This study characterized seasonal changes in circulating LH and testosterone
and in semen production and quality in the Northern pintail duck. Plasma LH
and testosterone were measured in blood samples collected weekly throughout
the year from eight males exposed to natural fluctuations in day length and
temperature. Semen quality was evaluated weekly in these same males from
April–June, the months when spermatozoa were produced. Semen quality
(based on sperm concentration and normal morphology) peaked 0–2 weeks
after sperm production onset and decreased sharply before sperm production
cessation in late June. Nadir LH concentrations were measured in July and
August with peak LH observed in May and November. There were clear seasonal
patterns in circulating testosterone with July–September values being
less (P<0.05) than October–December which, in
turn, were less (P<0.05) than January–March.
Maximal circulating testosterone (P<0.05) occurred
during April–June, coincident with semen production. Weekly circulating
LH during the breeding season was directly related to testosterone
concentrations (P<0.01), but was not correlated to
any specific semen or sperm trait (P>0.05).
Testosterone concentrations throughout the breeding season were correlated
(P<0.05) to total numbers of spermatozoa produced
(volume cell concentration) and percent normal sperm morphology. In summary,
the Northern pintail experiences seasonal hormone fluctuations, with maximum
circulating testosterone coinciding with peak ejaculate quality reflected by
the production of high numbers of morphologically normal spermatozoa.
Thirty two free-ranging female white-tailed deer (Odocoileus virginianus) were anesthesized with varying Telazol and xylazine HCl combinations in Front Royal (Virginia, USA) between August 1992 and September 1992. All animals were caught in baited box traps, manually restrained, and hand injected with a combination of Telazol and xylazine administered intramuscularly. Deer received mean +/- SE dosages of 2.53+/-0.16 mg/kg Telazol and 0.69+/-0.05 mg/kg of xylazine. These dosages achieved a rapid and effective anesthetic plane for short-term procedures such as weighing, blood collection, and translocation. Eight of 32 deer (25%) required an intravenous (i.v.) supplement of ketamine HCl (100 mg) to maintain a safe plane of anesthesia. Ketamine supplementation provided an average of 11.8+/-2.0 min additional safe handling. Satisfactory reversals were achieved in all deer by administering yohimbine HCl 16 mg i.v. (dose range, 0.22 to 0.48 mg/kg) to all animals.
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