Recent advances in treatments for resynchronization of ovulation in small ruminants: a review

Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.(AU)

Dominance, hierarchy, and reproduction in rams and goat bucks / Dominância, hierarquia e reprodução em carneiros e bodes

The reproductive results in sheep or goat flocks is consequence of multiple factors, including the interactions between males, and how these interactions modify the sexual behavior of other males. The present review summarizes information on the dominance relationships between rams or bucks, and how these relationships affect their reproductive outcomes. Dominance relationships affect the access of some males to estrous females, influencing the total distribution of sperm among the flock. The review provides information on how dominance relationships are established during the development period, and also after mixing previously unknown males. The period of relationships establishment is extremely stressful for rams and bucks, and destabilize the social relationships, affecting even sperm quality. Dominant and subordinate males display different strategies to impregnate females, but females also participate in mate choice decisions with proceptive behaviors, selecting subordinate males, favoring the maintenance of genetic diversity. Although a high proportion of ewes that lamb twins may be impregnated by different males, there is still scarce information on how these interactions affect the final distribution of paternities. Overall, although males’ interactions have important consequences on reproduction and genetic improvement, there is still the need for more knowledge on the practical consequences of social interactions.

De maneira geral, os resultados reprodutivos do rebanho são consequência de múltiplos fatores, incluindo o efeito das interações entre os machos sobre o comportamento sexual. A presente revisão resume informações sobre como as relações de dominância entre os machos afetam os resultados reprodutivos em rebanhos ovinos e caprinos. As relações de dominância modificam o acesso de machos a fêmeas no cio, e consequentemente a distribuição total de espermatozoides no rebanho. A presente revisão fornece informações sobre como as relações de dominância são estabelecidas durante o período de crescimento e após a reunião de machos previamente desconhecidos. O período em que essas relações se estabelecem é extremamente estressante para carneiros e bodes, porque além de desestabilizar as relações sociais, afeta a qualidade dos espermatozoides. Os machos dominantes e subordinados apresentam estratégias diferentes para emprenhar as fêmeas. As fêmeas também participam das decisões de escolha do parceiro com comportamentos proceptivos, selecionando machos subordinados e favorecendo a manutenção da diversidade genética. Embora uma grande proporção de ovelhas com gestação gemelar possam ter sido fecundadas por machos diferentes, ainda há poucas informações sobre como isso afeta a distribuição final das paternidades. Em conclusão, embora as interações dos machos tenham consequências importantes na reprodução e no melhoramento genético, ainda existe a necessidade da realização de mais pesquisas sobre as consequências práticas das interações sociais em pequenos ruminantes.

Bull-bull mounts in Holstein bulls: a survey of its incidence, possible causes, and consequences in Uruguayan bull' breeders

Abstract Bulls frequently display male-male mounts, with consequences in the incidence of injuries, and possibly affecting the reproductive performance of the bulls. This behavior is known as the "buller syndrome" when appears in steers, with several individuals mounting one or a few penmates. The study aimed to collect information on the incidence of bull-bull mounts, the possible associated factors, the productive consequences, and management applied by distributing a survey to Holstein bull breeders in Uruguay. A survey was applied and responded by most Holstein breeders in Uruguay (30/33). Nineteen of the 30 breeders observed mounting behavior among bulls, and 15 of them considered it as a relevant problem. The breeders that observed the behavior had a greater number of bulls than those that did not observe it (P = 0.002). All of them observed that mounts were persistently directed towards the same individual (considering a specific period, while it remained in the group). Of these, 11 (58%) considered that this stopped only when the "buller" bull was removed from the group, mentioning that the behavior was frequently redirected to another individual. The mounts between bulls are a major problem in the breeding of Holstein bulls, with important consequences on weight gain and animal health, reproductive problems such as low libido and seminal quality, and even provoking the death of animals. Although not all breeders reported the existence of the problem, those with the bigger herds did. While some management and/or environmental conditions seem to influence (higher density, regrouping, managements that involve movement of animals, and spring) the incidence of bull-bull mounts, there are no standardized managements to avoid this behavior. Considering that most breeders were interested in including practices to minimize this problem if available, it would be essential to understand better the causes and predisposing factors to decrease its negative impacts.

