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ARTICLE TAKEN FROM TEXAS A & M UNIVERSITY - OVERTON WEB SITE:
December 9, 2002
Whole Cottonseed Lowers Fallow Buck Deer
Testosterone Levels, Shortens Antlers
Writer: Robert Burns (903) 834-6191,
rd-burns@tamu.edu Source: Dr. Ron Randel (903) 834-6191,
r-randel@tamu.edu TEXAS -- Feeding whole cottonseed to both free-ranging and ranched deer is a common practice this time of year. But a recent study done by the Texas Agricultural Experiment Station finds a toxic element in whole cottonseed adversely retards antler growth, lessens body condition scores and lowers testosterone levels in male deer.
The study was done with fallow deer, a species native to the Mediterranean region of Europe and Asia Minor and grown on deer farms throughout Texas, and not with white-tailed deer, the wild species native to Texas.
"However, fallow deer are similar to white-tails in body size, antler cycles and reproductive cycles. As a result, there are good reasons to believe that gossypol could also affect white-tailed deer," said Dr. Ron Randel, Texas Agricultural Experiment Station.
Whole cottonseed contains gossypol, a toxic element that naturally occurs in cotton plants. Non- ruminants, humans for example, are particularly sensitive to gossypol. The symptoms of gossypol toxicity include labored breathing, decreased growth rates and loss of appetite.
The effects of gossypol on ruminants such as white-tailed deer and related species are not so evident, but seem focused on the animal's reproductive physiology. It has long been known, for example, that gossypol toxicity will damage a bull's sperm. Early studies have also shown that the damage comes during the formation of spermatozoa, leading to damage to the tail and membrane covering.
Armed with these facts, Dr. Randel, an internationally renowned expert on beef cattle physiology, initiated a study in 2000 to measure the effects, if any, on male fallow deer. In the study, he used deer from the deer farm facilities located at the Texas A&M University Agricultural Research and Extension Center at Overton, Texas. Twelve two-year-old bucks and twelve yearling bucks were randomly split into two groups. Six bucks of each age group were fed whole cottonseed (WCS) and six were fed a cracked corn and soybean supplement calculated to be equal in nutritional value to the cottonseed rations. Deer in all groups were provided all they would eat. They were also maintained on bermudagrass pastures with free access to salt, mineral supplements and water.
At 28-day intervals, from March through October, Randel and his research team collected blood samples, body-condition scores, right and left antler measurements, scrotum circumference and testicular measurements on the deer. When antler growth ended, and the bucks began to rub the velvet off their antlers, the team collected sperm from the deer on 14-day intervals.
Antler weight and length were both reduced in the WCS fed animals compared to the control group, those eating corn/soybean rations without WCS. Average antler length was 22 centimeters (about 8 « inches) in the WCS animals compared to 36 centimeters (about 14 inches) in the controls. At 161 grams (about 6 ounces) average antler weight in the WCS animals was approximately half that of the control at 336 grams (about 12 ounces).
A more important measurement, in terms of the health of a deer herd, was the level of testosterone, the male hormone. The blood testosterone levels of the WSC animals averaged approximately half that of the corn/soybean fed control group.
"These data indicate that either cervids (deer) are being affected negatively by the gossypol intake, or they are not capable of utilizing the increased fat in the diet provided by whole cottonseed," Randel said.
Cottonseed meal as well as whole cottonseed is used in the rations of other ruminants, including beef and dairy cattle and sheep. Because beef and dairy cattle have larger rumens, they utilize fat in the diet better than deer species, and are more likely to reap positive effects from a cottonseed diet with its higher fat content, Randel noted.
To Randel, the implications of feeding whole cottonseed are clear. He is suggesting wildlife managers and deer ranchers exercise caution when using whole cottonseed as a supplement for deer.
Randel also noted that the research project has met with some naysayers. Cottonseed is a cheap feed with lots of nutritive value. Also, it is not consumed by non-target species such as the wild boar, making it ideal for large supplemental feeding projects. These benefits outweigh the negative side effects of feeding whole cottonseed they claim.
Deer farming, the raising of deer in confinement on improved pastures, is a relatively new agricultural enterprise in the United States. Until recently, exotic deer farms were not considered agricultural operations by laws in Texas and other states. Exotic deer were considered game not livestock. During the last few years, changes in Texas and other states' laws have made exotic deer farms subject to the same laws, such as herd health laws, that govern other livestock species. The change in classification also means exotic deer farms come under agricultural-use laws and may benefit from the same tax breaks.
Today, Texas law still considers the white-tailed deer as a game species, whether it is free- ranging or raised in confinement, and the sale of its meat is prohibited.
Randel has been conducting deer farming research since 1991. Early research showed non-native deer breeds such as Axis and Fallow can adapt to existing Texas pastures. In the intervening years, research has focused on aspects of reproductive management, pasture systems, business planning and product marketing for relatively intensive operations where the main goals include venison and/or velvet antler production, as well as seed stock production. The Overton Center deer farming research facilities are currently working with two species fallow and red deer.
More detailed information on deer farming and the research done at the Overton Center can be found on the Internet at
http://overton.tamu.edu/deerfarming .
