Prohibition of hormones in animal reproduction: what to expect and what to do?

As our understanding of ovarian function in cattle has improved, our ability to control it has also increased. The development of Fixed-Time Artificial Insemination (FTAI) protocols at the end of the 20th century has increased exponentially the number of animals inseminated over the last 20 years. The main reasons for this growth were the possibility of obtaining acceptable pregnancy rates without heat detection and, above all, the induction of cyclicity in suckled cows in postpartum anestrus and prepubertal heifers at the beginning of the breeding season. Most FTAI treatments in South America have been based on the use of progesterone (P4) releasing devices and estradiol to synchronize both follicular wave emergence and ovulation, with pregnancy rates ranging from 40 to 60%. These protocols are implemented on a regular basis, allowing producers access to high-quality genetics, and increasing the overall pregnancy rates during the breeding season. In addition, it provided the professionals involved in these programs with a new source of income and the diversification of their practices into activities other than their usual clinical work. Many of these practices are now apparently at risk from restrictions on the use of estradiol by the European Union (EU) and other countries. However, the development of alternative protocols based on GnRH, with P4 devices and eCG and other new products that are not in the market yet will allow us to adapt to the new times that are coming. Logically, the challenge has already been raised and we must learn to use alternative protocols to try to continue increasing the use of this technology in beef and dairy herds. The objective of the present review is to describe the main aspects of banning estradiol in livestock production, the negative impacts on reproductive efficiency, and to present some alternative FTAI protocols for dairy and beef cattle.(AU)

Fatores que impactam na eficiência reprodutiva de vacas de corte / Factors that impact the reproductive efficiency of beef cows

A maior produtividade na pecuária está correlacionada com a eficiência reprodutiva do rebanho. As biotécnicas da reprodução, principalmente os protocolos de sincronização da ovulação, são de grande importância para otimizar a produção e acelerar o ganho genético em rebanhos de corte e de leite. No entanto, alguns fatores como a categoria animal, o manejo reprodutivo implementado na propriedade e o reprodutor utilizado podem afetar os resultados de fertilidade nos protocolos de IATF. Dessa maneira, algumas estratégias foram desenvolvidas para contornar alguns desafios inerentes a vacas de corte em anestro pós-parto e aumentar a eficiência reprodutiva dessas fêmeas. Dentre as estratégias, destacam-se a utilização de progesterona e a suplementação energética/proteica previamente ao início do protocolo de IATF.(AU)

The reproductive efficiency of the herd is correlated with higher productivity in livestock. Reproduction biotechniques as ovulation synchronization protocols are important to optimize production and accelerate genetic profit in beef and dairy herds. However, some factors such as the animal category, the reproductive management implemented on the farm and the sire used can affect the fertility results in the TAI protocols. In this way, some strategies were developed to overcome some challenges of postpartum anestrus beef cows and to increase the reproductive efficiency of these cows. The use of progesterone and energy/protein supplementation before starting the TAI protocol stand out are the strategies.(AU)

Impacts of trace element supplementation on productive/reproductive postpartum performances of grazing dairy heifers from volcanic soils

This study has been designed to evaluate the effect of trace elements (TE) on the reproductive and productive performances of postpartum Holstein Friesian heifers, fed on pasture with origin on volcanic soils, poor in TE. Twenty-six heifers pregnant were divided into two groups: experimental (EG) and control (CG) groups (n=13, each group). For animals belonging to the EG, two intra-ruminal capsules with TE were administrated 60 days before partum, while in the CG, no boluses were administered. All animals' blood was collected weekly to assess progesterone levels by the ELFA technique for 11 weeks after partum. TE were evaluated on blood by AAS when the experience started, on the day of delivery, and after 60 days. Before calving, no statistical differences were observed between groups for the trace elements, although it has been noticed that heifers had deficiencies in Selenium, Copper, and Iodine. On the calving day and 60 days after, a statistical increase (p<0.05) in serum Copper and Selenium was observed in the animals belonging to the EG. For the other TE, no statistical differences were observed. Concerning reproductive characteristics, the EG, at five weeks postpartum, 70% of the cows were cyclic, while in the CG in the same period, 33% of animals showed signs of ovarian activity. At the level of productive parameters, no differences were observed between groups. The results obtained by the present study allow concluding that, under our experimental conditions, the administration of trace elements, in addition to reducing postpartum anestrus, increases the quality of the corpus luteum in the postpartum period of heifers.

Plasma metabolite changes in anestrous dairy cows with negative energy balance identified using 1H NMR technology / [Alterações do metabólito plasmático em vacas leiteiras com balanço energético negativo identificado usando a tecnologia 1H NMR]

