Identification and phylogenetic analysis of Babesia parasites in domestic dogs in Nigeria

The present study examined the presence of Babesia parasites in 104 domestic dogs in Nigeria. Sequentially, Babesia parasites infecting domestic dogs underwent genetic and phylogenetic analyses. The results of nested PCR based on the Piroplasmida 18S rRNA gene illustrated that 13.5% (14/104) of the samples were positive. The obtained positive samples determined the nucleotide sequences of the 18S rRNA genes. In the genetic and phylogenetic analyses, four of five nucleotide sequences were similar to Babesia canis rossi, and one sample exhibited a close similarity to a Babesia sp. isolated from a raccoon in Hokkaido, Japan. The present study revealed the widespread presence of B. canis rossi among domestic dogs in Nigeria.     

Numbers of nitrate-reducing bacteria in the rumen as estimated by competitive polymerase chain reaction

Cell numbers of known species of nitrate- and nitrite-reducing bacteria, Selenomonas ruminantium, Veillonella parvula and Wollinella succinogenes , in the rumen of goats (25–30 kg) were estimated by competitive polymerase chain reaction (PCR). The number of S. ruminantium was the largest of the three species examined, and tended to be greater in goats fed a high-concentrate diet (5.6 × 10⁷ cells/mL rumen fluid) than in goats fed a high-roughage diet (1.3 × 10⁷ cells/mL). The number of V. parvula tended to be greater when goats were fed a high-roughage diet (6.7 × 10³/mL) than when fed a high-concentrate diet (3.2 × 10³/mL). The number of W. succinogenes was below the detectable level (< 1.0 × 10²/mL) when a high-concentrate diet was fed, but was significantly increased by feeding a high-roughage diet (1.6 × 10³/mL). Addition of potassium nitrate (6 g/day) to the high-concentrate diet tended to increase V. parvula , and significantly increased W. succinogenes , indicating that these two bacteria can be increased by feeding a diet containing nitrate.     

Ability to utilize lactate and related enzymes of a ruminal bacterium, Selenomonas ruminantium

The ability of a nitrate‐reducing and nitrite‐reducing strain of Selenomonas ruminantium ssp. lactilytica (TH1) to utilize lactate was examined at the cell and enzyme levels. The TH1 strain was found to possess NAD‐independent D‐lactate dehydrogenase (iD‐LDH), with little or no lactate racemase or L‐lactate dehydrogenase, implying that TH1 virtually utilizes only the D‐form of lactate. Therefore, the introduction of lactate racemase to TH1 may enhance its ability to utilize lactate in the rumen where both D‐lactate and L‐lactate are produced. Because lactate utilization by Megasphaera elsdenii in the rumen may increase methanogenesis, it is desirable to increase lactate utilization by S. ruminantium, which may decrease methanogenesis. However, the specific activity of iD‐LDH, which represents the amount of enzyme per cell, in TH1 was approximately threefold lower than M. elsdenii. Properties of iD‐LDH, such as optimal pH and temperature, affinity for D‐lactate, and effect of metal ions, did not differ greatly between TH1 and M. elsdenii. The specific activity of iD‐LDH in TH1 increased as the D‐lactate concentration in the medium increased, suggesting that iD‐LDH synthesis is regulated in response to D‐lactate. On the contrary, no iD‐LDH activity was detected when TH1 was grown in the presence of glucose, even when D‐lactate was present. This result suggests that iD‐LDH synthesis is strongly suppressed by glucose. In order to improve the ability of S. ruminantium to utilize lactate and reduce nitrate and nitrite, it is important to enhance iD‐LDH synthesis in addition to the introduction of lactate racemase.     

Number of nitrate- and nitrite-reducing Selenomonas ruminantium in the rumen, and possible factors affecting its growth

The cell number of Selenomonas ruminantium (S. ruminantium) that reduces nitrate and nitrite in the rumen was usually 8–10% of the total number of S. ruminantium (an order of 10⁶/mL). The percentage was not affected by the roughage/concentrate ratio or nitrate content of the diet in 2 weeks. However, feeding a high‐nitrate diet for 12 weeks increased the percentage. The percentage of lactate‐using S. ruminantium, such as the ssp. lactilytica, was less than 1% of the total number of S. ruminantium. No S. ruminantium was found that used formate as an electron donor for nitrate and nitrite reduction. Lactate and H₂ appeared to be important for nitrate and nitrite reduction by S. ruminantium. Nitrate reduction by S. ruminantium was enhanced by the coexistence of amylolytic bacteria in a medium containing starch, and as a result, nitrite accumulation increased. Coexistence of cellulolytic bacteria facilitated the growth of S. ruminantium in a medium containing cellulose, and consequently increased nitrite reduction. In order to suppress nitrite accumulation in the rumen, it may be important to enhance fiber digestion.     

