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)

Farmacopuntura em protocolos de sincronização de estro em pequenos ruminantes / Pharmacopuncture in estrus synchronization protocols in small ruminants

O objetivo com essa revisão foi realizar o levantamento da produção científica disponível e articular saberes a respeito do uso da farmacopuntura associada à protocolos de sincronização de estro principalmente em caprinos e ovinos, como também, em outras espécies de interesse. Ao analisar as pesquisas realizadas nos últimos 10 anos com a utilização de subdoses hormonais associada à farmacopuntura em programas de inseminação artificial em tempo fixo (IATF), nota-se que a farmacopuntura vem se tornando uma ferramenta promissora para viabilizar a redução das doses hormonais administradas e potencializar o efeito do fármaco aplicado, o que eleva a eficiência dos programas de sincronização de estro/ovulação ao reduzir os custos desses protocolos. Além de diminuir o custo desses protocolos para os produtores, nosso grupo de pesquisa realizou uma série de estudos nessa área, visando a busca por protocolos com menores doses hormonais, o que consequentemente reduz a quantidade de resíduos produzidos e promove manejos mais sustentáveis. Baseado nas publicações, pode-se afirmar que a farmacopuntura apresenta resultados satisfatórios e coloca-se como uma via de aplicação de sub-doses ou micro-doses hormonais em protocolos de controle do ciclo estral em caprinos e ovinos, como também, para outras espécies domésticas.(AU)

The objective of this review was to compile information regarding the use of pharmacopuncture associated with estrus synchronization protocols, mainly in goats and sheep, as well as in other species of interest, with the aim of updating and providing information on the subject. When analyzing the research carried out in the last 10 years with the use of hormonal underdoses associated with pharmacopuncture in fixed-time AI programs, these have become a promising tool to enable the reduction of administered hormonal doses and to potentiate the effect of the applied drug, the that increases the efficiency of estrus/ovulation synchronization programs by reducing the costs of these protocols. In addition to reducing the cost of these protocols for producers, our research group carried out a series of studies in this area, aiming at the search for protocols with lower hormonal doses, less waste produced and more sustainable management. Based on the publications, it can be stated that pharmacopuncture presents satisfactory results and is a way of applying sub-doses or micro-doses of hormones in protocols for controlling the estrous cycle in goats and sheep, as well as for other domestic species.(AU)

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)

Estratégias farmacológicas para a manipulação do ciclo estral de fêmeas bovinas de raças de corte taurinas / Pharmacological approaches to manipulate bovine estrous cycle in taurine beef breeds

Este texto discute as estratégias farmacológicas para a manipulação do ciclo estral de fêmeas taurinas de corte, com foco na inseminação artificial em tempo fixo (IATF). Os zebuínos, rebanho predominante no Brasil, apresentam características de ciclo estral diferentes das raças taurinas, o que justifica a busca por estratégias hormonais adaptadas para o controle do ciclo estral nas subespécies. O estradiol combinado com a progesterona (P4) e prostaglandina F2 alfa (PGF) é o esquema hormonal mais comumente utilizado para a manipulação do ciclo estral em protocolos de IATF. Porém, o uso de GnRH combinado ou em substituição aos ésteres de estradiol vem sendo considerado. Coletivamente, os dados do nosso grupo reforçam a necessidade de customizar as abordagens para o controle do ciclo estral de acordo com a composição genética das fêmeas bovinas.(AU)

This text discusses pharmacological strategies to manipulate the estrous cycle of taurine and synthetic females, with a focus on timed artificial insemination (TAI). Zebu cattle, the predominant herd in Brazil, have different estrous cycle characteristics than taurine breeds, requiring different synchronization hormonal strategies for each subspecies. Estradiol combined with progesterone (P4) and prostaglandin F2 alpha (PGF) is the most used hormonal scheme for estrous cycle manipulation in TAI protocols. But the use of GnRH instead of estradiol esters is being considered. Collectively, our group's data reinforce the need to customize approaches to estrous cycle control according to the genetic composition of bovine females.(AU)

Effect of ovarian status on reproductive performance in dairy heifers inseminated with sexed semen

