Fungal Zoospores Research Articles

Rumen microbes and microbial protein synthesis in Thai native beef cattle fed with feed blocks supplemented with a urea–calcium sulphate mixture

The influence ofslow-release urea (urea–calcium sulphate mixture; U–CaS) in feed blocks on rumen micro-organisms, predominant cellulolytic bacteria, microbial protein synthesis and ecology was studied in Thai native beef cattle. Four animals with an initial body weight of 100 ± 3.0 kg were randomly assigned to a 4 × 4 Latin square design with four dietary treatments (U–CaS in iso-nitrogen feed blocks at 0, 120, 150 and 180 g/kg dry matter (DM), respectively; U–CaS replaced urea). After 21 days of experimental feeding, rumen fluid was collected at 0 and 4 h after feeding. The mean intake of feed blocks and other feedstuffs offered (rice straw and concentrates) amounted to 0.3, 2.3 and 0.6 kg DM/day, respectively. Inclusion of U–CaS did not altered pH and temperature in the rumen. However, ruminal NH3–N concentration decreased quadratically (p < 0.05) in response to U–CaS inclusion, with the lowest value at 180 g U–CaS per kg feed block. With inclusion of U–CaS, the populations of rumen bacteria increased quadratically (p < 0.05) and counts of fungal zoospores were linearly enhanced (p < 0.05), being highest at 180 g U–CaS per kg feed block. Supplementation of U–CaS increased the concentration of total bacteria linearly (p < 0.05) and of Fibrobacter succinogenes quadratically (p < 0.05), whereas Ruminococcus flavefaciens and Ruminococcus albus were not affected by dietary treatments. Microbial crude protein yield and efficiency of microbial nitrogen (N) synthesis were linearly increased with different levels of U–CaS addition. Furthermore, current data clearly indicate that inclusion of U–CaS in feed blocks can affect micro-organism diversity and major cellulolytic bacteria.

Can fungal zoospores be the source of energy for the rumen protozoa Eudiplodinium maggii?

Results of our earlier studies showed the ability of ciliates Eudiplodinium maggii to digest and metabolize commercial chitin. The natural source of this polysaccharide in the rumen are fungi. The objectives of present research were to determine the effect of fungal zoospores on the survival and population density of E. maggii to quantify the concentration of chitin in the cells of protozoa and to examine the ability of E. maggii, to ferment chitin of fungal zoospores. The cultivation experiment showed that the survival of protozoa was shorter than 4 days when the culture medium was composed of buffer solution and lyophilized fungal spores. An enrichment of this medium with wheat gluten prolonged the survival of ciliates up to 8 days. The supplementation of the last medium with meadow hay enabled the protozoa to survive for 28 days but a positive effect was observed only during the last 8 days of experiment. The chitin content was 0.27 ng and 0.21–0.35 ng per single zoospore and ciliate, respectively. An increase in the concentration of volatile fatty acids (VFA) was found when protozoa were incubated with zoospores. The production rate of VFA was 46.3 pM/protozoan per h whereas the endogenous production did not exceed 31 pM/protozoan per h. The molar proportion of acetic acid was 77.7% and these of butyric and propionic acids–12.2 and 11.0%, respectively. The obtained results make it evident that carbohydrates present in fungal zoospores were utilized by protozoa in energy yielding processes.

Effects of plant herb combination supplementation on rumen fermentation and nutrient digestibility in beef cattle.

