William Muir is the former director of the High Definition Genomics Center at Purdue University and still sits on the advisory board. Among his vast research, he has studied genetics and its relationship to animal well-being.
Q What occurred in the poultry industry that necessitated studying group vs. individual selection?
A Two problems needed to be addressed. The first is common to most species: competition to maintain pecking order reduces productivity and feed efficiency. The second involved beak-trimming concerns. Birds need to have their beaks trimmed to prevent them from injuring and killing each other due to pecking. However, beak trimming raises animal well-being concerns because the process is painful, and evidence suggests the pain lasts for several weeks.
Similar problems occur in swine due to tail biting. Pigs expend energy to maintain a pecking order. Tails are docked to reduced injury and infection caused by biting. However there are animal well-being concerns with tail docking.
Q What can the pork industry learn from the poultry industry's experience?
A Group selection was highly effective in reducing undesirable behaviors, such a pecking, in a relatively short time. (In this research the mortality rate dropped from 80 percent down to 8 percent.) It also had beneficial side effects of increasing the bird's stress resistance and improved feed efficiency by about 10 percent. According to Allan Schinckel, Purdue University animal scientist, a 10 percent increase in feed conversion for the swine industry would result in about 100 percent increase in profits.
Q What are the dangers of individual selection, in terms of animal well-being?
A Individual selection only selects for direct performance of the individual and ignores productivity of the pen. Poultry's results have shown that selection based on individual performance can reduce group performance – forward selection results in negative progress. The backward progress is mainly a result of increased competition and mortality, which is a major animal well-being concern for the pork industry.
Q What are the risks and rewards of group selection?
A With group selection animals are housed in a pen as a family group (full or half siblings). Several of these pens are established with different families. Selection is then among pens (families) based on the pen's total performance.
There are two downsides to group selection: inbreeding and selection intensity. Because the entire family group is selected, the rate of inbreeding increases rapidly in a small operation. Secondly, because the number of pens is an order of magnitude smaller than the number of animals, the selection intensity is less.
On the upside, the selection intensity results in much greater genetic gain in total performance than individual selection. For example, strong individual selection can take a population in the wrong direction, or if it's headed in the correct direction, it occurs at a much slower rate because of the genetic correlation with competition. Think of genetic progress as due to two traits: 1) direct gain (direct effects) and 2) indirect gain (associative or competitive effects), which are positively correlated.
With individual selection it is almost impossible to break the correlation because without direct behavioral observation it is not possible to get a handle on associative effects. The problem with direct-behavior observation is determining what to measure, how to measure it and at what cost. The nice thing about group selection is it accomplishes the same thing but without the additional costs.
Q Are there extra space requirement costs for group selection vs. individual
A Not if animals are already reared in cages or pens of small group sizes (six to 32 animals) for which a family group can be produced of the same age.
In a pork operation it could be implemented by changing how animals are housed (family groups vs. random groups). The problem is getting enough family members of the same age into the same pen.
Q What advice do you have for pork producers?
A The work of Schinckel and Spurlock of Purdue University shows that animal competition can cost pork producers up to 25 percent in lost growth. This selection technology has the power to overcome these problems and improve animal well-being at the same time.