The objective of the present study was to investigate the different plasma metabolites between anestrus and estrus postpartum dairy cows and to provide a theoretical basis for prevention of anestrus in dairy farm cows. In the experiment, one hundred and sixty-seven Holstein dairy cows were selected with similar age and parity. According to the concentration of ß-hydroxybutyric acid, non-esterified fatty acids and glucose in plasma during 14 to 21 days in milk, all dairy cows were determined as having a status of energy balance. According to the results of clinical symptom, rectal and B ultrasound examination at 60 to 90 days postpartum, these cows were divided into twenty estrus and twenty-four anestrus group, other dairy cows were removed. 1H nuclear magnetic resonance technology was utilized to detect the plasma metabolites changes and screen different plasma metabolites between anestrus and estrus cows. Ten different metabolites including alanine, glutamic acid, asparagine, creatine, choline, phosphocholine, glycerophosphocholine, low-density lipoprotein, and very-low-density lipoprotein were significantly decreased in anestrous cows compared with estrous cows. Metabolic pathway analyses indicated that differential metabolites were primarily involved in amino acid and glycerophospholipid metabolism. These metabolites and their enrichment pathways indicate that reduced steroid hormone synthesis precursors result in lower levels of estradiol and progesterone and cause anestrus in negative energy balance. These data provide a better understanding of the changes that may affect estrus of postpartum dairy cows at NEB status and lay the ground for further research.(AU)

O objetivo do presente estudo foi investigar os diferentes metabolitos do plasma entre o cio e o cio pós-parto de vacas leiteiras e fornecer uma base teórica para a prevenção do cio de vacas em fazendas de leite. No experimento, foram selecionadas 127 vacas leiteiras Holstein com idade e paridade similares. De acordo com a concentração de ß- ácido hidroxibutírico, ácidos graxos não esterificados e glicose no plasma entre 14 e 21 dias no leite, todas as vacas leiteiras foram determinadas em estado de equilíbrio energético. De acordo com os resultados dos sintomas clínicos, do exame de ultra-som retal e B aos 60 a 90 dias pós-parto, estas vacas foram divididas em vinte cios e vinte e quatro grupos de cio, outras vacas leiteiras foram removidas. A tecnologia de ressonância magnética nuclear 1H foi utilizada para detectar as alterações dos metabólitos plasmáticos e para triar diferentes metabólitos plasmáticos entre as vacas do cio e do cio. Dez diferentes metabólitos incluindo alanina, ácido glutâmico, asparagina, creatina, colina, fosfocholina, glicerofosfocolina, lipoproteína de baixa densidade e lipoproteína de muito baixa densidade foram significativamente diminuídos nas vacas antróficas em comparação com as vacas estro. As análises da via metabólica indicaram que os metabólitos diferenciais estavam principalmente envolvidos no metabolismo de aminoácidos e glicerofosfolipídios. Estes metabólitos e suas vias de enriquecimento indicam que a redução dos precursores da síntese de hormônios esteróides resulta em níveis mais baixos de estradiol e progesterona e causa anestros no balanço energético negativo. Estes dados fornecem uma melhor compreensão das mudanças que podem afetar o cio das vacas leiteiras pós-parto no estado de NEB e preparam o terreno para mais pesquisas.(AU)

Reproductive disorders in does experimentally infected by Toxoplasma gondii / Distúrbios reprodutivos em cabras experimentalmente infectadas por Toxoplasma gondii

The aim of this study was to describe the reproductive disorders related to experimental infection by artificial insemination with semen contaminated with Toxoplasma gondii of four goats in the chronic phase of the infection. In the end of the study, the does were submitted to necropsy, and PCR and histopathological evaluations were performed. Among infected does that exhibited embryonic loss, two were in anestrus and two exhibited repeated estrus. One of the latter animals exhibited clinical signs of estrus at seven-day intervals, whereas the other had a 21-day estrous cycle. However, both does were naturally mated on subsequent natural estrous and were not able to get pregnant until the end of the experiment (90 d). Two of the goats exhibited abnormalities in the ultrasound examinations, one of which was an ovarian cyst, while the other was a hydrosalpinx, both of which were confirmed in the post-mortem examination. The main microscopic injuries in this group were neutrophilic infiltration of the lungs, interstitial glomerulonephritis and neutrophilic infiltration of the liver. T. gondii DNA was found in the organs (heart and brain) of three does. In conclusion, does infected with Toxoplasma gondii in semen at the time of artificial insemination display reproductive disorders in the chronic phase of infection that might be associated with toxoplasmosis.

Objetivou-se descrever os distúrbios reprodutivos associados à infecção experimental por Toxoplasma gondii através da inseminação artificial com sêmen contaminado em quatro cabras no estágio crônico da infecção. As características do trato reprodutor foram avaliadas através de ultrassonografia transretal, visando o diagnóstico gestacional ou de desordens reprodutivas, após a infecção experimental. Ao final do experimento, os animais foram necropsiados e avaliações histopatológicas e PCR foram realizados. Dentre os animais infectados que exibiram mortalidade embrionária, duas apresentaram anestro e duas apresentaram repetição de estro, sendo que destas uma apresentou intervalos entre estros reduzido (sete dias) e outra em intervalo regular (21 dias). Todavia, ambas foram submetidas a monta natural durante os estros naturais subsequentese não foi confirmada gestação até o final do experimento (90 dias). Duas cabras exibiram alterações nos exames de ultrassonografia, sendo identificadas um cisto ovariano, e uma hidrossalpinge, ambas confirmadas no exame post-mortem. As principais lesões microscópicas nesse grupo foram infiltração neutrofílica dos pulmões, glomerulonefrite intersticial e infiltração neutrofílica do fígado. O DNA de T. gondii foi encontrado nos órgãos (coração e cérebro) de três cabras. Em conclusão, cabras infectadas comsêmen contendoT. gondii no momento da inseminação artificial apresentam distúrbios reprodutivos na fase crônica da infecção que podem estar associados à toxoplasmose.

