The Nursery Feeding "Window of Opportunity"

by 5m Editor
13 March 2003, at 12:00am

By Gawain Willis, Peter Wilcock, Primary Nutrition and Steve Jagger, Associated British Nutrition plc. - We only get one chance to transition the newly weaned pig from sow's milk to dry diets. When diets fed during this critical first two weeks postweaning are highly digestible and avoid the use of soybean meal, because of appropriate use of milk proteins and cooked cereals, then those diets will allow pigs to be more productive all the way to market.

Every extra pound gained in the nursery may translate to 2-3.5 extra pounds at finish.

In a series of commercial trials, we demonstrated that pigs fed only limited quantities of high energy, highly digestible diets were able to translate that early good start into an extra 3.16 lbs of nursery weight gain. That translated to an extra $2.50 value of the pig at slaughter. After deducting extra costs, that still more than doubles the average net return seen by farrow to finish producers over the 11 year period from 1991-2001.

With such narrow pig production margins, it is easy to see why high tech, high performance diets are increasingly finding their way into common commercial practice. Early nursery diets are clearly an area in commercial swine production that can have significant economic impact on the whole production enterprise.

Because of their contribution to overall pig performance and economic returns, early diets deserve more careful attention from swine production and nutrition experts.


Increasingly, swine producers are faced with decisions that affect the profitability of their operation for months at a time. Often, there is only a narrow window of time during which those decisions can be taken. This situation occurs in most aspects of the swine business from markets and pig management to disease and nutrition. Some of these decisions are very obvious to us. Take choice of genetics suppliers or hitting the correct timing to buy ahead on corn or perhaps having extra gilts coming-on to cover poor return to estrus of sows during the summer months.

The focus of this article is on one of the less obvious "window of opportunity" decisions we have; effective nursery feeding programs. While most of the concepts discussed in this article are not new, our drive to reduce feed cost too often leads to inadequate nutrition during the first few critical days post-weaning.

We only have one opportunity to get the newly weaned pig off to a good start. Doing that job correctly can pay big dividends over the entire period from weaning to finishing.

Rapid Growth:

Intuitively, we know that weaning heavier more uniform pigs and having that maintained through the nursery period results in better growing-finishing performance. It has proven a little more difficult to confirm that intuition with data in every case, as the variation in production data can become quite large by slaughter weight, but several recent datasets do support that view (Smith, 2002, Chang, 2002 and Broom, 2002).

These workers demonstrate that for every 1 lb extra weight out of the nursery, producers should expect between 2.0-3.5 lbs extra at today's market ages. Not much you say? It is very reasonable to see and extra 2 lbs at about 9 weeks of age from pigs that get off to a very good start post-weaning. Using these datasets, that translates to 4-7 lbs at finish. An extra $1.60-2.80/hd (assuming a $0.40 live market price) can sure be welcome, especially when extra costs are low enough to have most of that drop to the bottom-line.

It can be challenging to achieve high levels of productivity during the nursery period, especially when diseases like PRRS, have been so prevalent. If, however, we step back and take stock of the young pig at weaning and his special needs, then solid performance is not so hard to achieve, in reasonably healthy pigs.

Nutritional challenges:

Prior to weaning, the young pig is well adapted to his diet of sow's milk, with only minimal exposure to dry feed. The challenge then becomes moving the piglet from a liquid diet of milk protein, lactose and fat to a dry diet largely of corn and soybean meal. While adaptation to simple dry diets occurs quickly, appropriate nutritional management through the use of complex diets during the critical first 10-14 days post-weaning is the difference between top third and bottom third performance.


Fig. 1 Enzyme Development Postweaning

The newly weaned pig is poorly equipped to digest starch and complex carbohydrates. It takes 2-3 weeks for his starch digesting enzymes, like amylase, to develop (Figure 1). If the newly weaned pig must extract a high proportion of its energy supply from starch contained in the grain portion of the diet, his performance will suffer. In order to help maintain his effective energy supply early post-weaning diets are often supplemented, in a step-down fashion, with fat, cooked cereals and simple sugars to maintain good energy supply as the piglet adapts to starch.

