An effective operations manual can help barn staffs keep production facilities running smoothly.
Pork producers commonly invest hundreds of thousands of dollars in a production site, yet give little thought to sitting down and drafting an owner's manual that will ensure it operates as efficiently as possible. Such an owner's manual, for a production site or series of buildings, would contain the following chapters:
Chapter 1: Operating characteristics of the heating and ventilation system.
Chapter 2: Feed system operation, including feeder settings.
Chapter 3: Water system operation.
Chapter 4: Emergency operation procedures.
Chapter 5: Repair schedules and seasonal settings.
Note that the idea of an owner's manual does not detail the many management issues associated with daily care of the pigs, such as identification and treatment of sick pigs, nutritional regimens, vaccination schedules, marketing of pigs, etc. Rather, the manual should detail the many issues that will allow the day-to-day operation of the facility to run smoothly.
Let's take a closer look at the contents of each chapter:
Chapter 1 — Heating and Ventilation Systems
Most likely, there is no detailed explanation of how or why the various ventilation system components were chosen, or a detailed listing of the capacities of those components, or the most common settings for the ventilation controller.
Armed with fan- and facility-specific information, it is possible to predict how a ventilation system will respond to various pig sizes, pig densities and changing seasons.
Assuming insulation values of R=30 for ceilings and R=3 for sidewalls, combining pig heat production estimates with facility heat loss equations make it possible to create Table 1. The balance point temperature in the table lists the estimated incoming air temperature at which heat production equals heat loss via the ventilation system and facility perimeters, walls and ceiling at various combinations of pig weight and room temperatures.
For pigs weighing 50 lb., if the set point of the controller is 70°F, and the first stage variable-speed fan has the minimum speed set to ventilate at 5 cfm/pig (two 24-in. pit fans in a 1,200-head facility), the room is in balance when the incoming (outside) air temperature is 23°F. If the incoming air temperature is cooler than this, heat must be added or the room temperature will gradually decline.
Conversely, if the incoming air temperature is higher than 23°F., the ventilation system will gradually increase the amount of air removed (cfm), while the room temperature rises.
When the stage 1 fan(s) run at 100% speed (often 10 cfm/pig), the room temperature is 2°F higher (bandwidth setting in the controller) than the set point and the incoming air will now be approximately 45°F.
Bandwidth is used with variable-speed fans to define the number of degrees of temperature change necessary for the fan to go from the minimum speed to full speed. A common winter setting is 2°F, which means the fan increases speed from the minimum to the maximum as the room warms up 2°F. When the fan is operating at full speed, the room temperature is 2°F warmer than the set point temperature.
As Table 1 illustrates, one of the biggest ventilation challenges in many wean-to-finish facilities is getting the ventilation rate low enough for pigs weighing 25 lb. or less. The balance point changes from 22°F to 45°F as the ventilation rate increases from 2.5 to 5 cfm/pig for 25-lb. pigs. At the 5-cfm/pig rate, this means heat must be added either as room heat or supplemental zone heat whenever the incoming air is colder than 45°F vs. heat additions at 22°F with 2.5 cfm/pig.
In addition, consideration must be given to humidity levels in grow-finish facilities. Table 2 offers some guidelines for managing ventilation rates during cold weather.
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Chapter 2 — Feeding System Details
With skyrocketing feed costs, one would think that feeder management would be high on everyone's priority list. Yet, all too often, animal caregivers ignore feeder settings in their rush to complete pig observation and management routines.
Generally, many barn workers have had little training in the appropriate feeder settings for various types of feeders and stages of growth. There are several good Web sites with pictures of recommended feeder adjustments meant to help maximize growth and efficiency. One of the best is: http://www.asi.k-state.edu/DesktopDefault.aspx?tabindex=1007&tabid=889.
While helpful, an even better approach is for the pig owner and the employee to walk the pens together while discussing appropriate feeder management. When both agree on a setting or range of settings, use a digital camera to record the agreed upon settings. Print and post the pictures in the facility for easy reference.