Prevalência de cistos ovarianos em vacas de alta produção submetidas a sistema de confinamento e dieta total / Prevalence of ovarian cysts in production high cows under containment system and diet total

Objetivou-se avaliar prevalência de cistos ovarianos em vacas leiteiras de alta produção, no pós-parto, submetidas ao regime de dieta total em três sistemas diferentes: Compost Barn, Free Stall e confinamento a céu aberto no sudoeste do estado de Goiás. Foram avaliadas 1600 vacas, HPB, de sete rebanhos, das quais 792 (49,5%) estavam vazias e com atraso nos protocolos reprodutivos. Ao exame ultrassonográfico o escore ovariano foi classificado em: Grau 1 (61,4%), Grau 2 (18,1%), Grau 3 (4,0%) e Cistos Ovarianos (16,5%). Quanto ao sistema de produção as prevalências de cistos foram: 16% no Free Stall, 17,2% no Compost Barn e 16,2% no confinamento a céu aberto, diferenças somente numéricas, mas não significativas estatisticamente. 84,7% (n=131) dos animais estavam em anestro, na presença do diagnóstico cisto folicular. 67,7% desses animais, situavam-se entre 60 a 180 dias pós-parto. Divididos em 27,5% entre 60 e 90 dias, 24,5% entre 91 e 120 dias, 15,5% entre 121 e 150 dias e 32,5% entre 151 e 500. A prevalência dos cistos em função do número de lactações foi: 29,8% na primeira, 26,7% na segunda, 24,4% na terceira, 5,3% na quarta, 4,6% na quinta e 9,2% na sexta, resultados estatísticos significativos para maior ocorrência de cistos nas três primeiras lactações. Quanto ao escore de condição corporal 62,6% das vacas com cisto ovariano mostraram-se com escore entre 2,0 a 2,5, 25,2% entre 2,6 a 3,0 e 12,2% entre 3,1 a 4,0, resultados significativos, e a chance de vacas em balanço energético negativo desenvolverem cistos foi 5,1 vezes maior, quando comparadas com animais em escore corporal ideal. Os cistos foliculares apresentam-se com elevada casuística em vacas de alta produção leite, impactando em subfertilidade e prejuízos importantes na pecuária leiteira mundial, assim, faz-se necessário outros estudos visando o desenvolvimento de medidas preventivas mais eficazes no controle deste quadro.(AU)

This study aimed to evaluate the follicular cysts prevalence in high production dairy cows, post-partum, under total diet regime in three different systems: Compost Barn, Free Stall and opened feedlot. There were evaluated 1600 cows, HPB, seven flocks, of which 792 (49.5%) were empty and late in the reproductive protocols. The examination sonographic ovarian score was distributed as: Score 1 (61.4%), Score 2 (18,1) Score 3 (4.0%) and Cystic Ovary (16.5%). As for the production system the cysts prevalence were 16% in Free Stall, 17.2% in Compost Barn and 16.2% in opened feedlot, without significant difference. 84.7% (n = 131) of animals were in anestrus in the presence of diagnosis follicular cyst. 60.7% of animal with follicular cysts were 60 to 180 days postpartum. Divided in 27.5% between 60 and 90 days, 24.5% between 91 and 120 days, 15.5% between 121 and 150 days and 32.5% between 151 and 500 postpartum. The cysts prevalence according to lactation number were: 29.8% in first, 26.7% in second, 24.4% in third, 5.3% in fourth, 4.6% in fifth and 9.2% in sixth, statistically significant results to higher cysts occurrence in the first three lactations. For body condition score 62.6% of animals with ovarian cyst were with scores from 2.0 to 2.5, 25.2% with a score of 2.6 to 3.0 and 12.2% with score of 3.1 to 4.0 also significant results. Where the chance of cows with low body score develop cysts was 5.1 times higher compared to animals with good score. Follicular cysts present high prevalence in high producing dairy cows, impacting sub-fertility and causing important damage in global dairy farming, thus, it is necessary further studies for the development of more effective preventive measures to control this situation.(AU)

Prevalência de cistos ovarianos em vacas de alta produção submetidas a sistema de confinamento e dieta total / Prevalence of ovarian cysts in production high cows under containment system and diet total

