fibre fractions was lower in high rather than low concentrate fed lambs. The rumen protozoa present before defaunation were B-type and the protozoa which re-established on refaunation were also B-type. CONCLUSIONS: Absence of ciliate protozoa decreased nutrient digestibility and increased ruminal TVFA and total-N with lower NH3-N concentration, indicating better energy and protein utilization in defaunated lambs. SIGNIFICANCE AND IMPACT OF THE STUDY: Defaunation improved energy and protein utilization in lambs.     

Feed digestion,rumen fermentation and blood biochemical constituents in Malpura rams fed a complete feed-block diet with the inclusion of tree leaves

This experiment assayed the influence of the inclusion of dried Azardirachta indica, Albizzia lebbek or Ailanthus excelsa leaves in pearl millet stover-based complete feed block diets on feed intake, nutrient utilization, rumen fermentation characteristics, ciliate protozoa population and blood biochemical constituents in adult Malpura sheep. Complete feed blocks were formulated to have roughage-to-concentrate ratio of 70:30. Pearl millet stover (PMS) was used as basal roughage; 30 parts of pearl millet stover was replaced with dried leaves either of Azardirachta indica (NL), Albizzia lebbek (SL) or Ailanthus excelsa (AL). Twelve hogget Malpura rams, divided into four equal groups, were offered one of the four dietary treatments. A feeding-cum-metabolic trial was conducted to assess nutrient utilization. Rumen liquor samples were collected at 0, 3, 6, 12, 18 and 24 h post-feeding to assess rumen fermentation pattern and ciliate protozoa population. Inclusion of dried leaves in PMS-based diets improved CP and DCP content. Dietary DCP was low (P < 0.01) in PMS (8.52%) compared to tree leaves (9.77–11.59%) diets. AL and NL diets had higher (P < 0.05) DCP than the SL diet. The inclusion of tree leaves did not influence organic matter, crude protein or cellulose digestibility, but depressed dry matter, NDF, ADF and energy digestibility. DE content was also lower in tree leave diets. Inclusion of tree leaves improved CP and DCP intake, but DE intake and nitrogen utilization did not change. The pH of rumen liquor (SRL) was low (6.99, P < 0.05), but total nitrogen (52.9 mg/dl SRL) and NH₃-nitrogen (9.34 mg/dl SRL) concentrations were higher (P < 0.01) in the AL diet. TVFA concentrations and ciliate protozoa population were similar on the four diets. Animals in the four groups had the desired concentration of rumen metabolites required for fibrous diets. Complete feed-block feeding provided a constant nutrient supply to rumen microbes that optimise rumen fermentation. Blood biochemical constituents did not change due to the inclusion of tree leaves. Therefore, tree leaves can be included with roughage-based feeding to improve the protein nutrition status of ruminants. Further studies are required to assess the negative influence of tree leaves on digestibility.     

Predation of Salmonella enterica serovar Typhimurium by the rumen protozoon Entodinium caudatum studied in vitro by fluorescence emission

Predation of bacteria by protozoa has important implications on rumen metabolism and bacterial populations. Protozoa can also restrict the passage of pathogenic bacteria to the host’s lower gastrointestinal tract. This work aimed to evaluate the predation by Entodinium caudatum (EC) and the intraprotozoal survival of Salmonella enterica serovar Typhimurium. EC cells from a monofaunated sheep were incubated for up to 105 min with a S. enterica strain producing a green fluorescent protein. Rumen fluid from a defaunated sheep (DEF) was used as a control. Fluorescence, as an index of predation, measured in the residual (protozoal) fraction was higher in EC than in DEF. 105 min after the beginning of the incubation it was higher than 30 min after. Intracellular survival of Salmonella within EC was assessed by means of a selective medium. Amounts of Salmonella in the residual fraction were higher in EC than in DEF only after 30 min. After 105 min, each protozoa engulfed 100 Salmonella cell per min. Intraprotozoal survival of ingested Salmonella was 0.0017. Predation of S. enterica by E. caudatum occurred and increased in proportion to time, but bacterial viability inside the protozoa was lower at 105 min. This study demonstrates that fluorescence emission combined with bacterial and protozoal cultures could be a reliable method for quantifying bacterial predation and viability in vitro.     