Background: The intensive reproductive management in the dairy farms requires inclusion of a large group of replacement heifers in the breeding program for a shorter period. In this aspect, a creation of effective estrus synchronization protocols with timed artificial insemination (TAI) by sexed semen and optimization of the current ones have a crucial role for obtaining high pregnancy rate. These protocols are beneficial, because they led to reduced interval to first AI, lack of need for estrus detection, and allow obtaining a large group of female calves for on time. Because of limited fertilizing potential of sexed spermatozoa this type of semen is applied mainly for heifers, as fertility is higher compared to lactating cows. The main objective of the present study was to investigate the effect of ovarian status on the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Materials, Methods & Results: Forty-eight Holstein healthy heifers separated in 2 groups were subjected to PGF2α-GnRH pre-treatment and Ovsynch or PRID-5-day estrus synchronization protocol and timed artificial insemination (TAI) with sex-sorted semen, staring 6 days after end of the hormonal pre-treatment. The ovarian status (presence of follicles with or not a corpus luteum) of the heifers at the begin of the treatment, on day of TAI and pregnancy rate in different groups were determined and compared. Additionally, the ovarian status at the begin of the treatment, ovarian status and size of preovulatory follicle (PF) on day of TAI and total values for both groups according to reproductive performance (pregnant or non-pregnant) were also analyzed. On day of TAI the animals with PF and a lack of corpus luteum (CL) in both groups were more that those with PF and CL (39.3% and 30% vs. 60.7 % and 70%), with significant (P < 0.05) difference in PRID-5-day group. The pregnancy rate tended to be higher in PRID-5 day than Ovsynch treatment (65% vs. 35.7%). A higher percentage (100% and 67.9%) of the pregnant animals in both treatments had not CL on day of TAI, and the size of the PF (1.58 ± 0.12 cm and 1.64 ± 0.13 cm) was increased (P < 0.05). Similar effects of the ovarian status on reproductive performance were obtained after a comparison of the total values between pregnant and non-pregnant animals. The percentage of heifers with observed PF without CL on day of TAI was significantly greater (P < 0.05) in pregnant compared to non-pregnant group (91.3% vs. 40%). The opposite dependence was determined for the parameter presence of follicles and corpus luteum (8.7% vs. 60%; P < 0.05). Furthermore, the size of the PF measured immediately before TAI was increased in animals became pregnant (1.60 ± 0.12 cm vs. 1.34 ± 0.17 cm; P < 0.05). Discussion: The analysis of the obtained results showed that the ovarian status on day of TAI affects the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Hormonal pre-treatment with onset of PRID-5-day protocol 6 days later and TAI with sex-sorted semen ensure acceptable pregnancy rate. The greater preovulatory follicle and a lack of corpus luteum before insemination provide significantly (P < 0.05) more pregnant animals, compared to the cases when CL is presented. Ultrasound determination of the ovarian function before insemination can be used in selection of heifers for TAI with sex-sorted semen.

Uso de éguas receptoras acíclicas em programas de transferência de embrião / Anovulatory recipient mares in embryo transfer programs

O maior entrave para o êxito de um programa de transferência de embrião (TE) está relacionado às receptoras, tanto a qualidade de características reprodutivas, quanto a sincronização entre doadoras e receptoras. Éguas doadoras, geralmente, apresentam melhor escore corporal e disponibilidade alimentar nos períodos de seca, fazendo com que iniciem o seu ciclo estral precocemente enquanto éguas receptoras se encontram ainda em anestro ou período transicional, o que dificulta a TE. Vários estudos foram realizados com o objetivo de utilizar receptoras acíclicas como receptoras de embrião. Assim, podem ser utilizadas nos programas de TE quando submetidas a protocolos hormonais que mimetizam o ciclo estral natural. Uma diversidade de protocolos é encontrada na literatura, usando diferentes doses, posologias e intervalos do uso de estradiol associado a progestágenos. Portanto, objetivou-se analisar resultados de pesquisas com protocolos hormonais que poderiam ajudar a solucionar a escassez de receptoras cíclicas e maximizar os resultados da biotécnica de transferência de embriões.(AU)

There are obstacles to the success of equine embryo transfer programs, concomitantly there has been an increase in the popularity of the technique. One of the most urgent issues to overcome is related to the recipient mare availability and the donor-recipient synchrony. Usually, the donor mares have a higher body condition score and are fed a higher quality diet than recipient mares during the non-breeding season. Therefore, the donor mares start cycling earlier than recipient mares, which makes embryo transfer challenging. Several studies have been carried on finding hormonal protocols that mimic the natural oestrous cycle to allow the use of noncycling recipient mares for embryo transfer programs. Many protocols can be found in the literature, using different doses and intervals. Among the main difference is the use of progestogens, which can be used alone or in combination with oestradiol. The aim of this review was to analyse results that could help solve the lack of recipient mares and improve the results of the embryo transfer technique.(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.(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.

