Existe pouca informação a respeito do desenvolvimento reprodutivo das serpentes Neotropicais da família Boidae. Este trabalho descreve por meio de avaliações ultrassonográficas os ciclos reprodutivos nas estações do ano (primavera, verão, outono e inverno), de exemplares das seguintes espécies: Eunectes murinus, Boa constrictor constrictor, Corallus hortulanus e Epicrates cenchria pertencentes ao acervo do Museu Biológico do Instituto Butantan. E. murinus e B. c. constrictor apresentaram vitelogênese primária prolongada, com duração de um ano, em todas as estações. A vitelogênese secundária ocorreu na primavera e no verão em E. murinus e B. c. constrictor, em todas as estações em C. hortulanus, e no inverno e primavera em E. cenchria. Houve reabsorção folicular nas quatro espécies. Cópula foi observada no inverno em B. c. constrictor e E. cenchria, e na primavera em C. hortulanus. Eunectes murinus necessita de agregações reprodutivas e E. cenchria, de ritual de combate entre os machos para ovulação e fecundação, e posteriormente gestação. Nascimentos ocorreram no verão, em B. c. constrictor e E. cenchria, e no inverno, em C. hortulanus. Ovos atrésicos foram eliminados no parto em B. c. constrictor e C. hortulanus. Houve reabsorção uterina de ovos inférteis em C. hortulanus. O tamanho da ninhada foi maior em Boa c. constrictor do que em C. hortulanus e E. cenchria. Nos machos, houve aumento de testículo na época de cópula em B. c. constrictor e E. cenchria. A ultrassonografia demonstrou ser uma técnica de diagnóstico segura e não invasiva para estudar os ciclos reprodutivos. / There is little information about to the phases of the reproductive development of Neotropical snakes of Boidae family. This paper describes by sonographic evaluations the reproductive cycles along the seasons (spring, summer, autumn and, winter), of specimens of: Eunectes murinus, Boa constrictor constrictor, Corallus hortulanus and, Epicrates cenchria belonging to the Museu Biologico of the Instituto Butantan. E. murinusand, B. c. constrictor showed prolonged primary vitellogenesis, for one year, in all seasons. The secondary vitellogenesis occurred in the spring and, summer in E. murinus and, B. c. constrictor, in all seasons in C. hortulanus and, in winter and, spring in E. cenchria. In the four species, there were follicular resorptions. Copulation was observed in winter in B. c. constrictor and, E. cenchria and, in spring in C. hortulanus. Eunectes murinus requires breeding aggregations and E. cenchria male-male ritualized combat for ovulation and, fertilization, and, after pregnancy. The births occurred in summer in B. c. constrictor and, E. cenchria, and, in winter in C. hortulanus. Atretic eggs were eliminated in parturition in B. c. constrictor and, C. hortulanus. There was resorption of uterine infertile eggs in C. hortulanus. The litter size was higher in Boa c. constrictor than in C. hortulanus and, E. cenchria. In males, there was an increase of testis during the copulation season in B. c. constrictor and E. cenchria. The ultrasonography proved to be a safe and, non-invasive diagnostic technique for studying the reproductive cycles.