Four rumen-fistulated crossbred beef cattle (Brahman native) were randomly assigned according to a 4×4 Latin square design experiment to be fed plant herb supplements in their concentrate mixture. The treatments were: without herb supplementation (Control), lemongrass meal supplementation at 100 g/d (L), lemongrass meal supplementation at 100 g/d plus peppermint powder at 10 g/d (LP), and lemongrass meal supplementation at 100 g/d plus peppermint powder at 10 g/d with garlic powder 40 g/d (LPG), respectively. Based on the present study, the DMI and apparent digestibility of DM, OM, aNDF and ADF were not affected by dietary herb supplementation while CP digestibility tended to be decreased by herb supplement. Moreover, NH3-N and BUN were decreased in all herb supplemented treatments and there was a tendency to an increase in ruminal pH in all herb supplemented groups. While there was no change in TVFA and C4 among lemongrass treatments, C2 was decreased in all herb supplemented treatments while C3 was increased. Methane production by calculation was the lowest in the LP and LPG groups. Population sizes of bacteria and protozoa were decreased in all herb supplemented groups, but not fungal zoospores. In all supplemented groups, total viable and proteolytic bacteria were decreased, while amylolytic and cellulolytic bacteria were similar. More importantly, in all herb supplemented groups, there were higher N balances, while there was no difference among treatments on purine derivative (PD) excretion or microbial N. Based on the results above, it could be concluded that there was no negative effect on ruminal fermentation characteristics and nutrient utilization by plant herb supplement, but protozoal population and CH4 production were reduced. Thus, lemongrass alone or in combination with peppermint and garlic powder could be used as feed additives to improve rumen fermentation efficiency.

Saprolegniasis in Freshwater Catfishes Sold in Fish Markets in Asaba, Southern Nigeria

The prevalence of saprolegniasis in freshwater catfishes sold in fish markets in Asaba was investigated. Two hundred and sixty-five freshly caught table-sized freshwater catfishes namely: Clarias anguillaris (Pellegrin), Heterobranchus bidorsalis (Geoffrey St. Hilaire), Synodontis clarias (Linnaeus), Schilbe mystus (Linnaeus) and Bagrus bayad (Ruppell) were used for the study which lasted for three months. Fish samples bought on a weekly basis from two major markets (Ogbeogonogo and Cable point) were transported to the laboratory and examined by smear scrapping of mucus on skin of fish for saprolegniasis and possible secondary bacterial and protozoal infections using routine procedures. Isolates from cultures revealed the presence of saprolegniasis, scyphidian flora and bacterial infections of Staphylococcus aureus and Escherichia coil. Out of 265 catfishes examined, 46 (17.4%) had saprolegniasis. This prevalence of infection was not significant (P >0.05). The number of fungal zoospores from saprolegniasis ulcerative lesion was however significantly (P < 0.05) higher than those of the control which were free from Saprolegnia infection. A significant (P<0. 05) number, 25 (54%) of Saprolegnia infected catfishes had scyphidian flora. S. aureus was isolated from all catfishes examined while E. coli was found in 193 (72.8%) of the fishes. Fish culturist and fresh fish handlers should maintain good water quality for cultured fishes and a high standard of personal hygiene to avoid the health implications of fish diseases.

A novel subtilisin-like serine protease of Batrachochytrium dendrobatidis is induced by thyroid hormone and degrades antimicrobial peptides

Batrachochytrium dendrobatidis (B. dendrobatidis), a chytrid fungus, is one of the major contributors to the global amphibian decline. The fungus infects both tadpoles and adult amphibians. Tadpoles are infected in their keratinized mouthparts, and infected adults exhibit hyperkeratosis and loss of righting reflex. Infections of adults may result in death from cardiac arrest in susceptible species. Thyroid hormone plays a key role in amphibian metamorphosis. The occurrence of B. dendrobatidis in tadpoles during metamorphosis may result in exposure of the fungus to host morphogens including TH. This exposure may induce gene expression in the fungus contributing to invasion and colonization of the host. Here, we demonstrate movement of fungal zoospores toward TH. Additionally, expression of a subtilisin-like serine protease is up-regulated in B. dendrobatidis cells exposed to TH. A gene encoding this protease was cloned from B. dendrobatidis and expressed in Escherichia coli. The protein was partially purified and characterized. The similarity between subtilases of human dermatophytes and the B. dendrobatidis subtilisin-like serine protease suggests the importance of this enzyme in B. dendrobatidis pathogenicity. Cleavage of frog skin antimicrobial peptides (AMPs) by this B. dendrobatidis subtilisin-like serine protease suggests a role for this enzyme in fungal survival and colonization.