Objetivou-se avaliar prevalência de cistos ovarianos em vacas leiteiras de alta produção, no pós-parto, submetidas ao regime de dieta total em três sistemas diferentes: Compost Barn, Free Stall e confinamento a céu aberto no sudoeste do estado de Goiás. Foram avaliadas 1600 vacas, HPB, de sete rebanhos, das quais 792 (49,5%) estavam vazias e com atraso nos protocolos reprodutivos. Ao exame ultrassonográfico o escore ovariano foi classificado em: Grau 1 (61,4%), Grau 2 (18,1%), Grau 3 (4,0%) e Cistos Ovarianos (16,5%). Quanto ao sistema de produção as prevalências de cistos foram: 16% no Free Stall, 17,2% no Compost Barn e 16,2% no confinamento a céu aberto, diferenças somente numéricas, mas não significativas estatisticamente. 84,7% (n=131) dos animais estavam em anestro, na presença do diagnóstico cisto folicular. 67,7% desses animais, situavam-se entre 60 a 180 dias pós-parto. Divididos em 27,5% entre 60 e 90 dias, 24,5% entre 91 e 120 dias, 15,5% entre 121 e 150 dias e 32,5% entre 151 e 500. A prevalência dos cistos em função do número de lactações foi: 29,8% na primeira, 26,7% na segunda, 24,4% na terceira, 5,3% na quarta, 4,6% na quinta e 9,2% na sexta, resultados estatísticos significativos para maior ocorrência de cistos nas três primeiras lactações. Quanto ao escore de condição corporal 62,6% das vacas com cisto ovariano mostraram-se com escore entre 2,0 a 2,5, 25,2% entre 2,6 a 3,0 e 12,2% entre 3,1 a 4,0, resultados significativos, e a chance de vacas em balanço energético negativo desenvolverem cistos foi 5,1 vezes maior, quando comparadas com animais em escore corporal ideal. Os cistos foliculares apresentam-se com elevada casuística em vacas de alta produção leite, impactando em subfertilidade e prejuízos importantes na pecuária leiteira mundial, assim, faz-se necessário outros estudos visando o desenvolvimento de medidas preventivas mais eficazes no controle deste quadro.

This study aimed to evaluate the follicular cysts prevalence in high production dairy cows, post-partum, under total diet regime in three different systems: Compost Barn, Free Stall and opened feedlot. There were evaluated 1600 cows, HPB, seven flocks, of which 792 (49.5%) were empty and late in the reproductive protocols. The examination sonographic ovarian score was distributed as: Score 1 (61.4%), Score 2 (18,1) Score 3 (4.0%) and Cystic Ovary (16.5%). As for the production system the cysts prevalence were 16% in Free Stall, 17.2% in Compost Barn and 16.2% in opened feedlot, without significant difference. 84.7% (n = 131) of animals were in anestrus in the presence of diagnosis follicular cyst. 60.7% of animal with follicular cysts were 60 to 180 days postpartum. Divided in 27.5% between 60 and 90 days, 24.5% between 91 and 120 days, 15.5% between 121 and 150 days and 32.5% between 151 and 500 postpartum. The cysts prevalence according to lactation number were: 29.8% in first, 26.7% in second, 24.4% in third, 5.3% in fourth, 4.6% in fifth and 9.2% in sixth, statistically significant results to higher cysts occurrence in the first three lactations. For body condition score 62.6% of animals with ovarian cyst were with scores from 2.0 to 2.5, 25.2% with a score of 2.6 to 3.0 and 12.2% with score of 3.1 to 4.0 also significant results. Where the chance of cows with low body score develop cysts was 5.1 times higher compared to animals with good score. Follicular cysts present high prevalence in high producing dairy cows, impacting sub-fertility and causing important damage in global dairy farming, thus, it is necessary further studies for the development of more effective preventive measures to control this situation.

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

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

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

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

Occurrence of subclinical endometritis in dairy cattle and effect on reproductive efficiency

Background: Subclinical endometritis (SE) have a negative impact on fertility due to an absence of clinical signs which difficult its diagnosis and treatment. The prevalence and impact of the disease on the reproductive status of dairy herds is not known in the region, the objective of the present study was to determine the prevalence of the disease and its effect on the reproductive efficiency in cows of the dairy area from Putumayo State, Colombia.Materials, Methods & Results: Cross-sectional study was made of 166 dairy cows from 30 days postpartum in the municipalities: Santiago, Sibundoy, Colon, and San Francisco. Reproductive evaluation and endometrial cytology were made to establish the SE prevalence determining subsequently the number of open days. Cow whit more than 120 days in milk (DIM) and without confirmed pregnancy was defined as “not reproductive efficiency”. Association between SE and reproductive efficiency was established through Odds Ratio from contingency tables. Bias and confusion control was made through stratified analysis. Results showed 32 cows without changes in reproductive clinical evaluation and inflammatory changes in cytological evaluation (PMNn >5%) for a SE prevalence of 19.27%. Disease occurs most frequently in Colón (23.10%) but the frequency of the disease was not different among the regions (P > 0.05). The group of animals with the greatest days open (DO) mean (161 DIM) had a normal ovarian function and subclinical endometritis. The 6.6% of cows had a poor reproductive prognosis (subclinical endometritis, anestrous and 144 DIM). For the stratified analysis (controlling by anestrus) was estimated the crude OR (OR 5.93; P < 0.05; CI 95% 2.56-14.6) and adjusted ORMH (OR 5.78; P < 0.05; CI 95% 2.39-13.9).[...]