Evolução e premissas dos protocolos hormonais de inseminação artificial em tempo fixo na pecuária / Evolution and premises of hormonal protocols of fixed time artificial insemination in livestock

O Brasil historicamente tornou-se um dos principais produtores na pecuária de leite e corte. No entanto, para que o país continue com alta eficácia na produção, deve-se realizar a reposição de animais produtivos. Tal fator é proporcionado pela reprodução animal, através de novas biotecnologias criadas, sendo uma delas a Inseminação Artificial em Tempo Fixo (IATF), a qual atribui um determinado protocolo hormonal e permite saber o dia específico para a inseminação da fêmea, sem a necessidade da observação do estro. O objetivo da atual revisão é sintetizar a evolução dos protocolos hormonais de IATF e apresentar as estratégias atuais para o aumento da fertilidade do rebanho.

Brazil has historically become one of the main producers of dairy and beef cattle. However, for the country to continue with high efficiency in production, it is necessary to perform the replacement productive animals. Such factor is provided by animal reproduction, through new biotechnologies created, one of which is Artificial Insemination in Fixed Time (IATF), which assigns a certain hormonal protocol and it is possible to know the specific day for the insemination of the female without the need of oestrus observation. The objective of the current review is to synthesize the evolution of hormonal protocols of IATF and present the current strategies for increasing herd fertility.

Evolução e premissas dos protocolos hormonais de inseminação artificial em tempo fixo na pecuária / Evolution and premises of hormonal protocols of fixed time artificial insemination in livestock

O Brasil historicamente tornou-se um dos principais produtores na pecuária de leite e corte. No entanto, para que o país continue com alta eficácia na produção, deve-se realizar a reposição de animais produtivos. Tal fator é proporcionado pela reprodução animal, através de novas biotecnologias criadas, sendo uma delas a Inseminação Artificial em Tempo Fixo (IATF), a qual atribui um determinado protocolo hormonal e permite saber o dia específico para a inseminação da fêmea, sem a necessidade da observação do estro. O objetivo da atual revisão é sintetizar a evolução dos protocolos hormonais de IATF e apresentar as estratégias atuais para o aumento da fertilidade do rebanho.(AU)

Brazil has historically become one of the main producers of dairy and beef cattle. However, for the country to continue with high efficiency in production, it is necessary to perform the replacement productive animals. Such factor is provided by animal reproduction, through new biotechnologies created, one of which is Artificial Insemination in Fixed Time (IATF), which assigns a certain hormonal protocol and it is possible to know the specific day for the insemination of the female without the need of oestrus observation. The objective of the current review is to synthesize the evolution of hormonal protocols of IATF and present the current strategies for increasing herd fertility.(AU)

Study of sexual behaviours with different types of estrus synchronization protocols in Boer goats

There is still a lack of information on estrus synchronization in goats. Understanding the estrus synchronization protocols and the subsequent effects is important to improve the efficiency of assisted reproductive technologies (ARTs) and subsequently would improve the breeding procedures. This study will help in determining the most suitable estrus synchronization protocol and understand better the effect on the sexual behaviour and hormonal effects in goats. A total of 127 Boer does were used and divided into three groups with different duration of CIDR insertion intravaginally either for 14 (two groups) or 9 days (one group). Approximately 0.5 ml Estrumate® (PG) was administered intramuscularly to all groups at CIDR removal, and only groups PMSG14 and PMSG9 were administered with 200IU of Pregnant Mare Serum Gonadotropin (PMSG) intramuscularly. Estrus signs were observed at 4 h intervals and blood samples were collected for progesterone and luteinizing hormone determination. The percentage of does in estrus within 24 to 72 h post CIDR removal was significantly higher (P0.05) in all groups. The time of the LH peak in the group without the PMSG was significantly delayed (P