O objetivo deste estudo foi avaliar as respostas comportamentais e fisiológicas, em novilhas e vacas Nelore, submetidas à protocolo de inseminação artificial em tempo fixo (IATF) de três manejos. Foram utilizadas 426 fêmeas bovinas nulíparas, primíparas e multíparas, com 30 à 90 dias de período pós-parto. O estudo decorreu entre os meses de novembro de 2011 e março de 2012, durante a estação reprodutiva. As variáveis registradas foram: velocidade de fuga (VS) em metros por segundo (m/s) e através de escores; escore de movimentação, respiração, coices e mugidos, no brete de contenção, para determinação do escore composto de reatividade (ECR); temperatura do ar, umidade do ar e temperatura do globo negro à sombra, para cálculo do índice de temperatura de globo negro e umidade (ITGU); escore de condição corporal (ECC); temperatura retal (TR); e diagnóstico de gestação (DG). O ECC, escore de VS e ECR foram analisados por testes não paramétricos. Os dados de ITGU, VS em m/s-1, TR e DG, foram submetidos à análise de variância e teste de Tukey. Correlação de Pearson foi empregada entre VS em m/s-1 e VS por escore e a correlação de Spearman para escore de VS e ECR. As médias de ITGU foram maiores para o período da tarde (P<0,05). Não houve diferença entre os três dias de manejo para VS em m/s-1 ou em escore (P>0,05). No segundo e terceiro manejo, houve alta correlação entre VS em m/s-1 e em escore (P<0,0001). Houve aumento do ECR do primeiro para o segundo dia de manejo, com estabilização do segundo para o terceiro (P<0,05). Novilhas foram mais reativas que as vacas no dia da inseminação artificial (P<0,0001). O ITGU influenciou na reatividade, sendo que, quanto maior o ITGU, maior foi o ECR (P<0,05). Também houve correlação positiva entre escore de VS e ECR (P<0,003). Novilhas apresentaram melhor ECC que as vacas (P<0,0012). O ITGU também influenciou a TR (P<0,01). Quanto maior o ITGU maior foi a TR dos animais. Novilhas apresentaram maiores TR que as vacas (P<0,01). O ECR não teve efeito sobre a TR (P=0,5550). Não houve efeito dos lotes, categoria animal, ECC, ITGU, TR, ECR e VS em escore, sobre a taxa de concepção de vacas e novilhas. Conclui-se que a reatividade pode ser influenciada pelo manejo, idade do animal e pelo conforto térmico. Nas condições que este experimento foi realizado, a taxa de concepção não foi influenciada pela condição corporal, ITGU no momento da inseminação artificial, reatividade e nem pelo escore de velocidade de fuga. / The objective of the present study was to assess the behavioral and physiological responses in Nellore heifers and cows submited to fixed time artificial insemination (FTAI) of three handling. We used a total of 426 cows and heifers nulliparous, primiparous and multiparous, 30 to 90 days postpartum. The study occurred between the months of November 2011 and March 2012, during the breeding season. The variables recorded were: exit velocity (EV) in meters per second (m/s-1) and by scores: movements, respiratory rate, kicking and mooing in squeeze chute, to determine the reactivity score (RS), air temperature, air humidity and black globe temperature in the shade, to calculate the index of black globe temperature and humidity (BGHI), body condition score (BCS), rectal temperature (RT), and pregnancy diagnosis (PD). The BCS, EV score and RS were analyzed by nonparametric tests. Data from BGHI, EV m/s-1, RT and PD were subjected to analysis of variance and Tukey test. Pearson correlation was used between EV m/s-1 and score of EV and the Spearman correlation was used for EV and RS. The average of BGHI were higher for the afternoon (P<0.05). There was no difference between the three-day handling for EV in m/s-1 or score (P>0.05). In the second and third handling, there was a high correlation between EV in m/s-1 and score (P<0.0001). An increase of the RS from the first to the second day of handling, stabilizing the second to the third (P<0.05). Heifers were more reactive than cows on the day of artificial insemination (P<0.0001). The BGHI influence the reactivity, and the greater the BGHI, the higher the RS (P<0.05). There was also a positive correlation between EV and reactivity score (P<0.003). Heifers had better BCS cows (P<0.0012). The BGHI also influenced RT (P<0.01). The largest BGHI, causes increases in RT of the animals. Heifers had higher RT than cows (P<0.01). The RS had no effect on the RT (P=0.5550). No effect of lots, animal category, BCS, BGHI, RT, RS and EV in score on the conception rate of cows and heifers. It is concluded that the reactivity can be influenced by handling, age and the thermal comfort. Under the conditions that this experiment was conducted, the conception rate was not influenced by body condition, BGHI at the time of artificial insemination, reactivity and score of exit velocity.

