Interação reprodução x produção na ovinocultura: Aspectos reprodutivos relacionados com produtividade / Reproduction x production interaction in sheep farming: Reproductive aspects related to productivity

A importância dos manejos reprodutivos, que contribui para o avanço da ovinocultura e rentabilidade dos sistemas, revela oportunidades para trabalho com a interação reprodução x produção. Estratégias para incremento produtivo no setor, através de biotécnicas reprodutivas, que permitem redução da idade a puberdade, diminuição da estacionalidade reprodutiva e aumento da taxa ovulatória. Além das possibilidades hormonais, métodos alternativos que consideram efeito macho e nutrição, são considerados eficiente para controle do ciclo. Este artigo tem como objetivo revisar os protocolos de controle do ciclo estral e incremento produtivo na ovinocultura.(AU)

The importance of reproductive management, which contributes to the advancement of sheep farming and the profitability of the systems, reveals opportunities for work with the reproduction x production interaction. Strategies to increase production in the sector, through reproductive biotechniques, which allow reducing the age at puberty, reducing reproductive seasonality and increasing the ovulatory rate. In addition to hormonal possibilities, alternative methods that consider male effect and nutrition are considered efficient for cycle control. This article aims to review the estrous cycle control protocols and productive increase in sheep farming.(AU)

Atualizações no controle do ciclo estral em ovinos / Updates on the control of the estrous cycle in sheep

Nos últimos anos, observou-se um aumento no tamanho do rebanho ovino no país, indicando uma retomada na ovinocultura. Para melhorar a eficiência reprodutiva desses animais, a utilização de biotécnicas tem se mostrado uma ferramenta importante. Dentre essas biotécnicas, destacam-se os protocolos de sincronização do ciclo estral, os quais frequentemente utilizam progesterona associada a gonadotrofinas ou análogos da prostaglandina em duas aplicações. Este artigo tem como objetivo revisar os protocolos de sincronização utilizados em ovinos e apresentar atualizações relevantes sobre os mesmos.(AU)

In recent years, there has been an increase in the size of the sheep herd in the country, indicating a recovery in sheep farming. To improve the reproductive efficiency of these animals, the use of biotechniques has been shown to be an important tool. Among these biotechniques, estrous cycle synchronization protocols stand out, which frequently use progesterone associated with gonadotropins or prostaglandin analogues in two applications. This article aims to review the synchronization protocols used in sheep and present relevant updates about them.(AU)

Reproductive response of synchronized and extensively grazed Blackbelly ewes during the summer in the tropics

The present experiment aimed to evaluate the reproductive response of Blackbelly ewes synchronized with low doses of eCG during the summer in a tropical climate. Sixty multiparous hair ewes were divided into three groups (20 ewes/group): control group (CG; 0 IU of eCG), treated group 1 (TG-1; 140 IU of eCG) and treated group 2 (TG-2; 300 IU of eCG). The study found that the three groups of ewes showed differences in their reproductive behavior (P < 0.01). Indeed, all the ewes in the TG-1 and TG-2 groups presented a higher response to estrus than the CG (P < 0.01). In the same way, TG1 and TG-2 had an onset to estrus in less time (P < 0.01). On the other hand, prolificacy was also higher in TG-1 and TG-2 (P < 0.05). Likewise, ewes from TG-1 and TG-2 had more lambs than those from CG (P < 0.05). On the other hand, the variables of fertility and gestation length were similar regardless of the group of ewes (P > 0.05). It´s concluded that the ewes treated with eCG presented good reproductive behavior, and the majority did so in the first 24 to 36 h after removing the intravaginal device.

