Definition of protocols for cryopreservation and three-dimensional in vitro culture of prepubertal goat testicular tissue after histomorphological, ultrastructural, and functional analysis.

This study aims to define the best method (slow freezing or vitrification) and fragment size (1, 5, or 9 mm³) for prepubertal goat testis cryopreservation, as well as to evaluate testicular morphological integrity after cryopreservation and in vitro culture (IVC). Initially (experiment I), 1, 5, or 9 mm³ testis fragments were cryopreserved by slow freezing using a Mr. Frosty container with 20% Dimethylsulfoxide (DMSO) or vitrified using the Ovarian Tissue Cryosystem (OTC) device, (Equilibration solution - ES: 10% DMSO and 10% ethylene glycol - EG; Vitrification solution - VS: 20% DMSO and 20% EG) and then subjected to morphological analysis, type I and III collagen quantification and gene expression (Oct4, C-kit, Bax, and Bcl-2). Subsequently, (experiment II), fresh or cryopreserved by slow freezing testis fragments were cultured in vitro and submitted to morphological analysis by scanning electron microscopy. The data from the experiment I revealed fewer morphological alterations in 1 and 5 mm³ fragments after vitrification and slow freezing, respectively. The percentage of type I collagen fibers in 5 and 9 mm³ frozen was higher than in fresh or vitrified fragments. For type III collagen, fresh or frozen fragments of 1 and 5 mm3 showed a higher percentage than fragments of 9 mm3. Gene expression for Oct4 and C-kit after slow freezing or vitrification in the 5 mm3 fragments was lower than that observed in the fresh fragments. The Bax:Bcl-2 ratio in the 1 and 9 mm³ fragments was lower than in the 5 mm³ fragments for fresh fragments or after freezing. In experiment II, fragments cultured in vitro, previously frozen or not, showed more morphological alterations than fresh or frozen fragments. We concluded that slow freezing of 5 mm³ fragments was the best protocol for cryopreserving prepubertal goat testis and although the results of IVC are encouraging, it still needs improvement to restore testicular function after cryopreservation.

In vitro embryo production from early antral follicles of goats fed with a whole full-fat linseed based diet.

The present study aimed to use an in vitro follicle culture (IVFC) biotechnique as a tool to evaluate the influence of whole flaxseed as a feed supplementation in the diet on the in vitro development of caprine early antral follicles (EAFs) and further embryo production. In total, 18 adult goats were homogeneously allocated into two diet groups: Control and Flaxseed. EAFs from both experimental groups (300-400 µm) were isolated and cultured in vitro for 18 days. After IVFC, recovered cumulus-oocyte complexes were submitted to in vitro maturation, and subsequently to IVF and in vitro embryo culture. The endpoints evaluated were follicular growth and morphology, oocyte recovery rate and diameter, sperm penetration, pronuclei formation, embryo development, and estradiol production. The addition of the whole flaxseed in the diet did not affect (P > 0.05) follicular growth and diameter. A higher (P < 0.05) percentage of oocytes ≥ 110 µm was recovered from the flaxseed treatment. However, the sperm penetration rate was higher (P < 0.05) in the control treatment when compared with the flaxseed treatment, but no differences were found regarding the rate of fertilization nor cleaved embryos. In conclusion, dietary flaxseed increased the recovery rate of fully grown oocytes, but it did negatively affect the sperm penetration rate, even though there was no further effect on the cleavage rate.

Metabolic stress and reproductive features in post-partum goats supplemented for a long period with detoxified castor meal as the source of dietary nitrogen / Estresse metabólico e características reprodutivas em cabras pós-parto suplementadas por longo período com mamona desintoxicada como fonte de nitrogênio na dieta

This study evaluated the effect of detoxified castor meal on the reproductive performance, metabolic stress, milk production, and kid development in peripartum goats. The diet of the animals were with (DCM, n= 20) or without (WDCM, n= 21) detoxified castor meal during the entire gestation and until weaning, 60 days post-birth. No differences were observed in the gestation period, litter size, rate of multiple births, and mortality between the two groups. The postpartum plasma concentrations of progesterone remained below 1ng/mL in all animals, thus, confirming the absence of active corpora lutea. The thickness of sternum adipose tissue and loin area, levels of urea and cholesterol, milk production, and daily weight gain in the kids were low in the DCM group when compared to those in the WDCM group (P< 0.05). To conclude, the use of detoxified castor meal in peripartum goats resulted in lower level of performance in the kids because of reductions in the amount of milk received from their mothers during lactation. In addition, the diet containing detoxified castor meals was not efficient in recovering from the loss of stored body reserves able to initiate the recovery of the cyclic activity of the goats.(AU)

