Serum progesterone concentrations in cows receiving embryo transfers

Area of Science:

• Veterinary Science
• Reproductive Biology
• Endocrinology

Background:

• Embryo transfer (ET) is a key reproductive technology in cattle.
• Progesterone plays a crucial role in establishing and maintaining pregnancy.
• Accurate assessment of progesterone levels can help predict pregnancy outcomes in ET programs.

Purpose of the Study:

• To investigate the relationship between systemic progesterone concentrations and pregnancy success in crossbred cattle undergoing embryo transfer.
• To determine if early progesterone measurements can predict pregnancy outcomes.
• To analyze progesterone profiles in pregnant versus non-pregnant recipient cattle.

Main Methods:

• Radioimmunoassay (RIA) was used to quantify serum progesterone concentrations.
• Blood samples were collected from 528 recipient cattle at embryo transfer (Days 3-7 post-oestrus) and again between Days 9-14.
• Pregnancy was confirmed by rectal palpation between 45-65 days post-oestrus; further blood samples were taken on Days 20-22 in a subset of animals.

Main Results:

• No significant difference in progesterone levels was observed between pregnant and non-pregnant recipients on Days 3-14 post-oestrus.
• Significantly higher progesterone concentrations were found in pregnant recipients compared to non-pregnant recipients on Days 20-22 post-oestrus (5.14 ng/ml vs 1.17 ng/ml, P < 0.001).
• While early progesterone levels (Days 3-7) showed some correlation with later levels (Days 10-12), they did not reliably predict pregnancy outcome.

Conclusions:

• Serum progesterone concentrations on Days 20-22 post-oestrus are a reliable indicator of pregnancy status in cattle following embryo transfer.
• Early progesterone measurements (Days 3-14) are less effective in predicting pregnancy outcome in this context.
• Understanding progesterone dynamics is vital for optimizing cattle embryo transfer programs and improving reproductive efficiency.