Identifier

etd-11182010-135949

Degree

Master of Science (MS)

Department

Animal Science (Animal, Dairy, and Poultry Sciences)

Document Type

Thesis

Abstract

The role of glucocorticoids on intestinal closure in neonates has recently become an area of interest but a definitive mechanism remains to be identified. It is known that glucocorticoids enhance immunoglobulin absorption in dairy calves, but the role of maternal glucocorticoids at parturition is not clear. In the present experiment, we obtained plasma and milk samples from primiparous and multiparous Holstein cows (n=24) to measure cortisol at 72, 48 and 24 hours before and 3, 6, 12, 24 and 48 hours after spontaneous parturition. After parturition, calves (n=24) were immediately removed from their dams and a blood sample was taken from the calf before colostrum ingestion (3 hours postpartum). Calves were sampled at 6, 12, 24 and 48 hours postpartum to measure plasma cortisol concentration and determine the concentration of plasma immunoglobulin G (IgG). Milk cortisol concentration in cows was significantly lower compared with plasma (5.4 ng/ml vs. 10.2 ng/ml) (P<0.0001). Cortisol in plasma and milk at 24 hours prepartum was significantly lower compared with 3 hours postpartum (4.2 ng/ml vs. 11.2 ng/ml) (P<0.05). Calf plasma cortisol was significantly elevated at 3 hours postpartum (258.1 ng/ml) and declined thereafter to 60.6 ng/ml by 48 hours postpartum (P<0.0001). Calf IgG in plasma was significantly lower at 3 hours postpartum (134 mg/ml) compared with 12 and 24 hours postpartum (2,324 mg/ml and 3,015 mg/ml, respectively), indicating minimal concentrations of antibody in plasma before colostrum ingestion. Calves were divided into “low” (n=11) and “high” (n=9) cortisol groups based on mean plasma cortisol concentration in their dams. Although the difference in cortisol at 3, 6 and 12 hours postpartum between cows of low cortisol and high cortisol (20.5 ng/ml vs. 39.1 ng/ml, 1.6 ng/ml vs. 19.1 ng/ml and 2.9 ng/ml vs. 13.4 ng/ml, respectively) was significantly different (P<0.05), there was no significant difference between cortisol or IgG concentration in low cortisol compared with high cortisol calves. The present results indicate that maternal cortisol concentration at parturition does not influence calf cortisol concentration at birth or IgG concentration.

Date

2010

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Godke, Robert A.

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