Este estudo avaliou o efeito da torta de mamona desintoxicada na reprodução, no estresse metabólico, na produção de leite e no desenvolvimento de cabritos no periparto de cabras. Um grupo foi alimentado com torta de mamona (DCM, n=20), e o outro (WDCM, n=21) não recebeu tal suplemento , durante a gestação até o desmame, 60 dias pós-parto. Não foram observadas diferenças significativas no período de gestação, no número de cabritos, na taxa de partos múltiplos e na mortalidade entre os dois grupos. Em todos os animais, a concentração plasmática de progesterona ficou abaixo de 1ng/mL, confirmando a ausência de atividade lútea. A espessura da gordura subcutânea do esterno e da área de olho-de-lombo, a concentração de ureia e colesterol, a produção de leite e o ganho de peso dos cabritos foram menores no grupo DCM (P<0,05). Conclui-se que o uso de torta de mamona desintoxicada no periparto de cabra resultou em cabritos mais leves devido à redução na produção de leite das matrizes e as cabras não retornaram ao cio, pois não recuperaram a massa corporal.(AU)

Nutritional impact on gene expression and competence of oocytes used to support embryo development and livebirth by cloning procedures in goats.

Changes in the nutritional plan have been shown to affect oocyte quality, crucial to oocyte donors animals used in cloning. This study aimed to evaluate the impact of diets with increasing nutritional levels (maintenance diet=M; 1.3M; 1.6M; 1.9M) fed to goats for four weeks on follicular fluid composition, gene expression and oocyte competence used to cloning in goats. Donor females were superovulated for the retrieval of matured oocytes and physical measurements reported. After four weeks, groups receiving diets above maintenance increased thickness of subcutaneous adipose tissue and body weight, with higher values in 1.9M Group (P<0.05). Treatments did not affect follicular density, number of aspirated follicles, retrieved and matured oocytes. Animals from 1.3M group had lower (P<0.05) maturation rate (44.0%) and number of viable oocytes (65.3%) than M (68.8%) and 1.9M (76.0%). Follicular fluid glucose concentrations increased with nutritional levels (P=0.010), with a difference (P<0.05) between groups 1.9M (11.4±2.6mg/dL) and M (2.6±0.5mg/dL). The diet did not affect the expression of GDF9, BMP15, and BAX genes in oocytes, but BCL2 and apoptotic index were significantly higher (P<0.05) in the 1.3M and 1.6M groups than the other groups. Following the transfer of cloned embryos, one fetus was born live of a twin pregnancy in the 1.9M Group. The association between energy intake and oocyte quality suggests better nutritional use by oocytes when the maximum flow was used (1.9M), but the optimal feeding level in cloning still needs refinement.

Meat quality assessment from young goats fed for long periods with castor de-oiled cake.

Diet can influence both the qualitative and quantitative traits of ruminant meat. This study evaluated the effects of castor de-oiled cake on the meat of mixed-breed male goat kids. After 165days of diet treatment, no alterations (p>0.05) were observed in the in vivo performance, anatomic components, dissection and proximate composition of the Longissimus dorsi muscle, as well as in the color and pH of the carcasses. However, diet had an effect (p<0.05) on energy metabolites, fatty acid profile, and expression of certain proteins of the Longissimus dorsi muscle. To conclude, this study showed that the establishment of castor de-oiled cake diet for a long period to goats led to alterations in meat quality, without compromising its consumption qualities.

Growth, testis size, spermatogenesis, semen parameters and seminal plasma and sperm membrane protein profile during the reproductive development of male goats supplemented with de-oiled castor cake.

