Concentration and Motility standards for frozen goat semen for use in Artificial Insemination 

Danni Louie

XCell Genetics,October 2024

     Understanding the relationship between frozen semen concentration and post thaw motility is an important factor for successful artificial insemination (AI) conception rates. The definition of concentration for semen is the number of sperm cells in a 1 ml sample. Note that goat semen is traditionally stored in 0.5 ml straws.  Thus, the number of sperm cells in a straw of semen is normally half the reported concentration.  Motility is defined as the ability for sperm to move and swim. When determining if a straw of semen is of adequate quality for conceptions in AI, the total number of motile sperm needs to be known.

     There are a range of reported numbers of motile sperm cells required in a sample for successful AI conceptions. Merck Veterinary manual states that 180 motile sperm cells are recommended for transcervical AI and as low as 20 million motile sperm for laparoscopic AI.  With this standard, concentration of semen would need to be 720 m/ml with a 50% motility. This is on the extremely high side of what is traditionally seen in the goat industry. 

     J.M. Corteel has suggested that 120 million motile sperm are required for successful AI in goats.  With this suggestion a concentration of 480 m/ml with a 50% motility would be considered ideal. This again is significantly higher than what has traditionally been seen in the goat industry

     XCell Genetics has analyzed multiple semen samples from various processors associated with the dairy goat industry using iSperm mCASA.  The range of concentrations were from 120 m/ml up to 300 m/ml.  The most common concentrations fell between 200 m/ml and 260 m/ml with motilities of 50% or higher.  This would suggest that the goat industry has had great success with 50-65 million motile sperm in a sample.

     Cornell University has stated that Dr. Louis C. Nuti found that samples with 30 million motile sperm produce suitable fertilization when proper AI procedures are followed.  This would mean that concentrations of 120 m/ml with 50% post thaws would produce suitable AI results.

     This shows that a range from 30 million to 180 million motile sperm have all been reported as giving suitable conception rates in goat AI.  This is what is important to understand when determining if a semen sample is of sufficient quality to yield successful conception rates in AI.  Motility and concentration must both be considered to determine the number of motile sperm cells in a sample.  Just because a sample is high concentration does not automatically make it the higher quality sample. For example, a sample with a 300 m/ml concentration with a 35% motility yields 52.5 million motile sperm in the straw.  A sample with 160 m/ml and a motility of 75% yields 60 million motile sperm in the straw. Both examples fall in the acceptable reported range of motile sperm cells needed for successful AI. However, the lower concentration sample actuals yielded 7.5 million more motile sperm in the straw versus the higher concentration sample.

     Knowing the concentration and motility of your goat semen samples, coupled with good record keeping, can help you to determine what number of motile sperm cells in a straw gives you the best results in your goat AI. Recognizing that the published acceptable range in goats for successful AI varies from 30 million to 180 million motile sperm cells.

Table 1. Blissberry semen evaluation for 2023-2024 AI.

Blissberry Dairy Goats has had a 71.4% conception rate on transcervical AI in dairy goats over the 2023 and 2024 season.  Table 1, above, shows the concentration, motility, number of motile sperm cells and the pregnancy result listed for all AI work done in the 2023 and 2024 breeding season. Semen was processed by three different long time, reputable semen processors associated with dairy goats. The concentrations ranged from 56.06-174.12 m/ml. Motility ranged from 34-70% with the number of motile cells per straw ranging from 13.73-59.24 million motile cells.  The average number of motile cells of the straws that produced pregnancies is 33.82 million motile cells per straw. 

References:

Cortell, J.M. 1975. The use of progestogens to control the oestrous cycle for the dairy goat. Ann. Biol. Anim. Biochem. Biophys. 15: 353-363.

Jamie Lynn Stewart, DVM, MS, PhD, DACT. Breeding in goats
     Merck Veterinary Manual. Nov, 2023

Louis C. Nuti. Goat Semen Collection and Processing Collection Manual. Cornell University. Page 28.