Bull-bull mounts in Holstein bulls: a survey of its incidence, possible causes, and consequences in Uruguayan bull breeders

Bulls frequently display male-male mounts, with consequences in the incidence of injuries, and possibly affecting the reproductive performance of the bulls. This behavior is known as the “buller syndrome” when appears in steers, with several individuals mounting one or a few penmates. The study aimed to collect information on the incidence of bull-bull mounts, the possible associated factors, the productive consequences, and management applied by distributing a survey to Holstein bull breeders in Uruguay. A survey was applied and responded by most Holstein breeders in Uruguay (30/33). Nineteen of the 30 breeders observed mounting behavior among bulls, and 15 of them considered it as a relevant problem. The breeders that observed the behavior had a greater number of bulls than those that did not observe it (P = 0.002). All of them observed that mounts were persistently directed towards the same individual (considering a specific period, while it remained in the group). Of these, 11 (58%) considered that this stopped only when the “buller” bull was removed from the group, mentioning that the behavior was frequently redirected to another individual. The mounts between bulls are a major problem in the breeding of Holstein bulls, with important consequences on weight gain and animal health, reproductive problems such as low libido and seminal quality, and even provoking the death of animals. Although not all breeders reported the existence of the problem, those with the bigger herds did. While some management and/or environmental conditions seem to influence (higher density, regrouping, managements that involve movement of animals, and spring) the incidence of bull-bull mounts, there are no standardized managements to avoid this behavior. Considering that most breeders were interested in including practices to minimize this problem if available, it would be essential to understand better the causes and predisposing factors to decrease its negative impacts.(AU)

Multiple matings modify the estrous length, the moment of ovulation, and the estradiol and LH patterns in ewes

Abstract In several species, mating reduces the estrous length and advances ovulation. The aim of this study was to determine if multiple matings reduces the estrous length and modifies the moment of ovulation, as well as the estradiol and LH patterns in ewes. The estrous cycle of Corriedale ewes was synchronized, and the onset of receptivity was monitored every 3 h with rams, avoiding mating. At the estrous onset, ewes were assigned to two experimental groups (n=10 each): 1) estrous was monitored every 3 h with a ram avoiding mating (group CON), and 2) a ram was allowed to mate and ejaculate once every 3 h (group MAT). The ovaries were scanned with transrectal ultrasonography and blood samples were collected for measuring 17β-estradiol and LH concentrations every 3 h until ovulation. Estrus was shorter in MAT than CON ewes (24.7 ± 1.5 h vs. 30.4 ± 1.5 h, respectively; P=0.02); the proportion of animals that ovulated before the end of estrus was greater in CON ewes: (9/10 vs. 3/10, P=0.009). The area under the LH curve (AUC) was greater in MAT than CON ewes (36.1 ± 3.5 ng.h-1.mL-1 vs 24.9 ± 3.5 ng.h-1.mL-1 P=0.03). However, MAT ewes had a lower 17β-estradiol AUC than CON ewes (41.0 ± 4.9 pg.h-1.mL-1 vs 59.4 ± 4.9 pg.h-1.mL-1 P=0.01). Mating reduced the estrous length, induced a greater secretion of LH but less total 17β-estradiol secreted and, additionally, ovulation occurred more frequently after the end of estrus in mated ewes.