Reproductive and economic evaluation of sexual stimulation during the anestrous period in a commercial farm with neonatal lamb losses / Avaliação reprodutiva e econômica da estimulação sexual durante o período antrópico em uma fazenda comercial com perdas neonatais de cordeiros

This study was performed during the anestrous, involving 140 Akkaraman Kangal ewes whose lambs had died in the neonatal stage due to pneumonia and enteritis. Intravaginal sponge containing progesterone was placed to the animals (Group 1, n = 70) on day 0 and removed after 7 days, following which 263 µg PGF2α and 500 IU eCG were administered to the sheep. Ram introduction was performed for 7 days (days 8-14), starting from the day after the removal of the intravaginal sponge (day 8). The animals in Group 2 (n = 70) were not exposed to any treatment. Ram introduction was performed simultaneously in both the groups. To determine the reproductive response, reproductive parameters such as estrous, pregnancy, multiple pregnancy, and embryonic mortality rates, number of births, number of offspring, and fertility, as well as their economic implications, were compared between groups. Each reproductive parameter exhibited a statistical difference between groups. An economically positive trend was observed in the study group compared with the control group. It was concluded that in case of lamb losses in commercial farms that derive profit from lambing, pregnancy of ewes can be achieved via sexual stimulation without waiting for the next breeding season.

Este estudo foi realizado durante o anestrous, envolvendo 140 ovelhas Akkaraman Kangal cujos cordeiros haviam morrido no estágio neonatal devido a pneumonia e enterite. A esponja intragaginal contendo progesterona foi colocada aos animais (Grupo 1, n = 70) no dia 0 e removida após 7 dias, após os quais 263 µg PGF2α e 500 UI eCG foram administrados às ovelhas. A introdução do carneiro foi realizada por 7 dias (dias 8-14), a partir do dia seguinte à remoção da esponja intravaginal (dia 8). Os animais do Grupo 2 (n = 70) não foram expostos a nenhum tratamento. A introdução do carneiro foi realizada simultaneamente em ambos os grupos. Para determinar a resposta reprodutiva, foram comparados entre os grupos parâmetros reprodutivos, tais como estrogênio, gravidez, gravidez múltipla e taxas de mortalidade embrionária, número de nascimentos, número de descendentes e fertilidade, bem como suas implicações econômicas. Cada parâmetro reprodutivo exibia uma diferença estatística entre os grupos. Uma tendência economicamente positiva foi observada no grupo de estudo em comparação com o grupo de controle. Concluiu-se que no caso de perdas de cordeiros em fazendas comerciais que obtêm lucros com a parição, a gravidez de ovelhas pode ser obtida através de estimulação sexual sem esperar pela próxima estação de reprodução.

Production and economic evaluation of the Corriedale, Highlander and Milchschaf sheep breeds in Southern Uruguay / Produção e avaliação econômica das raças ovinas Corriedale, Highlander e Milchschaf no Sul do Uruguai

Sheep production is expanding among small farmers in Southern Uruguay. Currently, Corriedale and Milchschaf are being used, but not Highlander. However, there is lack of experimental information regarding the relative performance of these breeds. We conducted an experiment where these three sheep breeds were run together at the Southern Regional Centre, located in the region in question. Wool, body, reproductive and lamb growth traits were recorded from 2015 to 2019. Results were used as a basis for the calculation of gross margins for each breed, which we calculated for a range of production and economic scenarios. For scenarios based on the results of the present study Highlander was the best performing breed. If it was assumed to be wool-less, it performed even better. In some scenarios Corriedale performed best, especially when the higher wool price it used to enjoy was assumed. However, fetching such a price in the foreseeable future is unlikely. We concluded that in the absence of wool-less sheep that perform in a manner similar to Highlander or Milchschaf in terms of reproduction and lamb growth, Highlander is currently the best option for small farmers in Southern Uruguay. Until now, Milchschaf has been the recommended breed for the region and production system in question. The recommendation should be reviewed, Highlander should be recommended instead, and the performance of wool-less breeds should be investigated. Results could be applicable to other temperate regions in Latin America where similar production systems exist or may be developed.

