Characterizing growth and carcass composition differences in pigs with varying weaning weights and postweaning...

Area of Science:

• Animal Science
• Swine Nutrition
• Physiology

Background:

• Increased litter sizes in swine production have led to more 'fallback' pigs, which are lighter at weaning.
• Limited research exists on the biological and physiological differences between fallback pigs and their normal-weight cohorts.

Purpose of the Study:

• To identify differences in biology and physiology, specifically growth and metabolism, between pigs with varying weaning weights (WW) and postweaning performance.
• To investigate the impact of weaning weight and average daily gain (ADG) on tissue accretion and carcass composition.

Main Methods:

• 120 barrows were categorized by weaning weight (lightest, median, heaviest) and further stratified by postweaning average daily gain (ADG).
• Growth and comparative slaughter experiments were conducted over 27 days.
• Data analyzed using SAS GLIMMIX procedure with fixed effects of WW category and WW(ADG).

Main Results:

• Feed intake was maximized by WW(ADG) category, but feed efficiency did not differ significantly.
• WW(ADG) category significantly affected eviscerated carcass, organ, and metabolic body weight when equalized per unit of body weight.
• Tissue nutrient concentrations, ratios, and energy content did not differ, but tissue deposition rates were maximized by WW(ADG).

Conclusions:

• Weaning weight and average daily gain significantly influence tissue accretion rates in nursery pigs.
• These factors do not appear to affect feed efficiency or overall carcass composition.
• Understanding these differences is crucial for managing swine populations with varying growth performance.