Antral follicle count, productive and reproductive parameters in Bos indicus and Bos indicus-taurus prepubertal heifers with early puberty induction / Contagem de folículos antrais, parâmetros produtivos e reprodutivos em novilhas pré-púberes Bos indicus e Bos indicus-taurus com indução precoce de puberdade

Prepubertal Nelore (G-N = 15) and crossbred Nelore x Aberdeen Angus heifers (G-NA = 15) were used for this study. AFC, live weight, body condition score (BCS), ovary and dominant follicle (DF) diameters were determined in each animal. Puberty induction was performed by insertion of a 4th use progesterone device (D0) which was removed on D12. Also, 1 mg estradiol benzoate was administered, and estrus intensity was classified (D12). At D21, the presence and diameter of the corpus luteum (CL) were registered. AFC was highly repeatable, regardless of hormone induction in both G-N (r=0.79) and G-NA (r=0.90). The mean AFC was greater in G-N compared to G-NA (24.2±8.5 vs. 17.7±9.0 follicles). A variation in BCS throughout the study occurred in G-NA, but not in G-N. The average weight gain (AWG) was greater in G-NA compared to G-N (0.69±0.33 vs. 0.40±0.29kg/day). The G-NA resulted in a larger diameter of DF at D12 than G-N (11.6±2.7 vs. 9.3±1.5mm). In conclusion, AFC was greater in Nelore heifers, although in both breeds this count was highly repeatable during puberty induction. Crossbred heifers had greater BCS and AWG with greater diameter of DF, indicating higher precocity when compared to Nelore heifers.

Novilhas pré-púberes Nelore (G-N=15) e mestiças Nelore x Aberdeen Angus (G-NA=15) foram utilizadas neste estudo. CFA, peso vivo, escore de condição corporal (ECC), diâmetros do ovário e folículo dominante (FD) foram determinados em cada animal. A indução da puberdade foi realizada pela inserção de um dispositivo de progesterona de quarto uso (D0), que foi retirado no D12. Além disso, 1mg de benzoato de estradiol foi administrado e a intensidade do estro foi classificada (D12). No D21, foram registrados a presença e o diâmetro do corpo lúteo (CL). A CFA foi altamente repetível, independentemente da indução hormonal em G-N (r=0,79) e G-NA (r=0,90). A CFA média foi maior em G-N em comparação com G-NA (24,2±8,5 vs. 17,7±9,0 folículos). Uma variação no ECC ao longo do estudo ocorreu em G-NA, mas não em G-N. O ganho de peso médio (GPM) foi maior em G-NA em comparação com G-N (0,69±0,33 vs. 0,40±0,29kg/dia). O G-NA resultou em um diâmetro maior de FD em D12 do que o G-N (11,6±2,7 vs. 9,3±1,5mm). Em conclusão, a CFA foi maior em novilhas Nelore, embora em ambas as raças essa contagem tenha sido altamente repetível durante a indução da puberdade. Novilhas mestiças apresentaram maior ECC e GPM com maior diâmetro de FD, indicando maior precocidade quando comparadas às novilhas Nelore.

Is the number of antral follicles an interesting selection criterium for fertility in cattle?

Recent studies indicate that the antral follicle population may be of paramount importance to improve reproductive performance in cows. There is already an agreement that the antral follicle count (AFC; follicles ≥3 mm in diameter) is a highly variable trait among animals, but with high repeatability in the same individual. Thus, females can be classified into low, intermediate or high AFC. Several studies in Bos taurus show a positive correlation between AFC and fertility parameters, such as increased quantity and quality of embryos, better pregnancy rates, higher progesterone levels, among others. However, there is still no consensus on AFC in Bos indicus females and indicus-taurus. This article aims to discuss the main aspects related to the population of antral follicles and its relation to the reproductive performance associated with the most common techniques in assisted reproduction (timed artificial insemination, in vitro embryo production, embryo transfer and superovulation).(AU)

Is the number of antral follicles an interesting selection criterium for fertility in cattle?