A produção de ovinos está se expandindo entre os pequenos produtores do Sul do Uruguai. Corriedale e Milchschaf estão sendo utilizados atualmente, mas não Highlander. Não obstante, há uma falta de informações experimentais sobre o desempenho relativo destas raças. Realizamos um experimento no qual estas três raças ovinas foram manejadas juntas no Centro Regional Sul, localizado na região em questão. As características de lã, corpo, reprodução e crescimento do cordeiro foram registradas de 2015 a 2019. Os resultados foram usados como base para calcular as margens brutas para cada raça, o que fizemos para uma série de cenários de produção e econômicos. Nos cenários baseados nos resultados deste estudo, a raça Highlander foi a que teve melhor desempenho. Se, se supunha que não tinha lã, seu desempenho era ainda maior. Em alguns cenários, Corriedale foi a raça com melhor desempenho, particularmente quando se supôs preços mais altos da lã, como os que se obtinham anos atrás. No entanto, é improvável que estes preços sejam atingidos novamente num futuro próximo. Concluímos que, na ausência de ovelhas sem lã, que tenham um desempenho semelhante ao Highlander ou Milchschaf em termos de reprodução e crescimento do cordeiro, Highlander é atualmente a melhor opção para os pequenos produtores do sul do Uruguai. Até agora, Milchschaf tem sido a raça recomendada para a região e para o sistema de produção em questão. Esta recomendação deve ser revista, o Highlander deve ser a raça recomendada, e o desempenho das raças sem lã deve ser investigado. Os resultados poderiam ser aplicáveis a outras regiões temperadas da América Latina onde sistemas de produção similares existem ou podem ser desenvolvidos.

Production and economic evaluation of the Corriedale, Highlander and Milchschaf sheep breeds in Southern Uruguay / Produção e avaliação econômica das raças ovinas Corriedale, Highlander e Milchschaf no Sul do Uruguai

ABSTRACT: Sheep production is expanding among small farmers in Southern Uruguay. Currently, Corriedale and Milchschaf are being used, but not Highlander. However, there is lack of experimental information regarding the relative performance of these breeds. We conducted an experiment where these three sheep breeds were run together at the Southern Regional Centre, located in the region in question. Wool, body, reproductive and lamb growth traits were recorded from 2015 to 2019. Results were used as a basis for the calculation of gross margins for each breed, which we calculated for a range of production and economic scenarios. For scenarios based on the results of the present study Highlander was the best performing breed. If it was assumed to be wool-less, it performed even better. In some scenarios Corriedale performed best, especially when the higher wool price it used to enjoy was assumed. However, fetching such a price in the foreseeable future is unlikely. We concluded that in the absence of wool-less sheep that perform in a manner similar to Highlander or Milchschaf in terms of reproduction and lamb growth, Highlander is currently the best option for small farmers in Southern Uruguay. Until now, Milchschaf has been the recommended breed for the region and production system in question. The recommendation should be reviewed, Highlander should be recommended instead, and the performance of wool-less breeds should be investigated. Results could be applicable to other temperate regions in Latin America where similar production systems exist or may be developed.

RESUMO: A produção de ovinos está se expandindo entre os pequenos produtores do Sul do Uruguai. Corriedale e Milchschaf estão sendo utilizados atualmente, mas não Highlander. Não obstante, há uma falta de informações experimentais sobre o desempenho relativo destas raças. Realizamos um experimento no qual estas três raças ovinas foram manejadas juntas no Centro Regional Sul, localizado na região em questão. As características de lã, corpo, reprodução e crescimento do cordeiro foram registradas de 2015 a 2019. Os resultados foram usados como base para calcular as margens brutas para cada raça, o que fizemos para uma série de cenários de produção e econômicos. Nos cenários baseados nos resultados deste estudo, a raça Highlander foi a que teve melhor desempenho. Se, se supunha que não tinha lã, seu desempenho era ainda maior. Em alguns cenários, Corriedale foi a raça com melhor desempenho, particularmente quando se supôs preços mais altos da lã, como os que se obtinham anos atrás. No entanto, é improvável que estes preços sejam atingidos novamente num futuro próximo. Concluímos que, na ausência de ovelhas sem lã, que tenham um desempenho semelhante ao Highlander ou Milchschaf em termos de reprodução e crescimento do cordeiro, Highlander é atualmente a melhor opção para os pequenos produtores do sul do Uruguai. Até agora, Milchschaf tem sido a raça recomendada para a região e para o sistema de produção em questão. Esta recomendação deve ser revista, o Highlander deve ser a raça recomendada, e o desempenho das raças sem lã deve ser investigado. Os resultados poderiam ser aplicáveis a outras regiões temperadas da América Latina onde sistemas de produção similares existem ou podem ser desenvolvidos.

