Bovine somatotropin increases the pregnancy rate in fixed-time artificial insemination in beef cattle.

This study evaluated the effect of bovine somatotropin (bST) on pregnancy rate (PR) and size of the dominant follicle (DF) on the day of intravaginal progesterone (P4) removal in protocols for fixed-time artificial insemination (FTAI). Bos indicus (Nellore) females (n = 392) were distributed into three groups. The control group (CG; n = 92) received an intravaginal P4 device + estradiol benzoate on day (d)0; prostaglandin F2α on d7 (first application); removal of P4 + estradiol cypionate (EC) + PGF2α (second application) + ultrasound (US) of the DF on d9; the FTAI was performed on d11; and pregnancy diagnosis (PD) was performed on d45. The bST group (bSTG; n = 142) underwent the same protocol as the CG, except that the animals received 125 mg of bST on d7. The equine chorionic gonadotropin (eCG) group (eCGG; n = 158) underwent the same protocol as the CG, except that the animals received 300 IU of eCG on d9. The PRs of the bSTG, eCGG, and CG were 48%, 48%, and 35%, respectively (p < .05); the bSTG and eCGG showed greater PRs, with follicles 6-7.9 mm (p < .05) and 8-8.9 mm in diameter, respectively. The bSTG exhibited a greater dimension of the DF on d9 of the protocol (p < .05). The eCGG had higher PRs with a body condition score (BCS) of 2.5, and the bSTG had a BCS of 3.0 (p < .05). It was concluded that bST increased PR, bST showed better performance in smaller DF and larger follicular diameter on d9 of the protocol, eCG acted better on animals with lower BCSs, and bST can be used in FTAI.

Effect of recombinant bovine somatotropin on the reproductive efficiency of beef cows subjected to differently timed-artificial insemination protocols.

This study aimed to verify the reproductive efficiency of beef cows treated with recombinant bovine somatotropin (rbST). Study 1, Bos indicus cows were distributed (three groups). The control group (CG) was subjected: on day zero (d0), the animals received a CIDR and oestradiol benzoate (EB); on (d8, CIDR was removed, and PGF2α and oestradiol cypionate (EC) were administered; on d10, timed Artificial Insemination (TAI) was performed; on d45, pregnancy diagnosis was made. The rbST on d0 group (bST0G) was subjected to an identical protocol as CG, except for the addition of 250 mg rbST on d0. The rbST on d8 group (bST8G) was subjected to the same protocol as bST0G, except that the rbST was administered on d8 rather. In study 2, the animals followed the same design which was used in Bos taurus cows. The follicular growth rate (FGR) was calculated between d8 and d10. In study 1, pregnancy/artificial insemination (P/AI) did not differ among the treatments. FGR in bST8G was higher than in other groups. In study 2, bST0G showed higher Pregnancy/Artificial Insemination (P/AI) (p < .05) when compared with other groups. bST0G showed a different FGR (p < .0001) than the other groups. In conclusion, rbST (Bos indicus cows) did not increase P/AI, but it did promote follicular growth when administered on d8; the rbST administered on d0 improved P/AI (p < .05) and the FGR in Bos taurus cows.

Assisted Reproductive Technologies (ART) and genome editing to support a sustainable livestock.

This article provides an overview of assisted reproductive technologies (ART) and genome engineering to improve livestock production systems for the contribution of global sustainability. Most ruminant production systems are conducted on grassland conditions, as is the case of South American countries that are leaders in meat and milk production worldwide with a well-established grass-feed livestock. These systems have many strengths from an environmental perspective and consumer preferences but requires certain improvements to enhance resource efficiency. Reproductive performance is one of the main challenges particularly in cow-calf operations that usually are conducted under adverse conditions and thus ART can make a great contribution. Fixed-time artificial insemination is applied in South America in large scale programs as 20 to 30% of cows receive this technology every year in each country, with greater calving rate and significant herd genetic gain occurred in this region. Sexed semen has also been increasingly implemented, enhancing resource efficiency by a) obtaining desired female replacement and improving animal welfare by avoiding newborn male sacrifice in dairy industry, or b) alternatively producing male calves for beef industry. In vitro embryo production has been massively applied, with this region showing the greatest number of embryos produced worldwide leading to significant improvement in herd genetics and productivity. Although the contribution of these technologies is considerable, further improvements will be required for a significant livestock transformation and novel biotechnologies such as genome editing are already available. Through the CRISPR/Cas-based system it is possible to enhance food yield and quality, avoid animal welfare concerns, overcome animal health threats, and control pests and invasive species harming food production. In summary, a significant enhancement in livestock productivity and resource efficiency can be made through reproductive technologies and genome editing, improving at the same time profitability for farmers, and global food security and sustainability.

Assisted Reproductive Technologies (ART) and genome editing to support a sustainable livestock

This article provides an overview of assisted reproductive technologies (ART) and genome engineering to improve livestock production systems for the contribution of global sustainability. Most ruminant production systems are conducted on grassland conditions, as is the case of South American countries that are leaders in meat and milk production worldwide with a well-established grass-feed livestock. These systems have many strengths from an environmental perspective and consumer preferences but requires certain improvements to enhance resource efficiency. Reproductive performance is one of the main challenges particularly in cow-calf operations that usually are conducted under adverse conditions and thus ART can make a great contribution. Fixed-time artificial insemination is applied in South America in large scale programs as 20 to 30% of cows receive this technology every year in each country, with greater calving rate and significant herd genetic gain occurred in this region. Sexed semen has also been increasingly implemented, enhancing resource efficiency by a) obtaining desired female replacement and improving animal welfare by avoiding newborn male sacrifice in dairy industry, or b) alternatively producing male calves for beef industry. In vitro embryo production has been massively applied, with this region showing the greatest number of embryos produced worldwide leading to significant improvement in herd genetics and productivity. Although the contribution of these technologies is considerable, further improvements will be required for a significant livestock transformation and novel biotechnologies such as genome editing are already available. Through the CRISPR/Cas-based system it is possible to enhance food yield and quality, avoid animal welfare concerns, overcome animal health threats, and control pests and invasive species harming food production. In summary, a significant enhancement in livestock productivity and resource efficiency can be made through reproductive technologies and genome editing, improving at the same time profitability for farmers, and global food security and sustainability.(AU)

