Managing the mating program for maximum throughput without creating pig flow problems requires good forward planning to achieve consistency.

Calculate the entry to exit time per crate in days e.g.

• 3 days cleaning time
  4 days entry to farrowing
  

Total = 28 days

In theory therefore each crate could be used 365 ÷ 28 = 13 times per annum. Calculate the actual number. This will indicate the efficiency of use.

• Maintaining regular batch farrowings each week, or each farrowing period, is dependant upon the following:
• Sows coming into oestrus regularly after weaning.
• A good conception and consistent farrowing rate.
• A knowledge of the farrowing rates weekly or monthly.
• A planned input of gilts to replace culled sows.
• Anticipation of oestrus in the gilts.
• Planning at least 8 weeks ahead to determine the breeding females that will be weaned and due for mating.
• The effects of disease.
• There are a number of management tools that can be used:-

1. Modern computer programmes will list out sows that fail to maintain a pregnancy on a week by week basis. (Fig.3-29). This format can also be carried out manually from the weekly mating sheets. When sows reach their twelfth week of pregnancy (forecast week) those animals still pregnant, viable or those due to be culled for age or disease can be identified. This will indicate those available for mating in 7 weeks time. The anticipated matings can be brought to target by planned gilt matings for that week.

2. Fig.3-30 shows a farm example on a weekly basis whereby production is monitored against the cumulative targets. Such a method gives an opportunity to manipulate the system if there is a major loss and compensate for it.

3. For small herds up to 350 sows a circular calendar can provide an excellent and simple visual method. Sows due for culling can be identified by a colour code. In this particular herd summer infertility is a regular phenomenon with increased matings carried out to compensate and disadvantaged sows culled.
4. Another option to maintaining the programme is to serve all sows weaned each week and cull some sows 3 1/2 weeks later to adjust the number of pregnancies to those required.