132 Effect of treatment with follicle-stimulating hormone on in vitro embryo production of Gyr (Bos indicus) calves, pubertal heifers and adult cows

Abstract

The aim of this study was to evaluate the effect of FSH treatment on the in vitro embryo production of Gyr (Bos indicus) calves (3-10 months), pubertal heifers (16-21 months) and adult cows. Thirty females were used: 10 calves, 10 pubertal heifers (puberty was determined by the presence of a corpus luteum) and 10 cows. The animals were distributed as follows: calves: control (C-C, n = 5) and with FSH (FSH-C, n = 5); heifers: control (C-H, n = 5) and with FSH (FSH-H, n = 5); and adult animals: control (C-A; n = 5) and with FSH (FSH-A; n = 5). All animals received an intravaginal progesterone device (calves-Primer PR®, Agener União, Brazil; heifers and cows-Prociclar®, Ceva Saúde Animal, Brazil) and oestradiol benzoate (calves and heifers: 1 mg, cows: 2 mg; Fertilcare Sincronização®, MSD Saúde Animal, Brazil) on Day 0. The control animals of each category received no additional treatment. The FSH-C received 80 mg IM of FSH (Folltropin®, Vetoquinol, Mairipora, Brazil), performed in 4 injections twice a day in decreasing doses [25 mg (Day 4, p.m.), 25 mg (Day 5, a.m.), 15 mg (Day 5, p.m.), and 15 mg (Day 6, a.m.); coasting period: 24 h]. The FSH-H received 100 mg IM of FSH, performed in 4 injections twice a day in decreasing doses [30 mg (Day 4, p.m.), 30 mg (Day 5, a.m.), 20 mg (Day 5, p.m.), and 20 mg (Day 6, a.m.); coasting period: 24 h]. The FSH-A received 140 mg IM of FSH, performed in 4 injections twice a day in decreasing doses [40 mg (Day 4, a.m.), 40 mg (Day 4, p.m.), 30 mg (Day 5, a.m.), and 30 mg (Day 5, p.m.); coasting period: 48 h]. On Day 7 the intravaginal devices were removed and all animals were submitted to epidural anaesthesia (2% lidocaine) followed by ovum pickup guided by transvaginal ultrasound (guide EC9-5 Heifer, WTA, Sao Paulo, Brazil; ultrasound S8®, SonoScape, Shenzhen, China). The recovered oocytes were sent to a commercial laboratory for the in vitro embryo production. The obtained data were analysed by the GLIMIX procedure of SAS^® (SAS Institute Inc., Cary, NC, USA; means are presented as standard error of the mean. The oocyte recovery rate was lower (P = 0.01) for calves and heifers treated with FSH (FSH-C: 42.8%; FSH-H: 55.2%) when compared with control calves and heifers (C-C: 65.1%; C-H: 81.1%); however, no difference was observed for cows (C-A: 63.7%; FSH-A: 63.1%). The number of viable oocytes differed according to the category (P = 0.001); calves and cows had higher numbers of viable oocytes (calves: 11.6 ± 0.7; cows: 11.7 ± 0.9) when compared with heifers (23.4 ± 0.6). The number of cleaved oocytes increased (P = 0.03) when calves (FSH-C: 8.0; C-C: 5.8) and cows (FSH-A: 8.8, C-A: 6.0) were treated with FSH. Cleavage rate was higher (P = 0.05) when animals of all categories were treated with FSH (calves = 52.7%; heifers = 68.0%; cows = 67.9%), when compared with nontreated animals (45.8%; 60.1%; 51.8%, respectively). The number of blastocysts per ovum pickup increased (P = 0.04) when calves (FSH-C: 3.2; C-C: 1.5) and cows (FSH-A: 5.8; C-A: 2.8) were treated with FSH. The number of vitrified embryos (percentage of blastocysts surviving vitrification) increased (P = 0.02) when calves (FSH-C: 2.6; C-C: 1.0) and cows (FSH-A: 5.0; C-A: 2.4) were treated with FSH. These results show that treatment with FSH increases the efficacy of in vitro embryo production in Gyr calves and cows.