The present study was conducted to evaluate the effect of de-oiled castor cake on reproductive traits of crossbreed goats. Fourteen males were grouped into two lots (n = 7/group), as described: group without de-oiled castor cake (WCC) and group fed with de-oiled castor cake (CC). Goats received two diets containing a mixture of Bermudagrass hay and concentrates with the same energy (73% total digestive nutrients) and protein content (15% crude protein) during 150 days, corresponding to ages from 40 (puberty) to 60 weeks. Blood plasma concentrations of urea, albumin, lactate dehydrogenase, creatinine, alanine aminotransferase and testosterone were determined. We also evaluated scrotal circumference, sperm parameters, quantitative aspects of spermatogenesis and daily sperm production (DSP), as well as the proteome of seminal plasma and sperm membrane. Seminal fluid and sperm proteins were analyzed by 2D SDS-PAGE and mass spectrometry. After 150 days of castor cake feeding, animals had no changes in the biochemical composition of blood plasma, suggesting the absence of intoxication by ingestion of ricin. There were no alterations in dry mater intake, weight gain, testis size, peripheral concentrations of testosterone, sperm concentration, motility and morphology. Sertoli and germ cell populations in the testis and DSP were not affected either. However, there were significant variations in the expression of five seminal plasma proteins and four sperm membrane proteins. In conclusion, the replacement of soybean meal by castor cake (with ricin concentrations of 50mg/kg) did not interfere with the growth and core reproductive development of male goats. However, the diet with ricin altered the expression of certain seminal plasma and sperm membrane proteins, which play roles in sperm function and fertilization. Lower expression of these proteins may impair the ricin-fed animals to perform as high-fertility sires.

Expressão gênica de adipocinas em ovelhas alimentadas com resíduos da indústria do biodiesel da mamona / Adipokine gene expression in ewes fed with residues from the biodiesel castor industry

A expressão de RNAm para leptina, receptor de leptina (obRb), adiponectina, receptor de adiponectina (AdipoR1) e resistina foi avaliada por meio da técnica de PCR em tempo real, em tecidos ovariano, hipofisário, adiposo do omento e da região perirrenal, em ovelhas alimentadas sem farelo de mamona ou com farelo de mamona detoxificada durante 14 meses. O tipo de dieta não afetou os níveis de RNAm para leptina, obRb, adiponectina, AdipoR1 e resistina nos diferentes tecidos avaliados (P>0,05). Nos tecidos ovariano e hipofisário, não foi verificada a expressão da adiponecina e da resistina, respectivamente. Como consequência, pode-se concluir que o farelo de mamona detoxificada pode ser utilizado como fonte proteica na dieta de ovelhas, sem afetar a expressão do gene resistina e dos genes leptina e adiponectina, bem como de seus receptores...

The expression of leptin, leptin receptor (obRb), adiponectin, adiponectin receptor (AdipoR1) and resistin was assessed by real-time PCR technique in ovarian, pituitary, and the omental adipose perirenal tissue in sheep feed without castor meal or with detoxified castor meal. The type of diet did not affect mRNA levels for leptin, obRb, adiponectin, resistin AdipoR1 evaluated in different tissues (P>0.05). However, in pituitary and ovarian tissues there was no expression of resistin and adiponectin, respectively. The detoxified castor meal can be used in sheep diets as alternative food protein without affecting the expression of leptin and adponectin as well as their receptors and resistin...

Comparative expression profiles of genes related to oocyte development in goats after long-term feeding with biodiesel castor industry residues.

The aim of this study was to determine whether the consumption of detoxified castor meal (DCM) by goats over a long period of time affects mRNA levels in oocytes, and in mural granulosa and cumulus cells. A total of 41 adult does were supplemented (DCM group, n=21) or not (control group, n=20) with detoxified castor meal (DCM) for a period of 500 days. Then, 13 and 12 does were randomly selected for slaughter from the DCM and control treatments groups, respectively, for the determination of the number of visible ovarian follicles, retrieved cumulus-oocyte complexes (COCs), and viable and non-viable oocytes. The relative expression levels for distinct genes were determined by quantitative PCR in viable immature oocytes prior to in vitro maturation (IVM), in oocytes attaining or not the metaphase stage after IVM, as well as in granulosa cells obtained upon oocyte collection, and in cumulus cells obtained after IVM. The number of follicles ≥4 mm did not differ between treatments (overall mean 23.3 ± 2.0) and no significant differences were observed in the recovery of viable, non-viable, or total mean numbers of oocytes (control group: 44.7 ± 4.6, DCM group: 54.9 ± 5.9, respectively) between control and DCM fed goats. The maturation rate was significantly higher for control than DCM oocytes (58.0% vs. 45.3%; P<0.05). The mRNA levels in immature COC for controls were significantly higher for GLUT1 and lower for HSP70 (P<0.05) than for DCM. Following maturation, MII oocytes from both treatments had mRNA levels that were significantly higher for GDF9 and lower for BMP15 than for NC oocytes (P<0.05). In cumulus cells, the mRNA levels were significantly higher for LHR, FSHR, LeptinR, and IGF1, and lower for MnSOD in the control group compared with the DCM group (P<0.05). In conclusion, the inclusion of DCM in goat feed for long periods of time changed gene expression in immature oocytes and in cumulus cells. This was reflected by a decrease in the in vitro oocyte maturation rate.

