Pig breeding: Artificial Insemination advice and efficient selection of sows and gilts
To maximize returns on investments in commercial sow herds, the goal is to reduce culling and mortality rates. The main challenge or reason for culling for both sows and gilts is reproductive failure. To improve a sow’s productive life, farmers or producers must first understand the different reasons that lead to culling, coupled with in-depth knowledge of the sow or gilt’s selection process and proper conducting of artificial insemination.
Culling reasons
The main culling reasons to know are as follows:
Poor farrowing performance
Poor farrowing performance can be observed with prolonged farrowing, difficulty in giving birth, and retained placenta or piglets. This is usually accompanied by small litter sizes at birth, stillbirths, or mummified fetuses. Another bad sign is too early farrowing, usually more than 14 days before the expected date. Some sows also fail to produce or produce little milk.
Reproductive failures and health disorders
Signs of reproductive failures are observed in failure to conceive, abortion, failure to have a heat cycle, and longer dry periods. Vaginal infections, usually associated with vaginal discharge and fever, respiratory problems (pneumonia and asthma), weight loss, and poor body condition, are common indications of health disorders, among other signs.
Physical defects
The common defects are Downer Sow syndrome, small or damaged teats, rectal prolapse, inflamed tails, tumor or abscess growths, umbilical hernia, damaged vulva, and thin and weak sows.
Leg/foot problems, old age, and mortality
Leg problems are usually observed as lameness and locomotion problems (weak legs, splayed legs, flat-footed). In old age, sows in parity with greater than 5 are common targets for culling. The unnegotiable reason for culling is sudden death, which is prevalent in excessively heat-stressed sows.
To increase the longevity and lifetime efficiency of sows, producers can pay more attention to the following:
· Effective selection of both sows and replacement gilts
· Proper heat detection techniques and re-servicing of sows
· Timely and accurate diagnosis of reproductive failures in sows
· Controlling ammonia levels through effective monitoring of floor cleanliness and wetness
· Reducing the risk of leg disorders through proper stocking rates
· Enhancing nutrition strategies and reduction of heat stress by applying advanced cooling systems
Selecting sows
The typical production characteristics to be considered in the selection of sows are the number of piglets born alive, the number of piglets weaned, interval: weaning to service, production index, mortality, and longevity. Using the production capacity of the sow requires waiting for at least till the production of 2 or preferably 3 liters is known. Judging the external parts of the sow complements the selection based on genetic traits.
Judging the udder
Some positive attributes of a well-developed udder that are important for raising piglets:
- Number of teats (12 is a good minimum)
- A higher number of pair teats that are evenly distributed
- Equal spacing between the teats
- Well-attached udder and well-developed teats
Long life
Long life is important for a sow, especially in situations when gilts are more expensive than the older sows which are culled; it is then economically attractive to cull as few sows as possible. Some of the indications of a long life are:
- A strong back (a bit arched)
- Strong legs and proper gait
- In general, an attractive impression of the whole body
Selecting gilts
The selection of young replacement stock starts already in the farrowing pen. Already at that stage, the number of potential functional teats can be counted, and runts can be excluded. It is wise to select animals from a litter that does not show any genetic defects. If defects are shown, do not use the litter, preferably the sow and the boar that produces this litter for breeding purposes. If you do, the chance of genetic defects in the offspring will be higher.
A later selection is made at about 2 – 3 months, after which about 50% more than the needed number of gilts are left to be reared. A more detailed selection will follow in about 5 – 7 months. After this selection, only about 10% to 20% of extra gilts are left. This percentage depends on the farm size; the larger the number of gilts needed, the fewer extra gilts need to remain, though always keep an extra 5%, as usually, 5% of the gilts are not fertile. The selection at about 6 months of age can be done with the help of a farm test program.
In a recent study, scientists found that age at first oestrus, body weight, and weight gain of the replacement gilts significantly influence their subsequent reproductive performance as sows. The gilts mated at age ≤224 days exhibited first oestrus earlier and had a more significant weight gain than those mated at age >224 days. The gilts with delayed age at puberty, low body weight, and low weight gain had poorer subsequent reproductive performance and were removed from the herd earlier than those attaining early puberty, high body weight, and high weight gain.
AI centers or on-the-farm AI?
In today’s pig farming, most farmers with sows are using artificial insemination (AI). With ‘on-the-farm AI,’ farmers can store doses of semen on the farm for a certain period, enabling them to inseminate sows at the most appropriate time. In this system, the breeding quality of the boars supplying the semen is controlled by the breeding AI centers. AI center only takes care of the delivery of semen and charges the farmer accordingly. For the rest, the farmers must comply with the regulations set out by the AI centers.
However, some farmers still depend on the complete services of the AI centers; the AI center delivers the semen doses and does the insemination for the farmers. The advantage of AI centers is that for an agreed price, the AI station guarantees that the quality of the semen is of a good standard and is correctly inseminated.
In some establishments, the AI centers operate as co-operatives; in this case, with conception rates up to 90 % from AI, far better-quality boars, and the increasing numbers of sows at the farm level, it has become economically more attractive to join a co-operation as a member than maintaining your own boars.
Oestrus detection and insemination
Following the weaning of piglets, sows are placed into the breeding area, where it is advised to expose them daily to boars to induce oestrus and ovulation. For sows in stalls, boar exposure is normally performed using fenceline exposure for 1 to 2 minutes in the alleyway ahead of the sows while a technician applies back pressure at the rear. For females housed in pens, sows may be relocated to a boar exposure area where fenceline exposure is applied, or a boar may be moved into the sow pen for physical exposure. Electronic oestrus detection has also been used in group-housed sows and can aid in identifying sows in oestrus using 24-hour records for visits to an adjacent boar.
Most sows express oestrus 4 to 6 days after weaning, and commercial farm records indicate 90% of sows express oestrus and are inseminated within 7 days of weaning. Semen deliveries should be timed to occur before the first day of breeding with semen stored at 17 °C. Oestrus detection and insemination can be done at the same time, or detection of oestrus first and insemination later the same day. It is advised to perform the insemination in the presence of a boar to aid in standing and to induce myometrial contractions that aid in insemination and sperm transport. AI requires one to prevent the entry of bacteria by following strict sanitary procedures that include cleaning the vulva to remove urine and faeces and the use of a new or clean AI catheter at every insemination.
Concluding remarks
To select the right number of replacement stocks, it is important to know the several reasons that are considered for culling. The selection of sows and gilts requires a combination of genetic trait evaluation and judging of the body parts related to high production or mothering ability. The detection of oestrus and knowledge of artificial insemination is economically important, considering the cost of semen.