Criopreservação do sêmen suíno: desafios a serem superados que auxiliam a identificação de espermatozoides mais férteis / Boar semen cryopreservation: challenges to be overcome that help the identification of more fertile spermatozoa

A criopreservação é o melhor método de armazenamento de sêmen por período indeterminado, conferindo alta flexibilidade de uso. Além disso, é o principal meio para formação de banco de germoplasma. No entanto, congelar sêmen suíno ainda é um desafio a ser enfrentado. Isso porquê, além das características de membrana espermática que ocasionam maiores efeitos deletérios às células durante os processos de congelação e descongelação, ainda é preciso lidar com a grande variabilidade de resultados, seja entre indivíduos, ejaculados de um mesmo indivíduo ou ainda, frações de um mesmo ejaculado. Frente a isso, diferentes estratégias têm sido investigadas a fim de obter melhores resultados e assim, aumentar a aplicabilidade do sêmen congelado suíno a nível comercial. Além disso, acreditamos que haja a possibilidade de se relacionar a capacidade de criotolerância de um determinado espermatozoide a sua maior ou menor capacidade de fertilizar o oócito.(AU)

Cryopreservation is the best method of storing semen indefinitely, providing high flexibility of use. In addition, it is the primary means for forming a germplasm bank. However, freezing boar semen is still a challenge to be faced because, in addition to the characteristics of the spermatic membrane that cause deleterious effects to the cells during the freezing and thawing processes, it is still necessary to deal with the significant variability of results, whether between individuals, ejaculates from the same individual or even fractions of an even ejaculated. Because of this, different strategies have been investigated to obtain better results and thus increase the applicability of frozen boar semen at a commercial level. Furthermore, we believe it is possible to relate the cryotolerance capacity of a given sperm to its greater or lesser capacity to fertilize the oocyte.(AU)

Relação entre a capacitação espermática e a fertilidade de sêmen criopreservado de bovinos / Relationship between sperm capacitation and fertility in bovine cryopreserved semen

A qualidade do sêmen criopreservado, utilizado na inseminação artificial em tempo fixo (IATF) em bovinos, é um dos principais fatores que impactam sobre a fertilidade, e está relacionada à capacidade de produção espermática dos touros, à criotolerância dos espermatozoides e aos critérios técnicos do processo de criopreservação adotados. Neste sentido, devemos destacar a importância do controle de qualidade das partidas de sêmen antes de serem liberadas para uso na IATF. Nos últimos anos várias técnicas vêm sendo desenvolvidas para avaliar com mais acurácia as partidas de sêmen e evitar o uso daquelas que possam resultar em prejuízos na fertilidade, mas mesmo assim, tem se notado alta variabilidade na taxa de prenhez entre touros e entre partidas de sêmen. Esta divergência se deve ao fato da habilidade fértil do espermatozoide ser multifatorial, ou seja, dependente de diversas características estruturais, morfofuncionais e moleculares. Ademais, os eventos que permitem os espermatozoides passarem por capacitação espermática, um pré-requisito para a fertilidade, têm intrigado os pesquisadores em vista da complexidade dos processos envolvidos e dos efeitos deletérios da criopreservação espermática. Esta revisão tem por objetivo compilar estudos que mostrem a relação entre a capacitação espermática e a fertilidade do sêmen bovino criopreservado, levando em consideração as técnicas de avaliação e os resultados até o momento.(AU)

The quality of cryopreserved semen, used in fixed-time artificial insemination (FTAI) in cattle, is one of the main factors that impact fertility and is related to the sperm production capacity of bulls, sperm cryotolerance, and the technical criteria for cryopreservation. In this sense, we must highlight the importance of quality control of semen batches before commercialization for the FTAI. In recent years, several techniques have progressed to more accurately evaluate semen batches and avoid using those that may result in impaired fertility. However, we still notice a high variability in the pregnancy rate between bulls and between semen batches. This divergence is due to the multifactorial sperm-fertilizing ability, i.e., it depends on several structural, morphofunctional, and molecular characteristics. In addition, the events that allow sperm to undergo sperm capacitation, a prerequisite for fertility, have intrigued researchers due to the complexity of the processes involved and the adverse effects of sperm cryopreservation. This review aims to compile studies that show the relationship between sperm capacitation and fertility in cryopreserved bovine semen, considering the evaluation techniques and results to date.(AU)

Application of PGF2α at the moment of fixed-time artificial insemination in crossbred beef cows.

Although studies have shown positive effects of gonadotropin releasing hormone (GnRH) or prostaglandin F2α (PGF2α) at the moment of fixed-time artificial insemination (FTAI) in the conception rate (CR) of cattle, its effects on treatments based on progesterone (P4) and estradiol benzoate (EB) is still not conclusive. The objective of this study was (1) to evaluate the effect of a PGF2α analogue at FTAI in the CR of crossbred beef cows submitted to a 11d FTAI protocol based on P4 and EB; and (2) to describe the CR between PGF2α-treated and control cows in different body condition scores (BCS) and parity categories. Crossbred (½ Nellore and ½ Angus) beef cows were submitted to a synchronization protocol and randomly assigned into 2 groups: Control (n = 163), at FTAI cows received 2 mL of saline solution as a placebo, and PGF2α (n = 163), at FTAI cows were treated with PGF2α analogue (10 mg of dinoprost tromethamine). Pregnancy diagnosis was performed 33d post-FTAI. Binary logistic regression model was used to analyze the effect of PGF2α treatment on CR. There was no difference in CR between PGF2α and control groups (P > 0.05; odds ratio (OR) = 0.92; confidence interval (CI) = 0.59-1.4). A greater CR was found in heifers (P = 0.0006, OR = 2.65, CI = 1.61 - 4.38) and multiparous (P = 0.0006, OR = 2.12, CI = 1.04 - 4.3) when compared to primiparous cows. Cows with low BCS (4; 9-point scale) showed lower CR when compared with moderate BCS (5-6; 9-point scale) (P < 0.05; OR = 0.10; CI = 0.06 - 0.18). There was no numerical difference on CR between PGF2α-treated and control cows in different BCS and parity categories. The results suggested that the CR in this study was not influenced by 10 mg PGF2α analogue at FTAI.