Chapter 3 — Water System Details
Water consumption by nursery and grow-finish pigs has a distinct pattern within a 24-hour period. In thermal-neutral conditions (generally air temperatures in the pig zone less than 80°F), grow-finish pigs begin drinking water around 5 or 6 a.m. Water consumption normally peaks in early afternoon, then gradually declines the remainder of the day (Figure 1).
However, when pigs are housed in warm to hot conditions — air temperatures in the pen exceeding 80°F for one or more hours/day — they will alter their drinking pattern. Pigs will begin drinking earlier in the day and peak at 8-9 a.m. Water consumption will decline through the middle of the day, then peak again from 5 to 8 p.m., before declining again into the evening hours.
It is very important to check for waterline restrictions. Waterlines connected to drinking devices in swine facilities are almost always ¾-in., inside diameter (ID).
The Midwest Plan Service (MWPS) recommends that water supply lines be sized with a velocity of 4-ft./sec. (Table 3). Finishing pig-drinking devices should provide 3-4 cups/min. capacity. In other words, the typical ¾-in. waterline in a production facility has the capacity for no more than 22 drinking devices.
And, while many water medicators have rated capacities of 7 gal./min., many are attached to drinking water supply lines with ½-in. washing machine hose, which has a capacity of only 2.5 gal./min. (Figures 2 and 3). In some instances, restrictions in the attachment plumbing are as severe as ⅜-in., which means water flow is restricted to 1.4 gal./min.
Pressure regulators are another overlooked restriction in water delivery systems. Drinkers are often installed with line pressures of 20 psi. The intent of these lower pressures is to reduce the effort required by the pig to activate the water delivery device, thereby reducing water wastage. The formula to compute the impact of a change in pressure on flow is: √(P1/ P2).
Thus, if the supply pressure to the facility is 40 psi and the pressure reducer is set to 20 psi, the resulting flow rate is 71% of what it was at 40 psi. If you double the pressure — from 20 psi to 40 psi, for example — the flow increases 41%, assuming there are no other limits to flow in the delivery system.
And, don't forget flow restrictions associated with water meters. Many builders install water meters with ⅝-in. internal capacity, which means the capacity of the meter (and drinking waterline) is only 3.8 gal./min.
Final restrictions in water delivery systems are filters. The location of the filters may make them very difficult to routinely flush or clean. Often, regular maintenance of the filters is not planned for.
Chapter 4 — Emergency Operation of the Facility
Alarm systems and fail-safe devices should be tested on a routine basis — weekly or monthly, depending on the system — to verify operation of the system's devices. Test results should be recorded in a written log. If a catastrophic event occurs at the site, this written log makes it more likely that an insurance claim for losses will be resolved in a timely manner.
Ventilation controllers are mini-computers and are subject to failure due to electrical voltage spikes, lightning, etc. Every animal space that has the ventilation system controlled with an electronic controller should have mechanical override thermostats installed in the space. One thermostat controls the heating system and is set no closer than 5°F below the set point of the ventilation system. The other thermostat(s) is designed to provide heat relief, and is often set to activate one or more fans or curtain drops when air temperatures are in the range of 85-90°F in the facility.
Chapter 5 — Seasonal Maintenance Logs
As production systems grow larger, and the number of people responsible for the various components of the system increases, the seasonal maintenance tasks are often overlooked. Written checklists that apply to a specific site or facility will help insure that these routine tasks are accomplished. The supervisory staff should verify completion of these tasks.
Making the Manual Useful
Once the manual is written, either as a formal document or as a series of notes, put it with the equipment manuals for the site in a location where it is readily accessible to anyone responsible for operating the systems effectively. A records storage case (plastic preferred) is often used to assemble all documents and manuals in one location. The storage case should be water- and rodent-proof, yet provide on-site access to everyone who may need to access this vital information.