Estrus Synchronization Protocol Research Articles

Conception Rate of Pre-synchronization and Two Short Term Heat-synch Programs using Two Doses of PGF2α in Lactating Holstein Dairy Cows

BACKGROUND: Improving the reproductive performance of dairy cows requires manipulation of estrus using estrus synchronization protocols. OBJECTIVES: The aim of this study was to evaluate the effect of reducing the length of estrus synchronization protocol by using two doses of prostaglandin injection on reproductive performance of Holstein dairy cows. METHODS: At first, all cows received GnRH (day 0), PGF2α on day 7, and GnRH on day 17. Then, cows assigned randomly to one of 3 groups: Group 1) PGF2α injection on days 22 and 23, estradiol benzoate injection on day 24. Group 2) PGF2α injection on days 23 and 24, estradiol benzoate injection on day 25. Group 3) Control group; injection of PGF2α on day 24, injection of estradiol benzoate on day 25. Estrus detection was performed twice a day up to 48 hours (AM/PM) using signs of estrus and fixed time AI protocol was used after 48 hours (if not previously inseminated). RESULTS: Conception rate in group 2 were significantly higher than control group (P≤ 0.05) and tended to be higher than group 1 (P= 0.079). CONCLUSIONS: The results confirmed the hypothesis that a decrease in the period of follicle dominance by reducing the interval between GnRH and PGF2α through using two injections of PGF2α improved fertility of lactating dairy cows.

Relationship of body maturation with response to estrus synchronization and fixed-time AI in Nelore (Bos indicus) heifers

The relationship between body maturation at puberty and pregnancy after fixed-time AI (FTAI) was investigated in young Nelore (Bos indicus) heifers. Heifers (n = 650; 13.9 ± 0.03 months; 252 ± 0.99 kg LW) were assessed for body condition score (BCS, scale 1–5), withers height (hWITHERS, cm), chest depth (cDEPTH), subcutaneous fat thickness (SCFT, mm), and the presence of a corpus luteum (puberty). Heifers then underwent a progesterone-based estrus synchronization protocol with FTAI, and pregnancy rate to AI (P/AI) was recorded. Data were analyzed by univariate and multivariate logistic regression using the GLIMMIX procedure of SAS 9.3 and Receiver Operating Characteristic (ROC) curves were used to ascertain the effects of variables on puberty and P/AI. BCS and hWITHERS were not related (P > 0.05) to either puberty or P/AI. cDEPTH had no relationship (P = 0.56) with puberty but influenced (P < 0.02) P/AI. A greater (P = 0.002) proportion of heifers with SCFT > 3.4 mm attained puberty and the P/AI was greater (P = 0.0003) for heifers with SCFT > 2.5 mm. The findings were interpreted to indicate that both puberty and the response to estrus synchronization-FTAI in young Nelore heifers are dependent on the acquisition of subcutaneous adipose tissue that is sufficient to support reproductive function. It was concluded that Nelore heifers selected and nutritionally managed for body maturation can achieve a pregnancy rate to FTAI at around 14 months of age that is similar with pregnancy rates in older heifers.

Pregnancy rate in ewes injected with zinc oxide during an estrus synchronization protocol

Objective: To measure the effect of zin injection, during an estrus synchronization protocol, on pregnancy rate in sheep from the “Valle de Mexicali”.Design/methodology/approach: The experimental units were 157 ewes, which wereallocated in five farms (UP): UP1 (n=19), UP2 (n=27) UP3 (n=20) UP4 (n=71) and UP5(n=21). In each farm, the ewes were randomly assigned to one of three treatments:control, z-100 and z-200. The ewes from control groups were subcutaneously injectedwith 4 mL of olive oil as placebo. The ewes from groups z-100 and z-200 weresubcutaneously injected with 100 and 200 mg of zinc oxide. The response variableswere the preovulatory diameter of the largest follicle and pregnancy rate.Results: The differences between experimental groups on diameter of the largestpreovulatory follicle and pregnancy rates were not significant different (p&amp;gt;0.05). Limitations of the study/implications: The ewe’s reproductive response to zincinjection might be affected by the animal mineral status, it is recommended to carry onsupplementation with base on mineral blood concentrations.Conclusion: The subcutaneous injection with 100 or 200 mg of zinc oxide did not affectthe size of the largest preovulatory follicle and pregnancy rate in ewes.

Evaluation of Ovsynch versus modified Ovsynch program on pregnancy rate in water buffaloes: a meta-analysis.