Study of sexual behaviours with different types of estrus synchronization protocols in Boer goats

There is still a lack of information on estrus synchronization in goats. Understanding the estrus synchronization protocols and the subsequent effects is important to improve the efficiency of assisted reproductive technologies (ARTs) and subsequently would improve the breeding procedures. This study will help in determining the most suitable estrus synchronization protocol and understand better the effect on the sexual behaviour and hormonal effects in goats. A total of 127 Boer does were used and divided into three groups with different duration of CIDR insertion intravaginally either for 14 (two groups) or 9 days (one group). Approximately 0.5 ml Estrumate® (PG) was administered intramuscularly to all groups at CIDR removal, and only groups PMSG14 and PMSG9 were administered with 200IU of Pregnant Mare Serum Gonadotropin (PMSG) intramuscularly. Estrus signs were observed at 4 h intervals and blood samples were collected for progesterone and luteinizing hormone determination. The percentage of does in estrus within 24 to 72 h post CIDR removal was significantly higher (P0.05) in all groups. The time of the LH peak in the group without the PMSG was significantly delayed (P(AU)

Influência de alguns fatores sobre o período de gestação no rebanho Girolando da Pesagro (1990-2019) / Influence of some factors on the gestation period in the Girolando Pesagro herd (1990-2019)

O rebanho Girolando tem crescido substancialmente nas últimas décadas no Brasil, tornando a raça uma das mais selecionadas e visadas para a exploração de leite entre os criadores. No entanto, é sabido a importância do manejo das fêmeas para evitar perdas durante a gestação, sendo elevado os abortos e as distocias no periparto, por desconhecimento da previsão de partos. Mas para estabelecer uma tabela de previsão de partos é necessário conhecer o período de gestação de raça explorada. Neste contexto, este estudo envolveu observações de três décadas (1990 a 2019) de avaliação dos efeitos de alguns fatores (ano de parto, sexo da cria, grupo sanguíneo materno, raça paterna e ordem de parto) sobre os períodos de gestação (PG) do rebanho Girolando do Centro Estadual de Pesquisa em Agricultura Orgânica (CEPAO), da Empresa de Pesquisa Agropecuária do Estado do Rio de Janeiro (Pesagro-Rio). Para isso, foram utilizados os dados dos registros do rebanho dos sistemas de fichários e software Gera leite® , relativos aos PG (dia) de vacas Girolando, segundo as variáveis (1) ano, (2) sexo, (3) grupo sanguíneo materno, (4) raça paterno e (5) ordem de parto, tabulados e submetidos a análises descritivas, a anova one-way e teste Bonferroni no software Bioestat. Os métodos reprodutivos utilizados foram as inseminações, realizadas com a observação do estro, seguindo o sistema tradicional de Trimberg e, na última década, também a inseminação artificial em tempo fixo (IATF), com a utilização de protocolos hormonais para sincronização da ovulação. Os resultados médios, da avaliação de 2.104 partos não mostraram diferenças significativas (p>0,05), nos efeitos dos fatores analisados sobre os períodos de gestação. Assim, a média geral de 283,2±6,5 dias, pode ser considerada como uma estimativa dos partos esperados para o rebanho Girolando da Pesagro, a fim de proporcionar manejo e assistência adequados durante o parto, evitando distocias e perdas de mortalidade no periparto.(AU)