Multiple matings modify the estrous length, the moment of ovulation, and the estradiol and LH patterns in ewes

In several species, mating reduces the estrous length and advances ovulation. The aim of this study was to determine if multiple matings reduces the estrous length and modifies the moment of ovulation, as well as the estradiol and LH patterns in ewes. The estrous cycle of Corriedale ewes was synchronized, and the onset of receptivity was monitored every 3 h with rams, avoiding mating. At the estrous onset, ewes were assigned to two experimental groups (n=10 each): 1) estrous was monitored every 3 h with a ram avoiding mating (group CON), and 2) a ram was allowed to mate and ejaculate once every 3 h (group MAT). The ovaries were scanned with transrectal ultrasonography and blood samples were collected for measuring 17β-estradiol and LH concentrations every 3 h until ovulation. Estrus was shorter in MAT than CON ewes (24.7 ± 1.5 h vs. 30.4 ± 1.5 h, respectively; P=0.02); the proportion of animals that ovulated before the end of estrus was greater in CON ewes: (9/10 vs. 3/10, P=0.009). The area under the LH curve (AUC) was greater in MAT than CON ewes (36.1 ± 3.5 ng.h-1.mL-1 vs 24.9 ± 3.5 ng.h-1.mL-1 P=0.03). However, MAT ewes had a lower 17β-estradiol AUC than CON ewes (41.0 ± 4.9 pg.h-1.mL-1 vs 59.4 ± 4.9 pg.h-1.mL-1 P=0.01). Mating reduced the estrous length, induced a greater secretion of LH but less total 17β-estradiol secreted and, additionally, ovulation occurred more frequently after the end of estrus in mated ewes.(AU)

Adult and yearling pampas deer stags (Ozotoceros bezoarticus) display mild reproductive seasonal patterns with maximum values in autumn

The pampas deer is an endangered species, from which reproductive biology little is known. We aimed to describe and compare the reproductive seasonal patterns of adult and yearling pampas deer stags throughout the year, including morphological traits, testosterone concentration, sperm morphology and cryoresistance pattern changes. Six adult (AS) and five yearling (YS) stags were captured with anesthetic darts once in winter, spring, summer and autumn to study morphological variables, serum testosterone and semen. Adult males were heavier, their neck girth tended to be greater and their testosterone concentration was higher than in YS. Animals were heavier in summer and autumn. Neck girth and testosterone concentration were greater in autumn. Scrotal circumference, testicular volume and gonado-somatic index varied with seasons, decreasing from winter to spring, increasing in summer and remaining in greater values in autumn. Sperm quality had maximum values from summer to winter. However, the cryoresistance ratio of motility score was greater in spring. In conclusion, in the captivity conditions, pampas deer stags seems to present a light seasonal reproductive pattern, with maximum testis size, testosterone secretion and fresh semen quality in autumn. Nevertheless, sperm cryoresistance ratio seemed to remain stable along the year. Although YS were still growing, they achieved similar semen quality than AS.

Adult and yearling pampas deer stags (Ozotoceros bezoarticus) display mild reproductive seasonal patterns with maximum values in autumn

The pampas deer is an endangered species, from which reproductive biology little is known. We aimed to describe and compare the reproductive seasonal patterns of adult and yearling pampas deer stags throughout the year, including morphological traits, testosterone concentration, sperm morphology and cryoresistance pattern changes. Six adult (AS) and five yearling (YS) stags were captured with anesthetic darts once in winter, spring, summer and autumn to study morphological variables, serum testosterone and semen. Adult males were heavier, their neck girth tended to be greater and their testosterone concentration was higher than in YS. Animals were heavier in summer and autumn. Neck girth and testosterone concentration were greater in autumn. Scrotal circumference, testicular volume and gonado-somatic index varied with seasons, decreasing from winter to spring, increasing in summer and remaining in greater values in autumn. Sperm quality had maximum values from summer to winter. However, the cryoresistance ratio of motility score was greater in spring. In conclusion, in the captivity conditions, pampas deer stags seems to present a light seasonal reproductive pattern, with maximum testis size, testosterone secretion and fresh semen quality in autumn. Nevertheless, sperm cryoresistance ratio seemed to remain stable along the year. Although YS were still growing, they achieved similar semen quality than AS.(AU)

Biostimulation in primiparous postpartum acyclic early weaned beef cows: introducing the bulls at weaning advances cyclic rebreeding