English

This experiment was conducted to investigate the effect of urea and urea-calcium hydroxide treated rice straws on feed intake, rumen fermentation and milk production in lactating dairy cows. Three multiparous Holstein crossbred dairy cows, mid-lactation with 365 ± 30 kg BW, were randomly assigned to receive three kinds of rice straw according to 3 × 3 Latin square design: untreated (T1), 2 × 2% urea-calcium hydroxide treated (T2) and 3% urea treated (T3). Based on the present findings, urea-calcium hydroxide could enhance the nutritive value of rice straw. In addition, dry matter intake (DMI) and nutrient digestibility (DM, CP, OM, NDF and ADF) were significantly increased by straw treatments (P 0.05). Ruminal NH3-N concentration was increased in both treated straw groups while BUN was similar. While TVFA and C3 were improved in cows receiving urea and urea-calcium hydroxide treated rice straw, C2 and C4 remained stable. Furthermore, total bacterial and fungal zoospores were higher in the treated groups, while protozoa were not different. Ruminal viable bacterial groups were higher in the urea and urea-calcium hydroxide treated, except for proteolytic bacteria. Cows received treated rice straw consumed more N intake as well as N absorption (P < 0.05). Remarkably, the PD, microbial protein and EMPS were enhanced by treated straw. Urea-calcium hydroxide treated rice straw significantly (P < 0.05) increased milk yield and milk compositions. Based on this study, either 2 + 2% urea-calcium hydroxide or 3% urea treated rice straw could be fed to lactating dairy cows as for improvement of feed intake, nutrient digestibility, rumen fermentation and milk production, thus be recommended for use by dairy farmers. Key words: Rice straw, urea, Calcium hydroxide, rumen fermentation, milk production, dairy cow.

Effects of Leucaena leaf pellet on bacterial diversity and microbial protein synthesis in swamp buffalo fed on rice straw

The experiment was conducted to determine the effect of Leucaena leaf pellet (LLP) supplementation on feed intake, microbial protein synthesis and rumen microbial population and diversity in swamp buffalo fed on rice straw. Four swamp buffalo bulls were randomly assigned according to a 4×4 Latin square design to receive LLP at 0, 150, 300 and 450g/hd/d. Untreated rice straw was fed ad libitum, while concentrate was fed at 5g/kg BW. The results revealed that rice straw intake and total intake were significantly improved when level of LLP supplementation increased. Ruminal NH3–N concentration was significantly higher than in the control group. Population of fungal zoospores, amylolytic bacteria, proteolytic bacteria and cellulolytic bacteria were significantly increased (P<0.05) with increasing LLP supplementation while the population of rumen protozoa decreased. Supplementation of LLP increased the population of total bacteria, Ruminococcus albus, Fibrobacter succinogenes, and Ruminococcus flavefaciens, while population of methanogenic bacteria were decreased (P<0.05). The N balance and microbial nitrogen supply were remarkably improved when LLP supplementation level increased. Rumen methanogen diversity was not shifted as analyzed by PCR-DGGE technique, while rumen total bacterial diversity was similar by sampling time and treatments. Supplementation of LLP can improved rumen ecology, thus improved N-retention and microbial N supply.

Effects of Protein Level and Mangosteen Peel Pellets (Mago-pel) in Concentrate Diets on Rumen Fermentation and Milk Production in Lactating Dairy Crossbreds.

Four, lactating dairy crossbreds (50%×50% Holstein Friesian×Native Zebu cattle) were randomly assigned according to a 2×2 factorial arrangement (two protein levels and two levels of mangosteen peel pellets (Mago-pel)) in a 4×4 Latin square design to receive four dietary treatments. All cows received concentrate at a proportion of 1 kg concentrate per 2 kg of milk yield, and urea-treated 5% rice straw (UTRS) was given ad libitum. It was found that total dry matter intakes, nutrient digestibility, ruminal pH and NH3-N concentrations were not affected (p>0.05) by treatments. Concentrations of ruminal pH and NH3-N were not affected by dietary treatments although the concentration of BUN varied significantly (p<0.05) between protein levels (p<0.05). The populations of rumen bacteria and fungal zoospores did not differ among treatments (p>0.05); however, the population of protozoa was decreased (p<0.05) when cows received Mago-pel supplementation. The composition of the population of bacteria, identified by real-time PCR technique, including total bacteria, methanogens, Fibrobacter succinogenes and Ruminococcus albus was similar (p>0.05) among dietary treatments (p>0.05); however, copy numbers of Ruminococcus flavefaciens was increased when protein level increased (p<0.05). Microbial protein synthesis, in terms of both quantity and efficiency, was enriched by Mago-pel supplementation. Milk yield was greatest in cows fed UTRS based diets with concentrate containing protein at 16% CP with Mago-pel, but were lowest without Mago-pel (p<0.05). In addition, protein level and supplementation of Mago-pel did not affect (p>0.05) milk composition except solids-not-fat which was higher in cows fed the diet with 19% CP. Therefore, feeding a concentrate containing 16% CP together with 300 g/hd/d Mago-pel supplementation results in changes in rumen fermentation and microbial population and improvements in milk production in lactating dairy crossbreds fed on UTRS.

