Modern industry requires cost effective systems and efficient animals, focusing selection programs on reproductive traits, feed efficiency and lean growth.

Dr. Neil Shantz put forward some provoking questions during a recent presentation at the 2006 Banff Pork Seminar:

• Should biological potential be encouraged without limits?
• What drives biological changes?
• What factors will best monitor the negative effects of biological change?
• Who is best positioned to create limits for biological potential?

He challenged workshop participants to assess whether the current production industry can handle the biological potential that genetic lines currently possess. If so, he asked: "what are the specific changes that will be required within production systems to meet the public's expectations regarding animal welfare, environmental awareness and food safety?"

Over the past 20 to 30 years, production units have been attempting to capture the genetic potential of their herds. In doing so, three main traits have been the focus of geneticists due to the industry economic pressures:

• litter size
• days to 100 kg body weight
• backfat at 100 kg

For each of these traits, a potential cascade of production events may result due to the biological changes that occur for each trait to be realized. For example:

1. Litter size
   1. increased pigs weaned per sow per year
   2. increased birth weight variation and preweaning mortality
   3. increased number of piglets that are artificially reared from an early age
   4. increased abnormal behaviour - such as naval sucking
   5. pressure on stocking density in farrowing crates and nurseries
   
   
2. Age at 100 kg
   1. decrease in health resistance, pig is less robust
   2. increased leg and feet problems
   3. increased finisher herd mortality
   4. increased body weight of maternal lines
   5. decreased space in existing gestation stalls and farrowing crates for larger sows
   
   
3. Backfat at 100 kg
   1. increased shoulder sores
   2. increased sow mortality
   3. decreased feed intake capacity, increased feed efficiency
   4. increased carcass quality (lower backfat/greater lean)
   5. increased nutritional requirements and costs, but increased growth efficiency and reduced costs per kg gained

With the focus on these three traits, important aspects of other traits may have been overlooked, such as mature body weight, organ capacity or disease resistance.

Shantz commented that improvement in one trait will eventually require setbacks in another trait - there is an ultimate need for balance. For example:

• growth and skeletal development
• skeletal development and muscle mass
• organ development and growth (e.g. broiler congestive heart failure)
• health risks associated with increased in-breeding
• synthetic lines narrow the gene pool over the generations

Shantz suggested three ways in which the swine industry can respond to change:

1. Accept change as it comes, increasing production system's intensity accordingly.

2. Identify specific changes in biological limits for traits that have the potential to impact production the most.

3. Combine 1. and 2. above in order to continue to enhance production, but consider the facility and management changes required to improve animal welfare while adopting greater genetic potential in the animals.

What will the future hold for the industry? Will production performance between optimum (economic) and maximum (biological limits) levels increase or decrease in future swine industry? For pork producers and the industry to successfully adopt these changes, Shantz recommends the following strategies:

• Identify current production constraints.
• Define direct relationships or actions that could result in biological change.
• Examine solutions to improve production and capture the greater genetic potential of the animals.

Source: Alberta Government - June 2006