Ovsynch is a widely accepted estrus synchronization protocol for improving the reproductive performance of water buffaloes who manifest low reproductive efficiency. Recently, some modified protocols based on Ovsynch such as 2 injections of prostaglandin 14days apart following the Ovsynch are also introduced to enhance the reproductive potential of this species. In the present study, a meta-analytical assessment was performed with the objective to evaluate the reproductive performance of water buffaloes synchronized with Ovsynch or modified Ovsynch programs. Meta-analysis of the fixed or random effects model was determined by the heterogeneity among the studies. Reproductive outcome of interest was pregnancy per artificial insemination (P/AI) measured on day 25 (25-100). A total of 32 articles including 4003 buffaloes using either Ovsynch or modified Ovsynch protocol were reviewed. In the random effects model for buffaloes, the overall proportion of P/AI was 42.55% [95% confidence interval (CI): 37.48-47.70; n = 3,089] and 46.44% (95% CI: 39.63-53.31; n = 914) on day 25 after AI for Ovsynch and modified Ovsynch, respectively. Results for P/AI were then categorized by ovarian activity, where P/AI was available for 3575 cyclic buffaloes and 320 non-cyclic buffaloes. For cyclic buffaloes, the overall proportion of P/AI was 47.54% (95% CI: 42.72-52.38; n = 2911) and 57.97% (95% CI: 54.12-61.77; n = 664) on day 25 after AI for Ovsynch and modified Ovsynch, respectively. In the fixed effects model for non-cyclic buffaloes, the overall proportion of P/AI was 19.68% (95% CI: 13.48-26.58; n = 167) and 33.01% (95% CI: 25.50-40.94; n = 153) on day 25 after AI for Ovsynch and modified Ovsynch, respectively. In conclusion, a benefit for P/AI is detected in buffaloes with the modified Ovsynch protocol. Besides, whichever estrus synchronization protocols (Ovsynch or modified Ovsynch), cyclic buffaloes have higher P/AI compared with non-cyclic buffaloes.

Comparação entre dispositivos intravaginais de progesterona de primeiro e quarto uso para reprodução em bovinos

The intravaginal progesterone device is the most expensive of the estrus synchronization protocol, which may make it impossible for the producer to access this biotechnology. The aim of the present study was to compare the pregnancy rate between implants with new devices and fourth use in two farms in Amazonas. Data were acquired through the MultBovinos® program. The results show a pregnancy rate of 56.06% for new devices and 67.14% for fourth use on Farm 01 and 67.09% for new devices and 70.97% for fourth use on Farm 02. Therefore, the reuse of 1.9 g progesterone intravaginal implants obtained better pregnancy rate results when compared to the first use.

EFFECT OF KISPEPTIN-10 AS AN ALTERNATIVE TO ECG IN ESTRUS SYNCHRONIZATION PROTOCOL ON IMPROVING THE REPRODUCTIVE PERFORMANCE OF KARADI EWES

This study was conducted to examine the effect of Kisspeptin-10 as an alternative to equine chorionic gonadotropin (eCG) in estrus- synchronization protocol for improving the reproductive performance of Karadi ewes. Forty adult ewes of 3-7 years old and 65–70 kg live body weight were equally divided into four equal groups. Animals were inserted with a progestagen (60 mg MAP)-impregnated sponges for 13 days as estrus synchronization protocol. Following withdrawal of sponges, first group was served as control (C) and intramuscularly injected with normal saline only. The second group was intramuscularly injected with 250 IU of eCG (eCG), while those of third and fourth groups were intravenously injected with 4 and 8 µg /kg body weight of Kisspeptin-10, referred as Kisspeptin1 and Kisspeptin2 groups respectively. Serum progesterone and LH concentrations did not significantly differ among groups before estrus synchronization protocol and eCG or Kisspeptin treatments. The two Kisspeptin-injected groups attained better (P≤0.01) overall mean estrus (100%), fertility (90%), conception (90 and 100%, respectively), lambing (90%), and twinning (10%) rates with lesser barrenness (10%) as compared with the other groups. Moreover, eCG and Kisspeptin groups exhibited greater (P≤ 0.01) percentage of increasing fecundity (233%) and extra lambs born (0.7) than the control group. In conclusion, treatment of Karadi ewes either with Kisspeptin-10 or eCG hormones enhanced the overall reproductive performance, but did not affect serum progesterone and LH concentrations.