Weaning and biostimulation promote an early cyclic postpartum rebreeding. Although the signals and mechanisms by which weaning and biostimulation differ, both end stimulating LH secretion. The aim of the experiment was to determine if weaning and biostimulation have additive effects advancing the postpartum rebreeding in primiparous postpartum anoestrous cows. The experiment was performed during late spring – early summer with 51 primiparous Hereford cows. Six weeks after parturition calves were weaned, and cows were managed in two experimental groups: WB (n = 22) and WDB (n = 29). Bulls were joined with WB cows at weaning, but joining was delayed one week in WDB cows. The presence of corpora lutea in the ovaries was recorded weekly with ultrasound, and 28 and 50 days after the end of the exposure period, pregnancy was determined by ultrasound. The percentage of cyclic cows was greater in WB than in WDB on Weeks 8 (36.4 vs 0 %), 9 68.2 vs 13.8 %), 10 (86.4 vs 27.6 %) and 11 (100.0 vs 37.9 %) (P < 0.001 in all). Cows that were weaned and biostimulated simultaneously rebred earlier than WDB cows (Week 9.1 ± 0.2 vs Week 11.0 ± 0.2; P < 0.0001). At the end of the experiment 46/51 (90.2%) of the animals were cycling. Pregnancy rate tended to be greater in WB than WDB cows 28 days after the end of the breeding period 18/22 vs 17/29, P = 0.077), but there was no difference at the end of the study (20/22 vs 24/29, ns). In conclusion, the application of weaning and biostimulation simultaneously advances postpartum rebreeding more than weaning alone in beef cows.

Biostimulation in primiparous postpartum acyclic early weaned beef cows: introducing the bulls at weaning advances cyclic rebreeding

Weaning and biostimulation promote an early cyclic postpartum rebreeding. Although the signals and mechanisms by which weaning and biostimulation differ, both end stimulating LH secretion. The aim of the experiment was to determine if weaning and biostimulation have additive effects advancing the postpartum rebreeding in primiparous postpartum anoestrous cows. The experiment was performed during late spring early summer with 51 primiparous Hereford cows. Six weeks after parturition calves were weaned, and cows were managed in two experimental groups: WB (n = 22) and WDB (n = 29). Bulls were joined with WB cows at weaning, but joining was delayed one week in WDB cows. The presence of corpora lutea in the ovaries was recorded weekly with ultrasound, and 28 and 50 days after the end of the exposure period, pregnancy was determined by ultrasound. The percentage of cyclic cows was greater in WB than in WDB on Weeks 8 (36.4 vs 0 %), 9 68.2 vs 13.8 %), 10 (86.4 vs 27.6 %) and 11 (100.0 vs 37.9 %) (P < 0.001 in all). Cows that were weaned and biostimulated simultaneously rebred earlier than WDB cows (Week 9.1 ± 0.2 vs Week 11.0 ± 0.2; P < 0.0001). At the end of the experiment 46/51 (90.2%) of the animals were cycling. Pregnancy rate tended to be greater in WB than WDB cows 28 days after the end of the breeding period 18/22 vs 17/29, P = 0.077), but there was no difference at the end of the study (20/22 vs 24/29, ns). In conclusion, the application of weaning and biostimulation simultaneously advances postpartum rebreeding more than weaning alone in beef cows.(AU)

Rearing bucks isolated from females affects negatively their sexual behavior when adults

In some domestic ruminants, contact with females is necessary for normal development of sexual behavior. The aims of this experiment were to determine if rearing bucks isolated from does affects negatively their sexual behavior when adults, and if this negative effect is overcome after four short contacts with females. Sixteen Saanen male kids were maintained during one year in two groups: kids reared in permanent direct contact with four adult goats (FEM;n = 7), and kids that remained isolated from females (ISO; n = 9). When bucks were 12 mo-old, females were removed and both groups were joined in the FEM pen. Nine months later all bucks were individually exposed four times to estrual females for 20 min every 10 days, recording courtship and mounting behaviors. Bucks that were reared with females displayed More courtship behaviors, ejaculations and total mounts(mount attempts, mounts with and without ejaculation; P < 0.0001 for all) than ISO bucks. The combined effect of number of bucks that ejaculated and the time at which they first ejaculated in the first and second tests favored FEM bucks (P < 0.03). It was concluded that the lack of contact with females during the rearing period affects negatively adult bucks sexual performance,an effect that could not be overcome after repeated exposures to estural does.(AU)

