RESUMEN
The antral follicle count (AFC) in cattle is consistent throughout the estrous cycle of individual cows, and cows with a lower AFC have lower fertility. We assessed the AFC at random stages of the estrous cycle, examined the correlation between AFC classifications, and determined the relationship between the most rapid and practical laboratory-based AFC classification (AFC of follicles of ≥ 2 mm in diameter) and fertility measures in New Zealand lactating dairy cows. Cows detected in estrus (n = 202) or not (n = 239) during the first 4 weeks of the breeding season were subjected to ultrasonography and classified as having a high, medium, or low AFC at the time of scanning (on-site classification). Images from ultrasound scanning were recorded onto video for accurate follicle counting in an imaging laboratory. A strong association (P < 0.05) between the AFC of follicles with a diameter of 2 mm or greater and fertility was observed. Cows with a high AFC had a shorter (P < 0.05) interval from calving to conception by artificial insemination (AI; 82.4 ± 1.6 vs. 87.3 ± 1.2 days) and greater pregnancy rates (PRs; i.e., PR to the first AI [68.1% vs. 45.3%], 6-week PR [81.9% vs. 67.3%], and overall PR [91.3% vs. 79.7%]) than cows with a low AFC. The AFC was positively associated (P < 0.0001) with age. Progesterone concentrations during diestrus were greater (P < 0.05) in high-AFC cows (7.6 ± 0.3 ng/mL) than in low-AFC cows (6.5 ± 0.3 ng/mL), whether these were pregnant (7.7 ± 0.3 ng/mL) or not (6.3 ± 0.2 ng/mL). A rapid on-site scoring system determined that cows classified as having a high AFC had a shorter (P < 0.05) interval from calving to the first AI (76.5 ± 1.7 vs. 82.3 ± 1.9 days) and were more likely to show estrus (P < 0.01; 56.8% vs. 36.4%) and have a CL at the beginning of the breeding season (P < 0.01; 93.4% vs. 79.6%) than cows with a low on-site AFC. Collectively, we have confirmed an association between AFC2 and fertility, and these results support the hypothesis that cows with a greater number of antral follicles are more fertile than cows with a lesser number of follicles. Although the on-site classification was related to resumption of estrous cycles after calving, associations with other fertility measurements could not be observed, highlighting a need for further refinement of the on-site classification system for rapid phenotyping of the AFC.
Asunto(s)
Bovinos/fisiología , Industria Lechera/métodos , Fertilidad/fisiología , Lactancia , Folículo Ovárico/anatomía & histología , Reproducción , Animales , Cruzamiento , Femenino , Fertilización/fisiología , Humanos , Inseminación Artificial , Nueva Zelanda , Folículo Ovárico/diagnóstico por imagen , Embarazo , Índice de Embarazo , Progesterona/sangre , Factores de Tiempo , UltrasonografíaRESUMEN
Hyaluronan (HA) is glycosaminoglycan that is present from the start of embryonic development and its role and concentration increases with embryo development. The objective of this study was to evaluate if the presence of HA in TCM-199 culture medium had an effect on the development and quality of bovine embryos. There was no effect of HA on the total number of zygotes developing to blastocysts on day 7, however more expanded and hatched blastocyst stages were observed on days 8 and 9 in the group supplemented with HA (p<0.05). Following freeze/thawing, significantly more (p<0.05) embryos cultured in medium supplemented with HA hatched than those cultured in TCM-199 alone or those with BSA. Medium supplemented with HA and BSA significantly increased the level of expression of glucose metabolism Glut-1 gene and embryo compaction Cx43 gene (p<0.05), and had no effect on Glut-5 and IGF-II expression. In addition, HA presence in culture decreased the level of expression of apoptosis Bax and oxidative stress SOX genes (p<0.05). There was significant difference in total number of nuclei between TCM-199 medium only and the remaining media containing BSA or HA plus BSA, between which there was no difference. In summary, our results indicate that the addition of high molecular weight HA to TCM-199 medium that contains BSA on day 4 of culture improved embryo development to hatching and hatched blastocysts and the quality of produced embryos, which were superior to embryos cultured without HA addition.