Prepartum and/or postpartum supplementation with monensin-molasses multinutrient blocks to optimize fertility and calf performance in primiparous beef cows.

OBJECTIVE: Pregnant Nelore heifers (n = 417) were used to evaluate the effects of supplementation with monensin-molasses multinutrient block (B) during pre and/or postpartum on reproductive and progeny performance. METHODS: Heifers were allocated in four treatments: i) CC: heifers received control supplement (C) in loose meal form (0.06% of body weight [BW] offered daily before and after parturition; n = 108); ii) CB: received C before parturition and B (0.07% of BW offered weekly after parturition; n = 117); iii) BC: received B before and C after parturition (n = 103) and iv) BB: received B before and after parturition (n = 89). During pre and postpartum periods, concentration of metabolites/hormones and cow/calf performance was evaluated over time. Cows were synchronized twice for fixed timed artificial insemination (FTAI) using an estradiol/progesterone-based protocol. Data was analyzed by orthogonal contrasts (C). RESULTS: B increased pregnancy at first FTAI (p = 0.04) and overall pregnancy rate (C1: CC vs BB+BC+CB; p = 0.05). Supplemented cows had greater body condition score (BCS) only at parturition (D0; p = 0.04) and at D40 (p = 0.02). B increased BW (p = 0.03), glucose concentrations (p = 0.01) and subcutaneous fat thickness (p = 0.03) only at D40. Concentrations of insulin were higher in supplemented cows (p = 0.008). Calves born by cows supplemented before and after parturition (C2: BB vs BC+CB) were heavier at 80 (p<0.001), 120 (p<0.001), 170 (p = 0.002) and 210 (p = 0.02) days old. CONCLUSION: Regardless of period of treatment, block supplementation increased pregnancy at first FTAI and overall pregnancy rate. Additionality, block supplementation during both pre and postpartum periods improved progeny weight until weaning. Block supplementation can be a tool to optimize fertility and calf performance in Nelore primiparous cows.

Impacto da qualidade de sêmen sobre os resultados da IATF / Impact of sperm quality on IATF results

O Brasil vive um cenário de grande demanda pelo produto carne, tanto para o mercado interno quanto para o mercado externo. Para atender a esta demanda, há o envolvimento de toda a cadeia da carne, desde os programas de melhoramento genético com o fornecimento de touros melhoradores para tais características, como as centrais de colheita de sêmen desses animais para uso em massa por meio da Inseminação Artificial em Tempo Fixo (IATF). Para que haja sucesso no uso desta biotécnica, é de vital importância a qualidade do produto sêmen aliado às outras características como ambiência e nutrição.(AU)

Brazil is now with a great demand of beef products, for the domestic and exportation markets. To delivery the demand, the entire meat chain must be involved, included genetics programs to provide and separate superior bulls, and the collection centers that collect this superior genetics bulls to be used in the Fixed Timed Artificial Insemination (FTAI) biotechnique in a large scale. In order to be successful using this biotechnology, the quality of the semen combined with other characteristics such as ambience and nutrition are extremely important.(AU)

Application of PGF2α at the moment of fixed-time artificial insemination in crossbred beef cows

Although studies have shown positive effects of gonadotropin releasing hormone (GnRH) or prostaglandin F2α (PGF2α) at the moment of fixed-time artificial insemination (FTAI) in the conception rate (CR) of cattle, its effects on treatments based on progesterone (P4) and estradiol benzoate (EB) is still not conclusive. The objective of this study was (1) to evaluate the effect of a PGF2α analogue at FTAI in the CR of crossbred beef cows submitted to a 11d FTAI protocol based on P4 and EB; and (2) to describe the CR between PGF2α-treated and control cows in different body condition scores (BCS) and parity categories. Crossbred (½ Nellore and ½ Angus) beef cows were submitted to a synchronization protocol and randomly assigned into 2 groups: Control (n = 163), at FTAI cows received 2 mL of saline solution as a placebo, and PGF2α (n = 163), at FTAI cows were treated with PGF2α analogue (10 mg of dinoprost tromethamine). Pregnancy diagnosis was performed 33d post-FTAI. Binary logistic regression model was used to analyze the effect of PGF2α treatment on CR. There was no difference in CR between PGF2α and control groups (P > 0.05; odds ratio (OR) = 0.92; confidence interval (CI) = 0.59-1.4). A greater CR was found in heifers (P = 0.0006, OR = 2.65, CI = 1.61 - 4.38) and multiparous (P = 0.0006, OR = 2.12, CI = 1.04 - 4.3) when compared to primiparous cows. Cows with low BCS (4; 9-point scale) showed lower CR when compared with moderate BCS (5-6; 9-point scale) (P < 0.05; OR = 0.10; CI = 0.06 - 0.18). There was no numerical difference on CR between PGF2α-treated and control cows in different BCS and parity categories. The results suggested that the CR in this study was not influenced by 10 mg PGF2α analogue at FTAI.(AU)