Recent studies indicate that the antral follicle population may be of paramount importance to improve reproductive performance in cows. There is already an agreement that the antral follicle count (AFC; follicles ≥3 mm in diameter) is a highly variable trait among animals, but with high repeatability in the same individual. Thus, females can be classified into low, intermediate or high AFC. Several studies in Bos taurus show a positive correlation between AFC and fertility parameters, such as increased quantity and quality of embryos, better pregnancy rates, higher progesterone levels, among others. However, there is still no consensus on AFC in Bos indicus females and indicus-taurus. This article aims to discuss the main aspects related to the population of antral follicles and its relation to the reproductive performance associated with the most common techniques in assisted reproduction (timed artificial insemination, in vitro embryo production, embryo transfer and superovulation).

Biomarcadores fisiológicos de ovelhas (Ovis aries) mestiças durante o periparto / Physiological biomarkers of crossbred sheep (Ovis aries) during peripartum

O objetivo do presente estudo foi verificar as variações nos constituintes do leucograma e doeritrograma no periparto de fêmeas ovinas da região norte do Paraná. Ovelhas mestiças (n = 9) foram submetidasà venopunção a cada 24 h nos cinco dias antecedentes ao parto, no momento do parto, 12 h, um, dois, três,quatro, oito e 16 dias pós-parto. As amostras foram coletadas em tubos contendo EDTA, e foram feitas asseguintes análises: volume globular (VG), hemoglobina (HB), hemácias (HE), volume corpuscular médio(VCM), concentração de hemoglobina corpuscular média (CHCM), hemoglobina corpuscular média (HCM),Red Cell Distribution Width (RDW) e contagem total e diferencial dos leucócitos. Os dados foram avaliados poranálise estatística descritiva e evidenciaram que os períodos gestacional e puerperal exercem influência sobre operfil leucocitário de ovelhas com predomínio de neutrófilos próximo do parto, no momento do parto e 12 h pósparto.O eritrograma não demonstrou grandes variações no transcorrer do experimento.(AU)

The aim of this study was to determine the variations in the constituents of the erythrocyte and leukocytecount in the peripartum female sheep of northern Paraná. Crossbred ewes (n = 9) underwent venipuncture every24 h in the five days prior to birth, in the moment of birth, and 12 h, 1, 2, 3, 4, 8 and 16 days postpartum. Thesamples were collected in EDTA tubes and the following analyzes were performed: Globular Volume (VG),Hemoglobin (Hb), Red Blood Cells (HE), Mean Corpuscular Volume (VCM), Mean Corpuscular HemoglobinConcentration (CHCM), Mean Corpuscular Hemoglobin (HCM), Red Cell Distribution Width (RDW), and totalcount and differential leukocyte. The data were analyzed with descriptive statistical analysis and showed thatpregnancy and puerperal influence on leukocyte profile of sheep with a predominance of neutrophil next of birth,in the moment of birth and 12 h postpartum. The hematological values showed no significant variations duringthe experiment.and 12 h postpartum. The hematological values showed no significant variations during theexperiment.(AU)

Biomarcadores fisiológicos de ovelhas (Ovis aries) mestiças durante o periparto / Physiological biomarkers of crossbred sheep (Ovis aries) during peripartum

O objetivo do presente estudo foi verificar as variações nos constituintes do leucograma e doeritrograma no periparto de fêmeas ovinas da região norte do Paraná. Ovelhas mestiças (n = 9) foram submetidasà venopunção a cada 24 h nos cinco dias antecedentes ao parto, no momento do parto, 12 h, um, dois, três,quatro, oito e 16 dias pós-parto. As amostras foram coletadas em tubos contendo EDTA, e foram feitas asseguintes análises: volume globular (VG), hemoglobina (HB), hemácias (HE), volume corpuscular médio(VCM), concentração de hemoglobina corpuscular média (CHCM), hemoglobina corpuscular média (HCM),Red Cell Distribution Width (RDW) e contagem total e diferencial dos leucócitos. Os dados foram avaliados poranálise estatística descritiva e evidenciaram que os períodos gestacional e puerperal exercem influência sobre operfil leucocitário de ovelhas com predomínio de neutrófilos próximo do parto, no momento do parto e 12 h pósparto.O eritrograma não demonstrou grandes variações no transcorrer do experimento.