Occurrence of subclinical endometritis in dairy cattle and effect on reproductive efficiency

Background: Subclinical endometritis (SE) have a negative impact on fertility due to an absence of clinical signs which difficult its diagnosis and treatment. The prevalence and impact of the disease on the reproductive status of dairy herds is not known in the region, the objective of the present study was to determine the prevalence of the disease and its effect on the reproductive efficiency in cows of the dairy area from Putumayo State, Colombia.Materials, Methods & Results: Cross-sectional study was made of 166 dairy cows from 30 days postpartum in the municipalities: Santiago, Sibundoy, Colon, and San Francisco. Reproductive evaluation and endometrial cytology were made to establish the SE prevalence determining subsequently the number of open days. Cow whit more than 120 days in milk (DIM) and without confirmed pregnancy was defined as “not reproductive efficiency”. Association between SE and reproductive efficiency was established through Odds Ratio from contingency tables. Bias and confusion control was made through stratified analysis. Results showed 32 cows without changes in reproductive clinical evaluation and inflammatory changes in cytological evaluation (PMNn >5%) for a SE prevalence of 19.27%. Disease occurs most frequently in Colón (23.10%) but the frequency of the disease was not different among the regions (P > 0.05). The group of animals with the greatest days open (DO) mean (161 DIM) had a normal ovarian function and subclinical endometritis. The 6.6% of cows had a poor reproductive prognosis (subclinical endometritis, anestrous and 144 DIM). For the stratified analysis (controlling by anestrus) was estimated the crude OR (OR 5.93; P < 0.05; CI 95% 2.56-14.6) and adjusted ORMH (OR 5.78; P < 0.05; CI 95% 2.39-13.9).[...](AU)

Genetic market in cattle (Bull, AI, FTAI, MOET and IVP): financial payback based on reproductive efficiency in beef and dairy herds in Brazil

A number of reproductive biotechnologies are currently available to multiply offspring from high genetic merit animals to enhance reproductive efficiency and profitability both in dairy and beef herds. Some of these technologies such as fixed time artificial insemination (FTAI), when correctly implemented,generally allow greater reproductive performance than natural breeding. Besides the use of frozen-thawed semen during artificial insemination, cattle recipients can also be synchronized to receive embryos (produced in vivo or in vitro) at set dates with fertility results that usually outperforms natural breeding as well as artificial insemination (AI), particularly during warm seasons and in repeat breeders cows. Altogether, the use of hormonal programs to synchronize ovulation time simplify field routine, can easily fix physiological limitations related to postpartum anestrus (beef cows), poor estrus detection efficiency due to less evident estrus signs (dairy cows), making AI and ET viable to commercial herds both in terms of results and economical returns.

Genetic market in cattle (Bull, AI, FTAI, MOET and IVP): financial payback based on reproductive efficiency in beef and dairy herds in Brazil

A number of reproductive biotechnologies are currently available to multiply offspring from high genetic merit animals to enhance reproductive efficiency and profitability both in dairy and beef herds. Some of these technologies such as fixed time artificial insemination (FTAI), when correctly implemented,generally allow greater reproductive performance than natural breeding. Besides the use of frozen-thawed semen during artificial insemination, cattle recipients can also be synchronized to receive embryos (produced in vivo or in vitro) at set dates with fertility results that usually outperforms natural breeding as well as artificial insemination (AI), particularly during warm seasons and in repeat breeders cows. Altogether, the use of hormonal programs to synchronize ovulation time simplify field routine, can easily fix physiological limitations related to postpartum anestrus (beef cows), poor estrus detection efficiency due to less evident estrus signs (dairy cows), making AI and ET viable to commercial herds both in terms of results and economical returns.(AU)

Influence of Male to Female Ratio on Hormone Profiles and Reproductive Performance of Anestrus Postpartum Ewes Subjected to the Male Effect

Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios.Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams  (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus wer

Influence of male to female ratio on hormone profiles and reproductive performance of anestrus postpartum ewes subjected to the male effect

Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios. Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus [...](AU)

Influence of male to female ratio on hormone profiles and reproductive performance of anestrus postpartum ewes subjected to the male effect

Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios. Material, Methods & Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus [...]

Validation of an immunoassay system for progesterone dosage and physiological responses of postpartum cows treated with long-acting injectable progesterone

Estudos foram desenvolvidos com o objetivo de validar um kit para dosagem de P4 em bovinos e avaliar o perfil de progesterona (P4) circulante e dinâmica ovariana após tratamento com progesterona injetável de longa ação (P4i) em vacas pós-parto. No primeiro estudo, foram realizados testes para validação de um kit comercial baseado em tecnologia quimioluminescente, Immulite 1000 Progesterone (LKPW1), para dosagem de P4 em bovinos. Para tal, curvas padrão foram produzidas a partir de amostras de plasma de garrotes castrados enriquecidas com concentrações conhecidas de P4, e a precisão, exatidão, efeito de anticoagulante e efeito residual foram avaliados. O método se mostrou exato para amostras com concentração de P4 entre 0.3 e 10.0 ng/mL e preciso para amostras entre 0,5 e 20,0 ng/mL. Além disso, os resultados fornecidos pelo kit são fidedignos às concentrações nas amostras, sejam elas soro ou plasma, não sendo necessária a análise de curvas padrão a cada ensaio. No segundo estudo, primíparas Nelore (n = 28) em anestro pós-parto foram aleatoriamente designadas a receber 1 mL de veículo oleoso (Con; n = 14) ou 1 mL de veículo com 150 mg de P4i (P4i; n = 14) no D0. A partir de então, durante 21 d, foram realizadas colheitas de sangue e ultrassonografia ovariana em todos os animais, além de observação da expressão de cio entre D8 e D15. De modo geral, nenhuma vaca expressou cio, permanecendo anovulatórias até o D20. No D1, vacas do grupo P4i tiveram um pico de P4 circulante (3,0 ng/mL), permanecendo acima de 0,5 ng/mL por 7 d, enquanto no grupo Con a P4 circulante se manteve abaixo de 0,2 ng/mL durante todo o estudo. Vacas do grupo P4i apresentaram maior diâmetro do folículo dominante durante o estudo (12,8 ± 0,5 vs. 10,6 ± 0,6 mm), maior intervalo entre ondas (9,4 ± 1,0 vs. 6,5 ± 0,7 d) e mais dias com folículos com capacidade ovulatória nos ovários em comparação ao grupo Con (12,5 ± 0,5 vs. 8,3 ± 1,3 d). Sendo assim, apesar de ineficiente na indução de ciclicidade em vacas pós-parto, o tratamento com P4i promoveu alterações na dinâmica ovariana e perfil circulante de P4 que podem servir de base para novos estudos e estratégias de uso. Além disso, o kit testado apresentou alto potencial para uso na quantificação de P4 circulante em bovinos. Contudo, ainda são necessários outros testes e análises de maior número de amostras para confirmar sua robustez.

