RESUMEN
The time at which follicles acquire LHR in bovine granulosa cells is the subject of some controversy among researchers. The main objective of the present study was to assess the mRNA expression of LHR and LRBP (mRNA protein binding), a post-transcriptional suppressor of LHR mRNA expression, in granulosa cells from the two largest follicles around the expected time of follicle deviation in Nelore heifers. First, the interval between ovulation and follicle deviation in 20 Nelore heifers was determined (2.3 ± 0.2 days after ovulation). Ovulation was hormonally synchronized, and then, heifers were slaughtered on days 2, 2.5 and 3 after ovulation (before, during and after, respectively, the expected time of follicle deviation), and granulosa cells from the two largest follicles were collected. The mRNA abundance of an LHR fragment common to all isoforms (total LHR) and LRBP was assessed by real-time RT-PCR, and LHR alternative transcripts were assessed by semiquantitative RT-PCR followed by electrophoresis. LHR mRNA expression was not detected before the expected time of deviation. Total LHR mRNA abundance was greater in the largest follicle and increased from day 2.5 to 3. In contrast, LRBP mRNA was detected starting on day 2 and was more expressed in the second largest follicle on days 2.5 and 3. The present data suggest that the expression of LHR mRNA in bovine granulosa cells is established after follicle deviation and that the lower abundance of LRBP mRNA after the expected time of deviation may contribute to greater expression of LHR in the bovine dominant follicle.
Asunto(s)
Bovinos/genética , Células de la Granulosa/metabolismo , Folículo Ovárico/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Receptores de HL/genética , Animales , Femenino , Expresión Génica , Ovulación/genética , ARN Mensajero/genética , Transducción de Señal/genéticaRESUMEN
The IGF system is related to embryo quality. We aim to determine the effect of the heat stress on the mRNA expression of IGF1 and IGF2, IGFR1 and IGFR2, IGFBP2 and IGFBP4, and PAPPA in in vitro production (IVP) blastocysts from Nelore and Holstein after ovum pick up (OPU) to better understand the differences between these breeds. Oocytes from four Nelore and seven Holstein were collected in six OPU sessions. Following in vitro maturation and fertilization using six Nelore or Holstein sires, embryos were divided into control (cultured at 39°C) and heat stress (HS; exposed to 41°C for 9 h). Blastocysts were submitted to RNA extraction. The IGF1 expression was higher in blastocysts under HS in both breeds, and the expression of IGFBP2 and IGFBP4 was higher in Holstein blastocysts under HS. The high PAPPA expression and the low expression of IGFBP2 and IGFBP4 are associated with a more efficient degradation of IGFBPs, which results in greater IGF bioavailability in Nelore blastocysts and may contribute to the superior HS tolerance in Nelore, when compared to Holstein.
Asunto(s)
Bovinos/genética , Bovinos/fisiología , Técnicas de Cultivo de Embriones/veterinaria , Calor , Somatomedinas/metabolismo , Animales , Femenino , Fertilización In Vitro/veterinaria , Regulación del Desarrollo de la Expresión Génica/fisiología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Somatomedinas/genética , Especificidad de la Especie , Estrés Fisiológico/fisiología , TranscriptomaRESUMEN
The objective was to evaluate the effects of plasma progesterone (P4) concentrations and exogenous eCG on ovulation and pregnancy rates of pubertal Nellore heifers in fixed-time artificial insemination (FTAI) protocols. In Experiment 1 (Exp. 1), on Day 0 (7 d after ovulation), heifers (n = 15) were given 2 mg of estradiol benzoate (EB) im and randomly allocated to receive: an intravaginal progesterone-releasing device containing 0.558 g of P4 (group 0.5G, n = 4); an intravaginal device containing 1 g of P4 (group 1G, n = 4); 0.558 g of P4 and PGF(2α) (PGF; 150 µg d-cloprostenol, group 0.5G/PGF, n = 4); or 1 g of P4 and PGF (group 1G/PGF, n = 3). On Day 8, PGF was given to all heifers and intravaginal devices removed; 24 h later (Day 9), all heifers were given 1 mg EB im. In Exp. 2, pubertal Nellore heifers (n = 292) were treated as in Exp. 1, with FTAI on Day 10 (30 to 36 h after EB). In Exp. 3, pubertal heifers (n = 459) received the treatments described for groups 0.5G/PGF and 1G/PGF and were also given 300 IU of eCG im (groups 0.5G/PGF/eCG and 1G/PGF/eCG) at device removal (Day 8). In Exp. 1, plasma P4 concentrations were significantly higher in heifers that received 1.0 vs 0.588 g P4, and were significantly lower in heifers that received PGF on Day 0. In Exp. 2 and 3, there were no significant differences among groups in rates of ovulation (65-77%) or pregnancy (Exp. 2: 26-33%; Exp. 3: 39-43%). In Exp. 3, diameter of the dominant ovarian follicle on Day 9 was larger in heifers given 0.558 g vs 1.0 g P4 (10.3 ± 0.2 vs 9.3 ± 0.2 mm; P < 0.01). In conclusion, lesser amounts of P4 in the intravaginal device or PGF on Day 0 decreased plasma P4 from Days 1 to 8 and increased diameter of the dominant follicle on Day 9. However, neither of these nor 300 IU of eCG on Day 8 significantly increased rates of ovulation or pregnancy.
