It’s 2025 and the statement that “reproductive efficiency is one of the primary drivers in herd profitability” has never been more true. With high replacement costs, high-value beef cross calves, and with many herds suffering holes in their reproductive programs due to devastating effects of avian influenza, getting cows pregnant in a timely manner is paramount.

Recent research by Crowe et al. (2024) (Figure1) shows that 30% of failed pregnancies occur between Day 1 and Day 18 of embryo development. Whether you are breeding for beef or dairy, using timed-AI or embryo transfer, these numbers reveal the significant opportunities that exist to enhance early embryo development by focusing on what embryos need most in their early stages of growth.

To that end, here are the top 5 areas affecting embryo development (Figure 2) and some practical suggestions that can help you fine tune your program for greater reproductive efficiency.

1. Maternal Nutrition

• Energy Balance: Negative energy balance (NEB) in postpartum cows can impair reproductive performance, affecting oocyte quality and uterine environment.
• Protein: Excess or deficient protein levels can influence uterine health and embryo development.
• Fat: EPA/DHA omega-3 fatty acids have been shown to increase day-7 blastocyst growth rate (Oseikria et al., 2016), as well as significantly reduce pregnancy loss. Adequate EPA/DHA also improves uterine repair and remodeling, which leads to better fertility outcomes.
• Micronutrients: Vitamins (A, B, and E) and minerals (e.g., selenium, zinc) play a critical role in maintaining fertility and supporting embryo growth.

2. Hormonal Environment

• Progesterone Levels: Adequate progesterone is essential for creating a supportive uterine environment and promoting embryo survival.
• Luteal Function: Poor corpus luteum function can lead to insufficient progesterone, impairing early development.

3. Uterine Health

• Postpartum Uterine Infections: Conditions like endometritis and metritis can disrupt the uterine environment, making it hostile to embryos.
• Inflammation: Elevated uterine inflammation affects endometrial receptivity and embryo survival.

4. Oocyte Quality

• Suboptimal oocyte competence, influenced by metabolic and hormonal imbalances, reduces the likelihood of successful fertilization and early development.
• Excess body condition loss post-calving leads to higher NEFAs and excess inflammation that directly impact oocyte quality.

5. Low Stress Environment

• Stress due to handling, housing, or inconsistent management practices can lead to hormonal imbalances and compromised fertility.
• Heat stress negatively impacts ovarian function, oocyte quality, and early embryonic survival. Elevated body temperature can hinder the maternal recognition of pregnancy.

Which of these areas need more attention on your dairy?

• While maternal nutrition may be dialed in, perhaps it’s time to re-evaluate the rumen-protected form of these nutrients (B vitamins, chelated minerals, EPA/DHA omega-3s) for better absorption and reproductive impact.
• If avian influenza caused more cows to be delayed in getting pregnant, perhaps a review of grouping strategies is to better manage body condition for healthier transition cows that breed better in the next lactation.
• And with summer in our near future, are there added measures that can be taken to improve cooling and reduce stress through the hot summer months? Perhaps this is the year that additional cooling measures get installed for your dry cows that result in benefits for both the dam and her next generation.

Whether you’re focused on filling in a gap in your reproductive program, chasing after additional beef x dairy revenue, or creating more replacements to sell, understanding what embryos need is a great step toward improving early embryo development and reproductive outcomes for your herd.