boar semen collection and evaluation

importance of boar semen collection

- central to swine artificial insemination program

- reduces risk of disease transmission compared to natural mating

- allow use of superior sires across multiple sows

- enhances efficiency and genetic progress in swine production

methods of boar semen collection

gloved hand technique, artificial vagina technique, electroejaculation

gloved hand technique

- most common technique

- mimics sows cervix using a warm, moistened glove

- required training of boar to mount dummy or sow in estrus

- collects semen in phases (pre-sperm, sperm-rich, post sperm)

artificial vagina

- less common for boars due to anatomical challenges

- requires precise temperature and pressure control

electroejaculation

- rarely used in swine (mostly for clinical/research)

- electrical stimulation induces ejaculation under anesthesia

semen collection steps

gloved hand method

- prepare dummy sow or estrus sow

- wash boars prepuce with warm water

- wear disposable glove, remove thumb for grip

- grasp boar penis and apply firm pressure

- collect ejaculate into pre-warmed collection vessel with filter

normal semen color

milky to creamy white (indicates healthy, concentrated sperm-rich fraction)

abnormal semen color

-clear/watery: low sperm concentration

-yellowish: possible urine contamination

-brownish/red: blood concentration (trauma or infection)

-greenish: infection or pus contamination

7.2-7.8

normal semen pH

slightly alkaline

______ = optimal for sperm survival

acidic

< 7.0

reduces motility, may indicate infection

highly alkaline

>8.0

may signal contamination or poor sample quality

volume (mL)

concentration (sperm cells/mL) measured via spectrophotometer or hemocytometer

motility (%)

proportion of the mobile sperm (light microscopy CASA systems)

morphology (%)

normal vs abnormal sperm cells

viability (%)

live vs dead sperm (stains: eosin-nigrosin)

factors affecting semen quality

- boar age and health

- collection frequency

- nutrition (adequate energy, protein, vitamins, and minerals)

- environment (temperature, stress, housing)

- handling and storage conditions

semen storage

- dilution with extender (nutrients and antibiotics)

- stored at 15-18 degrees C (not refrigerated at 4 degrees C)

- can remain viable for 3-5 days depending on extender type

- must avoid contamination, sudden temperature changes, and light exposure

motility

the ability of sperm to move actively and efficiently

- key indicator of semen quality and fertility potential

- acceptable percentage in boars: more than or equal to 70-80%

progressive motility

forward, linear motion of sperm cells (most desired)

Non-progressive motility

sperm move but in circles or irregular patterns

immotile sperm

sperm do not move

factors affecting motility

- temperature shock (cold stress)

- contamination or poor handling

- boar health and nutrition

- semen storage time and diluent quality