R. A. M. Al Jassim

Seroepidemiology of Middle East respiratory syndrome (MERS) coronavirus in Saudi Arabia (1993) and Australia (2014) and characterisation of assay specificity

The pseudoparticle virus neutralisation test (ppNT) and a conventional microneutralisation (MN) assay are specific for detecting antibodies to Middle East respiratory syndrome coronavirus (MERS-CoV) when used in seroepidemiological studies in animals. Genetically diverse MERS-CoV appear antigenically similar in MN tests. We confirm that MERS-CoV was circulating in dromedaries in Saudi Arabia in 1993. Preliminary data suggest that feral Australian dromedaries may be free of MERS-CoV but larger confirmatory studies are needed.

Lactobacillus ruminis is a predominant lactic acid producing bacterium in the caecum and rectum of the pig.

Aims: To identify the predominant lactic acid producing bacteria in the small intestine, caecum and the rectum of the healthy pig.

Physiological responses of Australian Merino wethers exposed to high heat load

Twelve 9-mo-old Merino wethers (30.4 ± 3.2 kg of BW) were used in a crossover study to investigate the heat tolerance of Australian Merino sheep by testing their physiological responses to repeated heat loads that occurred during summer months. Wethers were randomly divided into 2 groups of 6 wethers each, housed individually in an environmental chamber, and subjected to 2 d of thermoneutral conditions (TNC) followed by either 7 d of TNC (maximum temperature of 24°C, minimum temperature of 16°C) or 7 d of hot conditions (maximum temperature of 38°C, minimum temperature of 28°C), and then 2 d of TNC. These treatments were applied in 2 replicates, with each replicate in a separate environmental chamber. Rectal temperature (RT) and respiration rate were measured daily at 0600, 0800, 1000, 1200, 1400, 1600, and 1800 h. Feed and water intakes were measured daily, and wethers were weighed on d 1 and 11. Blood samples were collected from each whether on d 2 and 6, and serum was assayed for concentrations of creatine, glucose, total protein, cholesterol, NEFA, calcium, sodium, and potassium. Exposure to a high ambient temperature resulted in an 0.8°C increase in RT (P < 0.001), an increase in respiration rate (P < 0.001) by 66 breaths/min, and a 2.7 L/d increase in water intake (P < 0.0001). Feed intake decreased by 22% (P < 0.0001), BW decreased by 5.2% (P < 0.03), and creatine concentration was reduced (P < 0.05). No differences (P > 0.05) between treatments were observed for any of the remaining serum variables. These results indicate that Australian Merino sheep were able to maintain RT within the normal range during exposure to a prolonged increase in heat and that they recovered quickly from the negative effect of heat stress within 2 d of conditions returning to TNC. It would appear that they have a high heat tolerance, and further studies are needed to examine the effects of a greater heat load to determine the temperature-humidity index thresholds for Australian Merino sheep.

Effect of various doses of injected selenium on performance and physiological responses of sheep to heat load

The aim of the study was to determine the effects of various doses of injected Se on the physiological responses of sheep to heat load. Fifteen 9-mo-old Australian Merino wethers (mean BW = 27.2 ± 2.1 kg) were randomly assigned to 1 of 3 treatments: 0 (control), 0.5, and 5 mg of Se, which was administered as a subcutaneous sodium selenate injection (5 mg/mL Se) on d 1, 8, and 15 of exposure to heat stress. The animals were housed individually in an environmental chamber and exposed to high temperature from 0700 to 1800 h (maximum = 38°C; minimum = 24°C) and to thermoneutral temperature from 1800 to 0700 h (maximum = 24°C; minimum = 20°C) for 21 d. Rectal temperature (RT) and respiration rate (RR) were measured daily at 0800, 1200, and 1600 h. Feed intake was measured daily, and sheep were weighed on d 1, 8, 15, and 21. Blood samples were collected on d 1 and 21. The 5 mg Se treatment decreased RT by 0.3°C (P = 0.02) and BW loss by 4.5% (P < 0.05) and increased eosinophil count (P < 0.05). There were no differences (P > 0.05) between treatments in RR and DMI, serum concentrations of glucose, total protein, cholesterol, and NEFA or in blood hematology variables. The findings of this study have important implications for the sheep industry. Further studies are warranted to elucidate the dynamics of Se on productivity and health during hot conditions.

