José Nélio de Sousa Sales

Effects of two estradiol esters (benzoate and cypionate) on the induction of synchronized ovulations in Bos indicus cows submitted to a timed artificial insemination protocol

The effects of estradiol benzoate (EB) and estradiol cypionate (EC) on induction of ovulation after a synchronized LH surge and on fertility of Bos indicus females submitted to timed AI (TAI) were evaluated. In Experiment 1, ovariectomized Nelore heifers were used to evaluate the effect of EB (n = 5) and EC (n = 5) on the circulating LH profile. The LH surge timing (19.6 and 50.5 h; P = 0.001), magnitude (20.5 and 9.4 ng/mL; P = 0.005), duration (8.6 and 16.5 h; P = 0.001), and area under the LH curve (158.6 and 339.4 ng/mL; P = 0.01) differed between the EB and EC treatments, respectively. In Experiment 2 (follicular responses; n = 60) and 3 (pregnancy per AI; P/AI; n = 953) suckled Bos indicus beef cows submitted to an estradiol/progesterone-based synchronization protocol were assigned to receive one of two treatments to induce synchronized ovulation: 1 mg of EB im 24 h after progesterone (P4) device removal or 1 mg of EC im at P4 device removal. There was no difference (P > 0.05) between EB and EC treatments on follicular responses (maximum diameter of the ovulatory follicle, 13.1 vs. 13.9 mm; interval from progesterone device removal to ovulation, 70.2 vs. 68.5 h; and ovulation rate, 77.8 vs. 82.8%, respectively). In addition, P/AI was similar (P < 0.22) between the cows treated with EB (57.5%; 277/482) and EC (61.8%; 291/471). In conclusion, despite pharmacologic differences, both esters of estradiol administered either at P4 device removal (EC) or 24 h later (EB) were effective in inducing an LH surge which resulted in synchronized ovulations and similar P/AI in suckled Bos indicus beef cows submitted to TAI.

Importance of estrus on pregnancy per insemination in suckled Bos indicus cows submitted to estradiol/progesterone-based timed insemination protocols.

The objective was to evaluate the effect of estrus occurrence (based on removal of tail-head marks) on ovarian responses and pregnancy per AI (P/AI; 30 d after AI) in suckled Bos indicus beef cows submitted to timed AI (TAI) protocols. Cows received an intravaginal device containing 1.0 g progesterone, and 2.0 mg estradiol benzoate im; 8 d later, the intravaginal device was removed, and they were given PGF(2α) (0.25 mg of cloprostenol sodium) and 300 IU of eCG, with TAI 48 to 52 h later. In Experiment 1, cows were assigned to receive one of three treatments: 1 mg of estradiol cypionate (ECP) im at progesterone (P4) device removal (N = 178); 10 μg of GnRH im at TAI (N = 190); or both treatments (N = 172). In cows given estradiol (ECP or ECP + GnRH), more displayed estrus (P = 0.002) and became pregnant (P < 0.0001) compared with those receiving only GnRH. In Experiment 2, the effect of the occurrence of estrus on ovarian responses was evaluated in cows (N = 53) synchronized using ECP at device removal. Cows that displayed estrus had a greater diameter of the largest follicle (LF) at device removal (P < 0.0001), a greater diameter at TAI (P < 0.0001), a greater ovulation rate (P = 0.02), a larger CL (P = 0.02), and a greater P4 concentration (P < 0.0001) than cows that did not display estrus. In Experiment 3, the effect of GnRH treatment on P/AI at TAI was evaluated in cows that received ECP at device removal, and either displayed, or did not display, estrus (N = 726). There was no estrus by GnRH interaction (P = 0.22); the P/AI was greater (P < 0.0001) in cows that displayed estrus (61.9%) than cows that did not display estrus (41.4%). However, GnRH did not improve (P = 0.81) P/AI (GnRH = 53.7% vs. no GnRH = 52.6%). In conclusion, exogenous estradiol at device removal increased both the proportion of suckled Bos indicus cows that displayed estrus and P/AI. Cows that displayed estrus had better ovarian responses (i.e., larger follicles at TAI, a greater ovulation rate, larger CL, and greater P4 concentrations) following an estradiol/P4-based synchronization protocol. Although occurrence of estrus improved pregnancy outcomes, GnRH at TAI did not improve P/AI in suckled Bos indicus cows treated with ECP, regardless of estrus occurrence.

