| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Division of Nutrition and Physiology, Institute of Animal Genetics, Nutrition and Housing, Vetsuisse Faculty, University of Berne, CH-3012 Berne, Switzerland
2 Department of Dairy and Animal Science, Penn State University, University Park 16802
3 Institute of Physiology, Biochemistry and Animal Hygiene, University of Bonn, D-53115 Bonn, Germany
4 Institute of Nutritional Science, University of Postdam, D-14558 Potsdam, Germany
Corresponding author: J. W. Blum; e-mail: juerg.blum{at}itz.unibe.ch.
Studies in vitro show important interactions among vitamin A, lactoferrin, and insulin-like growth factor (IGF) binding proteins (IGFBP) and, thus, the IGF system. As a consequence, mammary gland epithelial cell proliferation and apoptosis during the bovine dry period and potential milk yield may be affected. We have studied effects of feeding vitamin A (550,000 IU/ d) that exceed daily requirements about 8-fold for up to 2 mo to dairy cows during the dry period on concentrations of retinol and its metabolites in plasma and milk, milk lactoferrin, plasma and milk IGF-I and IGFBP-3, lactoferrin and IGF-I mRNA levels in mammary gland tissue, mammary gland apoptosis, and 100-d milk yield in the ensuing lactation. In the group supplemented with vitamin A, the peripartal decrease of plasma retinol was delayed and attenuated, and colostral retinol plus retinylester concentration was enhanced, but colostral ß-carotene concentration decreased. The retinoic acid isomer 9,13-dicis retinoic acid that coeluted with 13-cis retinoic acid, was the predominant circulating retinoic acid and was higher in GrA than the control group. Plasma IGFBP-3 concentrations were positively correlated with plasma retinol concentrations (r = 0.51), but there were no group differences. Numbers of apoptotic epithelial cells in mammary epithelium were higher at drying off and parturition than in the middle of the dry period, coinciding with high concentrations of IGF-I and lactoferrin in mammary secretions. At parturition, numbers of apoptotic cells in mammary gland biopsies in cows supplemented with vitamin A were higher than in control cows. In conclusion, supplementation of dairy cows during the dry period with high amounts of vitamin A did not significantly modify concentrations of lactoferrin, IGFBP-3, and IGF-I in plasma and in mammary secretions, but slightly decreased energy-corrected 100-d milk yield and milk fat yield, possibly because of enhanced apoptic rates of mammary cells.
Key Words: retinoid • lactoferrin • insulin-like growth factor • mammary gland
Abbreviation key: AP = absorbable protein of the gut, ECM = energy-corrected milk, GH = growth hormone, IGFBP = insulin-like growth factor binding-protein, Lf = lactoferrin, RA = retinoic acid, atRA = all-trans retinoic acid, 9-cis RA = 9-cis retinoic acid, 9,13-dicisRA = 9,13-dicis retinoic acid, 13-cisRA = 13-cis retinoic acid, TUNEL = terminal deoxynucleotidyl transferase (TdT)-mediated X-dUTP nick end labeling
This article has been cited by other articles:
|
|
 |
|
  H. Soyeurt, F. G. Colinet, V. M.-R. Arnould, P. Dardenne, C. Bertozzi, R. Renaville, D. Portetelle, and N. Gengler Genetic Variability of Lactoferrin Content Estimated by Mid-Infrared Spectrometry in Bovine Milk J Dairy Sci, September 1, 2007; 90(9): 4443 - 4450. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