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Medios de Cultivo , Técnicas de Cultivo de Embriones , Embrión de Mamíferos/efectos de los fármacos , Embrión de Mamíferos/metabolismo , Desarrollo Embrionario/efectos de los fármacos , Ácido Hialurónico/farmacología , Animales , Blastocisto/citología , Blastocisto/metabolismo , Bovinos , Fertilización In Vitro , Congelación , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given 100 microg of GnRH im were determined in three experiments. In Experiment 1, heifers were given GnRH 3, 6 or 9 days after ovulation; 8/9, 5/9 and 2/9 ovulated (P<0.02). Mean plasma concentrations of progesterone were lowest (P<0.01) and of LH were highest (P<0.03) in heifers treated 3 days after ovulation. In Experiment 2, heifers received no treatment (Control) or one or two previously used CIDR inserts (Low-P4 and High-P4 groups, respectively) on Day 4 (estrus=Day 0). On Day 5, the Low-P4 group received prostaglandin F(2alpha) (PGF) twice, 12 h apart and on Day 6, all heifers received GnRH. Compared to heifers in the Control and Low-P4 groups, heifers in the High-P4 group had higher (P<0.01) plasma progesterone concentrations on Day 6 (3.0+/-0.3, 3.0+/-0.3 and 5.7+/-0.4 ng/ml, respectively; mean+/-S.E.M.) and a lower (P<0.01) incidence of GnRH-induced ovulation (10/10, 9/10 and 3/10). In Experiment 3, 4-6 days after ovulation, 20 beef heifers and 20 suckled beef cows were given a once-used CIDR, the two largest follicles were ablated, and the cattle were allocated to receive either PGF (repeated 12h later) or no additional treatment (Low-P4 and High-P4, respectively). All cattle received GnRH 6-8 days after follicular ablation. There was no difference between heifers and cows for ovulatory response (77.7 and 78.9%, P<0.9) or the GnRH-induced LH surge (P<0.3). However, the Low-P4 group had a higher (P<0.01) ovulatory response (94.7% versus 61.1%) and a greater LH surge of longer duration (P<0.001). In conclusion, although high plasma progesterone concentrations reduced both GnRH-induced increases in plasma LH concentrations and ovulatory responses in beef cattle, the hypothesis that heifers were more sensitive than cows to the suppressive effects of progesterone was not supported.
Asunto(s)
Bovinos/fisiología , Hormona Liberadora de Gonadotropina/farmacología , Hormona Luteinizante/metabolismo , Folículo Ovárico/fisiología , Inducción de la Ovulación/veterinaria , Progesterona/sangre , Animales , Área Bajo la Curva , Bovinos/sangre , Femenino , Hormona Luteinizante/sangre , Folículo Ovárico/diagnóstico por imagen , Folículo Ovárico/efectos de los fármacos , Inducción de la Ovulación/métodos , UltrasonografíaRESUMEN
Two experiments were designed to determine the efficacy of intraglandular antibiotic treatment in beef bulls. Experiment 1 was designed to evaluate the glandular tissue reaction to intraglandular antibiotic treatment. Experiment 2 was conducted to determine the efficacy intraglandular injection of antibiotics for the treatment of naturally occurring cases of vesicular adenitis. Healthy beef bulls (n=15), 2 and 3 years of age, were randomly allocated to three equal treatment groups to receive 10% of the daily recommended parenteral dose of penicillin, ceftiofur, or oxytetracycline in a volume of 6 mL injected directly into one of the vesicular glands. Ultrasonography was performed before, immediately after, and at 24, 48 and 168 h after intraglandular injection. The size and hardness of vesicular glands injected with oxytetracycline was greater (P<0.01) than those injected with ceftiofur. Ultrasonographic pixel intensity increased (P<0.01) after treatment with antibiotics, especially after treatment with oxytetracycline or penicillin. In Experiment 2, yearling beef bulls with clinical vesicular adenitis (n=14) were referred to the Western College of Veterinary Medicine for treatment. Eight bulls had unilateral and six had bilateral vesicular adenitis. The most common isolate was Arcanobacterium pyogenes. Corynebacterium pseudotuberculosis was isolated from one bull. Bulls were subjected to rectal palpation and ultrasonography of the vesicular glands, semen collection by electroejaculation, and intraglandular treatment with ceftiofur (n=13) and if necessary, a second intraglandular treatment of penicillin (n=6). One bull was treated only with an initial intraglandular injection of penicillin. Bulls were evaluated once a week over 6 weeks by palpation of the glands, and evaluation of semen. All bulls recovered from vesicular adenitis after 3-6 weeks. There was a difference in the amount of pus (P=0.042), leukocytes (P<0.001) and blood (P=0.003) present in ejaculates from before treatment to 3 weeks after treatment. Pixel intensities in ultrasonographic images of healthy or affected vesicular glands, whether treated or untreated, did not change over time. Intraglandular injection of ceftiofur in yearling bulls via the ischiorectal fossa was effective for treating vesicular adenitis.
