Animal welfare and effects of per-female stress on male and cattle reproduction-A review.

Thermal stress causes severe effects on the wellbeing and reproduction of cattle, including changes in oogenesis and spermatogenesis, generating great concerns, which last for decades. In cattle, the occurrence of thermal stress is associated with a reduction in the production of spermatozoids and ovarian follicles, in addition to the increase of major and minor defects in gametes or in their intermediate stages. In bovine females able to reproduce, a reduction in the rate of estrus manifestation and an increase in embryonic mortality has been observed. Therefore, keeping animals on good welfare conditions, with water supply and in shaded areas can favor the improvement of different reproductive parameters. For all this, the present study aimed to gather, synthesize and argue recent studies related to animal welfare, focusing on the effects of thermal stress on the reproduction of cattle, aiming to support possible strategies to mitigate the harmful effects of thermal stress in this species.

Synchronization of follicular wave emergence does not improve embryonic yield in superovulated ewes.

The present study aimed to investigate the effects of a combination of progesterone with different doses of E-17ß on following end points: (1) ovarian follicular dynamics and emergence of a new follicular wave, and (2) superovulatory response and embryo yield. In Experiment 1, 28 ewes were randomly divided into four groups (n = 7) to receive either 2.0 mg, 1.0 mg, 0.5 mg or none E-17ß one day after insertion of a progesterone device. The different doses of estradiol similarly delayed the moment of follicular emergence (overall mean = 3.1 ± 1.0 days vs. control group = 0.86 ± 1.0 days; P < 0.01), but the emergence of the new wave showed greater synchronization with the 0.5 mg dosage of E-17ß. In Experiment 2, sixty-two donor ewes received an internal progesterone release device (day -1) for 7 d and 1 d after the insertion of this device (day 0) were allocated randomly to receive 0.5 mg of E-17ß or only the vehicle (control group). Superstimulation was initiated on day 3 with the administration of 133 mg of pFSH in eight decreasing doses. Contrary to expectations, the protocol with the administration of 0.5 mg E-17ß did not improve the percentage of donors with > 2 CL, the number of CL and the production of embryos (P > 0.05). It was concluded that the combination of progesterone and 0.5 mg E-17ß was more efficient in synchronizing the emergence of the new follicular wave, however this approach seems to be unnecessary in ewe's superovulation programs.

Culture of goat preantral follicles in situ associated with mesenchymal stem cell from bone marrow.

This study aims to develop an in vitro co-culture system of in situ goat preantral follicles with bone marrow-derived mesenchymal stem cells (BM-MSC), evaluating the influence of these cells on follicular growth, rate of activation and morphologically normal follicles. Fragments of ovarian cortex were cultured for 1 or 7 days in the presence of BM-MSC (BM-MSC+) and absence of BM-MSC (BM-MSC-). Histological sections of the fragments were analysed and data were obtained regarding morphological classification, survival rate of morphologically normal follicles and rate of follicular activation. Culture medium on days 1 and 7 was also sampled for nitrite concentration and reduced glutathione activity. There was a reduction (P < 0.05) in the percentage of morphologically normal follicles in the BM-MSC+ compared with the fresh control only on the seventh day of culture. When comparing treatments, on the seventh day of culture, a higher rate of morphologically normal preantral follicles was observed in BM-MSC+ (P < 0.05). In both treatments, primordial and developing follicle rates were similar to the fresh control (P > 0.05). When comparing treatments with each other, as well as with the fresh control, no differences were observed in follicular diameter (P > 0.05) or nitrite concentration (P > 0.05). The concentration of reduced glutathione was lower on the seventh day of co-culture in both treatments (P < 0.05). In conclusion, co-culture had no influence on follicular or oocyte development. However, it was critical to maintain the survival of preantral follicles during 7 days of culture.

Effect of oestrous resynchronization on the reproductive efficiency of zebu cows.

The aim of this study was to develop a resynchronization strategy before the return of oestrus in cows diagnosed as not pregnant after fixed-time artificial insemination (TAI). A total of 839 cows, approximately 45 days post-partum, were synchronized using TAI. On day 0, intravaginal progesterone-releasing devices were inserted and 2 mg of oestradiol benzoate was administered. Eight days later (D8), the progesterone-releasing devices were removed and oestradiol cypionate (0.5 mg, eCG [300 IU]) and prostaglandin (7.5 mg) were administered. All cows were inseminated between 48 and 56 hr after device removal (D10). Thirty days after TAI, cows that were not diagnosed as pregnant by ultrasound were immediately resynchronized and again inseminated at a fixed time. The hormonal protocol used in the first and second rounds of TAI was the same. The pregnancy rate after the first TAI was 52%, and after the second TAI, it was 49%. The increase in the total pregnancy rate (synchronization + second oestrous synchronization) compared to a single synchronization was 23.5%. In conclusion, resynchronization of oestrus and ovulation in zebu cows that had previously undergone TAI protocols is effective in increasing the reproductive efficiency.

