Pork producers in our client base are searching for predictable, efficient growth with every insemination in the breeding barn and with every load of weaned pigs. These clients have challenged each other to improve production and identify those drivers of efficiency that have allowed them to produce more pork with less work and cost and to generate more profit.

This article will discuss recent advances and some of the simple math behind our decisions.

From Sows to Weaners

One simple strategy many of our smaller clients have adopted is to stop breeding sows and join a weaned-pig sow center. The sow centers have afforded them the opportunity to focus on on-farm milling and efficient growth of all-in, all-out (AIAO) pig flow and update facilities while still reducing total labor needs.

Apart from labor and economics of trips for the sow center, pig growth and single-filling barns greatly enhance facility throughput.

Larger producers are looking at the same flow dynamics. A producer with a 1,200-head barn or a 2,400-head site wanting to single-fill is considering ownership in a larger 5,000- or 6,000-sow farm. A 6,000-sow farm producing 22 pigs/sow/year can easily fill a 2,400-head site/week with all barrows in one barn and all gilts in the other.

Greater sow herd efficiencies have allowed our 6,400-head site at 24.5 pigs/sow/year to produce over 3,000 pigs each week.

Producing 3,000 pigs/week would allow that producer with a 2,400-head barn site to fill half of the site with barrows and half with gilts, all within seven days of age. Plus, he could meet the needs of another producer-member in the group requiring a 600-head barn site filled in that same week.

Logistics requires a balance of all the producers in the group so that an even, predictable schedule will meet the pig flow requirements of the entire group.

Balancing these sow herd efficiencies with barn site fill time and barn flow requires a great deal of communication and cooperation.

Later Weaning Challenges

Our challenge as a management service and production system is to weigh the benefits of increased lactation length on the overall production of the entire system.

Producers throughout the industry have moved quickly toward increasing lactation length. In 2003, Kansas State University (KSU) aggressively promoted its benefits: nearly $0.90/pig/day of age as average lactation length increased from 15.5 to 20.5 days. This was highly predictable, highly repeatable research that we have begun to implement within our production system.

In general, the research says that nearly $1 a day for each day of weaning over 15 days is predictable as you get closer to 21 days of age. This is value provided throughout the growing period.

The KSU research also evaluated mortality, with a predictable difference of up to 4% in group mortality.

Going All-In, All-Out

AIAO is seen as an absolute requirement for growing pig facilities. Hotel-style nurseries with several rooms lining a hallway have even come into question in efforts to reduce the spread of respiratory disease. The chief concern is limiting the spread of porcine reproductive and respiratory syndrome (PRRS) virus, and most critically, managing the disease in PRRS-positive sites.

For that reason, AIAO has been a generally accepted practice for years. We have now begun to add further “gold standards” in our production system, with such critical control points as minimum age and weight.

In our system, 16-day minimum age and 7-lb. minimum weight are weaning targets. This will soon be changed to 18-day minimum age and 8-lb. minimum weight.

Increasing Weaning Age

Cate Dewey, DVM, University of Guelph, Ontario, and others have given talks on increasing weaning age without adding farrowing crates. She addressed several limits to farrowing utilization in 2001 at the American Association of Swine Veterinarians annual meeting:

  • Increasing number of times weaned per week

    Minimum age drives the total improvement in lactation length. You will not be able to improve more than 0.5 days in average lactation length by weaning more than twice per week.

  • Reducing the number of days loading time prior to farrowing

    Decreasing load time prior to farrowing is somewhat risky in a fully productive breeding barn because the system, in essence, is already full. Moving time is often two to three days prior to farrowing, depending on the number of weanings per week. Inventory of prefarrow sows at any given day will allow you to monitor this practice and manage the farrowing barn appropriately. Reduction to three days prior to farrowing would be ideal if you are weaning three times per week. If weaning twice per week, it may be necessary to load up to five days prior to farrowing with a range of three to five days.

  • Restricting split weaning and bump weaning

    Split weaning is a common practice to improve wean-to-estrus interval and pig weaning weights by essentially reducing the number of piglets on the last three to five days of lactation. However, this practice does pull younger pigs ahead and reduces the lactation length of those piglets. Bump weaning is also common and requires high-quality, mid-lactation nurse sows. Bump weaning should be restricted when lactation length is already tight and weaning age has been reduced to the minimum age.

  • Adding farrowing crates

    This is certainly the only predictable way to achieve increases in the production of high-quality pigs.

Denmark's swine industry has maximized later weaning strategies by driving all lactation to above 21 days. Gilts are commonly lactated over 30 days.

Additional farrowing crates are necessary in most modern U.S. systems to exceed 16 days lactation.

Farrowing Economics

Table 1 on page 23 describes two options for determining farrowing crate utilization.

The most common way to determine the necessary number of farrowing crates in a production system would be to calculate the desired farrowings per week and simply provide enough farrowing crates for three groups in the farrowing house.

For example, if total crates available were to be three times the farrowing target, your common farrowing target would be the desired number of farrowings per week based off of the sow herd inventory.

