The metabolic response to norepinephrine in carbon tetrachloride poisoned sheep

The intraruminal administration of carbon tetrachloride to healthy sheep caused a sharp rise in the serum OCT levels. The plasma concentration of non-esterified fatty acids (NEFA) increased, while blood glucose remained unaffected. The glucose response to the intravenous injection of norepinephrine was greatly reduced after carbon tetrachloride administration, indicating a depletion of the liver glycogen. The NEFA response was not altered. As the increase in NEFA caused by carbon tetrachloride was only moderate, a block in lipoproteinsynthesis is discussed as the main factor in the development of the fatty liver.     

Bromosulphophthalein clearance rates in sheep with pyrrolizidine liver damage.

Sheep fed a ration containing 50% of dried Heliotropium europaeum showed a marked decline in bromosulphophthalein (BSP) fractional clearance rate during the first 3 months feeding. Thereafter, the response of individual animals varied widely on a time basis, although 3 groups could be identified. In the terminal stages, mean clearance rates were below 20% of initial values, with some sheep showing a decline in excess of 90%. Loss of liver functional capacity was generally much greater than indicated by the degree of damage revealed by histopathology. Thus, a suitably modified test could have considerable prognostic value in the field. In this investigation, all sheep with clearance rates below 0.15 died when exposed to a further period of H. europaeum feeding.     

An omaso-abomasal cannula used to assess efflux from the omasum of sheep

An omaso-abomasal cannulation technique was developed for sheep to assess efflux from the omasum. The procedure enabled the collection of the total omasal effluent and avoided transection of the innervation and circulation of this region of the gut. Eating was associated with an increase in flow of the fluid and dry matter fractions of digesta passing from the omasum but efflux was unaffected by rumination. There were few protozoa and flagellated organisms in the omasal effluent relative to the numbers in ruminal fluid. The preparation was used over 3 months of study.     

A comparison of vitamin B12 levels in the liver and serum of sheep receiving treatments used to correct cobalt deficiency

The efficacies of four methods, used for the prophylaxis of cobalt deficiency in sheep as measured by the elevation of liver and serum vitamin B₁₂ levels, were compared in marginally deficient sheep over 14 weeks. The methods used were weekly drenches of either cobalt sulphate or cobalt chelate (EDTA); three-weekly injections of hydroxocobalamin, and ruminal cobalt pellets.

On the basis of elevated liver and serum vitamin B₁₂ levels, chelated cobalt was shown to be available to rumen microflora for the synthesis of vitamin B12. However, at no stage were liver and serum vitamin B₁₂ levels of sheep receiving the chelate significantly different from those receiving the same amount of cobalt as the sulphate.

After five, three-weekly injections of hydroxocabalamin liver vitamin B₁₂ levels were significantly higher (p < 0.01) than for the other treatments, with the exception of cobalt sulphate.

Cobalt pellets led to an initial rapid and significant rise in serum vitamin B₁₂ when compared with the other treatments. However, at four weeks there was no significant difference between treatment groups for serum vitamin B₁₂. Fourteen weeks after the administration of cobalt pellets, serum and liver. vitamin B₁₂ levels in this group were not significantly different from those of untreated sheep. At this time, three out of 12 sheep had lost their pellets.     

A comparison of vitamin B12 levels in the liver and serum of sheep receiving treatments used to correct cobalt deficiency

The efficacies of four methods, used for the prophylaxis of cobalt deficiency in sheep as measured by the elevation of liver and serum vitamin B12 levels, were compared in marginally deficient sheep over 14 weeks. The methods used were weekly drenches of either cobalt sulphate or cobalt chelate (EDTA) three-weekly injections of hydroxocobalamin, and ruminal cobalt pellets. On the basis of elevated liver and serum vitamin B12 levels, chelated cobalt was shown to be available to rumen microflora for the synthesis of vitamin B12. However, at no stage were liver and serum vitamin B12 levels of sheep receiving the chelate significantly different from those receiving the same amount of cobalt as the sulphate. After five, three-weekly injections of hydroxocabalamin liver vitamin B12 levels were significantly higher (p<0.01) than for the other treatments, with the exception of cobalt sulphate. Cobalt pellets led to an initial rapid and significant rise in serum vitamin B12 when compared with the other treatments. However, at four weeks there was no significant difference between treatment groups for serum vitamin B12. Fourteen weeks after the administration of cobalt pellets, serum and liver.vitamin B12 levels in this group were not significantly different from those of untreated sheep. At this time, three out of 12 sheep had lost their pellets.     

A comparison of six methods used for detecting pregnancy in sheep

The speed and accuracy of 4 ultrasonic devices (Scanopreg, Pregmatic 3, Medata external probe and Medata rectal probe) were compared with udder scoring and harnessed vasectomised rams as methods of pregnancy diagnosis in 177 ewes, 59 of which were non-pregnant. When using the Scanopreg in ewes of greater than 50 days gestation, accuracy in pregnant ewes averaged 98% and in non-pregnant ewes 87%. The Pregmatic 3 was 97% accurate in pregnant ewes after 50 days gestation and was 96% accurate in non-pregnant ewes. Ewes were examined at between 85 and 185 per hour using these devices. The Medata external probe was 99% accurate in pregnant ewes of greater than 110 days gestation but less accurate in early gestation. This instrument averaged 89% accuracy in non-pregnant ewes and an examination rate of 29 to 35 ewes per hour was achieved. The Medata rectal probe averaged 85% accuracy in pregnant ewes after 70 days gestation. Accuracy averaged 94% in non-pregnant ewes. Ewes were examined at between 35 and 59 per hour using this device. After 130 days gestation 84% of ewes had firm, obviously enlarge udders and another 14% had slight to moderate udder development. After 130 days gestation thick, clear udder secretions were expressed from 18% of ewes and thick, milky udder secretions were expressed from 8%. Harnessed vasectomised rams raddled one of 118 pregnant ewes (an accuracy in pregnant sheep of 99%) and raddled 53% of non pregnant ewes. It was concluded that the ultrasonic pregnancy testing devices have a commercial role, especially as aids to decision making.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in the concentrations of bile acids in the plasma of sheep with liver damage

The concentration of total plasma bile acids was measured in normal sheep and in sheep in which liver damage was induced by chronic copper poisoning, ligated bile ducts or induced ketosis. All three treatments produced a rise in total bile acid concentration in plasma which was proportional to the degree of hepatic damage seen histologically and which tended to parallel changes in activity of iditol, and glutamate dehydrogenase and aspartate amino-transferase in plasma. Plasma bile acid concentration was a more sensitive method of detecting these types of liver damage than was the measurement of total plasma bilirubin concentration, and could be used to assess alterations in liver function in sheep.     

Serum gamma-glutamyltransferase as a measure of sporidesmin-induced liver damage in sheep

The relationship between serum concentrations of the enzyme gamma-glutamyltransferase (GGT) after experimental sporidesmin intoxication, and the severity of the liver damage seen on post-mortem examination of the liver, has been examined. Serum GGT activity in blood collected 2 to 3 weeks after ad-ministering the toxin is positively correlated to a subjective liver damage score and to losses in bodyweight associated with the intoxication. Determination of GGT activities provides a sensitive method for detecting and measuring liver damage in experimental sporidesmin poisoning. In the field, GGT determinations should prove useful in diagnosing liver damage associated with subclinical and clinical facial eczema giving additional information about the severity of the lesion.     

A comparison of the effects of carbon dioxide and medical air for abdominal insufflation on respiratory parameters in xylazine-sedated sheep undergoing laparoscopic artificial insemination

AIMS: To determine if abdominal insufflation with medical air will improve oxygenation and ventilation parameters when compared to insufflation with CO₂ in xylazine-sedated sheep undergoing laparoscopic artificial insemination (AI).

METHODS: Forty-seven sheep underwent oestrus synchronisation and were fasted for 24 hours prior to laparoscopic AI. Each animal was randomised to receive either CO₂ or medical air for abdominal insufflation. An auricular arterial catheter was placed and utilised for serial blood sampling. Respiratory rates (RR) and arterial blood samples were collected at baseline, after xylazine (0.1?mg/kg I/V) sedation, 2 minutes after Trendelenburg positioning, 5 minutes after abdominal insufflation, and 10 minutes after being returned to a standing position. Blood samples were collected in heparinised syringes, stored on ice, and analysed for arterial pH, partial pressure of arterial O₂ (PaO₂), and CO₂ (PaCO₂). The number of ewes conceiving to AI was also determined.

RESULTS: Repeated measures ANOVA demonstrated temporal effects on RR, PaO₂, PaCO₂ and arterial pH during the laparoscopic AI procedure (p<0.001), but no difference between insufflation groups (p>0.01). No sheep experienced hypercapnia (PaCO₂>50?mmHg) or acidaemia (pH<7.35). Hypoxaemia (PaO₂<70?mmHg) was diagnosed during the procedure in 14/22 (64%) ewes in the CO₂ group compared with 8/23 (35%) ewes in the medical air group (p=0.053). Overall, 15/20 (75%) ewes in the CO₂ group conceived to AI compared with 16/22 (72.7%) in the medical air group (p=0.867).

CONCLUSIONS AND CLINICAL RELEVANCE: There were no statistical or clinical differences in RR, PaO₂, PaCO₂, pH, or conception to AI when comparing the effects of CO₂ and medical air as abdominal insufflation gases. None of the sheep experienced hypercapnia or acidaemic, yet 42% (19/45) of sheep developed clinical hypoxaemia, with a higher percentage of ewes in the CO₂ group developing hypoxaemia than in the medical air group. Based on the overall analysis, medical air could be utilised as a comparable alternative for abdominal insufflation during laparoscopic AI procedures.     

Fibrinogen-degrading proteins from Haemonchus contortus used to vaccinate sheep.

Sixteen nonsibling sheep, approximately 12 months old, that were raised in a helminth-free environment, were used for 2 protection studies 6 months apart. Sheep were vaccinated weekly for 5 weeks by IM injection of fibrinogen-degrading proteins derived from the intestinal tract of adult Haemonchus contortus. Ten days after the last vaccination, sheep were given 2,500 infective H contortus larvae by intraruminal injection. Vaccinated sheep produced specific antibodies, and were protected from the worm challenge. Significant differences in mean fecal worm egg counts for 56 days after worm challenge, in mean numbers of H contortus worms, and female fecundity ratios at necropsy were detected in vaccinated sheep, compared with those in control sheep. These data suggest that the fibrinogen-degrading proteins have a protective role in vaccination of sheep against H contortus.