NEGATIVE EFFECTS OF BEDDING AND LYING AREA ON SYNCHRONIZED ARTIFICIAL INSEMINATION IN DAIRY CAWS IN SARAJEVO KANTON

Dairy cattle breeding is one of the most important branches of livestock production, which has been facing, for several decades, the chronic problem of declining reproductive performance. In 2005, the number of cattle worldwide was about 1,370,000,000, while in 2015 that number dropped below one billion, and in 2021 it shows a slight recovery as it was 1,000,970. This indicates the importance of applying different reproductive protocols in order to increase the number of cows in production. The type of bedding on which the animals stay, as well as the characteristics of the lying area itself, shows a significant impact on numerous physiological functions such as food intake, chewing, milk yield, but also levels of sex hormones. The type of bedding and lying area, which causes chronic pain and stress, leads to disorders of physiological and reproductive processes, since stress has direct negative impact on numerous cellular functions. A total of 66 dairy cows, 50 Holstein-Friesian cows kept on PD Butmir and 16 Simmental cows kept on a private mini farm, were included in the study. At PD Butmir, cows were kept in tie-stall housing system, while on a mini-farm they were kept free. Hormonal protocols of estrus and ovulation synchronization were used in April, May and June 2019. Cows were subjected to two estrus synchronization and ovulation protocols, Ovsynch and Cosynch72. At PD Butmir, 25 cows were subjected to Ovsynch and Cosynch72 protocols, respectively. At the mini-farm only Ovsynch protocol was applied. The Ovsynch protocol applied on PD Butmir had success in conception rate of 12% (n = 3), while the Cosynch72 protocol gave a score of 36% (n = 9). On the mini-farm, Ovsynch resulted in a conception of 25% (n = 4). Based on our results, the Cosynch72 protocol, compared to the Ovsynch protocol, was a better choice in the case of Holstein-Friesian cows kept in the tie-stall housing system. In the Simmental cows kept in the free stall system, the Ovsynch protocol proved to be better choice in achieving conception, compared to the Holstein-Friesian cows. Therefore, it is necessary to test several different protocols of estrus and ovulation synchronization, in order to find the most optimal one for a certain breed, type of keeping and breeding.

Heterologous beta-nerve growth factor (β-NGF) given at the LH surge enhances luteal function in dairy heifers

Genetic selection for high yield milk production has led to a decline in dairy cattle's reproductive performance over the last 40 years. Low progesterone (P4) plasma content following ovulation is associated with suboptimal fertility in dairy cattle. Several pieces of evidence indicate that the protein beta-nerve growth factor (β-NGF) that is present in the male seminal plasma exerts potent ovulatory and luteotrophic effects following systemic administration in camelids but also in other species. In this study, we determine whether systemic administration of purified llama β-NGF given at the induced preovulatory luteinizing hormone (LH) peak improves corpus luteum (CL) function in dairy heifers subjected to an estradiol (E2) / P4 estrus-synchronization protocol. To achieve this, we first determined plasma E2 and LH hormone profiles to establish the timing of the estradiol benzoate (EB)-induced LH peak in estrus-synchronized heifers. Then, we tested whether the administration of β-NGF given at the end of this peak affects the CL and its function by analyzing diameter, vascular area, and P4 output. Our results show that, with the estrus-synchronization protocol applied, plasma LH concentrations peaked (P < 0.01) 40-h and 16-h after removal of the bovine intravaginal device (DIB; containing 1.0 g of P4) plus cloprostenol injection and subsequent EB administration, respectively; after peaking, plasma LH concentrations remained stable for the next 8-h to then return to basal levels. Heifers synchronized with this protocol and receiving a dose of 1 mg of β-NGF at the end of the LH peak (ie, 48-h after DIB removal) did not show significant differences in CL diameter, but these exhibited a greater CL vascular area (P = 0.01) than the observed in vehicle-injected heifers. Furthermore, plasma P4 concentration in β-NGF-treated heifers was higher (P = 0.001) than those quantified in vehicle-injected heifers. These results support the use of β-NGF in estrus-synchronization protocols to improve the early luteal function in dairy heifers.

Estradiol Priming Potentiates the Kisspeptin-Induced Release of LH in Ovariectomized Cows.

