title: LF8_B
organism: Bos taurus
description: Protocols: Eighteen 24- to 30-month-old cross-bred heifers (Charolais, Limousin, Aberdeen Angus and Simmental) had their oestrus cycles synchronized and were inseminated using a fixed-time AI protocol. The heifers were blocked by breed and age into three distinct treatment groups and inseminated with semen from 3 bulls from each treatment, namely, low CN (7 heifers), intermediate CN (6 heifers), and high CN (5 heifers). The synchronization protocol entailed a seven-day intravaginal progesterone device (CIDR®), accompanied by intramuscular administration of gonadotrophin-releasing hormone (Ovarelin; 2 mL) at CIDR® insertion. Prostaglandin F2 alpha (Enzaprost; 5 ml) was administered intramuscularly to induce luteolysis 24 h before CIDR removal. At 54 (+/- 1 ) h post-CIDR® removal, heifers received a single fixed-time insemination of frozen–thawed semen. Ovarelin (2 mL) was administered intramuscularly at the time of AI. Twelve hours post insemination, heifers were slaughtered at a commercial abattoir. Reproductive tracts were promptly collected post-mortem, and the uterine horn on the side of the ovulated ovary was longitudinally opened with sterile scissors. Tissue samples were acquired from the inter-caruncular region of the uterine horn near the uterine body using a sterile 8-mm biopsy punch. The endometrium was then dissected away from the myometrium. Endometrium samples were flash frozen in liquid nitrogen, transported to the laboratory, and stored at −80°C. Total RNA isolation was conducted by Biomarker Technologies   RNA library preparation was conducted by Biomarker Technologies