Studies were conducted to validate a kit for measuring P4 in cattle and to evaluate the circulating progesterone (P4) profile and ovarian dynamics after treatment with long-acting injectable progesterone (P4i) in postpartum cows. In the first study, tests were conducted to validate a commercial kit based on chemiluminescent technology, Immulite 1000 Progesterone (LKPW1), to measure P4 in cattle. For this purpose, standard curves were generated from plasma samples of steers enriched with known concentrations of P4, and the precision, accuracy, anticoagulant effect, and residual effect were evaluated. The method proved to be accurate for samples with a P4 concentration between 0.3 and 10.0 ng/mL and precise for samples between 0.5 and 20.0 ng/mL. In addition, the results provided by the equipment are reliable to the concentrations in the samples, whether using serum or plasma, and it is not necessary to analyze standard curves for each assay. In the second study, Nelore primiparous (n = 28) in postpartum anestrus were randomly assigned to receive 1 mL of oily vehicle (Con; n = 14) or 1 mL of oily vehicle with 150 mg of P4i (P4i; n = 14) on D0. Thereafter, for 21 d, blood samples and ovarian ultrasonography were performed in all animals, in addition to observation of expression of estrus between D8 and D15. In general, no cow expressed estrus, remaining anovulatory until D20. On D1, cows in the P4i group had a peak of circulating P4 (3.0 ng/mL), remaining above 0.5 ng/mL for 7 d, while in the Con group, circulating P4 remained below 0.2 ng/mL throughout the study. Cows in the P4i group had a larger diameter of the dominant follicle during the study (12.8 ± 0.5 vs. 10.6 ± 0.6 mm), a longer interval between waves (9.4 ± 1.0 vs. 6.5 ± 0.7 d) and more days with follicles with ovulatory capacity in the ovaries compared to the Con group (12.5 ± 0.5 vs. 8.3 ± 1.3 d). Thus, despite being inefficient in inducing cyclicity in postpartum cows, treatment with P4i promoted changes in ovarian dynamics and circulating profile of P4 that could serve as a basis for further studies and use strategies. Furthermore, the tested kit showed high potential for use in the quantification of circulating P4 in cattle. However, further tests and analyses of a larger number of samples are needed to confirm its robustness.

Resumption of cyclic ovarian activity in postpartum ewes: a review / Retorno da atividade ovariana cíclica pós-parto de ovelhas: uma revisão

The reproduction rate is considered a crucial factor that affects the ability of producers to meet the growing demand for ovines meat, and optimizing this factor will maximize the production rate and increase the efficiency of livestock. A reduction in the length of the postpartum anestrus period results in a shorter interval between lambing and conception and enables more lambs to be produced throughout the life of a ewe. This review discusses the current knowledge of several factors associated with the resumption of cyclic ovarian function in postpartum ewes and how the suckling management of ewes may affect this process. Factors that influence the resumption of cyclic ovarian activity include uterine involution, follicular development, occurrence of silent ovulation and short estrous cycles, breed, reproductive seasonality, nutrition and lactation. Controlled suckling and early weaning are management practices that may be used to obtain three lambings in a 24-month period. In the majority of the studies the interval between lambing and first estrus was reduced when a controlled suckling management strategy was used, therefore the controlled suckling appears to be the best alternative because it has produced good results and is easy to implement. Currently, however, this practice is still not widely used.(AU)

A taxa de reprodução é considerado um fator crucial que afeta a capacidade dos produtores em atender a crescente demanda por carne ovina e otimizar esse fator pode maximizar a taxa de produção e aumentar a eficiência da pecuária. A redução da duração do período de anestro pós-parto resulta em um intervalo menor entre a parição e concepção e permite que mais cordeiros sejam produzidos durante toda a vida de uma ovelha. Esta revisão discute o conhecimento atual de vários fatores associados com o retorno da função ovariana cíclica pós-parto em ovelhas e como o regime de amamentação de ovelhas podem afetar esse processo. Fatores que influenciam o retomada da atividade ovariana cíclica incluem involução uterina, o desenvolvimento folicular, a ocorrência de ovulação silênciosa e ciclos estrais curtos, raça, sazonalidade reprodutiva, nutrição e lactação. A amamentação controlada e o desmame precoce são práticas de manejo que podem ser utilizados para se obter três partos em um período de 24 meses. Na maioria dos estudos, o intervalo entre o parto e o primeiro estro foi reduzido quando o manejo de amamentação controlada foi utilizado, portanto, a amamentação controlada parece ser a melhor alternativa, pois tem apresentado bons resultados e sua implementação é fácil. Atualmente, no entanto, essa prática ainda não é amplamente utilizada.(AU)

Imunização anti-GnRH como um modelo para estudo da suplementação exógena de gonadotrofinas em fêmeas bovinas.