Goat oocyte quality and competence to undergo IVM and embryo development after parthenogenetic activation from goats fed with different levels of cashew nut bran as source of dietary lipids.

Lipid-rich and energy-dense diets can have significant effects on the reproductive physiology, including the ovarian function and fertility. The aim of this study was to assess the effect of cashew nut bran supplementation as a lipid source on follicle development, plasma and intrafollicular concentrations of cholesterol, and developmental competence of in vitro-matured goat oocytes. The inclusion of cashew nut bran as 24% of the goats' diet for 28 days increased the percentage and number of degenerated oocytes compared with the control (P < 0.05), and also the plasma cholesterol levels and the proportion of grade IV oocytes compared with all other treatments (P < 0.05). Moreover, a significant reduction was observed in the proportion of viable oocytes compared with the control and in the percentage of grade II oocytes compared with all other treatments (P < 0.05). Oocyte maturation, cleavage, and blastocyst rates after parthenogenetic activation of viable oocytes were not affected by the type of diet. In conclusion, the inclusion of cashew nut bran as 24% of the diet of adult goats for 28 days changed plasma cholesterol levels and reduced the proportion of viable immature oocytes; however, the 12% and 24% diet supplementations with cashew nut bran did not interfere with competence of resulting viable oocytes to reach the metaphase II stage after IVM, and to develop after parthenogenetic activation.

Respostas reprodutivas e metabólicas de ovelhas alimentadas com bagaço de caju desidratado, durante o pós-parto / Reproductive and metabolic responses of ewes fed dehydrated cashew apple bagasse during the postpartum period

Avaliou-se o efeito da adição de bagaço de caju desidratado (BCD), durante o pós-parto, em 41 ovelhas, alojadas com suas crias em baias, onde recebiam, à vontade, 75 por cento de capim-elefante + 25 por cento de concentrado (DI; n=17), ou 50 por cento de BCD + 25 por cento de capim-elefante + 25 por cento de concentrado (DII; n=24). Cinquenta dias pós-parto, o estro foi sincronizado, e as ovelhas submetidas à monta natural. O grupo DI perdeu mais peso (P<0,05), e o consumo de proteína bruta e de fibra em detergente neutro foi maior nesse grupo (P<0,001). A inclusão de BCD na dieta II induziu ao aumento do consumo de matéria seca, extrato etéreo e fibra em detergente ácido (P<0,001) e redução significativa das concentrações de colesterol, lipídios totais, albumina e proteína total (P<0,001). Não houve diferença entre os grupos (P>0,05) no tempo de retorno do primeiro corpo lúteo funcional, na resposta à sincronização do estro e nas taxas de gestação e prolificidade. A inclusão de 50 por cento de BCD amenizou as perdas de peso, foi bem consumida e não influenciou nas respostas reprodutivas após a sincronização do estro.

The effect of the addition of dehydrated cashew apple bagasse (DCB) to the diet on ewe postpartum response was evaluated on 41 ewes, housed with their kids in pens, where they received two diets containing 75 percent of Elephant Grass plus 25 percent of concentrate (Diet I; n=17), or 50 percent of DCB plus 25 percent of Elephant Grass plus 25 percent of concentrate (Diet II; n=24). On the 50th day postpartum, estrus was synchronized and ewes mated. Diet Igroup exhibited a greater loss of live weight (P<0.05) and higher intakes of crude protein and neutral detergent fiber (P<0.001). By contrast, animals from diet II showed a significantly increase in dry matter, ether extract, and acid detergent fiber intakes (P<0.001), and lower plasmatic concentrations of cholesterol, total lipids, albumin, and total protein (P<0.001). No differences were found between groups (P>0.05) for the presence of first functionally CL, estrus synchronization response, and gestation or prolificity rates. Thus, the addition of DCB to the diet was well accepted, induced a reduction of weight loss, and did not affect the reproductive response of ewes.