Growth, metabolic status and ovarian function in buffalo (Bubalus bubalis) heifers fed a low energy or high energy diet

The aim was to establish the capacity of buffalo heifers to adapt their metabolic requirements to a low energy diet. Murrah buffalo (Bubalus bubalis) heifers undergoing regular estrous cycles were randomly assigned by age, live weight (LW) and body condition score (BCS) to a high energy group (HE, 5.8 milk forage units (MFU)/day, n=6) or low energy group (LE, 3.6 MFU/day, n=6). Circulating concentrations of metabolic substrates, metabolic hormones and reproductive hormones were determined weekly for 19 weeks. Ovarian follicular characteristics and oocyte parameters were also ascertained weekly. Heifers fed the LE diet had a better dry matter conversion than heifers fed the HE diet and the calculated daily energy provision was negative for heifers fed the LE diet (-0.248 MFU) and positive for heifers fed the HE diet (5.4 MFU). Heifers fed the HE diet had an increase in 50 kg LW over the duration of the study whereas LW remained constant for heifers fed the LE diet. The BCS of heifers fed the HE diet (4.2) was greater (P<0.05) than the BCS for heifers fed the LE diet (3.4). Heifers fed the HE diet had greater (P<0.05) circulating concentrations of metabolic substrates (glucose, total cholesterol and HDL cholesterol) and metabolic hormones (insulin, glucagon, leptin and T3) compared with heifers fed the LE diet. There were no significant differences in circulating reproductive hormones between the two groups of heifers. Ovarian follicular characteristics were similar for the two groups of heifers while heifers fed the LE diet tended to have oocytes of reduced quality compared with heifers fed the HE diet. The most notable finding was that heifers fed the LE diet had a negative calculated daily energy provision but were able to maintain LW and reproductive activity. It was concluded that buffalo heifers may potentially have the capacity to undergo metabolic adjustment and reduce their energy requirements when dietary energy is limiting. This adaptive capacity would explain why buffaloes remain productive in environments that are limiting to other ruminants.

Effect of circulating progesterone concentration during synchronization for fixed-time artificial insemination on ovulation and fertility in Bos indicus (Nelore) beef cows

Four experiments were designed to evaluate the effect of different circulating progesterone (P4) concentrations during a synchronization of ovulation protocol for the timed artificial insemination (TAI) of Bos indicus (Nelore) beef cattle. In the first trial, 13 ovariectomized Nelore heifers were randomly allocated into one of three groups using new P4 devices (New; 1.0xa0g P4), previously used P4 devices for 8xa0days (Used1x), and previously used P4 devices for 16xa0days (Used2x), in a crossover experimental design. The circulating P4 concentrations during the P4 device treatment were lower for Used1x (2.3xa0±xa00.1xa0ng/mL) and Used2x (2.0xa0±xa00.1xa0ng/mL) than those for New (3.8xa0±xa00.2xa0ng/mL; Pxa0=xa00.001). In the second trial, the ovarian follicular dynamics of 60 anestrous cows were evaluated after the cows received the treatments described previously (New [nxa0=xa020], Used1x [nxa0=xa020], and Used2x [nxa0=xa020]). During the insertion of the P4 device, the cows were administered 2.0-mg estradiol benzoate. Eight days later, the P4 device was removed, and the cows were administered 0.53-mg sodium cloprostenol, 300 IU eCG, and 1-mg estradiol cypionate. There were no differences among the groups during the interval from P4 device removal to ovulation (73.7xa0±xa02.9 vs. 69.8xa0±xa02.4 vs. 68.4xa0±xa02.3xa0hours) or regarding the ovulation rate (70.0% vs. 80.0% vs. 85.0%). However, the maximum diameter of the largest follicle was greater (Pxa0=xa00.06) in the Used2x (15.3xa0±xa00.4xa0mm) than that of New (13.5xa0±xa00.8xa0mm) and Used1x (14.9xa0±xa00.5xa0mm). In experiment 3, 443 anestrous cows were randomly assigned into one of the three treatments (New [nxa0=xa0144] vs. Used1x [nxa0=xa0167] vs. Used2x [nxa0=xa0132]) and received a TAI 48xa0hours after the P4 device removal. The diameter of the largest follicle during the device removal (10.7xa0±xa00.3 vs. 11.2xa0±xa00.2 vs. 11.3xa0±xa00.3xa0mm) and the 30-day pregnancy rates (51.4% vs. 53.9% vs. 43.2%) did not differ among the experimental groups. In experiment 4, a field trial with 593 B indicus (Nelore) cows was conducted to evaluate the pregnancy per AI using different levels of P4 in a TAI protocol (New [nxa0=xa0189] vs. Used1x [nxa0=xa0203] vs. Used2x [nxa0=xa0201]). The pregnancy per AI was similar between the treatment groups (63.5% vs. 57.6% vs. 62.7%). In conclusion, the low circulating P4 concentrations that were released from a used P4 device efficiently controlled the ovarian follicular growth and exhibited no detrimental effects on the pregnancy rates of the B indicus (Nelore) beef cattle.