Uso da ultrassonografia Doppler colorido na reprodução de pequenos ruminantes / Use of color Doppler ultrasonography in the reproduction of small ruminants

A ultrassonografia (US) Doppler colorido fornece uma ferramenta não invasiva valiosa para detectar e monitorar mudanças dinâmicas na rede vascular e fluxo sanguíneo em vários órgãos e tecidos reprodutivos. Em apoio as biotécnicas da reprodução animal assistida, a US Doppler colorido tem mostrada alta eficiência no monitoramento funcional das estruturas ovarianas. A previsão de respostas ovarianas e produções embrionária em ovinos pela identificação de sinais Doppler na parede folicular já se mostrou eficiente. A aplicação da US Doppler colorido para a identificação da funcionalidade do tecido luteal é ainda maior, desde acompanhamentos fisiológicos e diagnósticos de disfunções luteais até ampla aplicação em conjunto as diferentes biotécnicas reprodutivas. Destaca-se em ovelhas e cabras, a aplicação comercial da US Doppler colorido para o diagnóstico de gestação precoce, de disfunções luteais, de determinação de respostas ovarianas em fêmeas doadoras e receptoras de embriões, para identificar efeitos luteotrófico de estratégias hormonais, e ainda para amparar as estratégias de ressincronização de estro.(AU)

Color Doppler ultrasonography (US) provides a valuable non-invasive tool for detecting and monitoring dynamic changes in the vascular network and blood flow in various reproductive organs and tissues. In support of assisted animal reproduction biotechniques, color Doppler US has shown high efficiency in the functional monitoring of ovarian structures. The prediction of ovarian responses and embryonic production in sheep by identifying Doppler signals in the follicular wall has already proved to be efficient. The application of color Doppler US for identifying the functionality of the luteal tissue is even greater, from physiological monitoring and diagnosis of luteal dysfunctions to wide application together with different reproductive biotechniques. It stands out in sheep and goats, the commercial application of color Doppler US for the diagnosis of early pregnancy, luteal dysfunctions, determination of ovarian responses in embryo donor and recipient females, to identify luteotrophic effects of hormonal strategies, and even to support estrus resynchronization strategies.(AU)

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)

Frontiers in sheep reproduction - making use of natural responses to environmental challenges to manage productivity

This review addresses advances, directions and opportunities for research on sheep reproduction in the context of the global challenges of food security and climate change, and demand for 'clean, green and ethical' (CGE) animal management. The foundation of CGE management is an understanding of the physiological processes through which the reproductive system responds to changes in the animal's environment. These days, to the main environmental factors (photoperiod, nutrition, pheromones), we need to add stress from extreme weather events. With respect to nutrition in rams, we now have a deeper understanding of the responses of the brain centres that control gonadotrophin secretion (the kisspeptin system). At testis level, we have found that nutrition affects non-coding RNAs in Sertoli cells and germ cells, thus affecting the balance between cell proliferation and apoptosis. This proliferation-apoptosis balance is also affected during prenatal development, when undernutrition or stress in pregnant ewes seems to elicit epigenetic changes in developing gonads that could affect offspring fertility in adult life. With respect to nutrition in ewes, metabolic signals act directly on ovarian follicles, and thus change ovulation rate, but the variety of signals now includes the adipokines. An early concern was that nutritional supplements that increase ovulation rate would also increase embryo mortality but we now know that embryo survival is improved under field conditions. Finally, we had always thought that the efficiency gains from early puberty in lambs could only be achieved by accelerating fat accumulation, but we now know that faster muscle growth will achieve the same goal, offering two advantages in meat production systems. With respect to pheromones ('ram effect'), we have a deeper understanding of the brain responses (kisspeptin system) but, most importantly, a realization that the response of ewes to the ram signal involves cell division in memory centres. Many opportunities remain.(AU)

Climate impacts on reproductive performance of Romanov sheep in the moderate climate