Embryo production in superovulated goats treated with insulin before or after mating or by continuous propylene glycol supplementation.

Seventeen adult and cyclic Moxoto goats were synchronized using 60 mg MPA vaginal sponge for 11 days and 50 mug cloprostenol, 48 h before sponge removal, and superovulated with 120 mg pFSH i.m. in decreasing doses at 12 h intervals for three consecutive days. In seven goats, 0.2 IU/kg BW/day of long acting insulin was subcutaneously injected at same time as pFSH, and in the other five goats, the same dose of insulin was injected for three consecutive days starting 24 h after mating. Finally, five goats were supplemented with an oral dose of 80 ml/goat/day of propylene glycol continuously during the experiment. The animals were flushed at 7 days after mating and the embryos were classified based on International Embryo Transfer Society criteria. Blood samples were collected every 3 days for insulin assay. Administration of insulin raised the insulin levels of the goats (p < 0.05), whereas in the group treated with propylene glycol, insulin rate was different only between FSH treatment and after mating (p < 0.05). Similar rates of recovery for total (80.05 +/- 9.78%) or transferable structures (61.03 +/- 15.13%) were obtained. Treatment was not influenced (p > 0.05) by responsiveness to superovulation, which averaged 64%. By contrast, insulin treatments were shown to increase the number of embryos considered excellent with respect to goats supplemented with propylene glycol (p < 0.05). When insulin was given before mating, a strong relationship (r = 0. 90) (p < 0.05) between number of transferable embryo and ovulations was observed in the animals. In conclusion, superovulated goats treated with low doses of exogenous insulin resulted in an enhancement in embryo quality, which was related to changes in circulating insulin concentrations.

Cryopreservation of sheep primordial follicles.

The aim of this study was to evaluate the efficiency of 1 M dimethylsulphoxide (DMSO), ethylene glycol (EG), propylene glycol (PROH) and glycerol (GLY) to cryopreserve primordial follicles. The first evaluation was performed soon after cryopreservation and the second evaluation after 4 days of in vitro culture, using the cryoprotectants that allowed the higher results (higher follicular survival rate) after cryopreservation. The results after follicular isolation (control) and cryopreservation using 1 M DMSO, EG, PROH and GLY showed that the mean number (+/- SEM) of live follicles per millilitre was 3204 (100%) +/- 319.27, 2798 (87%) +/- 239.14, 2492 (78%) +/- 345.8, 448 (14%) +/- 46.3 and 208 (7%) +/- 75.26, respectively. Higher follicular survival was reported when DMSO and EG were used. Control follicles and follicles cryopreserved with these two cryoprotectants were cultured and the percentage of follicular survival was 55% (control), 42% (EG) and 34% (DMSO). Similar results were found between control and follicles cryopreserved with EG. In conclusion, 1 M EG is the most effective cryoprotectant to preserve primordial follicles isolated from ovaries of sheep.

Effect of age of donor on embryo production in Morada Nova (white variety) ewes participating in a conservation programme in Brazil.

In order to evaluate embryo production in Morada Nova (white variety) ewes superovulated with porcine follicle-stimulating hormone, 20 cycling ewes were used as embryo donors and allocated into two groups according to age: group 1 (ewes aged 1-2 years; n = 9) or group 2 (ewes aged 3-4 years; n = 11). Embryo recovery was performed by laparotomy 5-6 days after oestrus. The evaluation of embryos was made under stereomicroscope according to International Embryo Transfer Society rules. The overall recovery rate was 64.6% (5.0 +/- 0.7 structures per ewe) and 86.3% of the recovered structures were fertilized. Group 1 was superior (p < 0.05) to group 2 according to recovered (6.6 +/- 0.9 vs 3.6 +/- 0.8) and fertilized structures (5.6 +/- 1.1 vs. 3.5 +/- 0.7) per ewe. In conclusion, the ovarian response and the embryo production in Morada Nova (white variety) sheep subjected to a standard superovulation treatment were considered satisfactory. In addition, the use of multiple ovulation and embryo transfer in younger ewes ( < or = 2 years old) of this sheep breed appears to be an efficient tool to accelerate the preservation of the Morada Nova (white variety) breed, since younger ewes are as responsive as older ones.

Effect of nutrition on plasma progesterone levels, metabolic parameters and small follicles development in unstimulated goats reared under constant photoperiod regimen.

Sixteen local adult goats were submitted for 9 weeks to 2.09 (high group) and 0.54 (low group) x dietary maintenance respectively. During the experimental period, goats were weighed, oestrus was detected and plasma insulin, urea, non-esterified fatty acids and progesterone concentrations were assessed. At the end of the experiment, ovarian small follicles population was studied by histological analysis. Final weight loss in low group was 18.37 +/- 2.02%, whereas weight gain of high group was 13.84 +/- 2.70%. Insulin and urea were lower in low group, while non-esterified fatty acids were significantly higher. A lower number of fasted goats was in oestrus or ovulated and an extended length of oestrus (p < 0.05) and a higher frequency of short or long cycles (p < 0.05) were also observed. Fed animals showed heavier ovaries (p < 0.01) and a lower number of primordial follicles (p < 0.05). In restricted goats a significant qualitative alteration of follicle classes involved in the initiation process of primordial pool was found. In this phase, granulosa thickness and oocyte size were the most affected (p < 0.01). However in small follicles beyond the primary stage no differences were found between the groups in either number or qualitative characteristics (p > 0.05). Collectively, these results indicate that opposite dietary intakes for a medium period induce a composite reproductive response in goats and can regulate the early onset of follicle growth.

Responsiveness to progestagen-eCG-cloprostenol treatment in goat food restricted for long period and refed.

For 6 months, 10 adult Saanen crossbred goats were fed undernutrition diet (70% maintenance), and finally five goats were refed for 6 weeks with 150% maintenance. In all animals oestrus was synchronized using 45 mg FGA vaginal sponge for 11 days, 300 IU eCG and 50 microg cloprostenol 48 h prior to sponge removal. From oestrus onset, during a 24-h period, blood samples were collected for oestradiol and NEFA assay. Ovulation was verified by laparoscopy 3 days after sponge removal. Body mass loss was 18.62 +/- 3.03% of initial weight and in refed goats body weight recovery was 90.63 +/- 3.56%. NEFA level was higher in restricted goats (p < 0.05). Fifty per cent of underfed goats (2/4) and all refed goats (4/4) exhibited oestrus and ovulation. Significant relationship (p < 0.05) was found between weight loss and the interval sponge removal-oestrus onset (r = 0.91) or ovulation rate (r = 0.70). Only in the refed group was the ovulation rate related to the oestradiol amount (r = 0.99) (p < 0.05). Collectively results showed that a short period of improved feeding re-established the responsiveness of oestrus synchronization in chronically fasted goats.

Leptin stimulates the reproductive male axis in rats during sexual maturation by acting on hypothalamic excitatory amino acids.

The purpose of the present study was to determine the effect of treatment with leptin on gonadotrophin secretion and hypothalamic GnRH, excitatory and inhibitory amino acids release, in prepubertal (15 days old) and peripubertal (30 days old) male rats. Rats of both ages received a single (ip) injection of 30 microg/kg leptin 60 minutes previous to sacrifice. Serum LH was determined, and the hypothalamus dissected and incubated in Earle's medium. GnRH and amino acids release were determined in the media. LH and GnRH were measured by RIA. Amino acids were assessed by HPLC-UV detection. In the two prepubertal stages, (prepubertal and peripubertal, 15 and 30 days of age respectively) leptin increased plasmatic LH levels (p < 0.01) and hypothalamic GnRH release (p < 0.01). Glutamate (GLU) release showed an increment in leptin-treated rats (p < 0.01) at both ages, while only the 30 days old rats showed an increment of the aspartate (ASP) release. GABA secretion was not modified by leptin treatment. In conclusion, the results demonstrated that leptin stimulates the LH-GnRH axis during sexual development in male rats, increasing the secretion of both hormones. The hypothalamic excitatory amino acid neurotransmitter system appears to be involved in this change.