Asunto(s)
Sacos Anales/microbiología , Antibacterianos/administración & dosificación , Infecciones Bacterianas/veterinaria , Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/microbiología , Linfadenitis/tratamiento farmacológico , Linfadenitis/veterinaria , Administración Rectal , Sacos Anales/diagnóstico por imagen , Sacos Anales/efectos de los fármacos , Animales , Infecciones Bacterianas/diagnóstico por imagen , Infecciones Bacterianas/tratamiento farmacológico , Infecciones Bacterianas/microbiología , Bovinos , Enfermedades de los Bovinos/diagnóstico por imagen , Cefalosporinas/administración & dosificación , Linfadenitis/diagnóstico por imagen , Linfadenitis/microbiología , Masculino , Oxitetraciclina/administración & dosificación , Penicilina G/administración & dosificación , Semen/microbiología , Estadísticas no Paramétricas , UltrasonografíaRESUMEN
The objective of this study was to determine whether early detection and treatment with tilmicosin would reduce the number of yearling bulls culled due to vesicular gland disease at the time of their first semen test. Bulls (n=2207) of 15 breeds at 17 performance test stations were examined by transrectal palpation at 9-12 months of age and assigned to three treatment groups: (1) positive treated group, receiving subcutaneous injections of tilmicosin every second day for three treatments (2) positive untreated control group, (3) negative untreated control group. Transrectal palpation of the glands was done again at a pre-sale semen test 28-70 d (mean=42.8 d) after the first examination. Semen was evaluated for the presence of pus and/or leukocytes by light microscopy. The proportion of bulls with vesiculitis was 4.4% (97/2207). At the pre-sale semen test the number of bulls with vesiculitis had decreased to 1.3% (29/2207); however, seven of these were new cases that developed after the first examination. Therefore, there was a recovery rate of 75/97 (77.3%) in the original group of bulls positive for vesiculitis. At the pre-sale test, there was no difference in the proportion of bulls with enlarged glands in the positive treated group (15/66) versus the positive untreated group (7/31) and no difference in the proportion of bulls with leukocytes or pus in their semen samples. The results of this experiment did not indicate any advantage in detection and treatment of vesiculitis before a year on age due to a high rate of spontaneous recovery.
Asunto(s)
Antibacterianos/uso terapéutico , Enfermedades de los Bovinos/diagnóstico , Enfermedades de los Bovinos/tratamiento farmacológico , Linfadenitis/veterinaria , Macrólidos/uso terapéutico , Tilosina/análogos & derivados , Animales , Bovinos , Linfadenitis/diagnóstico , Linfadenitis/tratamiento farmacológico , Masculino , Tilosina/uso terapéuticoRESUMEN
Three experiments were conducted to investigate the ischiorectal fossa (IRF) as a route for the administration of prostaglandin F2 alpha (dinoprost) in cattle. In Experiment 1, 21 nonlactating Holstein cows were given 100 micrograms of gonadotropin releasing hormone (GnRH), intramuscularly (i.m.), and, 7 d later, 25 mg of dinoprost into the IRF. Sixteen cows had serum progesterone concentrations > or = 1.0 ng/mL at the time of dinoprost treatment, and all of these had rapid and complete luteolysis; the other 5 cows were not considered to have a functional corpus luteum (CL) at the time of treatment. There were minimal adverse behavioral reactions to the IRF injections and no visible or palpable tissue reactions at the injection site. In Experiment 2, 74 Holstein heifers were given 25 mg of dinoprost by IRF injection. Luteolysis occurred in 84.3% of the heifers with a functional CL (as determined by the serum progesterone concentration at the time of treatment). Of the heifers bred by either natural service or artificial insemination, 61.8% became pregnant. In Experiment 3, 48 beef heifers received dinoprost 7 d after ovulation, as follows: 25 mg, i.m. (n = 9); 25 mg, IRF (n = 10); 10 mg, IRF (n = 10); 10 mg, subcutaneously (s.c.) (n = 10); or 10 mg, intravulvosubmucosally (IVSM) (n = 9). Fewer heifers (P < 0.05) were found to be in estrus or ovulating in the 10 mg IVSM group (0% and 11%, respectively) than in the 25 mg i.m. group (100% and 100%), the 25 mg IRF group (90% and 100%, respectively), or the 10 mg IRF group (80% and 80%). The rates of estrus (50%) and ovulation (50%) were intermediate in the 10 mg s.c. group. In summary, 25 mg of dinoprost injected into the IRF caused minimal behavioral or tissue response and induced luteolysis and fertile estrus. In addition, 10 mg of dinoprost injected into the IRF was as efficacious as 25 mg given either i.m. or into the IRF in inducing estrus and ovulation.