This study aimed to investigate the climatological impacts of air temperature, sunshine duration, and rain precipitation, in a moderate climate, on the reproductive performance of Romanov sheep in the continental part of Croatia, during two consecutive years (2019-2020). Our study included 549 matings with 520 successful conceptions at 5 Romanov sheep farms, and the fertility rate was 94.72%. The percentage of lambs delivered in winter was 53.27% (n = 277), in spring 20.19% (n = 105), in summer 14.23% (n = 74) and 12.31% in autumn (n = 64). According to percentile ranks and classification ratings, thermal conditions have been described as very warm (during 2019-2020), while precipitation conditions, expressed in percentiles, were wet (during 2019) but dry (during 2020) for this region. The peak of sexual activity was from mid-August until October in 2019 and from the end of August to November in 2020 for Romanov sheep in northwestern (NW) Croatia. A Kruskal-Wallis test showed a statistically significant difference in the number of pregnant ewes during the different mating seasons in the year (p < 0.001). Therefore, we can assume that air temperature, precipitation volume, and sunshine duration during the different seasons could impact the reproductive performance of Romanov sheep in a moderate climate.(AU)

Comparison of reproductive performance, live weight, survivability, and fleece characteristics of indoor-raised Central Anatolian Merino and Malya sheep

This study was conducted to compare Central Anatolian Merino (CAM) and Malya sheep under intensive conditions in terms of reproductive traits, birth and weaning weights, fattening performance, and some fleece characteristics. In this study, 840 CAM and 194 Malya ewes were used for the comparison of reproductive performance, whereas 740 and 211 lambs were used to compare growth traits between the two breeds. Additionally, the fattening performance of 61 CAM and 68 Malya lambs were compared. Finally, for the comparison of wool quality traits, 94 CAM and 90 Malya lambs were used. The lambs were kept together with the sheep that gave birth to them for 10 days. After this period, lambs were given lamb starter feed, alfalfa hay, and vetch hay in addition to milk. When lambs reached 40 days old, they were taken to the pasture with the sheep. In this period, pasture grass, growing lamb concentrate feed, alfalfa hay, and vetch hay were given in addition to milk. Lambs were weaned when they reached an average age of 90 days, and their live weights were determined. A determined number of lambs was selected from weaned male lambs. For these animals, in the fattening period, barley, alfalfa hay, vetch hay, meadow hay, and lentil straw were provided ad libitum in addition to 400 g/day/head of fattening feed. This study indicated that birth rate was better for CAM sheep than for Malya sheep. However, Malya lambs may have more advantages than CAM lambs in terms of survival and fattening performance. Although birth weight was higher for Malya sheep than for CAM sheep, the opposite result was observed for the weaning weight. The beginning weights of fattened male lambs were higher for CAM lambs than for Malya lambs, but the ending weights of both fattened groups were similar.(AU)

Effects of milking system in suckling period on growth, reproduction traits, and milk yield of East Friesian-cross dairy sheep

The main objective of this study was to determine the effects of milking system on growth, reproduction, and milk yield and composition of East Friesiancross (Tahirova) dairy sheep that were milked in the evening during the suckling period. A total of 43 Tahirova ewes and 58 lambs were used in the present study. One of the groups was milked in the evening (evening milked; EM) before coming together with their lambs, and the other group was not (not milked in the evening; NEM). Morning milking was performed in both groups during the study. Lambs in both groups were individually weaned at the age of 60 days. There was no statistical difference between the lambs' live weight at weaning in the EM and NEM groups, determined to be 23.46 and 24.11 kg, respectively. Live weight values of lambs were similar in the groups at ages of up to 180 days. The reproductive characteristics of ewe lambs in the EM and NEM groups, having similar growth rates and a similar live weight and body condition in the first estrus stages, were also similar. The return rate and frequency of return were close in both groups of ewe lambs. Milk yield of the NEM group was significantly higher than that of the EM group before and after weaning. However, in groups with similar lactation milk yield and length, the total marketable milk yield was higher in the suckling period of the EM group. The milking system in suckling period of Tahirova ewes does not significantly affect growth, average daily gain, and reproductive characteristics. Milk yield in the NEM group before and after weaning was significantly higher than the EM group, but the total marketable milk yield was higher in the EM group.(AU)

Effect of seasonally changing aerial environment on testosterone in Karagouniko and Chios sheep

