Mixed-Effects Modelling of the Risk Factors Associated with Multiple Pregnancies in Thoroughbred Mares.

Multiple pregnancies (MPs) are commonly diagnosed during breeding management of mares. Whilst some studies have reported on factors associated with the risk of MPs, few have utilised multivariable data analysis to control for confounding variables. A prospective cohort study of Thoroughbred broodmares was conducted with information collected on 27 factors. Mixed-effects logistic regression was used to determine risk factors for MPs. Mare, stallion, stud, and veterinarian were evaluated as random effects. The prevalence of MPs in 1754 mares and 2245 pregnancies was 16.06% (95% confidence interval [CI] = 14.54, 17.58). Multiple ovulations (OR = 15.57, 95% CI = 11.88, 20.53) and treatment with cloprostenol (OR = 1.35, 95% CI = 1.015, 1.80) were associated with increased odds of MPs following multivariable analysis. Mares that foaled at the start of the breeding season (OR = 0.66, 95% CI = 0.47, 0.94), conceived at the second or more oestrus cycles (OR = 0.60, 95% CI= 0.43, 0.84), or identified with a uterine cyst (OR = 0.63, 95% CI = 0.40, 0.97) were at reduced odds of conceiving MPs. Mare, stallion, stud, and veterinarian were not associated with MPs. These findings provide possible explanations as to why the prevalence of MPs but not MOs have increased over the last decade.

Biostimulation with the ram effect increases the follicle recruitment, ovulatory diameter, and embryo viability rate in superovulated ewes.

The aim of this study was to compare the preovulatory follicular development and superovulatory outcomes in superovulated ewes which were either stimulated or not stimulated by placement with rams. The treatment regimen to super-stimulate ovarian follicular development was imposed to 28 ewes on "Day 0", from which 14 were stimulated with active rams for 48 h, starting at the time of the fifth FSH dose, with the ram being removed from the pen with the ewes and replaced which other ram every 12 h, using four different rams (group GRE). The other 14 ewes remained isolated from rams throughout the protocol (group GCON). All ewes were administered 133 mg of FSH, into six doses in decreasing quantities, every 12 h. The follicular development and number of ovulations were determined using ultrasonography. Biostimulation resulted in an increased number of large follicles, follicle diameter, and embryo viability rate (viable embryos/recovered structures∗100) was greater in ewes of the GRE than GCON group. The number of corpora lutea, follicular cysts, recovered structures, viable embryos, and degenerated and unfertilized structures was similar in ewes of the GRE and GCON group. Structures were recovered from more GRE than GCON ewes. In conclusion, biostimulation with rams during the last phase of the treatment regimen to induce superovulation enhanced the follicular growth and increased the embryo viability rate in ewes.

Progestogen supplementation during superovulation leads to higher embryo viability and TGFB1 gene expression in sheep.

This study aimed to compare the effect of the administration of either medroxyprogesterone acetate (MPA) or progesterone (P4) in superovulation (SOV) treatments applied during the first follicular wave on follicular development, embryo yield, and the expression of genes related to pluripotency maintenance, differentiation of the trophectoderm, cell growth and differentiation, apoptosis and energy metabolism in sheep embryos. The estrous cycle of 36 multiparous ewes was synchronized with a short protocol, and the animals were randomly allocated to three groups. At the beginning of SOV, 12 ewes per treatment received an intravaginal sponge impregnated with 60 mg of MPA (TMPA), or an intravaginal device containing 0.33 g of P4 (TP4), or received no progestogen treatment (CON). The device was kept until the fifth dose of FSH. Ewes were mated with five fertile rams. Gene expression was performed by RT-qPCR using grade I and II blastocysts. The numbers of corpora lutea, total structures and viable embryos recovered per ewe were similar (P > 0.05) among groups. However, the viability rate was higher in TP4 (71.9 ± 16.3%) compared to CON (24.4 ± 16.8%; P = 0.01) and similar to TMPA (49.9 ± 16.3%; P = 0.2). Similarly, when compared with CON, treatment with P4 or MPA positively regulated the TGFB1 transcript involved in cell proliferation and differentiation (P = 0.01 and P = 0.03, respectively). In conclusion, supplementation with P4 during the first follicular wave of the estrous cycle improves embryo viability and alters the expression of the TGFB1 gene.

Ovarian response to prostaglandin F2α in lactating dairy cows: A clinical update.

Prostaglandin F2α (PGF2α) and its analogs are used to induce luteolysis in estrus synchronization programs to terminate unwanted pregnancies or to promote ovulation in certain cow subpopulations. In the past few decades, the luteolytic dose of PGF2α has remained unchanged. This review explores the clinical implications of increasing the standard dose for these applications in high-producing dairy cows. Ultrasonography may assist in selecting the most appropriate PGF2α dose and improve the results. A reference has been used for PGF2α for promoting ovulation in herds showing poor reproductive performance.

Equine chorionic gonadotropin drives the transcriptional profile of immature cumulus-oocyte complexes and in vitro-produced blastocysts of superstimulated Nelore cows.

Studies have shown that the use of equine chorionic gonadotropin (eCG), which binds both follicle stimulating hormone (FSH) and luteinizing hormone (LH) receptors, could modify the female reproductive tract. We, thus, aimed to quantify the messenger RNA (mRNA) abundance of genes related to cumulus-oocyte complexes (COCs) and embryo quality in Nelore cows (Bos taurus indicus) submitted to ovarian superstimulation using only FSH (FSH group; n = 10) or replacement of the last two doses of FSH by eCG (FSH/eCG group; n = 10). All animals were slaughtered and the ovarian antral follicles from both groups (10-14 mm in diameter) were aspirated for cumulus, oocyte and in vitro embryo production gene expression analysis. The relative mRNA abundance of 96 genes related to COCs development and embryo quality was measured by RT-qPCR. We found that oocytes are more affected by eCG use and that 35 genes involved in lipid metabolism, oxidative stress, transcriptional control, and cellular development were upregulated in the FSH/eCG group. In blastocysts, lipid metabolism seems to be the main pathway regulated by eCG use. We suggest that these multiple effects could be due to the ability of eCG to bind LHR and FSHR, which could activate multiple signal transduction pathways in the superstimulated ovary, further impacting the transcriptional profile of COCs and blastocysts.