Milk production in Saanen goats treated with repeated low doses of intermediate-release insulin during early lactation / Produção de leite em cabras Saanen tratadas com repetidas doses baixas de insulina de liberação intermediária durante a lactação inicial

ABSTRACT: The effect of insulin administration on the productive responses of Saanen goats during early lactation was investigated. Ten of 20 adult females were subjected to subcutaneous administration of intermediate-acting insulin (0.14UI/kg body weight) at 2, 9, and 14 days postpartum. Milk yield was measured twice daily for 13 weeks and milk samples were collected to measure protein and fat contents. Plasma levels of progesterone, insulin, non-esterifies fatty acids, glucose and other metabolites were measured. Results showed a significantly increased effect of insulin treatment on the content of milk fat and protein; moreover, milk production in the first and second postpartum weeks were higher than control group. The peak of lactation in the insulin group was achieved one week earlier in comparison to the control group. In addition, the milk production rate showed lower persistency (milk yield 13 week/milk yield at peak) in the same group. During the first four weeks of postpartum, treated animals showed greater weight loss and higher non-esterified fatty acid concentration, whereas no effect was observed on the concentration of progesterone and other metabolites. The above results indicated that repeated administration of insulin in dairy goats during early lactation increase yield and qualitative components of milk, but has substantial consequences on animal productive rate and metabolic response.

RESUMO: O objetivo do estudo foi avaliar o efeito da administração de insulina sobre a resposta produtiva de cabras Saanen durante a lactação inicial. Dez de vinte fêmeas adultas foram sujeitas à administração subcutânea de repetidas e baixas doses de insulina de liberação intermediária aos 2, 9 e 14 dias pós-parto. A produção de leite foi mensurada duas vezes ao dia, por 13 semanas, e amostras de leite foram coletadas para mensurar teores de proteína e gordura. Os níveis plasmáticos de progesterona, insulina, ácidos graxos não-esterificados (AGNE), glicose e outros metabólitos foram mensurados. Os resultados mostraram um efeito significativamente maior nos animais tratados com insulina sobre o teor de gordura e proteína no leite. Além disso, a produção de leite na primeira e segunda semana pós-parto foi maior no grupo tratado do que no grupo controle. O pico de lactação no grupo insulina foi alcançado uma semana antes em comparação ao grupo controle. Além disso, a taxa de produção de leite nos animais tratados mostrou uma menor persistência de produção de leite durante o período analisado. Durante as primeiras quatro semanas pós-parto, os animais tratados com insulina mostraram maior perda de peso e maior concentração de AGNE, enquanto não se observou nenhum efeito sobre a concentração de progesterona ou outros metabólitos. Os resultados acima indicam que repetidas doses de insulina em cabras leiteiras durante a lactação inicial aumenta o rendimento de produção e concentração de componentes qualitativos do leite, mas apresenta consequências consideráveis sobre taxa de produção animal e resposta metabólica.

Activin-A promotes the development of goat isolated secondary follicles in vitro.

The role of activin-A in follicular development and on the mRNA expression levels of different genes in goat secondary follicles was evaluated. Goat secondary follicles (≥ 150 µm) were cultured for 18 days under control conditions or with the addition of either 50 or 100 ng/ml activin-A (Experiment 1). The mRNA levels for the genes that code for activin-A, ActR-IA, ActR-IB, ActR-IIA, ActR-IIB, follicle stimulating hormone receptor (FSH-R) and P450 aromatase were measured in each condition (Experiment 2). We observed that after 6 days of culture, the antrum formation rate was higher in cultures with added activin-A than in the cultured control (P < 0.05). The addition of 50 ng/ml activin-A increased the follicular growth rate in the final third of the culture (days 12-18), resulting in a higher percentage of meiosis resumption (P < 0.05). On day 6, the addition of activin-A (50 ng/ml) increased the levels of ActR-IA mRNA compared with the cultured control (P < 0.05). After 18 days, the addition of 50 ng/ml activin-A significantly increased the levels of its own mRNA compared with the non-cultured control. Moreover, this treatment reduced the mRNA levels of P450 aromatase in comparison with the cultured control (P < 0.05). Higher levels of P450 aromatase mRNA were found for both activin-A treatments compared with the non-cultured control (P < 0.05). No difference in estradiol levels was detected among any of the tested treatments. In conclusion, the addition of activin-A to culture medium stimulated early antrum formation as well as an increase in the daily follicular growth rate and the percentage of meiosis resumption.

