Equine chorionic gonadotropin improves the efficacy of a progestin-based fixed-time artificial insemination protocol in Nelore (Bos indicus) heifers

Animal Reproduction Science
M F Sá FilhoP S Baruselli

Abstract

A total of 177 Nelore heifers were examined by ultrasonography to determine the presence or absence of a corpus luteum (CL) and received a 3mg norgestomet ear implant plus 2mg of estradiol benzoate i.m. On Day 8, implants were removed and 150 microg of d-cloprostenol i.m. was administered. At the time of norgestomet implant removal, heifers with or without CL at the time of initiating treatment were assigned equally and by replicate to be treated with 0IU (n=87) or 400IU (n=90) eCG i.m. All heifers received 1mg of EB i.m. on Day 9 and were submitted to fixed-time artificial insemination (FTAI) 30-34h later. The addition of eCG increased the diameter of the largest follicle (LF) at FTAI (10.6+/-0.2mm vs. 9.5+/-0.2mm; P=0.003; mean+/-SEM), the final growth rate of the LF (1.14+/-0.1mm/day vs. 0.64+/-0.1mm/day; P=0.0009), ovulation rate [94.4% (85/90) vs. 73.6% (64/87); P=0.0006], the diameter of the CL at Day 15 (15.5+/-0.3mm vs. 13.8+/-0.3mm; P=0.0002), serum concentrations of progesterone 5 days after FTAI (6.6+/-1.0 ng/ml vs. 3.6+/-0.7ng/ml; P=0.0009), and pregnancy per AI [P/AI; 50.0% (45/90) vs. 36.8% (32/87); P=0.04]. The absence of a CL at the beginning of the treatment negatively influenced the P/AI [30.2% (16/53) vs. 49....Continue Reading

References

Sep 1, 1987·Journal of Animal Science·D J ByerleyR E Short
May 1, 1996·Biology of Reproduction·L H AndersonM L Day
Jan 5, 2002·Theriogenology·M BinelliP S Baruselli
Nov 17, 2004·Journal of Dairy Science·E J GarbarinoW W Thatcher
Nov 4, 2005·Journal of the American Veterinary Medical Association·Jorge A HernandezWilliam W Thatcher
Mar 5, 2008·Theriogenology·L U GimenesP S Baruselli

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Citations

May 23, 2014·Animal : an International Journal of Animal Bioscience·G A Bó, P S Baruselli
Nov 6, 2012·Theriogenology·A D P RodriguesJ L M Vasconcelos
May 24, 2013·The Journal of Reproduction and Development·Irina Garcia-Ispierto, Fernando López-Gatius
May 10, 2016·Theriogenology·Nelcio Antonio Tonizza de CarvalhoPietro Sampaio Baruselli
Oct 7, 2016·PloS One·Liza Margareth Medeiros de Carvalho SousaPaula de Carvalho Papa
Oct 31, 2012·Reproduction, Fertility, and Development·Luciana A FátimaPaula C Papa
Jun 15, 2016·Journal of Veterinary Science·Rafael Herrera AlvarezPaolo Bartolini
Aug 1, 2012·Reproduction in Domestic Animals = Zuchthygiene·P S BaruselliG A Bó

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