The relationship between sperm quality in cool-shipped semen and embryo recovery rate in horses.

This research explores the connection between the quality of cool-shipped stallion semen and the embryo recovery rate in horses, finding that better quality semen leads to higher embryo recovery rates.

Research Overview

The study’s aim was to shed a light on the unclear relationship between the quality of cool-shipped stallion semen and fertility. To this end, the researchers examined cool-shipped semen from 459 ejaculates, provided by 130 stallions. The semen was then used for the insemination of 196 embryo donor mares, across 496 cycles in estrus.

Findings and Results

The results revealed that the Embryo Recovery Rate (ERR), which represents the percentage of successfully recovered embryos, increased alongside all sperm quality measures, including:

• Motility – the ability of the sperm to move efficiently
• Viability – the proportion of live, healthy sperms in a semen sample
• DNA quality – the integrity of the sperm’s genetic material
• Morphology – the size and shape of the sperm
• Concentration – the number of sperm cells per milliliter of semen
• Total number – the total count of sperm cells in the ejaculate

Threshold Values

The study also reported threshold values for each sperm quality measure. For example, the threshold for total sperm motility was found to be 65%. Threshold values serve as the boundary that separates two ERR groups. For instance, with the aforementioned sperm motility threshold, an average of roughly 50% ERR was observed below this threshold, whereas a higher ERR of around 65% occurred above this value.

This research thus provides crucial insight into the importance of semen quality in determining fertility in horses, and offers a guideline for identifying semen of sufficient quality for successful embryo recovery. Furthermore, the findings can be used by vets and breeders to predict fertility outcomes based on semen quality parameters measured after cool shipping.