Rearing bucks isolated from females affects negatively their sexual behavior when adults

In some domestic ruminants, contact with females is necessary for normal development of sexual behavior. The aims of this experiment were to determine if rearing bucks isolated from does affects negatively their sexual behavior when adults, and if this negative effect is overcome after four short contacts with females. Sixteen Saanen male kids were maintained during one year in two groups: kids reared in permanent direct contact with four adult goats (FEM;n = 7), and kids that remained isolated from females (ISO; n = 9). When bucks were 12 mo-old, females were removed and both groups were joined in the FEM pen. Nine months later all bucks were individually exposed four times to estrual females for 20 min every 10 days, recording courtship and mounting behaviors. Bucks that were reared with females displayed More courtship behaviors, ejaculations and total mounts(mount attempts, mounts with and without ejaculation; P < 0.0001 for all) than ISO bucks. The combined effect of number of bucks that ejaculated and the time at which they first ejaculated in the first and second tests favored FEM bucks (P < 0.03). It was concluded that the lack of contact with females during the rearing period affects negatively adult bucks’ sexual performance,an effect that could not be overcome after repeated exposures to estural does.

Sincronização e indução do estro em caprinos leiteiros / Synchronization and induction of estrus in dairy goats

A estacionalidade reprodutiva em caprinos enfraquece a cadeia produtiva e torna inconstante a receitaobtida. Produtores procuram utilizar protocolos hormonais ou metodologias naturais visando obter melhoresíndices produtivos. As cabras apresentam padrão de estacionalidade distinto de acordo com a latitude que seencontram no Brasil e fatores como a nutrição, interações sociais e aspectos climáticos parecem ser componentesimportantes. Na estação reprodutiva, a sincronização do estro é obtida pelo uso de agentes luteolíticosintervalados por sete ou 11,5 dias. Na contra estação, a indução do estro sincronizado é obtida por meio dedispositivos intravaginais contendo progestágenos mantidos por seis dias em associação a diferentesgonadotropinas, aplicadas de 48 a 24 h antes da retirada do dispositivo. Hormônios indutores de ovulaçãotambém podem ser adotados. Igualmente, é importante considerar o estado fisiológico e a capacidadereprodutiva dos machos. No repouso sexual, os mesmos podem ser estimulados pelo uso da melatonina, manejodo fotoperíodo, o bioestímulo por cabras em estro e a aplicação de eCG. Dentre as estratégias naturais, destacaseo uso do efeito macho, efeito fêmea, controle artificial do fotoperíodo e a associação entre estes visando apromoção de sistemas orgânicos e sustentáveis a partir de métodos verdes, éticos e limpos.(AU)

The reproductive seasonality in goats weakens the productive chain and makes inconstant the income obtained.In this way, farmers usually apply hormonal protocols or natural techniques in order to improve productiveindexes. Goats present a distinct seasonal pattern according to the latitude found in Brazil and factors asnutrition, social interactions and climate appear to be important components. In the reproductive season, estrussynchronization is achieved by the use of luteolytic agents as prostaglandin analogs at intervals of seven or 11.5days. The induction of synchronized estrus is obtained through intravaginal devices containing natural orsynthetic progestogens for six days in association with gonadotropins applied 48 to 24 hours before deviceremoval. Ovulation-inducing hormones can also be adopted. Similarly, it is important to consider thephysiological status and reproductive capacity of males. At the nonbreeding season, bucks can be stimulated bythe use of melatonin, photoperiod management, by does in estrus and the administration of eCG. Among thenatural strategies, it is important to highlight the male and female effect, artificial control of photoperiod andtheir association, aiming to promote organic and sustainable systems applying green, ethical and clean methods.(AU)

Sincronização e indução do estro em caprinos leiteiros / Synchronization and induction of estrus in dairy goats