Commonly used sources of energy are processed cereals like steam-rolled oats or kibbled corn, and simple sugars like lactose from whey or whey permeate. The performance benefits of these raw materials are shown in Figures 2-3. The largest mistake made with energy sources is inclusion of regular "uncooked" corn too early and at too high a percentage of the diet until the pig has been weaned for 10-14 days.

Fig. 2 Effect of Processed Cereals

Fig. 3 Effect of Carbohydrate Sources
21 - 28 days of age

Fats sources are typically soybean oil, corn oil, choice white grease or lard. The newly weaned piglet handles fats fairly well, but he will digest shorter chain and more unsaturated fats better than longer chain saturated fats for the first few weeks post-weaning (Figure 4).

Fig. 4 Effect of Fat Sources

Total energy content of diets during the early post-weaning period is critical. While older pigs can quite easily adjust their feed intake to maintain fairly constant total energy intakes across a wide range of dietary energy levels, the young pig is much more limited. Often young pigs will show reduced gain as energy levels fall, as can be seen from the ABN trial data shown in Figure 5.

Fig. 5 Effect of Dietary Energy Level the First 10 Days Post-weaning
21 - 31 days of age


Most of the issues around protein/amino acid nutrition of the newly weaned pig center on sources of protein supply, rather than on total and balance of amino acid supply, the needs for which are now well documented (e.g., NRC, 1998 and Goodband,1997). Proper choice and use of protein sources for the newly weaned pig seems to be poorly understood, at least in common practice.

While on the surface proper choice of protein sources for young pigs can sometimes look more like voodoo than science, it really boils down to two important guiding concepts. That is, digestibility and antigenicity (especially in the case of soybean meal). Commonly used protein sources are whey proteins, dried skim milk, fishmeal, plasma, blood cells/blood meal and various soy products.

As the pig ages, the choice of protein source can easily be made on a cost substitution basis (assuming a formulation tool that formulates diets to acceptable standards for digestible amino acid supply and profile). However, digestibility of protein sources is generally based on trials using much older pigs, which may not adequately reflect the digestibility for the pig the first 1-2 weeks post-weaning (Jensen, 1997, Fernandez, 1986 and Goeff and Noblet, 2001). That coupled, to the immune stimulation and gut damage associated with soybean meal (Dreau,, 1994, Stokes, et. al., 2000, Benamouzig,, 1999 and Dreau,, 1995), drive protein choices more toward, milk proteins and other highly digestible animal and plasma proteins (e.g., Figure 6 and de Rodas, 1995, Gatnau and Zimmerman, 1990, Hansen, 1993, Dritz,, 1994 and DeRouchey, 2002).

Fig. 6 Milk Protein vs. Soybean Meal

Really the whole concept of feeding the newly weaned pig during his first 2 weeks post-weaning boils down to allowing him to achieve high absorbed levels of balanced amino acids and effective energy. In large measure that means diets that are nutrient dense, highly digestible and not damaging to his gut and immune system.


Ok, so what? No matter how much we scientist talk about the way to do things, producers still want proof in practice. We recently completed a series of field trials under commercial conditions to determine if these concepts really do translate into cost effective extra gain during the nursery period.

These trials were run across several states under varying conditions. Some involved fairly small groups of pigs while others were quite large involving several thousand pigs. The standard feeding program at each commercial unit varied, but included several prominent feed supplier programs as well as the most popular university programs. The test programs also varied to some extent because of unit differences in weaning ages, disease status and production practices.

However, all the test programs used fairly high levels of milk protein (especially in the first diet) and only cooked cereals with no uncooked corn. Energy densities were quite high generally in the 16 MJ/kg DE. If soybean meal was utilized at all in the test programs, it was at not more than 10% of the diet and not until pigs had been weaned for a week and achieved 15 lb average weight.

The study outlined in Table 1 below is typical.

Each week, as pigs were weaned (at about 17 days of age) they were split into 2 different groups and offered either the unit's regular rations or the test program. In this case, pigs were fed 1 pound of the first diet, 2 pounds of the second diet and 3 pounds of the third diet, followed by the unit's regular program fed for the remainder of the trial. Some important points reveal themselves in this trial.

First, the whole idea of meeting the pig's early needs without compromising his digestive or immune system is that the benefits carry forward. In this case, the extra 0.9 lb body weight seen from feeding the test diets during the first 11 days continues to widen to 2.2 lbs in the next 10 days and finally to 4.96 lbs by the end of the trial.