O objetivo do presente estudo foi avaliar a aptidão reprodutiva de cães da raça Golden Retriever afetados pela distrofia muscular. Realizou-se avaliações andrológicas em 11 cães com idades entre 10 meses e 4 anos. Destes, 7 eram afetados pela distrofia muscular e 4 sadios, utilizados como controle. Todos foram submetidos a exame clinico, análise seminal e ultra-sonografia dos órgãos reprodutores. Analisou-se também a morfologia dos testículos e seus respectivos funículos espermáticos dos cães que foram a óbito. Detectou-se as seguintes alterações nos cães afetados pela distrofia: atrofia muscular, andar rígido, pneumonia por aspiração, fragilidade do diafragma com projeção do estomago para a cavidade torácica, megaesôfago e cardiomiopatia dilatada. Em relação aos órgãos genitais dois dos cães apresentaram criptorquidismo bilateral. Os resultados das análises seminais mostraram que os cães afetados pela distrofia possuem maior quantidade de defeitos espermáticos maiores e totais. Nas avaliações ultra-sonográficas não foram identificadas diferenças entre os cães afetados pela distrofia quando comparados com cães sadios. As análises histopatológicas evidenciaram alterações morfológicas nos testículos e músculos cremáster de cães afetados pela doença. Os testículos apresentaram degeneração testicular e o músculo cremáster retração de fibras musculares com hialinizacao dos miócitos. Conclui-se então que a distrofia muscular em cães da raça Golden Retriever pode comprometer sua aptidão reprodutiva. / The aim of the present research was to evaluate the reproductive condition of Golden Retriever dogs affected by muscular dystrophy. Breeding soundness examination was performed in 11 male dogs aged between 10 months and 4 years. Seven of this total were affected by muscular dystrophy and 4 healthy dogs that served as control. All dogs were submitted to a through physical exam, seminal evaluation and ultrasound of the reproductive tract. Testicle and spermatic cord morphology of post-mortem dogs were also examined. The following alterations were observed for the affected dogs: muscular atrophy, stiff walk, aspiration pneumonia, diaphragmatic fragility with stomach projection to the torax, megaesophagus e dilated cardiomyopathy. In relation to the genital tract, two dogs presented with bilateral cryptorchidism. Semen evaluation revealed high percentage of major and total sperm defects in affected dogs. Ultrasonographic exams were similar among healthy and affected dogs. Histophatology of the testicle and cremaster muscle revealed morphologic alterations in affected dogs represented by degeneration and muscular retraction with miocyte hyalinization, respectively. In conclusion, affected Golden Retriever dogs have their reproductive performance compromised by the muscular dystrophy.

O Lobo-Marinho-do-Sul (Arctocephalus australis), carnívoro, caniforme, membro da superfamília dos Focóides, família Otaridae, é o mais comum mamífero marinho pertencente à fauna brasileira. É freqüentemente avistado, nos meses de outono e inverno na costa do Brasil, desde o Rio de Janeiro até o Rio Grande do Sul. Ainda é discutido se algum dia este animal já possuiu colônias reprodutivas neste país. É histórica a grande pressão antrópica que esta espécie recebeu, sendo explorado pelas populações litorâneas, para aproveitamento de sua pele, óleo e carne desde a antiguidade. No Uruguai, foram por muitos séculos abatidos em números que variavam em torno de 10 mil animais por ano, com o intuito de aproveitamento de sua pele para a confecção de casacos e testículos, para confecção de elixires no Oriente. Porém, deixou de ser explorado comercialmente naquele país na década de 80 e desde então seu número vem aumentando, e por isso especula-se sobre o surgimento de novos sítios reprodutivos em ilhas pedregosas, típicas de sua preferência. É possível até que estuários como o de Cananéia no litoral sul do Estado de São Paulo - BR, possam receber esta espécie nos meses de verão, o que, de