# Determining the number of pens and stalls required in a pig unit

One objective in planning a pig unit is to balance the accommodation between the various ages and number of pigs. Ideally, each pen should be fully occupied at all times, allowing only for a cleaning and sanitation period of about 7 days between successive groups.

In the following example the number of different pens required in a 14-sow herd, where 8 week weaning is practised, will be determined.

### Determine the farrowing interval and number of farrowings per year.

- Average weaning to conception interval 20 days
- Gestation 114 days
- Suckling period (7x8 weeks) 56 days
- Farrowing interval 190 days

Number of farrowing per sow per year

### Determine the number of farrowing pens

The piglets remain in the farrowing pen until 12 weeks of age.

- Before farrowing 7 days
- Suckling period 56 days
- Rearing weaners 28 days
- Cleaning and sanitation of pen 7 days
- Occupation per cycle 98 days

Thus one farrowing pen can be used for farrowing per pen.

A 14 sow herd with an average of 1.9 farrowings per sow and year requires farrowing pens.

### Determine the number of servicing / gestation pens.

- Average weaning to conception interval 20 days
- Gestation period less 7 days in farrowing pen 107 days
- Cleaning and sanitation of pen 7 days
- Occupancy per cycle 134 days

Thus one place in the servicing / gestation accommodation can be used for:

365/134 = 2.7 farrowings per year

With a total of 27 farrowing a year

27/2.7 = 10 places would be required.

### Determining the number of places for replacement stock

Presume the sows on average get 5 litters, then 20 percent of all litters will be from gilts.

- Rearing of breeding stock (12 to 35 weeks) 168 days
- Gestation less 7 days in farrowing pen 107 days
- Cleaning and sanitation of pen 7 days
- Occupancy per cycle 282 days

About 30% more animals are separated than the required number of gilts thus the required number of places in the 14 sow herd will be

### Determining the number of places in the growing / finishing accommodation:

**One stage finishing**

- Fattening of pigs 12 to 27 weeks of age (25 – 90kg) 105 days
- Extra period for last pig in the pen to reach marketable weight 21 days
- Cleaning and sanitation of pen 7 days
- Occupancy per cycle 133 days

Assuming that 8 pigs per litter will survive to 12 weeks of age the number of places required in the finishing accommodation will be:

That is 8 pens with 10 pigs in each or 10 pens if each litter should be kept together.

**Two stage growing / finishing unit:**

Growing pigs 12 to 20 weeks of age will occupy a growing pen for 63 days including 7 days for cleaning.

places are required in the unit.

Finishing pigs 20 to 27 weeks of age will occupy a finishing pen for 70 days including 14 days emptying period and 7 days cleaning ( the emptying period will be shorter if the pigs are sorted for size while being transferred from the growing to the finishing pens)

places are required in the unit.