Grow-Finish: Maximizing Growth Performance

| gender & growth performance (GP) | age & GP | genetics & GP |

Basic data to estimate growth performance:
  • Feed (Nutrient) Consumed
  • Body Tissue Gained
  • Time elapsed to market size
Growth performance is determined by:

Gender

Growth performance can be determined by gender. These 4 graphs (right) show the effect of gender on protein gain, fat gain, over-all weight gain, and feed efficiency.

Gender and Protein Gain
  • Males (red) gain protein faster than females (yellow) when fed comparable diets over the same amount of time. Notice the plateau about half-way in which males and females are not gaining additional protein with added feed intake. Where is the food going? (See next graph.)
Gender and Fat Gain
  • Females (yellow) accumulate more fat over-all than males (red). But, after a certain point, males' fat gain begins to increase dramatically compared to females' steady fat gain rate. This point corresponds to the protein gain plateau (above). Therefore, feeding males more food will not lead to better growth performance after a certain point; it will only make tham fatter.
Gender and Weight Gain
  • Males gain more weight than females at a given feed amount, but keep in mind that females accumulate proportionally more fat (graph above).
Gender and Feed Efficiency
  • The X-axis is metabolizable energy intake (a measure of feed quality), the Y-axis is feed per gain. If a pig eats less feed in order to gain a unit of weight, it is more efficient. The lower (red) line is considered more efficient.
  • Males (red) use feed more efficiently than females (yellow). So, if a mixed sex group is fed a constant diet, the males will gain faster than the females. Remember, at a critical point (Gender and Fat Gain graph) males will be accumulating mostly additional fat, and not lean protein gain.
  • Q What can a herd manager do to prevent males from becoming too fat? A

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Age

Growth performance can be determined by age.

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Genetics

Growth performance can be determined by genetics. These 4 graphs (right) show the effect of genetics on protein gain, fat gain, over-all weight gain, and feed efficiency. Swine can be categorized as slow growers and fast growers. They may be slow or fast growing breeds (boars, barrows, gilts, and sows together), or they may be slow or fast growing kinds (as in, boars are fast growing compared to sows, within the same breed.) These graphs apply in either case.

Genetics and Protein Gain
  • Fast growers (red) gain protein faster than slow growers (yellow). In addition, the fast growers' protein gain does not plateau; they keep gaining protein.
Genetics and Fat Gain
  • Slow growers (yellow) gain fat faster than fast growers (red). Remember, "slow grower" could refer to a breed which grows slowly, or to females, for example, compared to males within a breed.
Genetics and Weight Gain
  • Fast growers can reach a higher weight potential than slow growers. There is no point on the graph in which fast growers' growth plateaus, and taking into account the protein gain graph, we can assume that fast growers' weight gain is mostly in desirable lean tissue mass.
  • Another way to think about this graph is to realize that fast growers need better quality (expensive) feed in order to reach their genetic potential.
  • Q Males can be considered fast growers. What can a herd manager do to keep barrows and gilts growing at comparable rates? A
Genetics and Feed Efficiency
  • The X-axis is metabolizable energy intake and the Y-axis is feed per gain.
  • Fast growers continue to use feed more efficiently than slow growers at any feed level or quality. As fast growers are fed better quality feed (to the right of the X-axis,) they are able to gain weight on increasingly less feed. As we saw above (protein gain), that gain in lean tissue mass.

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Copyright 1997 by the University of Pennsylvania School of Veterinary Medicine
Faculty: Dr. Paul Pitcher
Student: Sandra Springer,'99


A Feed them less! (return to text)

A One strategy is to split feed the barrows and gilts. Place them in different pens by gender and feed the barrows a diet with less metabolizable energy. Another strategy is to use the fact that pigs grow more slowly when they are crowded. The barrows can be slightly crowded to increase competition for feed. Crowding will cause them to gain weight more slowly. (return to text)

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