ABSTRACT Global advances in reproductive biotechnology have allowed for the transfer of embryos from donor females with high genetic merit to recipients using the cryopreservation technique, which preserves an embryo of excellent quality and viability, thereby achieving a feasible pregnancy rate. The objective of this study was to evaluate the quality and viability of Holstein embryos that have been cryopreserved for more than 40 years under glycerol freezing. The embryos were transferred to the recipient heifers using a non-surgical method. Two 17-month-old Holstein heifers (360 kg live weights) which were clinically healthy and reproductively active were used as the recipients. Two bovine embryos of Grade 1 quality were thawed and evaluated for their morphology. Of the two embryo transfers, one pregnancy was achieved, resulting in the birth of a calf. Therefore, embryos frozen in liquid nitrogen and glycerol as a cryopreservative for more than 40 years maintained their quality and viability to produce a live calf.

RESUMO Os avanços globais em biotecnologia reprodutiva permitiram a transferência de embriões de fêmeas doadoras com alto mérito genético para receptoras, usando-se a técnica de criopreservação, que preserva um embrião de excelente qualidade e viabilidade, alcançando, assim, uma taxa de gravidez viável. O objetivo deste estudo foi avaliar a qualidade e a viabilidade de embriões Holstein, criopreservados por mais de 40 anos, sob congelamento de glicerol. Os embriões foram transferidos para as novilhas receptoras, usando-se um método não cirúrgico. Duas novilhas Holstein de 17 meses de idade (360kg de peso vivo), que eram clinicamente saudáveis e reprodutivamente ativas, foram utilizadas como receptoras. Dois embriões bovinos de qualidade Grau 1 foram descongelados e avaliados quanto à sua morfologia. Das duas transferências embrionárias, uma gravidez foi obtida, resultando no nascimento de um bezerro. Portanto, os embriões congelados em nitrogênio líquido e glicerol como criopreservante por mais de 40 anos mantiveram sua qualidade e viabilidade para produzir um bezerro vivo.

ABSTRACT The objective of this study was to evaluate the effect of the seasons (Summer and Autumn), on live weight, body condition, mass motility, percentage of live spermatozoa, and sperm-cell concentration of Creole roosters (Gallus domesticus) from Mexico. Semen from 35-week-old Creole roosters was collected weekly during 10 weeks in Summer and Autumn, through the dorso-abdominal massage technique. Roosters were individually kept under a constant photoperiod (16 hours light:8 hours dark). The average live weight was 4.5% higher (p<0.05) in Autumn (2.78 kg) than in Summer (2.66 kg), therefore this variable increased with age (r = 0.85, p<0.05). Category 2 of body condition occurred (p<0.05) with higher probability than the others (0, 1 and 3), being practically the same (p>0.05) in Autumn (99.96%) and in Summer (99.81%). On average (and in weeks 1 and 3-10), the percentage of live spermatozoa was higher in Summer than in Autumn. Accordingly, the percentage of live spermatozoa decreased with age (r = -0.82, p<0.05). However, on average, sperm-cell concentration did not change between seasons (p>0.05). In conclusion, Mexican Creole roosters showed higher percentage of live spermatozoa in Summer than in Autumn. Therefore, it is advisable to select these animals of about 2.7 kg and reproduce them in Summer.

The aim of this study was to evaluate ovarian follicular activity, ovulation percentage, and body weight change in response to focused nutrition during synchronization of oestrus with an intravaginal device (CIDR®) (9 days) in Pelibuey ewes with high and low body condition. Seventy-two non-pregnant ewes without offspring were randomly distributed to one of four treatments, namely T1: (n = 18) ewes without focused nutrition and low body condition; T2: (n = 18) ewes without focused nutrition and high body condition; T3: (n = 18) ewes with focused nutrition and low body condition; and T4: (n = 18) ewes with focused nutrition and high body condition. While the CIDR device was in place, the ewes with focused nutrition received a supplement of 1.5 kg ewe/day, which contained 2.9 MCal metabolizable energy, 16% crude protein, 88.5% dry matter, 11.8% crude fibre, and 6.7% of ash. The concentration of progesterone (P4) was measured to determine ovulation percentage. The follicular population was quantified (2-3 mm, 4-5 mm, and >6 mm in diameter). The number of follicles between 2-3 mm and 4-5 mm in diameter was similar among treatments. The number of follicles >6 mm in diameter was higher in T4 ewes (2.2 ± 0.2) compared with T1, T2, and T3. The response to oestrus, the onset of oestrus, and the ovulation percentage were similar among treatments. Focused nutrition increased the number of ovarian follicles >6 mm in diameter in ewes with high body condition.