The aim of this study was to determine the variations in the constituents of the erythrocyte and leukocytecount in the peripartum female sheep of northern Paraná. Crossbred ewes (n = 9) underwent venipuncture every24 h in the five days prior to birth, in the moment of birth, and 12 h, 1, 2, 3, 4, 8 and 16 days postpartum. Thesamples were collected in EDTA tubes and the following analyzes were performed: Globular Volume (VG),Hemoglobin (Hb), Red Blood Cells (HE), Mean Corpuscular Volume (VCM), Mean Corpuscular HemoglobinConcentration (CHCM), Mean Corpuscular Hemoglobin (HCM), Red Cell Distribution Width (RDW), and totalcount and differential leukocyte. The data were analyzed with descriptive statistical analysis and showed thatpregnancy and puerperal influence on leukocyte profile of sheep with a predominance of neutrophil next of birth,in the moment of birth and 12 h postpartum. The hematological values showed no significant variations duringthe experiment.and 12 h postpartum. The hematological values showed no significant variations during theexperiment.

Insemination of four cows per dose of frozen semen with a fixed-time artificial insemination protocol

The aim of the study was to evaluate the practicality of a 1: 4 dilution of doses of semen in fixed - time artificial insemination ( FTAI ) programs. Nelore cows (n = 803 ) were synchronized by a conventional FTAI protocol. For AI in the dilut ed group (n = 392) , 0.5 ml semen straws were thawed and 0.5 ml of extender conta ining amino acids and methylxanthine derivatives was added. The straws were fractionated into four straws of 0.25 ml each (dilution 1:4) with approximately 2.5 x 10 6 spermatozoa each and the insemination was performed in the ipsilateral horn to the ovary c ontaining the dominant follicle . In the control group (n = 411), AI was performed in the uterine body with one straw of 0.5 ml (10 x 10 6 spermatozoa) containing seme n from the same bull and batch . The conception rate was 49.2% (193/392) for the diluted gro up and 50.1% (206/411) for the control group, with 1.97 and 0.50 pregnancies per dose of semen , respectively . T he dilution of semen provide d a pregnancy index similar to the control group ; however, the technique increased the number of pregnancies per dos e , allowing for the best use of semen of high genetic value and reducing the cost per pregnancy.

Ovarian follicle reserve: emerging concepts and applications

This paper presents new concepts in the study of folliculogenesis and describes some of the current applications to reproductive biotechnology. The importance of better understanding this issue is addressed both for basic and applied research. After a brief review of the basic conceptions of the origin, formation, and growth of follicules according to stablished concepts, some controversial points, as the postnatal production of the follicles and the role of multioocyte follicles, are discussed. The importance of the ovarian follicular reserve is considered for fertility and reproductive parameters, as well as some questiones about the presence of multioocyte follicles in adult ovaries. Finally, some future prospects are proposed.

Insemination of four cows per dose of frozen semen with a fixed-time artificial insemination protocol

The aim of the study was to evaluate the practicality of a 1: 4 dilution of doses of semen in fixed - time artificial insemination ( FTAI ) programs. Nelore cows (n = 803 ) were synchronized by a conventional FTAI protocol. For AI in the dilut ed group (n = 392) , 0.5 ml semen straws were thawed and 0.5 ml of extender conta ining amino acids and methylxanthine derivatives was added. The straws were fractionated into four straws of 0.25 ml each (dilution 1:4) with approximately 2.5 x 10 6 spermatozoa each and the insemination was performed in the ipsilateral horn to the ovary c ontaining the dominant follicle . In the control group (n = 411), AI was performed in the uterine body with one straw of 0.5 ml (10 x 10 6 spermatozoa) containing seme n from the same bull and batch . The conception rate was 49.2% (193/392) for the diluted gro up and 50.1% (206/411) for the control group, with 1.97 and 0.50 pregnancies per dose of semen , respectively . T he dilution of semen provide d a pregnancy index similar to the control group ; however, the technique increased the number of pregnancies per dos e , allowing for the best use of semen of high genetic value and reducing the cost per pregnancy.(AU)

