Date of Award

Winter 2014

Project Type

Thesis

Program or Major

Animal Sciences

Degree Name

Master of Science

First Advisor

Thomas L Foxall

Second Advisor

Charles G Schwab

Third Advisor

Andre F Brito

Abstract

In cattle sub-acute inflammatory disorders are difficult to assess because visual symptoms of diseases are not easily detectable with large numbers of dairy cattle in loose housing. In addition, inflammation is not always followed by leukocytosis in cattle, which makes the use of common blood tests like total white blood cell counts less reliable as a diagnostic tool. More sensitive and objective methods are needed to evaluate health status. Research has been focused on the use of acute phase proteins (APPs) to diagnose acute and chronic illness in cattle, because acute phase proteins respond very quickly when an inflammation event occurs, and they can be easily detected in blood. The most studied APPs in cattle are Haptoglobin (Hp), Serum Amyloid A (SAA), and Fibrinogen (FB). No studies have been done comparing the physiologic response of pasture-fed and TMR-fed confinement cows during a pasture season using acute phase proteins as markers of inflammation and stress.

Nine Jersey dairy cows were selected from the herd at the University of New Hampshire Burley-Demeritt Organic Dairy Research Farm and nine Jersey cows were matched to these cows by age, parity and stage of lactation and housed at the University of New Hampshire Fairchild Dairy Teaching and Research Center. APPs and white blood cells (WBC) were measured in the blood of these cows at 5 time points from April through September, 2012. Levels of Hp, SAA, and Fb were determined using a commercial bovine ELISA test kit. Whole blood from EDTA tubes was stained with Wright's stain for differential white blood cell counts. All levels were compared with the calculated temperature humidity index and health records.

All APP levels at both farms were within normal ranges established for healthy cattle. However, Hp, SAA, and WBC indicated a low level inflammation response that in some instances differed significantly between the two farms. Hp, SAA, and WBC levels in the pastured herd increased significantly by sample period 3, and remained elevated through sample period 4 and 5. Hp, SAA, and WBC in the conventional herd did not increase significantly until the 4th sample period and remained elevated for the 5th sample period. The Fb levels at both farms did not follow the same pattern seen with Hp, SAA, and WBC. Health records confirmed that minor inflammatory events may have been responsible for the rise in Fb levels, Neutrophil/Lymphocyte ratios between the two farms showed an increased inflammation response in the pastured cows over the entire sample period as compared to the TMR fed cows. Neutrophil lymphocyte ratios for the pastured herd were never within the normal limit set at 0.5 for healthy cattle at any of the 5 sample time points, where the TMR herd had normal levels at 3 sample time points.

These results indicated that the conventional herd had lower inflammation levels than the pastured herd over the entire study period and that common environmental conditions such as temperature and humidity may elicit a low level immune response in both management systems that can be measured in the blood using APPs and WBC.

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