Retirada de corpo estranho (dispositivo impregnado com progesterona) da cavidade abdominal de novilha da raça Jersey ­ relato de caso / Removal of a foreign body (progesterone impregnated device) from the abdominal cavity of a Jersey heifer ­ a case report / Extracción de cuerpo extraño (dispositivo impregnado con progesterona) de la cavidad abdominal de novilla raza Jersey - reporte de caso

A inseminação artificial em tempo fixo (IATF) é uma biotécnica com inúmeras vantagens para a produção de bovinos. Para a realização da IATF, as fêmeas bovinas devem receber um protocolo farmacológico que induz a ovulação de forma sincronizada. Esse protocolo inicia com a inserção de um dispositivo impregnado com progesterona que deve permanecer no fundo vaginal da fêmea por tempo determinado. O presente relato tem por objetivo descrever a remoção de um implante impregnado com progesterona que foi encontrado na cavidade abdominal de uma novilha. Durante um atendimento reprodutivo de rotina em uma propriedade rural, uma novilha da raça Jersey, recém-adquirida, com histórico de ter sido submetida à IATF, foi avaliada para diagnóstico de gestação. No exame a novilha não estava gestante e apresentava um cisto folicular ovariano. A novilha foi submetida novamente à IATF em que foi inserido e removido um implante, com isso o cisto regrediu e ao inseminar a novilha não foi possível passar a cérvix com o aplicador. Vinte dias após a inseminação a novilha manifestou estro e ao ser avaliada para nova inseminação, foi identificado um implante solto na cavidade abdominal da novilha. Foi realizada uma laparotomia pelo flanco esquerdo e o implante foi removido. Após a recuperação da cirurgia a novilha foi inseminada e novamente e ficou gestante. Os protocolos de IATF devem ser realizados por profissionais capacitados para evitar problemas como a presente situação em que um implante foi encontrado na cavidade abdominal de uma novilha.(AU)

The fixed-time artificial insemination (FTAI) is a biotechnique with numerous advantages for cattle production. In order to perform the FTAI, the cows must receive a pharmacological protocol to induce ovulation in a synchronized way. This protocol begins with the insertion of a device impregnated with progesterone that must remain in the vaginal fundus of the cow for a specific period of time. This report aims at describing the removal of a progesterone impregnated implant that was found in the abdominal cavity of a heifer. During a routine reproductive service in a rural property, a recently acquired Jersey heifer, with history of having been submitted to FTAI, was evaluated for pregnancy diagnosis. At the exam, it was observed that the heifer was not pregnant and presented an ovarian follicular cyst. The heifer was then submitted to FTAI again, where an implant was inserted and removed. This made the cyst to recede, and upon subsequent insemination, the applicator was not able to pass the cervix. Twenty days after insemination, the heifer was in estrus and when it was evaluated for insemination, a loose implant was identified in the abdominal cavity of the heifer. A laparotomy was performed through the left flank and the implant was removed. After recovery from the surgery, the heifer was inseminated again and became pregnant. The FTAI protocols should only be carried out by trained professionals to avoid problems such as the one presented herein, where an implant was found in the abdominal cavity of a heifer.(AU)

La inseminación artificial a tiempo fijo (FTAI) es una biotécnica con numerosas ventajas para la producción de ganado. Para realizar FTAI, las hembras bovinas deben recibir un protocolo farmacológico que induzca la ovulación de forma sincronizada. Este protocolo comienza con la inserción de un dispositivo impregnado con progesterona que debe permanecer en el fondo vaginal de la hembra durante un tiempo específico. Este informe tiene como objetivo describir la extracción de un implante impregnado de progesterona que se encontró en la cavidad abdominal de una novilla. Durante la atención reproductiva de rutina en una propiedad rural, se evaluó el diagnóstico de preñez de una novilla de Jersey recién adquirida con antecedentes de someterse a FTAI. En el examen, la novilla no estaba embarazada y tenía un quiste folicular ovárico. La novilla fue nuevamente sometida a FTAI, en la cual se insertó y removió un implante, con esto el quiste retrocedió y al inseminar a la novilla no fue posible pasar el cérvix con el aplicador. Veinte días después de la inseminación, la vaquilla manifestó estro y cuando se evaluó para una nueva inseminación, se identificó un implante suelto en la cavidad abdominal de la vaquilla. Se realizó una laparotomía a través del flanco izquierdo y se extrajo el implante. Después de recuperarse de la cirugía, la novilla fue inseminada y nuevamente quedó embarazada. Los protocolos FTAI deben ser realizados por profesionales capacitados para evitar problemas como la situación actual donde se encontró un implante en la cavidad abdominal de una novilla.(AU)

Luteogenesis and Embryo Implantation Are Enhanced by Exogenous hCG in Goats Subjected to an Out-of-Season Fixed-Time Artificial Insemination Protocol.

