Management of reproductive seasonality in small ruminants

The majority of the species of small ruminants are seasonal reproducers, which implies that there are changes in their reproductive physiology that determine the existence of a reproductive season, in which the females cycle and ovulate and the males present their maximum reproductive activity, and an anestrus season, in which the females do not present estrous cycles and the males decrease their level of reproductive activity. The reproductive seasonality is an evolutionary consequence of the species so that the births occur at the most favorable moment for the survival of their offspring, which in temperate climates usually occurs in the spring. In the case of rams and goats there are annual variations in the concentration of LH, FSH and testosterone, which generates changes in the characteristics of semen and sexual behavior. For example, during the reproductive season the diameter of the seminiferous tubules and the epididymis increases, the number of spermatogonia in the seminiferous tubules, and the size, weight and activity of the secondary sex glands. This determines that the males of many breeds of sheep and goats have a low capacity to breed female cycling during this period

Managing reproductive seasonality in small ruminants

Most species and breeds of small ruminants, especially sheep and goats, have seasonal reproduction, meaning that females cycle for part of the year and remain in anestrous during the remaining part, while males increase and decrease in reproductive activity in sync with females. This is regulated primarily by variations in the length of daylight. During darkness, the hormone melatonin is secreted and synchronizes physiological processes with environmental conditions. Limits are thus placed on the months of the year in which these animals can reproduce and, therefore, the availability of lambs or kids. This review briefly introduces the principal techniques used to modify the seasonal pattern in sheep and goats, and for several of these, recent technical information is included. Hormonal methods, basically involve pharmacological estrous cycle creation in a female (progesterone + gonadotropin) or placement of subcutaneous implants that release melatonin. In the male use of these implants is also effective, and recent information suggests the potential use of equine chorionic gonadotrophin (eCG) to improve reproductive performance outside the normal season. Information is presented about stimuli that alter the physiology of the animal, such as manipulating the number of hours of light or darkness that an animal is exposed to, thus, allowing reversal of the seasonal effects in both males and females. Managing the social environment of the animals can also be effective in modifying seasonality. The male effect consists of suddenly exposing previously isolated anestrous females to rams and bucks, which induces neuroendocrinal changes that can lead to the expression of estrus accompanied by ovulation. The stimulus caused by the presence of other cycling females is also effective to induce ovulation in anestrus females, especially goat does, while in the case of ewes, this occurs after close physical contact with the cycling animals. Conversely, sudden contact of rams and bucks with females in estrus induces substantial increases in the secretion of gonadotropins and androgens and, if the stimulus is sufficiently maintained, it is possible to modify the reproductive status of these males. Lastly, the advantages and disadvantages of each of these technologies is discussed

Impacto científico dos pesquisadores: contribuição vs h-index?

