Olfactory Enrichment in California Sea Lions (Zalophus californianus): An Effective Tool for Captive Welfare?

In the wild, California sea lions (Zalophus californianus) are exposed to a wide variety of sensory information, which cannot be replicated in captive environments. Therefore, unique procedures are necessary for maintaining physiological and psychological health in nonhuman animals in captivity. The effects of introducing natural scents to captive enclosures have been investigated in a variety of species, yet they have not been examined in marine mammals. This project explored the behavioral effect of scent added to the environment, with the goal of improving the welfare of sea lions in captivity. Two scent types were introduced: (a) natural scents, found in their native environment, and (b) non-natural scents, not found in their native environment. This study examined not only scent enrichment but also the possible evolutionary underpinnings of pinniped olfaction. Scent enrichment was found to significantly impact sea lion behavior as demonstrated by a reduction in pattern swimming, an increase in habitat utilization, and a reduction in stereotypical behavior. However, there were no differences in behavior between natural and non-natural scent conditions.     

Comparison of luteolytic effectiveness of several prostaglandin analogs in heifers and relative binding affinity for bovine luteal prostaglandin binding sites

The relative binding affinities for both the prostaglandin (PG)E₁ and PGF_2α specific bovine luteal binding sites were determined for five PGE and fourteen PGF derivatives and analogs. Relative binding affinity was determined using membranes prepared from bovine corpora luteal (CL) obtained from the slaughterhouse. The parent structure of the analog was a dominant feature in determining the affinity for the respective PG binding site. Luteolysis was determined in cattle following intramuscular injection of various doses of prostaglandin once between days 6 and 14 after estrus and measuring CL regression by ovarian palpation per rectum, interval between injection and return to estrus and duration of the subsequent estrous cycle. A dose which was luteolytic was established for each of eight PGF-type compounds, and a dose which was not luteolytic was also established. There appeared to be limited association between the relative affinity for the PGF_2α specific site and the estimated luteolytic dose range of these PGF analogs when tested in cattle. Differences in luteolytic potency for the compounds tested could not be explained by differences in binding affinity. Differences in metabolism and absorption may also be important in the determination of potency.     

Olfactory memory: the long and short of it

It has been proposed that memory for odors does not have a short-term (or working) memory system. The distinction between short- and long- term memory in other sensory modalities has been generally supported by three main lines of evidence: capacity differences between the proposed systems, evidence of differential coding, and differential memory losses in neuropsychological patients. The present paper examines these issues in an effort to establish a similar distinction for the memory of olfactory stimuli. Each of these lines of evidence is examined in relation to the literature on olfactory memory. Based on this examination, it seems that there is at least preliminary support from each of these lines of evidence to advocate a distinction between a long- and short-term memory for olfactory stimuli. Emphasis is placed upon the qualitative similarity of olfactory memory to other memory systems. This similarity is further highlighted through an examination of the literature pertinent to serial position effects in memory for olfactory stimuli.