Effect of eucalyptus (Camaldulensis) leaf meal powder on rumen fermentation characteristics in cattle fed on rice straw

Three, Holstein Friesian, non-lactation crossbred dairy cows were used to evaluate the effect of Eucalyptus (Camaldulensis) leaf meal powder (EUCAP) supplementation on feed intake, digestibility and rumen fermentation. The animals were randomly assigned according to a 3 × 3 Latin square design using three levels of EUCAP supplementation (0, 100 and 200 g/hd/d) and offered rice straw ad libitum, together with concentrate at 0.5% body weight. The results revealed that voluntary feed intake (kg/hd/d) was significantly decreased when EUCAP was supplemented at 200 g/hd/d. Digestibility coefficient (%) of DM, OM, CP, NDF and ADF were similar among treatments. Ruminal temperature and pH were not affected by EUCAP supplementation. However, NH3-N and BUN concentrations were decreased when supplementation of EUCAP at 200 g/hd/d. Ruminal fungal zoospores were not significantly different among treatments, while protozoa, bacteria population by direct counts were significantly reduced with increasing supplementation levels of EUCAP. In addition, viable total bacteria, proteolytic bacteria and cellulolytic bacteria were decreased when EUCAP were supplemented at 100 and 200 g/hd/d while amylolytic bacteria was not different among treatments (P>0.05). Furthermore, total volatile fatty acid concentrations, proportion of acetate, acetate to propionate ratio were reduced with increasing level of supplementation, while, proportion of propionate increased. Methane production was reduced in supplemented treatments at 100 g/hd/d. Supplementation of EUCAP at 100 g/day for ruminants could be on alternative feed enhancer which reduces rumen methane gas production in cattle, while nutrient digestibilities were unchanged. Key words: Eucalyptus, rumen fermentation, rice straw, rumen manipulation, cows.

Effects of energy level and Leucaena leucocephala leaf meal as a protein source on rumen fermentation efficiency and digestibility in swamp buffalo

Four Thai – rumen fistulated male swamp buffaloes (Bubalus bubalis), about 3 years old with 360±18kg liveweight, were randomly assigned according to a 2×2 factorial arrangement in a 4×4 Latin square design to receive four dietary treatments. The treatments were as follows: a cassava based supplement (CS) at 1g/kg BW and Leucaena leucocephala leaf meal (LLM) at 300g/d (T1); CS at 2g/kg BW with LLM at 300g/d (T2); CS at 1g/kg BW and heat treated LLM (HLLM) at 300g/d (T3); and CS at 2g/kg BW and HLLM at 300g/d. During the experiment, urea–calcium hydroxide treated rice straw was given on ad libitum basis. The results revealed an increase in roughage and total dry matter (DM) intake (P<0.05) by CS at 2g/kg BW (T2 and T4) as compared with CS at 1g/kg BW (T1 and T3). Digestion coefficients of DM, organic matter (OM), and crude protein (CP) were increased by CS at 2g/kg BW, while neutral detergent fiber (aNDF) and acid detergent fiber (ADF) were similar among treatments. However, there was no effect of neither energy level nor HLLM on ruminal pH and temperature (P>0.05). Concentration of ruminal ammonia nitrogen (NH3-N) was decreased by HLLM as compared with LLM (P<0.05), while blood urea–nitrogen was not altered. There was an increase (P<0.05) in total volatile fatty acid (TVFA), acetic acid (C2), propionic acid (C3), and butyric acid (C4) concentrations and the highest were found in CS at 2g/kg BW with HLLM (T4), while the lowest was in T1 and T3. However, no changes in C2–C3 ratio were found in this study. Total bacterial direct counts were found different (P<0.05), whereas fungal zoospores and protozoal populations were similar among treatments. Nevertheless, viable bacterial counts were found affected by both concentrate level and HLLM. The treatments with HLLM were lower than those in LLM and CS at 2g/kg BW were higher than those supplemented at CS at 1g/kg BW (P<0.05). In addition, efficiency of rumen microbial CP synthesis tended to be higher in treatment with higher level of energy and HLLM. Based on this study, it could be concluded that LLM could be used as a protein source, while the combination of HLLM and CS at 2g/kg BW could enhance the voluntary feed intake, nutrient digestibility and rumen fermentation in swamp buffalo fed on treated rice straw (urea–calcium hydroxide treatment).