Durante los últimos años aumentó el uso de los índices de impacto por parte de instituciones para evaluar a las revistas científicas, la productividad de las instituciones, o a los investigadores. En el presente artículo se discute la validez del uso de estos indicadores para evaluar la trayectoria académica de los investigadores. El indicador más utilizado para evaluar a los investigadores es el índice h, el que se basa en la cantidad de artículos citados al menos una mínima cantidad de veces h. Este índice no considera la producción que está por debajo de ese valor, el impacto o aporte individual del investigador, su ubicación como autor en los artículos, los años de trabajo del mismo, el área temática, o el tiempo que requieren algunos artículos, en algunos temas, para efectivamente impactar a nivel de la comunidad científica. Se utiliza el perfil de citas de Einstein y del artículo de Watson y Crick (1953) en que se describe la doble hélice del ADN como ejemplos que muestran que el mayor impacto puede no ser inmediato y requerir años de desarrollo del área, a pesar de que su importancia fuera clave para el desarrollo de la misma. Los índices son formas de cuantificar impactos, pero el uso y abuso de los mismos, y sobre todo el uso para considerar aspectos que no son los que miden, puede llevar a conclusiones equivocadas. Si bien son parte de las herramientas disponibles para medir productividad científica, los mismos deben ser considerados en función de lo que efectivamente miden en base a los insumos y criterios en que se basan. Por tanto, es importante que los sistemas de evaluación científica los pongan en contexto al considerarlos para la evaluación del desempeño académico.In recent years, the use of impact indexes by institutions to evaluate scientific journals, the productivity of institutions, or researchers, has increased. This article discusses the validity of the use of these indicators to assess the academic trajectory of researchers. The most widely used indicator to evaluate researchers is the h-index, which is based on the number of articles cited at least a minimum number of times h. This index does not consider the production that is below that value, the impact or individual contribution of the researcher, the author’s positions in the articles, the time during which those articles were published, the subject area, or the time that some articles require in some topics to effectively impact at the level of the scientific community. Einstein's citation profile and Watson and Crick's (1953) article describing the DNA double helix are used as examples showing that the greatest impact may not be immediate and may require years of development in the scientific area, despite that its importance was key to its development. The indices are ways of quantifying impacts, but their use and abuse, and especially their use to consider aspects that are not what they measure, can lead to wrong conclusions. Although they are part of the tools available to measure scientific productivity, they must be considered based on what they measure based on the inputs and criteria on which they are based. Therefore, it is important that scientific evaluation systems put them in context when considering them for the evaluation of academic performance.Nos últimos anos, aumentou o uso de índices de impacto por instituições para avaliar periódicos científicos, a produtividade das instituições ou dos pesquisadores. Este artigo discute a validade do uso desses indicadores para avaliar a trajetória acadêmica de pesquisadores. O indicador mais utilizado para avaliar pesquisadores é o índice h, que se baseia no número de artigos citados pelo menos um número mínimo de vezes h. Este índice não considera a produção abaixo desse valor, o impacto ou contribuição individual do pesquisador, sua posição como autor nos artigos, seus anos de trabalho, a área temática ou o tempo que alguns artigos exigem, em alguns tópicos, para impactar efetivamente a nível da comunidade científica. O perfil de citações de Einstein e o artigo de Watson e Crick (1953) descrevendo a dupla hélice do DNA são usados ​​como exemplos mostrando que o maior impacto pode não ser imediato e pode exigir anos de desenvolvimento da área, apesar de sua importância ter sido fundamental para seu desenvolvimento. Os índices são formas de quantificar impactos, mas seu uso e abuso, e principalmente para considerar aspectos que não são o que eles medem, pode levar a conclusões equivocadas. Embora façam parte das ferramentas disponíveis para medir a produtividade científica, devem ser consideradas com base no que realmente medem com base nos insumos e critérios nos quais se baseiam. Portanto, é importante que os sistemas de avaliação científica os coloquem em contexto ao considerá-los para a avaliação do desempenho acadêmico

Minimising the stress of weaning of beef calves: a review

Weaning of beef calves is usually done abruptly and early compared to the natural weaning of the species, and is associated with simultaneous exposure of calves to a range of social and environmental stressors. Behavioural and physiological responses to weaning indicate detrimental effects on the welfare of these animals. The development and assessment of weaning methods aiming at reducing or avoiding this problem must be supported by scientific knowledge of the morphological, physiological and psychological mechanisms involved in the establishment, maintenance and braking of the cow-calf bond. Solutions also depend on the understanding of the various stressors associated with weaning, among which are the change in diet, cessation of nursing, separation from the dam, the change to a new spatial environment and the need for social reorganization following removal of the adults from the group. This review discusses these issues and assesses the effectiveness of the methods so far proposed for improving the welfare of beef calves during the weaning period

Comportamiento homosexual en rumiantes machos. Revisión

In several male ruminants, including both, domestic and wild species, it has been reported the presence of homosexualbehaviour  between  males.  The  aim  of  this  review  was  to  summarize  the  information  about  neuroendocrinologicaldifferences  between  homo  and  heterosexual  individuals,  and  the  relationship  between  homosexual  behaviour  andsexual steroid concentration. Moreover, we present information that link homosexual behavior with social dominance,age,  social  environment  during  the  developmental  period,  and  environment  disturbances.  Therefore,  we  includeinformation  about  other  physiologic  aspects,  such  as  reproductive  seasonality,  including  unpublished  informationabout  seasonal  changes  in  domestic  rams  and  captive  male  Iberian  ibex,  and  the  relationship  between  seasonalchanges  in  testosterone  and  behaviour.  Other  topic  discussed  is  the  “buller  syndrome”,  which  is  commonly  observedin  steers,  in  which  is  observed  that  some  males  are  repeatedly  mounted  by  others  males.  In  brief,  homosexualbehaviour  in  male  ruminants  is  multietiologic,  and  some  aspects  are  understudied,  so  the  interpretation  may  becautiously  considered  before  deep  studies  are  developed.En varias especies de rumiantes, tanto domésticos como silvestres, se ha reportado la existencia del comportamiento homosexual entre los machos. El objetivo de esta revisión fue sintetizar la información disponible sobre las diferencias neuroendocrinas entre individuos homo y heterosexuales, y la relación entre la presencia del comportamiento homosexual y la concentración de esteroides sexuales. A su vez, se presenta información que vincula el comportamiento homosexual con la dominancia social, la edad, el ambiente social durante el desarrollo, y los disturbios ambientales. También se analiza como varía el comportamiento homosexual de acuerdo a la estacionalidad reproductiva. Además, se incluye información original sobre la estacionalidad del comportamiento homosexual en carneros domésticos, y de machos de cabra montesa, y su vínculo con la secreción de testosterona. Otro aspecto discutido es el “síndrome de buller” en novillos, individuos que son sistemáticamente montados por otros, y algunos de los factores asociados con la ocurrencia de este síndrome. En síntesis, el comportamiento homosexual en los rumiantes machos tiene un origen etiológico diverso, estando algunos aspectos aún poco estudiados, por lo que toda interpretación debe ser considerada con cautela, siendo por lo tanto un campo de estudio a profundizar

