Eugene H. Johnson

Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis

SUMMARY Ever since its first description in 1918, Dientamoeba fragilis has struggled to gain recognition as a significant pathogen. There is little justification for this neglect, however, since there exists a growing body of case reports from numerous countries around the world that have linked this protozoal parasite to clinical manifestations such as diarrhea, abdominal pain, flatulence, and anorexia. A number of studies have even incriminated D. fragilis as a cause of irritable bowel syndrome, allergic colitis, and diarrhea in human immunodeficiency virus patients. Although D. fragilis is most commonly identified using permanently stained fecal smears, recent advances in culturing techniques are simplifying as well as improving the ability of investigators to detect this organism. However, there are limitations in the use of cultures since they cannot be performed on fecal samples that have been fixed. Significant progress has been made in the biological classification of this organism, which originally was described as an ameba. Analyses of small-subunit rRNA gene sequences have clearly demonstrated its close relationship to Histomonas, and it is now known to be a trichomonad. How the organism is transmitted remains a mystery, although there is some evidence that D. fragilis might be transmitted via the ova of the pinworm, Enterobius vermicularis. Also, it remains to be answered whether the two distinct genotypes of D. fragilis recently identified represent organisms with differing virulence.

Effect of heat stress on respiratory rate, rectal temperature and blood chemistry in Omani and Australian Merino sheep

Abstract The effect of heat stress (HS) on changes in respiratory rate, rectal temperature and blood chemistry parameters were evaluated in mature black wooly Omani and white wooly Australian Merino wethers. These animals were subjected to cool environment when the mean temperature humidity index (THI) was 72±1.4 (dry bulb temperature of 22.2–24.4xa0°C and relative humidity of 100–60%) during the month of December. This experiment was repeated during the hotter month of July of the following year, when the mean THI was 93±3.1 (dry bulb temperature of 35.6–43.9xa0°C and relative humidity 95–35%). Blood pH, bicarbonate (HCO 3 − ; mmol/l), creatinine (CR; μmol/l), respiratory rate and rectal temperature increased ( P 2 (kPa), base excess (BE; mmol/l), plasma calcium (Ca; mmol/l), creatinine phosphokinase (CPK; IU/l) and aspartate aminotransferase (AST; IU/l) decreased ( P P 2 (kPa), oxygen saturation (O 2 SAT; %) and blood urea nitrogen (BUN; mmol/l) in Omani sheep, but decreased ( P P P P P P

Effect of heat stress on milk production, rectal temperature, respiratory rate and blood chemistry in Holstein, Jersey and Australian milking Zebu cows

The effect of heat stress on changes in milk production, rectal temperature, respiratory rate and blood chemistry was evaluated in three groups of six mature Holstein, Jersey and Australian Milking Zebu (AMZ) dairy cows. These animals were subjected to a cool environment when the mean temperature–humidity index (THI) was 72±1.4 (dry bulb temperature of 22.2–24.4°C and relative humidity of 100–60%) during the month of December. This experiment was repeated during the hotter month of July of the following year, when the mean THI was 93±3.1 (dry bulb temperature of 35.6–43.9°C and relative humidity 95–35%). Holstein cows produced more (p<0.01) milk than AMZ and Jersey cows during the cooler months of the year and all the cows were dry during the hotter months from June until September. Heat stress increased (p<0.01) rectal temperature and respiratory rate in all three breeds. Heat stress had no effect on blood pH in Holstein and AMZ cows but lowered (p<0.01) blood pH from 7.42 to 7.34 in Jersey cows. In addition, heat stress lowered (p<0.01) blood pCO2 (kPa), bicarbonate (HCO3–, mmol/L), base excess (BE, mmol/L) and plasma chloride (Cl–, mmol/L) in all three breeds. The total haemoglobin (THb, g/dl) was elevated (p<0.01) in all three breeds when they were subjected to heat stress. Heat stress increased (p<0.01) oxygen saturation (O2SAT, %) in Jersey and AMZ cows but lowered it (p<0.01) in Holstein cows. On the other hand, heat stress increased (p<0.01) pO2 (kPa) in Holstein and Jersey cows but lowered it (p<0.01) in AMZ cows. Heat stress increased (p<0.01) plasma potassium (K, mmol/L) and calcium (Ca, mmol/L) only in Holstein and Jersey cows but lowered them (p<0.01) in AMZ cows. The plasma glucose (GLU, mmol/L) increased (p<0.01) with heat stress in Holstein and AMZ cows but decreased (p<0.01) in Jersey cows. Heat stress increased (p<0.01) plasma creatinine (CR, (mol/L) but lowered (p<0.01) plasma creatinine phosphokinase (CPK, IU/L), aspartate aminotransferase (AST, IU/L) and blood urea nitrogen (BUN, mmol/L) in all three breeds. These results indicate that heat-stressed Holstein and AMZ cows were able to maintain their acid–base balance with a marginal change in their pH of 0.02 when their rectal temperatures increased by 0.47 and 0.38°C, respectively. When heat stress increased the rectal temperature in Jersey cows by 0.70°C, the pH decreased (p<0.01) from 7.42 to 7.34. However, even with this decrease 0.08 the pH is still within the lower physiological limit of 7.31.