Level of crude protein in concentrate supplements influenced rumen characteristics, microbial protein synthesis and digestibility in swamp buffaloes (Bubalus bubalis)

The objective of this research was to evaluate the effect of level of CP in concentrate on rumen fermentation, microbial population (bacteria, protozoa, and fungi), microbial protein synthesis, feed intake and feed digestibility in swamp buffaloes (Bubalus bubalis) fed on rice straw based diet. Four, rumen-fistulated 4-year old swamp buffaloes with 381±10kg liveweight were randomly assigned to receive four dietary treatments according to a 4×4 Latin square design. Four levels of crude protein (92, 124, 181 and 219g/kg CP) in concentrate mixture were fed at 1g/kg body weight (BW) and rice straw was fed ad libitum. The study revealed that dry matter intake, apparent digestibility of DM, OM, CP and NDF, were significantly higher in buffaloes fed with higher CP level especially at the 124–181g/kg CP level, while, ADF digestibilities were not affected. Level of CP supplementation had affected on rumen pH, NH3N and blood urea N (P<0.01). Meanwhile, rumen propionic acid production was significantly higher at 181g/kg CP level, while total fatty acids (VFA), acetic acid, butylic acid and C2:C3 ratio, were similar among treatments. However, protozoal and fungal zoospore populations were not changed while bacterial populations were significantly different among treatments and were higher with high level of CP. Furthermore, application of quantitative PCR to quantify predominant cellulolytic bacteria (16S rRNA) targets revealed that treatments did not change population of Ruminococcus flavefaciens bacteria (P>0.05) and methanogenic bacteria (P>0.05). Meanwhile, total bacteria (P<0.05), Fibrobacter succinogenes (P<0.05) and Ruminococcus albus (P<0.01) population were significantly increased when CP was at a higher level. Moreover, PD excretion, PD absorption, N absorption, N retention, MNS and EMPS were significantly increased. Therefore, based on this study, it could be concluded that level of CP between 124 and 181g/kg CP in the concentrate supplement revealed the highest rumen fermentation efficiency in swamp buffaloes fed on rice straw.

Supplementation Levels of Palm Oil in Yeast (Saccharomyces cerevisiae) Culture Fermented Cassava Pulp on Rumen Fermentation and Average Daily Gain in Crossbred Native Cattle

Nine, two-years old of crossbred native cattle were used to examine the effects of supplementation levels of palm oil in yeast culture fermented cassava pulp on rumen fermentation and average daily gain. The cows were randomly allocated in a complete randomized design and three replicates (animals) per treatment. The first group (control) was fed on a yeast fermented cassava pulp without palm oil (YFCP0), The second group was fed yeast fermented cassava pulp + palm oil at 1% (YFCP1)and third groups was fed yeast fermented cassava pulp + palm oil at 2% (YFCP2), respectively. The cows were offered the treatment diets at 2%BW and rice straw was fed ad libitum. The results have revealed that supplementation of dietary treatment on feed intake, ruminal pH, ammonia-nitrogen and blood urea nitrogen concentration were non- significantly different, while Average Daily Gain (ADG) and cost production were significantly different and had highest in cattle receiving YFCP2 than those fed YFCP1, YFCP0 diets (633.1, 614.5 and 511.1 g/day of ADG and 0.92, 0.81, 0.73 US$/kgBW of cost production, respectively). The populations of bacteria and fungal zoospores were significantly different as affected by levels of palm oil supplementation. Especially, supplementation of YFCP2 in cattle had highest increase populations of bacteria and fungi zoospore than those fed YFCP1 and YFCP0 but decreased protozoal populations. Therefore, supplementation levels of palm oil at 2% in Yeast Culture Fermented Cassava Pulp (YFCP1) as supplement diets with rice straw as roughage source could highest improved ruminal fermentation efficiency, average daily gain including increase populations of bacteria and fungi zoospores, but decreased protozoal populations in rumen of crossbred native cattle.