Ovarian follicle reserve: emerging concepts and applications

This paper presents new concepts in the study of folliculogenesis and describes some of the current applications to reproductive biotechnology. The importance of better understanding this issue is addressed both for basic and applied research. After a brief review of the basic conceptions of the origin, formation, and growth of follicules according to stablished concepts, some controversial points, as the postnatal production of the follicles and the role of multioocyte follicles, are discussed. The importance of the ovarian follicular reserve is considered for fertility and reproductive parameters, as well as some questiones about the presence of multioocyte follicles in adult ovaries. Finally, some future prospects are proposed.(AU)

Multioocyte follicles in adult mammalian ovaries

The majority of follicles contain only a single oocyte. However, it has been shown that more than two oocytes can exist within the same follicle. These follicles have been well documented during fetal development, but their presence in adult ovaries is an intriguing physiologic phenomenon. Apoptotic pathway members, locally produced factors, circulating hormones and steroid factors may be involved in their persistence. The origin and fate of these structures, as well as their contribution to ovulation and fertility in adult females, are discussed in this review.

Multioocyte follicles in adult mammalian ovaries

The majority of follicles contain only a single oocyte. However, it has been shown that more than two oocytes can exist within the same follicle. These follicles have been well documented during fetal development, but their presence in adult ovaries is an intriguing physiologic phenomenon. Apoptotic pathway members, locally produced factors, circulating hormones and steroid factors may be involved in their persistence. The origin and fate of these structures, as well as their contribution to ovulation and fertility in adult females, are discussed in this review.(AU)

Reproductive performance of ewes treated with an estrus induction/synchronization protocol during the spring season

The aim of this study was to evaluate the reproductive performance of ewes treated with eCG and an exogenous progestagen protocol during the spring season. Forty - eight mixed - breed wool and hair ewes ( body condition score of 2.8 ± 0.5 and 41 ± 3 kg ) were randomly assigned into two groups ( n = 24/group), which received (G - Sync) or not (G - Control) an intravaginal device ( Day 0) containing 60 mg of medroxyprogesterone acetate. On D ay 7, ewes of the G - Sync were injected with 300 IU of eCG and 30 ug of d - C loprostenol, im . On D ay 9, the device was removed and 12 h later males were introduced into the G - Sync and G - Control groups in a proportion of 1:6. Estrus response observation and mating were performed during D ays 10, 11 and 12 from 7 to 9 AM and 4 to 6 PM. After D ay 12, males were s eparated from females for 10 days and later reintroduced into the flock for 45 days. Estrus rates for the G - Control and G - Sync group s during D ays 10, 11 and 12 were 4 and 88 % (P < 0.05) , respectively . Pregnancy rates fr om initial mating on D ays 10, 11 and 12 were 0 (G - Control) and 4 6% (G-Sync;P < 0.05). Total pregnancy rates for the whole mating season were 50 (G-Control) and 79% (G-Sync;P< 0.05). The exogenous progestagen protocol plus eCG used for estrus induction/s ynchronization improved the pregnancy rate of mixed-breed wool and hair ewes by about 29% points at the end of the breeding season. Thus, this procedure seems to be appropriate to be implemented as part of the reproductive management of some ovine farms during the non-breeding season.

