Evaluating Automated Body Condition Scoring as a Predictor of Health and Reproductive Success in Dairy Cows

Objectives: The study aims to investigate the associations between automatically recorded Body Condition Score (BCS) and key metrics related to production, health, and reproduction, including milk yield, BHB levels, LDH, and progesterone. Methods: The research was conducted on a dairy farm in Lithuania, where cows were housed in a loose environment and fed a total mixed ration (TMR) tailored to their physiological needs. The diet consisted of corn silage, grass silage, grass hay, grain concentrate, and a mineral mixture, specifically formulated for a 550 kg Holstein cow producing 35 kg of milk daily. The study involved 597 cows, categorized into primiparous and multiparous groups. Key metrics such as β­ hydroxybutyrate (BHB), lactate dehydrogenase (LDH), progesterone (mP4), and milk yield (MY) were collected using the Herd Navigator system during milking, while health status was assessed by categorizing cows into four groups: healthy, subclinical ketosis, subclinical mastitis, and metritis. Results: The results indicated clear relationships between BCS, milk biomarkers, and productivity. A substantial 67.3 % of cows produced less than 31 kg of milk daily, with 80.7 % showing BHB levels below 0.06 mmol/L. LDH activity was below 27 µmol/min in 69.5 % of the cows, while milk progesterone levels were under 15.5 ng/mL in 28.8 % of cows. BCS was categorized as follows: 2.5–3.0 (21.4 %), >3.0–3.5 (50.8 %), and >3.5–4.0 (27.8 %).Pregnant cows had higher BCS (+0.29) and mP4 levels compared to non­ pregnant cows, who had lower milk yields (–5.26 kg/day). Cows with a BCS greater than 3.5–4.0 required 42.41 % more inseminations compared to those with a BCS of 2.5–3. 0. The group with the lowest BCS produced 29.55 % more milk than the group with the highest BCS, while mastitis was linked to a 4.96 % increase in BCS when compared to healthy cows. Conclusions: We discovered that a higher BCS is linked to increased pregnancy success, as pregnant cows demonstrated a BCS increase of 0.29 points, with mP4 levels being 10.93 ng/ mL higher than those in non­ pregnant cows during insemination. Cows with a BCS higher than 3.5–4.0 required 42.41 % more inseminations compared to those with a BCS of 2.5–3. 0. Furthermore, cows with subclinical mastitis exhibited a BCS that was 4.96 % higher than that of healthy cows. Significant differences in BCS (9.04 %) were also noted between the mastitis and metritis groups.