Secondly, this was accomplished by feeding only about 6 lbs of product over the first 10 days post-weaning. At this unit, feed costs for the first 11 days were around sixty cents higher for the test feeding program, but that still left something more than $3.20 net return to the producer (at $0.80/lb for extra gain).

So what does this study show us? First there was, as expected, an immediate benefit with the complex diet in the first 10 days post weaning. This is the result of the trial diets containing higher levels of milk protein and cooked cereals resulting in greater feed digestibility and thereby performance.

In addition the lack of soybean meal in these early feeds ensured that the test pigs did not become immune activated thereby diverting important nutrients such as energy and amino acids from growth into maintenance of the gut structure and immune functions. Earlier work has also shown that higher energy intake immediately post weaning maintains villus height while lower energy intakes have an adverse effect (Pluske et al 1996a, 1996b).

The combination of these principles found in these high density complex diets results in the improved performance shown when compared to a typical commercial feeding program. The benefit of the complex feed is carried forward after the pelleted feed has been fed with a further 10% improvement in ADG in the next 10 day period and another 11% improvement in the following 20 day period. Again this shows that when the newly weaned pig's early nutritional needs are met without compromising his digestive or immune systems, then the performance benefits are carried forward.

A general summary of 9 field trials (Figures 7-9) conducted over the last 6 months of 2002 using diets and feeding programs based on these principles reveals that producers have the opportunity to cost effectively improve nursery performance.

On average, these trials show average daily gain was improved by 8.5% and feed efficiency was improved by 5.7%. For the 5 trials that had complete nursery periods, out-weights were improved by 3.2 lbs, which would generate an extra $2.50/pig (assuming a value of $0.80/lb). Average extra feed cost for these trials was about $0.50 leaving about $2.00 dropping to the unit bottom line. Not surprisingly, mortality was also improved during these studies by an average of 1.2% units. Based on the last 10 years average profitability per head, an extra 1.2% pigs sold would add about $2000 profit for each 5000 sows of production.

Fig. 7 Commercial Trial Summary of Average Daily Gaina

Average improvement 8.5%
a - Test program pellets (average: 6 lbs) were fed prior to being fed the unit's regular ration for the remainder of the trial period
b - Note: Trial 7 was severely disease challenged

Fig. 8 Commercial Trial Summary of Feed Efficiencya

Average improvement 5.7%
a - Test program pellets (average: 5.5 lbs) were fed prior to being fed the unit's regular ration for the remainder of the trial period

Fig. 9 Commercial Trial Summary of Extra Nursery Weight Gaina

Average of an extra 3.1 lbs or $2.52 a pig
a - Test program pellets (average: 5.5 lbs) were fed prior to being fed the unit's regular ration for the remainder of the trial period

The Opportunity:

It is becoming increasingly difficult to add production capacity through new construction. That suggests we need to produce more pork from the facilities already in place.

As we have shown in this article, one excellent way of increasing production output is by getting newly weaned pigs off to a better start, which results in more pounds sold at market.

Clearly, controlling nursery feed costs was an area that needed focus over the last few years. The information in this article simply asks the question whether we have gone too far by failing to recognize the window of opportunity we have to allow the newly weaned pig to express more of his growth potential as he transitions from sow's milk to dry diets over the first two weeks post-weaning.

Our work suggests that many units have gone too far in lowering costs via simple diets and will actually make more money from a reexamination of their early nursery feeding programs.

It is very important to improve overall digestibility of our early nursery diets through appropriate use of highly digestible milk proteins and cooked cereals, while limiting the young pig's exposure to dietary antigens from soybean meal.

The Iowa State Production Enterprise system estimates that the average net return for farrow to finish operations over the years 1991-2001 was about $1.78/hd (Anon, 2003). With such narrow margins, it is clear to see why easy to implement nursery feeding strategies that offer net return values that would double the average net return seen over the last 11 years are increasingly finding their way into common commercial practice.

Early nursery diets are clearly an area in commercial swine production that can have significant economic impact on the whole production enterprise.

Because of their contribution to overall pig performance and economic returns, early diets deserve more careful attention from swine production and nutrition experts.


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Source: Gawain Willis, Vice President of Technology, Primary Nutrition - March 2003