Frozen and fresh ovarian tissue require different culture media to promote in vitro development of bovine preantral follicles.

The aim of this study was to evaluate the efficiency of different media in the in vitro culture of bovine preantral follicles that were used either fresh or following slow freezing treatment. Frozen and fresh noncultured or cultured ovarian fragments were processed for histological, viability, and cell proliferation analyses. For cryopreservation, a solution containing 1.5 M ethylene glycol was frozen in a programmable biological freezer. After thawing, a portion of the samples was destined for frozen controls. The remainder were cultured in vitro for 5 days in three media: α-MEM, McCoy, or M199. Samples from these culture media were collected on days 1 and 5 for quantification of reactive oxygen species (ROS) and for hormonal assays. In fresh-cultured tissues, the percentage of morphologically normal follicles was significantly higher when cultured in M199 compared to that in the other media. In frozen-cultured tissues, McCoy medium was significantly superior to the other media, and was the only treatment that helped in maintaining the viability similar to fresh and frozen controls. Upon quantification of the nucleolus organizer region, we observed greater proliferation of granulosa cells in the frozen-cultured tissues with McCoy medium, and lesser proliferation in fresh-cultured tissues only with α-MEM. In frozen-cultured tissues, ROS levels were highest at day 1 and progressively reduced during culture, independent of the media used. In conclusion, under the conditions used in this study, the M199 and McCoy media are recommended for the culture of follicles derived from fresh and frozen ovarian tissues, respectively.

Effect of medium composition on the in vitro culture of bovine pre-antral follicles: morphology and viability do not guarantee functionality.

Summary This study investigated the effect of three different culture media (α minimum essential medium (α-MEM), McCoy or TCM199 during the in vitro culture (IVC) of bovine isolated pre-antral follicles. Pre-antral follicles greater than 150 µm in size were isolated and cultured for 0 (control), 8 or 16 days in one of the abovementioned culture media. Follicles were evaluated for survival, growth and antrum formation at days 8 and 16. The results showed that TCM199 was the most suitable medium to preserve follicular viability and ultrastructure, resulting in the highest rates of antrum formation. In conclusion, TCM199 promotes the in vitro development of isolated pre-antral follicles without hampering follicular functionality by sustaining in vitro growth and antrum formation.

Freezing solution containing dimethylsulfoxide and fetal calf serum maintains survival and ultrastructure of goat preantral follicles after cryopreservation and in vitro culture of ovarian tissue.

Goat ovarian cortex fragments were subjected to slow freezing in the presence of various solutions containing intracellular cryoprotectants, including 1.0 M ethylene glycol (EG), propanediol (PROH), or dimethyl sulfoxide (DMSO), with or without sucrose and/or fetal calf serum (FCS). Histological examination revealed that only the DMSO-containing solutions were able to maintain a follicular ultrastructure similar to the morphology observed in the fresh control. Therefore, fragments previously cryopreserved in DMSO solutions (with and without sucrose and/or FCS) were cultured in vitro for 48 h and then subjected to viability, histological, and ultrastructural analysis. No significant differences were observed among the percentages of morphologically normal follicles in cryopreserved ovarian tissue before in vitro culture (DMSO: 62.5%; DMSO + sucrose: 68.3%; DMSO + FCS: 60.0%; DMSO + sucrose + FCS: 60.0%) and after culture (DMSO: 60.8%; DMSO + sucrose: 64.2%; DMSO + FCS: 70.8%; DMSO + sucrose + FCS: 55.0%). Following in vitro culture, the viability analysis showed that only the freezing solution containing DMSO and FCS (75.6%) maintained a percentage of viable follicles similar to that observed after culture without cryopreservation (89.3%). As determined by ultrastructural analysis, morphologically normal preantral follicles were detected in the fresh control and in fragments cultured before and after cryopreservation with DMSO and FCS. Thus, a freezing solution containing DMSO and FCS, under the experimental conditions tested here, guaranteed the maintenance of viability and follicular ultrastructure after short-term in vitro culture.