Med. Weter. 81
full text
| WOJCIECH BARAŃSKI, SŁAWOMIR ZDUŃCZYK, MARIANNA ZIELIŃSKA, JULIA KLAJNA |
| Changes in the incidence of anoestrus and its clinical forms in dairy cows in north-eastern Poland over the last two decades |
| The aim of the study was to evaluate changes in the incidence of anoestrous conditions in several dairy cow herds over the past 20 years in north-eastern Poland. In calving season 2003-2004, 1215 crossbred cows (Polish Black-and-White × Holstein-Friesian) from 8 herds were used. The average milk yield was about 5000 kg per year. In calving season 2023-2024, 942 Holstein-Friesian cows from 5 herds were used. The average milk yield was about 9000 kg milk per year. Anoestrous cows were examined twice by ultrasonography at a 7-10 day interval between days 50 and 60 after parturition. In 2003-2004, anoestrus was observed on average in 33.1% of cows. The main clinical form of anoestrus was silent heat (44.0%), followed by ovarian afunction (43.3%), ovarian cysts (9.2%), corpus luteum pseudograviditatis (2.1%) and persistent follicles (1.4%). In 2023-2024, anoestrus was observed in 43.5% of cows. Silent heat was diagnosed in 41.0%, persistent ovarian follicles in 34.9%, ovarian cysts in 18.0%, ovarian afunction in 4.9% and corpus luteum pseudograviditatis in 1.2% of anoestrous cows. There was a significantly higher incidence of anoestrus (p < 0.05) in calving season 2003-2004, compared to calving season 2023-2024. The difference between the two calving seasons in the proportion of ovarian afunction, persistent ovarian follicles and ovarian cysts in anoestrus cows was statistically significant (p < 0.05). The study shows that over the past two decades there has been an increase in the incidence of anoestrus in dairy cows and changes in the proportion of its clinical forms, in particular in ovarian afunction, persistence of ovarian follicles and ovarian cysts. |
| Key words: cows, anestrus, clinical forms, milk yield |