A suplementação de gonadotrofinas é necessária nas biotécnicas da reprodução. Em vacas no pós-parto, o uso de gonadotrofina coriônica equina (eCG) representa a única alternativa hormonal para estimular o crescimento folicular e aumentar as taxas de concepção. Alternativamente, o uso de FSH foi avaliado, porém, se mostrou ineficaz devido à curta meia-vida. Estudos utilizaram o modelo de vaca pós-parto para estudar a suplementação de gonatrofinas. Alternativamente, implantes com agonistas de GnRH permitem inibir a atividade ovariana, limitando o crescimento dos folículos até 4 mm de diâmetro. A imunocastração com a vacina comercial anti-GnRH (Bopriva®) também pode representar um modelo, porém, se torna necessário testar sua viabilidade. Portanto, objetivou-se validar um modelo para estudar fontes alternativas de suplementação com gonadotrofinas. No experimento 1, oito vacas cíclicas adultas, receberam a vacina anti-GnRH em duas doses com um intervalo de trinta dias. Em seguida, as vacas foram separadas em três grupos experimentais: Grupo 1: 400UI de eCG, grupo 2: 50 mg FSH+Pluronic F127 e grupo 3: 50 mg FSH, sendo realizada avaliação da dinâmica folicular. No Experimento 2, seis vacas foram selecionadas, três cíclicas (grupo controle) e três em anestro induzido pelo uso de vacina anti-GnRH (grupo Bopriva). No D0, as vacas cíclicas receberam um implante vaginal contendo 1 g de progesterona e 2 mg de benzoato de estradiol I.M., enquanto as vacas do grupo Bopriva não foram tratadas. Cinco dias após (D5), o tratamento com FSH (Folltropin) foi iniciado em todas as vacas, administrado em oito aplicações decrescentes com um intervalo de 12 h, totalizando 200 mg FSH por vaca. Nas vacas cíclicas, 500 µg de cloprostenol sódico foram administrados no D8, quando foram retirados os implantes vaginais. No Experimento 3, foram utilizadas seis vacas imunocastradas com duas doses da vacina anti-GnRH. No D0, as vacas receberam 830 UI de eCG e implante de 1g de progesterona. Quarenta e oito horas depois (D2), foi administrada outra dose de 830 UI de eCG. No D6,5 do experimento a ovulação foi induzida pela administração de 1250 UI de hCG. No D9, a ovulação foi avaliada e coletas de sangue foram realizadas no D6,5 até o D14, para mensurar as concentrações de progesterona. No experimento 1, todas as vacas responderam ao tratamento com a vacina anti GnRH, observando-se apenas folículos com diâmetro inferior a 4 mm, mostrando eficácia da vacina. Porém, nenhum dos tratamentos com dose única induziu o crescimento folicular. No Experimeno 2, todas as vacas responderam ao protocolo de superovulação com FSH, apresentando múltiplos folículos > 8 mm, comprovando a reversão do efeito vacinal. No experimento 3, após a segunda aplicação de eCG, quatro vacas responderam ao tratamento com pelo menos um folículo > 10 mm. Vacas que apresentaram folículos pré-ovulatórios responderam ao tratamento com hCG e ovularam, apresentando concentrações de progesterona acima de 20 ng/mL sete dias após o tratamento, demonstrando a funcionalidade dos corpos lúteos. Portanto, conclui-se que a imunocastração com vacina anti-GnRH pode ser utilizada como modelo para o estudo de alternativas para a suplementação exógena de gonadotrofinas em fêmeas bovinas.

