| Summary: | <p><span>Anestrous postpartum is a state of complete sexual inactivity without estrous manifestations and the return of ovarian activity in postpartum may be negatively affected by several factors, such as negative energy balance (NEB), loss of body condition score (BCS), season in which the calving occurs, nutritional deficiencies, dystocic calving, retained placenta, uterine infections and metabolic diseases. This study aimed to evaluate the effects of BCS and number of days in milk (DIM) on ovarian cyclicity of Holstein dairy cows. Ovarian conditions of 168 cows between 30 to 90 days in milk (DIM) were evaluated twice by ultrasonography with seven days of interval and cows were classified in four categories: ovaries with presence of small follicles (Category 1: up to 10 mm); ovaries with medium follicles (Category 2: 10 to 18 mm); ovaries with large follicles (Category 3: over 20 mm) and ovaries with presence of corpus luteum (CL) (Category 4). The cows classified in categories 1, 2 and 3 were considered in anestrous. Data were analyzed by logistic regression at Minitab (P<0.05). As a result 15 cows (8.93%) were in Category 1, 34 (20.24%) in Category 2, 4 (2.38%) in Category 3 and 115 (68.45%) in Category 4. There was no effect (P>0.05) of DIM in the percentage of cycling cows, however there was a tendency (P=0.074) that cows with greater BCS (≥ 2.75) had a higher cyclicity rate (74.44% vs. 61.54%) than cows with lower BCS. Days in milk effect was not detected in cyclicity rate in cows between 30 and 90 DIM, but there was a tendency of Holstein cows with greater body condition score to had higher cyclicity rate.</span></p>
|
|---|