Hormonal treatments for the synchronisation of oestrus in dairy goats raised in the tropics.

In tropical areas, local goats are often reported as being able to reproduce throughout the year, whereas an influence of season is found to be a factor when importing different dairy breeds. In these areas, oestrus synchronisation in goats is of interest for both technical (synchronisation of kidding, adjustment to forage availability or to continuous milk supply) and genetic reasons (dissemination of improved genotypes by AI). The use of a progestagen vaginal sponge combined with equine chorionic gonadotrophin (eCG)-cloprostenol injections remains an efficient tool to achieve synchronisation in temperate and tropical zones. However, the oestrus synchronisation treatments currently used for goats in tropical regions were originally developed for goats bred in temperate regions. For this reason, several alternative possibilities for improving the efficiency of the hormonal treatment are evaluated. Oestrus synchronisation with luteolytic agents is efficient (resulting in more than 70% of goats in oestrus) and it takes into account female cyclicity. In developing regions of the tropics, the use of buck teasing appears to be a promising approach to control oestrus and ovulation. The use of this technique provides 60% of females in oestrus within 5 days of introducing the bucks. Considering the availability of nutrients as the ultimate regulator of reproduction in the tropics, the control of nutritional condition is essential before the use of hormonal treatments for oestrus synchronisation in goats bred in these regions takes place.

Pseudopregnancy in Saanen goats (Capra hircus) raised in Northeast Brazil.

The prevalence of pseudopregnancy over 44 months was investigated in 23 Saanen goats raised in Northeast Brazil during continuous oestrous cycling (cyclic group) or after synchronization of oestrus (synchronized group). The goats were monitored by ultrasonography and their plasma progesterone profile. The overall prevalence of pseudopregnancy was 30.4% (7/23). In the cyclic group, 28.6% (4/14) of goats showed pseudopregnancy, while in the synchronized group the prevalence was 33.3% (3/9). There was no significant difference between the groups (p>0.05). The mean (+/- SD) length of pseudopregnancy, as shown by the progesterone profile, was 121.6 +/- 33.5 days, ranging from 70 to 155 days. The study defined the prevalence of pseudopregnancy in Saanen goats raised in Northeast Brazil for the first time. This finding identified a major problem for this breed, as without treatment such animals remain unproductive until the spontaneous resolution of the condition. More research seems desirable to ascertain the prevalence of this condition in other breeds in this region of Brazil.

Effect of leptin on hypothalamic release of GnRH and neurotransmitter amino acids during sexual maturation in female rats.

The purpose of the present study was to analyse the effect of leptin treatment on the hypothalamic release of GnRH, GABA, and the excitatory amino acids (EAA), aspartate (ASP) and glutamate (GLU) involved in NMDA neurotransmission in prepubertal (15 day old) and peripubertal (30 day old) female rats. The animals were treated with a single dose of leptin (30 microg/kg i.p.) and sacrificed 60 min later. Hypothalamic samples were incubated in Earle's medium; GnRH was determined by RIA and GLU, ASP and GABA by HPLC by UV detection. The hypothalamic release of GnRH was increased by leptin at both ages, the release being significantly higher in peripubertal than in prepubertal rats. The levels of hypothalamic GABA release were different in the two groups; whereas in prepubertal rats the hypothalamic release of GABA increased with leptin administration, the neurotransmitter release decreased in the peripubertal group. On the other hand, the release of ASP was modified only in the peripubertal group, where leptin significantly increased its hypothalamic release. No modifications in leptin-induced hypothalamic release of GLU were observed at the two ages studied. In conclusion, the results showed that leptin increased GnRH release by the hypothalamus of prepubertal and peripubertal rats. In peripubertal rats this increase was accompanied by a significant decrease in the hypothalamic release of GABA as well as an enhanced release of ASP. These results and previous reports suggest that at this stage of sexual maturation, leptin exerts an stimulatory effect on GnRH by inducing release of excitatory amino acids (ASP) and reducing release of inhibitory amino acids (GABA) involved in GnRH control. In prepubertal rats the stimulating effect of the adipocyte hormone on GnRH appears to be related to its stimulative action on GABA which at this age increases GnRH release.