B. C. Wentworth

Physiological and behavioral effects of coniferyl benzoate on avian reproduction

Various plant secondary metabolites related to cinnamic acid are of interest because of their repellency to birds and their occurrence in ecologically important food items. Coniferyl benzoate (CB), a phenylpropanoid ester that occurs in quaking aspen (Populus tremuloides) is of particular ecological interest because of its effect on ruffed grouse (Bonasa umbellus) feeding behavior and its possible influence on the population dynamics of this bird. During detoxification processes, CB and other analogous compounds are metabolized into by-products, such as ferulic acid (FA), that can cause anti-reproductive effects. We tested whether consumption of CB produces antire-productive effects similar to FA using male and female Japanese quail (Coturnix coturnix) as avian models for ruffed grouse. The parameters we investigated included: the production, morphology, and development of eggs; reproductive characteristics influenced by estrogen; serum prolactin levels; and male reproductive behavior. Dietary CB did not produce antireproductive effects similar to FA at intake levels that Japanese quail and ruffed grouse would freely consume. Consumption of CB by Japanese quail significantly reduced egg production and body mass but did not affect male reproductive performance. Coniferyl benzoates effect on egg production may be explained by lower energy acquisition and retention rather than endocrine changes per se. Contrary to previous reports, it is unlikely that FA, or similar compounds act directly as estrogen mimics or antagonists. Although, CB did reduce egg production in quail, it is unlikely that it would affect egg production in wild ruffed grouse. Detoxification costs and the effects of CB on nutrient utilization may explain why ruffed grouse avoid high dietary levels of CB.

Reproductive performance of turkey hens as influenced by hormone implants 1

Large White turkey hens were implanted with silicone capsules containing either cholesterol (control), progesterone, 17-beta oestradiol (E2), oestrone (E1) or a combination of progesterone and E2. Egg production and fertility were measured. Blood samples were collected weekly for measurement of progesterone by radioimmunoassay. 2. Progesterone alone caused a several-fold increase in serum progesterone concentrations initially and significantly depressed egg production. Simultaneous administration of E2 significantly decreased progesterone concentration, but did not ameliorate the decrease in egg production. 3. There were significant positive correlations between serum progesterone concentration and egg production in control birds and those receiving E2 and E1. There was no significant correlation between progesterone concentration and fertility. 4. The results indicated that, within the physiological range, higher progesterone concentrations are associated with higher egg production. However, maintenance of constant progesterone concentrations throughout the reproductive season by means of implants was not achieved. Implants of E1 and E2 did not affect fecundity.