Comparison between the 5-day cosynch and 7-day estradiol-based protocols for synchronization of ovulation and timed artificial insemination in suckled BOS taurus BEEF cows

The objective was to compare pregnancy per AI and follicular dynamic in suckled Bos taurus beef cows treated with either a 7-day progesterone + estradiol-based protocol or a 5-day progesterone CoSynch protocol for timed artificial insemination (TAI) during four breeding seasons. We hypothesized that estrous cycle status, days postpartum (DPP), fat depth and plasma progesterone concentration differentially modify the effect of treatments. Every year, 9 days before initiation of each breeding season, cows were randomly assigned to one of two groups. Cows in the 7-d P + E group (n = 428) received a progesterone intravaginal device (DIB) and estradiol benzoate on Day −9. On Day −2 the device was removed, and cows received cloprostenol and estradiol cypionate. Forty-eight hours later (Day 0) cows received TAI. Cows in the 5-d P + CoS group (n = 428) received a DIB, and GnRH on Day −8. On Day −3, the device was removed, and cows received cloprostenol. A second dose of cloprostenol was given on Day −2. Cows received GnRH and TAI 72 h after device removal (Day 0). On Day −9, estrous cycle status was determined. In a subset of cows (n = 79) the size of the dominant follicle was determined between Days −2 and 0. In another subset of cows (n = 340), DPP, fat depth (mm) and plasma progesterone concentration (ng/mL) were evaluated on Day −9. Pregnancy per AI was determined 30 d after TAI. Pregnancy per AI was greater for cows in the 5-d P + CoS group than for cows in the 7-d P + E group (50.9% vs. 41.3%, P = 0.01) and was also greater in cyclic than in anestrus cows (54.3% vs. 33.2%, P < 0.0001). There was also a significant effect of breeding season (P = 0.0002) and sire (P = 0.03), and an interaction between treatment group and breeding season (P = 0.03). The dominant follicle was larger (P < 0.0001) in cows in the 5-d P + CoS group than the 7-d P + E group (10.7 ± 0.29 mm vs. 9.0 ± 0.28 mm). Pregnancy per AI was greater in cows with ≥55 DPP (47.0% vs. 29.6%, P = 0.001), fat depth ≥0.50 mm (44.7% vs. 29.7%), and with plasma progesterone concentration ≥1 ng/mL (47.2% vs. 28.7%, P = 0.01). In cows with plasma progesterone ≥1 ng/mL on Day −9, pregnancy per AI was greater in the 5-d P + CoS group (60.5%) than in the 7-d P + E group (34.9%), but there was no difference between treatment groups in cows with plasma progesterone < 1 ng/mL (P = 0.07). In conclusion, the 5-d P + CoS protocol resulted in greater size of the dominant follicle and pregnancy per AI in suckled Bos taurus beef cows subjected to TAI.Fil: Bilbao, María Guillermina. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Zapata, Luis Oscar. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Romero Harry, H.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; ArgentinaFil: Perez Wallace, S.. Zoetis SRL; ArgentinaFil: Farcey, Maria Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Gelid, Lucas Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; ArgentinaFil: Palomares, R. A.. University of Georgia. College of Veterinary Medicine; Estados UnidosFil: Ferrer, M. S.. University of Georgia. College of Veterinary Medicine; Estados UnidosFil: Bartolome, Julian. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentin

Hormone Concentrations and Semen Parameters in Criollo Breed Stallions Under Training

The stress associated with training may reduce reproductive efficiency in Criollo stallions. The objective of this study was to compare semen quality and hormone concentrations in Criollo stallions under training or under regular field conditions. Criollo breed stallions (n ¼ 18) were evaluated during the spring. The exercise group (n ¼ 9) performed 1 hour of exercise per day and participated in competitions during the experimental period. The control group (n ¼ 9) neither performed exercise nor participated in competitions. Serum and semen samples were obtained every 15 days (two separate ejaculates an hour apart). Sperm motility, velocity, and morphology were evaluated with a phase-contrast microscope and concentration by a hemocytometer. Diff-Quik stain was used to identify polymorphonuclear cells, and the degree of chromatin condensation was evaluated with the toluidine blue stain. The sperm survival test was performed at a room temperature of 22C. Semen evaluation was performed in raw samples and in samples diluted in a skim milk and glucose-based extender. Cortisol, testosterone, and estradiol were measured using radioimmunoassay. There was no effect of exercise on testosterone and estradiol concentrations (P ¼ .28 and P ¼ .97, respectively). However, in the exercise group, cortisol concentration was higher after exercise (P ¼ .004). There was an effect of exercise on the following semen parameters: gelfree volume (P < .001), sperm motility (P < .0001), total number of sperm (P ¼ .0001), normal sperm morphology (P < .0001), and total number of morphologically normal and motile sperm (P < .001). No effect of exercise was found in the following semen parameters: color, pH, and sperm concentration. This study showed that exercise had a negative impact on seminal quality; nevertheless, semen parameters were within the normal ranges established for the equine species.Fil: Rosseto, Liliana. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias. Departamento de Producción Animal. Cátedra de Reproducción Animal; ArgentinaFil: Farcey, Maria Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias. Departamento de Producción Animal. Cátedra de Reproducción Animal; ArgentinaFil: Bilbao, María Guillermina. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias. Departamento de Producción Animal. Cátedra de Reproducción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Bartolome, Julian. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias. Departamento de Producción Animal. Cátedra de Reproducción Animal; ArgentinaFil: Gallelli, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Instituto de Investigación y Tecnología en Reproducción Animal; ArgentinaFil: Miragaya, Marcelo. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Instituto de Investigación y Tecnología en Reproducción Animal; Argentin