A well-established activity in Greece and other Mediterranean countries is sheep farming. Karagouniko and Chios sheep are promising breeds and targets for the reproductive physiologist's attention. Under this context, part of the reproductive physiology of Karagouniko and Chios was investigated, taking into account the environment. Specifically, four time periods were considered; April-June (Long days, increasing photoperiod length), July-September (Long days, decreasing photoperiod length), October-December (Short days, decreasing photoperiod length), and January-March (Short days, increasing photoperiod length). The effect of the period on the concentration of the testosterone (main male hormone) in rams of the breeds above was studied, by using repeated measures analysis of variance, also taking into account the environmental variables air temperature, relative humidity, sunshine, rainfall, and photoperiod, in the Artificial Insemination Center of Karditsa (39°21’18’’N, 21054’19’’E), Greece. The lowering of photoperiod from April-June to July-September (long days) and afterward, even more to October-December (short days) coincided with a progressive increase of testosterone in both breeds. Photoperiod seems to have a major role in the concentration of Karagouniko and Chios breeds' testosterone compared to the other environmental variables. When considering the whole experimental period, Chios sheep had significantly higher (P < 0.05) testosterone (1.95 ng/ml) than the Karagouniko one (1.55 ng/ml). Our findings could contribute towards the more rational exploitation of the examined sheep breeds.

Effect of seasonally changing aerial environment on testosterone in Karagouniko and Chios sheep

A well-established activity in Greece and other Mediterranean countries is sheep farming. Karagouniko and Chios sheep are promising breeds and targets for the reproductive physiologist's attention. Under this context, part of the reproductive physiology of Karagouniko and Chios was investigated, taking into account the environment. Specifically, four time periods were considered; April-June (Long days, increasing photoperiod length), July-September (Long days, decreasing photoperiod length), October-December (Short days, decreasing photoperiod length), and January-March (Short days, increasing photoperiod length). The effect of the period on the concentration of the testosterone (main male hormone) in rams of the breeds above was studied, by using repeated measures analysis of variance, also taking into account the environmental variables air temperature, relative humidity, sunshine, rainfall, and photoperiod, in the Artificial Insemination Center of Karditsa (39°21'18''N, 21°54'19''E), Greece. The lowering of photoperiod from April-June to July-September (long days) and afterward, even more to October-December (short days) coincided with a progressive increase of testosterone in both breeds. Photoperiod seems to have a major role in the concentration of Karagouniko and Chios breeds' testosterone compared to the other environmental variables. When considering the whole experimental period, Chios sheep had significantly higher (P < 0.05) testosterone (1.95 ng/ml) than the Karagouniko one (1.55 ng/ml). Our findings could contribute towards the more rational exploitation of the examined sheep breeds.(AU)

Climate impacts on reproductive performance of Romanov sheep in the moderate climate

This study aimed to investigate the climatological impacts of air temperature, sunshine duration, and rain precipitation, in a moderate climate, on the reproductive performance of Romanov sheep in the continental part of Croatia, during two consecutive years (2019-2020). Our study included 549 matings with 520 successful conceptions at 5 Romanov sheep farms, and the fertility rate was 94.72%. The percentage of lambs delivered in winter was 53.27% (n = 277), in spring 20.19% (n = 105), in summer 14.23% (n = 74) and 12.31% in autumn (n = 64). According to percentile ranks and classification ratings, thermal conditions have been described as very warm (during 2019-2020), while precipitation conditions, expressed in percentiles, were wet (during 2019) but dry (during 2020) for this region. The peak of sexual activity was from mid-August until October in 2019 and from the end of August to November in 2020 for Romanov sheep in northwestern (NW) Croatia. A Kruskal-Wallis test showed a statistically significant difference in the number of pregnant ewes during the different mating seasons in the year (p < 0.001). Therefore, we can assume that air temperature, precipitation volume, and sunshine duration during the different seasons could impact the reproductive performance of Romanov sheep in a moderate climate.