The Girolando herd has grown substantially in recent decades in Brazil, making the breed one of the most selected and targeted for milk exploration among breeders. However, it is known the importance of handling females to avoid losses during pregnancy, with abortions and dystocia in the peri-parturition, being high due to the lack of birth prediction. However, to establish a birth prediction table, it is necessary to know the gestation period of the exploited race. In this context, this study involved observations from three decades (1990 to 2019) to assess the effects of some factors (year of birth, sex of offspring, maternal blood group, paternal race and birth order), on gestation periods (PG) of the Girolando herd of the Centro Estadual de Pesquisa Agricultura Orgânica (CEPAO) of Pesagro-Rio. It is located in the municipality of Seropédica, RJ, in the Baixada Fluminense region, where in general the climate presents high temperatures (maximum ± 30oC) and relative air humidity (maximum < 60%). For this, data from the herd records of the binder systems and Gera leite® software were used, related to the PG (day) of Girolando cows, according to (1) year, (2) sex, (3) maternal blood group, (4) paternal race and (5) birth order were tabulated and submitted to descriptive analyzes, the one-way anova and Bonferroni test in the Bioestat software. The reproductive methods used were inseminations, performed with the observation of estrus, following the traditional Trimberg system and, in the last decade, also artificial insemination in fixed time (TAI), with the use of hormonal protocols for synchronization of ovulation). The results of the evaluation did not show significant differences (p>0.05), in the effects of the analyzed factors, on the gestation periods. Thus, the general average of 283.2±6.5 days can be considered as an estimate of expected deliveries for the Pesagro Girolando herd, in order to provide adequate management and assistance during childbirth, avoid dystocias and mortality losses in the peripartum.(AU)

Influência da progesterona injetável na taxa de prenhez e perda gestacional de fêmeas nelore de distintas categorias reprodutivas submetidas a inseminação artificial em tempo fixo / Influence of injectable progesterone on the pregnancy rate and gestational loss of Nellore females of different reproductive categories undergoing fixed-time artificial insemination

Progesterone (P4) is essential for embryonic development and maintenance of pregnancy when deficiency causes early embryonic loss. In this study, we investigated the ability of hormonal supplementation to improve the fertility of Nellore females subjected to fixed-time artificial insemination (IATF) protocols. Here, we evaluated the effect of long-acting injectable progesterone (iP4) supplementation in the D4 after IATF on pregnancy rate and pregnancy loss in Nellore females (Bos taurus indicus) from different reproductive categories in Western Amazonia. Eight hundred thirteen Nellore females from 5 farms were selected and distributed into 2 groups: control [GC; administration of 0.5 mL of 0.9% saline solution, intramuscularly - IM] (n = 407) and a group that received injectable progesterone (iP4) that was long-acting [GiP4; administration of 0.5 mL of iP4, 300 mg, via IM four days after IATF] (n = 406). Each group contained 3 subgroups: heifers, primiparous cows, and multiparous cows. Of the 407 animals in the CG, 103 were heifers, 107 primiparous, and 197 multiparous. Of the 406 animals in the GiP4 group, there were 101 heifers, 107 primiparous, and 198 multiparous. On a random day of the estrous cycle (D0), an intravaginal device containing 1 g of P4 and 2 mg of estradiol benzoate (BE) was inserted by intramuscular injection. On D8, the P4 device was removed and 150 µg of D-cloprostenol (PGF2α), 300 IU eCG, and 1 mg BE were administered IM. Cows were inseminated at D10, 48-52 h after procedure on D8. Pregnancy diagnosis was made between 35 and 40 days after insemination through ultrasound examination. Between 80 and 90 days after insemination, a new ultrasound examination was performed to assess early pregnancy loss. The data were processed using the SAS 9.2. The conception rate, pregnancy loss, and final conception rate were analyzed using PROC GLIMMIX according to groups (CG and GiP4), categories (heifers, primiparous and multiparous), and their interactions as variables. The differences in the means of least squares were adjusted using the Tukey­Kramer method. Statistical significance was defined as P < 0.05. The general conception rate was 46% (375/816). Regardless of the animal class, GiP4 animals (51.97%) had higher conception rates (P < 0.05) than CG (40.29%). In the subgroups (heifers, primiparous and multiparous cows), there was a difference (P < 0.05) between animals treated with iP4 (52.48%, 57.94%, and 48.48%, respectively) and those who were not (39.81%, 41.12%, and 40.10%, respectively). Gestational losses, regardless of the animal class, were higher in females in the CG (7.93%) [P < 0.05] compared to those in the GiP4 group (2.84%). Regardless of treatment with iP4, the percentage of gestational loss in heifers was significantly higher (10.64%) than that in primiparous and multiparous cows (3.77% and 2.86%, respectively). The final conception rates were higher in animals that received long-acting iP4, which increased the final pregnancy in all parity categories. In the present study, the use of iP4 increased the pregnancy rate in Nellore females, regardless of the category. Although there has been no consensus on the use of iP4, there is an agreement that increases in the pregnancy rate are related to the moment of exogenous P4 application. In addition to influencing the pregnancy rate, reduction in pregnancy losses is also attributed to iP4 treatment, a fact demonstrated in the present study, where animals treated with iP4 had a lower pregnancy loss rate than normally occurs in beef cattle. Supplementation with long-acting iP4 increased the pregnancy rate at D35-40, reduced pregnancy losses, and increased the conception rate on D80-90 days in Nellore females reared in the Western Amazon, regardless of the animal category.(AU)