The aim of this study was to evaluate the possible effect of two doses of hCG (100 and 300 IU) applied at two different times (7 and 14 d) after a fixed-time artificial insemination protocol (FTAI) upon some variables involved in the embryonic implantation rate in goats during the natural deep anestrous season (April, 25° north). The experimental units considered crossbred, multiparous, anovulatory goats (n = 69, Alpine, Saanen, Nubian x Criollo), with average body weight (43.6 ± 5.7 kg) and body condition score (1.86 ± 0.28 units) located in northern-semiarid Mexico (25° N, 103° W). Once the goat's anestrus status was confirmed, goats were subjected to an estrus induction protocol. Upon estrus induction confirmation, goats (n = 61) were subjected to a FTAI procedure. Immediately after the FTAI, the goats were randomly distributed to five experimental groups: (1). G100-7 (n = 13) 100 IU, hCG 7 d post-FTAI, (2). G100-14 (n = 12) 100 IU hCG, 14 d post-FTAI, (3). G300-7 (n = 12) 300 IU, hCG, 7 d post-FTAI, (4). G300-14 (n = 12) 300 IU hCG 14 d post-FTAI, and (5). Control group, CONT (n = 12) 0.5 mL saline, 7 and 14 d post-FTAI. The response variables conception rate (39.36 ± 0.23), fertility rate (27.96%), prolificacy rate (1.1 ± 0.29 kids), ovulation rate (0.74 ± 0.20 corpus luteum) corpus luteum diameter (10.15 ± 0.59 mm), embryo number (1.58 ± 0.20), and embryo implantation rate (48.96%), did not differ between treatments. However, while the variables fecundity rate (67%), embryo efficiency index-1 (33.99 ± 0.20%), and embryo efficiency index-2 (27.94 ± 0.30%) were favored by the G300-14 treatment, the corpus luteum area was favored (p < 0.05) by both G300-7 (113.30 ± 0.19 mm2) and G300-14 (103.04 ± 0.17 mm2). Such reproductive strategy emerges as an interesting approach, not only to enhance the out-of-season reproductive outcomes, but also to boost one of the main rulers defining the global reproductive efficiency of a heard, namely, the embryo implantation efficiency.

Sperm subpopulations influence the pregnancy rates in cattle.

This study aimed to study the characteristics and subpopulations of spermatozoa from bulls with low and high reproductive performance based on pregnancy rates. Based on historical records of pregnancy rate from four farms, 24 bulls were selected. Two groups were established, with low pregnancy rates (n = 12; LOW), including bulls that presented pregnancy rates <52.27% (33.33% to 51.81%); and a group with high pregnancy rates (n = 12; HIGH), with pregnancy rates >52.27% (52.27% to 69.64%), after fixed-time artificial insemination (FTAI). The thawed sperm straws were analysed to sperm kinetics, morphology, plasma membrane integrity and sperm subpopulations. The LOW group exhibited a higher proportion of static cells (p < .05). In contrast, the HIGH group showed greater percentages for membrane integrity and total and progressive motility, and cells with fast and medium velocity (p < .05). In the cluster procedures, four sperm subpopulations were established. The low-fertility bulls presented the highest percentage of subpopulation 2 (41.46%), characterized by slow and progressive spermatozoa. The high-fertility bulls exhibited the highest percentage of subpopulation 3 (37.17%), characterized by fast and nonlinear spermatozoa. Results from this study indicated that bulls with greater percentages of fast and nonlinear spermatozoa seem to have greater fertilization capacity and the subpopulations analysis can be considered a tool to identify ejaculates with high fertility.

Uso da IATF em pequenos rebanhos leiteiros como experiência de extensão rural no estado do Maranhão / Use of FTAI in small milk herbs as an experience jf rural extension in the state of Maranhão

In 2019, Brazil reached the third place in the world milk production ratio, preceded by the United States of America and India. However, most of the milk consumed by Brazilians is still imported, with export potential increasing as milk production is optimized. In Maranhão, dairy farming has grown over the past 20 years, being mainly composed of small dairy farmers. In order for there to be an improvement in production, an increase in the breeder's income and the productivity of the place, zootechnical, sanitary and reproductive control of the animals on the properties must be carried out. The inclusion of reproductive biotechnologies, such as Fixed Time Artificial Insemination (FTAI), is an important step that raises the technical level of the producer based on genetic improvement, however, the animals must have good nutritional, health and behavioral conditions to be able to use them. Therefore, in this work, the FTAI technique was included in the dairy cows of small breeders in the municipality of Lagoa Grande do Maranhão, in which they fit the required standards. The FTAI hormonal protocol was adopted in 44 dairy cows from 6 farms located in the municipality of Maranhão, in order to favor local milk productivity.

Mitos e realidades sobre a inseminação artificial em tempo fixo (IATF) em bovinos de corte / Myths and realities of timed artificial insemination in beef cattle

O sistema de cria é um dos principais setores da bovinocultura de corte, com impactos diretos na ocupação da terra (70% das pastagens são ocupadas pela cria) e na produtividade da cadeia da carne. O número e o peso dos bezerros produzidos por matriz e a idade das novilhas ao primeiro parto influenciam diretamente a eficiência do setor. As biotecnologias da reprodução, com destaque para a inseminação artificial em tempo fixo (IATF), têm colaborado significativamente para o desenvolvimento de um sistema de produção cada vez mais eficiente e sustentável. Em 2020 foram comercializadas no Brasil 23,7 milhões de doses de sêmen e 21,3 milhões de protocolos de IATF (90% das inseminações foram realizadas por IATF). Em 2002 eram utilizados apenas 100 mil procedimentos de IATF, que representavam somente 1% das inseminações realizadas. Nesse mesmo período (2002 a 2020), o percentual de matrizes inseminadas passou de 5% para 20% (acréscimo de 400%), com aumento de 213 vezes no empego da IATF. Os programas de IATF oferecem uma abordagem organizada e prática para o uso da IA, além de melhorarem a eficiência reprodutiva, genética e produtiva dos rebanhos. O uso da IATF antecipa a prenhez na estação de monta e a idade a primeira concepção das novilhas, aumentando significativamente a eficiência reprodutiva, produtiva e o retorno econômico do setor. Recentes estudos evidenciaram que os sistemas de cria que utilizam a IATF apresentam redução de 37,7% na emissão de CO2 equivalentes (produz mais bezerros de qualidade genética com menos matrizes que a monta natural), colaborando com a sustentabilidade da pecuária. Evidencia-se, também, que a nutrição, além de outros fatores, exerce papel importante na reprodução e afeta diretamente o desempenho da IATF. Entretanto, ainda existem mitos e realidades sobre os fatores que podem afetar o sucesso desta biotecnologia. O objetivo dessa revisão é apresentar e discutir os principais temas que impactam a eficiência da IATF em rebanhos de corte.