acordo com a sazonalidade de sua reprodução, ocorre nesta época. Esse novo "pólo reprodutivo" pode representar um desbravamento de novas áreas (ou mesmo retorno a antigas áreas) pela espécie. É ainda muito escassa a literatura sobre esta espécie e poucos pesquisadores brasileiros a conhecem. Este trabalho buscou através da coleta de indivíduos (cinco jovens e um adulto) em óbito recente, por causas naturais, contribuir com conhecimentos anatômicos, histológicos, ultraestruturais e imuno-histoquímicos do sistema reprodutor masculino do Arctocephalus australis de animais jovens e adultos. Os resultados demonstraram muitas vezes a singularidade da espécie estudada: expressiva queratinização da camada córnea do epitélio escrotal e forte coloração negra nesta região; diferença estrutural existente entre as túnicas albugínea do testículo e do pênis: na primeira observaram-se fibras elásticas bem distribuídas e ausência destas fibras na segunda; ausência de ampolas nos ductos deferentes; uretra pélvica pequena; bulbo do pênis ventral aos pilares penianos e posicionamento singular do seu osso peniano; glande do pênis petaliforme. Encontramos um grande grau de adaptação do sistema reprodutor do macho ao da fêmea, nas duas idades estudadas, demonstrando que a evolução foi direcionada para o ciclo reprodutivo do tipo monoéstrico-estacional, de modo a otimizar a cópula e o volume do ejaculado, garantindo a deposição do sêmem o mais próximo possível do óstio uterino externo da fêmea, e conseqüentemente uma maior taxa de concepção. / The Southern-Fur-Seal (Arctocephalus australis) Carnivora, Caniform, member of the Superfamily Focoidae, Family Otaridae, is the most common marine mammal in brazilian sees, frequently seen in the months of autumn and winter in the coast from Rio de Janeiro until Rio Grande do Sul. There are controversies if some day A. australis already possessed reproductive colonies in this country. The great antropic pressure over the species is historical, being explored by cost populations because of its skin, oil, and meat. In Uruguay, it was slaughtered for many centuries in numbers that reached 10 000 animals per year: the skin was used for the confection of coats and testis, for elixir in the East. However, since the beginning of the decade of 80, commercial exploitation stopped and its number started increasing. Therefore one speculates on the sprouting of new reproductive places in stony islands, typical of its preference, and it is possible that estuaries like Cananéia, in the south coast of the State of São Paulo - BR, started to receiving this species in the summer months, what is in accordance with the reproductive season, which occurs at this time of the year. It can represent an opening of new areas (or even a return the old areas) for the species. Literature is still very scarce on this species and few brazilian researchers know about it. For developing this work, six recent dead for natural causes individuals (five young and one adult) were collected and the reproductive tract was submitted to anatomical, histological, ultrastructural and immunohistochemistry approaches aiming to improve the knowledge about the male reproductive system of the Arctocephalus australis of two ages. Results pointed towards peculiarities of the studied species: expressive keratinization of scrotal epithelium; structural differences between the tunica albuginea in the testis and penis: only in the testis elastic fibers could be observed; no ductus deferens ampulae, small pelvic urethra; glans penis in flower shape. We found a great degree of adaptation of the reproductive system of the male to the one of the female, in the two ages studied, demonstrating that the evolutive orientation was in direction of sazonal-monoestric reproductive cycle, in order to optimize copulation and the volume of the semen, guaranteeing the deposition of the semen as next as possible to the external female uterine ostium and consequently a bigger tax of conception.