In vitro effects of hydrochloric and lactic acids on bioelectric properties of equine gastric squamous mucosa

REASONS FOR PERFORMING STUDY Volatile fatty acids, byproducts of carbohydrate fermentation by resident bacteria, have been implicated in causing nonglandular (NG) gastric ulcers. Lactic acid (LA), also produced by stomach bacteria, may cause gastric ulcers when exposed to the equine NG mucosa. OBJECTIVES To investigate the in vitro effects of LA on equine NG mucosa bioelectric properties, sodium transport and tissue resistance. METHODS Gastric tissues obtained from 13 mature horses were studied in Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured, and electrical resistance (R) and conductance (G) calculated for tissues after addition of HCl and LA (5, 10, 20 and 40 mmol/l) in normal Ringers solution (NRS). RESULTS Mucosa exposed to HCl or LA (5, 10 and 20 mmol/l) in NRS (pH 1.5 and to a lesser extent pH 4.0) had a significant decrease in Isc and PD. Mucosa exposed to a high concentration of LA (40 mmol/l) in NRS (LRS) at pH 1.5 showed an increased G, but this increase was not significant. Values returned to baseline after solutions were returned to pH 7.0. Histological changes were consistent with HCl-induced (pH <4.0) acid damage. CONCLUSIONS HCl induced alteration in bioelectric properties of equine NG mucosa whereas addition of LRS did not, other than those changes seen with HCl alone.

Characterization of Streptococcus bovis from the rumen of the dromedary camel and Rusa deer

Aims:  Isolation and characterization of Streptococcus bovis from the dromedary camel and Rusa deer.

Evaluation of a PCR detection method for Escherichia coli O157:H7/H– bovine faecal samples

Aims:  Combinations of PCR primer sets were evaluated to establish a multiplex PCR method to specifically detect Escherichia coli O157:H7 genes in bovine faecal samples.

Effects of selenium and vitamin E on performance, physiological response, and selenium balance in heat-stressed sheep

Forty-two 7-mo-old Australian Merino wethers were used in a 50-d trial to investigate the effects of Se and vitamin E on the performance and physiological responses of heat-stressed sheep. Sheep were exposed to thermoneutral conditions (maximum = 24°C and minimum = 20°C) for 28 d followed by heat (maximum = 38°C and minimum = 28°C) for 22 d. Hot conditions were imposed between 0700 and 1800 h. Sheep were randomly allocated to diets containing 0.8 mg/kg Se (Sel-Plex), 150 mg/kg vitamin E, or 0.8 mg/kg Se and 150 mg/kg vitamin E for either the duration of the study (50 d) or from d 1 of the hot period until the end of the study. A control group that received no supplemental Se and vitamin E for the duration of the study was included. Feed intake was measured daily and sheep were weighed weekly. Blood samples were collected from all sheep before feeding on d 1, 21, and 49 for measurement of biochemical and enzymatic variables. The concentration of Se was determined in offered and refused feed, feces, urine, water, plasma, liver, and kidneys. Exposure to heat reduced ( < 0.05) DMI by 11.9%, ADG by 198 g, serum concentration of urea nitrogen and Se by 17.8%, and plasma total antioxidant status by 26.4%. During hot conditions, sheep receiving Se and vitamin E supplements for 50 d had reduced ( < 0.05) BW loss and elevated G:F compared to control sheep. Serum Se concentration and the plasma total antioxidant status were greatest in sheep receiving Se and vitamin E supplements for 50 d ( < 0.05). These results indicate that dietary supplementation with Se and vitamin E reduces the adverse effects of a high heat load. Additional studies are warranted to elucidate the mechanisms responsible for these effects.

The characterization of lactic acid producing bacteria from the rumen of dairy cattle grazing on improved pasture supplemented with wheat and barley grain.

Aims:  To identify and characterize the major lactic acid bacteria in the rumen of dairy cattle grazing improved pasture of rye grass and white clover and receiving a maize silage and grain supplement with and without virginiamycin.

Identification and characterisation of the predominant lactic acid-producing and lactic acid-utilising bacteria in the foregut of the feral camel (Camelus dromedarius) in Australia

The camel is emerging as a new and important animal in the Australian livestock industry. However, little is known regarding the microbial ecosystem of the gastrointestinal tract of this ruminant-like animal. This study was carried out to determine the diversity of lactic acid-producing and lactic acid-utilising bacteria in the foregut of the feral camel (Camelus dromedarius) in Australia. Putative lactic acid bacteria were isolated from the foregut contents of camels by culturing on De Man, Rogosa, Sharpe and lactic acid media. Identification of representative isolates was based on the analysis of 16S rRNA gene sequences. Fermentation end products of glucose (i.e. volatile fatty acids and lactate) were also measured in vitro. The key predominant bacteria identified in this study were closely related to Streptococcus bovis, Selenomonas ruminantium, Butyrivibrio fibrisolvens, Lachnospira pectinoschiza and Prevotella ruminicola. The main L-lactate producers were those isolates closely related to S. bovis, S. ruminantium and Lactococcus garvieae, while the efficient lactate utilisers were S. ruminantium-related isolates. D-lactate was produced by isolates closely related to either L. pectinoschiza or S. ruminantium. The predominant bacteria isolated and characterised in this study are identical and/or closely related to those typically found in true ruminants (e.g. S. ruminantium, B. fibrisolvens, S. bovis). In addition, some of the bacteria isolated represent novel species of Lachnospira and Clostridium in the context of lactic acid bacteria from a large herbivorous host. The results from this study have contributed to our understanding and provide opportunities to reduce foregut acidosis in the camel.