Relationship of Body Condition Score at Calving with Reproductive Performance, some Blood Metabolites and some Pathological Conditions in Holstein Cows

The study was conducted at The Great Diwaniyah cows station, located at the southern entrance of Al-Dagarah district - Al-Diwaniyah Governorate, from 6/12/2021 to 25/2/2023, to examine the relationship between body condition score (BCS) and reproductive traits, blood biomarkers, and metabolic diseases in Iraqi Holstein-Friesian cows. The 50 cows in parity2 were divided by body condition at calving into three groups (BCS1 = 2.5-3 point (17 cows), BCS2 = 3-4 point (20 cows), and BCS3 = 4 -5 point (13 cows)) based on 1-5 point scal. They were milked twice a day, morning and evening, by an automatic milking machine. The study found a substantial decrease (P≤0.01) in days open for BCS1 (77.18 days) compared to BCS2 (84.05 days) and BCS3 (88.23 days). The BCS2 group had considerably fewer days available (P≤0.01). Compared to BCS3. The study found a significant decrease (P≤0.01) in inter-calving interval for BCS1 group (354.59 days) compared to BCS2 and BCS3 groups (360.95 and 365.69 days, respectively). BCS2 group showed considerably shorter duration (P≤0.01) compared to BCS3 group. The study found no significant influence on inseminations per pregnancy or pregnancy length in the three cow groups. The study found that the BCS2 group had significantly higher glucose concentration (62.19 mg/100 ml) post-calving compared to BCS3 group (57.86 mg/100 ml), but BCS1 group did not differ significantly (59.30 mg/100 ml). The study found a substantial rise (P≤0.01) in BHB concentration (0.922 mmol/L) in the BCS3 group compared to BCS2 and BCS1 (0.743 and 0.674 mmol/L, respectively). BCS3 group showed a substantial increase (P≤0.01) in NEFA concentration (0.590 mmol/L) compared to BCS2 and BCS1 groups (0.476 and 0.461 mmol/L, respectively). During peak production, BCS2 group had a significant increase (P≤0.05) in glucose concentration (64.04 mg/100 ml) compared to BCS3 group (58.97 mg/100 ml), while BCS1 group did not differ significantly (60.97 mg/100 ml). BCS3 group showed a substantial increase (P≤0.01) in BHB concentration (0.434 mmol/L) compared to BCS2 and BCS1 groups (0.297 and 0.318 mmol/L, respectively). The study found a substantial increase (P≤0.01) in NEFA concentration in the BCS3 group (0.290 mmol/L) compared to BCS2 and BCS1 (0.205 and 0.215 mmol/L, respectively). The study found a significant (P≤0.05) increase in ketosis in Holstein cows with BCS2 and BCS3 groups, with rates of 1 (5.0%) and 2 (15.38%), respectively, compared to the BCS1 group with no injury. No significant changes were seen in placental retention, metritis, mastitis, and neonatal mortality between cows. According to the study, bodily condition during calving is linked to reproductive features, blood metabolites, and disease infection in cows.