Effects of dietary whole cottonseed and crude protein level on rumen protozoal population and fermentation parameters

In this investigation in vitro and in vivo trials were performed to determine the efficacy of a cottonseed to limit protozoal population and fermentation parameters. The composition of diets given to the different treatments were as follow: (1) control (without whole cottonseed), 16% crude protein (CP), 3.2% ether extract (E.E.); (2) 20% whole cottonseed, 16% CP, 6.5% E.E.; (3) 20% whole cottonseed, 13% CP, 6.4% E.E. and (4) 20% crushed whole cottonseed, 13% CP, 6.4% E.E. DM disappearance (DMD) and fermentation characteristics of the treatments were determined by in vitro incubation studies. In the in vivo trial, ruminal fluid was taken by rumenocentesis (3 h after feeding) on days 1, 3, 5, 7, 9, 11, 14, 21 and 28 from four sheep fed about treatment diets. The pH and protozoal counts were determined in each sample, while ammonia nitrogen and volatile fatty acid (VFA) were determined in samples taken on days 7, 14, 21 and 28. The in vitro DMD after 24 h incubation decreased (p < 0.01) with the addition of cottonseed in diets 3 and 4 and DMD after 72 h incubation was highest (p < 0.01) for the control diet. The fractional rate of gas production (c) for the control and diet 2 was higher (p < 0.05) than for the diets 3 and 4. Feeding crushed whole cottonseed decreased molar proportion of propionate (p < 0.05) and increased molar proportion of butyrate (p < 0.01). Low crude protein level increased the molar proportion of propionate (p < 0.05) and decreased molar proportion of butyrate (p < 0.05) and cellolytic protozoa population (p < 0.05). Feeding cottonseed decreased (p < 0.05) the total protozoa population from approximately 500,000 to 250,000 ml⁻¹ and Holotrich and cellulolytic protozoa disappeared from the rumen of sheep and only Entodinium sp., remained. This was associated with lower concentration of ammonia nitrogen in rumen fluid of sheep fed diets 4 (p < 0.05) and 2 (p < 0.01). It was concluded that cottonseed reduced rumen fauna and ammonia nitrogen, but had no effect on ruminal VFA while the crushed whole cottonseed decreased molar proportion of isovalerate only. In vivo molar proportion of propionate and butyrate and valerate were increase and decrease, respectively, by decreasing CP percentage in treatment diets.     

Ruminal ochratoxin A degradation—Contribution of the different microbial populations and influence of diet

The mycotoxin ochratoxin A (OTA) is degraded extensively in the rumen. In this study, the relative contribution of different rumen microbial populations (MP) and the effect of diet on degradation of OTA were evaluated in a factorial design experiment. Degradation of OTA was quantified by using the Hohenheim gas test (HGT) in vitro fermentation system. Five different HGT diets were used (concentrate:forage proportions (C:F) – 10:90, 30:70, 50:50, 70:30, 90:10), and donor animals were fed diets with the respective ratio. Diets with the highest concentrate content were supplied with and without 10 g/kg sodium bicarbonate (70:30 BC and 90:10 BC). The MP included whole rumen fluid, fungi + protozoa, bacteria + protozoa, protozoa and bacteria + fungi. Protozoa numbers were counted after 24 h and OTA and ochratoxin alpha (OTα) analysed at 0, 4, 8, 12, 24 h. Area under the curve (AUC) and half-life were calculated for the latter two. The short average OTA half-life for whole rumen fluid of 2.6 h (1.3–4.5 h) demonstrates the high OTA degradation capacity of the rumen MP (i.e., standard HGT inoculum) and corresponds well with published in vivo results. Both MP and diet affected OTA degradation. Interactions among factors occurred (P<0.001), which made it necessary to do further comparisons within factor levels. Among MP, those with bacteria (bacteria + fungi and bacteria + protozoa) had lower AUC values (P<0.001) for OTA (196–673 ng/ml h, meaning higher degradation capacity, than those without bacteria (fungi + protozoa and protozoa; 701–1206 ng/ml h). Whole rumen fluid had the lowest AUC values (146–249 ng/ml h; P<0.05). Diet had a quadratic effect (P=0.001) on protozoal numbers with minimum values for the lowest and highest C:F ratios, for bacteria + protozoa, fungi + protozoa and protozoa, but no corresponding effect was found for OTA degradation parameters. While the generally high capacity to degrade OTA was confirmed, results for the contribution of different microbial groups shed new light on ruminal OTA degradation.     

