Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Population Health & Reproduction
Non Technical Summary
Current practice in the California dairy industry is to inject an antibiotic into the teat when cows are dried off at the end of lactation. This practice is thought to aid the cow in treating bacterial infections and to prevent mastitis. But, treatment may reduce the efficacy of white blood cells by impairing mitochondrial function in peripheral blood mononuclear cells (PBMC) or somatic cells (SC) in the mammary gland. California Dairy Research Foundation (CDRF) has already funded the project exploring the impact of antibiotics on SC mitochondrial function in the mammary gland. This project addresses the extent to which mitochondrial function may be compromised in circulating PBMC by antibiotic use at the cessation of milking in the mammary gland. Approximately 20 cows per dairy (5 cows with low SCC (< 100,000) and no Ceftiofur, and 5 cows with low SCC and Ceftiofur; 5 cows with high SCC (> 200,000) and no Ceftiofur and 5 cows with high SCC and Ceftiofur) will be selected from 5 dairies to examine changes in circulating PBMC mitochondrial activity with antibiotic treatment. Dairies will treat 2 quarters per cow at dry off using Ceftiofur (Spectramast DC). Ceftiofur has been shown to change mitochondrial structure and reduce mitochondrial activity in white blood cells. Blood samples will be collected just prior to antibiotic treatment, 7 days later and finally 40 days in milk in the next lactation. Mitochondria will be isolated from PBMC to measure citrate synthase, and complexes I, IV and V activities. A reduced mitochondrial enzyme activity will indicate the effect of antibiotic treatment on mitochondrial PBMC activity. The results of this study will provide information supporting reduced use of antibiotics at cessation of milking and determine if there is a link between Ceftiofur use, mammary SC mitochondrial function, mastitis infection and transition disease.
Animal Health Component
20%
Research Effort Categories
Basic
60%
Applied
20%
Developmental
20%
Goals / Objectives
Objective 1: To quantify factors that impact supply and availability of nutrients utilized for efficient milk production while reducing environmental impact
Project Methods
The hypothesis is that Ceftiofur applied when cows are dried-off decreases PBMC mitochondrial function systemically as indicated by reduced mitochondrial citrate synthase, complex I, IV and V activities in PBMC and may increase transition issues. Cows (20 per dairy; 5 per treatment and SCC level) will be selected from 5 dairies to determine changes in mitochondrial activity of circulating PBMC due to antibiotic treatment with Ceftiofur at dry off. Cows will be enrolled at dry off according to SCC as determined by California Mastitis Test and milk samples will be taken to DHIA at each time point to quantify SCC in each quarter. Blood samples will be collected just prior to treatment at dry off, 7 days later and then 50 days after the next lactation begins. Mitochondria in PBMC will be isolated by membrane disruption and centrifugation. Mitochondrial enzyme activity (citrate synthase and complexes I, IV and V) will be assayed by colorimetric changes in a spectrophotometer and expressed relative to protein content (mOD/min/ug mitochondrial protein). Occurrence of transition diseases at 7 days in milk and from dairy herd management records. Enzyme activities in SC and circulating PBMC will be compared at each time point to determine the impact of Ceftiofur and SCC on mitochondrial function of immune cells. Data does not currently exist to estimate sample size. However, our past studies have shown that 5 cows are adequate to detect differences in PBMC mitochondrial enzyme activities. Differences in mitochondrial enzyme activities by treatment will be determined statistically using a mixed model with random effect of dairy. Occurrences of transition diseases will be compared across treatments with a similar mixed model.