Control Water Leaks To Manage Manure
By Dr. Mike Brumm, Brumm Swine Consultancy, Inc.
The long, wet fall is becoming a distant memory for Midwestern pork producers. For many pork producers, this fall presented a host of challenges, not only those challenges associated with corn and soybean harvest, but also the challenges of full manure pits with limited application areas available. In many cases, planned late September pump-outs were delayed until October or even mid-November. This often resulted in compromises in pit ventilation as manure levels came ever closer to the bottom of the slats and phone calls to custom manure haulers became ever more frantic.
Many readers of this article are vowing ‘never again’ as they make plans to modify their facility management or timing of manure removal in future years. While I can’t offer advice in this article on the many issues associated with the timing of manure removal, I can give readers solid information on in-barn management decisions that will impact the amount of manure that must be stored in the pit until the next removal event.
While the manure stored in deep pits is comprised primarily of manure and urine excreted by the pigs, another often major source of material going into storage pits is wasted water. Once a facility is built and feeding and drinking equipment installed, the major determinant of how much excess water enters manure storage devices such as deep pits is drinker management.
In a conversation with managers in a Midwest production system last summer, there was speculation as to the impact of leaking drinkers on manure volume. To test this, I set my kitchen faucet to drip at 15 drips every 10 seconds (90 drips per minute). This drip rate amounted to 20 ml per minute. Note that at this drip rate, you can still count the drips so you would not consider this to be a major leak in a production facility.
In addition, this rate doesn’t seem like much when you consider that drinkers in grow-finish facilities are most often set to deliver 750-1000 ml per minute (3 to 4 cups per minute). However, in 24 hours, 90 drips per minute totals to 28.8 liters or 7.6 gallons of wasted water.
If it costs $0.012/gal to have a commercial manure pumper haul and inject manure from your facilities, every drinker dripping at 90 drips per minute for 24 hours costs $0.09 per day in manure disposal costs, with no benefits from N, P or K being added to the pit. This is in addition to lowering your capacity for storage of feces and urine.
In a classic study at the Prairie Swine Centre in Canada, Dr Harold Gonyou and co-workers examined how much water is wasted by pigs in the drinking process with nipple drinkers. When drinking water flowed at 1300 ml (5.5 cups) per minute, a 120 lb pig swallowed at a rate of 795 ml (3.34 cup) per minute with the remainder (505 ml or 39%) being wasted. If the flow rate was lowered to 650 ml, the swallowing rate decreased to 467 ml (1.96 cup) per minute, but now wastage decreased to only 28% of the flow. There was no difference in pig performance between these flow rates.
Based on evidence such as this, the flow rate for drinking devices in grow-finish facilities is recommend to be set at 750-1000 ml (3-4 cups)/minute. The evidence suggests that if water is made available to the drinking pig faster than this, wastage increases. Currently there is no evidence available to suggest that nipple drinkers should be set to a different flow rate from bowl drinkers or from wet/dry feeder or tube feeder drinkers.
Pressure is another water system component that has an impact of both flow rate and potential wastage. In general, most manufacturers of bowl and nipple drinking devices recommend water pressures of 20 psi to the devices. At this pressure, the smaller pig can easily regulate the water delivery device. If pressures are too high at the device, smaller pigs may have to exert un-due efforts to activate the device, resulting in flows that are too rapid for the pig to consume and increased wastage. On the other hand, if pressure is too low, flow rate is reduced, and in some devices the delivery mechanism may not seal properly, resulting in increased wastage from leaking drinkers.
For those that have installed the relatively newer style of ‘bladder’ drinkers, several manufacturers are now recommending 40 psi for water line pressure. Apparently these higher pressures reduce bladder leakage problems and some have reported fewer bladder repairs at this pressure. In the case of ‘bladder’ drinkers, pressure at the drinking device is not related to pig drinking behavior and water wastage as these drinkers have a pan with a water reservoir (often ½-1” deep) from the pigs to drink from.
Readers of this column are reminded that as pressure is reduced, the volume of water delivered is reduced. If pressure is reduced 50% (using a pressure reducer set to 20 psi for a drinking line when incoming pressure is 40 psi), total water volume is only 71% of what it would be at the original pressure. If the pressure is reduced to 25% (10 psi in a drinking line with incoming pressure of 40 psi), flow is only 50% of the original capability.
Dr. Mike Brumm is the owner of Brumm Swine Consultancy, Inc. of North Mankato, Minnesota. He was previously a professor at the University of Nebraska. Dr. Brumm's areas of expertise include management and housing of the growing pig, industry issues including production networks, contracts, cost of production and record systems.
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