Ivan Júnior Ascari

Nursing regimens: Effects on body condition, return to postpartum ovarian cyclicity in Santa Ines ewes, and performance of lambs

The effects of nursing regimens on the body condition, onset of ovarian cyclicity postpartum and weaning weight of lambs were assessed in Santa Ines ewes. Thirty-two ewes were blocked according to parity, number of lambs, and body weight at lambing and within each block randomly allocated to treatments: continuous nursing (CN), controlled nursing (CN2) with two daily feedings for an hour after the 10th day postpartum, or early weaning (EW) with total separation from the lambs after the 10th day. The animals were evaluated from the 12th day postpartum until the first estrus or until 60th day. The dry matter and nutrients intake did not differ among treatments (P>0.05) but did differ over time (P<0.01). The weight, body condition score, serum concentrations of non-esterified fatty acids and prolactin, the percentages of ewes in estrus, of ewes that ovulated within 60th day and had ovulation silent, the period from lambing to estrus, ovulation and follicle with a diameter ≥5mm and the maximum follicular diameter did not differ (P>0.05) among the treatments. The percentage of ovulation until 30th day was greater (P<0.05) in the EW group. The percentage of short luteal phases was higher in the CN2 and EW groups (P=0.07) and normal luteal phases were higher in the CN group (P=0.01). Lamb weight weaning was lower in the EW group (P<0.05). It is possible to use CN to obtain lambing periods less than eight months in Santa Ines ewes, with the advantages of simpler management and higher lamb weaning weights.

Development of bovine embryos in vitro in coculture with murine mesenchymal stem cells and embryonic fibroblasts

Despite the progress on development of new culture media, in vitro-produced embryos still display lower quality when compared to the in vivo-produced counterparts. Coculture has been reconsidered as an alternative to improve embryo quality. Mesenchymal stem cells (MSC) and murine embryonic fibroblasts (MEF) have been extensively used as feeder layers due to their capacity to release growth factors. In the present study we investigated the effect of these feeder layers in oocyte maturation and/or embryo development under in vitro conditions. Oocytes were matured in control (CTRL) conditions or in coculture with MSC or MEF. In vitro fertilization and embryo culture until fourth day were performed in CTRL condition for all groups. Embryos from fourth day on were then cultured until the eighth day in CTRL or in coculture system. No significant differences for metaphase II stage and apoptosis in oocytes were found among the groups. There was also no difference among the groups when we evaluated blastocyst formation on the seventh and eighth day, with exception of a higher hatched blastocyst rate in the group maturated and cultivated in CTRL condition when compared to the group matured and cocultured with MSC. Also no difference was observed in the number of cells in the whole embryos, in the inner cell mass, in the trophoblast and at apoptotic stage on the eighth day. We conclude that coculture with MSC or MEF during maturation and/or embryo development do not enhance the in vitro production of bovine embryos.

69 AGE AT PUBERTY AND REPRODUCTIVE DEVELOPMENT OF LAMBS FED SUNFLOWER CAKE

The objective of this study was to evaluate the effects of lipid inclusion, represented by sunflower cake (SC), on the performance, age at puberty, ovarian follicular development, and metabolic panel of prepubertal lambs. Thirty-five crossbred Santa Ines lambs were used [initial body weight (BW) 21.5 ± 1.6 kg and age 138 ± 3 days]. Four SC inclusions were tested: 0% SC, n = 9; 15% SC, n = 9; 30% SC, n = 9; and 45% SC, n = 8, within the dry matter of the diet. The diets were offered to the lambs until they reached 43.6 ± 0.8 kg; after reaching this BW they were slaughtered. Dry matter intake and performance were analysed. The number of follicles, the diameter of the larger follicle, and the total cholesterol serum concentration were evaluated one day before slaughtering. The serum progesterone concentration was analysed every 6 days after the animals reached 30 kg. Puberty was determined when the progesterone concentration reached = 1 ng mL–1 for the first time. The animals were randomly confined in individual pens. To study the significant variable and its effects on the treatments, regression analysis was performed. The number of follicles visualised in the ovary through ultrasound and after slaughtering was analysed by Proc Genmod. Spearman correlation coefficient of the number of follicles obtained through the in vivo ultrasound technique and by the count of follicles in the ovary postmortem. SAS software was used (SAS Institute Inc., Cary, NC, USA). Daily dry matter intake (1.3 ± 0.5, 1.4 ± 0.5, 1.3 ± 0.5, and 1.3 ± 0.6 kg) and weight gain (0.19 ± 0.02, 0.23 ± 0.02, 0.19 ± 0.02, and 0.18 ± 0.02 kg) in the treatments of 0, 15, 30, and 45% of SC, respectively, presented no significant differences (P > 0.05). Total cholesterol serum concentration linearly increased (y = 73.1784 + 0.7206x), (R2 = 0.8477; P   0.05), whereas the number of follicles = 3 mm of diameter was correlated (r = 0.56; P  5 mm (0.5 ± 0.3, 0.7 ± 0.3, 0.8 ± 0.2, and 0.6 ± 0.3), and the diameter of the largest follicle (0.45 ± 0.03, 0.45 ± 0.04, 0.43 ± 0.03, and 0.40 ± 0.04 cm) verified through ultrasound, age at puberty (204 ± 11, 211 ± 13, 211 ± 13, 196 ± 11, 218 ± 11 days), and the weight at puberty (33.5 ± 1.5, 33.5 ± 1.7, 32.2 ± 1.5, and 33.5 ± 1.5 kg) in the treatments 0, 15, 30, and 45% SC, respectively, did not differ (P > 0.05), although the progesterone concentration presented a linear increase (y = 1.4783 + 0.02826x; P   3 mm (0.91 ± 0.2, 0.91 ± 0.2, 0.97 ± 0.2, and 0.88 ± 0.2) did not differ (P > 0.05). In conclusion, the use of SC in the lamb’s diet positively affected the progesterone concentration and the development of follicles <3 mm of diameter, which presented an optimal level at 23.4% SC inclusion.

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.