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Fertility Testing May Aid Poultry Industry
MISSISSIPPI STATE -- A test that predicts a rooster's fertility may one day dramatically impact the poultry industry.
Mississippi's poultry holds the state's top agriculture spot, with a current farm gate value of about $1.4 billion. Research in this field can propel the industry even higher.
Dr. Chris McDaniel, poultry scientist with the Mississippi Agricultural and Forestry Experiment Station, has applied a simple fertility test to the poultry industry. His results indicate the industry could increase egg fertility rates by 5 percent.
"If the poultry industry in Mississippi saw 5 percent more broilers hatch, the state would annually gain 45.8 million broilers at a value of $8.7 million at hatching," McDaniel said. "In the whole United States, a similar 5 percent increase in fertility would result in 460 million more broilers and $87 million more value to the industry."
Currently, the broiler breeder industry predicts male fertility based on physical appearances such as the size of the comb on a rooster's head and length of a portion of the leg. This correlation is not very accurate, and the industry currently has an egg fertility rate of 90 percent. Hen fertility is accurately predicted by egg production.
McDaniel said day-old chicks are worth between 19 and 20 cents. This cost includes feed for the parent bird, space in the incubator and labor. Not all fertilized eggs hatch.
"Every infertile egg costs just as much as a fertile egg, so an increase in fertility not only means more chickens, but less loss to the industry," McDaniel said.
Trying to find a way to more accurately determine fertility in young roosters, McDaniel adapted a sperm quality analyzer, formerly used for humans, for use with poultry.
"The instrument measures sperm concentration, viability and motility -- sperm's ability to move on its own -- and gives a sperm motility index, or SMI," McDaniel said. "We know these measurements are closely related to fertility."
McDaniel's research had three steps. He first had to prove in the laboratory that sperm concentrations, viability and motility numbers influenced the SMI for chickens. With this proven, McDaniel then moved to field tests.
"I had to show that a high sperm motility index resulted in high numbers of fertilized eggs," McDaniel said.
To do this, he collected semen samples, measured sperm concentrations, viability and the sperm motility index, and then inseminated hens with the same samples. These results proved that the SMI accurately predicts fertility.
The third step involved McDaniel grouping roosters based on their SMI rating at 27 weeks old. Hens were artificially inseminated once a week for eight weeks with semen from roosters in these SMI rankings.
"We learned that semen from males found at a young age to have the highest SMI fertilized 98 percent of the eggs laid," McDaniel said. "The industry-wide average is about 90 percent fertility, so that 8 percent is a big increase."
In the groupings, only about 10 percent of the roosters ranked highest in fertility, but the top 78 percent had a 94 percent fertility rate, and the upper 53 percent had 96 percent fertility. Another important finding was that roosters kept their fertility ranking as they aged, so the SMI test need only be conducted once in a rooster's life.
A final step will determine actual fertility in natural mating situations for roosters with high SMI ratings, McDaniel said. Once the research is complete, he plans to use the results to recommend a management change to those in the poultry industry.
"I will recommend culling a slightly larger percentage of roosters, but the birds that remain will have a much superior fertility," McDaniel said. "I propose selecting birds based on semen quality to increase the chance of fertile eggs."