Swine Reproduction Papers
Table of Contents
Achieving success with AI is not difficult, but similar to natural service, certain factors, such as cases of female and male infertility, prevent the establishment of pregnancy and production of a litter. In pigs, AI use over the years has become the predominant form for breeding. The average pregnancy rates range between 75 to 90%, and litter sizes average between 10-11 pigs born. This technique and all its advantages are obviously here to stay.
Factors which increase the efficiency of the AI technique could result in higher pregnancy rates and larger litter sizes. Although many items may not be clearly established, the factors of greatest importance after timing and semen fertility, must include volume and sperm numbers inseminated. The volume and the number of sperm delivered into the uterus depend upon the ease of fluid flow into the female tract. Often, females are stimulated and actually suck the AI dose into the uterus. This can often occur very quickly and 80 cc will be inseminated within 30 seconds. This can happen with new collapsible bags and bottles. This vacuum is presumed to originate from oxytocin release resulting from neural stimulation of the sow. Often, no vacuum is evident and semen must be deposited with mild pressure. This does not result in reduced pregnancy rates but insemination takes longer. Mild pressure must often be used to begin semen flow. The insemination procedure should require about 2.5 to 3.5 minutes. Aids for stimulation include breeding harnesses and saddles, with or without semen holding devices. These provide some level of neural stimulation to aid in oxytocin release and for maintaining sow rigidity during AI.
Timing of artificial insemination is most important for maximizing pregnancy rates and litter sizes in swine. The most critical factor is ensuring that an insemination with fertile semen occurs at -18 to -12 hours before the moment of ovulation. The sperm inseminated require time in the female reproductive tract to reach the site of fertilization and time to gain the ability to bind and penetrate an egg (capacitation). Once the sperm reach the site of fertilization (within 30 minutes to 8 hours after deposition), they will attempt to fertilize an egg if one is present and they are capable. If the eggs are not present, then sperm will bind to the surface of the female oviduct and wait until ovulation occurs and hormones signal their release from the surface of the female tract. Once ovulated, the window for fertilizing the egg is approximately, 8-12 hours. After this time, even if fertilization of the egg does occur, abnormal embryos or embryos that survive fail to result in a fetus at farrowing.
AI Semen Components
Recently, the componets in extended semen have been evaluated for the effect on fertility. Since natural ejaculates contain numerous substances, including hormones, the effects of these factors has gained considerable attention.
Oxytocin addition to semen at 5 IU into the semen immediately before AI or injecting the sow prior to AI, has been shown to improve overall fertility. However, this method is controversial and the generalized recommendations for use should be made with caution, since the most profound effects occur in sub-fertile farms, groups of sows, seasonal infertility, and with sub-fertile boars. However, in many cases, farrowing rate and litter size are improved.
Seminal Plasma Other
|Standard AI Volume:||80-100 cc|
|Standard AI Times:||0 and 24 h|
|Breeding in Boar Presence:||Yes|
|Sperm Life in Extender:||3-5 day|
|Duration of AI:||0.5-4 minutes|
|AI Stimuli Techniques:||back or side pressure|
|Breeding Locations:||in crates and Pens|