Effect of ciliate protozoa on the activity of polysaccharide-degrading enzymes and fibre breakdown in the rumen ecosystem

The effect of ciliate protozoa on the activity of polysaccharide-degrading enzymes in microbial populations from the digesta solids and liquor fractions of rumen contents was examined after the refaunation of ciliate-free sheep with an A-type rumen protozoal population. Although the culturable rumen bacterial population was reduced after refaunation the number of fibrolytic micro-organisms detected was higher; the xylanolytic bacterial population and numbers of fungal zoospores were increased after refaunation. The proportion of propionic acid was lower in the refaunated animals, whereas the concentration of ammonia and the acidic metabolites acetate, butyrate and valerate were all increased. The range of enzyme activities present in the digesta subpopulations were the same in defaunated and refaunated animals. The activities of the polysaccharide-degrading enzymes, however, were increased in the microbial populations associated with the digesta solids after refaunation, and at 16 h after feeding the activities were 4–8 times (β-d-xylosidase 20 times) higher than the levels detected in the adherent population from defaunated sheep. The protozoa, either directly through their own enzymes or indirectly as a consequence of their effects on the population size and activity of the other fibrolytic micro-organisms present, have an important role in determining the level of activity of polysaccharide-degrading enzymes in the rumen ecosystem. Although the extent of ryegrass ( Lolium perenne ) hay digestion was similar after 24 h in the absence or presence of protozoa, the initial ruminal degradation was higher in refaunated sheep.     

Effect of ciliate protozoa on the activity of polysaccharide-degrading enzymes and fibre breakdown in the rumen ecosystem.

The effect of ciliate protozoa on the activity of polysaccharide-degrading enzymes in microbial populations from the digesta solids and liquor fractions of rumen contents was examined after the refaunation of ciliate-free sheep with an A-type rumen protozoal population. Although the culturable rumen bacterial population was reduced after refaunation the number of fibrolytic micro-organisms detected was higher; the xylanolytic bacterial population and numbers of fungal zoospores were increased after refaunation. The proportion of propionic acid was lower in the refaunated animals, whereas the concentration of ammonia and the acidic metabolites acetate, butyrate and valerate were all increased. The range of enzyme activities present in the digesta subpopulations were the same in defaunated and refaunated animals. The activities of the polysaccharide-degrading enzymes, however, were increased in the microbial populations associated with the digesta solids after refaunation, and at 16 h after feeding the activities were 4-8 times (beta-D-xylosidase 20 times) higher than the levels detected in the adherent population from defaunated sheep. The protozoa, either directly through their own enzymes or indirectly as a consequence of their effects on the population size and activity of the other fibrolytic micro-organisms present, have an important role in determining the level of activity of polysaccharide-degrading enzymes in the rumen ecosystem. Although the extent of ryegrass (Lolium perenne) hay digestion was similar after 24 h in the absence or presence of protozoa, the initial ruminal degradation was higher in refaunated sheep.     

Relationship Between Rumen Ammonia Levels and the Microbial Population and Volatile Fatty Acid Proportions in Faunated and Defaunated Sheep

Cheviot wethers were defaunated by using dioctyl sodium sulfosuccinate and were constantly infused with urea to provide 2.87% of the daily N intake. Defaunation resulted in higher rumen dry matter and lower rumen pH. The molar per cent propionate was higher in defaunated sheep, whereas the molar per cent butyrate and acetate was lower. Apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance were higher in defaunated sheep when compared with faunated animals. Urea infusion resulted in lower apparent nitrogen digestibility, nitrogen utilization, and nitrogen balance in faunated sheep, but did not affect nitrogen metabolism in defaunated sheep. Rumen ammonia-N levels in defaunated sheep were lower than those observed for faunated animals, and urea infusion into faunated sheep increased rumen ammonia-N levels to a greater extent than did the urea infusion into defaunated animals. Significant correlations were demonstrated between rumen ammonia-N levels and C(2)/C(3), C(3)/C(4) and C(2)/C(4) volatile acid ratios. From this it was concluded that, as rumen ammonia-N levels increased, there was a shift from propionate to higher proportions of butyrate and acetate.     