A endocrinologia ovariana de cinco fêmeas de bugio da espécie Alouatta caraya foi estudada por meio de extração e dosagem de metabólitos fecais de estrógenos e progestinas durante um período de cinco meses. Adicionalmente observou-se a presença de eritrócitos por meio de citologia vaginal em três das fêmeas estudadas. Duas fêmeas, uma em condição nutricional desfavorável e outra pré-púbere, apresentaram concentrações basais de estrógenos com mediana menor que 3,7 ng/g e de progestinas menor que 29,7 ng/g de fezes úmidas. Nas outras três fêmeas a mediana dos valores de pico de estrógenos fecais foi 711,55 ng/g e dos valores basais 130,51 ng/g de fezes úmidas. Para as progestinas fecais a mediana dos valores de pico foi 2653,54 ng/g e dos valores basais foi 149,88 ng/g de fezes úmidas. Nestes três animais as concentrações de ambos os metabólitos apresentaram uma variação cíclica e o intervalo entre picos de estrógenos fecais foi 19,6±1,9 dias (média±EPM). Estes metabólitos permaneceram elevados durante 9,1±0,9 dias. Elevações sustentadas de metabólitos fecais de progestinas acompanhadas de pico e elevações de metabólitos fecais de estrógenos foram observadas em apenas quatro períodos. Nestes casos ambos os metabólitos elevaram-se aproximadamente ao mesmo tempo e estimou-se que a ovulação tivesse ocorrido antes do início destas elevações. Os períodos de sangramento coincidiram com a queda nas concentrações de estrógenos e progestinas fecais. / The ovarian endocrinology was assessed in five female howler monkeys (Alouatta caraya) by means of estrogen and progestogen metabolites extracted from fecal samples. Measurements were conducted for a period of five months, and erythrocytes were observed by vaginal cytology, in three females. In one subadult and in one undernourished female, estrogen concentrations remained at median basal levels <3.7ng/g, and the progestogen concentrations were <29.7ng/g of wet feces for almost the entire period of the experiment. For the other three females, median fecal estrogen peak concentration was 711.55ng/g and basal concentration was 130.51ng/g of wet feces. Median fecal progestogen concentration was 2653.54ng/g and for basal concentration was 149.88 ng/g of wet feces. The three females were found with a cyclical pattern for both metabolites concentrations, with fecal estrogen peak intervals of 19.6±1.9 (mean±SEM) days and the estrogen metabolites remained elevated for 9.1±0.9 days. Fecal progestogen showed sustained elevations concurrently with fecal estrogen increase only in four periods and it was presumed that ovulation had occurred before the onset of those elevations. Bleeding periods occurred with the falling of both steroid metabolites.

Esta tese está fundamentada em dois experimentos que visam colaborar na elucidação dos efeitos das afecções de casco sobre o desempenho reprodutivo de vacas leiteiras no Brasil. No experimento 1, um total de 57 vacas Holandesas no início da lactação foi utilizado para avaliar os efeitos das afecções de casco sobre o comportamento no estro. Os animais foram classificados de acordo com o escore dos cascos e o escore da locomoção, identificando-se assim animais com os cascos sadios e animais que apresentam lesões nos cascos. Todos os animais foram sincronizados com prostaglandina (Cloprostenol sódico). O comportamento destas vacas durante o estro foi monitorado por um aparelho de radiotelemetria (HeatWatchâ). Os dados relativos ao casco (variáveis independentes) foram associados com os seguintes dados relativos ao estro: número de montas, soma da duração das montas, duração média das montas, intensidade das montas e duração do estro (variáveis dependentes). Os resultados evidenciaram significância estatística apenas na relação funcional entre a variável dependente Duração do estro e a variável independente Escore de locomoção (P=0,0237; R²=0,0921). Quando foram considerados dois grupos, em função da presença do acometimento do casco, foi possível, utilizando a análise de variância, demonstrar diferença significativa com as variáveis Número de montas (P=0,0363); Soma da duração das montas (P=0,0280) e Duração do estro (P=0,0071). No experimento 2, 1447 vacas Holandesas foram utilizadas para avaliar a associação entre a incidência de claudicação e o desempenho reprodutivo. As vacas foram monitoradas desde o parto até a concepção, avaliando-se a relação entre a incidência de claudicação e os índices reprodutivos, compreendendo: intervalo do parto ao primeiro cio, ao primeiro serviço e à concepção; percentual de vacas com e sem claudicação que conceberam no primeiro serviço; número de doses por concepção e percentual de vacas com e sem claudicação vazias com mais de 210 dias de lactação. Os resultados demonstraram que no intervalo do parto ao primeiro cio houve diferença significativa (P=0,0021) de 16 dias; (P=0,0150) de 21 dias; (P=0,0027) de 26 dias e (P=0,0279) de 29 dias na data do cio quando a claudicação ocorreu no segundo mês, no terceiro mês, no quarto mês e no sexto mês da lactação, respectivamente. No intervalo do parto ao primeiro serviço houve diferença significativa (P=0,0159) de 13 dias; (P=0,0021) de 15 dias e (P=0,0044) de 17 dias na data do primeiro serviço quando a claudicação ocorreu no segundo mês, no terceiro mês e