Post-partum anestrus is a problem on farms, and its duration depends on the frequency and intensity of suckling which affects reproduction and production efficiency to become a determining economic factor. The aim of this study was to determine the post-partum reproductive response in ewe to a "male effect" with an ovulation induction protocol of five days using progesterone and the application of a metabolic restorative (MR; Metabolase ®). One hundred and twenty females were randomly assigned to one of four treatments: T1: Continuous suckling (CS; n = 29), T2: CS + MR (n = 29), T3: CS + Male Effect (ME; n = 32), and T4: CS + MR + ME. The percentage of females in ovulation, weight changes among females and lambs, the onset of estrus, calving, fecundity, and prolificacy were also determined. The ovulation percentage was higher in CS + ME and CS + MR + ME (75.0 and 73.3%) than in the other treatments. Weight changes in females and lambs were different among periods. The onset of estrus was similar for CS and CS + MR (25.9 ± 1.9 and 25.7 ± 0.7 h, respectively). The calving percentage was higher for CS + MR (86.2%) than other treatments. Male presence positively affected the postpartum cyclic ovarian re-establishment and the metabolic restorative could even improve the fertility of hair ewes in continuous suckling with similar hormone protocol.

To evaluate the response of the "male effect" and "temporary weaning" on the synchronization of postpartum ovarian activity in Pelibuey ewes, an experiment was carried out using 78 Pelibuey ewes with suckling lambs. The ewes were separated from their offspring for 48 hours and randomly assigned to one of four treatments derived from the arrangement of two factors, "male effect" and "temporary weaning", each at two levels. Treatments were: T1 (n = 20) control ewes, without "male effect" and without "temporary weaning"); T2 (n = 19) ewes without "male effect" and with "temporary weaning"; T3 (n = 20) ewes with "male effect" and without "temporary weaning"; and T4 (n = 19), ewes with "male effect" and with "temporary weaning". The response to oestrus, return to oestrus, gestation rate and lambing rate were analysed using logistic regression. The onset of oestrus was analysed using survival curves. No significant differences were found for lambing rate and prolificacy among treatments. "Temporary weaning" (T2) and "male effect" (T3) did not influence the response to oestrus, rate and duration of return to oestrus, or gestation rate and fertility, and was similar to the control group (T1). The interaction of "male effect" with "temporary weaning" (T4) increased the response to oestrus, reduced the rate and duration of return to oestrus, and the gestation rate, but increased fertility. Synchronizing post-partum ovarian activity with "male effect" and "temporary weaning" reduces the onset of oestrus and the rate of return to oestrus, but increases the response to oestrus and fecundity in Pelibuey ewes.

ABSTRACT The aim of this research was to evaluate the effect of partial substitution of vitamin E (VE) by grape seed extract (GSE) on glutathione peroxidase activity (GPxA), nitric oxide (NO) concentration and lipid peroxidation [malondialdehyde (MDA) concentration] in the plasma, lungs, heart and liver, and live performance of broilers raised at 2278 m of altitude. One-d-old Ross 308 male chickens (n = 420) were randomly distributed into three treatments: Control-AL (basal diet containing 40 IU of VE and fed ad libitum; AL), Control-FR (basal diet and feed restriction; FR) and GSE-AL [basal diet containing 10 mg of GSE (equivalent to 30 IU VE) plus 10 IU of VE and fed AL]. The data were analyzed using one-way analysis of variance. Glutathione peroxidase activity, and NO and MDA concentrations in the plasma were evaluated on d 46. On d 47, MDA was evaluated in the lungs, heart and liver. Live performance parameters were recorded weekly. There were no significant differences (p>0.05) in live performance and NO concentration among treatments. Birds from the GSE-AL treatment presented the lowest (p<0.05) GPxA, the highest (p<0.05) MDA concentration in the plasma, heart and liver, and intermediate MDA concentration in the lungs. Our results suggest that GSE may partially replace VE in broiler diets without impairment of live performance. However, further research is required to determine the optimal level of dietary GSE inclusion to reduce lipid peroxidation in the plasma, lungs, heart, and liver of broilers raised at 2278 m of altitude.

In this study it was investigated whether the effect of administration of Recombinant Bovine Somatotropin (bST) (two days before the end of progestin treatment) on synchronizing estrus, estrus, fertility, prolificacy and mode of delivery in Pelibuey sheep. It was an inserted a intravaginal device impregnated with progesterone (P4 CIDR 0.3 g) for nine days on180 sheep with 4 ± 0.32 years of age, the sheep were randomly assigned to one of three treatments: T1= CIDR (n= 60), T2= +250 mg of bST CIDR (n= 60) and T3= CIDR+300 48 IU eCG hours before the end of progestin (n= 60). Results showed no difference (p>0.05) between treatments in estrus synchronization response, fertility and prolificacy. The time to onset of estrus was lower (p<0.05) when applying bST (31.95 ± 2.85 h), with respect to the application of progesterone (43.67 ± 3.55 h). The number of ewes with triplets was higher (p<0.05) when applying bST (32.73 %) and less where it was applied eCG (13.47 %). The administration of 250 mg of bST in Pelibuey sheep, two days before the end of progestin, reduces the time to onset of estrus and increases the proportion of triplets.