Enrichment Value of Yeast-malate Fermented Cassava Pulp and Cassava Hay as Protein Source Replace Soybean Meal in Concentrate on Rumen Ecology in Crossbred Native Cattle

The objectives of this study was to evaluate the influence supplementation levels of Yeast-Malate Fermented Cassava Pulp (YMFCP) replace soybean meal in concentrate on feed-intake, Average Dairy Gain (ADG), rumen ecology and blood metabolites in crossbred native cattle. Five, two years of female crossbred native cattles weighing at 250±10 kg were randomly assigned according to a 5 x 5 Latin square design. The dietary treatments were as follows: T1 = supplementation of YMFCP replace soybean ratio at 0:100%; T2 = supplementation of YMFCP replace soybean ratio at 25:75%; T3 = supplementation of YMFCP replace soybean ratio at 50:50%; T4 = supplementation of YMFCP replace soybean ratio at 75:25%, T5 = supplementation of YMFCP replace soybean ratio at 100:0%, respectively. The cows were offered the treatment concentrate at 1.0%BW. All cows were fed ad libitum of rice straw with water and a mineral salt block. The results have revealed that rumen fermentation, blood metabolites and average daily gain were significantly different for all treatments. The populations of protozoa and fungal zoospores were significantly different as affected by supplementation levels of Yeast-Malate Fermented Cassava Pulp (YMFCP) replace soybean meal in concentrate. Moreover, supplementation levels of Yeast-Malate Fermented Cassava Pulp (YMFCP) replace soybean meal ratio at 50:50% in concentrate with rice straw as roughage source could highest improved ruminal fermentation efficiency, average daily gain including increase populations of bacteria and fungi zoospores, but decreased protozoal populations in rumen of crossbred native cattle.

Supplementation of Cassava and Durian Hull Fermented Yeast (Saccharomyces cerevisiae) on Rumen Fermentation and Average Daily Gain in Crossbred Native Cattle

Ten, two-years old of crossbred native cattle weighing about at 250±20 kg were randomly divided into two groups according to receive two groups of supplemental dietary treatments by receiving YFCP1 + YFCP2 (T1) and YFCRR + YFDH (T2). The cows were offered the treatment diets at 2%BW and rice straw was fed ad li bitum. Means were compared using pair t-test. All animals were kept in individual pens and received free access to water. The results have revealed that supplementation of dietary treatment on feed intake was non-significantly different, while average daily gain (ADG) and rumen microorganisms especially bacteria and fungi zoospores were significant different and cattle in heifer fed YFCRR + YFDH (T2) treatments and received YFCP1 + YFCP2 (T1) (646.4 and 533.2 g/d). In addition, the ruminal pH, ammonia-nitrogen and blood urea nitrogen concentration were non-significantly different. Supplementation of T2 could improve population of bacteria and fungal zoospore higher than those fed T1, but decreased populations of Holotrich and Entodiniomorph protozoa in rumen. The results indicate that supplementation of yeast fermented cassava and durian hull as supplement diets with rice straw as roughage source could improve ruminal fermentation efficiency, average daily gain in crossbred native cattle.