no quarto mês da lactação, respectivamente. No intervalo do parto à concepção e no número de doses por concepção não houve diferença significativa (P>0,05) entre os animais que apresentaram e que não apresentaram claudicação. Do total de 1447 vacas, 21,9% conceberam no primeiro serviço, sendo que 17% apresentaram claudicação e 82,6% não apresentaram; e 26% do total de vacas permaneceram vazias por mais de 210 dias em lactação, sendo que 68% apresentaram claudicação e 31,9% não apresentaram / This study is based in two experiments which aim to evaluate the effects of lameness on the reproductive performance of dairy cows in Brazil. In experiment 1,57 Holsteins cows in the beginning of the lactation were divided according to the hoof and locomotion score, respectively, and the incidence of lameness or not (healthy cows). All cows did receive were syncronized by prostaglandine (cloprostenol sódico) and its behavior during the estrus was monitored by a radiotelemetria device (HeatWatchâ). Following to this, it was possible to monitor the possible association of the lameness and the following data to the estrus: number of mounts, total duration of the mounts, duration average of the mounts, intensity of the mounts and the duration of the estrus. The results were statistically significant between the dependent variable estrus duration and the independent variable locomotion score (P=0,0237; R²=0,0921). While considering two groups, due to lameness, it was possible via the variance analysis to show the significant difference with the variable number of mountains (P=0,0363); sum of mountain duration (P=0,0280) and estro duration (P=0,0071). In experiment 2, 1447 Holsteins cows from 5 different farms were monitored from the calving date till the conception, where it was evaluated the relationship between the lameness incidence and the reproductive records, understanding: calving interval till first heat, first service and until conception; percentage of cows with and without lameness that were pregnant in the first service; number of dosis per conception and percentage of open cows over 210 days in milk with and without lameness. The results demonstrated that from the calving date till the first heat a significant difference of 16 days more (P=0,0021), 21 days more (P=0,0150), 26 days more (P=0,0027) and 29 days more (P=0,0027) when the lameness did happen in the second, third, fourth and sixth month of lactation, respectively. About the interval from the calving until the first insemination, a significant difference occurred in 13 days more (P=0,0159), 15 days more (P=0,0021) and 17 days more (P=0,0044) when the lameness did happen in the second, third and fourth months, respectively. In relation to the interval from calving to conception and the number of dose per conception, it was not found significant difference (P>0,05) between the animals with and without lameness. >From the total 1447 cows, 21,9% did get pregnant in the first service and from this animals, 17% did have lameness and 82,6% did not. Also, 26% of the total cows were open for more than 210 days in milk, and from this 68% did have lameness and 31,9% did not have lameness

A expressão do gene Kiss1 é essencial para o controle neuroendócrino da reprodução, pois esses neurônios regulam a atividade dos neurônios que secretam o hormônio liberador de gonadotrofinas, e portanto, o ciclo ovulatório. Em roedores sazonais, o aumento da síntese de melatonina durante o inverno é responsável pela inibição das funções reprodutivas, fato que é acompanhado pela diminuição da expressão desse gene. Devido à importância dos neurônios Kiss1 no desenvolvimento do sistema reprodutivo, o presente estudo investigou a participação da melatonina na regulação da expressão do gene Kiss1 e sua influência na reprodução, em um modelo animal não sazonal. Concluimos que condições de dias curtos (que possivelmente aumentam o período de circulação de melatonina) alteram parâmetros de amadurecimento sexual em fêmeas e, assim como o tratamento com melatonina, afetam o tamanho das gônadas de camundongos machos, mas que esses efeitos não alteram o número de neurônios que expressam o gene Kiss1 e não são suficientes para inibir a reprodução das fêmeas. / The expression of Kiss 1 gene is essential for the neuroendocrine control of reproduction, as these neurons regulate the activity of neurons that secrete gonadotropin-releasing hormone, and therefore the ovulatory cycle. In seasonal rodents, the increase in melatonin synthesis during winter is responsible for the inhibition of reproductive functions, a fact that is accompanied by decreased expression of this gene. Because of the importance of Kiss1 neurons in the development of the reproductive system, the present study investigated the involvement of melatonin in the regulation of expression of Kiss1 gene and its influence on reproduction in a non-seasonal animal. We conclude that short-day conditions (which possibly increase the period of melatonin circulation) alter sexual maturation parameters in females, and as well as melatonin treatment, affect the size of the gonads of male mice, but these effects do not change the number neurons expressing the Kiss1 gene and are not sufficient to inhibit the reproduction of female mice.