Reproductive performance of ewes treated with an estrus induction/synchronization protocol during the spring season

The aim of this study was to evaluate the reproductive performance of ewes treated with eCG and an exogenous progestagen protocol during the spring season. Forty - eight mixed - breed wool and hair ewes ( body condition score of 2.8 ± 0.5 and 41 ± 3 kg ) were randomly assigned into two groups ( n = 24/group), which received (G - Sync) or not (G - Control) an intravaginal device ( Day 0) containing 60 mg of medroxyprogesterone acetate. On D ay 7, ewes of the G - Sync were injected with 300 IU of eCG and 30 ug of d - C loprostenol, im . On D ay 9, the device was removed and 12 h later males were introduced into the G - Sync and G - Control groups in a proportion of 1:6. Estrus response observation and mating were performed during D ays 10, 11 and 12 from 7 to 9 AM and 4 to 6 PM. After D ay 12, males were s eparated from females for 10 days and later reintroduced into the flock for 45 days. Estrus rates for the G - Control and G - Sync group s during D ays 10, 11 and 12 were 4 and 88 % (P < 0.05) , respectively . Pregnancy rates fr om initial mating on D ays 10, 11 and 12 were 0 (G - Control) and 4 6% (G-Sync;P < 0.05). Total pregnancy rates for the whole mating season were 50 (G-Control) and 79% (G-Sync;P< 0.05). The exogenous progestagen protocol plus eCG used for estrus induction/s ynchronization improved the pregnancy rate of mixed-breed wool and hair ewes by about 29% points at the end of the breeding season. Thus, this procedure seems to be appropriate to be implemented as part of the reproductive management of some ovine farms during the non-breeding season.(AU)

Effect of indole acetic acid on the in vitro activation and survival of bovine (Bos indicus) preantral follicles

The objective of this study was to evaluate the development of preantral follicles from the Nelore breed of Bos indicus after in vitro culture of ovarian cortices in different concentrations of indole acetic acid (IAA). In addition, this study investigated the possible association of mammalian genes with IAA activity in bovine preantral follicles using an in silico approach. Ovaries (N = 8) from Nelore heifers were collected, and the ovarian cortex was divided into 14 fragments were cultured individuallu for two or siz days in Minimum Essential Medium (MEM) with 0, 10, 40, 100, 500 or 1000 ng/ml of IAA. Follicles were classified as primordial or as developing (primary and secondary) follicles. The in silico approach to search for auxinresponsive candidate genes was performed with bioinformaties tools, such as GenBank and SWISS-PROT database, Kyoto Encyclopedia of Genes and Genomes (KEGG) and the Clustal W program. Compared to the control culture, the percentage of primordial follicles was reduced (P < 0,05) and the percentage of developing follicles was increased ( P < 0,05) after 2 or 6 days of culture in all media tested. Furtherimore, culture of the ovarian cortex for 6 days reduced the percentage of healthy, morphologically normal follicles when compared with the control (P < 0,05). In contrast, cultures supplemented with 10 ng/ml of IAA were the only samples that had similar (P < 0,05) percentages relative to the control group. Finally, we found a mammalian gene that was homologous to the plant gene, ROOTY, which may be involved in the oocyte response to IAA. We conclude that the 10 ng/ml concentration of IAA promoted follicular survival and activation of nelore bovine preantral follicles after 6 days of culture in vitro.(AU)

Effect of indole acetic acid on the in vitro activation and survival of bovine (Bos indicus) preantral follicles

The objective of this study was to evaluate the development of preantral follicles from the Nelore breed of Bos indicus after in vitro culture of ovarian cortices in different concentrations of indole acetic acid (IAA). In addition, this study investigated the possible association of mammalian genes with IAA activity in bovine preantral follicles using an in silico approach. Ovaries (N = 8) from Nelore heifers were collected, and the ovarian cortex was divided into 14 fragments were cultured individuallu for two or siz days in Minimum Essential Medium (MEM) with 0, 10, 40, 100, 500 or 1000 ng/ml of IAA. Follicles were classified as primordial or as developing (primary and secondary) follicles. The in silico approach to search for auxinresponsive candidate genes was performed with bioinformaties tools, such as GenBank and SWISS-PROT database, Kyoto Encyclopedia of Genes and Genomes (KEGG) and the Clustal W program. Compared to the control culture, the percentage of primordial follicles was reduced (P < 0,05) and the percentage of developing follicles was increased ( P < 0,05) after 2 or 6 days of culture in all media tested. Furtherimore, culture of the ovarian cortex for 6 days reduced the percentage of healthy, morphologically normal follicles when compared with the control (P < 0,05). In contrast, cultures supplemented with 10 ng/ml of IAA were the only samples that had similar (P < 0,05) percentages relative to the control group. Finally, we found a mammalian gene that was homologous to the plant gene, ROOTY, which may be involved in the oocyte response to IAA. We conclude that the 10 ng/ml concentration of IAA promoted follicular survival and activation of nelore bovine preantral follicles after 6 days of culture in vitro.