Efeito de protocolo hormonal e programa de luz artificial na gestação de éguas receptoras de embrião durante o período de transição de primavera / Effect of hormonal protocol and artificial light program on the pregnancy of embryo recipient mares during spring transition period

O objetivo do estudo foi comparar o efeito das técnicas hormonais e de luz artificial nas éguas receptoras de embrião acíclicas avaliando as taxas de gestação aos 14 e 28 dias durante a fase de transição de primavera. Os 48 animais foram distribuídos aleatoriamente nos grupos: controle (CONT, n=16), éguas cíclicas na fase ovulatória; luz artificial (LUZ, n=16), éguas acíclicas submetidas ao tratamento de luz artificial; e hormônio (HORM, n= 16), éguas acíclicas submetidas ao protocolo hormonal na fase de transição. As éguas do grupo LUZ foram estimuladas por 60 dias com luz artificial durante cinco horas por dia. Nos grupos CONT e LUZ, quando observada a presença de folículo 35 mm de diâmetro e edema uterino grau II, foram administrados 1,5 mg de acetato de deslorelina e 1500 UI de hCG para induzir a ovulação. As éguas do grupo HORM foram tratadas com três doses de 1,5 mg de benzoato de estradiol e seguiram os mesmos protocolos dos Grupos CONT e LUZ. Foi avaliada a taxa de gestação por ultrassonografia aos 14 dias e confirmação aos 28 em todos os grupos experimentais. Foi realizada análise descritiva e teste Qui-quadrado (significância de 5%). Taxas de gestação aos 14 e 28 dias foram semelhantes (p>0,05) entre todos os grupos. Os tratamentos HORM e LUZ durante o período de transição inverno-primavera mostraram-se eficazes para atender ao programa de transferência de embr

The aim of this study was to compare the effect of hormonal and artificial light techniques on acyclic embryo recipient mares by assessing pregnancy rates at 14 and 28 days during the spring transition period. The 48 animals were randomly assigned to the groups: control (CONT, n = 16), cyclic mares in the ovulatory phase; artificial light (LIGHT, n = 16), acyclic mares subjected to artificial light treatment; and hormone (HORM, n = 16), acyclic mares submitted to hormonal protocol in transition phase. In the LIGHT group, mares were stimulated with artificial light for five hours a day, for 60 days. In CONT and LIGHT groups, when a follicle ≥ 35 mm in diameter and uterine edema ≥ grade II were observed, 1.5 mg of deslorelin acetate and 1500 IU hCG were administered to induce ovulation. In the HORM group, mares were treated with three doses of 1.5 mg of estradiol benzoate and followed the same protocols as the CONT and LIGHT groups. Pregnancy rate was assessed by ultrasound at 14 days and confirmation at 28 days in all experimental groups. Descriptive analysis and chi-square test (5% significance) were performed. Pregnancy rates at 14 and 28 days were similar (p> 0.05) among all groups. The HORM and LIGHT treatments during the winter-spring transition period proved to be effective during the embryo transfer programs. As it is a more natural method, the LIGHT protocol has the potential to be one more biotechnological tool in equine reproduction.(AU)

Efeito de protocolo hormonal e programa de luz artificial na gestação de éguas receptoras de embrião durante o período de transição de primavera / Effect of hormonal protocol and artificial light program on the pregnancy of embryo recipient mares during spring transition period