No description available.

No description available.

Four trials were conducted to investigate factors controlling the seasonal onset of reproductive activity in red deer hinds. Firstly (Chapter 4), the role of photorefractoriness to long daily photoperiods in the initiation of the seasonal reproductive activity in breeding red deer hinds was examined. Red deer hinds (n=10) were prematurely exposed to a long daily photoperiod of 15.3 h from 22 July to 8 November 1986 i.e. winter-spring (EPW), or maintained under natural photoperiods (NP). Six hinds experienced the natural changes in daily photoperiod until mid-summer but were exposed to a 15.5 h of light each day from 30 January to 30 April 1987, i.e. summer-autumn (EPS), whilst hinds in the other groups experienced naturally decreasing daily photoperiods. On 5 occasions (July 1986, January, February, March and April 1987), blood samples were collected from 4 NP and 4 EPW hinds every 20 minutes for 4 h to monitor secretion of luteinising hormone and half hourly for another 4 h following an i.v. injection of 2 µg GnRH to measure pituitary responsiveness. In January, March and April 1987 EPS hinds were also intensively sampled for 4 h. Plasma progesterone concentrations and mean date of calving indicated that the onset of breeding activity was not affected by light treatment in the EPW hinds but was delayed by 3 weeks in the EPS hinds. In contrast, supplementary lighting caused a premature elevation of plasma prolactin concentrations and advanced pelage moulting in EPW hinds only. Plasma LH secretion patterns indicated that LH pulse frequency and mean LH concentrations were greater during the breeding season than during pregnancy or, seasonal or postpartum, anoestrus. The reduction in LH secretion was partially explained by a diminished pituitary responsiveness to GnRH. Daily plasma melatonin secretion patterns indicated that the duration of the nocturnal increase in melatonin concentrations was responsive to changes in photoperiod and provided a suitable endocrine signal for measuring day length. The results suggest that, unlike the sheep and prepubertal red deer hind, the onset of seasonal breeding activity in breeding red deer hinds is not affected by long daily photoperiods in spring but is delayed if the autumnal decrease in daily photoperiod is delayed. Therefore neither the development of photorefractoriness nor the spring increase in daily photoperiods initiated the transition from seasonal anoestrus to reproductive activity in the breeding hind. However, long daily photoperiods may have entrained the annual cycle of pelage shedding and prolactin secretion. It is possible that the neuroendocrine pathway by which photoperiodic signals entrain the seasonal cycle of reproduction is separate from those which regulate other seasonal events in the breeding red deer hind. Secondly (Chapter 5), in a study of seasonality of reproduction, 4 pubertal hinds were monitored for live weight and plasma LH and progesterone concentrations from December 1987 to October 1988 (i.e. 12-22 months of age). In addition the pattern of LH secretion was also studied in 4 ovariectomised pubertal hinds implanted s.c. with controlled release implants containing 12 mg oestradiol-17β between 4 March and 25 May and between 15 June and 19 September, 1988. On several occasions (15 December, 29 February, 15 March, 24 April, 14 June, 29 June, 18 September (all hinds) and 3 October (ovariectomised hinds only) blood samples were collected every 20 minutes for 4 h to monitor secretion of luteinising hormone and following an i.v. injection of 2 µg GnRH to measure pituitary responsiveness. Plasma progesterone profiles indicated that 4-6 ovarian cycles, lasting about 19 d each, occurred in each intact