Asunto(s)
Bovinos/fisiología , Gonadotropina Coriónica/farmacología , Ovulación/fisiología , Progesterona/sangre , Animales , Estradiol/análogos & derivados , Estradiol/farmacología , Femenino , Inseminación Artificial/métodos , Inseminación Artificial/veterinaria , Ovulación/efectos de los fármacos , Inducción de la Ovulación , Embarazo , Índice de Embarazo , Progesterona/farmacología , Prostaglandinas F/farmacologíaRESUMEN
The objective was to evaluate the effects of temporary calf removal (TCR), eCG administration, or both, in a progesterone-based protocol. Suckled Nellore cows (40-80 d postpartum, n=443) with body condition scores from 2.0 to 3.5 (5-point scale) on three farms were all given a synchronizing protocol (PEPE). At the start (designated Day 0), cows were given an intravaginal device (1.0 g of progesterone) and 2.5mg of estradiol benzoate (EB) im. On Day 8, the device was removed and cows were given PGF(2 alpha) (150 microg of D-cloprostenol im), followed in 24h by 1.0mg EB im, and 30-36 h thereafter, fixed-time AI. The design was a 2 x 2 factorial; main effects were TCR (54-60 h; from device removal to FTAI) and eCG treatment (300 IU im, concurrent with PGF(2 alpha)). Transrectal ultrasonography was done on Days -10 and 0 to detect anestrus (absence of a CL at both examinations) and approximately 30 d after FTAI (pregnancy diagnosis). Data were analyzed by logistic regression. The following variables did not significantly affect pregnancy rates: farm, postpartum interval, cyclicity, inseminators, and semen (sire). Overall, 77% of the cows were deemed anestrus. Pregnancy rates were similar (P>0.05) among treatment groups: Control (54/108=50.0%), TCR (44/106=41.5%), eCG (63/116=54.3%), and TCR+eCG (49/113=43.4%). Pregnancy rate was higher in multiparous than primiparous cows (186/360, 51.7% vs. 24/83, 28.9%, P<0.01), but was not significantly affected by cyclicity status or body condition score. In conclusion, temporary calf removal, eCG, or both, did not significantly increase pregnancy rate to timed-insemination in a progesterone-based synchronization protocol in postpartum Nellore cows with acceptable body condition.
Asunto(s)
Bovinos , Gonadotropina Coriónica/farmacología , Inseminación Artificial/veterinaria , Lactancia/fisiología , Progesterona/farmacología , Administración Intravaginal , Animales , Animales Lactantes , Dinoprost/farmacología , Estradiol/administración & dosificación , Estradiol/análogos & derivados , Estradiol/farmacología , Sincronización del Estro/efectos de los fármacos , Femenino , Fármacos para la Fertilidad Femenina/administración & dosificación , Fármacos para la Fertilidad Femenina/farmacología , Periodo Posparto , Embarazo , Progesterona/administración & dosificaciónRESUMEN
Analisaram-se 140 amostras de soro sangüíneo de bezerros da raça Holandesa, recém nascidos, com o objetivo de verificar a relaçäo entre a concentraçäo de gamaglobulina e as atividades das enzimas gamaglutamiltransferase, fosfatase alcalina e aspartato aminotransferase nos primeiros seis dias de vida. Näo se observou correlaçäo significativa entre os níveis de gamaglobulina e atividade de aspartato aminotransferase. A correlaçäo positiva significativa verificada no primeiro dia de vida, entre teor de globulina e atividade da fosfatase alcalina foi de pouca intensidade, näo sendo considerado um teste seguro de identificaçäo de hipogamaglobulinemia. Observou-se correlaçäo positiva significativa, com variaçöes intensas, ao redor de 24 a 30 horas pós-nascimento, entre níveis de gamaglobulina e atividade da gamaglutamiltransferase, quando comparados aos valores obtidos nas primeiras seis horas pós-natal. Pode-se considerar tal enzima como teste de identificaçäo indireta de bezerros hipogamaglobulinêmicos, por falha na transferência de imunoglobulinas colostrais