Effects of dietary antioxidants on glucose and insulin responses to glucose tolerance test in transition dairy cows.

Oxidative stress occurs during the transition period and causes insulin resistance, which may be reduced by the use of antioxidants in this period. Twenty-four multiparous Holstein dairy cows, at 8 wk before parturition, were divided into 4 equal groups, namely control (Ctrl), vitamin E (VE), selenium (Se), and vitamin E plus selenium (VE + Se) groups. On a daily basis, VE and Se cows received dietary 1.5 IU vitamin E/kg BW and 0.3 mg/kg DM selenium, respectively, from 8 wk before to 3 wk after parturition. Vitamin E plus selenium group received doses similar to VE and Se groups. Insulin sensitivity was evaluated through intravenous glucose tolerance test (ivGTT) at weekly intervals from 3 wk before to 3 wk after parturition. Serum concentrations of total antioxidant status (TAS), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), nonesterified fatty acid (NEFA), and beta-hydroxybutyric acid (BHBA) were assayed weekly before the commencement of ivGTT. Based on the results of ivGTT, the lowest and the highest degrees of insulin sensitivity were detected in Ctrl and VE + Se groups, respectively. The highest and the lowest concentrations of NEFA and BHBA were observed in Ctrl and VE + Se groups, respectively. Total antioxidant status, SOD, and GPx values were significantly lower in Ctrl cows and significantly higher in VE + Se-received cows compared with other groups. However, MDA values in Ctrl and VE + Se cows were significantly higher and lower than the other groups, respectively. Collectively, our results show that dietary administration of vitamin E and selenium ameliorates oxidative stress and lipid mobilization and increases insulin sensitivity in transition cows.

Detection of faecal Cryptosporidium parvum antigen in diarrheic Holstein dairy cows.

Over a one-year period, based on a random cluster sampling design, 661 faecal samples from natural cases of diarrheic calves were taken in Fars province of Iran. The samples were taken from the 267 diarrheic calves of high and 394 diarrheic calves of average producing Holstein dairy cows. Faecal samples were collected directly from the rectum. Herd selection was based on geographical location and density of cattle in the region. Samples were collected based on 5 percent of herd population in 4 geographical regions: North, West, East and South of Fars province. The herds were stratified into small, medium and large size. Laboratory investigation consisted of a direct identification test for antigen of Cryptosporidium parvum. All herds had HPDC and APDC Cryptosporidium-infected diarrheic calves in their population. Diarrheic Cryptosporidium infected HPDC calves in southern region of Fars province were at much lower risk (P<0.05) than APDC calves. The rate of Cryptosporidium infection in diarrheic APDC calves in southern region of Fars province was highest when compared to other geographical locations. When considering the effect of age, diarrheic Cryptosporidium affected APDC Holstein calves of younger dams (>2 to 3years) showed a higher rate of infection when compared to diarrheic HPDC Cryptosporidium infected ones. There were no differences among the occurrence of Cryptosporidium infection in diarrheic HPDC and APDC calves of different herd size groups.

Detection of faecal Cryptosporidium parvum antigen in diarrheic Holstein dairy cows

Over a one-year period, based on a random cluster sampling design, 661 faecal samples from natural cases of diarrheic calves were taken in Fars province of Iran. The samples were taken from the 267 diarrheic calves of high and 394 diarrheic calves of average producing Holstein dairy cows. Faecal samples were collected directly from the rectum. Herd selection was based on geographical location and density of cattle in the region. Samples were collected based on 5 percent of herd population in 4 geographical regions: North, West, East and South of Fars province. The herds were stratified into small, medium and large size. Laboratory investigation consisted of a direct identification test for antigen of Cryptosporidium parvum. All herds had HPDC and APDC Cryptosporidium-infected diarrheic calves in their population. Diarrheic Cryptosporidium infected HPDC calves in southern region of Fars province were at much lower risk (P2 to 3years) showed a higher rate of infection when compared to diarrheic HPDC Cryptosporidium infected ones. There were no differences among the occurrence of Cryptosporidium infection in diarrheic HPDC and APDC calves of different herd size groups.

Ischaemia/reperfusion injury in experimentally induced abomasal volvulus in sheep.

The purpose of the study was to evaluate ischaemia/reperfusion injury in simulated abomasal volvulus in sheep. Sixteen ewes were randomly allocated to three groups. The control group (n=4) served as sham-operated controls. The animals of the ischaemia group and reperfusion group (n=6, each) underwent a simulated 'abomasal volvulus'. The abomasum was exteriorized under general inhalation anesthesia and forced into a 180( composite function) anticlockwise rotation around its longitudinal axis, followed by another 270( composite function) anticlockwise rotation around its transectional axis. All ewes were monitored for 4 h. In the reperfusion group, volvulus was released after 3 h (i.e., 1 h of reperfusion). In the ischaemia group, the volvulus remained for 4 h (no reperfusion). Vital signs were monitored and some haematological and biochemical parameters were measured, without any significant differences. Full-section biopsy specimens were taken at the 3rd and 4th hours from the greater curvature of the abomasum. Histopathological lesions were scored according to the severity of mucosal oedema, submucosal oedema, haemorrhage submucosal and submuscularis layers, and polymorphonuclear infiltration on a scale of 0 to 4 (nil, mild, moderate, severe, and extreme). Another biopsy specimen was taken at the 4th hour for transmission electron microscopic examination. The scored lesions in light-microscopic examination were significantly different at the 3rd and 4th hours between the control and the experimental groups (p<0.05). There was no significant difference between the reperfusion and ischaemia groups (p>0.1). Within-group comparisons (3rd hour with 4th hour) revealed no significant differences. In transmission electron microscopic examination there were no remarkable changes in the control group, but in the ischaemia and reperfusion groups there were remarkable cellular (epithelial and goblet cells), mitochondrial and microvillous changes that strongly implied the occurrence of ischaemia (p<0.05). In transmission electron-microscopic examination of abomasal samples the lesions were more remarkable in reperfusion group than in the ischaemia group. It is concluded that ischaemia/reperfusion injury occurred in this model of simulated abomasal volvulus in sheep and that ischaemia/reperfusion injury should be considered as a potential determining factor in the outcome of cattle with abomasal volvulus.