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This Article Free Via Open Access Full Text Full Text (PDF) All Versions of this Article: jas.2008-1753v1 87/10/3304    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Sullivan, T. M. Articles by Perry, V. E. A. PubMed PubMed Citation Articles by Sullivan, T. M. Articles by Perry, V. E. A.

Dietary protein during gestation affects maternal insulin-like growth factor, insulin-like growth factor binding protein, leptin concentrations, and fetal growth in heifers¹

T. M. Sullivan^*, G. C. Micke^*, N. Perkins, G. B. Martin, C. R. Wallace, K. L. Gatford^#, J. A. Owens^# and V. E. A. Perry^*,2

^* School of Veterinary Science, The University of Queensland, St. Lucia, Queensland 4072, Australia; and Ausvet Services, 30 Plant St., Toowoomba, Queensland 4350, Australia; and UWA Institute of Agriculture, University of Western Australia, Crawley, Western Australia 6009, Australia; and Animal and Veterinary Sciences, University of Maine, Orono 04469; and ^# School of Paediatrics and Reproductive Health, University of Adelaide, South Australia 5005, Australia

² Corresponding author: v.perry{at}uq.edu.au

The influence of supplemental protein during gestation on maternal hormones and fetal growth was determined in composite beef heifers. At AI, 118 heifers were stratified by BW within each composite genotype (BeefX = 1/2 Senepol, 1/4 Brahman, 1/8 Charolais, 1/8 Red Angus and CBX = 1/2 Senepol, 1/4 Brahman, 1/4 Charolais) into 4 treatment groups: high high (HH = 1.4 kg CP/d for first and second trimesters of gestation), high low (HL = 1.4 kg of CP/d for first trimester and 0.4 kg of CP/d for second trimester), low high (lowH = 0.4 kg CP/d for first trimester and 1.4 kg of CP/d and for second trimester), or low low (LL = 0.4 kg CP/d for first and second trimesters). Maternal plasma IGF-I and -II, total IGFBP, and leptin concentrations were determined at 14 d before AI and at d 28, 82, 179, and 271 post-AI (mean gestation length 286 d), and leptin concentrations were also determined at calving. Increased dietary protein increased maternal plasma IGF-I (P < 0.001 on d 28, 82, and 179), IGF-II (P = 0.01 on d 82; P = 0.04 on d 271), and total IGFBP (P = 0.002 on d 82; P = 0.005 on d 179; P = 0.03 on d 271). Maternal plasma IGF-I at d 271 was negatively associated with calf crown-rump length at birth (P = 0.003). BeefX had greater birth weight calves (P = 0.01), greater IGF-II (P < 0.001), increased ratios of IGF-I:total IGFBP (P = 0.008) and IGF–II:total IGFBP (P < 0.001), and reduced total IGFBP compared with CBX (P = 0.02). Increased dietary protein during second trimester increased maternal plasma leptin at calving (P = 0.005). Maternal plasma leptin near term was positively associated with heifer BCS (P = 0.02) and with calf birth weight (P = 0.04), and at calving was positively associated with heifer age at AI (P = 0.02). These findings suggest that maternal dietary protein, age, and genotype influence plasma concentrations of metabolic hormones and fetal growth in Bos indicus-influenced heifers.

Key Words: cattle • crude protein • fetal growth • gestation • insulin-like growth factor • leptin