Epigenética e neo-oogênese: novos conceitos em foliculogênese / Epigenetic and neo-oogenesis: new concepts on folliculogenesis

Novas teorias têm sido propostas sobre a origem e o crescimento dos gametas femininos, desafiando conceitos de mais de 150 anos. A possibilidade de formação contínua de folículos e ovócitos apresenta-se como hipótese extremamente interessante, mas requer ainda novos trabalhos, seja para comprovar sua existência ou refutá-la definitivamente. O estudo da epigenética surge como grande possibilidade para uma melhor compreensão dessas teorias. As variações epigenéticas são dinâmicas, transmitidas entre gerações e guardam relação com o ambiente. O estoque finito de oócitos, a renovação contínua, ou a coexistência de ambos são discutidos neste artigo.(AU)

New theories have been proposed for the origin and growth of female gametes, challenging concepts of more than 150 years. The possibility of continue formation of follicles and oocytes appears to be very interesting hypothesis, but it still need further works, either to definitely prove or refute its existence. The study of epigenetic comes as a remarkable possibility for a better understanding of these theories. The epigenetic changes are dynamic, passed down between generations and are related with environment. The finite stock of oocytes, the continuous renewal, or co-existence of both are discussed in this paper.(AU)

Epigenética e neo-oogênese: novos conceitos em foliculogênese / Epigenetic and neo-oogenesis: new concepts on folliculogenesis

Novas teorias têm sido propostas sobre a origem e o crescimento dos gametas femininos, desafiando conceitos de mais de 150 anos. A possibilidade de formação contínua de folículos e ovócitos apresenta-se como hipótese extremamente interessante, mas requer ainda novos trabalhos, seja para comprovar sua existência ou refutá-la definitivamente. O estudo da epigenética surge como grande possibilidade para uma melhor compreensão dessas teorias. As variações epigenéticas são dinâmicas, transmitidas entre gerações e guardam relação com o ambiente. O estoque finito de oócitos, a renovação contínua, ou a coexistência de ambos são discutidos neste artigo.

New theories have been proposed for the origin and growth of female gametes, challenging concepts of more than 150 years. The possibility of continue formation of follicles and oocytes appears to be very interesting hypothesis, but it still need further works, either to definitely prove or refute its existence. The study of epigenetic comes as a remarkable possibility for a better understanding of these theories. The epigenetic changes are dynamic, passed down between generations and are related with environment. The finite stock of oocytes, the continuous renewal, or co-existence of both are discussed in this paper.

Reproductive performance of ewes mated in the spring when given nutritional supplements to enhance energy levels

The objective of this study was to evaluate the reproductive performance of ewes mated in the spring when given nutritional supplements to enhance energy levels. Ewes were assessed for weight and body condition at the beginning and end of flushing periods. Lambing rates and rates of proliferation were also evaluated. Crossbred woolly ewes (n = 46), 36 ± 2 months of age and rated 3.0 ± 0.1 on a body condition scale that spanned from 1 to 5 were divided into four treatment groups. One group received no feed supplements (NFS), while the others were supplemented for 64 days: 21 days before and 43 days during the mating season. The latter groups were fed soybean hulls at 0.6% (S06), 0.9% (S09) and 1.2% (S12) of their body weight (BW), calculated using dry mass. Ewes were mated for 50 days with four rams by means of natural breeding in October and November, which is spring in Brazil. There was no significant difference among the treatments based on mean BW of the ewes before and after the supplementation period (P > 0.05). Similarly, no differences were found in the rates of proliferation (P > 0.05). The S09 treatment presented the highest lambing rate (82%, 9/11), while the NFS treatment correlated with the lowest rate (42%, 5/12; P < 0.05). There was a positive linear effect for body condition score as the supplementation level increased (P < 0.05). We conclude that a supplementation level of 0.9% BW seems to improve lambing rates for ewes that undergo springtime mating.(AU)

