Effects of long-term, near-term, and real-time energy balance, and blood progesterone concentrations, on the pregnancy rate of contemporary dairy cows

• Published in: Animal reproduction science 2018-02, Vol.189, p.136-145
• Main Authors: Gomez, N.A., Conley, A.J., Robinson, P.H.
• Format: Article
• Language: English
• Subjects: Adipose Tissue - metabolism; Animal Feed - analysis; Animal Nutritional Physiological Phenomena; Animals; Body Composition; Body condition score; Breeding; Cattle - physiology; Diet - veterinary; Energy balance; Energy Metabolism - physiology; Female; Insemination, Artificial - veterinary; Milk - chemistry; Pregnancy; Pregnancy Rate; Progesterone; Progesterone - blood; Reproduction
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2018.01.001

This study aimed to contribute to understanding the interface between reproductive and nutritional energetic physiology in contemporary dairy cattle. Multiparous Holstein cows (n = 32) between 70 and 180 days in milk were used in a study starting 10 d prior to the artificial insemination (AI) date and were estrous synchronized using a hormonal regimen. Fourteen cows were determined pregnant on day 39 post-AI. Coccygeal blood samples of all cows were collected on d −10 and −3 prior to AI to determine estrous cyclicity, as well as at AI and at 6, 13 and 20 d post-AI. Milk progesterone was measured 20 d post-AI, and body condition was scored (BCS; 1–5 scale) on days −10, 0, 13 and 27 relative to AI. Blood non-esterified fatty acid concentrations, measured on the same days as BCS, and changes of BCS from d −10 to AI were not predictive of pregnancy outcome. The BCS of cows on the day of AI was greater (P = 0.02) for pregnant cows with an approximate minimum BCS for a high probability of conception being 2.50. Serum progesterone concentrations of pregnant cows were greater (P