Laparoscopic cryptorchidectomy in standing bulls

Laparoscopic cryptorchidectomy without insufflation was applied in 10 standing bulls aged 3 to 15 months. Nine bulls were preoperatively pointed out intra-abdominal testes by computed tomography. Preoperative fasting for a minimum of 24 hr provided laparoscopic visualization of intra-abdominal area from the kidney to the inguinal region. Surgical procedure was interrupted by intra-abdominal fat and testis size. It took 0.6 to 1.5 hr in 4 animals weighing 98 to 139 kg, 0.8 to 2.8 hr in 4 animals weighing 170 to 187 kg, and 3 and 4 hr in 2 animals weighing 244 and 300 kg to complete the cryptorchidectomy. In conclusion, standing gasless laparoscopic cryptorchidectomy seems to be most suitable for bulls weighing from 100 to 180 kg.     

Short-term evaluation of oxygen transfer from rice (Oryza sativa) to mixed planted drought-adapted upland crops under hydroponic culture

Mixed cropping is a cultivation method widely practiced in tropical regions. The newly developed close mixed planting technique mitigates the flood stress of drought-adapted upland cereal species by co-growing rice (Oryza sativa) plants under field flood conditions. We tested the hypothesis that O₂ was transferred from rice to upland crops using the model system of hydroponic culture. To confirm the hypothesis, the phenomena of O₂ absorption and release by plants were evaluated in a water culture condition without soil. Experiments were conducted in a climate chamber to estimate the amount of O₂ released from the roots of rice and pearl millet (Pennisetum glaucum) under both O₂-rich (20.0 ± .0% conc. in phase I) and O₂-free dark (.8 ± .0% conc. in phase II) conditions. The total O₂ change (between the two phases) in a single planting of rice and pearl millet was significantly higher than that of the mixed planting of rice and pearl millet, which indicated that O₂ was transferred from rice to pearl millet under a water culture condition. The result indicated that approximately 7 μM O₂ g fresh root weight^?1 h^?1 was transferred between the two plant species. O₂ transfer was confirmed between the two plant species in a mix cultured in water, implying its contribution to the phenomenon that improved the physiological status of drought-adapted upland crops under field flood conditions.     

Effect of ethanol on nitrate and nitrite reduction and methanogenesis in the ruminal microbiota

The effect of ethanol on nitrate and nitrite reduction was examined by conducting in vitro experiments with mixed ruminal microbes. The addition of ethanol to cultures of mixed ruminal microbes stimulated nitrate reduction, and, to a greater extent, nitrite reduction, which resulted in a decrease in nitrite accumulation. However, known nitrate‐reducing ruminal bacteria, such as Selenomonas ruminantium, Veillonella parvula and Wolinella succinogenes, were unable to utilize ethanol directly as an electron donor for nitrate reduction. No nitrate‐reducing bacterium capable of utilizing ethanol was found in the rumen of goats. However, when mixed ethanol‐utilizing, hydrogen gas (H₂)‐producing bacteria (Ruminococcus albus and Ruminococcus flavefaciens) were added to the culture of the mixed nitrate‐reducing bacteria described above, nitrate and nitrite reduction was observed. These results suggest that the nitrate‐reducing bacteria utilized the H₂ that was produced from ethanol oxidation by the ethanol‐utilizing bacteria as an electron donor. It is conceivable that the stimulation of nitrate and nitrite reduction by ethanol, observed in the culture of mixed ruminal microbes, was a result of electron transfer from ethanol to nitrate, and nitrite through H₂, that is, ‘interspecies hydrogen transfer’ from ethanol‐metabolizing bacteria to nitrate‐reducing bacteria. Thus, the addition of ethanol to high‐nitrate diets may be effective for preventing nitrate poisoning. Furthermore, methane production was reduced to less than one‐third by the addition of mixed nitrate‐reducing bacteria to the co‐culture of mixed methanogens with mixed ethanol‐utilizing bacteria incubated in a medium containing ethanol and nitrate. Therefore, the addition of ethanol and nitrate may decrease methanogenesis without suppressing overall fermentation in the rumen.