title: Embryo production in heifers with low or high dry matter intake submitted to superovulation.
abstract: This study investigated the influence of feed intake on superovulatory response and embryo production of Nelore heifers. Pubertal heifers were kept in a feedlot and were submitted to the same diets, but with different levels of feed consumption: High (1.7 M; n = 20) or Low (0.7 M; n = 19) feed intake. Heifers in the 1.7 M treatment consumed 170% (2.6% of body weight [BW] in dry matter) and the 0.7 M heifers ate 70% (1.1% of BW in dry matter) of a maintenance diet. After 7 wk on these diets, heifers were treated with eight decreasing doses of follicle-stimulating hormone (FSH) given every 12 h, totaling 133 mg Folltropin (Folltropin-V; Bioniche Animal Health, Canada) per heifer. Seven d after AI, heifers had their uteri flushed and embryos were recovered and graded according to the International Embryo Technology Society standards. Data were analyzed using the GLIMMIX procedure of SAS and results are presented as least-squares means ± SEM (P < 0.05). At the onset of the FSH treatment (Day 0 of the protocol), 1.7 M heifers had greater body condition score (BCS), BW and serum insulin concentrations than 0.7 M heifers (4.1 ± 0.1 vs. 3.0 ± 0.1; 462.5 ± 10.1 vs. 382.7 ± 10.4 kg; and 14.3 ± 1.7 vs. 3.5 ± 0.8 μIU/mL, respectively). The 0.7 M heifers had more follicles ≥6 mm at the time of the last FSH (Day 7; 47.9 ± 6.4 vs. 23.5 ± 4.3 follicles), related to a better follicle superstimulatory response to FSH. Similarly, 0.7 M heifers had more corpora lutea at the time of embryo collection (33.6 ± 1.4 vs. 15.7 ± 0.9) than the 1.7 M heifers, which resulted in greater number of recovered embryos and ova (9.9 ± 0.7 vs. 6.7 ± 0.6) and viable embryos (5.3 ± 0.5 vs. 3.8 ± 0.4), despite having similar proportions of viable embryos (∼62%). A negative correlation between circulating insulin and follicle superstimulatory response to FSH was observed (r = -0.68). Therefore, we conclude that high feed intake, for a long period of time, compromised the superovulatory response and embryo production potential of Bos indicus heifers possibly related to the elevation in circulating insulin.
authors.affiliation: National Water Agency (ANA), Brasília, Federal District, Brazil.
authors.forename: Marcos R
authors.initials: MR
authors.lastname: Mollo
authors.affiliation: Department of Animal Science, ESALQ, University of São Paulo, Piracicaba, São Paulo, Brazil.
authors.forename: Pedro L J
authors.initials: PLJ
authors.lastname: Monteiro
authors.affiliation: Department of Animal Science, ESALQ, University of São Paulo, Piracicaba, São Paulo, Brazil.
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Surjus
authors.affiliation: Rio Verde University, Jataí, Goiás, Brazil.
authors.forename: Aline C
authors.initials: AC
authors.lastname: Martins
authors.affiliation: Embrapa Genetic Resources and Biotechnology, Brasília, Federal District, Brazil.
authors.forename: Alexandre F
authors.initials: AF
authors.lastname: Ramos
authors.affiliation: Department of Animal Science, ESALQ, University of São Paulo, Piracicaba, São Paulo, Brazil.
authors.forename: Gerson B
authors.initials: GB
authors.lastname: Mourão
authors.affiliation: Integral Animal Nutrition, Goiânia, Goiás, Brazil.
authors.forename: Luiz H D
authors.initials: LHD
authors.lastname: Carrijo
authors.affiliation: Alta Genetics Inc, Watertown, WI, USA.
authors.forename: Gláucio
authors.initials: G
authors.lastname: Lopes
authors.affiliation: Geneal Genetics and Animal Biotechnology, Uberaba, Minas Gerais, Brazil.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Rumpf
authors.affiliation: Department of Dairy Science, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Milo C
authors.initials: MC
authors.lastname: Wiltbank
authors.affiliation: Department of Animal Science, ESALQ, University of São Paulo, Piracicaba, São Paulo, Brazil. Electronic address: robertosartori@usp.br.
authors.forename: Roberto
authors.initials: R
authors.lastname: Sartori
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D046149:Embryo Culture Techniques; D005260:Female; D005307:Fertilization in Vitro; D013480:Superovulation; D020858:Tissue and Organ Harvesting
keywords: Bos indicus; Embryo; Feed intake; Insulin; Multiple ovulation