Gonadotropin supplementation is necessary in reproductive biotechnics. In postpartum cows, the use of equine chorionic gonadotropin (eCG) represents the only hormonal alternative to stimulate follicular growth and increase conception rates. Alternatively, the use of FSH was evaluated, however, it was shown to be ineffective due to the short half-life. Studies used the postpartum cow model to study gonatrophin supplementation. Alternatively, implants with GnRH agonists allow to inhibit ovarian activity, limiting the growth of follicles up to 4 mm in diameter. Immunocastration with the commercial anti-GnRH vaccine (Bopriva) can also represent a model, however, it becomes necessary to test its viability. Therefore, the objective was to validate a model to study alternative sources of gonadotropin supplementation. In experiment 1, eight adult cyclic cows received the anti-GnRH vaccine in two doses with an interval of thirty days. Then, the cows were separated into three experimental groups: Group 1: 400UI of eCG, group 2: 50 mg FSH+Pluronic F127 and group 3: 50 mg FSH, with an evaluation of the follicular dynamics. In Experiment 2, six cows were selected, three cyclic (control group) and three in anestrus induced by the use of anti-GnRH vaccine (Bopriva group). On D0, cyclic cows received a vaginal implant containing 1 g of progesterone and 2 mg of estradiol benzoate, while cows in the Bopriva group were not treated. Five days later (D5), treatment with FSH (Folltropin) was started in all cows, administered in eight decreasing applications with an interval of 12 h, totaling 200 mg FSH per cow. In cyclic cows, 500 µg of sodium cloprostenol was administered on D8, when the vaginal implants were removed. In Experiment 3, six cows were immunocastrated with two doses of the anti-GnRH vaccine. On D0, the cows received 830 IU of eCG and 1g of progesterone implant. Forty-eight hours later (D2), another dose of 830 IU of eCG was administered. On D6.5 of the experiment, ovulation was induced by administering 1250 IU of hCG. On D9, ovulation was assessed and blood samples were taken from D6.5 to D14 to measure progesterone concentrations. In experiment 1, all cows responded to treatment with the anti-GnRH vaccine, observing only follicles with a diameter less than 4 mm, showing the effectiveness of the vaccine. However, none of the singledose treatments induced follicular growth. In Experiment 2, all cows responded to the FSH superovulation protocol, presenting multiple follicles > 8 mm, proving the reversal of the vaccine effect. In experiment 3, after the second application of eCG, four cows responded to treatment with at least one follicle > 10 mm. Cows that presented preovulatory follicles responded to treatment with hCG and ovulated, with progesterone concentrations above 20 ng/mL seven days after treatment, demonstrating the functionality of the corpus luteum. Therefore, it is concluded that immunocastration with anti-GnRH vaccine can be used as a model for the study of alternatives for exogenous gonadotropin supplementation in female bovine animals.

New approaches to treatment of infertility in the bitch / Novas abordagens ao tratamento de infertilidade em cadelas

Infertility in the bitch has manifold causes. Bacterial endometritis was found to be causative in most cases and since the incidence of B.canis infection in breeding bitches is increasing, serology for B.canis should always be performed. In subclinical or low grade cases of other bacterial infections, conservative treatment may be successful with the repeated application of the antiprogesterone aglepristone and synthetic prostaglandins. Another frequent cause is primary anoestrus or secondary anestrus. Both conditions can be caused by multiple diseases, organ dysfunctions and even medicaments. Treatment of the cause is mostly successful, however, induction of oestrus can be successful in single cases. The GnRH implant deslorelin proved to be useful when implanted in anestrus; resulting pregnancy rates excceded 70%; however, as a side effect, luteal failure may occur. Cystic degenerative and inflammatory conditions of the uterus may cause infertility, resorption or abortion. Diagnosis can be improved by cytological, bacteriological and histological examination of uterine specimens but the risk of endometritis and pyometra has to be considered. Treatment with the antiprogesterone aglepristone and broad spectrum antibiotics is recommended. Abnormalities of the vulva, vestibule and vagina as well as genetical disorders of sexual development are very seldom but should be excluded by a thorough gynaecological examination prior to first breeding. Hormonal imbalances like luteal deficiency and hypothyroidism can be primary or caused by other diseases and should be considered in case of repeated failure of pregnancy. During pregnancy, dietary substitution of folic acid is important to prevent neonatal cleft palate. However, feeding tyrosine during oestrus did not improve copulation behaviour.(AU)

Existem diversas causas de infertilidade em cadelas. Endometriose bacteriana tem provado ser a causa na maioria dos casos e como a incidência de infecção com B. canis em cadelas de reprodução está aumentando, a sorologia para B. canis sempre deve ser realizada. Em casos subclínicos ou de baixo grau de outras infecções bacterianas o tratamento conservador pode ter sucesso com a aplicação repetida de antiprogesterona aglepristone e prostaglandinas sintéticas. Outra causa frequente é o anestro primário ou secundário. Ambas as condições podem ser causadas por diversas doenças, disfunções em órgãos e até mesmo medicamentos. O tratamento da causa geralmente tem sucesso, porém, a indução de estro pode ser bem sucedida em casos individuais. O implante GnRH deslorelina provou ser útil quando implantado no anestro, resultando em taxas de gestação acima de 70%; porém, como efeito colateral, falha lútea pode ocorrer. Condições císticas degenerativas e inflamatórias do útero podem causar infertilidade, reabsorção ou aborto. O diagnostico pode ser melhorado por exame citológico, bacteriológico e histológico de amostras do útero, mas o risco de endometriose e piometria deve ser considerado. O tratamento com antiprogesterona aglepristone e antibióticos de grande espectro é recomendado. Anormalidades da vulva, vestíbulo e vagina, além de distúrbios genéticos de desenvolvimento sexual são raros, mas devem ser excluídos através de exame ginecológico antes da primeira reprodução. Desequilíbrios hormonais como deficiência lútea e hipotireoidismo podem ser primários ou causados por outras doenças e devem ser considerados no caso de falha repetida de gestação. Durante a gestação a substituição de ácido fólico na dieta é importante para prevenir fenda palatina neonatal. Porém, a alimentação com tirosina durante o estro não melhorou o comportamento reprodutor.(AU)