Con la finalidad de estudiar si la administración de la Somatotropina Bovina Recombinante (bST) dos días antes del retiro del progestágeno, tiene efecto en la sincronización de estros, inicio del estro, fertilidad, prolificidad y tipo de parto en ovejas Pelibuey, a 180 ovejas de 4,0 ± 0,32 años de edad, se les inserto un dispositivo intravaginal impregnado con progesterona (CIDR P4 0,3 g), por nueve días. Dos días antes del retiro del dispositivo, las ovejas se asignaron aleatoriamente a uno de tres tratamientos: T1 = CIDR(n=60); T2= CIDR+ 250 mg de bST (n= 60) y T3= CIDR+300 UI eCG 48 horas antes del retiro del progestágeno (n= 60). La respuesta en la sincronización de estros, fertilidad y prolificidad no fue diferente (p>0,05) entre tratamientos. el tiempo a inicio del estro fue menor (p<0,05) al aplicar bST (31,95 ± 2,85 h) con respecto a la administración de progesterona (43,67 ± 3,55 h). La cantidad de ovejas con partos triple fue mayor (p<0,05) al aplicar bST (32,73 %) y menor al administrar eCG (13,47 %). La administración de 250 mg de bST en ovejas Pelibuey, dos días antes retirar el progestágeno, reduce el tiempo a la presentación del estro y aumenta la proporción de partos triples.

The purpose of this study was to determine the effect of suckling, postpartum (PP) synchronization protocol and the ram effect on reproductive performance of hairy sheep. Isolated from the rams, 96 ewes were randomly assigned to one of two groups at lambing (n=48): continuous suckling for 18 h (Ac) and controlled suckling for 30 minutes twice a day (Lc). On day 35 PP, both groups were synchronized with CIDR (Controlled Internal Drug Release) for 10 days, 48 hours before CIDR removal, 7,5 mg of dinoprost was administered and the effect of the ram (Ca) 48 hours before and at the time of CIDR removal were tested. We determined progesterone (P4) por radioimmunoassay at 30, 35, 50, 55 y 64 days PP. The ewes were inseminated intrauterine by abdominal laparoscopy 12 to 15 hours after estrus onset. The response variables were: percentage of ovulation before 35 days PP, time of estrus onset, pregnancy rate, prolificacy, fecundity and live weight of the ewes and their lambs. The information obtained was analyzed using logistic regression and Poisson, chi-square test, survival curves and repeated measures analysis. The percentage of ewes that ovulated before 35 days PP was higher (p<0.05) in Lc (89.6 %) than Ac (52.1 %). The weight of the ewes was similar (p>0.05) between treatments. The weight of lambs was higher (p<0.05) in Ac after 41 days PP and there was no mortality during lactation. After CIDR removal all ewes showed estrus, being those of Lc (p<0.05) the first to manifest estrous behavior (50 hours). Pregnancy rate, prolificacy and fecundity were not different between treatments and averaged 82.3, 1.84 and 1.51 %, respectively. The results indicate that controlling lactation increases and concentrates the number of ewes that ovulated before 35 days PP. All ewes responded to the synchronization postpartum and the ram effect showing estrous behavior and only one ewe presented corpora lutea of shortened lifespan.

En este estudio se analizó la respuesta reproductiva de las ovejas de pelo al efecto del amamantamiento y a un protocolo de sincronización posparto (PP) con hormonas, así como el efecto del carnero. Aisladas de los carneros, 96 ovejas fueron clasificadas aleatoriamente al parto en dos grupos (n=48): un primer grupo con amamantamiento continuo por 18 horas (Ac) y un segundo grupo de lactancia controlada con amamantamiento por 30 min 2 veces día-1 (Lc). En el día 35 PP se les colocó a las ovejas un CIDR (Controlled Internal Drug Release) por 10 días, 48 horas antes de retirarlo se les aplicó 7,5 mg de dinoprost y se probó el efecto del carnero (Ca) 48 h antes y al momento de retirar el CIDR. Se determinó el contenido de progesterona (P4) por RIA a los 30, 35, 50, 55 y 64 días PP. Las ovejas fueron inseminadas vía intrauterina con laparoscopio abdominal 12 a 15 horas después de iniciado el estro. Las variables de respuesta fueron: porcentaje de ovulación antes de los 35 días PP, hora de inicio del estro, tasa de gestación, prolificidad, fecundidad y pesos de las ovejas y sus crías. La información obtenida fue analizada mediante regresión logística y de Poisson, prueba de chi cuadrado, curvas de supervivencia y análisis de medidas repetidas. El porcentaje de ovejas que ovularon antes de los 35 días PP fue mayor (p<0,05) en Lc (89,6 %) con respecto a Ac (52,1 %). El peso de las ovejas fue similar (p>0,05) entre tratamientos. El peso de los corderos fue mayor (p<0,05) en Ac a partir de los 41 días PP y no hubo mortalidad de corderos. Después de retirar el CIDR todas las ovejas manifestaron estro, siendo las de Lc las que primero lo hicieron (p<0,05), a las 50 horas. La tasa de gestación, prolificidad y fecundidad no difirieron entre tratamientos y los promedios fueron de 82,3; 1,84 y 1,51 %, respectivamente. Los resultados demuestran que la lactancia controlada aumenta y concentra el número de ovejas que ovularon antes de los 35 días PP. En cuanto a la sincronización posparto y al efecto macho, todas las ovejas respondieron al manifestar comportamiento estral y solo una oveja presentó cuerpo lúteo de vida media corta.