Simple SummaryThe magnitude and duration of the pre-ovulatory release of LH is important in controlling the timing of ovulation in estrus synchronization and fixed-time artificial insemination (FTAI) protocols in cows. The neuropeptide kisspeptin (KISS1) stimulates GnRH neurons in the brain which in turn induce LH release from the pituitary gland. The present study used ovariectomized Nelore cows as a model to examine whether priming with the steroid estradiol benzoate (EB) for 12 h increased both the peak and duration of LH release after treatment with KISS1. It was found that cows pre-treated with EB for 12 h showed a greater LH peak and longer duration of LH release in response to KISS1 compared with cows that received EB at the same time as KISS1, or KISS1 alone. The incorporation of EB priming and KISS1 in estrus synchronization-FTAI protocols could improve the control of LH release and ovulation, and potentially increase fertilization and conception rates in cows. This would have important practical application in assisted breeding in beef and dairy cows.The present study examined whether priming with estradiol benzoate (EB) for 12 h increased both the peak and duration of LH release in response to kisspeptin (KISS1, KP) in cows. In a Latin square design, ovariectomized Nelore cows (n = 8) received: Control, i.m. 4 mL of 0.9% saline; KP, i.m. 4 mg murine KISS1-10; EBKP, i.m. 4 mg KISS1-10 + i.m. 2 mg EB simultaneously; EB12KP, i.m. 4 mg KISS1-10 + i.m. 2 mg EB 12 h before KISS1-10. Concentrations of LH were determined in blood samples obtained at time 0 (treatment), 20, 40, 60, 90, 120, 150, 180, 210 and 270 min. Concentrations of LH were analyzed by Proc GLIMMIX for repeated measures. In case of significance, the adjusted Tukey test was used to test for differences among treatments. GraphPad 8.0 PRISM® was used to determine the area under the LH-response curve (AUC) after injection of KISS1-10. Plasma LH remained relatively constant throughout sampling after treatment with saline. The peak in LH after injection of KISS1-10 occurred at 20 min in Groups KP and EBKP and at 40 min in Group EB12KP. The peak LH response (∆LH, ng/mL) was greater (p < 0.01) in Group EB12KP (5.6 ± 0.9) than in Groups KP (2.4 ± 0.9) and EBKP (3.5 ± 0.9), which did not differ. AUC (LH ng/mL*min) was greater (p = 0.02) in Group EB12KP (439 ± 73) than in Groups KP (176 ± 73) and EBKP (241 ± 73), with the latter two groups not differing. The findings indicated that 12 h priming with EB increased both the peak and duration of the LH response to treatment with KISS1. The incorporation of EB priming and KISS1 could improve the efficiency of estrus synchronization with fixed-time AI in cows. This would have an important practical application in assisted breeding in beef and dairy cattle.

RESPUESTA REPRODUCTIVA EN OVEJAS DE PELO SINCRONIZADAS CON ACETATO DE MEDROXIPROGESTERONA IMPREGNADO EN ESPONJAS INTRAVAGINALES NO COMERCIALES

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; Intravaginal sponges impregnated with medroxyprogesterone acetate or fluorogestone acetate are routinely used in oestrus synchronization protocols in sheep, non-commercial sponges are a viable option in the reproductive control of female sheep.&lt;strong&gt; Objective.&lt;/strong&gt; To evaluate the reproductive response in hair sheep synchronized with medroxyprogesterone acetate impregnated in non-commercial intravaginal sponges. &lt;strong&gt;Methodology.&lt;/strong&gt; 31 adult hair sheep 5/8 Pelibuey x 2/8 Black Belly x 1/8 Dorper, average weight of 40 ± 3.2 kg and a body condition of 3-3.5 were used. They were randomly assigned to one of four treatments: T1 (n = 8 ewes), 5 mg of medroxyprogesterone acetate impregnated in non-commercial intravaginal sponges + 1 mg of estradiol cypionate + 200 IU of eCG; T2 (n = 8 ewes), synchronization similar to T1, but 500 IU of eCG were applied; T3 (n = 8 ewes), 20 mg of fluorogestone acetate impregnated in intravaginal sponges + 200 IU of eCG; T4 (n = 7 ewes), synchronization similar to T3, but 500 IU of eCG were applied. In all treatments the sponges were placed for 10 days. Blood samples were collected by jugular puncture and the concentrations of progesterone and LH were determined. &lt;strong&gt;Results.&lt;/strong&gt; The sponge removal interval to estrus was different (P &amp;lt;0.05) between T1 and T3 (14.5 ± 5.5 and 38.8 ± 2.5 h, respectively). Estrus duration was similar (P&amp;gt; 0.05) between T1, T2 and T3 (54.5 ± 5.5, 46.5 ± 5.8 and 38.3 ± 2.6 h, respectively), T4 (59.3 ± 4.1 h) was similar (P&amp;gt; 0.05) to T1 and T2 (54.5 ± 5.5 h and 46.5 ± 5.8 h, respectively) but different (P &amp;lt;0.05) from T3 (38.3 ± 2.6 h). The progesterone concentration was higher than 1 ng ml&lt;sup&gt;-1&lt;/sup&gt;, on days 0 to 4 (T2), 0 to 5 (T4) and 0 to 7 (T1 and T3), then it decreased to &amp;lt;1 ng ml&lt;sup&gt;-1&lt;/sup&gt; in all the treatments. The sponge removal and oestrus onset intervals at the LH preovulatory peak were similar (P&amp;gt; 0.05) between treatments, however, the LH profile at T1 and T2 shows scattered elevations. 5 mg of medroxyprogesterone acetate + 1 mg of estradiol cypionate, impregnated in non-commercial sponges advance oestrus and do not adjust for the occurrence of LH preovulatory peak.&lt;strong&gt; Implications. &lt;/strong&gt;The study demonstrates that it is feasible to use reduced doses of medroxyprogesterone acetate impregnated in non-commercial intravaginal sponges in estrous synchronization protocols in hair sheep, the progesterone profile confirms the inhibitory effect of the drug on GnRH / LH secretion.&lt;strong&gt; Conclusion. &lt;/strong&gt;The application of 200 or 500 IU of eCG does not modify the occurrence or duration of estrus and the LH preovulatory peak. It is suggested that it is feasible to synchronize hair sheep under tropical conditions with reduced doses of medroxyprogesterone acetate impregnated in non-commercial sponges, however, dispersion of ovulation may occur, which would reduce fertility. The use of eCG and estradiol cypionate does not affect the effectiveness of synchronization.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;

Effect of eCG in a short-term synchronization treatment on ovarian status, estrus synchrony, and ovulation in dairy goats managed under tropical conditions.

