Monitoring udder health status using somatic cell counts in Iranian Holstein-Friesian dairy cows
Description
The present study was performed to provide update information about udder health as determined by SCC in Iranian Holstein-Friesian dairy cattle, and to compare results with herds under a mastitis control program. A total of 17,990 monthly test-day records from 1,663 Holstein dairy cattle in 10 commercial dairy herds (“regular herds”) and 2,389 test-day records from 386 Holstein dairy cattle from 2 herds that were assigned to the 10-point mastitis control program (“controlled mastitis herds”) were included in the analysis. Each test-day record comprised the date of recording, daily milk production (kg), fat and protein yields (%), days in milk at date of recording, parity and SCC. Median (Q1–Q3) SCC×103 for “regular” and “controlled mastitis herds” was 136 (52–391) and 64 (24–204) cells/mL, and the percentage of records containing SCC > 200,000 cells/mL (elevated SCC) was 40.3 and 25.5%, respectively (P < 0.001). Mixed effects logistic analysis revealed that milk records from primiparous cow, those at an early stage of lactation and records of > 40 kg of daily milk yield had lower odds of an elevated SCCs (P < 0.001). Also, the odds of an elevated SCC were lower in milk records taken in the summer and autumn than those taken in the winter (P < 0.05). The results demonstrated that udder health has been improved in Iranian Holstein dairy cattle over recent decade. There is some evidence that national mastitis control programs could support dairy producers in reaching a standard level. Host and environmental characteristics should be considered for the interpretation of SCC results.