Effects of reducing dietary starch content by replacing barley grain with wheat dried distillers grains plus solubles in dairy cow rations on ovarian function.

Our objective was to evaluate the effects of dietary starch content, altered by partial substitution of dietary grain with wheat dried distillers grain with solubles (DDGS), on the interval from calving to first ovulation, concentrations of hormones and metabolites in plasma and follicular fluid, and granulosa cell gene expression in preovulatory follicles. Sixty lactating dairy cows were assigned to 1 of 2 diets from calving until 84d postpartum. Diets were formulated to contain either 17.3% rolled barley grain (29.2% starch) or 17.2% wheat DDGS (19.1% starch), with 43.0% barley silage and 21.6% rolled corn grain as the other major ingredients (dry matter basis). Transrectal ultrasonography was performed twice weekly to monitor ovarian dynamics from 7 ± 2d postpartum until ovulation or until 56d in milk, whichever occurred earlier. Plasma concentrations of insulin and insulin-like growth factor-1 (IGF-1) were determined in all 60 cows, and that of glucose, fatty acids, and urea in a subset of 24 cows, representing those in which the first ovulation occurred spontaneously within 5 wk postpartum. Estradiol (proestrus) and progesterone (12d postovulation) in plasma were also measured. Concentrations of insulin, IGF-1, glucose, fatty acids, and urea were determined in follicular fluid (wk 9), and the expression of LH receptor, estrogen receptor ß, cytochrome P450 aromatase, and plasma type glutathione peroxidase genes measured in granulosa cells obtained from the preovulatory follicles at wk 9 postpartum in the subset of 24 cows. Diets did not alter the interval from calving to first ovulation (32.3 ± 2.5d), but a significantly lower proportion of cows on the DDGS diet (20%) ovulated multiple (≥ 2) follicles at the first ovulation than those on the barley grain diet (40%). The incidence of multiple ovulations tended to be lower at first insemination (10 vs. 21% for cows fed DDGS and barley grain diets, respectively). Mean plasma concentration of insulin was higher in cows fed the barley grain diet (2.5 vs 1.6 IU/mL), and a diet by time interaction was noted, with cows on the barley grain ration having higher insulin from wk 6 to 12 postpartum; however, mean plasma IGF-1 concentration did not differ between dietary groups. In the subsets, mean plasma concentrations of metabolites or estradiol and progesterone were not affected by diet, parity, or diet by parity interactions. Cows on the DDGS diet had lower concentrations of IGF-I (69 vs. 108 ng/mL) and higher fatty acids (222 vs. 149 mEq/L) in the follicular fluid obtained from preovulatory follicles. Diet, parity, and diet by parity interactions did not affect the concentrations of insulin, glucose, urea, estradiol, and progesterone in follicular fluid. Diets did not alter the expression profiles of LHr, estrogen receptor ß, CYP19, and GPx3 genes in granulosa cells. In summary, diets did not affect the interval from calving to first ovulation or granulosa cell gene expression. However, reducing dietary starch content by a partial replacement of dietary grain with wheat DDGS increased fatty acids in follicular fluid and reduced the concentrations of insulin in plasma, IGF-1 in follicular fluid, and the incidence of multiple ovulations.

Ovulações múltiplas em éguas abatidas em Pelotas-RS / Multiple ovulation in slaughtered mares - Pelotas-RS

O presente trabalho descreve a frequência de ovulações múltiplas em 3631 éguas, abatidas em Pelotas - RS, durante o período de janeiro de 1988 a setembro de 1989, com a predominância de sangue da raça Crioula. A maior frequência de ovulações múltiplas ocorreu no mês de fevereiro (19 por cento), diminuindo progressivamente até setembro (0,4 por cento). Este resultado mostra que o fotoperíodo exerce uma influência positiva sobre a atividadc ovariana, inclusive no que tange ao número de ovulações por ciclo. A frequência média geral de ovulações múltiplas foi 7,1 por cento (257/3631). A taxa média de ovulações duplas foi de 6,5 por cento (235/3631), tripla de 0,5 por cento (19/3631) e quádrupla, 0,1 por cento (3/3631). Os meses de dezembro a abril mostraram as maiores frequências sobre o total das ovulações múltiplas (65,5 por cento). Estas informações podem representar um importante subsídio ao manejo reprodutivo da raça crioula, visando controlar o sério problema que as gestações gemelares representam na espécie equina.

This paper describes the frequency of multiple ovulations in 3631 mares, slaughtered in Pelotas - RS, predominantly from Crioulo breed. The higher frequency of multiple ovulation ocurred in February (19 percent), decreasing progressively up to September (0.4 percent). This result shows that the photoperiod has a positive influence on the ovarian activity, even on the number of ovulations per cycle. The overall mean of multiple ovulation was 7.1 percent (257/3631). Double ovulations ocurred in 6.5 percent (235/3631), triple in 0.5 percent (19/3631) and quadruple in 0.1 percent (3/3631). The months from December to April presented the highest frequencies over all multiple ovulations (65.5 percent). These observations may represent an importante support to reproductive management of the Crioulo breed in order to control the serious problem that represents twin pregnancies in equine.