Association between oxidative stress and mastitis of dairy cows in period of early lactation

Nakov, Dimitar (2015) Association between oxidative stress and mastitis of dairy cows in period of early lactation. Doctoral thesis, University „St. Cyril and Methodius“ – Skopje, Faculty of Agriculture, Science and Food.

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Abstract

During the transition period important metabolic changes occur in dairy cows, which can also experience oxidative stress. The two years prospective study was carried out to assess the changes occurring in the activity of antioxidant enzymes superoxid dismutase (SOD) and glutathion peroxidase (GPX) between healthy CMT(-) cows and CMT(+) cows (on base of negative or positive reaction to California mastitis test). CMT(+) cows were subdivided in two groups: cows suffering from abnormal secretion of mammary gland (AS) and cows with intramammary infection (IMI). For this aim, there was observed totally 211 dairy cows, classified according sesons in years of calving and health status of mammary gland. Determination of the enzyme activity was performed on blood serum and milk whey with repeated measurements of activity made in three physiological periods: dry period 21 days before calving, period from beginning of lactation until 21st day in lactation, and period from 22nd to 42nd day in lactation. Аlso, there was followed monthly test day
milk yield of observed cows at the 1th, the 2nd and the 3rd monthly test day. The total prevalence of mammary health disorders (CMT(+) cows) was 43,13%. The prevalence of AS and IMI was 23,70% and 19,43%, respectively. The prevalence of
IMI from CMT(+) cows was 45,05%. Based on California mastitis test (CMT), there was found totally 162 positive quarters of mammary gland. The sensitivity of CMT to
intramammary infection was 43,82%.
The activity of SOD and GPx in blood and milk serum statisticlly significant (p<0.001) differed between season years of calving. Health disorders of mammary gland showed statisticlly significant influence (p<0.001) on GPx activity in blood serum and GPx activity in milk serum (p<0.05), but there wasn’t statisticlly significant influence on SOD
activity in blood and milk serum. Physiological stages in transition period when blood and milk samples was taken, showed statistical significant influence (p<0.001) on SOD and GPx activity in blood serum, but didn’t show statistical significant influence on SOD and GPx activity in milk serum. The milk yield in test days had statistical significant influence on GPx activity in milk serum. The GPx activity in blood and milk serum can be used as predictive biomarker for determination of mammary gland health status in early lactation.
Key words: dairy cows, mastitis, oxidative stress, superoxid dismutase, glutathion peroxidase

Item Type:	Thesis (Doctoral)
Subjects:	Agricultural Sciences > Veterinary science
Divisions:	Faculty of Agriculture
Depositing User:	Dimitar Nakov
Date Deposited:	24 Aug 2022 09:19
Last Modified:	24 Aug 2022 09:19
URI:	https://eprints.ugd.edu.mk/id/eprint/30127

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