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John F. Patience, Ruurd Zijlstra and Harold Gonyou Prairie Swine Centre Inc.
As pork markets decline, enhancing the bottom line assumes greater importance. It has been our experience that one of the most effective ways to enhance animal productivity - and thus profits - is to improve feed intake. With only a few exceptions, better feed intake means faster growth and better litters - in short, increased profitability.
The cost of poor feed intake varies among farms. Typically, a 10% reduction in feed intake will result in pigs taking about two weeks longer to reach market weight and require 15 kg additional feed. The added feed alone represents $2.85 per pig. Slower growth is harder to place a value on, but it is likely to be well in excess of $2 per pig sold. Thus a 10% reduction in feed intake robs the bottom line of something in the order of $5 per pig sold!
Surveys have shown that feed intake varies by at least 25% among commercial farms. This may under-estimate the problem, since accurate data on feed intake is not readily available on many farms. Some of the data which is available, if estimated from long-term averages or calculated on an inventory basis, fail to identify short-term deviations from this average.
Once feed intake has been identified as a problem, the next step, obviously, is to resolve it. The following may help in identifying places where feed intake falls short.
High temperatures depress feed intake as the animal seeks to minimize the generation of metabolic heat associated with the consumption and digestion of food. For example, the optimum temperature for pigs weighing more than 55 kg, housed on partial slats, and free from drafts and wetness, is 14°C (Zhang, 1994).
Mount (1975) has suggested the following adjustments to the measured temperature to determine the effective ambient temperature: straw bedding, 4°C; concrete slats, -5°C; wet floors, -5°C to -10°C. In addition, air movement of 0.2, 0.5 and 1.5 m/sec reduce the effective ambient temperature by 4°C, 7°C and 10°C respectively.
Recent research by Dr. Harold Gonyou compared 12 different feeders, including both single and multiple space across dry or wet/dry designs. He observed a range in feed intake of about 15% across all feeders; the simple choice of wet/dry feeders as opposed to dry feeders resulted in a 5% increase in feed intake.
Floor space, or lack thereof, is known to impact on feed intake. The following equations were developed by Kornegay and Notter (1984) to relate floor space per pig to voluntary feed intake. S is floor space per pig m^2.
l Grower (27 to 54 kg): ADF (kg/pig/day) = 1.542 + 0.856S - 0.494S^2
l Finisher (44 to 92 kg): ADF (kg/pig/day) = 1.619 + 1.833S - 0.837S^2
In addition, it is well understood that deficiencies of most amino acids will depress appetite, as will inadequate sodium or chloride. Excesses of some nutrients are known to be appetite suppressants as well. Clearly, a balanced diet is essential to maximizing voluntary feed intake.
The form of the diet will also affect feed intake. For example, liquid feeding systems increase feed intake, in some cases by as much as 10% to 15%.