Effect of low levels of dietary cobalt on apparent nutrient digestibility in omani goats

Abstract The effect of low levels of dietary cobalt (Co) on apparent nutrient digestibility coefficients was investigated in three breeds of Omani goats (Batina, Dhofari and Jabal Akdhar). Goats were divided into control and treated groups. Goats in both groups were fed Rhodes grass hay ad libitum and a commercially prepared diet containing 0.10 and 0.12xa0mgxa0Co/kg dry matter, respectively, from 10 to 46 weeks. Animals in the treated group were supplemented with vitamin B 12 by giving sub-cutaneous injections of 2000xa0μg of hydroxocobalamin at week 10, and at 8 weeks intervals thereafter for 46 weeks. Serum vitamin B 12 levels were significantly higher ( P 12 for the control group dropped to levels consistent with those of lambs considered to have a deficiency of vitamin B 12 . Digestibility was determined on weeks 22, 26, 30 and 34. There were significant increases ( P 12 -treated group. Compared to the Jabal Akdhar and Dhofari goats, the treated Batina goats had the largest differences in digestibility coefficients between the treated and control animals. The results of this study showed that low levels of dietary cobalt in goats resulted in lowering the apparent nutrient digestibility coefficients compared to goats supplemented with vitamin B 12 . This is possibly due to several factors, including a reduction in rumen microorganisms, decrease in intestinal absorption of nutrients, and inadequate synthesis of the vitamin B 12 -dependent methylmalonyl co-enzyme A mutase and methionine synthase, the two enzymes essential for protein and energy metabolism.

Confirmation of the prophylactic value of paromomycin in a natural outbreak of caprine cryptosporidiosis

E.H. Johnson*, J.J.Windsor, D.E. Muirhead, G.J. King and R. Al-Busaidy Department of Animal and Veterinary Sciences, College of Agriculture, Department of Microbiology and Immunology, and Department of Pathology, College of Medicine, Sultan Qaboos University, Muscat; Veterinary Services, Diwan of Royal Court, Seeb Airport, Muscat, Sultanate of Oman *Correspondence: Department of Animal and Veterinary Sciences, College of Agriculture, Sultan Qaboos University, POBox 34, Al-Khod 123, Muscat, Sultanate of Oman. E-mail: ejohnson@squ.edu.om

Comparative effect of low levels of dietary cobalt and parenteral injection of vitamin B12 on carcass and meat quality characteristics in Omani goats

The effect of low levels of dietary cobalt (Co) on carcass and meat quality characteristics were investigated in 36 male goats of three different Omani breeds namely Batina, Dhofari and Jabal Akdhar. Goats were randomly divided into two groups at 10 weeks of age, control (18 animals) and treated (18 animals). Goats from both groups were fed Rhodesgrass hay and a commercially prepared diet containing 0.10 and 0.12 mg Co/kg DM, respectively from 10 to 46 weeks of age. Animals in the treated group were supplemented with subcutaneous injections of 2000 μg of hydroxocobalamin (vitamin B(12)) on week 10 and thereafter for 46 weeks at 8-week intervals. At 46 weeks of age, the animals were slaughtered and their carcass and meat quality characteristics compared. Serum vitamin B(12) levels were significantly higher in goats from the treated group from week 16 till the end of the experiment. The final live and carcass weights were significantly higher (P<0.05) for the treated Batina group by 13.4 and 8.3% compared with the control group, respectively. Shoulder, rack, loin and leg cut weights were also significantly higher (P<0.05) for the Batina treated group compared with the control group by 14.7, 16.8, 12.8 and 13.1%, respectively. Carcass length, leg length, width behind shoulder, maximum shoulder width and longissimus muscle area were significantly higher (P<0.05) for the Batina treated breed than for the control group by 6.7, 5.8, 10.1, 10.1 and 28.5%, respectively. Four muscles (Mm. longissimus dorsi, biceps femoris, semimembranosus, and semitendinosus) from treated and control groups were evaluated for ultimate pH, expressed juice, cooking loss%, colour (L*, a* and b*), and Warner-Bratzler shear force values. There were significant treatment effects on these muscle quality characteristics for the Batina breed only. Muscles from the treated group showed significantly lower (P<0.05) shear force values of between 15 and 27% than those from the control group. Moreover, the treated Batina goats tended to have significantly lower (P<0.05) ultimate pH, expressed juice, L* and higher a* values than those from the control group for longissimus dorsi and biceps femoris muscles only.