Comparison of ruminal fermentation characteristics and microbial population in swamp buffalo and cattle

The aim of this study was to determine the ruminal cellulolytic bacterial population in swamp buffalo and beef cattle fed on rice straw by real-time PCR techniques. Four, rumen-fistulated swamp buffalo and four beef cattle (Native×Brahman) were randomly assigned to receive rice straw as a main feed with minimal amount of concentrate. All animals were allowed to adapt to feeds respective before samplings were conducted. It was found that diurnal ruminal pH and NH3–N concentration of buffalo were not different with those found in cattle, population of bacteria and fungal zoospores while the protozoal population were lower (P<0.05). In addition, the nutrient digestibilities of DM, OM, CP, NDF and ADF were found higher in buffalo than in cattle. Employing the real-time PCR techniques for the quantification of cellulolytic bacterial numbers (Ruminococcus albus) in the digesta of swamp buffalo, the results revealed significant higher in buffalo than those in cattle. However, at 4h post-feeding R. albus were significantly higher in buffalo than those in cattle measured in rumen fluid, while F. succinogenes resulted in higher number in cattle than those in buffalo. Interestingly, the values found in the digesta samples were higher in cellulolytic bacteria than those found in the rumen fluid. This finding indicates higher ability of swamp buffalo in digesting low-quality roughages, especially rice straw.

Effect of coconut oil and mangosteen peel supplementation on ruminal fermentation, microbial population, and microbial protein synthesis in swamp buffaloes

Four rumen fistulated swamp buffalo bulls were randomly assigned to receive dietary treatments according to a 4×4 Latin square design. The four dietary treatments were unsupplementation (control), supplementation with coconut oil (CO) at 50g/kg, supplementation with mangosteen peel (MP) at 30g/kg, and supplementation with CO at 50g/kg and MP at 30g/kg (COM), of total dry matter intake. Animals received concentrate at 10g/kg BW, together with a basal diet of ad libitum rice straw. Feed intake, digestibility of dry matter, organic matter and crude protein were not significantly affected; however, MP supplementation resulted in significantly lower overall NDF and ADF digestibility when compared with COM supplementation. Ruminal pH and BUN concentrations were not significantly different between treatments, while supplementation with CO increased concentration of ruminal NH3–N. Total volatile fatty acid concentrations were increased with MP supplementation. The proportion of ruminal acetic acid was decreased while propionic acid was increased by either CO or COM supplementation. The ruminal protozoal population was dramatically decreased with either CO or MP supplementation; whereas, COM treatment had a lower fungal zoospores population when compared with the control group. Supplementation with MP resulted in a lower population of cellulolytic bacteria than supplementation with COM. In addition, CO supplementation resulted in a higher population of proteolytic bacteria than the control or supplementation with COM. Nitrogen balance and microbial protein synthesis were not affected by CO or MP supplementation. In conclusion, CO or MP supplementation could improve rumen fermentation by positively affecting the ruminal on microbial population in swamp buffalo on rice straw diets.

Specific amino acids of Olive mild mosaic virus coat protein are involved in transmission by Olpidium brassicae

Transmission of Olive mild mosaic virus (OMMV) is facilitated by Olpidium brassicae (Wor.) Dang. An OMMV mutant (OMMVL11) containing two changes in the coat protein (CP), asparagine to tyrosine at position 189 and alanine to threonine at position 216, has been shown not to be Olpidium brassicae-transmissible owing to inefficient attachment of virions to zoospores. In this study, these amino acid changes were separately introduced into the OMMV genome through site-directed mutagenesis, and the asparagine-to-tyrosine change was shown to be largely responsible for the loss of transmission. Analysis of the structure of OMMV CP by comparative modelling approaches showed that this change is located in the interior of the virus particle and the alanine-to-threonine change is exposed on the surface. The asparagine-to-tyrosine change may indirectly affect attachment via changes in the conformation of viral CP subunits, altering the receptor binding site and thus preventing binding to the fungal zoospore.

Effects of various plant protein sources in high-quality feed block on feed intake, rumen fermentation, and microbial population in swamp buffalo