Reproductive performance of ewes mated in the spring when given nutritional supplements to enhance energy levels

The objective of this study was to evaluate the reproductive performance of ewes mated in the spring when given nutritional supplements to enhance energy levels. Ewes were assessed for weight and body condition at the beginning and end of flushing periods. Lambing rates and rates of proliferation were also evaluated. Crossbred woolly ewes (n = 46), 36 ± 2 months of age and rated 3.0 ± 0.1 on a body condition scale that spanned from 1 to 5 were divided into four treatment groups. One group received no feed supplements (NFS), while the others were supplemented for 64 days: 21 days before and 43 days during the mating season. The latter groups were fed soybean hulls at 0.6% (S06), 0.9% (S09) and 1.2% (S12) of their body weight (BW), calculated using dry mass. Ewes were mated for 50 days with four rams by means of natural breeding in October and November, which is spring in Brazil. There was no significant difference among the treatments based on mean BW of the ewes before and after the supplementation period (P > 0.05). Similarly, no differences were found in the rates of proliferation (P > 0.05). The S09 treatment presented the highest lambing rate (82%, 9/11), while the NFS treatment correlated with the lowest rate (42%, 5/12; P < 0.05). There was a positive linear effect for body condition score as the supplementation level increased (P < 0.05). We conclude that a supplementation level of 0.9% BW seems to improve lambing rates for ewes that undergo springtime mating.

Efeito da concentração de ácido 3-indol-acético na ativação e crescimento in vitro de folículos pré-antrais ovinos / Effect of indol acetic acid concentration in the activation and growth of ovine preantral follicles

Avaliou-se o desenvolvimento de folículos pré-antrais ovinos após o cultivo in vitro do córtex ovariano em várias concentrações de ácido 3-indol acético (IAA). O córtex ovariano foi dividido em fragmentos de aproximadamente 3×3mm. Um fragmento foi imediatamente fixado em Bouin (controle dia 0) e os demais destinados ao cultivo por dois ou seis dias em meio essencial mínimo (MEM+) acrescido de 10, 40, 100, 500 ou 1000ng/ml de IAA. Após o cultivo in vitro, não houve variação entre folículos dos tratamentos e folículos-controle, exceto nos suplementados com 40ng/ml de IAA. Nestes observaram-se redução de folículos primordiais e aumento de folículos em desenvolvimento (P<0,05). Em relação aos folículos do grupo-controle, houve redução de pré-antrais normais no cultivo de seis dias (P<0,05). Após dois dias de cultivo, a redução foi observada somente nos folículos suplementados com 500 ou 1000ng/ml de IAA. Folículos pré-antrais ovinos podem ser ativados in vitro com sucesso após o cultivo em MEM+ suplementado com 40ng/ml de IAA.(AU)

The development of ovine preantral follicles after in vitro culture of ovarian cortex in various concentrations of indol acetic acid (IAA) was evaluated. The ovarian cortex was divided into fragments of approximately 3×3mm. One fragment was immediately fixed in Bouin (control day 0) whereas the other fragments were cultured for two or six days in minimum essential medium (MEM) supplemented (MEM+) with 10, 40, 100, 500 or 1000ng/ml of IAA. After six days of in vitro culture the percentage of primordial and developing follicles remained unaltered when compared to control follicles, except for MEM+ added of 40ng/ml of IAA that presented reduction of primordial follicles and increase of developing follicles (P<0.05). The culture of ovarian cortex for six days, in all tested media, reduced the percentages of healthy follicles when compared to control follicles (P<0.05). After two days of culture this reduction was only observed in the follicles treated with 500 or 1000ng/ml of IAA. Ovine primordial follicles may be successfully activated in vitro after culturing in MEM+ containing 40ng/ml of IAA.(AU)