Effect of elemental nano-selenium on feed digestibility,rumen fermentation,and purine derivatives in sheep

The objective of this experiment was to study the effect of elemental nano-selenium (NS) on feed digestibility, rumen fermentation, and urinary purine derivatives in sheep. Eight male ruminally cannulated sheep (42.5 ± 3.2 kg of body weight, BW) were used in a replicated 4×4 Latin square experiment in four 20 day periods. Depending on treatment designation, sheep were fed the basal diet supplemented with 0 (control), 0.3, 3 and 6 g of nano-Se/kg dry matter (DM). Ruminal pH (range of 6.68–6.80) and ammonia N concentration (range of 9.95–12.49 mg/100 mL) was decreased (P<0.01), and total VFA concentration (range of 73.63–77.72 mM) was increased linearly (P<0.01) and quadratically (P<0.01) with increasing nano-Se supplementation. The ratio of acetate to propionate was linearly (P<0.01) and quadratically (P<0.01) decreased due to the increasing of propionate concentration. In situ ruminal neutral detergent fiber (aNDF) degradation of Leymus chinensis and crude protein (CP) of soybean meal were linearly (P<0.01) and quadratically (P<0.01) improved by feeding nano-Se. Similarly, nutrients digestibility in the total tract and urinary excretion of purine derivatives were also quadratically (P<0.01) changed by increasing nano-Se supplementation. The present results indicated that nano-Se supplementation in basal diet improved rumen fermentation and feed utilization. Nano-Se could also stimulate rumen microbial activity, digestive microorganisms or enzyme activity. The optimum dose of nano-Se was about 3.0 g/kg dietary DM in sheep.     

Studies on the in vitro cultivation of ciliate protozoa from the kangaroo forestomach

The methods used for culturing rumen protozoa were found to be unsatisfactory for growth of ciliate protozoa from the kangaroo forestomach. Based on published measurements of physical parameters in the marsupial forestomach, several modifications were incorporated into the procedure, i.e., an increase in % hydrogen in the gas phase, adjustment of initial pH of the medium to 6.9–7.0 range, feed only forage as a substrate and incubate at a lower temperature (33–36 °C). Only incubation at the lower temperature increased survival time of the kangaroo protozoa. Two species of Bitricha were still viable after 28 d in culture. Cultures had to be terminated at that time. One of the species differed considerably in size and shape from previously described species and based on 18S rRNA data, may represent a new species of Bitricha. The second species, present in low numbers was identified as Bitricha oblata. In a separate trial, Macropodinium yalanbense survived for 11 d, at which time these cultures also had to be terminated.     

The relationship between the volatile fatty acids supply and the nitrogen retention in growing sheep nourished by total intragastric infusions

Twelve four-month old Suffolk × Small-tail-Han male sheep (live weight 21–26 kg), fitted with rumen and abomasum fistulas and nourished by total intragastric infusions, were used to study the relationship between the volatile fatty acids (VFA) supply and the nitrogen (N) retention in sheep. The animals were randomly divided into four groups and four levels of mixed VFA energy (the molar proportion of acetic acid, propionic acid and butyric acid was 65:25:10), i.e. 333, 378, 423 and 468 kJ kg^?1 W^0.75 d^?1, were infused into the rumen, as treatments I, II, III and IV, respectively. The results showed that the N retention was significantly increased (P < 0.05) with the VFA infusion level. Significant regression relationship was found between the VFA supply (x, g d^?1) and the N retention (y, mg d^?1): y = 2.75x ? 403, r² = 0.86, n = 12, P < 0.01. It was concluded that to get efficient utilization of dietary N and high N retention in sheep, it is necessary to supply enough dietary energy.     