A estacionalidade reprodutiva em caprinos enfraquece a cadeia produtiva e torna inconstante a receitaobtida. Produtores procuram utilizar protocolos hormonais ou metodologias naturais visando obter melhoresíndices produtivos. As cabras apresentam padrão de estacionalidade distinto de acordo com a latitude que seencontram no Brasil e fatores como a nutrição, interações sociais e aspectos climáticos parecem ser componentesimportantes. Na estação reprodutiva, a sincronização do estro é obtida pelo uso de agentes luteolíticosintervalados por sete ou 11,5 dias. Na contra estação, a indução do estro sincronizado é obtida por meio dedispositivos intravaginais contendo progestágenos mantidos por seis dias em associação a diferentesgonadotropinas, aplicadas de 48 a 24 h antes da retirada do dispositivo. Hormônios indutores de ovulaçãotambém podem ser adotados. Igualmente, é importante considerar o estado fisiológico e a capacidadereprodutiva dos machos. No repouso sexual, os mesmos podem ser estimulados pelo uso da melatonina, manejodo fotoperíodo, o bioestímulo por cabras em estro e a aplicação de eCG. Dentre as estratégias naturais, destacaseo uso do efeito macho, efeito fêmea, controle artificial do fotoperíodo e a associação entre estes visando apromoção de sistemas orgânicos e sustentáveis a partir de métodos verdes, éticos e limpos.

The reproductive seasonality in goats weakens the productive chain and makes inconstant the income obtained.In this way, farmers usually apply hormonal protocols or natural techniques in order to improve productiveindexes. Goats present a distinct seasonal pattern according to the latitude found in Brazil and factors asnutrition, social interactions and climate appear to be important components. In the reproductive season, estrussynchronization is achieved by the use of luteolytic agents as prostaglandin analogs at intervals of seven or 11.5days. The induction of synchronized estrus is obtained through intravaginal devices containing natural orsynthetic progestogens for six days in association with gonadotropins applied 48 to 24 hours before deviceremoval. Ovulation-inducing hormones can also be adopted. Similarly, it is important to consider thephysiological status and reproductive capacity of males. At the nonbreeding season, bucks can be stimulated bythe use of melatonin, photoperiod management, by does in estrus and the administration of eCG. Among thenatural strategies, it is important to highlight the male and female effect, artificial control of photoperiod andtheir association, aiming to promote organic and sustainable systems applying green, ethical and clean methods.

Reproducción en los cérvidos: una revisión con énfasis en el venado de campo (Ozotoceros bezoarticus) / A review on deer reproduction, with emphasis on pampas deer (Ozotoceros bezoarticus)

La presente revisión busca mostrar la amplia variabilidad que hay en los patrones reproductivos de diversas especies de cérvidos, lo que se vincula con la diversidad de hábitats y condiciones en que han evolucionado las mismas. Se presenta información sobre los factores que determinan la estacionalidad reproductiva, y por tanto como varía esta entre diferentes especies, la ciclicidad de las hembras, y su gestación. A su vez, se incluye información sobre los patrones reproductivos del venado de campo (Ozotoceros bezoarticus), una especie en peligro de extinción que habita el cono sur de Sudamérica. El conocimiento sobre la biología reproductiva de la misma es reciente, habiéndose determinado el patrón estacional de hembras y machos, descrito la anatomía reproductiva en ambos sexos, algunos aspectos del control del desarrollo de las astas, el comportamiento reproductivo, como la presencia de hembras influye sobre la fisiología reproductiva de los machos, el establecimiento y la evolución del vínculo entre la madre y la cría, el desarrollo de técnicas de colección de semen, y las principales características del mismo.(AU)

The present review aims to show the high diversity on the reproductive patterns of different deer species, which is related to the conditions in which each species evolved. The review includes information on the different seasonal reproductive patterns and how are them determined, female cyclic activity, and gestation patterns. Moreover, there is original information on the reproductive patterns of pampas deer (Ozotoceros bezoarticus), an endangered species that inhabits the southern cone of South America. Recently, the seasonal pattern in males and females, the males and females reproductive anatomy, some main influences on antler development, main behavioral patterns, the influence of female presence on males reproductive status, the establishment of the mother-young bond, and how it evolves, the development of techniques for semen collection, and the main seminal characteristics are summarized.(AU)