Ovulation synchronization with estradiol benzoate or GnRH in a timed artificial insemination protocol in buffalo cows and heifers during the nonbreeding season

The aim of this study was to compare estradiol benzoate (EB) and GnRH for the induction of ovulation in a TAI protocol in buffalo during the nonbreeding season. In experiment 1, 141 buffaloes (56 cows and 85 heifers) received an intravaginal P4 device (1.0xa0g) plus EB (2.0-mg, intramuscular [im]) at random stage of the estrous cycle (Day 0). On Day 9, the P4 device was removed, and buffaloes were given PGF2α (0.53-mg im sodium cloprostenol) plus eCG (400-IU im). Buffaloes were then randomly allocated to one of three groups and treated as follows: EB24 (nxa0=xa047), EB (1.0xa0mg im) 24xa0hours after P4 device removal; EB36 (nxa0=xa050), EB 36xa0hours after P4 device removal; GnRH48 (nxa0=xa044), GnRH (10xa0μg im buserelin acetate) 48xa0hours after P4 device removal. Ultrasound examinations were performed on Day 0 to ascertain ovarian follicular status, Day 9 to measure follicular diameter, and from Day 11 to Day 14 (every 12xa0hours for 60xa0hours) to establish the time of ovulation. There were no significant differences between EB24, EB36, and GnRH48 for diameter of the ovulatory follicle (13.1xa0±xa00.3, 13.7xa0±xa00.3, and 13.7xa0±xa00.3xa0mm; Pxa0=xa00.26) and ovulation rate (78.7%, 82.0%, and 84.1%; Pxa0=xa00.93). When compared with heifers, cows had a greater diameter of the dominant follicle on Day 9 (10.3xa0±xa00.3 and 8.6xa0±xa00.2xa0mm; Pxa0=xa00.0001), diameter of the ovulatory follicle (14.1xa0±xa00.3 and 13.1xa0±xa00.2xa0mm; Pxa0=xa00.01), ovulation rate (91.1% and 75.3%; Pxa0=xa00.02), and interval from P4 device removal to ovulation (76.3xa0±xa01.3 and 72.5xa0±xa01.4xa0hours; Pxa0=xa00.05). In experiment 2, 511 buffaloes (354 cows and 157 heifers) were assigned to the same treatments described in experiment 1 (EB24, nxa0=xa0168; EB36, nxa0=xa0172; and GnRH48, nxa0=xa0171), and all animals were submitted to timed artificial insemination (TAI) 64xa0hours after P4 device removal. Pregnancy diagnosis was undertaken 30xa0days after TAI. There were no significant differences between EB24, EB36, and GnRH48 for pregnancy rate (45.2%, 43.0%, and 49.7%; Pxa0=xa00.46), and the pregnancy rate did not differ (Pxa0=xa00.31) for cows (47.5%) and heifers (42.7%). The findings from the two experiments indicated that EB (24 or 36xa0hours) and GnRH (48xa0hours) induce comparable follicular responses, ovulation, and pregnancy rates in buffalo cows and heifers. Although there were some differences in the follicular responses between cows and heifers, the pregnancy rate to TAI was nonetheless similar.

Effect of a new device for sustained progesterone release on the progesterone concentration, ovarian follicular diameter, time of ovulation and pregnancy rate of ewes

