Research Article Open Access

Effect of Exposure to Various Durations of Light on Serum Insulin-Like Growth Factor-I in Prepubertal Holstein Heifers

L.J. Spicer1, B.A. Buchanan2, L.T. Chapin2 and H.A. Tucker2
  • 1 Oklahoma State University, United States
  • 2 Michigan State University, United States

Abstract

Our objective was to determine if prolonged exposure to various durations of light (i.e., photoperiod) would affect serum IGF-I concentrations in heifers. Thus, 16 Holstein heifers, 2 to 4 mo of age, were exposed during a 5-wk pretreatment period to 12 h of cool-white fluorescent light (L) at an intensity of 1200 lux and 12 h of dark (D). At 5 wk, photoperiods were adjusted to 24 L: 0 D (24 L), 20 L: 4 d (20 L), 16 L: 8 D (16 L) or 8 L: 16 D (8 L) per 24 h (n=4 heifers per photoperiod treatment). Blood was sampled at 5 wk and monthly for 4 mo. During each sampling period, blood was collected at 16-h intervals for 48 h and serum IGF-I was determined by RIA. Photoperiod treatment, month of experiment and their interactions affected serum IGF-I concentrations. Averaged over months, concentrations of serum IGF-I was greatest in heifers on 16 L; heifers on 20 L had IGF-I concentrations similar to 8 L, 16 L and 24 L and heifers on 24 L had concentrations similar to that of heifers on 8 L. Heifers in all treatment groups exhibited an increase in serum IGF-I concentration during the 4 mo of treatment. Heifers on 16 L and 20 L exhibited the greatest difference in serum IGF-I concentrations compared with 8L heifers after 3 mo of treatment. In conclusion, 16 L increases concentrations of serum IGF-I above that seen for heifers treated with 8 L or 24 L.

American Journal of Animal and Veterinary Sciences
Volume 2 No. 2, 2007, 42-45

DOI: https://doi.org/10.3844/ajavsp.2007.42.45

Submitted On: 3 August 2007 Published On: 30 December 2007

How to Cite: Spicer, L., Buchanan, B., Chapin, L. & Tucker, H. (2007). Effect of Exposure to Various Durations of Light on Serum Insulin-Like Growth Factor-I in Prepubertal Holstein Heifers. American Journal of Animal and Veterinary Sciences, 2(2), 42-45. https://doi.org/10.3844/ajavsp.2007.42.45

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Keywords

  • Photoperiod
  • heifers
  • growth factor
  • prepubertal