The cow-calf operation system is one is one of the main sectors of beef production, with direct impacts on land occupation (70% of pastures are occupied by the cow-calf operation system) and on the productivity of the meat chain. The number and the weight of calves produced per cow and the age of the heifer at first calving directly impact the efficiency of the sector. Reproductive biotechnologies, with emphasis on fixed-time artificial insemination (FTAI), have significantly contributed to the development of an efficient and sustainable production system. In 2020, 23.7 million doses of semen and 21.3 million FTAI protocols were marketed in Brazil (90% of inseminations were performed by FTAI). In 2002, only 100,000 FTAI procedures were used (a 213-fold increase in 19 years), which represented only 1% of the inseminations performed. During this same period (2002 to 2020), Brazil went from 5% to 20% of inseminated cow and heifers (increase of 400%). FTAI programs provide an organized and practical approach to the use of AI, as well as improve the reproductive, genetic and productive efficiency of the herds. The use of the FTAI anticipates the conception of cows in the breeding season and the age of the first conception of heifers, significantly increasing the reproductive and productive efficiency and the economic return of livestock. Recent studies have shown that breeding systems that use FTAI present a reduction of 37.7% in the emission of CO2 equivalents (it produces more calves of genetic quality with fewer dams than natural service), collaborating and with the sustainability of livestock. It is also evident that nutrition plays an important role in reproduction and directly affects the FTAI performance. However, there are still myths and realities about the factors that can affect the success of this biotechnology. The aim of this review is to present and discuss the main topics that impact the efficiency of FTAI in beef herds.

Effect of additional PGF2α dose on pregnancy rate in Nellore females subjected to FTAI / Efeito de dose adicional de PGF2α sobre a taxa de gestação de fêmeas bovinas Nelore submetidas a IATF

This study examined the effect of administering an additional dose of prostaglandin F2 alpha (PGF2α), in a fixed-time artificial insemination protocol (FTAI), on the fertility of female Nellore cattle. Two experiments were carried out: the first (Experiment I) took place in the state of Tocantins and the second (Experiment II) in the state of Pará, Brazil. In Experiment I (E1), 80 cows were used in three treatments (T1, T2 and T3) in which all received the same FTAI protocol. In T1 (n = 29), the cows received 12.5 mg of Dinoprost on day 9; in T2 (n = 28), they received the additional dose on day 10; and in T3 (n = 23; control group), the animals did not receive the additional PGF2α dose. Experiment II consisted of 147 bovine females distributed into two treatment groups, namely, T1 - 72 animals receiving the same protocol as T1 of E1; and T2 - 75 animals receiving the same protocol as T3 of E1. Statistical analysis was performed using SAS software, applying the PROC NPARWAY procedure for E1, and means were compared by the Wilcoxon test at the 5% significance level. In Experiment II, the data were subjected to analysis of variance by PROC GLIMMIX and means were compared by the T test at the 5% significance level. The following pregnancy rates were obtained in Experiment I: T1 - 62.06% (18/29); T2 - 57.14% (16/28); and T3 - 52.17% (12/23), with no significant difference observed between treatments. In Experiment II, pregnancy rate in T1 was 66.67% (48/72), whereas in T2 it was 41.33% (31/75), with a significant difference detected (P < 0.05). An additional dose of PGF2α provides an increase in pregnancy rate in Nellore females.(AU)

Objetivou-se avaliar o efeito da administração de uma dose adicional de prostaglandina F2 alfa (PGF2α) em protocolo de inseminação artificial em tempo fixo (IATF) sobre a fertilidade de fêmeas bovinas da raça Nelore. Foram realizados dois experimentos, sendo um (E1) no estado do Tocantins e o segundo (E2) no estado do Pará. No experimento 1 (E1) foram utilizadas 80 fêmeas bovinas distribuídas em três tratamentos (T1, T2 e T3), todos animais receberam o mesmo protocolo de IATF, diferindo no T1 (n=29), que recebeu 12,5 mg de Dinoprost no dia 9, T2 (n=28) recebeu a dose adicional no dia 10 e o T3 (n=23) - Grupo controle, que não recebeu a dose adicional de PGF2α. O experimento 2 (E2) constituído por 147 fêmeas bovinas distribuídas em dois tratamentos. T1: com 72 animais, recebendo mesmo protocolo do T1 do E1. T2: constituído por 75 animais, com protocolo idêntico ao T3 do E1. A análise estatistica foi realizada no programa SAS, sendo no E1 utilizando-se o PROC NPARWAY e as médias comparadas pelo teste de Wilcoxon com nível de significância de 5%. No E2 os dados foram submetidos à análise de variância pelo PROC GLIMMIX e as médias comparadas pelo teste T com nível de significância de 5%. No experimento 1 a taxa de prenhez no T1 foi de 62,06% (18/29), T2 de 57,14% (16/28) e T3 de 52,17% (12/23), não sendo observada diferença significativa entre os tratamentos. No experimento 2 a taxa de prenhez do T1 foi de 66,67% (48/72), enquanto T2 foi de 41,33% (31/75), verificando-se diferença significativa (P < 0,05). A dose adicional de PGF2α promoveu incremento na taxa de prenhez de fêmeas Nelore.(AU)

Sodium caseinate improves longevity and fertility of frozen bull semen.

