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Animal-Level Factors Affecting Ovarian Function in Bos indicus Heifers Treated to Synchronize Ovulation with Intravaginal Progesterone-Releasing Devices and Oestradiol Benzoate

Butler, S. A. A. and Phillips, N. J. and Boe-Hansen, G. B. and Bo, G. A. and Burns, B. M. and Dawson, K. and McGowan, M. R. (2012) Animal-Level Factors Affecting Ovarian Function in Bos indicus Heifers Treated to Synchronize Ovulation with Intravaginal Progesterone-Releasing Devices and Oestradiol Benzoate. Reproduction in Domestic Animals, 47 (3). pp. 463-471. ISSN 0936-6768

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Article Link(s): http://dx.doi.org/10.1111/j.1439-0531.2011.01905.x

Abstract

The primary objective of this study was to investigate the impact of animal-level factors including energy balance and environmental/management stress, on the ovarian function of Bos indicus heifers treated to synchronize ovulation. Two-year-old Brahman (BN) (n = 30) and BN-cross (n = 34) heifers were randomly allocated to three intravaginal progesterone-releasing device (IPRD) treatment groups: (i) standard-dose IPRD [Cue-Mate (R) (CM) 1.56 g; n = 17]; (ii) half-dose IPRD [0.78 g progesterone (P4); CM 0.78 g; n = 15]; (iii) half-dose IPRD + 300 IU equine chorionic gonadotrophin at IPRD removal (CM 0.78 g + G; n = 14); (iv) and a control group, 2x PGF2a [500 mu g prostaglandin F2a (PGF2a)] on Day -16 and -2 (n = 18). Intravaginal progesterone-releasing device-treated heifers received 250 mu g PGF2a at IPRD insertion (Day -10) and IPRD removal (Day -2) and 1 mg oestradiol benzoate on Day -10 and -1. Heifers were managed in a small feedlot and fed a defined ration. Ovarian function was evaluated by ultrasonography and plasma P4 throughout the synchronized and return cycles. Energy balance was evaluated using plasma insulin-like growth factor 1 (IGF-I) and glucose concentrations. The impact of environmental stressors was evaluated using plasma cortisol concentration. Heifers that had normal ovarian function had significantly higher IGF-I concentrations at commencement of the experiment (p = 0.008) and significantly higher plasma glucose concentrations at Day -2 (p = 0.040) and Day 4 (p = 0.043), than heifers with abnormal ovarian function. There was no difference between the mean pre-ovulatory cortisol concentrations of heifers that ovulated or did not ovulate. However, heifers that ovulated had higher cortisol concentrations at Day 4 (p = 0.056) and 6 (p = 0.026) after ovulation than heifers that did not ovulate.

Item Type:Article
Business groups:Animal Science
Additional Information:ISI Document Delivery No.: 924TU Times Cited: 0 Cited Reference Count: 54 Butler, S. A. A. Phillips, N. J. Boe-Hansen, G. B. Bo, G. A. Burns, B. M. Dawson, K. McGowan, M. R. Wiley-blackwell Hoboken
Keywords:tropical beef genotypes growth-factor-i luteinizing-hormone reproductive-performance glucose availability brahman heifers artificial-insemination follicular development northern australia metabolic hormones
Subjects:Animal culture > Breeding and breeds
Animal culture > Cattle > Meat production
Deposited On:10 Apr 2014 02:15
Last Modified:10 Apr 2014 02:15

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