Hormonal levels and semen parameters of Criollo breed stallions under intensive training

The stress associated with intensive training may reduce reproductive efficiency in Criollo stallions. The objective was to compare semen quality and cortisol, testosterone, and estradiol levels in Criollo stallions under training conditions with those of stallions under regular field conditions. Criollo breed stallions (n¼18) were evaluated from August 15th to October 30th. The Exercise group (ExG, n¼9) received one hour of exercise per day, and participated in competitions during the experimental period. The Control group (CoG, n¼9) neither exercise nor participated in competition. Before the initiation of the experiment, semen was collected by artificial vagina twice a day for 7 consecutive days to keep the stallions in daily sperm output (DSO). Every 15 days semen (2 separate ejaculates an hour apart) and serum samples (before and after exercise in ExG) were collected. Analysis of variance using repeated measures (SAS System) with stallions nested in treatments and day as repeated factor was used to evaluate the results. There was no effect of exercise in testosterone levels (pre-exercise: 0.58 0.06 ng/mL, post-exercise: 0.66 0.06 ng/mL, CoG: 0.50 0.06 ng/mL; P¼ 0.28) and estradiol levels (pre-exercise: 222.17 36.23 pg/mL, post-exercise: 228.84 36.23 pg/mL, CoG ¼ 231.91 36.08 pg/mL; P¼0.97). However, in the ExG cortisol level was higher after exercise (pre-exercise 59.96 4.58 nM/mL vs. posexercise 81.05 4.58 nM/mL) while in the CoG cortisol level was 59.80 4.57 nM/mL (P¼0.004). There was an effect of exercise on the following semen parameters: gel-free volume (ExG 41.46 6.1 ml vs. CoG 53.33 6.3 ml; P<0.001), sperm motility (ExG 47.8 2.53 % vs. CoG 63.56 2.5 %; P <0.0001), total number of sperm (ExG 8104.91 1267.16 x 106 vs. CoG 12124.16 1252.58 x 106 ; P¼ 0,0001), normal sperm morphology (ExG 60.03% 1,69 vs CoG 76.73% 1.67; P < 0.0001) and total number of morphologically normal and motile sperm (ExG 2277.65 564.2 x 106 vs. CoG 5730.54 557.3 x 106 ; P<0.001). No effect of exercise was found in color, pH, sperm concentration. The study showed that exercise under this experimental condition had a negative impact on seminal quality. Nevertheless, semen parameters remained within the normal ranges established for stallions.Fil: Rossetto, Liliana. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Farcey, Maria Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Chapero, Luisina Andrea. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Bilbao, María Guillermina. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Bartolome, Julian. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Miragaya, Marcelo. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Instituto de Investigación y Tecnología en Reproducción Animal; Argentin

Extending the duration of treatment with progesterone and equine chorionic gonadotropin improves fertility in suckled beef cows with low body condition score subjected to timed artificial insemination

The objective of this study was to evaluate the effect of an extended progesterone treatment on follicular development and fertility in postpartum, suckled beef cows subjected to timed artificial insemination (TAI). In experiment 1, cows (n = 24) with body condition score (BCS) ≥4.5 received either a 2-g progesterone intravaginal device on Day −23 or a 0.558-g progesterone intravaginal device on Day −9. Then, all cows received 2 mg of estradiol benzoate on Day −9; removal of the device, 1-mg estradiol cypionate, and PGF2α on Day −2; and TAI on Day 0. Metabolic status was assessed between Days −9 and −2. Ovarian structures and plasma progesterone were determined weekly from Day −23 to −9, daily from Day −9 to 0, and weekly until Day 28. In experiment 2, cows (n = 302) with BCS ≥4.5 received identical treatment to cows in experiment 1, but on Day −2, cows received 400 IU of two different commercial preparations of equine chorionic gonadotropin (eCG). Ovarian structures were determined on Days −23 and −9 on a subset of cows (n = 40). Pregnancy was determined 39 days after TAI. In experiment 3, multiparous cows (n = 244) with BCS <5.0 received identical treatment as cows in experiment 1 initiated on Day −18, and on Day −2, cows received 400 IU of eCG or no treatment. Ovarian structures were determined in a subset of cows (n = 31) on Days −3, −2, −1, 0, 1, and on Day 10. Pregnancy was determined 39 days after TAI. The results indicated that in experiment 1, plasma progesterone was higher in treated than nontreated (control cows) during the first 14 days (P = 0.0001). The extended progesterone treatment increased the size of the largest follicle between Days −23 and Day −5 (Group by Day, P = 0.04) and tended to increase the size of the dominant follicle from Day −5 to Day −1 (Group by Day, P = 0.06). There was no effect of metabolic status or interaction between metabolic status and day on follicular growth. In experiment 2, extended progesterone treatment tended to increase the size of the largest follicle between Day −23 and −9 (P = 0.06). There was no effect of Group, eCG, BCS, and parity on pregnancy per AI. In experiment 3, extended progesterone treatment combined with eCG increased the size of the dominant follicle (P = 0.01). Both extended progesterone treatment (P = 0.02) and eCG (P = 0.03) increased pregnancy per AI. In conclusion, an extended progesterone treatment stimulated follicular growth postpartum and improved fertility only in cows with low BCS.Fil: Bilbao, María Guillermina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Massara, N.. No especifíca;Fil: Ramos, S.. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Zapata, Luis Oscar. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Farcey, Maria Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Pesoa, J.. Biogénesis Bagó S. A.; ArgentinaFil: Turic, E.. Biogénesis Bagó S. A.; ArgentinaFil: Vázquez, M. I.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Bartolome, J. A.. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentin