Item 1, Topic 1
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4.1.1 Maturing patterns

Live weight as a function of time increases in a sigmoidal pattern as shown in Figure 4.1. 

Figure 4.1 A sigmoidal growth pattern from birth to maturity.

Mature weight

Mature weight is defined as the live weight an animal attains when it is in equilibrium with its environment.  Therefore mature weight is a relative concept that can be influenced by environmental constraints such as nutrition, temperature, activity, and disease.


Maturing patterns for body tissues

Maturing patterns of tissues can be viewed in a graphical form (see Figure 4.2) by assessing the rate at which carcase tissues mature relative to the rate at which body weight matures.  The increments in fat weight relative to body weight increase from birth to maturity.  Therefore fat is said to have a high growth impetus, or be late maturing relative to body weight.  Bone has a low growth impetus, or is said to be early maturing, because the increments in bone weight decrease from birth to maturity.  Muscle has an average growth impetus, or is average maturing, as the increments in muscle weight are similar to the increments in body weight as the animal matures. Therefore the proportion of muscle in the body remains relatively constant, while the proportion of bone decreases and the proportion of fat increases as the animal grows from birth to maturity. 

Figure 4.2 The rate at which body tissues develop to their mature weight relative to the rate at which live weight develops to its mature weight (Butterfield et al. 1983).