@article{borg_esbenshade_johnson_1993, title={EFFECTS OF THE PERIPUBERTAL REARING ENVIRONMENT ON ENDOCRINE AND BEHAVIORAL-RESPONSES TO ESTROUS FEMALE EXPOSURE IN THE MATURE BULL}, volume={35}, ISSN={["0168-1591"]}, DOI={10.1016/0168-1591(93)90140-K}, abstractNote={The objective of this study was to determine the impact of the peri-pubertal rearing environment upon subsequent endocrine and behavioural responses of the bulls to oestrous female exposure. Thirty Angus bulls were allotted to one of three rearing environments at 10–11 months of age: on pasture (male contact only, CON); on pasture with male contact and female contact for 2 h at 28-day intervals (female-exposed treatment, EXP); or penned individually which restricted direct physical contact with other animals (IND). Environmental conditions were maintained for 8 months after which bulls were observed during a single 30-min exposure to an oestrous female with concurrent blood sampling. Significantly elevated serum cortisol concentrations were a result of the female contact period in CON, EXP and IND bulls. Detectable increases in growth hormone were evident during oestrous female exposure in IND bulls (P<0.01). This observation was absent in CON and EXP bulls. Increased mean testosterone levels were measured subsequent to the period of female exposure in all bulls. Of the behavioural events recorded, only the elapsed time to first mounting was different between environmental rearing groups. The CON bulls were slower to initiate mounting than EXP and IND bulls (P<0.07). These results suggest that the rearing environment, at or near the time of puberty, can alter subsequent endocrine responses during mating with little or no effect on behavioural parameters during the post-pubertal period of the bull.}, number={3}, journal={APPLIED ANIMAL BEHAVIOUR SCIENCE}, author={BORG, KE and ESBENSHADE, KL and JOHNSON, BH}, year={1993}, month={Jan}, pages={245–253} }
 @article{borg_esbenshade_johnson_1991, title={Cortisol, growth hormone, and testosterone concentrations during mating behavior in the bull and boar}, volume={69}, DOI={10.2527/1991.6983230x}, abstractNote={Two experiments were conducted to evaluate peripheral concentrations of cortisol (C), growth hormone (GH), and testosterone (T) in bulls and boars during mating and to correlate mating behaviors with endocrine secretion in the presence of an estrous female. In Exp. 1, six sexually inexperienced mature bulls were bled every 15 min for 2 h before and 2 h after a 30-min exposure to a single, restrained, estrous cow; sampling occurred every 5 min during exposure. In Exp. 2, six sexually experienced boars were bled similarly before and after exposure to a sow and every 5 min during a 15-min exposure to a freely moving, estrous sow. Behavioral events recorded during exposure to a female included the following: flehmen responses (bulls only), mounts, penis extensions, intromissions, ejaculations, and time to first mount and first ejaculation. Of the six bulls, four completed at least one service (intromission + ejaculation), and three of six mounted the estrous cow eight or more times. Completion of one or more services resulted in significant elevations in serum C and GH concentrations, but not T concentrations, during the exposure period. Bulls mounting eight or more times also experienced significant elevations in C concentrations during exposure. Three of six boars completed at least one service. Servicing and mounting the sow fewer than five times were both associated with significant elevations in serum C concentrations. Serum concentrations of T were also elevated as a result of exposure to an estrous sow. Collectively, these data support the suggestion that specific events during natural mating activity can alter endocrine secretions of C and GH in bulls and C and T in boars.}, number={8}, journal={Journal of Animal Science}, author={Borg, K. E. and Esbenshade, K. L. and Johnson, B. H.}, year={1991}, pages={3230} }
 @article{borg_esbenshade_johnson_1991, title={EFFECTS OF PRETREATMENT WITH ADRENOCORTICOTROPIN ON ENDOCRINE AND BEHAVIORAL-RESPONSES OF BULLS TO SEXUAL-ACTIVITY}, volume={36}, ISSN={["1879-3231"]}, DOI={10.1016/0093-691X(91)90398-W}, abstractNote={Peripheral concentrations of cortisol, growth hormone and testosterone were determined in two experiments which examined the endocrine and behavioral responses of sexually mature Angus bulls to an estrous female (Experiment 1) and to female exposure 5 hours following an adrenocorticotropin (ACTH) injection (Experiment 2). Sexual activity of bulls in Experiment 1 significantly increased levels of cortisol when compared with concentrations before exposure to a female. Administration of ACTH in Experiment 2 consistently elevated levels of cortisol by 30-fold (P<0.01) when compared with pre-ACTH concentrations. This heightened level of cortisol persisted throughout the period of exposure to an estrous cow, although a gradual decline in cortisol concentrations occurred over time (P<0.05). In Experiment 1, growth hormone profiles tended to increase in response to sexual activity (P<0.10), whereas in Experiment 2, growth hormone increased in response to ACTH administration (P<0.01) and to female exposure (P<0.01). Concentrations of testosterone were unaffected (P>0.10) by mating activity in Experiment 1. In Experiment 2, acute suppression (P<0.01) in testosterone concentrations 5 hours after ACTH administration coincided with the exposure period to the estrous female. Frequencies of mounting behavious (penis extension, mounting, intromission and ejaculation) exhibited by ACTH-treated bulls were significantly lower compared with the frequencies two days earlier. Exogenous ACTH administration suppressed reproductive behaviors of bulls and altered secretion of cortisol, growth hormone and testosterone. Furthermore, these data provide evidence that specific mating behaviors of the bull can be influenced by circulating steroids.}, number={4}, journal={THERIOGENOLOGY}, author={BORG, KE and ESBENSHADE, KL and JOHNSON, BH}, year={1991}, month={Oct}, pages={607–618} }