Influences of flavomycin,ropadiar, and saponin on nutrient digestibility,rumen fermentation,and methane emission from sheep

This study focused on the effects of three additives given together with a hay/concentrate-based diet on nutrient digestibility, rumen fermentation, and methane emission from sheep. The basal diet consisted of 1.29 kg mixed hay and 0.43 kg concentrate mixture based on dry matter (DM). Treatments consisted of control (no additive), flavomycin⁴⁰ (250 mg/d), ropadiar from an oregano extract (250 mg/d), and saponin in the form of a yucca schidigera extract (170 mg/d). Results indicated that intake and digestibility were unaffected by treatments (P>0.05). The NH₃-N concentration of rumen liquor was lower (P<0.05) for additive treatments versus the control treatment. Higher concentrations of volatile fatty acid (VFA) were observed in the saponin (75.8 mmol/L) and ropadiar (73.1 mmol/L) treatments. The proportion of individual fatty acid of rumen liquor was unchanged, whereas lower ratio of acetate to propionate in the saponin treatment was observed (P<0.05). The average methane production expressed on digested organic matter (OM) and neutral detergent fiber (aNDFom) basis were decreased by approximately 3.3 and 12.0 g/kg, respectively in saponin, and 4.2 and 11.9 g/kg in ropadiar treatment compared to the control. Methane production was positively correlated with the concentrations of NH₃-N, and negatively correlated with total VFA and the proportion of propionate of rumen liquor (P<0.05). The study found that saponin and ropadiar could have the potential to reduce rumen methanogenesis in sheep.     

Nutrient composition,digestion and rumen fermentation in sheep of wheat straw treated with calcium oxide,sodium hydroxide and alkaline hydrogen peroxide

This study tested the effect of calcium oxide (CaO), sodium hydroxide (NaOH) and NaOH plus hydrogen peroxide (H₂O₂; AHP) on cell wall composition, digestion and fermentation of wheat straw (straw) in sheep. Treated straws were prepared by mixing straw either with water followed by dusting with CaO at 160 g kg⁻¹ DM or with a NaOH solution alone at 3 l kg⁻¹ DM to supply 80 g NaOH kg⁻¹ DM (Na) or pre-soaked with Na exactly as in the previous treatment for 27 h followed by mixing with 130 g H₂O₂ kg⁻¹ DM (AHP) for 6 h. After 14 days of storage, the treated straws and an untreated straw (U) were fed automatically every 2 h to four individually housed sheep together with a supplement in a 4×4 latin square experiment. Each kilogram supplement DM contained 422 g CP and 10.8 MJ ME. NDF (p<0.001) and hemicellulose (p<0.01) contents were significantly reduced whereas cellulose was increased (p<0.001) in treated compared to untreated straw. ADL was reduced in Ca (p<0.05) but increased (p<0.05) in Na and AHP compared with U. The rumen and total tract digestibility were significantly (p<0.001) greater in sheep fed treated compared with untreated straw. Significant differences (p<0.05) between treatments for pH, NH₃ and VFA were also observed. All treatments improved the nutritive value of straws compared with untreated through modification of cell wall with a subsequent increase in digestibility by sheep. Although the digestibility for Ca was lower than that for Na despite reduction in cell wall, its use to treat straws may be more safe and cost effective than Na. AHP was the most effective and could also improve the energy value of other low quality forages for ruminants. However, the need of AHP for a large amount of NaOH to achieve highly alkaline pH limits its farm scale application. Therefore, further studies should either consider reducing the amount of NaOH or finding alternative alkalis that are cost effective and user-friendly.     

Influence of natural magnesium sources on the in vitro fermentation and protozoan population in the rumen fluid collected from sheep