This study aimed to evaluate the effect of sodium caseinate added into freezing extender on the sperm parameters of cryopreserved bull semen and in vitro and in vivo fertility. One ejaculate of 30 bulls was used and processed using Botu-Bov (Botupharma, Botucatu, Brazil) with the addition of 20% egg yolk (EY) or 15% egg yolk with 2% sodium caseinate (EY + SC), subsequently submitted to freezing. Semen from both groups were evaluated immediately after thawing (T0) and after thermic stress at 37 °C for 90 min (T90), for sperm kinetics, by CASA method, and plasma membrane integrity (PMI), superoxide (O2-) concentration and high mitochondrial potential (HMP) by flow cytometry. In vitro fertilization (IVF) was performed to assess embryo cleavage rate on day 3, and blastocyst rate on day 8. The in vivo fertility test was performed using fixed-time artificial insemination (FTAI). In sperm evaluation, trajectory velocity, linear velocity, curvilinear velocity, and lateral head movement were higher (P < 0.05) in EY + SC at T0. At T90, while rectilinearity and linearity did not differ between EY and EY + SC (P > 0.05), the other parameters evaluated were higher in EY + SC. Similarly, the integrity of the plasma and acrosomal membranes (iPAM) was higher (P < 0.05) at T90 in EY + SC, but did not differ (P > 0.05) between the groups at T0. For O2- and HMP, the values were lower (P < 0.05) in EY + SC group in both moments; furthermore, EY + SC showed higher cleavage and blastocyst rates in IVF. Likewise, pregnancy rates by FTAI were higher (P < 0.05) in the EY + SC group. In conclusion, the addition of sodium caseinate into freezing extender improves sperm parameters of frozen-thawed bull semen and fertility rates on during in vitro and in vivo tests.

Effect of additional PGF2α dose on pregnancy rate in Nellore females subjected to FTAI / Efeito de dose adicional de PGF2α sobre a taxa de gestação de fêmeas bovinas Nelore submetidas a IATF

This study examined the effect of administering an additional dose of prostaglandin F2 alpha (PGF2α), in a fixed-time artificial insemination protocol (FTAI), on the fertility of female Nellore cattle. Two experiments were carried out: the first (Experiment I) took place in the state of Tocantins and the second (Experiment II) in the state of Pará, Brazil. In Experiment I (E1), 80 cows were used in three treatments (T1, T2 and T3) in which all received the same FTAI protocol. In T1 (n = 29), the cows received 12.5 mg of Dinoprost on day 9; in T2 (n = 28), they received the additional dose on day 10; and in T3 (n = 23; control group), the animals did not receive the additional PGF2α dose. Experiment II consisted of 147 bovine females distributed into two treatment groups, namely, T1 - 72 animals receiving the same protocol as T1 of E1; and T2 - 75 animals receiving the same protocol as T3 of E1. Statistical analysis was performed using SAS software, applying the PROC NPARWAY procedure for E1, and means were compared by the Wilcoxon test at the 5% significance level. In Experiment II, the data were subjected to analysis of variance by PROC GLIMMIX and means were compared by the T test at the 5% significance level. The following pregnancy rates were obtained in Experiment I: T1 - 62.06% (18/29); T2 - 57.14% (16/28); and T3 - 52.17% (12/23), with no significant difference observed between treatments. In Experiment II, pregnancy rate in T1 was 66.67% (48/72), whereas in T2 it was 41.33% (31/75), with a significant difference detected (P < 0.05). An additional dose of PGF2α provides an increase in pregnancy rate in Nellore females.

Objetivou-se avaliar o efeito da administração de uma dose adicional de prostaglandina F2 alfa (PGF2α) em protocolo de inseminação artificial em tempo fixo (IATF) sobre a fertilidade de fêmeas bovinas da raça Nelore. Foram realizados dois experimentos, sendo um (E1) no estado do Tocantins e o segundo (E2) no estado do Pará. No experimento 1 (E1) foram utilizadas 80 fêmeas bovinas distribuídas em três tratamentos (T1, T2 e T3), todos animais receberam o mesmo protocolo de IATF, diferindo no T1 (n=29), que recebeu 12,5 mg de Dinoprost no dia 9, T2 (n=28) recebeu a dose adicional no dia 10 e o T3 (n=23) - Grupo controle, que não recebeu a dose adicional de PGF2α. O experimento 2 (E2) constituído por 147 fêmeas bovinas distribuídas em dois tratamentos. T1: com 72 animais, recebendo mesmo protocolo do T1 do E1. T2: constituído por 75 animais, com protocolo idêntico ao T3 do E1. A análise estatistica foi realizada no programa SAS, sendo no E1 utilizando-se o PROC NPARWAY e as médias comparadas pelo teste de Wilcoxon com nível de significância de 5%. No E2 os dados foram submetidos à análise de variância pelo PROC GLIMMIX e as médias comparadas pelo teste T com nível de significância de 5%. No experimento 1 a taxa de prenhez no T1 foi de 62,06% (18/29), T2 de 57,14% (16/28) e T3 de 52,17% (12/23), não sendo observada diferença significativa entre os tratamentos. No experimento 2 a taxa de prenhez do T1 foi de 66,67% (48/72), enquanto T2 foi de 41,33% (31/75), verificando-se diferença significativa (P < 0,05). A dose adicional de PGF2α promoveu incremento na taxa de prenhez de fêmeas Nelore.

Can cover sheath model influence semen retention in AI-gun trials and pregnancy rates of cows inseminated at a fixed-time? / A bainha utilizada na inseminação artificial (IA) pode influenciar a retenção residual de sêmen e as taxas de concepção de vacas inseminadas em tempo fixo?

