Recent advances in ovulation synchronization and superovulation in ...

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Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil. Effect of single or repeated insulin administrations before and after mating on litter size in Anglo-Nubian goats I.M.T. Lima, A.L. Souza, I.J. Arruda, M.R.C. Rodrigues, A.M. Silva, A.N. Godinho, L.D. Gonçalves, A.A. Araújo, D.I.A. Teixeira, D. Rondina Programa de Pós-Graduação em Ciências Veterinárias, Faculdade de Veterinária, Universidade Estadual do Ceará, Fortaleza, CE, Brasil. Introduction In goats, as well as other ruminants, insulin is a crucial key mediator for reproductive performance, and is involved in the follicular development, steroidogenesis, oocyte maturation and embryo development processes (1). Recent studies reported increasing ovulation rate (1) and viable embryo production in superovulated goats (2) treated with repeated doses of insulin. Moreover, several authors working with cattle suggest that insulin contributes to a better conception rate and to the enhancement of prolificacy (3, 4). However, there is no scientific information available in goats. Thus, the aim of this study was investigate the effect of insulin administration on litter size in Anglo-Nubian goats. Materials and Methods Thirty-one Anglo-Nubian goats with similar live weight (32.25 ± 0.77 kg; P > 0.05) and age (27.9 ± 0.98 months; P > 0.05) (mean ± SEM) had their estrus synchronized by two i.m. administrations of 100 µg cloprostenol, 11 days apart. Twenty-four hours after the second injection, two fertile Anglo-Nubian bucks were mixed with the goats to detect estrus and mating. In this period, animals were treated subcutaneously with human long acting insulin (0.2UI/kgBW/day). Animals from the first group (Ins.I) (n = 10) were submitted to a unique insulin administration at second cloprostenol injection (Day 0). In second group (Ins.III) (n = 11), females received three insulin administrations (Day 0, Day 3 and Day 6), while the goats of third group (Ins.IV) (n = 10) were treated with four insulin doses (Day 0, Day, 3, Day 6 and Day 9). Immediately after kidding, litter size (litter size/dam that gave birth), type of parturition (simple or multiple) and weight at birth were recorded. All animals were maintained in similar feeding and management conditions. The Insulin effect was analyzed by the SAS GLM procedure. Comparison between Insulin means was performed by the Duncan test and between sexes by t test. Values were expressed as mean ± SEM. Results and Discussion Litter size was similar between groups (P > 0.05) showing a mean respectively for Ins.I, Ins.III and Ins.IV of 2.0 ± 0.45, 1.6 ± 0.24 and 1.6 ± 0.24. These data are not in agreement to (3) that working with cattle, verified that continuous elevations in plasma insulin rates are more important than the progesterone to the early embryo development and, consequently, to obtain greater prolificacy rates. Other authors (4) reported in lactating dairy cows that IGF-I, positively correlated to the plasma insulin rates, increases embryo survival and, thus, the prolificacy rates. Our findings also show a similar proportion of multiple parturition type (P > 0.05) (mean 58.82 ± 12.30%) and for the weight at birth between sex in each group (P > 0.05) and among groups in female kids (mean: 2.88 ± 0.06 kg; P > 0.05). However, in the male kids Ins.I had a lower weight at birth when compared to Ins.IV (2.77 ± 0.53 kg vs. 3.23 ± 0.16 kg; P < 0.05). Based on our results, it was concluded that single or repeated insulin administrations before and after mating did not affect the litter size in Anglo-Nubian goats. References (1) Selvaraju S, Agarwal SK, Karche SD, Srivastava SK, Majumdar AC, Shanker U. 2002. Anim Reprod Sci, 73:141-149; (2) Souza AL, Galeati G, Almeida AP, Arruda IJ, Govoni N, Freitas VJF; Rondina D. 2008. Reprod Domest Anim, 43:218-221; (3) Mann GE, Green MP, Sinclair KD, Demmers KJ, Fray MD, Gutierrez CG, Garnsworthy PC, Webb R. 2003. Anim Reprod Sci, 79:71-79; (4) Block J, Hansen PJ. 2007. Theriogenology, 67:1518-1529. E-mail: dora.uece@gmail.com Anim. Reprod., v.6, n.1, p.221, Jan./Mar. 2009 221
222 Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil. Postpartum ovarian activity by endocrine profiles in Colombian Sanmartinero cows G.M. Baez, H.A. Grajales Laboratory of Hormones. Department of Animal Production. National University of Colombia Ciudad Universitaria, Bogota, DC, Colombia. Introduction There are at least seven Colombian native breeds of cattle spread along the country. Several studies have been made regarding some reproductive aspects in Costeño Con Cuernos (1) and Romosinuano (2, 3) breeds. Those animals have shown adaptation to the environmental conditions in tropics, in terms of reproductive performance. Previously works about luteal function and follicular dynamics associated with the first spontaneous estrous cycles in postpartum cows have been made (4). The aim of this study was to describe levels of progesterone and estradiol associated with ovarian function during postpartum period in Sanmartinero cows. Materials and Methods 15 suckling cows calving simultaneously were studied since day 7 postpartum, and during all over their postpartum period. Blood samples were taken three times a week and progesterone (P4) and estradiol (E2) serum levels during the onset of estrous activity were measured by radioimmunoassay, using human commercial kits (MP Biomedicals Inc, Costa Mesa, CA). No extraction was made. Body condition was evaluated, in a five-point scale [1 = emaciated to 5 = obese, (5)], in order to determine the energy balance. Results and Discussion Minimum energy balance (nadir) was presented approximately on day 60 after calving (Fig. 1), being coincident with the interval from parturition to first postpartum ovulation (60.6 ± 24.4 days). All cows had a short luteal phase after first ovulation, with an average interval of 7.18 ± 0.75 days between first and second ovulation that was associated with less progesterone than was second ovulation (Fig. 2). These results are in agreement with those found in other Colombian native cattle (1). Signs of estrus were less obvious or absent preceding first ovulation. Estradiol profiles evidenced the presence of follicular waves since early lactation as estradiol waves due to secretion by follicles. Estradiol levels tended to increase through lactation, from 26.43 ± 5.6 pg/ml between first and second weeks after calving, to 43.76 ± 6.5 pg/ml at the first ovulation (R 2 = 0.436) in a consistent pattern (Fig. 2). This study allows confirming previous findings regarding some aspects of endocrine patterns during postpartum period and its relation with nutritional status. Figure 1. Average body condition score Figure 2. Postpartum endocrine profiles References (1) Baez GM, Grajales HA, Pérez JE. 2007. Liv Res Rural Dev, 19:132; (2) Grajales H, Hernández A, Prieto E. 2006. Liv Res Rural Dev, 18:144; (3) Grajales H, Hernández A. 2008. Liv Res Rural Dev, 20:39. (in Spanish); (4) Perry RC, Corah LR, Kiracofe GH, Stevenson J S,Beal WE. 1991. J Anim Sci, 69:2548; (5) Butler WR. 2003. Liv Prod Sci, 83:211. Acknowledgments: CORPOICA La Libertad, for technical and financial support. Email: gmbaezs@unal.edu.co Anim. Reprod., v.6, n.1, p.222, Jan./Mar. 2009
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