The objective of this experiment was to determine the effect of two types of caustic calcinated magnesite (caustic magnesite (CM) and Agromag (AG)) upon the end products of in vitro fermentation (total gas, methane, total and individual fatty acids, and VFA) and protozoan population in the rumen fluid collected from sheep. Both magnesium additives (CM and AG) as natural products in the dose of 0.01 g were added to the fermentation bottles containing rumen inoculum from sheep and different substrates. Meadow hay (MH), wheat straw (WS), amorphous cellulose (AC) and barley grain (BG) were used as substrates and incubated with the buffered rumen fluid using an in vitro gas measuring technique during 72 h of incubation. The rumen protozoa, Entodinium spp., Trichostomatids and large Entodiniomorphids and the total protozoan concentration were counted after 24 h of incubation. The methane production was significantly decreased with CM or AG, respectively, by 58 or 62% (MH), by 65% (WS), by 52% (AC) and by 58% (BG). The total VFA concentration was significantly lower compared to control for CM plus MH, WS, AC, BG and AG plus WS. The total VFA concentration was significantly higher compared to control for AG plus AC. The effect of the both additives on ciliate population was not uniform and depended on the substrates used and protozoan type. Ciliate population was significantly increased in Entodinium spp. (AG plus BG) and Diploplastron affinae (CM or AG plus BG) compared to control. Tested additives significantly decreased population of Entodinium spp. (AG plus MH or AC), Dasytricha ruminantium (AG plus AC), Ophryoscolex c. tricoronatus, Eremoplastron dilobum and Polyplastron multivesiculatum (CM or AG plus BG). It can be concluded that both natural magnesium sources influenced rumen fermentation patterns and protozoan population in vitro depending on the type of the substrate used; therefore, the relative efficacy of individual tested additive cannot be determined from these experiments. In vivo experiments are required in future.     

The effect of rumen ciliates on chitinolytic activity,chitin content and the number of fungal zoospores in the rumen fluid of sheep

The objective of this study was to investigate the effect of selected protozoa on the degradation and concentration of chitin and the numbers of fungal zoospores in the rumen fluid of sheep. Three adult ewes were fed a hay-concentrate diet, defaunated, then monofaunated with Entodinium caudatum or Diploplastron affine alone and refaunated with natural rumen fauna. The average density of the protozoa population varied from 6.1 · 10⁴ (D. affine) to 42.2 · 10⁴ cells/ml rumen fluid (natural rumen fauna). The inoculation of protozoa in the rumen of defaunated sheep increased the total activity of chitinolytic enzymes from 2.9 to 3.6 μmol N-acetylglucosamine/g dry matter (DM) of rumen fluid per min, the chitin concentration from 6.3 to 7.2 mg/g DM of rumen fluid and the number of fungal zoospores from 8.1 to 10.9 · 10⁵ cells/ml rumen fluid. All examined indices showed diurnal variations. Ciliate population density was highest immediately prior to feeding and lowest at 4 h thereafter. The opposite effects were observed for the numbers of fungal zoospores, the chitin concentration and chitinolytic activity. Furthermore, it was found that chitin from zoospores may account for up to 95% of total microbial chitin in the rumen fluid of sheep. In summary, the examined ciliate species showed the ability of chitin degradation as well as a positive influence on the development of the ruminal fungal population.     

Influences of short-term pre-slaughter dietary manipulation in sheep and goats on pH and microbial loads of gastrointestinal tract

Sheep (BW = 39.9 kg, n = 16) and goats (BW = 32.8 kg, n = 16) were used in a completely randomized design to determine the effect of short-term pre-slaughter diet and feed deprivation (FD) time on pH and microbial loads in the gastrointestinal tract (GIT) contents. In a 2 × 2 × 2 factorial treatment arrangement, the main effects of species, diet, and FD time prior to slaughter and their interactions were studied. Animals were fed either a hay or concentrate diet for 4 d and then feed deprived for either 12 or 24-h prior to slaughter. The pH of rumen and colon contents as well as weight of GIT was measured. The contents of rumen and rectum were also sampled for microbial analysis. The GIT of sheep (1.82 kg) was heavier (P < 0.05) than that of goats (1.46 kg). The 12-h FD group (1.74 kg) had a higher (P < 0.05) GIT weight than the 24-h FD group (1.53 kg). Hay-fed animals had higher (P < 0.05) rumen (7.08 vs. 6.43) and colon pH values (7.02 vs. 6.56) than those of the concentrate-fed animals. The 24-h FD group (3.39 ± 0.272 log₁₀CFU/g) contained more (P < 0.05) Escherichia coli in the rumen than did the 12-h FD (2.17 ± 0.272 log₁₀CFU/g) group. The concentrate-fed animals (3.49 ± 0.289 log₁₀CFU/g) had higher (P < 0.05) coliform counts in the rumen than the hay-fed animals (2.43 ± 0.289 log₁₀CFU/g). The 24-h FD group (3.42 ± 0.289 log₁₀CFU/g) had a higher (P < 0.05) concentration of coliform than did the 12-h FD group (2.50 ± 0.289 log₁₀CFU/g). The 24-h FD group (3.31 ± 0.259 log₁₀CFU/g) also had higher (P < 0.05) Enterobacteriaceae counts in the rumen than did in the 12-h FD group (2.47 ± 0.259 log₁₀CFU/g). Goats (5.71 ± 0.158 log₁₀CFU/g) had lower (P < 0.05) total plate counts in the rumen compared to sheep (6.27 ± 0.158 log₁₀CFU/g). The concentrate-fed animals had higher (P < 0.05) E. coli (6.44 vs. 4.01 ± 0.468 log₁₀CFU/g), total coliform (6.74 vs. 4.16 ± 0.469 log₁₀CFU/g), Enterobacteriaceae (6.93 vs. 3.83 ± 0.651 log₁₀CFU/g), and total plate counts (7.79 vs. 7.28 ± 0.170 log₁₀CFU/g) in the rectum than the hay-fed animals. The results indicate that microbial loads in the GIT of small ruminants may be reduced by either feeding hay for 4 d or depriving feed for 12-h prior to slaughter.     

