One of the main issues in poultry genetics is inbreeding. Inbreeding from imported
stock has lowered the genetic diversity from most of New Zealand’s poultry flocks
which causes other multiple problems for the farmer and their stock. Poultry with
low genetic diversity have a higher chance of genetic defects such as accelerated
growth which causes bone defects from ossification or mineralising of bone. This
causes the bones to be weak and break easily. This is one problem that affects
almost all poultry including caged, free range and backyard chickens.
A short lifespan can also be contributed to a lack of genetic diversity but this may
also be due to the profitable need for meat. Greater muscle mass is also a need for
chickens being produced for meat, and birds are selectively bred for this trait and for
quick muscle growth so the farmer sees more profit. This causes younger birds to
have extra strain on growing bones which causes the chicken’s legs to break easier.
This may cause the farmer to lose money due to the fact that all chicks hatched may
not survive to be bred from or sold for meat, or be in well enough shape for the
farmer to receive top dollar for their flock due to things like broken bones.
Selective breeding is supposed to benefit the farmer and the stock by producing a
higher yielding flock with fewer defects. This however is not always true. Selective
breeding breeds for certain traits while trying to prevent other traits from occurring.
This sometimes causes traits to be lost unknowingly, such as resistance to a specific
disease. This was started in farming to create more meat per bird and more eggs all
year round. During the process, some disease resistance has been lost and they may
now be exposed to different diseases to when they were wild, causing a need for
vaccinations.
Another problem that genetic diversity, or lack thereof, contributes to are lower
immune systems. This creates a higher need for vaccines. Vaccines are becoming
increasingly popular among poultry farmers as disease can be rife among their flocks.
Low immune systems are the cause for this. Organic farms cannot use vaccines but
their conditions are different to that of cage farms. This may be good or bad as if
disease becomes apparent in an organic farm there is a higher chance of it spreading
to most of the flock in comparison to a non-organic farm, where vaccinations may
limit or stop this spread.