Reproducción en los cérvidos: una revisión con énfasis en el venado de campo (Ozotoceros bezoarticus) / A review on deer reproduction, with emphasis on pampas deer (Ozotoceros bezoarticus)

La presente revisión busca mostrar la amplia variabilidad que hay en los patrones reproductivos de diversas especies de cérvidos, lo que se vincula con la diversidad de hábitats y condiciones en que han evolucionado las mismas. Se presenta información sobre los factores que determinan la estacionalidad reproductiva, y por tanto como varía esta entre diferentes especies, la ciclicidad de las hembras, y su gestación. A su vez, se incluye información sobre los patrones reproductivos del venado de campo (Ozotoceros bezoarticus), una especie en peligro de extinción que habita el cono sur de Sudamérica. El conocimiento sobre la biología reproductiva de la misma es reciente, habiéndose determinado el patrón estacional de hembras y machos, descrito la anatomía reproductiva en ambos sexos, algunos aspectos del control del desarrollo de las astas, el comportamiento reproductivo, como la presencia de hembras influye sobre la fisiología reproductiva de los machos, el establecimiento y la evolución del vínculo entre la madre y la cría, el desarrollo de técnicas de colección de semen, y las principales características del mismo.

The present review aims to show the high diversity on the reproductive patterns of different deer species, which is related to the conditions in which each species evolved. The review includes information on the different seasonal reproductive patterns and how are them determined, female cyclic activity, and gestation patterns. Moreover, there is original information on the reproductive patterns of pampas deer (Ozotoceros bezoarticus), an endangered species that inhabits the southern cone of South America. Recently, the seasonal pattern in males and females, the males and females’ reproductive anatomy, some main influences on antler development, main behavioral patterns, the influence of female presence on males’ reproductive status, the establishment of the mother-young bond, and how it evolves, the development of techniques for semen collection, and the main seminal characteristics are summarized.

Sincronización de celos en ovejas y cabras con dispositivos intravaginales liberadores de progestágenos: alteraciones en ambiente vaginal y su relación con la fertilidad / Estrous synchronization with intravaginal devices in sheep and goats: alterations in vaginal environment and its relation with fertility

Los dispositivos intravaginales impregnados con progesterona o progestágenos son frecuentemente utilizados para la sincronización de los celos en ovejas y cabras. Sin embargo, la fertilidad de estos tratamientos es más baja que la de una ovulación espontánea, lo que parece tener un origen multicausal. La presencia de los dispositivos en la vagina (esponjas o dispositivos de silicona) provoca cambios en el ambiente vaginal caracterizados por un incremento en el número y una alteración en la composición de la biota bacteriana además de cambios histológicos y citológicos de la pared vaginal. El crecimiento bacteriano es fundamentalmente basado en un aumento en las bacterias coliformes Gram-negativas (E. coli y Klebsiella spp.). Estas vaginitis son responsables por sí mismas de una significativa reducción en las tasas de concepción. La acumulación de productos bacterianos e inflamatorios en el entorno vaginal afecta la viabilidad espermática. Recientemente, observamos que los espermatozoides en contacto con moco vaginal de ovejas en celo sincronizado con esponjas presentan alteraciones en su funcionalidad y viabilidad. El resultado del uso de dispositivos intravaginales está condicionado no solo por la respuesta ovárica, sino también por los cambios que provoca en el ambiente vaginal normal.(AU)

