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BIG PEN SYSTEMS
Large Groups At The Grow-Out
Dr. Brian Hardy
(Abstracted from papers by Harold Gonyou and Lee Whittington, Prairie Swine Centre and Rocky Morrill, Peace Pork Inc. presented at the Banff Pork Conference,
2004)
Conventional management of grow-finish pigs has been in groups of 25-30 pigs per pen with several pens in a room. Larger production units have many animals weaned each week. This allows for separate sex, phase feeding and now the option to house pigs in large groups. The group size can be over 250 pigs per pen or sometimes as one large group of 500-1000 pigs in a room. When large group size is combined with an auto-sorting system to weigh and regroup animals, there are five main economic advantages:
- Reduction of labor costs associated with weighing and handling pigs
- Higher percentage of pigs marketed in the target weight range
- Increased utilization of barn space.
- Enhanced animal welfare
- Optimum phase feeding by weight
The general concept is to have a large common area and a separate feeding area or “food court.” Pigs move freely around the common area and are enticed to enter the food court to eat and drink. Entry to the food court is through the auto-sort scale. Using one-way gates, the pigs can be separated into heavy and lightweight categories around a mean value. Setting the auto-sort scale to a given minimum weight at the time of sorting pigs ready for market means that a load of pigs with the correct and narrow weight range can be segregated from the rest of the group and then can have feed withdrawn prior to loading. Evaluation of the advantages and disadvantages for the various facets of the system allows for a decision to be made regarding the suitability to your
farm.
a) Facility design and operation
The advantages include:
- Pigs can choose their own comfort zone and avoid aggression
- Easier for staff to move around the pen and observe the equipment and stock
- Improved stock management as the staff have to walk through the pen
- Less pen dividers lowers the barn cost and maintenance requirement
- Only need 0.25m2 floor space per pig in the food court
- Allow 3m between auto-sorter and first feeder to prevent crowding near the exit from the auto-sort scale
- Pigs lie against the walls and dung in the pen center, hence the need for fully slatted floors
The disadvantages are:
- Maintaining optimum control of ventilation in a fully slatted room
- Dunging patterns may influence the build up of solids in the pit and create specific areas of ammonia emission.
- Still need a hospital pen area
b) Equipment
The advantages include:
- Less pen dividers and therefore less maintenance and replacement cost
- Reduced feed and water lines means less cost as all the equipment is in the “food court” area
only.
- Can have 40-50 pigs per feeder and space feeders 1.8-2.4m apart
- Continuous sorting by weight allows for more accurate phase feeding.
- Reduced cost of ventilation and temperature controls as the pig chooses its own comfort area within the room
- 500 pigs per single auto-sort is possible
The disadvantages are:
- Additional equipment involved with the auto-sorting system (sorter, compressor, scale and electronics).
c) Building cost
The advantages include:
- Increased barn capacity by 10% due to less alleyways and pen dividers
- Reduced cost of alleyway, pen divisions and unusable floor area associated with pen dividers.
- Simpler ventilation system and less feed and water lines.
The disadvantages are:
- Additional cost of fully slatted relative to partial slatted floor (US$20-25/pig)
- Cost of the auto-sorter and equipment (US$5000-8,000)
d) Labor/Skills
The advantages include:
- Less time and effort spent climbing over pen dividers and weighing pigs
- Less time spent checking feeders and waterers as they are all in one area
- Washing of pens takes less time and is easier
- Prediction of suitable pig weight for market is simplified
- Less risk of injury to staff weighing and handling pigs
- Better working conditions for staff
The disadvantages are:
- Routine pen maintenance is more difficult
- More pigs attracted to staff in the pen and
this can be intimidating
- Different training needs for staff: 2 persons should work the room together
- Removal of a sick or dead pig is more difficult
- Localised build up of ammonia may be an issue for staff
- Pigs need training to go through the auto-sort. Initially leave all gates open and gradually close them all by 8 weeks when all pigs will go through the auto-sort.
e) Operating Costs
The advantages include:
- Reduced labor cost of weighing and sorting pigs
- Reduced time and water volume in washing pens by 50%
- Reduced maintenance on equipment
The disadvantages are:
- Maintenance cost of the auto-sorter and associated equipment
f) Animal Performance and Health
The advantages include:
- Over 90% of pigs in the core of the grading grid (may be worth US$5-6/pig)
- Increased uniformity of individual loads of pigs
- Less diseases (Salmonella) normally found in difficult places to clean
- Animals can escape from anti-social behavior, therefore less tail-biting
- Easier to reintroduce a pig from a hospital pen or pigs from another group
- Pigs normally go through the auto-sort 3-4 times per day after training
The disadvantages are:
- No change to variation of pig
weights within the large group relative to pigs in small pens
- Diseases spread by contact can be transmitted to more animals, more quickly
- More difficult to find sick pigs and move them out of the group
- Daily gain may be 1-2% lower in first 2-4 weeks
g) Animal Welfare
The advantages include:
- More freedom of movement
- Public perception maybe more positive
- Less fighting and aggression
- Less stress at times of moving animals
- Co-mingling is easier at anytime
- Easier to move pigs at loading time
- No increase in behavioral vices
The disadvantages are:
- Injured animals are more difficult to find
h) Pork Quality
The advantages include:
- Less stress and fighting at loading and during transportation
- Removal of feed prior to shipment is easier and more controlled
- At least 4% more pigs in the core of the grading grid
The disadvantages are:
- Finding treated pigs that must be removed prior to shipping
This was published in PIG INTERNATIONAL (Nov, 2004)
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