As shown in Option #1 in Table 1, many producers in our system were looking at 2.45 litters/sow/year as an optimum and predictable number for their system. For example, in a 2,400-sow farm, 2.45 litters/sow/year would require 113 litters farrowed/week. The 113 farrowings/week and 360 farrowing crates were thought to be the proper parameters to provide three full weeks of farrowing crate capacity.

But several concerns surfaced. Most notable was that while the 14-day minimum lactation length was a predictable number that we could manage, the number of total sows farrowed/week varies both with season and farrowing productivity. When 120 sows were farrowed/week, we were still able to maintain that 14-day minimum. However, the average lactation length and number of litters weaned/week were increased in an effort to keep this minimum in place. We also found this approach produces too little predictability and too much variability.

Option #2 in Table 1 is the use of desired lactation length as opposed to desired farrowings/week to drive farrowing capacity. Desired lactation length of 14 days, plus the spread in ages of litters weaned/week and the average prefarrow load days, led to a different calculation method. This calculation adds the minimum lactation length, spread of weaning ages/week and average number of load days prior to farrowing, then divides the sum by seven (days in a week).

For example, a minimum lactation length of 14 days, plus a spread of 3.5 for two weanings/week and the additional three days for an average prefarrow loading, equals 14 plus 3.5 plus 3 divided by 7. This calculation provides the 2.92 (or roughly 3) factor, which made us feel three was the appropriate number for providing three full weeks of sows, or three full farrowing groups in the farrowing house at any one time.

We now know that we would want a minimum lactation length of 18 days and a spread of 2.33. Using this calculation, 18 days of minimum lactation plus 2.33 (7 days divided by 3 weanings per week) plus 3 days of prefarrow loading time, on average, requires at least 3.3 available groups in farrowing.

From this math, we conclude that if our 2,400-sow farm needs to reach 113 farrowings/week to meet our desired litters/sow/year, then we need to provide at least 373 farrowing crates on this farm (113 farrowing crates times 3.3 groups).

Our calculation would also tell us that if we add one more 24-crate farrowing room, we are then simply providing 397 total farrowing crates, using our 3.3 factor for groups. We can farrow 116 sows on a weekly basis and still not have to lactate any sows for less than 18 days.

If this farm runs at two weanings/ week instead of three, we will need to use 3.5 as the farrowing group's total, which would push our total crate needs over 397.

Farrowing Crate Economics

As with all decisions in swine production, economics must be balanced along with production. The economics of adding 24 farrowing crates was $2,300/farrowing crate, or $230/pig space, based on 10 pigs produced/litter.

In that system, those additional pig spaces made perfect sense if we were able to achieve that $1/day payback for every day we exceeded that 15.5 average lactation length. We simply went from a 15.5 to an 18.75 average lactation length, or $3.20/pig value on every pig that would be added back for the investment of $55,200 (24 more crates at $2,300/crate). At 22 pigs/sow/year on a 2,400-sow farm, the investment of $55,200 brings greater value of $3.20/pig on 52,800 pigs in the first year. The payback time is less than six months.

Note that nothing was factored in for improved sow productivity. Sow herd fertility improves wean-to-service interval, litter size and overall herd productivity.

Performance Targets

To judge performance of those growing pigs, review performance targets within the system and where the system is going (Table 2). A 12-lb. weaning weight would provide many producers with a high-quality pig easy to start, and present little challenge within that first five to seven days coming on feed.

Just two years ago, producers were looking at 10- and 11-lb. average starting weights. Our top 10% goal would be to bring these producers a 14-lb. pig as quickly as we can move it into the system. This 14-lb. pig would include a 20-day average lactation length in our system, based on a change of 0.5 lb. of weaning weight for each additional day beyond 15- to 16-day lactation lengths.

Average Daily Gain's Impact

The greatest number driving productivity and throughput is average daily gain. Monitoring daily gain is a tool we are only now beginning to understand with automatic sorting technology or even simple portable scales.

This technology established that a single-fill population close in age at start time, as well as optimum in weaning weight, would lead to less variability throughout the group. Combining that with appropriate feeder and water space and square footage for growth should result in a uniform population on the right path to ideal growth.

Research trials from both Mike Brumm at the University of Nebraska and Noel Williams with PIC have provided guidance in determining both the ideal welfare and environment for optimum, profitable performance throughput for the system.

Brumm has shown that pigs will require a minimum 1.5 in. of stainless steel dry-feeder space/pig in our system. What this means is that each 14-in. dry-feeder hole can support nine pigs. Pens with 25 pigs/pen have a three-hole feeder available. Pens with 50 pigs/pen are allowed both sides of a three-hole, dry feeder.

This 1.5 in. of stainless steel feeder space/pig is the same whether you are talking nursery pigs or finisher pigs.

As with the feeders, no more than 25 pigs are started on a drink cup or nipple waterer. Many producers using swinging waterers have two nipples available, but we still have to recognize that this may, in many cases, provide only one available drinking space.

Managing to Reduce Variation

In many of the automatic sorting systems, we have gone to 2 in. of stainless steel dry-feeder space/pig.