Economic performance of highenergy diets and supplementation with chromium propionate or calcium salts of palm oil in ewes' production

The experiment aimed to analyze the economic viability of using highenergy diets and the supplementation of chromium propionate or calcium salts of palm oil in the diet of ewes from the late gestation until the end of lactation. Seventy-two ewes of Santa Ines × Dorper crossbreeds were allocated to five treatments: CTL (n = 14) with 100% of NRC recommendation for metabolizable energy per kg dry matter intake (ME/kg DMI), LOW (n = 14) with 90% ME/kg DMI, HIGH (n = 15) with 110% ME/kg DMI, Cr (n = 15) HIGH diet plus chromium propionate, and FAT (n = 14) HIGH diet plus calcium salts of palm oil. Based on the performance data, a short-term analysis was performed for a module of 1000 ewes, evaluating costs, revenues, and profitability, and long-term analysis was performed by an additional cash flow of 120 months. The CTL and FAT treatments were not viable due to higher costs and lower revenues, and they also had a negative net present value (NPV) and internal rate of return (IRR). The LOW treatment, despite lower costs and positive profitability, had a negative NPV (-$872.90) and IRR (1.85%) that was below the discount rate, making it unprofitable in the long run. The HIGH and Cr treatments were considered feasible because they had lower unit costs and higher profitability, in addition to a high NPV ($64,894.11 and 104,902.05, respectively) and a higher IRR (9.03% and 13.65%, respectively) than the discount rate. The use of high-energy diets, with added chromium propionate, promoted better performance and, consequently, better economic return.(AU)

Congenital cataract in a Blackbelly lamb

Background: A cataract is an opacity of the crystalline structure that results in impaired vision. The congenital form manifests itself at birth or shortly thereafter and might also be inherited and therefore capable of passing on to descendants. Cataracts can be caused by systemic diseases, medications, toxic substances, radiation, metabolic alterations, dietary deficiencies, inflammation, traumatic injuries, age, or genetic factors. The few Blackbelly sheep herds are located in the northeast and north regions of Brazil and are considered rare, which could result in high levels of consanguinity. In this context, we report a case of congenital cataract in a Blackbelly lamb and its possible etiology. Case: A 3-month-old lamb presented with ophthalmic alterations since birth, with white and cloudy spots in both eyes and impaired vision. In the same herd, 3 elderly sheep showed similar ophthalmic alterations. The lamb was able to follow its dam, but when walking, bumped into small objects or very close to his vision field. The lamb managed to follow the herd and dodge large objects, suggesting partial vision loss. During a physical examination, both lens showed opacity and reduced corneal reflex, pupillary reflex to direct light, pupillary reflex to consensual light, and threat reflex. Ultrasonographic examination revealed that both lens presented hyperechogenicity. Hematological values were within the reference limits. In the same herd, three elderly sheep presented bilateral cataracts (2 rams and 1 ewe) in previous years, which at that time was attributed to natural aging. One ram was the lamb's grandfather. The other ram was the father of the female, both with cataracts. Based on history, physical examination, and complementary examinations, the lamb was diagnosed with bilateral congenital cataracts with a probable hereditary condition. Discussion: Multiple factors can be related to the etiology of cataracts, and it can be difficult to establish the correct etiology. Regarding the age of onset, cataracts can be classified mainly as congenital and senile. Senile cataract is a bilateral opacification process that involves the entire lens, with slow progression and gradual loss of vision with increasing age. In adult sheep, the high proportion of eyes affected by spontaneously arising cataracts could be related to age, increased exposure to sunlight, increased genetic susceptibility, or a combination of these factors. In this case, the herd had three adult elderly sheep with cataracts previously characterized as senile. However, after reviewing the genealogy, it was found that all animals had some degree of parentage, suggesting a hereditary factor. Congenital cataracts are expressed soon after birth, resulting from the malformation of fibers in the lens, and are generally nonprogressive. The congenital form may or may not be associated with hereditary factors. Inheritance cataracts have been reported in several breeds of dogs and usually occur as an autosomal recessive trait. Blackbelly sheep are rare in Brazil, favoring consanguinity, so we believe that cataracts are inherited in this herd. To control this ophthalmic alteration, all animals with crystalline opacities were excluded from reproduction, and the herd should be monitored in future cases.