The aim of this study was to assess the need of using eCG on short-term estrus synchronization protocol in nulliparous (NUL) and multiparous (MULT) dairy goats during the breeding season. Alpine (n = 20), Nubian (n = 20), and Saanen (n = 16) goats received 60 mg medroxyprogesterone acetate intravaginal sponges for 6 days plus 30 μg d-cloprostenol and 200 IU eCG (G-eCG, n = 28) or saline (G-Control, n = 28) 24 h before sponge removal. The NUL and MULT goats of each breed were equally assigned into the two treatments. Transrectal ultrasonography was used to evaluate ovulatory parameters, and teaser goats were used for estrus detection every 12 h from sponge removal to ovulation. eCG did not affect (P > 0.05) estrus response (~86%), diameter of ovulatory follicles (~6.8 mm), and number of ovulations (~1.6). Nevertheless, eCG led to earlier (P < 0.05) ovulation (G-eCG = 65.1 and G-Control = 73.2 h) and increased (P < 0.05) the ovulation rate (G-eCG = 96.4% and G-Control = 67.9%). In the absence of eCG, no differences regarding reproductive parameters (P > 0.05) were found between parity orders. Alpine MULT goats underwent a superior (P < 0.05) number of ovulations (2.2) in comparison to NUL goats (1.3). In conclusion, the exclusion of eCG from short-term estrus synchronization protocol did not interfere with estrus response but decreased the ovulation rate.

Effects of prolonging the interval from progestin removal to prostaglandin F2α injection from 16 to 17 d in a long-term estrus synchronization protocol in beef heifers.

To determine effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG protocol, 1,049 Angus heifers at six locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to one of two treatment groups: 1) PG16 (n = 518), heifers received a controlled internal drug release (CIDR) insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal (d 30), and a 100-µg injection of gonadotropin-releasing hormone concurrent with TAI 66 ± 2 h later; or 2) PG17 (n = 531), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal (d 31), and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to a subset (n = 482) of heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 116). Transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI differed by treatment where PG17 heifers had greater (P < 0.01) expression of estrus than PG16 heifers (57.8 ± 6.1% vs. 43.4 ± 6.1%, respectively). Nevertheless, dominant follicle diameters at PGF and at TAI were similar (P ≥ 0.59) between PG16 and PG17 heifers. In addition, PR/AI did not differ (P = 0.29) between PG16 and PG17 treatments (50.5 ± 3.2% vs. 45.7 ± 3.1%, respectively). Results of this experiment indicate that delaying the injection of PGF and TAI in the 14-d CIDR-PG protocol increased estrus expression prior to TAI yet did not improve fertility in beef heifers.

Influence of Different Synchronization Protocols on Fertility Response in Surti Does

This study was carried out to assess the influence of different estrus synchronization Protocols on fertility response in Surti does based on litter size, fecundity and twining rate. Thirty does were selected and divided into five equal groups (n=6 in each). Does of G1 group were treated with intra-vaginal progestagen sponges (IVPS) for 11 days. Does of G2 group received the same IVPS sponge for 11 days and exposure of sexually active apronized buck during the treatment period. Does of G3 group were treated as per G1 group along with i/m injection of PGF2andalpha; analog (125 µg, Cloprostenol) at the time of sponge removal. Does of G4 group were subjected to the buck effect and exposed to a sexually active patronized buck for 11 days, and does of G5 group was kept as a control without any treatment for 11 days. It was found that, none of the synchronization Protocols had significant effect on litter size, fecundity, and incidence of multiple kid birth and sex ratio in Surti does.

NonSurgical Embryo Recovery from Estrus-Synchronized or Superovulated Morada Nova Ewes: A Feasible Strategy for Sheep Embryo Banking.

