Submitted to: Physiology and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2001
Publication Date: 5/1/2001
Citation: Rhind, S.M., McMillen, S.R., Pekas, J.C., Duff, E. 2001. The role of cholecystokinin in the expression of seasonal variation in the feed intake and eating pattern of red deer (Cervus elaphus). Physiology and Behavior. 73:211-216.
Interpretive Summary: The role of the peptide hormone, cholecystokinin (CCK) on seasonal variation in feed intake and feeding activity in castrated male red deer (Cervus elaphus) was investigated. Five deer were actively immunized against CCK and five were injected with a vehicle solution at 2-month intervals for about 1 year. There were no effects of immunization on mean daily feed intake. The deer immunized against CCK had higher rates of fee ingestion during October to May, but lower rates of ingestion during June to September. It is concluded that CCK has a role in seasonal variation in the rate of feed ingestion. Growth hormone, thyroxine, triiodothyronine, insulin-like growth factor-1 or prolactin do not appear to be involved in the response.
Technical Abstract: The role of cholecystokinin (CCK) in the expression of seasonal variation in feed intake and feeding activity in ruminants was investigated by active immunization of castrated male red deer (Cervus elaphus). In April, animals of two groups (5 animals per group) were immunized against either CCK or vehicle solution only and booster injections were administered at 2- -month intervals for the following year. Measurements were conducted for a period of more than a year from July. There were no effects of immunization on mean daily food intake. However, there was a significant interaction between immunization and month (season), with respect to rate of feed ingestion during meals, with animals immunized against CCK exhibiting higher mean rates of ingestion during October to May but lower mean rates during June to September. It is concluded that systemic CCK has a role in the expression of seasonal variation in the rate of feed ingestion during meals in ruminants and that this in turn may affect the pattern of seasonal change in daily feed intake. Since there was no evidence of differences with treatment in profiles of insulin, growth hormone (GH), thyroxine (T**4), triiodothyronine (T**3), insulin-like growth factor-1 (IGF-1) or prolactin, it is unlikely that this effect is expressed through changes in the profiles of these hormones.