O objetivo do estudo foi comparar o efeito das técnicas hormonais e de luz artificial nas éguas receptoras de embrião acíclicas avaliando as taxas de gestação aos 14 e 28 dias durante a fase de transição de primavera. Os 48 animais foram distribuídos aleatoriamente nos grupos: controle (CONT, n=16), éguas cíclicas na fase ovulatória; luz artificial (LUZ, n=16), éguas acíclicas submetidas ao tratamento de luz artificial; e hormônio (HORM, n= 16), éguas acíclicas submetidas ao protocolo hormonal na fase de transição. As éguas do grupo LUZ foram estimuladas por 60 dias com luz artificial durante cinco horas por dia. Nos grupos CONT e LUZ, quando observada a presença de folículo 35 mm de diâmetro e edema uterino grau II, foram administrados 1,5 mg de acetato de deslorelina e 1500 UI de hCG para induzir a ovulação. As éguas do grupo HORM foram tratadas com três doses de 1,5 mg de benzoato de estradiol e seguiram os mesmos protocolos dos Grupos CONT e LUZ. Foi avaliada a taxa de gestação por ultrassonografia aos 14 dias e confirmação aos 28 em todos os grupos experimentais. Foi realizada análise descritiva e teste Qui-quadrado (significância de 5%). Taxas de gestação aos 14 e 28 dias foram semelhantes (p>0,05) entre todos os grupos. Os tratamentos HORM e LUZ durante o período de transição inverno-primavera mostraram-se eficazes para atender ao programa de transferência de embr

The aim of this study was to compare the effect of hormonal and artificial light techniques on acyclic embryo recipient mares by assessing pregnancy rates at 14 and 28 days during the spring transition period. The 48 animals were randomly assigned to the groups: control (CONT, n = 16), cyclic mares in the ovulatory phase; artificial light (LIGHT, n = 16), acyclic mares subjected to artificial light treatment; and hormone (HORM, n = 16), acyclic mares submitted to hormonal protocol in transition phase. In the LIGHT group, mares were stimulated with artificial light for five hours a day, for 60 days. In CONT and LIGHT groups, when a follicle ≥ 35 mm in diameter and uterine edema ≥ grade II were observed, 1.5 mg of deslorelin acetate and 1500 IU hCG were administered to induce ovulation. In the HORM group, mares were treated with three doses of 1.5 mg of estradiol benzoate and followed the same protocols as the CONT and LIGHT groups. Pregnancy rate was assessed by ultrasound at 14 days and confirmation at 28 days in all experimental groups. Descriptive analysis and chi-square test (5% significance) were performed. Pregnancy rates at 14 and 28 days were similar (p> 0.05) among all groups. The HORM and LIGHT treatments during the winter-spring transition period proved to be effective during the embryo transfer programs. As it is a more natural method, the LIGHT protocol has the potential to be one more biotechnological tool in equine reproduction.

Relationship between Body Mass Index (BMI) and testicular and hormonal parameters of sexually active male greater cane rats (Thryonomys swinderianus)

The current upsurge in intensive farming practices of greater cane rat has not only lead to higher growth rate but is accompanied by increased fat deposition especially in the males. This study attempts to characterize one of the most commonly used fat estimation parameter, the body mass index (BMI) as well as evaluates its relationship with testicular and hormonal parameters in seventy-two sexually active male cane rats over a period of one year. Six animals, kidded and raised in a farm, with known ages were used each month. The experimental protocols entail body measurements of weight, height and length; histology; orchidometry; and hormonal immunoassay of testosterone, estradiol, progesterone, LH and FSH using their various kits. The mean values of the body mass (BMI) and Lee (LI) indices of male greater cane rats were 1.18±0.20g/cm2 and 0.30±0.02g/cm respectively with the testicular histology indicating normal spermatogenesis. BMI/LI, both of which followed the same pattern, neither correlate with testicular parameters nor with serum testosterone, progesterone, LH and FSH concentrations but had low correlations with serum estradiol concentration (r2 = 0. 2; p = 0.0023). So, these relationships may provide clue on obesity and its effect on reproductive performance and strengthened the possibility of the characterized BMI/LI as obesity marker for breeding selection in male cane rat.