Effect of breed on response to foot rot treatment in mature sheep and lambs

Our objective was to determine whether breed differences existed in response to exposure and treatment of virulent foot rot. Dorset (DS), 1/2 Dorper (DX), 3/4 or greater Dorper (DO), Gulf Coast Native (GC), Katahdin (KA), and St. Croix (SC) mature sheep and lambs were exposed to virulent foot rot in spring 2003. Treatment for foot rot was initiated in 132 lambs and 262 mature sheep in late July. There were eight pasture groups treated, two of which were minimally exposed to foot rot. Treatment included hoof paring, foot bathing with 10% zinc sulfate with surfactant, allowing the zinc sulfate to dry on the foot and moving to a small paddock that had not been exposed to small ruminants for more than 14 d. Foot bathing was repeated every 7 d for a maximum of five treatments. Animals that had not responded (odor or any indication of persistent infection) by then were culled from the flock. As an indication of severity of foot rot for each animal, the number of areas on the foot (interdigital and two digits for each foot), a foot score (0 = no infection found; 1 = infection of digits only; 2 = infection of interdigital area and could include digits), and presence of characteristic odor was recorded. Least squares means for number of areas infected were greater for mature than growing sheep (2.07 ± 0.16 versus 0.88 ± 0.31; P < 0.001), for highly than minimally exposed groups (2.89 ± 0.17 versus 0.05 ± 0.29; P < 0.001), and DX compared with other breed types (P < 0.03). Percentage of sheep with odor was similar between age groups, was greater in the highly exposed groups (11.4 ± 1.9 versus 2.1 ± 3.4; P < 0.02), and greater in DO compared with DS, KA, and SC breeds (P < 0.001). Foot score was similar among breeds and greater in the highly exposed groups (age by group, P < 0.05). Percentage of sheep culled for failure to respond to foot bath treatment was greater for the highly than minimally exposed group (22.9 ± 2.3 versus 0.0 ± 3.9; P < 0.001) and greater for mature sheep compared with lambs (P < 0.001) and similar among breeds. In November, four ewes in a large group and two lambs in a small group were determined to have foot rot and were immediately culled. The two groups containing these ewes were re-treated for 2 weeks and were determined to be free of foot rot (no further signs of lameness). Response to foot rot eradication appeared to be similar among breeds examined.     

