title: Site of PGF2αinjection does not alter effectiveness of the Select Synch + controlled internal drug release and timed artificial insemination protocol.
abstract: Beef Quality Assurance programs have contributed to significant improvements in the wholesomeness of beef available for consumption. Injection site blemishes in the round have declined since the promotion of administering intramuscular injections in the neck. Unfortunately, many producers continue to administer estrus synchronization (ES) drugs in the rump. The objective of this study was to compare the effectiveness of injection site of PGF2α, in ES protocols, on steroid hormone concentrations and pregnancy rates. A Select Synch + 7-day controlled internal drug release ES protocol was conducted with the site of PGF2αinjection alternated between neck and rump in beef cattle (n = 312) at the Ohio State University Agricultural Technical Institute and North Carolina State University. Blood samples (n = 75) were collected at controlled internal drug release insertion and at the time of artificial insemination (AI) to determine if progesterone (P4) and estrogen (E2) concentrations varied due to PGF2αinjection site. All cattle were confirmed pregnant by ultrasonography at approximately 30 and 90 days after insemination in North Carolina and approximately 70 days after insemination in Ohio. Data were analyzed as randomized complete block designs in PROC GLIMMIX with animal as the experimental unit. Differences were declared significant at P < 0.05. Site of PGF2αinjection, in either the neck or rump, did not affect (P > 0.05) overall conception rates in response to AI (58.4% and 55.6%, respectively). Altering PGF2αinjection site did not impact P4, E2 concentrations, or the P4:E2 ratio at AI (P > 0.05). However, cattle inseminated after displaying estrus had greater (P < 0.05) pregnancy rates than timed AI (67.8 vs. 47.5%, respectively). First service conception rates and pregnancy rates were consistent with previous reports. Overall, altering the location of the PGF2αinjection during ES did not change circulating hormone concentrations at AI or pregnancy rates; therefore, cattle producers should follow Beef Quality Assurance guidelines when administering ES protocols.
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh, North Carolina, USA; Department of Animal Science, The Ohio State University Agricultural Technical Institute, Wooster, Ohio, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Pickworth
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh, North Carolina, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Bell
authors.affiliation: Department of Animal Science, The Ohio State University Agricultural Technical Institute, Wooster, Ohio, USA.
authors.forename: W
authors.initials: W
authors.lastname: Greene
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh, North Carolina, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Whisnant
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh, North Carolina, USA. Electronic address: dhpoole@ncsu.edu.
authors.forename: D H
authors.initials: DH
authors.lastname: Poole
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D015237:Dinoprost / Q000008:administration & dosage / Q000494:pharmacology*; D004334:Drug Administration Schedule; D004972:Estrus Detection / Q000295:instrumentation; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000662:veterinary*; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D015237:Dinoprost
keywords: Beef production; Estrus synchronization; Injection site; Quality assurance