This study assessed the feasibility of in vivo embryo production and nonsurgical embryo recovery (NSER) in Morada Nova ewes (an endangered native Brazilian breed of sheep) subjected to different estrus synchronization and/or superovulation protocols. Ewes received intravaginal sponges soaked with 60 mg medroxyprogesterone acetate (MAP), which were kept in place for six (G6; n = 12), nine (G9; n = 12), or 12 (G12; n = 12) days. Half of the ewes in each group remained estrus synchronized only (SYNCH) and the other half was superovulated (SOV) with 133 mg porcine follicle-stimulating hormone (pFSH). There were no differences (p > 0.05) in antral follicle counts determined with ultrasonography 60 hours before MAP sponge removal (or at the time of the first pFSH dose) among G6 (6.4 ± 0.9), G9 (6.2 ± 0.7), and G12 (5.5 ± 0.6). Estrus responses and NSER success rates did not vary (p > 0.05) among the three progestin-treatment groups of ewes for either estrus-induced or superovulated animals. The onset of estrus occurred 10-12 hours later (p < 0.01) in G9SYNCH ewes compared with G6SYNCH and G12SYNCH, and the duration of estrus was ∼19 hours greater (p < 0.01) in G9SOV than in G6SOV. The average duration of the NSER procedure was 32.6 ± 1.3 minutes. At least one structure was recovered in 85.7% of synchronized and in 87.5% of superovulated ewes. Viable embryo recovery rates were also similar (p > 0.05) for G6 (1.0 ± 0.3 and 2.5 ± 1.5), G9 (1.3 ± 0.5 and 4.8 ± 2.0), and G12 groups (1.0 ± 0.3 and 4.8 ± 2.3; estrus-synchronized and superovulated ewes, respectively). In conclusion, progestogen pretreatment of different durations and NSER can be employed in Morada Nova ewes, resulting in reasonable viable embryo recovery rates in both estrus-synchronized and superovulated animals. Therefore, both techniques are suitable for use in commercial settings as well as small ruminant conservation programs.

Relationship among serum metabolic hormones with pregnancy rates to fixed-time artificial insemination in Bos indicus beef females

Two experiments compared body parameters and serum concentrations of GH, IGF-I, and leptin in Bos indicus females based on their pregnancy status to fixed-time artificial insemination (FTAI). In Exp. 1, 226 nulliparous heifers were assigned to a puberty induction protocol (d -35 to d -23), followed by an estrus synchronization and FTAI protocol (d -11 to 0). Heifers received a controlled internal progesterone releasing insert (CIDR) previously used three times on d -35, followed by 0.6 mg of estradiol cypionate and CIDR removal on d -23. Heifers received 2 mg of estradiol benzoate and a CIDR previously used twice on d -11, 12.5 mg of dinoprost tromethamine in addition to CIDR removal, 0.6 mg of estradiol cypionate and a 200 IU of eCG on d -2, followed by FTAI on d 0. Heifer BW and BCS were recorded on d -35, -11, and 30, whereas blood samples were collected on d -35, -23, -11, 0, and 30. In Exp. 2, 821 multiparous lactating Nelore beef cows were assigned to the estrus synchronization and FTAI protocol described in Exp. 1, but received 300 IU of eCG on d -2. Cow BW and BCS were recorded on d -11 and 30, and blood samples were collected on d -11, 0, and 30. In both experiments, pregnancy status was verified via transrectal ultrasonography on d 30. In Exp. 1, heifers that became pregnant had greater (P = 0.03) IGF-I concentrations on d 0 and less (P = 0.05) IGF-I concentrations on d 30 compared to heifers that did not become pregnant (pregnancy status × day; P < 0.01). No differences in BW, BCS, GH and leptin were detected (P ≥ 0.23) according to heifer pregnancy status. In Exp. 2, cows that became pregnant had less (P = 0.03) leptin concentrations on d -11, and less (P = 0.01) IGF-I concentrations on d 30 compared to cows that did not become pregnant (pregnancy status × day; P ≤ 0.05). No differences in BW, BCS, and GH were detected (P ≥ 0.15) according to cow pregnancy status. In summary, serum leptin at the beginning of estrus synchronization was negatively associated with pregnancy rates to FTAI in multiparous cows. A negative relationship was also observed between serum IGF-I during early gestation with pregnancy rates to FTAI across parities. These results provide novel insights on the relationships among metabolic hormones with reproductive performance of B. indicus females.

Effect of different estrus synchronization protocols on estrus and pregnancy rates, oxidative stress and some biochemical parameters in Hair goats

