Timing And Quality - Keys To Breeding Performance On Sow Farms

High conception rates are vital to productivity on any sow farm, be it a farrow-to-wean, farrow-to-feeder pig, or farrow-to-finish unit. Indeed swine farm enterprise record services show that higher profit farms are those that consistently have good to excellent breeding performance. Management areas that have impact on breeding performance may be broadly classified to include factors related to timing (including frequency) of matings and quality of matings.

For properly timed sow matings to occur, a regular heat detection schedule must be in place. For most commercial farms this involves daily (usually morning) heat checks of all gilts and sows in the breeding groups. Use of sexually active boars by a keenly observant herdsman are the important components of identifying sexually receptive females in the heat checking process. Once females have been identified to be in heat, properly timed natural and (or) artificial matings can be performed to create the best opportunity possible for the gilt or sow to conceive and farrow a large litter.

For conception to occur, viable sperm must be in the reproductive tract of the sow a few hours prior to ovulation or the shedding of eggs from the sows ovaries into the oviduct. Standing heat typically lasts 2 to 3 days with gilts showing shorter heat periods and mature sows slightly longer periods ⁽¹⁾. However, ovulation takes place within a range of 36 to 44 hours after the onset of standing heat. Given the time relationship of these reproductive "events," we can understand why matings that occur very soon after the onset of standing heat or matings that occur very late in the heat period are less likely to be successful matings.

Since the herdsman checking heat once daily really does not know if the sow has been in heat for just a few hours or for nearly a 24 hour period, multiple matings must be performed to insure high conception rates. Research and commercial experience indicates that mating strategies that include at least one mating each day the sow is in standing heat will yield acceptable conception rates ⁽²⁾. These matings may be by natural service, artificial insemination or a combination of the two. For most sows this means that two matings 24 hours apart will occur. Failure to provide two matings spaced at this or a similar interval will reduce the chances of a successful mating.

Some studies even show that for sows showing standing heat for a third day, a third mating can increase herd conception rates slightly further. But can the use of multiple matings be carried to the extreme and actually be detrimental to conception rate and litter size? A recently published study from the University of Minnesota indicates that the answer to this question is yes under certain circumstances ⁽⁴⁾. In their study the Minnesota workers found that if a third insemination was performed 72 hours after heat was first detected, then conception rate and litter size on a herd basis was actually reduced slightly. This was particularly true for first and second parity females. This seems logical since the duration of the heat period in younger females is usually shorter than with older sows. The take home message is that two matings spaced at adequate intervals is important to achieve high herd conception rates. Third matings have the potential to improve conception in certain sows with longer than average heat periods. However, third inseminations that are performed very late in the heat period or after the heat period is over may be negative to performance.

Assuming timing (and frequency) of matings are sufficient, the consideration of quality in the mating process remains for optimizing breeding performance. Swine reproduction specialist Billy Flowers of N. C. State has published a detailed description or what high quality natural and artificial matings are ⁽³⁾.

To summarize Flower's description, the ideal natural mating process would be one in which the boar in the breeding pen with the sow would be attentive in pre-mating behavior, circling the sow while nuzzling her flanks in the process. The boar would also make vocalizations and salivate. All of these pre-mating behaviors serve in concert to stimulate the sow to assume a rigid response and in effect prepares her to "endure" the stress of supporting the boar's weight for the necessary time after mounting. For her part the sow would settle into a firm standing reflex for acceptance of the boar quickly without undue distractions or delay. Upon mounting, the boar should show little difficulty achieving insertion although occasional assistance by the herdsman would be considered normal. After a brief period of thrusting the boar settles into a breeding posture and remains in this position for a sustained ejaculation with minimal or no backflow from the sow's reproductive tract.

Counterproductive behaviors in natural mating would include overly aggressive activity by the boar such as severe biting of the sow or violent rooting along the sow's flanks. Also matings in which the boar attempts to mount too quickly without first performing some pre-mating activity to sufficiently stimulate the sow for a solid standing reflex may be considered less than ideal.

An ideal artificial mating has similar characteristics as a natural one but in this case the behavioral cues of the sow and the skill of the breeding technician are of special importance. The sow would exhibit a definitive immobilization response and the technician's placement of the breeding catheter would be such the sow's cervix would be secured around the end of the catheter. The extended semen would flow into the reproductive tract with minimal external pressure applied to the semen container and there would be little or no semen backflow from the sow's reproductive tract. The technician would take the time necessary for a quality insemination and would not become impatient and rush the process.

In summary, effective mating procedures on sow farms ultimately relate to proper timing and frequency of matings and the quality of how the mating process is performed. Producers, managers and herdsmen who make timing and quality of sow matings a priority should realize benefits in breeding performance of the herd.

By Allen F. Harper, Extension Swine Specialist, Tidewater AREC, Virginia Tech

References:

1). Diehl, J. R., and J. E. Albrecht. 1995. Managing gilts and sows for efficient reproduction. Pork Industry Handbook fact sheet PIH-8, Purdue Univ. Coop. Extension Service, West Lafayette, Indiana.

2). Flowers, W. L. 1997. Getting sows bred efficiently in modern production systems. Proceedings of the Thirtieth Annual Virginia Pork Industry Conference pp. 15-21, Virginia Cooperative Extension - Tidewater AREC, Suffolk, Virginia.

3). Flowers, W. L. 1997. Scoring natural and artificial matings. North Carolina Pork Report, Oct.1997, vol. 10(10):11, North Carolina Pork Producers Assoc., Raleigh, North Carolina.

4). Rozeboom, K. J., M. H. T. Troedsson, G. C. Shurson, J. D. Hawton, and B. G. Crabo. 1997. Late estrus or metestrus insemination after estrual inseminations decreases farrowing rate and litter size in swine. J. Animal Science vol. 75:2323-2327.