PIC's Williams has provided us with both the tube and dry-feeder recommendations. PIC requirements with our pigs have led us to a minimum of 2 in. of trough space/pig with tube feeders and a maximum of 11 pigs/tube feeder. Tube feeders serve as a competitive feeding environment as opposed to dry feeders, and therefore, additional space is necessary in this system.

As we evaluate growth and variation within the system, we still have to get back to start weight and fill time and their effect on variation for the population. Refer to Figures 1 & 2.

In evaluating start weight variation, recognize that the standard deviation of early-weaned pigs has commonly been placed at 2 lb. In a bell-shaped curve of a normal population, with a 12-lb. average weaned pig, 2.5% of that group will still fall in the 6- to 8-lb. range.

What this means is that for an average load of 1,000 pigs delivered, with an average weight of 12 lb., there will still be 25 pigs that fall between the weight range of 6 to 8 lb. If we don't want any pigs less than 7 lb., then it is critical to find a method to reduce variation, either by removing the pigs or providing them a way to gain additional weight prior to starting in the nursery.

Weaning Variation

Nurse sow and bump wean activities are most common if farrowing crates are available. However, we still need to recognize that it is a normal population, and variation is going to begin at weaning time.

University of Minnesota's John Deen, DVM (See “Solutions to Control Variation,” p. 30), has shown that a 7-lb. pig at weaning time is three times more likely to die in the nursery. A 2-lb. entry variation becomes a 10-lb. variation at slaughter.

Accepting these simple rules of thumb, it is then necessary to do our very best at reducing variation at the earliest stage possible, providing the best environment and facilities throughout the pig's life.

Earlier Move to Finishing Profitable

The growth rate of an early-weaned pig is by no means a bell-shaped curve. We recognize that the aggressive growth phase may certainly be compromised by square footage reductions in the nursery phase.

A few producers in our system are now looking at moving pigs out of the nursery earlier and providing additional finishers or finisher spaces in an effort to maximize the growth phase of today's high-lean pigs. What this means is that pigs are achieving 2-lb./day average daily gain in the 50- to 250-lb. growth period. Therefore, it becomes detrimental to have a 70-lb. pig at 3 sq. ft., sacrificing this aggressive growth potential. Some of our clients have moved these pigs at 6 to 6.5 weeks of age into 7.5 sq. ft./pig space to maximize their growth potential.

In a 25.5-week system, or at 8.5 weeks in the nursery phase, this change would mean that a system of one nursery and two finishers now becomes a system of one nursery and three finishers. The nursery is simply run at 6.375 weeks, and three separate finishers house pigs for 19 weeks. This approach is paying dividends to our clients.

Other clients have looked at reducing pig space from 7.5 sq. ft. to 7 sq. ft. The change has brought behavioral and daily gain differences in our production system. Anything under 7.5 sq. ft./pig has become detrimental to the productivity of pigs in our system.

Table 1. Farrowing Crate Calculations

Option #1: Farrowing Crates Available — The decision is driven by the desired number of farrowings/week.

Total number of farrowing crates divided by the desired number of farrowings/week

Calculation: (Herd size X 2.45 litters/sow/year ÷ 52 weeks in a year)

Example: 2,400 sows X 2.45 ÷ 52 = 113 farrowings/week

Results: 360 farrowing crates (per room) ÷ 113 = 3.18 ratio (number of weekly groups in farrowing at any one time)

Option #2: Lactation Length — The decision is driven by the desired minimum lactation length.

Calculation: Minimum lactation length + age spread + load days ÷ 7

Age spread = 7 (days in a week) ÷ the number of times pigs are weaned/week.

Load days = the number of days prefarrowing for sows in a farrowing barn (three days is a common number of load days if pigs are weaned three times/week)

Target: 3.3 ratio allows a 17-day minimum lactation length/pig

3.5 ratio allows an 18-day minimum lactation length/pig

Farrowing target X formula = the number of farrowing crates necessary per room to achieve a minimum lactation length/pig

Example: 113-day farrowings/week target

X 3.3 ratio = 373 crates (17-day minimum lactation length)

X 3.5 ratio = 396 crates (18-day minimum lactation length)

Table 2. Performance Targets
Current Production Top 10 Target
Average weaning weight 12 lb. 14 lb.
Average weaning age 16 days 20 days
Average daily gain (wean-to-finish) 1.65 (1n + 2f)a 1.70 (1n + 2.1f)b
Average daily feed intake 3.97 lb./day 3.97 lb./day
Feed:gain 2.4 lb. (1.4 n + 2.7f)c 2.34 lb. (1.4n + 2.48f)d
Slaughter weight 270 lb. (156 days on feed) 280 lb. (156 days on feed)
a1n=1-lb. average daily gain in nursery rooms and 2f= 2-lb. average daily gain in finishing facilities.
b1n= 1-lb. average daily gain in nursery rooms and 2.1f= 2.1-lb. average daily gain in finishing facilities.
c1.4n=1.4 lb. feed:gain in nursery rooms and 2.7 lb. feed:gain in finishing facilities.
d1.4n=1.4 lb. feed:gain in nursery rooms and 2.48 lb. feed:gain in finishing facilities.