The aim of this study was to investigate the relationship between different estrus synchronization protocols, some fertility parameters and serum biochemical parameters including total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), thyroid stimulating hormone (TSH), estradiol (E2) and progesterone (P4) in Hair goats. The study was carried out on 150 female Hair goats during the breeding season. Goats were divided into three groups as control (n = 50), short-term (n = 50) and long-term (n = 50) groups. Control group did not receive any treatment, short-term group received intravaginal P4 (7 d) combined with GnRH (on days 0 and 9) and PGF2α (on day 7), and long-term group received intravaginal P4 (12 d) combined with pregnant mare's serum gonadotropin (on day 12) and GnRH (on day 13). In control group, blood samples were collected at the beginning (first measurement) and 7th day (second measurement) of the study. In short-term and long-term groups, blood samples were collected at the time of sponge insertion (first measurement) and withdrawal (second measurement). Serum TAS, TOS, P4, E2, TSH levels were measured on all sampling days, and OSI was calculated. All the groups were observed for estrus behavior and those showing the signs of estrus were allowed for mating. Transrectal ultrasound examination was performed to diagnose pregnancy approximately 40 days after mating. The onset of estrus was earlier in short-term group compared to long-term group (P < 0.001). The estrus and pregnancy rates were significantly higher in short-term group compared to other groups (P < 0.05). At the time of first measurement, E2 level in short-term group and P4 level in long-term group were higher and lower than the other groups, respectively (P < 0.05). At the time of second measurement, TAS, TOS, OSI and E2 levels were significantly different in short-term group compared to control and long-term groups (P < 0.01). Additionally, P4 level in control group and TSH level in long-term group increased (P < 0.01). While TAS level in short-term group and E2 level in all groups increased from the first measurement to the second measurement, the TOS and OSI values decreased (P < 0.01). TSH level in short-term group decreased from the first measurement to the second measurement (P < 0.01), while it increased in long-term and control groups (P < 0.05). In conclusion, it was obtained that synchronization protocols can affect serum TAS, TOS, E2, P4, TSH and OSI levels; and short-term intravaginal P4 treatment combined with GnRH and PGF2α clearly improved the antioxidant defense system and increased fertility parameters in Hair goats.

Efficacy of Pre-Synchronization and CIDR on the Outcome of Short-TermSynchronization Program in Zandi Ewes During the Breeding Season

BACKGROUND: Timed breeding programs are essential to implementing extensive artificial insemination (AI) programs in sheep. OBJECTIVES: This study aimed to evaluate whether application of pre-synchronization and controlled internal drug releasing (CIDR) before and during fixed time AI protocol, respectively, could enhance estrus synchronization and fertility of ewes. METHODS: A total of 120 ewes were randomly assigned into four experimental groups (n=30 in each group) considering age, weight, and body condition score (BCS). All ewes received GnRH (25 μg of alarelin acetate), and five days afterwards, PGF2α (75 μg d-cloprostenol) plus eCG (400 IU). In the control group, ewes received no additional treatment. In Pre-synch group, ewes received two injections of PGF2α at 9-day interval three days before GnRH administration of main estrus syn-chronization protocol. In CIDR group, ewes received 5-day CIDR between GnRH and PGF2α of main estrus synchronization protocol. In Pre-synch-CIDR group, ewes received both two injections of PGF2α at 9-day interval and 5-day CIDR. Blood serum progesterone concentrations were measured in all ewes prior to injection of PGF 2α (day 5). All ewes were subjected to fixed time laparoscopic AI 48 hours after administration of the last PGF 2α. RESULTS: No interaction was found between CIDR and pre-synchronization protocols (p >0.05). Progesterone concen-tration was higher in the CIDR groups than in groups without CIDR (p 0.05). The estrus was earlier in ewes with pre-synchronization compared to ewes without pre-synchronization following the last injection of prostaglandin (p =0.022). Pregnancy rate, lambing rate, prolificacy rate, fecundity rate, lamb weight at birth, and lamb gender were not significantly different between the treatment groups (p >0.05). CONCLUSIONS: In our study, estrus rate and reproductive parameters showed no significant differences between dif-ferent groups, although pre-synchronization advanced onset of estrus expression.

Effect of GnRH treatment following a short-term estrous induction protocol on estrus and ovulation in Saanen goats, during the transitional period

The objective of this study was to compare the effect on the ovulation time and estrus parameters of a GnRH agonist (buserelin acetate) administered 24 or 36 h following a short-term estrus induction and synchronization treatment in non-lactating Saanen goats during the transitional period. Goats received 20 mg FGA sponges for 6 days plus 300 IU eCG and 125 μg d-cloprostenol 24 h prior to sponge removal. After removal of the sponges, goats were given either 1 ml physiological saline (0.9% NaCI) solution (Group1; n = 9) after 12 h, 0.004 mg GnRH (Group2; n = 10) after 24 h or 0.004 mg GnRH (Group3; n = 10) after 36 h. The follicle development and ovulation in the ovaries were monitored by transrectal ultrasonography starting from the sponge application until the fifth day of the estrus cycle. Blood samples were collected on the same days to determine the plasma concentrations of progesterone (P4) and estradiol (E2). No statistical differences among groups were detected in any synchronization parameters, ultrasonic evaluations and plasma P4 and E2 concentrations. The evaluation of pooled data showed that the response of Saanen goats to treatments was comparable to the results of other published trials. Results of this study indicate that administration of GnRH at 24 h or 36 h after sponge removal, at the end of a short estrus induction and synchronization protocol, does not affect plasma P4 and E2 concentrations, estrus parameters and ovulation time in goats, during the transition period.

