Department of Management, Faculty of Economics, Trakia University, 6000 Stara Zagora, Bulgaria
(Manuscript received 22 August 2020; accepted for publication 16 October 2020)
Abstract. A study was conducted on the effect of clinical mastitis at Holstein-Friesian cows on the economic performance of dairy farms with different capacity. The study included three high-capacity farms in Bulgaria. The cows in all three farms are free-stall reared (freely in groups) and fed total mixed rations (TMR), in accordance with the animals’ milk yields, with milking performed at a milking parlor. In each farm, the cows were separated into two groups – ones affected by clinical mastitis and healthy cows throughout the entire 305-day lactation period. The results from the study indicated that dairy capacity was high for both groups, with 7567.5 kg for the healthy cows during the 305-day period, and 7429.7 kg for the afflicted ones. The fat content of milk from healthy cows was 3.5% with 3.24% milk protein, with the values being 3.43% and 3.18%, respectively, for the afflicted cows. The cows with mastitis in the three studied farms exhibited lowered economic results. Profit from the healthy cows was higher, by 8.4% in the third farm up to 21.2% for the second farm, compared to the results for the affected cows. Cost-efficiency is also higher for the healthy cows, and the production cost of 1 kg of milk was lower, which was due to the higher marketing of milk for processing and the better purchase price. Apart from the worse economic performance of the cows affected by clinical mastitis, their productive longevity and total lifetime utilization registered at the time of culling was reduced from 8.2% for the second up to 12.6% for the first farm.