This study evaluated the effectiveness of a new progesterone intravaginal device (DPR) in ewes through four experiments: Experiment 1 compared the circulating progesterone concentration of ovariectomized ewes that received either a new or a re-used DPR. Experiment 2 compared the progesterone concentration between DPR-estrous-synchronized ewes and naturally estrous-cycling ewes. Experiment 3 evaluated the effect of new and re-used DPRs on ovarian follicular dynamics and time of ovulation of estrous cycling ewes. Experiment 4 compared the pregnancy rate after the use of a DPR and Controlled Internal Drug Releasing Device (CIDR). The mean concentration of progesterone released by the DPR device during its first use (New Group: 5.1 ± 0.5 ng/ml) was greater than that during the second use (Re-used Group: 2.4 ± 0.3 ng/ml). There was no difference between the animals that received DPR devices for first and second use in terms of ovulatory follicle diameter, follicular wave emergence day for ovulatory follicle and period of ovulatory wave of ovarian follicular development. However, there was a significant difference between groups regarding the time between DPR device removal and first ovulation (New Group: 71.7 ± 2.5h and Re-Used Group: 63.9 ± 2.7h). Pregnancy rates were similar between ewes with DPR and CIDR devices. It was concluded that DPR is effective in increasing and maintaining progesterone concentrations, controlling follicular dynamics, promoting synchronized times of ovulation from healthy follicles, promoting development of a competent corpus luteum and when used results in pregnancy rates similar to that with use of the CIDR.

Comparative efficacy of exogenous eCG and progesterone on endogenous progesterone and pregnancy in Holstein cows submitted to timed artificial insemination

The objectives were to evaluate the effects of the administration of either eCG or progesterone (P4) alone or combined on endogenous P4 concentrations and pregnancy per AI in lactating dairy cows. Cows received a P4-releasing intravaginal device (PRID) and estradiol benzoate on D-8. The PRID was removed and a PGF2α injection was given on D-3. An estradiol cypionate was given on D-2 and TAI was performed on D0. On D-2, cows were randomly allocated to treatments in a 2×2 factorial design: Control-saline solution on the D-2 and D+3 (n=104), eCG - 400IU eCG on D-2 (n=93), P4 - 600mg of P4 on D+3 (n=106), and eCG+P4 - 400IU eCG on D-2 and 600mg of P4 on D+3 (n=95). Blood samples were collected on days three, four, and thirteen and pregnancy diagnoses were performed at 32 and 46 days after AI. There was no interaction between eCG and P4 injection. Cows treated with eCG and with P4 injection had higher serum P4 on Day +4. On Day +13 serum P4 was lower in eCG-untreated primiparous cows (Interaction eCG×parity). Cows with serum P4<4.57ng/mL on Day +13 had lower probability to be pregnant on day 32. P/AI on days 32 and 46 and embryonic losses were not influenced by eCG and P4 injection. In conclusion, the addition of 400IU of eCG on D-2 and/or 600mg of P4 on D+3 to the present TAI protocol did not increase P/AI.

Oxylipidomics of the cow uterus: effects of the peri-ovulatory endocrine milieu of the estrous cycle

Univ Estadual Paulista, Dept Clin Surg & Anim Reprod, Fac Vet Med, UNESP, Sao Paulo, BrazilUNESP, Sch Vet Med & Anim Sci, Dept Anim Reprod, Lab Adv Reprod & Cell Therapy LAN A, Botucatu, SP, Brazil

Progesterone production in superovulated holstein heifers and in crossbred recipient of embryo supplemented with betacarotene and tocopherol

Two experiments were conducted to evaluate the effect of the intramuscular injection of betacarotene associated to tocopherol on the plasma concentration progesterone of superovulated Holstein heifers (experiment 1) and in crossbred (Bos taurus x Bos indicus) heifers submitted to fixed-time embryo transfer (FTET, experiment 2). In experiment 1, after estrus synchronization and superovulation animals were inseminated 12 and 24 hours after estrus onset and embryos flushed 7 days later. Heifers were allocated randomly to one of three treatments: Control; T800 (800 mg of betacarotene plus 500 mg of tocopherol) and T1200 (1,200 mg of betacarotene plus 750 mg of tocopherol). The treatments were given on the day of ear implant placement and repeated on the first day of superovulation. Blood samples were collected on D0, D5, D9, D12 and D16. In experiment 2, treatments were imposed at intravaginal device insertion (D0). The same experimental design, as in experiment 1, was used. Blood samples were collected on D17 (embryos implanted) for progesterone determination by radioimmunoassay. In experiment 1, average plasma progesterone concentrations after corpora lutea formation (D12 plus D16 means) were 13.7±1.8 ng/ml, 14.5±2.3 ng/ml and 10.8±2.3 ng/ml for control, T800 and T1200, respectively, and did not differ (P=0.44). In experiment 2, progesterone concentrations on D17 in Control (8.88±0.57 ng/ml), T800 (7.48±0.64 ng/ml) and T1200 (5.90±1.33 ng/ml) groups were similar (P=0.11). Results indicate that the supplemental betacarotene and tocopherol injections did not influence peripheral progesterone concentrations in superovulated Holstein donors and crossbreed recipients heifers.