Acosta Diego Andres Velasco, Schneider Augusto, Jacometo Carolina Bespalhok, Rincon Joao Alvarado, Cardoso Felipe, Corrêa Marcio Nunes
The Colombian Corporation for Agricultural Research (CORPOICA), Bogotá, 250047, Colombia; Research Center, Education and Extension in Livestock (NUPEEC), College of Veterinary Medicine, Federal University of Pelotas, Pelotas, RS, Brazil.
Department of Nutrition, College of Nutrition, Federal University of Pelotas, Pelotas, RS, Brazil; Research Center, Education and Extension in Livestock (NUPEEC), College of Veterinary Medicine, Federal University of Pelotas, Pelotas, RS, Brazil.
Theriogenology. 2017 Dec;104:164-172. doi: 10.1016/j.theriogenology.2017.08.024. Epub 2017 Aug 26.
The aim of this study was to determine the effect of pre-partum injections of bovine somatotropin (bST) in dairy heifers on metabolic markers and the steroidogenic potential of the first postpartum dominant follicle. Heifers were assigned to two groups: bST (ST; n = 29), that received two doses of bST (500 mg/dose) at -28 and -14 days relative to calving; and control (CTL; n = 30), that did not received bST. Follicular development was monitored via ultrasound every 3 days starting at 8 days in milk (DIM) in a subset of 20 heifers until the day the first large follicle reached a diameter of 16 mm. From these cows follicular fluid was aspirated and the follicular cells recovered (ST; n = 8 and CTL; n = 10). Blood samples were collected weekly for all heifers. Follicular fluid IGF-I concentrations of the first postpartum dominant follicle was higher (P = 0.05) in ST (87.1 ± 7.7 mg/mL) than CTL cows (64.3 ± 6.8 mg/mL). Also, E2 concentration in the follicular fluid was higher (P = 0.02) for ST (199.7 ± 55.9 ng/mL) than CTL cows (74.5 ± 37.7 ng/mL). The expression of LHCGR and STAR mRNA in follicular cells was higher (P < 0.05) in ST than CTL cows. Nonetheless, HSD3B, P450scc, P450c17, IGFr and CYP19A1 mRNA expression was not different between groups (P > 0.05). Serum IGF-I concentration was higher in ST treated heifers during the pre-partum period (P = 0.01) and no difference was observed in the postpartum period (P = 0.19). In conclusion, pre-partum bST treatment in dairy heifers increased intrafollicular IGF-I and expression of LHCGR and STAR mRNA in follicular cells of the first postpartum dominant follicle. These changes were associated to increased intrafollicular and serum E2 concentration, which can potentially increase the chance of ovulation of the first follicular wave.
本研究的目的是确定产前注射牛生长激素（bST）对奶牛小母牛代谢指标以及产后首个优势卵泡类固醇生成潜能的影响。小母牛被分为两组：bST组（ST；n = 29），在产犊前-28天和-14天接受两剂bST（500毫克/剂）；对照组（CTL；n = 30），不接受bST。从产后8天（DIM）开始，每3天通过超声对20头小母牛的一个子集进行卵泡发育监测，直至首个大卵泡直径达到16毫米的那天。从这些母牛中抽吸卵泡液并回收卵泡细胞（ST组；n = 8，CTL组；n = 10）。每周为所有小母牛采集血样。产后首个优势卵泡的卵泡液IGF-I浓度在ST组（87.1±7.7毫克/毫升）高于CTL组母牛（64.3±6.8毫克/毫升）（P = 0.05）。此外，ST组卵泡液中的E2浓度（199.7±55.9纳克/毫升）高于CTL组母牛（74.5±37.7纳克/毫升）（P = 0.02）。卵泡细胞中LHCGR和STAR mRNA的表达在ST组高于CTL组母牛（P < 0.05）。然而，HSD3B、P450scc、P450c17、IGFr和CYP19A1 mRNA表达在两组间无差异（P > 0.05）。产前接受ST处理的小母牛血清IGF-I浓度较高（P = 0.01），产后未观察到差异（P = 0.19）。总之，奶牛小母牛产前bST处理增加了产后首个优势卵泡卵泡内IGF-I以及卵泡细胞中LHCGR和STAR mRNA的表达。这些变化与卵泡内和血清E2浓度升高有关，这可能会增加首个卵泡波排卵的机会。