Application of natural antioxidants in animal reproduction / Aplicação de antioxidantes naturais na reprodução animal

Antioxidants are natural or synthetic substances that delay oxidation through one or more mechanisms, such as scavenging free radicals, inhibiting lipid peroxidation, and complexing with metals, inhibiting tissue destruction via oxidation. Antioxidants are commonly used in animal feed and the food industry to prevent the oxidation of animal-origin products. Moreover, natural oxidants are used increasingly in animal reproduction, especially for semen preservation. In this context, this study aimed to review the applications of natural antioxidants in animal reproduction. We observed that the bulk of the natural antioxidants, approximately 80.4%, were commercially acquired and used mainly for semen cooling/freezing (72%) with promising results (90%) in Sus scrofa (boar), Capra aegagrus hircus (goat), Gallus gallus domesticus (rooster), and Ovis aries (ram). However, further studies are needed to help determine the appropriate dosage of natural antioxidants for applications.

Antioxidantes são substâncias naturais ou sintéticas que facilitam o retardo da oxidação por um ou mais mecanismos, como sequestrar radicais livres, inibir a peroxidação lipídica e complexar com metais, inibindo a destruição tecidual via oxidação. Antioxidantes são comumente usados na alimentação animal e na indústria alimentícia para prevenir a oxidação de produtos de origem animal. Além disso, os oxidantes naturais estão sendo cada vez mais aplicados na reprodução animal, principalmente na preservação do sêmen. Nesse contexto, este trabalho teve como objetivo revisar a aplicação de antioxidantes naturais na reprodução animal. Observamos que os antioxidantes naturais foram geralmente adquiridos comercialmente (80,4%) e utilizados principalmente no resfriamento/congelamento de sêmen (72%) com resultados promissores (90%) em Sus scrofa (javali), Capra aegagrus hircus (cabra), Gallus gallus domesticus (galo) e Ovis aries (carneiro). No entanto, mais estudos devem ser realizados para ajudar a regular a dosagem de antioxidantes naturais para sua aplicação.

Effect of different protocols for estrus synchronization on reproductive performance of Santa Inês ewes under Amazon environmental conditions

The objective of this study was to evaluate the effect of different hormonal protocols on the reproductive performance of Santa Inês ewes in Amazon environmental conditions. Twenty-two Santa Inês ewes between 3 and 4 years-old were distributed in a randomized block experimental design, where the treatments consisted of two protocols for estrus synchronization (short and long) with eleven animals each. Data on the occurrence of estrus were described for each protocol. Data of estrus, pregnancy, and prolificity were firstly subjected to ANOVA and a subsequent Tukeys test. Results were considered significant at p 0.05. The short-term protocol presented an interesting successful rate, where above 70% ewes tested had estrus. The long-term protocol also achieved a high successful rate, where above 80% ewes tested had estrus. However, comparing the protocols, the long-term protocol presented better results of positive estrus and pregnancy rates in ewes. Thus, it can be concluded that both protocols presented satisfactory results regarding estrus manifestation, and prolificity (lambs produced per ewe). However, under Amazon environmental conditions, the long-term protocol presented better results regarding positive manifestation of estrus and pregnancy rate.(AU)

Effect of different protocols for estrus synchronization on reproductive performance of Santa Inês ewes under Amazon environmental conditions

The objective of this study was to evaluate the effect of different hormonal protocols on the reproductive performance of Santa Inês ewes in Amazon environmental conditions. Twenty-two Santa Inês ewes between 3 and 4 years-old were distributed in a randomized block experimental design, where the treatments consisted of two protocols for estrus synchronization (short and long) with eleven animals each. Data on the occurrence of estrus were described for each protocol. Data of estrus, pregnancy, and prolificity were firstly subjected to ANOVA and a subsequent Tukeys test. Results were considered significant at p 0.05. The short-term protocol presented an interesting successful rate, where above 70% ewes tested had estrus. The long-term protocol also achieved a high successful rate, where above 80% ewes tested had estrus. However, comparing the protocols, the long-term protocol presented better results of positive estrus and pregnancy rates in ewes. Thus, it can be concluded that both protocols presented satisfactory results regarding estrus manifestation, and prolificity (lambs produced per ewe). However, under Amazon environmental conditions, the long-term protocol presented better results regarding positive manifestation of estrus and pregnancy rate.