This study was designed to determine effect of various plant protein sources in high-quality feed block (HQFB) on feed intake, rumen fermentation, and microbial population in swamp buffalo. Four rumen-fistulated swamp buffaloes (Bubalus bubalis) were randomly assigned according to a 4 × 4 Latin square design. Four kinds of plant protein sources (coarse rice bran (CRB), cassava hay (CH), Phaseolus calcaratus hay, and mulberry hay (MH)) were mixed in the HQFB. HQFBs were allowed to be licked at free choice, and urea-lime-treated rice straw (ULRS) were fed ad libitum. It was found that bacterial population and fungal zoospores in CH-fed group tended to be higher than those in other groups. Moreover, protozoal population in CH, P. calcaratus hay, and MH were lower than those in CRB supplemented group (P < 0.05). Cellulolytic bacterial population was highest in CH-fed group while proteolytic bacteria population was highest in P. calcaratus hay-fed group (P < 0.05). CH-fed group had higher ULRS intake than those in other groups (P < 0.05). Nutrient digestibility of CP, NDF, and ADF in CH-fed group was significantly higher than those in other groups (P < 0.05). Total VFA was highest in CH-fed group (P < 0.05). N absorption was highest in CH-fed group (P < 0.05). Based on this study, it could be concluded that cassava hay, P. calcaratus hay, and mulberry hay are potential to be used as protein sources in the HQFBs especially cassava hay.

Effect of legume (Phaseolus calcaratus) hay supplementation on rumen microorganisms, fermentation and nutrient digestibility in swamp buffalo

The objective of this research was to evaluate the effect of Phaseolus calcaratus hay (PCH) supplementation on the intake, digestibility, rumen fermentation, microbial population (bacteria, protozoa, and fungi) and methane production in swamp buffaloes fed on rice straw based diet. Four, 2.5year old rumen fistulated male buffaloes were randomly assigned according to a 4×4 Latin square design. The treatments were level of PCH supplementation at 0, 300, 600 and 900g DM/hd/d as supplements. The PCH contained 18.3% crude protein (CP) and 2.8% condensed tannins (CT). All buffaloes were fed with rice straw ad libitum while additional concentrate (12.6% CP) was fed at 0.3% body weight (BW). The study revealed that PCH supplementation had no effect on rumen temperature, pH, NH3-N and blood urea N. Volatile fatty acid (VFAs), especially those of propionic acid and acetic acid concentrations in the rumen were maximized (P<0.05) at 600g/hd/d feeding level. However, concentrations of each VFA and the acetate to propionate ratio did not differ among treatments. Bacterial, protozoal and fungal zoospore populations were maximized (P<0.05) at the intermediate PCH feeding levels. Rumen methane gas production was decreased linearly (P<0.05) with increasing level of PCH supplementation. N utilization in the buffaloes differed among treatments, with PCH supplementation linearly increasing N retention and efficiency of microbial N supply. Furthermore, PCH supplementation linearly increased (P<0.05) in terms of total DM intake, apparent digestibility of CP and OM, while, DM, NDF and ADF digestibilities were not affected. Supplementation of PCH at 600g/hd/d was beneficial in swamp buffaloes fed rice straw as a basal roughage, as it resulted in increased DM intake, reduced protozoal and methane gas production in the rumen, increased N retention as well as efficiency of rumen microbial CP synthesis.

Roles of parasitic fungi in aquatic food webs: a theoretical approach

Summary 1. Parasites are ubiquitous in ecosystems, but their roles in material transfer are poorly understood. Fungal parasites in freshwater ecosystems are of major importance to small heterotrophic eukaryotes and consume large phytoplankton that are resistant to zooplankton grazing. 2. To evaluate their ecosystem-level effects, we developed a simple food web model that incorporates competition between small and large phytoplankton for nutrients, zooplankton grazing on small phytoplankton, fungal parasitism on large phytoplankton and includes a newly discovered trophic link from fungal zoospores to zooplankton (F-Z link). 3. Our model demonstrates the likely occurrence of an indirect mutualism between fungi and zooplankton, in which fungal parasitism increases zooplankton production by reducing the biomass of inedible large phytoplankton. Contradicting the expectation from a previous short-term experiment that the F-Z link may benefit zooplankton, the presence of the F-Z link can reduce material transfer from phytoplankton to zooplankton because of the negative effect of the indirect mutualism. The model indicates that high growth efficiency of fungi on host tissue and their high nutrient status for zooplankton are crucial for the F-Z link to increase zooplankton production. 4. The model also indicates that the contribution of material transfer via F-Z link to zooplankton increases with nutrient availability. Our results suggest that parasitic fungi may be a key player in material transfer, especially in eutrophic ecosystems.