Correlation between neonatal calf diarrhea and the level of maternally derived antibodies.

Passively acquired antibodies through colostrum will protect calves against etiological agents of neonatal calf diarrhea. Among them enteric diseases due to strains of Enterotoxigenic Escherichia coli (ETEC) are the most commonly occurring form of colibacillosis in newborn calves. Specific antibodies against whole ETEC cells and total immunoglobulin G in dam serum, colostrum and calf serum were determined. There were significant differences (P=0.0005) between antibody titers in normal and diarrheic groups, in which diarrheic group had a higher titer. Total IgG concentration in diarrheic calves (20.86 ± 0.49), their dams (23.48 ± 0.54) and colostrum (33.40 ± 0.50) was less than normal group (P=0.0005). There was a highly significant positive correlation between dam total IgG with calf total IgG (r=0.022; ratio=52.11). Colostral anti-E. coli antibody had a highly significant positive correlation with anti-E. coli in calf serum (r=0.345; ratio=0.62). Anti-E. coli antibody in calf serum had a highly significant negative correlati with total IgG of dam serum, colostrum and calf serum. While the level of anti-E. coli antibodies in diarrheic group was considerably higher than normal group, our findings reported here are in agreement that immunity to diarrhea also might be correlated with maternal cells or cellular components as well as cytokines which are transferred by colostrum to neonatal calves. Nevertheless, the level of maternally derived antibodies is a promising indicator for passive immunity and protection against diarrhea in neonatal calves.

Postpartum responses of dairy cows supplemented with n-3 fatty acids for different durations during the peripartal period.

The objective of this study was to determine the effect of different durations of n-3 supplementation during the peripartal period on production and reproduction performance of Holstein dairy cows. Thirty-two Holstein dry cows (16 multiparous and 16 primiparous) were blocked within parity for similar expected calving dates 8 wk before calving. Cows within blocks were assigned randomly to 1 of 4 treatments: (1) control without n-3 fatty acid (FA) supplementation during the dry period; (2) n-3 FA supplementation during the whole dry period (8 wk); and (3) n-3 FA supplementation during the early dry period (first 5 wk; far-off), or (4) n-3 FA supplementation during the late dry period (last 3 wk; close-up). All cows received the same diet without n-3 FA after calving for the first 6 wk of lactation. Ovaries of each cow were examined 10, 17, 24, and 34 d from calving (calving=d 0) by transrectal ultrasonography to determine follicular development. Blood samples were collected at 14-d intervals starting on the first day of the dry period (8 wk before expected calving) to determine plasma concentrations of glucose, ß-hydroxybutyrate, nonesterified fatty acids, urea N, aspartate aminotransferase, and insulin. Blood samples were also collected on d 1, 10, 17, 24, 31, and 38 postpartum for determination of progesterone concentration. Milk yield was recorded daily throughout the experiment and samples were taken twice weekly (Monday and Thursday mornings) for analysis of fat, protein, and lactose. Yields of milk and 4% fat-corrected milk and milk composition were similar among treatments except for fat proportion, which tended to be lower in cows that were fed n-3 FA throughout the dry period. We observed no differences among treatments for plasma concentrations of metabolites and hormones. The cows that were fed in the 3 n-3 FA treatments had larger ovulatory follicles compared with those fed the controlled diet. Treatments did not differ significantly in terms of the number of days open, day to first service, or number of services per pregnancy. In conclusion, n-3 FA supplementation throughout the dry period or in the early or late prepartal period had no carryover reproductive postpartum benefits and no effect on the production of Holstein dairy cows.

The effect of Protexin on prevention of ileocecal infection by Mycobacterium avium subspecies paratuberculosis in dairy calves.

The objective of this study was to evaluate the effect of Protexin (Probiotics International Ltd., South Petherton, UK) in the prevention of ileocecal infection by Mycobacterium avium ssp. paratuberculosis (MAP) in dairy calves in the field situation. Forty Holstein bull calves whose dams were paratuberculosis negative (confirmed by serum ELISA test and fecal nested PCR) were randomly selected in 2 groups. All calves were fed raw milk collected from the bulk tank in a paratuberculosis-infected dairy farm, which was confirmed by PCR. The treatment group (20 calves) was given 2 g of Protexin from birth until weaning (90 d). The control group (20 calves) did not consume Protexin. The calves were culled at 12 mo of age and the ileocecal lymph nodes were sampled. The lymph nodes were tested by nested PCR to evaluate MAP infection. In the treatment group, 2 out of 20 calf (10%) ileoceca were infected by MAP, whereas in the control group, 8 out of 20 calf (40%) ileoceca were infected by MAP. A significant difference existed between ileocecal infection by MAP in treatment and control groups. Thus, Protexin showed a significant effect in decreasing the ileocecal infection by MAP.

Phylogenetic analysis of the hemagglutinin genes of 12 H9N2 influenza viruses isolated from chickens in Iran from 2003 to 2005.

In the present study, the hemagglutinin genes from 12 influenza viruses of the H9N2 subtype were isolated from chicken flocks in different provinces of Iran from 2003 to 2005, amplified and sequenced. All of the 12 isolates showed similar sequences at the cleavage site, RSSF/GLF, bearing eight potential glycosylation sites and sharing the characteristic deduced amino acid residues alanine-190, glutamine-226, and glutamine-227 at the receptor-binding site. Ten out of these 12 isolates possessed leucine at position 226, which prevails in the sequences found in human H2 and H3 strains. Overall, the presence in these Iranian poultry H9N2 viruses of the sequence known to bind to human-type receptors and the presence of antibodies in the human population of Iran to H9N2 showed that it is possible for circulating H9N2 avian influenza viruses in Iran to infect humans. Hence, extensive surveillance of H9N2 in this country is highly recommended.