Farm animal welfare indicators: a critical review

The aim of this review was to analyze and discuss the use of different indicators of animal welfare (AW) in farm animals. Practices such as castration, tail docking, weaning, transport and slaughter induce a stress response, often accompanied by pain and injuries. This can affect the productive results, both in quantity and quality of the product, and have a negative impact on AW. In this review, we discuss a number of indicators of AW and propose that a combination of them should be used to assess AW in farm animals. Many indicators of AW have been validated for certain types of handling and production systems, mainly in European countries. However, since environment, management and production systems may influence the stress response, it is necessary to develop indicators appropriate to production systems in Latin America

Exposure to the mother activates the main olfactory bulb of lambs

The brain structures by which the lamb recognizes and bonds to its’ mother are unknown. The aim of this study was to compare the neuronal activation of the main olfactory bulb (MOB) of lambs exposed to their mothers, lactating ewes or no social stimuli. The testing pen consisted of two similar pens (3mx2m) separated by a metallic fence. At separation, suckling lambs of one month of age were isolated for 90 min in one area of the testing pen. Thereafter, either the mother (n=10; group MOT) or a lactating-ewe (n=9; group LE) were introduced to an adjacent pen for another 90 min. In the third group, lambs remained isolated (n=9, group ISO). Neuronal activation was investigated 90 min later according to the time required for maximum c-Fos expression in sheep. A lamb was considered to be in the contact zone of a ewe when it was less than 80 cm from it. The time spent by the lamb walking in the contact zone, the time sniffing the ewe, the number of vocalizations and contact attempts with the ewe were recorded during the first 20 min. Thereafter, the lambs were anaesthetized with an I.V. injection of sodium thiopental (12.5 mg/kg) followed by bleeding. The MOBs were dissected and fixed in paraformaldehyde and stored in sucrose solution. The MOBs were sectioned using a cryostat, and sections were used for c-Fos immunohistochemistry. The number of c-Fos-positive cells in the granular layer of the MOB (12 sections/animal) was measured using a light microscope, and the density of labelled cells was determined using the Mercator software. The lambs of the three groups differed in the time walking (3.1±17 s, 29.4±10.0s and 210.5±37.6s; for ISO, LE and MOT lambs, respectively, P<0.0001). MOT and LE lambs vocalized more than ISO lambs (17.3±4.7 and 7.4±4.5 vs 0.1±0.1;P=0.01 and P=0.02, respectively). MOT lambs attempted to reunite with their mother more than LE lambs did with the lactating ewe (21.7±5.8 vs 2.6±1.0;P=0.04), sniffed more often the mother (13.3±3.3 vs 4.0±1.1;P=0.01), and tended to do so during more time (27.1±11.1s vs 4.9±1.4s;P=0.059). C-Fos immunoreactivity differed according to the treatment (P=0.049): it was greater in MOT than ISO lambs (1.59±0.27X10-3mm3 vs 1.17±0.26X10-3mm3; P=0.014), while LE lambs had intermediate values that did not differ from any (1.38±0.28X10-3mm3). Recognition of the mother is accompanied with an increased activation of the MOB of lambs, suggesting that olfactory cues from the mother are important for the recognition process.Agencia Nacional de Investigación e Innovació

Influence of Prolactin Secretion Changes on Sperm Head Size and Freezability in Ibex and Mouflon

