Processing Fresh Semen

After collection of semen, it is necessary to evaluate the ejaculate to determine how many doses can be made. First, the volume and sperm concentration need to be determined. The number of doses is influenced by the number of doses actually needed and the number of sperm cells contained in the ejaculate. Other factors to be considered include conception data on the boar and physical appearance (morphology) of the sperm cells. We recommend a minimum of 5 to 6 billion sperm per dose for best results with high quality collections. It is also recommended to have 80-100 ml total volume per insemination dose to obtain maximum conception rate and litter size.

Volume
One way to attain volume is to simply place the bag of semen into a graduated beaker and make as close an estimation as possible. An electronic balance may give more precise estimations of volume (1 gram equals 1 ml).

Concentration
There are several ways to determine the concentration. Visual appraisal is simple and inexpensive, but is also the most inaccurate. The following table can be used to determine dilution rate following visual appraisal for concentration.

USAGE GUIDELINES FOR SEMEN EXTENSION

This table is intended as a general guideline and must be adapted to suit your breeding program and needs. There are many variables including age of boar, frequency of collection, genetic fertility of the boar as well as disease and other fertility problems that affect the number and quality of sperm produced. With the visual method 10-15 doses can usually be safely made per collection if the boar produces a volume within the usual ranges for the creamy, milk or skim milk classifications (i.e. dilute the semen to a total volume of 800-1200 mls). If the boar is less than 1 0 months of age or collected more than once or twice a week, he may produce a lower volume than listed as the usual range. In this case the number of doses may need to be reduced to 6 to 10 (480-800 mls total extended volume).

The use of a hemacytometer may also be employed. The hemacytometer is a special slide with a grid engraved on it. It also requires a 400 power microscope and a unopette. A unopette enables you to get a precise mixture of semen and diluent that can be placed on the hemacytometer and hand counted. Four fields of five squares each are counted to obtain an average count of the diluted sample. A dilution formula can then be used to determine an accurate concentration per ml of the original semen collection.

The most precise way to measure concentration is through use of the spectrophotometer. A measured sample of semen is placed in 3 ml of saline solution (in a cuvette) and run through the spectrophotometer. Due to the fact that the spectrophotometer is specially calibrated, it is highly accurate, but also the most expensive of the three options.

Using the volume and concentration obtained by one of the previously mentioned methods, the following formula calculates total billion sperm in the ejaculate:

Volume (ml) x concentration per ml = Total Sperm

Total sperm is usually expressed in terms of billions or 10'. Collection will range anywhere from 10 to 200 billion sperm. Normal range for rested boars is 40-100 billion. Before adding extender, its temperature should be matched to the temperature of the semen (± 1'C). It is best to warm the extender to approximately 35'C before collecting the boar. After collection, raise or lower the temperature of the extender to match the semen. Do not adjust the semen temperature. Extender should be added in two parts, at intervals of 10 minutes, to avoid dilution shock.

Always check sperm motility and morphology on a pre-warmed slide after dilution to ensure that the sperm have not been damaged during extending. For semen stored 24 hours or longer, check motility before use by warming a small amount (1-2 ml) to 34'C (93'F) prior to evaluation. Be careful not to overheat the semen sample when a drop is placed on the pre-warmed slide. In addition to forward motility one should check for the presence of bent tails or other abnormalities in the appearance of the sperm. With motility of less than 80-85% or more than 5-10% abnormalities, conception rate will be lower unless sperm concentration is adjusted above the 5-6 billion recommended per dose.

After semen has been extended, checked for quality and poured into bottles, it is ready to use or store. If you wish to store the semen it should be slowly cooled to 18'C and stored at that temperature. Semen should be gently mixed twice daily to avoid precipitation. Depending on the quality of the particular boar's semen and the type of extender used, it should remain viable for 1 to 7 days. Using SGI modena, viability and conception rate usually remain stable for 5 to 9 days after collection.

The following table lists recommended equipment and supplies needed for extending and processing liquid semen. SG] personnel will be happy to work with you to determine your specific needs.

RECOMMENDED EQUIPMENT

1. Water Bath Heater/Circulator
2. Mechanical Balance (Scale)
3. Hemacytometer and Accessories
4. Unopettes (100 per bottle) to be used with #3
5. Liquid Semen Storage Unit
6. Collection Dummy - Portable or Non-portable
7. Light Microscope (400x)

OPTIONAL EQUIPMENT

1. Electronic Balance (O HAUS GT 4800) replaces #2 Mechanical Balance
2. Semen Incubator (Precision Model 81 5) replaces Liquid Semen Storage Unit
3. Spectrophotometer and Accessories (including: Pipette, Repipette Dilutor, Pipette Tips, Cuvettes, 1 Case Test Tubes and 1 Test Tube Rack)
4. Binocular Microscope w/Phase Contrast, Heated Stage & Slide Warmer

LAB SUPPLIES

1. Modena Semen Extender
        1 Liter Pkgs. (1 Pkg. makes 1 Liter)
        3 Liter Pkgs. (1 Pkg. makes 3 Liters)
        5 kg Bulk - Makes 103 Liters total
2. 100 ml Plastic Bottles w/Cap (500 per box)
3. Contrad Cleaning Solution
4. Styrofoam Collection Container
5. Plastic Collection Bags
6. Gauze Squares
7. Glass Thermometers
8. Metal Dial Thermometers
9. 1 Gallon Plastic Bottles
10. Powder Funnels
11. 1,000 ml Beakers
12. Microscope Slides (1/2 gross/box)
13. Cover glass for slides (1 oz/box)
14. 600 ml Beakers
15. Disposable Collection Gloves (1 00/box)

Contact SGI for our detailed catalog and prices
on Al Equipment and Supplies.