Cost benefit analysis of lactation therapy with somatic cell counts as indications for treatment.

Lactating dairy cows (487) from five commercial herds were in a study of benefits from lactation therapy of sub-clinical mastitis. Bacterial isolations and composite milk samples for somatic cell counts were taken from each cow each month for 15 mo. Cows (254) in the experimental group were infused with cephapirin in all quarters for two consecutive milkings if somatic cell counts rose above 400,000 cells/ml; 103 cows were so treated. Stepwise regression showed that lactation number, somatic cell counts, days in milk, and percent quarters infected explained variation in milk production, but treatment group, herd, and season did not. Also, there were no significant differences between production of infected experimental and control cows with high somatic cell counts on test dates after treatment. With the experimental program, there was a net loss of +19.65/cow. Intramammary lactation therapy based on somatic cell counts less than 400,000 cells/ml is not recommended.