Asunto(s)
Bovinos/fisiología , Cuerpo Lúteo/efectos de los fármacos , Dinoprost/administración & dosificación , Vías de Administración de Medicamentos/veterinaria , Estro/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Femenino , Hormona Liberadora de Gonadotropina/administración & dosificación , Hormona Liberadora de Gonadotropina/farmacología , Inyecciones Intramusculares/veterinaria , Inseminación Artificial/veterinaria , Inducción de la Ovulación/métodos , Inducción de la Ovulación/veterinaria , Embarazo , Índice de Embarazo , Progesterona/sangre , Distribución Aleatoria , Resultado del TratamientoRESUMEN
Four experiments were conducted to investigate modifications to gonadotropin releasing hormone (GnRH)-based fixed-time Al protocols in beef cattle. In Experiment 1, the effect of reducing the interval from GnRH treatment to prostaglandin (PGF) was examined. Lactating beef cows (n = 111) were given 100 mg gonadorelin (GnRH) on Day 0 (start of treatment) and either 500 microg cloprostenol (PGF) on Day 6 with Al and 100 microg GnRH 60 h later, or PGF on Day 7 with Al and GnRH 48 h later (6- or 7-day Co-Synch regimens). Pregnancy rates were 32/61 (53.3%) versus 26/50 (52.0%), respectively (P = 0.96). In Experiment 2. cattle (n = 196) were synchronized with a 7-day Co-Synch regimen and received either no further treatment or a CIDR-B device (Days 0-7). Pregnancy rates were 32/71 (45.1%) versus 33/77 (42.9%) in cows (P < 0.8), and 9/23 (39.1 %) versus 17/25 (68.0%) in heifers (P < 0.05). In Experiment 3, 49 beef heifers were randomly assigned to receive 12.5 mg pLH on Day 0, PGF on Day 7 and 12.5 mg of pLH on Day 9 with Al 12 h later (pLH Ovsynch), or similar treatment plus a CIDR-B device from Days 0 to 7 (pLH Ovsynch + CIDR-B), or 1 mg estradiol benzoate (EB) and 100 mg progesterone on Day 0, a CIDR-B device from Days 0 to 7 (EB/ P4 + CIDR-B), PGF on Day 7 (at the time of CIDR-B removal) and 1 mg i.m. EB on Day 8 with AI on Day 9 (52 h after PGF). Pregnancy rate in the EB/P4 + CIDR-B group (75.0%) was higher (P < 0.04) than in the pLH Ovsynch group (37.5%): the pLH Ovsynch + CIDR-B group was intermediate (64.7%). In Experiment 4, 266 non-lactating cows were allocated to a 7-day Co-Synch protocol (Co-Synch), a 7-day Co-Synch plus 0.6 mg per head per day melengestrol acetate (MGA) from Days 0 to 6 inclusive (Co-Synch + MGA) or MGA (Days 0-6) plus 2 mg EB and 50 mg progesterone on Day 0. 500 microg PGF on Day 7, 1 mg EB on Day 8 and fixed-time Al 28 h later (EB/ P4 + MGA). Pregnancy rates (P < 0.25) were 44.8% (39/87: Co-Synch), 47.8% (43/90; Co-Synch + MGA), and 60.7% (54/89: EB/P4 + MGA). In conclusion, a 6- or 7-day interval from GnRH to PGF in a Co-Synch regimen resulted in similar pregnancy rates in cows. The addition of a progestin to a Co-Synch or Ovsynch regimen significantly improved pregnancy rates in heifers but not in cows. Progestin-based regimens that included EB consistently resulted in high pregnancy rates to fixed-time Al.