Brucellosis and chlamydiosis seroprevalence in goats at livestock-wildlife interface areas of Zimbabwe.

In Zimbabwe, there have been no chlamydiosis and limited brucellosis studies in goats. This study was conducted to determine the seroprevalence and risk factors of the two diseases in goats at three different livestock-wildlife interface areas: porous, non-porous and non-interface in the south-eastern lowveld of Zimbabwe. Collected sera (n = 563) were tested for Brucella antibodies using the Rose Bengal plate test (RBPT) and the complement fixation test (CFT); and for Chlamydia abortus antibodies using the CFT. All tested goats were negative for Brucella antibodies. Overall, chlamydial seroprevalence was 22%. The porous [c2 = 9.6, odds ratio (OR) = 2.6, p = 0.002] and non-porous (c2 = 37.5, OR = 5.8, p < 0.00001) interfaces were approximately three and six times more likely to be chlamydial seropositive than the non-interface area, respectively. Chlamydial seroprevalence was not associated with sex (c2 = 0.5, OR = 1.2, p = 0.5), abortion history in female goats (c2 = 0.7, OR = 1.3, p = 0.4), keeping goats with cattle (c2 = 0.2, OR = 1.5, p = 0.7) or flock size (c2 = 0.03, OR = 1.4, p = 0.9). Our study provides the first serological evidence of chlamydiosis in goats in Zimbabwe and the results suggest that proximity to wildlife is associated with increased chlamydial seropositivity. Further studies are required to determine the role of chlamydial infection on goat reproductive failure and that of wildlife on C. abortus transmission to domestic ruminants.

Activities of the enzymes of hepatic gluconeogenesis in periparturient dairy cows with induced fatty liver.

The objective was to measure the activities of all the enzymes essential for hepatic gluconeogenesis in dairy cows with induced fatty liver. We aimed to induce severe fatty liver in ten experimental cows by overfeeding them during the dry period while seven control cows were maintained on a restricted diet. To induce a marked negative energy balance, the experimental cows were deprived of feed for 8 h immediately after parturition. In addition, the experimental cows were given a restricted amount of diet during the first 5 d of lactation. Liver samples were collected 1 week before and 1, 2 and 4 weeks after parturition. Before parturition, liver triacylglycerol concentrations did not differ between the two groups. After parturition, the experimental cows developed marked fatty liver as indicated by a higher level of triacylglycerols in the liver compared with the control cows. Before parturition, all gluconeogenic enzymes in the liver were lower in experimental cows than in control cows. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase and propionyl-CoA carboxylase were significantly lower and fructose 1,6-bisphosphatase and glucose 6-phosphatase tended to be lower in the experimental cows. The activities of two crucial enzymes for gluconeogenesis in ruminants, i.e., phosphoenolpyruvate carboxykinase and propionyl-CoA carboxylase, remained low throughout the sampling period post partum. Activities of pyruvate carboxylase and glucose 6-phosphatase in the experimental cows post partum were upgraded to values similar to those of the control cows. The results showed that the capacity for hepatic gluconeogenesis before parturition was lower in cows with induced fatty liver than in control cows. After parturition, the low activities of crucial gluconeogenic enzymes indicated insufficient production of glucose. It is suggested that the low gluconeogenic capacity leads successively to low blood glucose concentrations, low insulin levels and high rates of mobilization of fatty acid, causing severe hepatic lipidosis.

The effect of postpartum rumen undegradable protein supplementation on hepatic gluconeogenic enzyme activities in dairy cows with fatty liver.

The effect of postpartum supplementation with rumen undegradable protein on the activities of gluconeogenic enzymes was studied in cows with induced fatty liver. Prepartum liver and blood samples were collected at about one week before the expected date of calving and postpartum samples were collected at 10 and 20 days (d) postpartum. At 10 d postpartum, concentrations of serum nonesterified fatty acids and hepatic triacylglycerol levels were higher than at one wk before parturition. The postpartum increases in nonesterified fatty acids and hepatic triacylglycerols were significantly higher in the cows that were fed extra protein than in the control cows. There were no differences between the groups with regard to postpartum changes in the concentrations of plasma glucose, liver glycogen, and serum insulin. The postpartum increase in the activity of fructose 1-6-bisphosphatase was higher in the test group than in the control group, but the increase in the activity of glucose-6-phosphatase was lower. There were no group differences in the postpartum activities of phosphoenolpyruvate carboxykinase, pyruvate carboxylase, and propionyl-CoA carboxylase. Our results suggest that intense lipolysis released more glycerol in the protein-supplemented cows, which stimulated the activity of fructose 1-6-bisphosphatase. However, postpartum rumen undegradable protein supplementation did not affect the activities of the other enzymes of gluconeogenesis, and fatty liver was even exacerbated.