Ovarian Follicular Dynamics, and Hormonal and Biochemical Profile in Post-Pubertal and Postpartum Jaffrabadi Buffaloes

Jaffrabadi buffalo is one of the heaviest buffalo breeds of the world (800 kg) and is known for poor reproductive efficiency. There is a scarcity of normal physiological data regarding reproductive parameters of Jaffrabadi buffalo. The primary objective of this study was to elucidate ovarian follicular dynamics, hormonal and biochemical profiles in 10 post-pubertal heifers (n=5 each of age 42±2 and 48±2 months) and five &gt;90 days postpartum lactating buffaloes. Ultrasound monitoring of ovaries of animals was done at weekly interval and all follicles with diameter less than 4 mm (small follicles), 4-8 mm (medium follicles) and greater than 8 mm (large follicles) as well as CLs identified were recorded. Blood samples were also collected soon after each USG from all animals for assay of hormonal and biochemical profiles. The findings revealed that the average number of small, medium and large follicles, total number of follicles per ovary as well as diameters of largest and subordinate follicles varied greatly among periods between three groups. The size of corpus luteum ranged from 13.7 to 21.2 mm, 13.7 to 23.9 mm and 15.3 to 22.7 mm, respectively, in Group-I, II and III. In the first week of study, significantly higher (p less than 0.05) average numbers of small follicles in Group-I and III, and medium follicles and total numbers of follicles in Group-III were observed as compared to other groups. The diameter of largest follicles and subordinate follicles were non-significantly different among all groups at all periods of the study. Plasma estrogen levels were significantly higher (p less than 0.05) in Group-I as compared to Group-III and Group-II on first and second week, however, it increased significantly (p less than 0.05) in Group-II and I on fourth week of study period. Plasma insulin concentrations were significantly (p less than 0.01) lower in buffaloes (Group-III) than in heifers (Group-I and II) throughout the study period, while plasma total cholesterol and total protein levels were higher in Group-III on 3rd to 5th weeks of study. Further, there were no significant differences in the plasma FSH, LH, progesterone and blood glucose levels in animals of three groups between periods at any of the week. The ultrasonographic and endocrine profile suggested establishment of cyclicity with silent ovulation. However, the behavioural estrus was still not manifested by these post-pubertal heifers and postpartum lactating buffaloes. These results are helpful to diagnose anovulatory conditions and/or true anestrus and initiate estrus synchronization protocols for early conception in Jaffrabadi buffaloes.

Effects of nutrient restriction on the metabolic profile of Bos indicus-influenced and B. taurus suckled beef cows

Recent research from our group demonstrated that Bos indicus-influenced suckled beef cows had greater resilience to withstand nutrient restriction and establish pregnancy compared with B. taurus cows exposed to the same conditions. To further understand these findings, differences in metabolic profile between these same B. indicus-influenced and B. taurus females were explored. Suckled beef cows (n = 134) were enrolled in a completely randomized design with a 2 × 2 factorial arrangement of treatments. On day −21, Angus (AN; Bos taurus) and Brangus (BN; B. indicus-influenced) cows were randomly assigned to 1) a diet that met daily energy maintenance requirements (MAINT), or 2) a diet that restricted intake to 70% of the daily energy maintenance requirements (RESTR). Cows were exposed to an estrus synchronization protocol and received an embryo 7 d after ovulation was pharmacologically induced on day 0. Blood samples were collected on days −21 and 19 to determine circulating concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), insulin, glucose, and IGF-1. Pregnancy status after embryo transfer was determined on day 28. As a consequence of the proposed diets, cows in the RESTR diet had less body condition score (BCS) on day 19 (P = 0.008) across breed types. Moreover, BCS change from day −21 to 19 was included as independent covariate into subsequent analyses, allowing for the comparison of breed types under an equivalent level of body reserve mobilization. A breed × diet interaction was observed for plasma insulin (P = 0.03) and IGF-1 (P = 0.04) on day 19, where AN–RESTR cows had less plasma concentrations on day 19 compared with AN–MAINT cows. Diets did not impact (P > 0.10) plasma insulin and IGF-1 concentrations in BN cows. No diet or breed effects were observed in circulating concentrations of NEFA, BHB, and glucose (P > 0.10). Across breed types and nutritional treatment, there was positive linear effect (P ≤ 0.04) of plasma concentrations of insulin and IGF-1 on the probability of pregnancy to fixed-time embryo transfer. In summary, the negative impacts of nutrient restriction on the somatotropic axis, independently of body tissue mobilization, were heightened in Bos taurus females compared with B. indicus-influenced cohorts, which corroborate with the differences observed in fertility between these subspecies.