Serological evidence of caprine arthritis–encephalitis virus (CAEV) infection in indigenous goats in the Sultanate of Oman

Caprine arthritis encephalitis (CAE) is a chronic debilitating disease of goats caused by a lentivirus responsible for economic losses as a result of a drop in milk production and weight loss. The objective of the study was to determine if indigenous goats from five different regions in the Sultanate of Oman exhibit serological evidence of exposure to CAEV using a competitive-inhibition ELISA technique. Blood samples were collected from slaughtered goats (Nu2009=u20091,110) and from the National Serum Bank (nu2009=u2009528). In total, 83 (5.1%) of screened samples were classed as seropositive. The results provide the first serological evidence for the presence of CAEV in Oman.

Serum vitamin B12 levels in Omani goats.

Blood and faecal samples were studied from 200 Omani goats of both sexes and various age groups, within five different regions in Oman. Survey questionnaires were undertaken on each goat. The serum vitamin B12 values ranged from 105 to >2000 pg/ml, with a mean value of 723.1 pg/ml and a 95% confidence interval of 61–1507 pg/ml. Kids in the age group 1–3 months showed significantly lower levels of serum vitamin B12 than the older animals. Varying levels of serum vitamin B12 were found in different regions of Oman and on farms within the same region. Goats maintained on commercial feed showed higher levels of serum vitamin B12 than those maintained on pasture or fed on household leftover food, as commonly practised in Oman. Coccidial counts were highest in animals with lower levels of serum vitamin B12. The results of this study indicate that there is a wide range of serum vitamin B12 levels in Omani goats and suggests that younger animals, with lower levels of serum vitamin B12, might be more susceptible to vitamin B12 deficiencies than older animals.

Observations on haemoglobin types in three breeds of Omani goats

Haemoglobin (Hb) types were studied in three breeds of Omani goats, Batinah (n = 22), Jebel Akhdar (n = 27) and Dhofari (n = 85). Type A was the only adult Hb observed in adult Batinah and Jebel Akhdar goats. In contrast, only 34% of the Dhofari goats were homozygous for Hb A, while 66% were heterozygous for Hb A and Hb B. Dhofari goats with type AB could further be differentiated into those with approximately 67% type A and 33% type B and those with approximately 33% type A and 67% type B. None of the goats was homozygous for type B. Seventeen kids observed from birth exhibited different levels of fetal Hb, dependent upon whether they developed the adult phenotype AA or AB. Kids that became homozygous for type A were born with approximately 90% Hb F and 10% Hb A. In contrast, goats that developed the heterozygous AB phenotype were born with only 30–60% Hb F, the remaining Hb being types A and B. These findings are not in accordance with previous reports that kids are born without any adult Hb. Hb F was no longer detectable in any of the three breeds of goats at 49 days of age. There was no evidence of Hb C, the pre-adult form of Hb.

The effects of breed, neonatal age and pregnancy on the plasma copper status of goats in Oman.

There is a history of copper deficiency in grazing Omani livestock and the copper status of three economically important goat breeds, Jabal Akhdar (JA), Batina (B) and Dhofari (D) were therefore compared in October/November (cool season) and June (dry season) in a penned flock given a plentiful dietary supply of copper. In the cool season, 62 lactating does (5 JA, 12 B and 33 D), their 0–5-day-old kids (17 JA, 19 B and 22 D) and 25 dry does (17 JA, 5 B and 3 D) were blood sampled. In the dry season, the does sampled were either barren (15 JA, 16 B and 13 D) or pregnant (9 JA, 13 B and 33 D). The samples were analysed for total copper (TCu) and trichloroacetic acid (TCA)-soluble copper (TCA-sol Cu). There were no effects of breed on TCu or TCA-sol Cu in the cool season, the overall means being 0.75 (SE 0.049) and 0.59 (SE 0.052) mg/L. The mean TCu was low in kids at birth (0.59 mg/L) but had increased to 0.86 mg/L by 4 days of age (p<0.001); breed differences were found (p<0.002), the pooled values for JA, B and D being 0.77, 0.59 and 0.68 (SE 0.033–0.044) mg/L, respectively. By the dry season, the mean TCu had risen in barren does to 0.96 (0.045) mg/L but not in pregnant does (0.76 (0.047) mg/L; p<0.002) and breed differences had emerged, the mean for D being 20% lower than those for JA and B (p<0.05). The highest TCu values were found in the 7-month-old kids in June (1.17 (0.039) mg/L) but the breeds did not then differ. Some effects on TCA solubility were found but were considered unreliable. Breed effects may have been diminished by the generous supply of copper and early stage of lactation studied.