Aim: This work examined the influence of induced changes in prolactin (PRL) secretion on sperm cryoresistance of ibex and the mouflon. Materials and Methods: PRL secretion was modified in a first experiment by the use of bromocriptine (BCR, dopamine agonist) during the non-breeding season, and in a second experiment by the use of sulpiride (SLP, dopamine D2-receptor antagonist) during the rutting season. Slow and ultra-rapid freezing protocols were used to cryopreserve sperm samples. Results: BCR decreased blood plasma PRL concentrations, whereas SLP increased them. Cryoresistance ratios (CRs) for curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP) in BCR-treated mouflons were lower than in controls using slow-freezing (p < 0.05), while CRs of motility and morphologically normal sperm of BCR-treated mouflons were greater than controls with ultra-rapid freezing (p < 0.05). BCR increased the head sperm dimensions in ibexes (p < 0.001); conversely, BCR decreased the head dimensions in mouflons (p < 0.001). CR-motility, CR-amplitude of lateral head displacement (ALH), CR-viability, and CR-acrosome integrity in SLP-treated mouflons were lower than in controls with slow-freezing (p < 0.01); CR-viability and CR-acrosome were lower than controls with ultra-rapid freezing (p < 0.05). In ibexes, CR-ALH was lower for SLP-treated (p < 0.05). SLP treatment increased head dimensions in ibexes (p < 0.001) but did not affect the sperm head of mouflons. Conclusion: Our findings show that high levels of blood plasma PRL negatively affect the cryoresistance of ibex and mouflon sperm.Peer reviewe

Reproductive biology of the pampas deer (Ozotoceros bezoarticus): a review

The pampas deer (Ozotoceros bezoarticus) is a South American grazing deer which is in extreme danger of extinction. Very little is known about the biology of the pampas deer. Moreover, most information has not been published in peer-reviewed scientific journals, and is only available in local publications, theses, etc. Therefore, our aim was to update and summarize the available information regarding the reproductive biology of the pampas deer. Moreover, in most sections, we have also included new, unpublished information. Detailed descriptions are provided of the anatomy of both the female and the male reproductive tract, puberty onset, the oestrous cycle and gestational length. Birthing and the early postpartum period are described, as are maternal behaviour and early fawn development, seasonal distribution of births, seasonal changes in male reproduction and antler cycle, reproductive behaviour, semen collection, and cryopreservation. Finally, an overview is given and future directions of research are proposed

Reproductive responses of anestrous ewes to the introduction of rams

This thesis summarises and discusses results of studies concerning the ovarian and endocrine responses of anestrous ewes to the ram effect, the relation between the use of progestogen primings and the reproductive response of anestrous and cyclic ewes to the ram effect, and the endocrine and testicular changes in rams used to stimulate anestrous ewes. Ovarian responses to the ram effect (monitored ultrasonographically) were highly variable. Ewes responded with two luteal phases (short and normal, respectively), delayed ovulations (Days 5-7) followed by normal or short luteal phases, luteinization of non-ovulatory follicles, luteinized follicular cyst and no luteal phase. There was no relation between the growth status of the largest follicle present when rams were introduced and the ovarian responding pattern of anoestrous ewes to the ram effect. Similar results in estrus incidence and fertility were obtained after using intravaginal sponges containing medroxyprogesterone acetate (MAP) for 6, 9, or 13 days. Priming with sponges containing 20, 40, or 60 mg of MAP for 6 days gave similar reproductive results. Six-day primings with sponges impregnated with MAP or fluorogestone acetate, or intravaginal devices containing progesterone (CIDR) were equally effective in improving the response to the ram effect. A single administration of 2.5 mg of MAP 1, 3, or 5 days before the introduction of the rams concentrated estrus in ewes 17 to 20 days later. In MAP-primed ewes, the endocrine pattern of the induced follicular phase of ewes that came into estrus was similar to a normal follicular phase, in ewes that ovulated without expressing estrus no significant increase in estradiol-17b or decrease in FSH was observed. The ram effect does not seem to affect the ovarian response of cyclic ewes during the midbreeding season. Rams used to stimulate anestrous ewes show an increase in LH and testosterone concentrations beginning at 12 h after joining, and high concentrations are maintained while estrous ewes are present and mating takes place in the flock. The response of rams to estrous ewes may be at least part of the mechanism by which anestrous ewes submitted to the ram effect express maximum reproductive response when ewes in estrus are introduced together with the rams