Swine Reproduction

Breeding herds Replacement gilts Replacement gilts Sows Sows Boars Boars

The boar’s function in reproduction: 1. Produce spermatozoa 2. Introduce sperm into the female reproductive tract at the proper time

Reproductive Organs of the Boar Testes Testes Epididymus Epididymus Vas deferens Vas deferens most fluid in ejaculate Vesicular glands Vesicular glands Bulbourethral gland gel portion of ejaculate Urethra Penis

Boar’s Reproductive Tract

Boars Boars influence conception rate and litter size, and contribute one-half of the genetic makeup of their daughters. Boars influence conception rate and litter size, and contribute one-half of the genetic makeup of their daughters. Boars lacking fertility or sex drive should be culled as soon as possible. Boars lacking fertility or sex drive should be culled as soon as possible. For optimal breeding performance, mature boars should not be used for natural service more than twice daily; young boars should be used less often (2-3/week) For optimal breeding performance, mature boars should not be used for natural service more than twice daily; young boars should be used less often (2-3/week) The breeding system used should produce the best results in reproductive performance for the particular physical facilities and management program. The breeding system used should produce the best results in reproductive performance for the particular physical facilities and management program.

Boars Boars should be provided the best environment possible to enhance their breeding performance. Boars should be provided the best environment possible to enhance their breeding performance. Thermal stress should be prevented. Thermal stress should be prevented. Boars should be exposed to females as much as possible to stimulate male mating behavior. (20:1) Boars should be exposed to females as much as possible to stimulate male mating behavior. (20:1) Slippery floors should be avoided in the breeding area. Slippery floors should be avoided in the breeding area. Breeding records should be maintained to determine the reproductive performance of boars. Breeding records should be maintained to determine the reproductive performance of boars.

An ejaculate consists of the following three phases: 1. The first, or pre-sperm phase, which lasts 1 to 5 minutes, consists of a watery fluid in which there are tapioca-like pellets but no sperm, and comprises 5 to 20% of the ejaculate. 2. The sperm containing phase, which lasts 2 to 5 minutes, consists of a whitish, uniform fluid which contains the sperm, and comprises 30 to 50% of the ejaculate. 3. The last phase, which lasts 3 to 8 minutes contains very few sperm, helps form a gelatinous plug in the cervix of the sow, and comprises 40 to 60% of the total volume. The spermatogenic cycle in the boar is 35 days, with 10 days for epididymal transport. Thus 45 days are required from the start of production to ejaculation of sperm

fertility as measured by farrowing rates and litter size, gradually decreases as the prevalence of proximal (near the head) droplets increase

Semen Evaluation: Motility Motility Concentration Concentration Volume Volume Target: Motility: Motility: 60% or better Concentration & Volume: Concentration & Volume: Determine number of inseminations (3-5 billion)

The Sow’s Function in Reproduction: 1. To produce ova 2. To nourish the developing ova 3. To produce piglets 4. To produce milk

Reproductive Organs of the Sow 1. Ovaries 2. Oviducts 3. Uterus 4. Cervix 5. Vagina 6. Vulva

Sow’s Reproductive Tract

Puberty and breeding maturity Puberty: 5-7 months (hybrids perform better) Puberty: 5-7 months (hybrids perform better) Breeding: approx. 7 months Breeding: approx. 7 months Polyoestrous (temperature stress!) Polyoestrous (temperature stress!) Length of oestrous cycle 21 days Length of oestrous cycle 21 days Duration of oestrus 2-3 days Duration of oestrus 2-3 days Ovulation during the last day of oestrus (back Ovulation during the last day of oestrus (back pressure test) PGF2A-sensitivity only after day 12 PGF2A-sensitivity only after day 12

Breeding facts Estrus1-5 days Heat Period18-22 days Gestation114 days Breeding age-gilts7-8 mos. -boars7-8 mos. Breeding weight-gilts220 lbs.

Temperature effects on female Heat important when affects body temperature - Sources, both body and environment Effect oocyte cause polyploidyPrior to breeding is greatest loss of fertility Cause early embryonic mortalityEspecially within the first 7 days past breeding Late pregnant sow: Heat stress last week of gestation will greatly increase number of stillborn piglets Intensity of estrus may be reduced One mechanism, stress causes high glucocorticoids which inhibit LH release. Direct effects of heat on gametes is greatest effect! Low temperatures - Reduce intensity of estrus

Species variation in estrous cycle characteristics

Gilt exposure to a mature boar

Aspects off the vulva,, sexual behavior and fertility

Physical signs to consider for mating Too early Vulva heavily red and swollen Vulva heavily red and swollen Hardly any mucus on vaginal mucosa Hardly any mucus on vaginal mucosa Negative back pressure test, only standing reflex in presence of a boar Negative back pressure test, only standing reflex in presence of a boar In time Vulva moderately red and swollen Vulva moderately red and swollen Vaginal mucosa with mucus Vaginal mucosa with mucus Positive back pressure test Positive back pressure test Too late No redness or swelling of vulva No redness or swelling of vulva Sticky vaginal mucosa Sticky vaginal mucosa Negative back pressure test, only standing reflex in presence of a boar Negative back pressure test, only standing reflex in presence of a boar 2nd mating or AI ‘s are necessary in animals with positive back pressure test 24 h after mating

Gilt standing for "back pressure" test

Gilt "in heat", immobile Gilt with swollen vulva, secondary sign of estrus Gilt with swollen vulva, secondary sign of estrus Gilt with swollen vulva, secondary sign of estrus

Breeding The hypothalamus located at the base of the brain secretes gonadotropin releasing hormone (GnRH) >>>>> regulates the anterior pituitary gland >>>>> FSH (Follicle Stimulating Hormone) & LH (Luteinizing Hormone) into the blood which stimulates >>>>>>> ovarian hormones: estrogen and progesterone >>>>> which in turn regulate the reproductive process. The hypothalamus located at the base of the brain secretes gonadotropin releasing hormone (GnRH) >>>>> regulates the anterior pituitary gland >>>>> FSH (Follicle Stimulating Hormone) & LH (Luteinizing Hormone) into the blood which stimulates >>>>>>> ovarian hormones: estrogen and progesterone >>>>> which in turn regulate the reproductive process.pituitary glandpituitary gland Oxytocin is released from the posterior pituitary gland. Oxytocin is released from the posterior pituitary gland.

A.I.

References Sow gestation period??? Sow gestation period??? s/pigs.htm s/pigs.htm s/pigs.htm s/pigs.htm /publications/factsheets/812s.htm /publications/factsheets/812s.htm /publications/factsheets/812s.htm /publications/factsheets/812s.htm repro/physiol/reppaper.htm repro/physiol/reppaper.htm