PSXVII-17 Late-Breaking: Effect of cow’s social rank on calf’s passive immunity – a pilot study.

摘要

Social stress at the end of pregnancy may affect the transfer of passive immunity to calves through colostrum. To evaluate the effect of cow’s social rank on the antibodies transferred to the newborn calf, a pilot study was carried out at the Federal University of Santa Catarina’s (UFSC) Experimental Farm of Ressacada, Florianópolis, Brazil, under approval nº 5754200717 by the Animal Ethical Committee. Social hierarchy was evaluated three weeks before calving, for 7 days, through 1h observations of agonistic interactions during the corn silage supply. Three cows classified as low rank (L) and three as high rank (H) were used. Blood samples were collected from the calf at 12h, 48h and one week postpartum; colostrum at 12h and 48h postpartum. The development of calves (weight, height at withers and thoracic circumference) was monitored at blood collections and then monthly until 4 months of age. A Tukey and Kruskal-Wallis tests (p≤0.05) were used. Immunoglobulin G (IgG) content in calves’ serum was higher (p≤0.05) for H (3683mg/dL) than for L (2000mg/dL), only at one week of life. At 12h, blood’s total protein was higher for L calves (L=7.4, H=6.6 g/dL; p≤0.03) and hematocrit was lower (L=29.7, H=34.4 %; p≤0.05). There was no effect of social rank or time of collection for IgG content of cows’ colostrum (p