hind. Regular ovarian cycles commenced in late April (26 April ± 3.4 d, mean ± s.e.m.) and ceased 3 months later in July (21 July ± 7.2 d). The number of LH pulses in the intact hinds was higher in June (1-2 pulses/4 h) than in the non-breeding season (< 1 pulse/4 h) probably due to a seasonal increase in GnRH secretion. It appears that the seasonal increase in LH pulsatility and onset of reproductive activity in the entire hinds were temporally related to a reduction in the sensitivity of LH secretion to the negative feedback effects of oestradiol in ovariectomised pubertal hinds. In the third trial (Chapter 6), 20 male and 20 female red deer calves were immunised at birth against a melatonin conjugate or injected with adjuvant only (controls). Booster injections were given on 5 occasions over the next 2 years. Stags which produced significant melatonin binding activity in response to immunisation, were heavier than the controls between 7 and 11 months of age and at 16, 20, 30 and 34 months of age. A similar but smaller effect on live weight was seen in the immunised hinds. Immunisation against melatonin did not affect the calving date of the hinds or antler development and time of casting of antlers in the stags. These results indicated that disruption of the photoperiodic signal by immunisation against melatonin may have prevented the entrainment of annual rhythms in feed intake and growth but without affecting the seasonal cycles in antler growth and ovarian activity. Finally in a series of 3 trials (Chapter 7), anoestrous red deer hinds were induced to ovulate with the GnRH analogue, buserelin. Hinds were pre-treated with intravaginal devices containing 0.6 g progesterone (CIDR-Type S) for 14 days prior to CIDR withdrawal on 4 March. In Year 1, 15 hinds were treated with 1 CIDR each and 8 hinds were injected i.m. with 4 µg buserelin (a GnRH analogue) at CIDR removal followed by 2nd injection of 10 µg 48 h later. In Year 2, 16 hinds were treated with 2 CIDRs each and 8 hinds were injected Lm. with 4, 3, 2, 2 and 10 µg buserelin at -48, -24, 0, 24 and 48 h respectively from CIDR withdrawal. In Year 3, 15 hinds were treated with 2 CIDRs and 11 hinds (Groups Band BO) injected with buserelin identical to the protocol in Year 2. At CIDR withdrawal 6 of these buserelin treated hinds (Group BO) and 4 other progesterone-primed hinds (Group 0) were injected with 500 µg oestradiol benzoate. In addition, during the breeding season, 4 hinds (Group C) were treated with double CIDRs only for 14 d from 1 April. When oestrous behaviour and the pattern of plasma LH secretion were monitored in Year 3, oestrous behaviour was less noticeable and delayed in Group B hinds and peak LH levels were lower and increased later relative to Group 0, BO and C hinds. Two weeks after CIDR withdrawal, 6 buserelin-treated hinds in both Year 1 and Year 2, and 3/5 B, 2/4 0, 3/6 BO and 4/4 C group hinds in Year 3 had a single corpus luteum present. Plasma progesterone concentrations were elevated for about 12 d in most hinds with a corpus luteum in Year 2 and in most B, BO and C Group hinds in Year 3. However, progesterone secretion was low in several Year 1 and all Group 0 hinds in Year 3 indicating that the induced corpora lutea in these hinds were functionally subnormal. There was no evidence that any of the buserelin-induced ovulations resulted in pregnancy, probably because the induced ovulations were not accompanied by normal hormonal and behavioural patterns. The experiments described in this thesis have contributed to our understanding of the regulation of seasonal breeding in red deer hinds. This knowledge may eventually enable reproductive activity to be effectively manipulated, thereby improving the efficiency of deer production systems.