Some years after his death, Dr Santiago Martin Rillo of Spain continues to be celebrated for his contributions to improving practices of artificial insemination in pigs. The 12th international symposium in his name on swine reproduction and AI was held recently in the Spanish city of Toledo, attended by more than 100 participants from Europe, Latin America and Asia. Its full programme can be found online at: www.eaap.org/docs/Rillo.pdf.
It included an illustration of available concepts in AI technology, particularly in the area of predicting with a high degree of accuracy just when sows and gilts are likely to start ovulating. Dr Rodolfo Encarnación from PWG Genetics in the Philippines pointed out that the sow's eggs after ovulation had a life-span of only 8-12 hours, compared with the 24 hours that sperm from boar semen stay alive inside the sow after insemination. The breeding process has to be managed carefully because the window of opportunity is so narrow, he commented.
He recommended that breeding managers should record the number of days the animal takes to return to oestrus after weaning, as a basis for scheduling insemination times correctly. Remember that there is a relationship between the sow's weaning-to-oestrus interval and the length of her next heat cycle, said Dr Encarnación. When sows start cycling again within the general average of 5 days after weaning, their oestrus can be expected to last 3-4 days. But taking more than 7 days to return signifies that her heat will be short perhaps as little as 2 days and certainly no more than 3 days.
"This is important in predicting ovulation," he commented. "You need to know the time of the onset of oestrus, especially for gilts, and the number of days to return to a normal cycle post-weaning for all sows from the first parity onwards. Stock attendants in a breeding herd can anticipate events, by expecting that a particular sow will take the same number of days to return as in her previous parity.
"But it is also important to determine the specific hour when the gilt or sow shows the mating stance or standing heat reflex. From this, we can establish the best insemination timing schedule, whether you prefer to do only a single insemination or if you follow a multiple semen dosing concept of 2-3 inseminations for gilts and 3-4 inseminations for sows.
"So there is no substitute for perfecting your heat detection procedure. Of course, AI cannot succeed unless there is good hygiene and sanitation in preparing the semen doses, a correct evaluation of the semen and an optimum timing and number of inseminations. But I personally believe, based on almost 20 years of experience in doing work in pig AI, that 90% or more of the success depends on doing heat detection correctly."
Dr Encarnación advocated a routine of heat detection on 3 separate occasions each day. For example, the first could be in the morning between 06:00-07:00, the second around 13:00 and the third an evening check at 16:00-17:00. Place a teaser boar in front of the sows that are waiting to be re-mated, he advised, while checking for oestrus by conducting the back-pressure test on each female. For those on heat, a schedule of inseminations on the principle of multiple doses per sow should maximise her potential for conception and the litter size she yields at the next farrowing. Equally important is to be patient while inseminating sows. Do not rush the insemination process it may take between 5-15 minutes to complete.
Gilts deserve special attention, of course. Monitor signs of heat in these also 3 times daily, he insisted, and start doing that when they are just 6 months old. During the heat checks, introduce boar exposure for about 15 minutes daily also from the age of 6 months. At these times, observe any sign of loss of appetite or off-feed behaviour. Examine the vulva closely for changes in size or colour. Watch out for evidence of a discharge of mucus or a reddening of the opening to the vaginal canal.
For Dr Gustavo Pizzaro from Chile at the symposium, the secret of success in following a teaser boar programme for stimulating sows ahead of AI is the so-called 'Magic-42' concept. This thinks in terms of 3 cycles up to the first mating of gilts, he explained. Cycle 1 is to puberty, Cycle 2 to the animal's second oestrus after 21 days and Cycle 3 to the third heat at 42 days.
So the target is to mate gilts for the first time at the 42-days mark. Making it work well in practice requires a pen for the stimulation of oestrus and in this pen is a vasectomised boar.
A lesson from Brazil reported by Dr Maria Nazaré Torres was that a target of 30 pigs weaned per sow/year could be achieved, but only if highly competent and specialised personnel were taking care of the insemination process. AI is used more often than natural mating to breed sows in Brazil today, she commented. It accounts for about 60% of all breeding actions nationwide. There may be problems at times, such as an increase in the number of dead-born piglets, especially in the first litter. But the intensity of management is rather high, with an estimated average of 86 sows per person.
Brazilian herds described by Dr Nazaré are achieving a fertility rate of 94%. They tend to allocate plenty of space in the Eros Center. Sows can have about 2.5m2 of floor area per pig and gilts approximately 1.5m2. Litter sizes have been averaging 13.6 total piglets born, with 12.7 born alive. The herds have also limited pre-weaning losses so they wean 12 piglets per litter. PIGI