The relationship between fetal and maternal selenium concentrations in sheep and goats

In this study, biological samples (slaughterhouse material) were collected from 30 sheep and 36 goats and classified according to gestational stage into either early or late gestation. Samples consisted of allantoic fluid, amniotic fluid, fetal liver, fetal kidney, fetal thyroid gland, maternal plasma and liver to determine selenium (Se) concentrations throughout gestation. The Se concentrations in the allantoic fluid, fetal liver and kidney increased significantly (p < 0.01) during late gestation. Concurrently, the Se concentrations in amniotic fluid, maternal plasma and liver decreased significantly (p < 0.01) over time. Significant (p < 0.01) positive relationships were recorded between the age of the fetus and Se concentrations in the allantoic fluid (r = 0.57–0.75), fetal liver (r = 0.43–0.59) and kidney (r = 0.80–0.81) in both sheep and goats. A significant (p < 0.05) positive relationships were also recorded between the Se concentrations in the allantoic fluid and fetal liver (r = 0.35–0.37), the maternal plasma and liver Se concentrations (r = 0.37–0.57) between sheep and goats. A significant (p < 0.05) negative correlation was recorded between the Se concentrations in the allantoic fluid with maternal plasma of sheep (r = −0.41) as well as between the fetal liver and maternal liver Se (r = −0.22 to 0.50) and a negative correlation (r = −0.42 to 0.43) (p < 0.01) between Se concentrations in the fetal liver and amniotic fluid in both sheep and goats, respectively. Se concentration in the fetal liver was significantly (p < 0.01) higher than that of the kidney and thyroid. In the thyroid gland no morphological differences were noted. Strong fetal–maternal relationships in Se concentration were evident throughout the gestational period and dams seem to sacrifice Se levels in order to maintain that in the fetus. Se concentrations in the amniotic and allantoic fluids could be used as a possible indicator of the Se status of the fetus throughout gestation.     

Heat treatment of soybean meal and rapeseed meal suppresses rumen degradation of phytate phosphorus in sheep

The effect of heat treatment on rumen degradation of phytate in soybean meal and rapeseed meal was studied on three sheep fitted with rumen cannula. Soybean meal and rapeseed meal were roasted at 133°, 143° or 153°C for 3 h and the rumen degradation of phytate phosphorus in untreated and heat treated oilseed meals was examined using the nylon-bag technique. Effective degradability of phytate phosphorus in soybean and rapeseed meals, estimated at ruminal outflow rates of 0.02, 0.05 and 0.08 h⁻¹, was significantly (p < 0.05) reduced by heat treatment. The reduction was more marked in rapeseed meal than in soybean meal. These results suggest that heat processing of oilseed meals suppresses phytate degradation in the rumen and leads to a low availability of dietary phytate phosphorus.     

Effect of rumen ciliates on the digestive utilization of various carbohydrate-rich diets and on the end-products formed in the rumen. II. Utilization of inulin, saccharose and lactose

Three diets rich in inulin, saccharose and lactose, respectively, were given to 10 rumen-fistulated sheep. Two animals were defaunated, two were inoculated with either Polyplastron multivesibulatum or Entodinium sp., and two others were inoculated with both. The latter two were bred in conventional conditions. All animals ingested the same amounts of carbohydrates in the three diets (21-22 g/kg P0.75/day). Dietary nitrogen content was similar (table 1). The ciliate population was improved with the inulin diet (fig. 1; table 2). With a mixed population, the Entodinium improved with the inulin diet (fig 1; table 2). With a mixed population, the Entodinium sp. genus was always predominant. Holotrich protozoa (mainly Isotricha) in the rumen of the conventional sheep represented 15 to 30% of the total ciliate biomass, indicating that they were able to metabolize these soluble sugars. We also observed that P. multivesiculatum can ferment cellulose and all the soluble carbohydrates proposed in these diets. However, Entodinium sp. development occurred mainly in the presence of the sugard produced during carbohydrate hydrolysis by other ciliates or bacteria. The highest organic matter digestibility, noted in faunated animals (table 3) was confirmed by the VFA concentration in the rumen (table 4). This could be explained either by an activation of bacterial metabolism due to predation or by the direct effect of ciliates on fermentations, or both. Modifications in the VFA composition varied with ciliate inoculation, showing that ciliate metabolism may vary with the nature of the energy in the diet or that the observed results depended on various opposite effects in which the intensity of each component was influenced by the diet. In general, the acetic acid molar proportion increased and propionic acid decreased when there was a considerable Entodinium sp. population. The effect on butyric acid was low with these diets. Higher ammonia and lactic acid concentrations were observed in the rumen of faunated than defaunated sheep, irrespective of the ciliate inoculum.