Institute of Animal Science, Beef Cattle Research Center, Sertãozinho, SP, 14160-970, Brazil.
São Paulo State University (UNESP), Faculty of Agricultural and Veterinarian Sciences, Jaboticabal, SP, 14884-900, Brazil.
Trop Anim Health Prod. 2024 Oct 25;56(8):357. doi: 10.1007/s11250-024-04205-6.
The aim of this study was to evaluate the effect of injectable progesterone administration before ovum pick-up (OPU) on in vitro embryo production (IVEP) and pregnancy rate in prepubertal Nellore heifers. Twenty-three Nellore females, 13.04 ± 0.8 months of age, were randomly assigned to two groups: control group (no progesterone application) and progesterone group (intramuscular administration of 1 mL [150 mg/mL] progesterone 7 days before OPU). The second OPU was performed after 28 days (crossover between groups). After OPU, oocytes were selected for IVEP and a sample was fixed in 4% paraformaldehyde. Viable oocytes were subjected to immunofluorescence staining for IGFBP2 and caspase-3. For each oocyte, one image was generated per channel (A555 and A488 filters) and analyzed with the ImageJ program for the quantification of fluorescence intensity (in pixels). The produced embryos were transferred to multiparous Nellore cows and pregnancy was diagnosed by ultrasound 30 days after transfer. Data were analyzed using the MIXED and GLIMMIX procedure of SAS. Treatment with injectable progesterone had no effect on the number or size of the antral follicles of heifers. No differences between the control and progesterone groups were observed for total number of aspirated oocytes (P = 0.78), viable oocytes (P = 0.80), cleavage rate (P = 0.60), or blastocyst rate (P = 0.56). There were no differences in pixel intensity between the two groups, nor in the levels of IGFBP2 or caspase-3. However, a difference was observed in the pregnancy rate of embryos produced from heifers of the progesterone group (42.1%; 32/76) when compared to the rate of embryos produced from control heifers (28.4%; 23/81) (P = 0.02). The use of injectable progesterone before OPU in prepubertal Nellore heifers does not improve IVEP but increases the pregnancy rate after transfer.
本研究旨在评估在卵母细胞抽吸（OPU）前注射孕激素对青春期前尼洛里小母牛体外胚胎生产（IVEP）和妊娠率的影响。23 头尼洛里小母牛，年龄 13.04±0.8 个月，随机分为两组：对照组（未应用孕激素）和孕激素组（OPU 前 7 天肌内注射 1 毫升[150mg/mL]孕激素）。28 天后进行第二次 OPU（组间交叉）。OPU 后，选择卵母细胞进行 IVEP，并取样本用 4%多聚甲醛固定。活卵母细胞进行 IGFBP2 和 caspase-3 的免疫荧光染色。对于每个卵母细胞，每个通道（A555 和 A488 滤光片）生成一个图像，并使用 ImageJ 程序分析荧光强度（像素）。产生的胚胎被转移到多胎尼洛里奶牛中，在转移后 30 天通过超声诊断妊娠。数据采用 SAS 的 MIXED 和 GLIMMIX 程序进行分析。注射用孕激素处理对小母牛的窦卵泡数量或大小没有影响。对照组和孕激素组之间在总抽吸卵母细胞数（P=0.78）、活卵母细胞数（P=0.80）、卵裂率（P=0.60）或囊胚率（P=0.56）方面均无差异。两组之间的像素强度无差异，IGFBP2 或 caspase-3 的水平也无差异。然而，孕激素组产生的胚胎妊娠率（42.1%；32/76）与对照组产生的胚胎妊娠率（28.4%；23/81）（P=0.02）存在差异。在青春期前的尼洛里小母牛中，在 OPU 前使用注射用孕激素不会提高 IVEP，但会提高移植后的妊娠率。
