Although the collared peccary (Tayassu tajacu) is found throughout the Americas, with a high potential for domestication and commercial exploitation, there are few data on the reproductive biology of this mammalian species. The aim of the present study was to investigate testis structure, spermatogenic cycle length, Sertoli cell efficiency, and spermatogenic efficiency. Twelve adult peccaries were used for biometrical, histological, and stereological analyses; 3 of these peccaries received intratesticular injections of 3 H-thymidine for the determination of the duration of spermatogenesis. Testis weight and gonadosomatic index were 23.7 6 1.8 g and 0.2% 6 0.1%, respectively. Seminiferous tubule volume density was 77.4% 6 1.7%. Leydig cells occupied 12.8% 6 1.8% of the testis parenchyma and presented a peculiar cytoarchitecture in the periphery of the seminiferous tubule lobes. The premeiotic, meiotic, and postmeiotic stage frequencies were very similar to those found for wild and domestic boars. The spermatogenic cycle and entire spermatogenic process (based on 4.5 cycles) lasted approximately 12.3 6 0.2 and 55.1 6 0.7 days, respectively. Daily sperm production per gram of testis in the collared peccary was approximately 23.4 6 2 6 10 6 , which is similar to that of domestic and wild boars. The knowledge generated in the present study could be used in reproduction and animal improvement programs and provides important information that may be used for comparative reproductive biology with previously investigated mammalian species.

The agouti (Dasyprocta leporina) and paca (Agouti paca) are among the largest extant rodent species. Although these species have considerable economic potential, there are few reports in the literature concerning male reproductive biology in sexually mature agoutis and pacas. The objectives of the present study were to perform detailed stereologic and histologic analyses of the testis and estimate spermatogenic cycle length in these 2 Neotropical rodent species as well as to compare the data with those from other well-studied rodent members of the Hystricomorpha and Myomorpha suborders. Eight adult agoutis and 6 adult pacas were used. The spermatogenic cycle in agoutis and pacas lasted 9.5 6 0.03 and 11.5 6 0.16 days, respectively, whereas the total duration of spermatogenesis for these 2 species was 42.8 6 0.16 and 51.6 6 0.7 days, respectively. Most of the parameters investigated were similar to those obtained for the other members of the Hystricomorpha suborder. As a result of the combination of high values of seminiferous tubule volume density, number of Sertoli cells per gram of testis, Sertoli cell efficiency, and a relatively short duration of spermatogenesis, the spermatogenic efficiency found in agoutis (52 6 2 6 10 6 ) and pacas (39 6 2 6 10 6 ) was particularly high when compared with that of previously investigated mammalian species. The data presented in this investigation would be useful for studies related to animal production as well as improvement and conservation programs involving these 2 large Neotropical rodent species.

O objetivo do trabalho foi estudar a biologia reprodutiva da Agouti paca criada em cativeiro. Os resultados demonstraram que, a duração média do ciclo estral foi de 32,5 + 3,7 dias e o período gestacional de 148,6 + 4,8 dias. O intervalo entre partos foi de 224,5 + 52,2 dias e o primeiro cio pós-parto foi de 25,6 + 8,8 dias. A maioria (55,6 %) das fêmeas apresentou dois partos por ano, com o nascimento de um filhote por parto, sendo 44,7 % fêmeas e 55,3 % machos. Ao nascer o peso médio das fêmeas foi de 605,9 + 87,5 g e dos machos 736,7 + 108,4 g (P < 0,05). A puberdade das fêmeas ocorreu entre o 8º e 12º mês, porém neste aspecto são necessárias investigações mais detalhadas.

Plasma concentration of progesterone and 17β-estradiol of black-rumped agouti (Dasyprocta prymnolopha) during the estrous cycle. The agouti is a game animal that have been raised in captivity for conservation and sustainability purposes. However, the management of wild animals in an intensive breeding system requires an assertive knowledge of its reproductive parameters, one of the most important features for production improvement. Besides, little information is available regarding changes in reproductive hormone profiles in agouti. The objective of this study was to evaluate the hormonal profile of progesterone and 17β-estradiol during the estrous cycle of the agouti (Dasyprocta prymnolopha). The hormones were analyzed by radioimmunoassay. Blood samples were collected without sedation twice a week. The concentrations of progesterone were as follows: proestrus 0.78+0.39ng/ml, estrus 2.83+2.34ng/ml, metestrus 1.49+1.24ng/ml, diestrus 3.71+1.48ng/ml. In the estrous phase, an increase in the progesterone level was observed during a period of 24h. The average 17 β-estradiol levels were as follows: proestrus 2 030.98+961.00pg/ml, estrus 1 910.56+650.54pg/ml, metestrus 1 724.83+767.28pg/ml, diestrus 1 939.94+725.29pg/ml. The current results suggest that the progesterone plasma concentration during the estrous cycle in the agouti has a similar increasing, stabilizing and decreasing pattern, as in domestic mammals. Agoutis have two phases of follicular development, as two periods of 17β-estradiol peaks were observed, the first one in the metestrus and the second during the proestrus. Spontaneous ovulation seems to occur after the progesterone peak, possibly indicating that this hormone is associated with the ovulatory process. A more detailed investigation is needed for better understanding of how progesterone influences ovulation. Studies on the involvement of progesterone in follicular rupture can be carried out, using steroid biosynthesis inhibitors and observing the effect of this hormone on ovarian activity of proteolytic enzymes in the follicular wall.

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RESUMO -Foram realizadas análises colpocitológicas das diferentes fases do ciclo estral em 20 fêmeas adultas de cutias (Dasyprocta prymnolopha), assim como a determinação da duração da gestação em outros seis animais. As cutias foram mantidas em regime de cativeiro, nas condições climatológicas encontradas no trópico úmido da Amazônia. Os animais apresentaram reprodução do tipo poliestral continua, portanto não foi observada estação reprodutiva. A duração média dos ciclos estrais de 30,69 ± 4,65 dias e período médio de gestação de 104,33 + 0,57 dias. Com relação ao estudo da citologia esfoliativa, notou-se que no proestro houve frequência maior de células superficiais anucleadas, intermediárias e parabasals; no estro observou-se em número elevado, as células superficiais (anucleadas e nucleadas) e ausência de leucócitos; na fase de metaestro houve aumento de células intermediárias e leucócitos; no diestro, as células parabasals foram observadas em número maior de vezes.Palavras-chave: Cutia, reprodução, cativeiro, colpocitologia Determination of Agouti (Dasyprocta prymnolopha) Reproductive Cycle by Colpocytologyc DiagnosticABSTRACT-Colpocytologycs analyses in distinct phases of oestral cycle were performed in 20 female agoutis (Dasypwcta prymnolopha), as well as, the determination of gestation's ienght in six others animals. The agoutis were raised in captive management, in climatologie conditions of Amazon humid tropic. The animals showed a polyestrus continous reproduction pattern, then no sazonality was observed. The oestral period was 30,69 ± 4,65 days and the gestation's length average was 104,33 + 0,57 days. During proestrus phase the exfoliative cytology arrangement showed high frequency of anucleated superficial, intermediate and parabasal cells, respectively; the oestrus phase had elevated rates of superficial cells (anucleated and nucleated) and absence of leukocytes; highest indices of intermediate cells and an increse of leukocytes was found in metestrus phase; in diestrus phase the predominant cells type was the parabasal.