Intravaginal devices impregnated with progesterone or progestagens are widely used for estrous synchronization in ewes and goats. However, due to several causes, the fertility obtained with these treatments is lower than in a spontaneous estrus. The presence of these devices in the vagina induces an increase of the vaginal biota, changes in its composition, histological and cytological alterations in the vaginal wall. The main bacterial growth is based in Gram negative coliforms (E. coli y Klebsiella spp.). An important reduction in conception rates can be achieved to vaginitis. The accumulation of bacterial and inflammatory products in the vagina affects the sperm viability. Recently we have observed that the spermatozoa functionality and viability is affected after co-incubation with vaginal mucus collected from ewes pretreated with intravaginal sponges. Overall, the results of treatments with intravaginal devices are affected by the ovarian response but also by the changes induced in the normal vaginal environment.(AU)

Sincronización de celos en ovejas y cabras con dispositivos intravaginales liberadores de progestágenos: alteraciones en ambiente vaginal y su relación con la fertilidad / Estrous synchronization with intravaginal devices in sheep and goats: alterations in vaginal environment and its’ relation with fertility

Los dispositivos intravaginales impregnados con progesterona o progestágenos son frecuentemente utilizados para la sincronización de los celos en ovejas y cabras. Sin embargo, la fertilidad de estos tratamientos es más baja que la de una ovulación espontánea, lo que parece tener un origen multicausal. La presencia de los dispositivos en la vagina (esponjas o dispositivos de silicona) provoca cambios en el ambiente vaginal caracterizados por un incremento en el número y una alteración en la composición de la biota bacteriana además de cambios histológicos y citológicos de la pared vaginal. El crecimiento bacteriano es fundamentalmente basado en un aumento en las bacterias coliformes Gram-negativas (E. coli y Klebsiella spp.). Estas vaginitis son responsables por sí mismas de una significativa reducción en las tasas de concepción. La acumulación de productos bacterianos e inflamatorios en el entorno vaginal afecta la viabilidad espermática. Recientemente, observamos que los espermatozoides en contacto con moco vaginal de ovejas en celo sincronizado con esponjas presentan alteraciones en su funcionalidad y viabilidad. El resultado del uso de dispositivos intravaginales está condicionado no solo por la respuesta ovárica, sino también por los cambios que provoca en el ambiente vaginal normal.

Intravaginal devices impregnated with progesterone or progestagens are widely used for estrous synchronization in ewes and goats. However, due to several causes, the fertility obtained with these treatments is lower than in a spontaneous estrus. The presence of these devices in the vagina induces an increase of the vaginal biota, changes in its composition, histological and cytological alterations in the vaginal wall. The main bacterial growth is based in Gram negative coliforms (E. coli y Klebsiella spp.). An important reduction in conception rates can be achieved to vaginitis. The accumulation of bacterial and inflammatory products in the vagina affects the sperm viability. Recently we have observed that the spermatozoa functionality and viability is affected after co-incubation with vaginal mucus collected from ewes pretreated with intravaginal sponges. Overall, the results of treatments with intravaginal devices are affected by the ovarian response but also by the changes induced in the normal vaginal environment.

Gross anatomy of the stomach of the pampas deer, Ozotoceros bezoarticus (Artiodactyla: Cervidae)

The macroscopic anatomy of the stomach of the adult pampas deer, Ozotoceros bezoarticus (Linnaeus, 1758), a cervid species considered to ingest high quantities of grass in its natural diet, was described. Fourteen deceased adult pampas deer of both sexes from a captive breeding station were used for this study. There were no differences in the absolute or relative size from the different compartments of the stomach in relation to gender. Compared to measurements in other ruminants, pampas deer appeared anatomically capable of feeding on a variety of diets as an 'intermediate feeder'.

Gross anatomy of the stomach of the pampas deer, Ozotoceros bezoarticus (Artiodactyla: Cervidae)

The macroscopic anatomy of the stomach of the adult pampas deer, Ozotoceros bezoarticus (Linnaeus, 1758), a cervid species considered to ingest high quantities of grass in its natural diet, was described. Fourteen deceased adult pampas deer of both sexes from a captive breeding station were used for this study. There were no differences in the absolute or relative size from the different compartments of the stomach in relation to gender. Compared to measurements in other ruminants, pampas deer appeared anatomically capable of feeding on a variety of diets as an 'intermediate feeder'.