title: Effects of protein supplementation frequency on physiological responses associated with reproduction in beef cows.
abstract: The objective of this experiment was to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen nonpregnant, nonlactating beef cows were ranked by age and BW and allocated to 3 groups. Groups were assigned to a 3 × 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal supplementation daily (D), 2) soybean meal supplementation 3 times/week (3WK), and 3) soybean meal supplementation once/week (1WK). Within each period, cows were assigned to an estrus synchronization protocol: 100 μg of GnRH + controlled internal drug release device (CIDR) containing 1.38 g of progesterone (P4) on d 1, 25 mg of PGF2α on d 8, and CIDR removal + 100 μg of GnRH on d 11. Grass-seed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK was supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18 whereas 1WK was supplemented on d 4, 11, and 18. Blood samples were collected from 0 (before) to 72 h after supplementation on d 11 and 18 and analyzed for plasma urea-N (PUN). Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h and analyzed for mRNA expression of carbamoyl phosphate synthetase I (CPS-I; h 28) and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment × hour interaction, P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01) and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P ≤ 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P ≥ 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose, and P4 concentrations, whereas plasma insulin concentrations were greater (P ≤ 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P4 concentrations, which are known to impact reproduction in beef cows.
authors.affiliation: Oregon State University, Eastern Oregon Agricultural Research Center, Burns 97720.
authors.forename: B I
authors.initials: BI
authors.lastname: Cappellozza
authors.affiliation: Oregon State University, Eastern Oregon Agricultural Research Center, Burns 97720 reinaldo.cooke@oregonstate.edu.
authors.forename: R F
authors.initials: RF
authors.lastname: Cooke
authors.affiliation: Oregon State University, Eastern Oregon Agricultural Research Center, Burns 97720.
authors.forename: M M
authors.initials: MM
authors.lastname: Reis
authors.affiliation: Oregon State University, Eastern Oregon Agricultural Research Center, Burns 97720.
authors.forename: R S
authors.initials: RS
authors.lastname: Marques
authors.affiliation: Oregon State University, Eastern Oregon Agricultural Research Center, Burns 97720 Faculdade de Medicina Veterinária e Zootecnia, UNESP - Univ. Estadual Paulista, Programa de Pós-Graduação em Zootecnia, Botucatu, SP, Brazil, 18618-970.
authors.forename: T A
authors.initials: TA
authors.lastname: Guarnieri Filho
authors.affiliation: Department of Animal Science, South Dakota State University, Brookings 57007.
authors.forename: G A
authors.initials: GA
authors.lastname: Perry
authors.affiliation: Nutrition Program, School of Biological and Population Health Sciences, Linus Pauling Institute, Oregon State University, Corvallis 97331.
authors.forename: D B
authors.initials: DB
authors.lastname: Jump
authors.affiliation: Nutrition Program, School of Biological and Population Health Sciences, Linus Pauling Institute, Oregon State University, Corvallis 97331.
authors.forename: K A
authors.initials: KA
authors.lastname: Lytle
authors.affiliation: Oregon State University, Eastern Oregon Agricultural Research Center, Burns 97720.
authors.forename: D W
authors.initials: DW
authors.lastname: Bohnert
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001806:Blood Urea Nitrogen; D002417:Cattle; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D019587:Dietary Supplements; D015237:Dinoprost / Q000494:pharmacology; D004973:Estrus Synchronization / Q000187:drug effects*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007315:Insemination, Artificial / Q000662:veterinary*; D007328:Insulin / Q000097:blood; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012098:Reproduction / Q000502:physiology; D013025:Glycine max
chemical_list: D004044:Dietary Proteins; D007328:Insulin; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D015237:Dinoprost
keywords: beef cows; plasma urea-N; progesterone; protein; supplementation frequency; uterine pH