1. Milk yield loss in response to feed restriction is associated with mammary epithelial cell exfoliation in dairy cows
- Author
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Lucile Hervé, Margaux Véron, Marion Boutinaud, Jacques Portanguen, H. Quesnel, Rupert M. Bruckmaier, Jj Gross, Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Elevage [Rennes] (PEGASE), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Veterinary Physiology, Vetsuisse Faculty, Universität Bern [Bern], AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de la Recherche Agronomique (INRA), and AGROCAMPUS OUEST-Institut National de la Recherche Agronomique (INRA)
- Subjects
Hydrocortisone ,Apoptosis ,feed restriction ,immunomagnetisme ,histologie ,Lactation ,dairy cows ,Udder ,Insulin-Like Growth Factor I ,2. Zero hunger ,0303 health sciences ,medicine.diagnostic_test ,[SDV.BA]Life Sciences [q-bio]/Animal biology ,food and beverages ,04 agricultural and veterinary sciences ,Dairying ,medicine.anatomical_structure ,Milk ,vache laitière ,restriction alimentaire ,Female ,mammary epithelial cell ,medicine.drug ,Biology ,Milking ,03 medical and health sciences ,Animal science ,Mammary Glands, Animal ,Biopsy ,Genetics ,medicine ,Animals ,cellule épithéliale mammaire ,Dry matter ,production de lait ,030304 developmental biology ,Cell Proliferation ,Immunomagnetic Separation ,dairy cow ,0402 animal and dairy science ,Epithelial Cells ,exfoliation ,040201 dairy & animal science ,Prolactin ,Diet ,Animal Science and Zoology ,Cattle ,Food Deprivation ,Food Science - Abstract
International audience; In dairy cows, feed restriction is known to decrease milk yield by reducing the number of mammary epithelial cells (MEC) in the udder through a shift in the MEC proliferation-apoptosis balance, by reducing the metabolic activity of MEC, or both. The exfoliation of MEC from the mammary epithelium into milk is another process that may participate in regulating the number of MEC during feed restriction. The aim of the present study was to clarify the mechanisms that underlie the milk yield loss induced by feed restriction. Nineteen Holstein dairy cows producing 40.0 +/- 0.7 kg/d at 77 +/- 5 d in milk were divided into a control group (n = 9) and a feed-restricted group (n = 10). Ad libitum dry matter intake (DMI) was recorded during a pre-experimental period of 2 wk. For 29 d (period 1), cows were fed either 100 (control) or 80% (feedrestricted) of their ad libitum DMI measured during the pre-experimental period. Then, all cows were fed ad libitum for 35 d (period 2). Milk production and DMI were recorded daily. Blood and milk samples were collected once during the pre-experimental period; on d 5, 9, and 27 of period 1; and on d 5, 9, and 30 of period 2. Mammary epithelial cells were purified from milk using an immunomagnetic method to determine the rate of MEC exfoliation. Mammary tissue samples were collected by biopsy at the end of each period to analyze the rates of cell proliferation and apoptosis and the expression of genes involved in synthesizing constituents of milk. Feed restriction decreased milk yield by 3 kg/d but had no effect on rates of proliferation and apoptosis in the mammary tissue or on the expression of genes involved in milk synthesis. The daily MEC exfoliation rate was 65% greater in feed-restricted cows than in control cows. These effects in feed-restricted cows were associated with reduced insulin-like growth factor-1 and cortisol plasma concentrations. When all cows returned to ad libitum feeding, no significant difference on milk yield or MEC exfoliation rate was observed between feed-restricted and control cows, but refeeding increased prolactin release during milking. These results show that the exfoliation process may play a role in regulating the number of MEC in the udders of dairy cows during feed restriction without any carryover effect on their milk production.
- Published
- 2019