Relationship between Body Mass Index (BMI) and testicular and hormonal parameters of sexually active male greater cane rats (Thryonomys swinderianus)

The current upsurge in intensive farming practices of greater cane rat has not only lead to higher growth rate but is accompanied by increased fat deposition especially in the males. This study attempts to characterize one of the most commonly used fat estimation parameter, the body mass index (BMI) as well as evaluates its relationship with testicular and hormonal parameters in seventy-two sexually active male cane rats over a period of one year. Six animals, kidded and raised in a farm, with known ages were used each month. The experimental protocols entail body measurements of weight, height and length; histology; orchidometry; and hormonal immunoassay of testosterone, estradiol, progesterone, LH and FSH using their various kits. The mean values of the body mass (BMI) and Lee (LI) indices of male greater cane rats were 1.18±0.20g/cm2 and 0.30±0.02g/cm respectively with the testicular histology indicating normal spermatogenesis. BMI/LI, both of which followed the same pattern, neither correlate with testicular parameters nor with serum testosterone, progesterone, LH and FSH concentrations but had low correlations with serum estradiol concentration (r2 = 0. 2; p = 0.0023). So, these relationships may provide clue on obesity and its effect on reproductive performance and strengthened the possibility of the characterized BMI/LI as obesity marker for breeding selection in male cane rat.(AU)

Hormonal protocols for the synchronization and induction of synchronized estrus in dairy ewes kept under tropical conditions

Background: Lacaune is an important sheep breed and shows reproductive seasonality which affects dairy product supply. The most common hormonal protocols are based on progesterone-releasing devices in order to reach reproductive activity. Due to international consumer demand for natural, green, and clean methods, such issues encourage the minimal or absent use of synthetic hormones in livestock. In this sense, the present study tested the efficiency of induction and estrus synchronization protocols in lacaune ewes, considering: application interval of synthetic prostaglandin at the breeding season; length of synthetic progesterone exposure; and eCG dose at the outbreeding season. Materials, Methods & Results: In study 1: 52 ewes were submitted to estrus synchronization protocol using two doses of d-cloprostenol 7 or 9 days apart. In study 2: 47 ewes were submitted to estrus induction protocol using an intravaginal device containing 60 mg of medroxyprogesterone acetate maintained for 6, 9, or 12 days. In study 3: 46 ewes were submitted to synchronized estrus induction protocol using intravaginal progesterone device for six days. On the fifth day, d-cloprostenol and 300 IU or 400 IU of eCG were administered. For all studies, signs of estrus beginning/ending were recorded and natural mating was performed. After 30 days, transrectal ultrasound was performed for pregnancy diagnosis. In study 1, groups presented similar rate of estrus behavior (78.8%) and pregnancy (average 75.6%). Meanwhile, compared to G9days (37.8 ± 7.2 h), interval between the second dose of prostaglandin and beginning of estrus was smaller in G7days (31.5 ± 7.8 h). No difference was found among variables studied in study 2 (P > 0.05), nevertheless the SD for the estrus duration was shorter (P < 0.05) in G6days and G12 days when compared with the G9days . Equally, the SD...

Wild Leporinus friderici induced spawning with different dose of mGnRHa and metoclopramide or carp pituitary extract

Breeding technology is of utmost importance for reproduction of wild fish in captivity for the reintroduction and selective breeding programs purposes. The main challenge is that when applied to wild undomesticated specimens, conventional protocols often cause breeders and/or embryo mortality and spawning failure. In this study, we evaluated the reproductive performance of wild Leporinus friderici, a great importance fish for subsistence fishing in South American rivers, applying conventional and lower-dose hormonal therapies by means of two consecutive experiments. In the first, a conventional (0.5 and 5.5 mg/kg) and a lower carp pituitary extract (CPE) dose (0.5 and 1.0 mg/kg) were applied. In the second, a conventional mammalian GnRH analogue associated with metoclopramide (mGnRHa + MET) (40 µg mGnRHa + 20 mg MET/kg) and a lower dose (4 μg mGnRHa + 2 mg MET/kg and 8 µg + 4 mg of mGnRHa + MET/kg) were applied. Ovulation was observed in all treatments, however, only lower CPE protocol provided viable embryos. High levels of 17α,20β-dihydroxy-4-pregnen-3-one (DHP) and 17β estradiol (E2) detected in conventional, but not in lower CPE dose, at ovulation, might be associated to the mortality of the embryos. The use of lower CPE dose applied here was the best way to obtain L. friderici viable embryos. These results directly contribute to the knowledge about poorly explored effects of reproductive management and hormonal therapies in wild-type breeders, showing that the use of reduced doses may be an alternative to reproductive success.