Changes in swine body composition from birth to 145 kg

Area of Science:

• Animal Science
• Nutritional Biochemistry
• Swine Physiology

Background:

• Understanding swine body composition is crucial for optimizing feeding strategies and predicting carcass yield.
• Growth and development involve dynamic changes in the proportions of water, protein, and fat.
• Previous research has established general trends, but detailed quantitative data across a wide weight range is needed.

Purpose of the Study:

• To quantitatively evaluate chemical compositional changes in swine from birth (1.5 kg) to market weight (145 kg).
• To analyze the relationship between live weight, carcass weight, and the deposition of water, protein, and fat.
• To determine the optimal mathematical models for describing these compositional changes.

Main Methods:

• Conducted an experiment with 81 crossbred swine, sacrificing groups at specific weight intervals (1.5 kg to 145 kg).
• Determined body composition by grinding the entire body (minus digesta), separating carcass and other components, and performing chemical analysis.
• Utilized logarithmic, quadratic, linear, and semilog functions to model body composition changes relative to animal weight.

Main Results:

• Carcass weight increased linearly with live weight; other body components increased quadratically.
• Empty body fat percentage rose sharply from birth to weaning, plateaued, then increased, while water percentage declined significantly.
• Protein percentage increased initially, plateaued, and then decreased after 54 kg. Fat deposition accelerated in later growth stages.

Conclusions:

• Swine do not reach full "chemical maturity" by 145 kg, as fat-free body composition continues to change.
• Logarithmic and quadratic models best described the curvilinear increases in absolute water, protein, and fat weights.
• Sex differences in composition were observed (gilts had more water, less fat), but diminished on a fat-free basis.