Figure 6.
Experimental design. Lactating beef cows (n =44) were synchronized with the Co-synch + controlled internal drug release (CIDR) protocol. Administration of gonadotropin-releasing hormone (GnRH) and CIDR on Day -9; prostaglandin F2α (PGF) on Day -2; and fixed timed artificial insemination and GnRH administration on Day 0. Cows were divided into two groups: those artificially inseminated (AI) with live sperm (n=36) or receiving dead sperm (n=8). Control cows received a CIDR from Day 17 until Day 24 of gestation to maintain elevated circulating concentrations of progesterone. Blood (BS) was collected on Days 0, 17, and 24. Pregnancy status was determined by transrectal ultrasound (US) on Days 30 and 56 of gestation.