The achievement of satisfactory results in fixed-time artificial insemination (FTAI) protocols depends on several factors, such as the quality of the materials used to perform the artificial insemination (AI). In this context, three experiments were conducted to evaluate the effect of the cover sheath model on the residual retention of semen during AI and the pregnancy rates of cows submitted to FTAI. In Experiment 1, 400 straws of cryopreserved bovine semen were thawed and repacked in samples with similar weight and volume characteristics. Each new dose of semen (n = 300) was mounted using one of three AI cover sheath models (n = 100 semen/sheath doses): the main brand in the global market (G1), the main model in the Brazilian market (G2), and a model marketed as having a low residual semen retention rate (G3), to determine the percentages of seminal elimination (PSEs) during AI. In Experiment 2, 464 Nelore cows were synchronized through intravaginal progesterone implants and inseminated using the same cover sheaths as those tested in Experiment 1, which were grouped into classes (conventional: G1 and G2 [n = 225]; and low reflux: G3 [n = 239]). In Experiment 3, 859 Nelore cows were synchronized and inseminated as described above, using the same cover sheaths previously tested. After each AI, cover sheaths were visually inspected for the presence of residual semen and pregnancy diagnosis was performed 35 days after FTAI (Experiments 2 and 3). The PSEs in Experiment 1 were 91.7%, 90.6% and 96.5% for groups G1, G2 and G3, respectively (P = 0.05). The pregnancy rates in Experiment 2 were 53.33% and 58.16% for the conventional and low reflux model, respectively (P > 0.05), but there were differences (P = 0.05) among the cover sheath models employed for AI (G1 - 57.72% [71/123]; G2 - 48.04% [49/102]; G3 - 58.16% [139/239]). Additionally, a lower semen reflux incidence (P < 0.05) was observed in the low residual sperm retention model (0.72%) in Experiment 3, compared to the main international (10.42%) and national (22.99%) market models. In conclusion, residual semen retention occurs regardless of the cover sheath model used for AI. However, the PSE is influenced by the model and quality of cover sheath used. According to the results, the cover sheath represents a factor that may compromise the pregnancy rates of synchronized cows for FTAI.(AU)

Diversos fatores podem influenciar os resultados de concepção dos programas de inseminação artificial em tempo-fixo (IATF), como por exemplo a qualidade dos materiais utilizados para a inseminação artificial (IA). Nesse contexto, três experimentos foram conduzidos para testar o efeito da bainha sobre o percentual de retenção residual de sêmen nos aplicadores de IA e nas taxas de concepção de vacas submetidas à IATF. No Experimento 1 foram descongeladas 400 palhetas de sêmen bovino criopreservado, que foram re-envasadas para compor amostras com características de peso e volume semelhantes. Cada nova dose de sêmen (n=300) foi montada em um dos três modelos de bainhas de inseminação artificial em teste (n=100 doses de sêmen/ bainha): marca líder no mercado global (G1), modelo líder no mercado brasileiro (G2), modelo comercializado como de baixa taxa de retenção residual de sêmen (G3), para determinação do percentual de eliminação seminal (PES). No Experimento-2 foram selecionadas 464 vacas Nelore, sincronizadas através de implantes intravaginais de progesterona e inseminadas empregando as mesmas bainhas do experimento anterior, porém agrupadas em classes (convencional: G1 e G2 [n = 225]; ou baixo refluxo: G3 [n = 239]). No Experimento-3 859 vacas Nelore foram sincronizadas e inseminadas com sêmen previamente selecionado, utilizando os mesmos modelos de bainhas testadas nos experimentos anteriores. Após cada IATF as bainhas foram inspecionadas visualmente para detecção de presença residual de sêmen e o diagnóstico de gestação foi realizado a partir de 35 dias após a IATF (Experimentos 2 e 3). O PES foi de 91,7%, 90,6% e 96,5%, respectivamente para os grupos G1, G2 e G3 (P = 0,05). As taxas de concepção no Experimento-2 foram de 53,33% e 58,16%, respectivamente para o modelo convencional e de baixo refluxo (P > 0,05), porém havendo diferenças (P = 0,05) de acordo com o modelo da bainha empregada para a IA (57,72% [71/123], 48,04% [49/102] e 58,16% [139/239], respectivamente para os grupos G1, G2 e G3). Menor incidência de refluxo de sêmen (P < 0,05) foi observado para o modelo de baixa retenção residual de espermatozoides (0,72%), frente aos modelos líderes do mercado internacional (10,42%) e nacional (22,99%; Experimento-3). Conclui-se que ocorre retenção residual de sêmen, independente do modelo de bainha utilizada para a IA. No entanto, a PES é influenciada pelo modelo e qualidade da bainha utilizada para inseminação artificial, fator que pode comprometer os índices de concepção de vacas sincronizadas para IATF.(AU)

Comparison between in vitro embryo production using Y-sorted sperm and timed artificial insemination with non-sorted sperm to produce crossbred calves.

Due to the increasing use of in vitro embryo production (IVEP) and the importance of crossbreeding for beef production, pregnancy rates of Nelore recipients were evaluated following Fixed Time Embryo Transfer with fresh or vitrified IVEP embryos produced with Y-sorted sperm of Angus bulls (B. taurus) or Fixed Time Artificial Insemination using non-sorted sperm. For IVEP in Experiment 1, oocytes were obtained using Ovum Pick Up (OPU) (n = 84 embryos) or from ovaries from a slaughterhouse (SLAUGHTER, n = 66 embryos). In Experiment 2, with oocytes obtained by OPU, IVEP embryos were fresh (FRESH, n = 271) or after vitrification/warming (VITRIFIED, n = 79) and PR was compared with FTAI (n = 239). In Experiment 1, cleavage rates were 63.8% and 39.1% for OPU and SLAUGHTER groups, respectively (P = 0.02), and blastocyst rates were 30.5% and 14.7%, respectively (P = 0.09). The PR was similar when considering the source of oocytes (OPU = 35.7%; SLAUGHTER = 25.8%; P = 0.17). In Experiment 2, there was no difference in PR for FRESH or VITRIFIED embryos (34.3% and 30.4%, respectively, P = 0.72), but lesser than FTAI (47.7, P = 0.002). It is concluded that the IVEP with Y-sorted sperm associated with vitrification or embryos produced with oocytes from different sources did not affect PR when there was transfer of crossbred embryos into recipients, and can optimize large-scale application of IVEP technology; however, FTAI pregnancy rates with non-sex sorted sperm were greater.