Observed and expected combined effects of clinical mastitis and low body condition on pregnancy loss in dairy cows

• Published in: Theriogenology 2012-01, Vol.77 (1), p.115-121
• Main Authors: Hernandez, Jorge A., Risco, Carlos A., Lima, Fabio S., Santos, Jose E.P.
• Format: Article
• Language: English
• Subjects: Abortion, Veterinary - etiology; Animals; artificial insemination; body condition; Body condition score; Body Constitution; Cattle; Clinical mastitis; Cross-Sectional Studies; Dairy cows; Embryonic loss; Female; insemination; mastitis; Mastitis, Bovine - complications; Postpartum Period; Pregnancy; Pregnancy loss; Risk Factors; uterus
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2011.07.023

The objective was to compare the observed and expected combined effects of clinical mastitis before timed artificial insemination (TAI) and low body condition at 70 d postpartum (dpp) on pregnancy loss in dairy cows. Cows were examined for pregnancy by ultrasonographic examination 28–32 d after TAI; the presence of an embryo with a heartbeat was the criterion used to determine pregnancy. Cows diagnosed pregnant were re-examined by transrectal palpation of the uterus and its contents 28 d later to confirm pregnancy status and to identify pregnancy loss. Eighty-eight (17%) of 512 cows were diagnosed with pregnancy loss. Cows affected with clinical mastitis before insemination and a body condition score (BCS) ≤ 2.75 at 70 dpp were 2.03 times more likely to experience pregnancy loss, compared to cows without clinical mastitis and with a BCS > 2.75 (RR = 2.03; 95% CI = 1.15, 3.60; P = 0.01). This observed combined effect for pregnancy loss (RR = 2.03) was higher than the expected combined effect based on adding (RR = 1.39) or multiplying (RR = 1.42) absolute independent excesses due to clinical mastitis or low body condition.