title: Effects of nutrient restriction on mammary cell turnover and mammary gland remodeling in lactating dairy cows.
abstract: The aim of this study was to investigate the effects of a severe nutrient restriction on mammary tissue morphology and remodeling, mammary epithelial cell (MEC) turnover and activity, and hormonal status in lactating dairy cows. We used 16 Holstein × Normande crossbred dairy cows, divided into 2 groups submitted to different feeding levels (basal and restricted) from 2 wk before calving to wk 11 postpartum. Restricted-diet cows had lower 11-wk average daily milk yield from calving to slaughter than did basal-diet cows (20.5 vs. 33.5 kg/d). Feed restriction decreased milk fat, protein, and lactose yields. Restriction also led to lower plasma insulin-like growth factor 1 and higher growth hormone concentrations. Restricted-diet cows had lighter mammary glands than did basal-diet cows. The total amount of DNA in the mammary gland and the size of the mammary acini were smaller in the restricted-diet group. Feed restriction had no significant effect on MEC proliferation at the time of slaughter but led to a higher level of apoptosis in the mammary gland. Gelatin zymography highlighted remodeling of the mammary extracellular matrix in restricted-diet cows. Udders from restricted-diet cows showed lower transcript expression of α-lactalbumin and kappa-casein. In conclusion, nutrient restriction resulted in lower milk yield in lactating dairy cows, partly due to modulation of MEC activity and a lower number of mammary cells. An association was found between feed restriction-induced changes in the growth hormone-insulin-like growth factor-1 axis and mammary epithelial cell dynamics.
authors.affiliation: INRA UMR 1080 Dairy Production, Rennes, France. Frederic.Dessauge@rennes.inra.fr
authors.forename: F
authors.initials: F
authors.lastname: Dessauge
authors.forename: V
authors.initials: V
authors.lastname: Lollivier
authors.forename: B
authors.initials: B
authors.lastname: Ponchon
authors.forename: R
authors.initials: R
authors.lastname: Bruckmaier
authors.forename: L
authors.initials: L
authors.lastname: Finot
authors.forename: S
authors.initials: S
authors.lastname: Wiart
authors.forename: E
authors.initials: E
authors.lastname: Cutullic
authors.forename: C
authors.initials: C
authors.lastname: Disenhaus
authors.forename: S
authors.initials: S
authors.lastname: Barbey
authors.forename: M
authors.initials: M
authors.lastname: Boutinaud
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle; D049109:Cell Proliferation; D004247:DNA / Q000032:analysis; D005223:Fats / Q000032:analysis; D005260:Female; D005508:Food Deprivation / Q000502:physiology; D007774:Lactation / Q000378:metabolism / Q000502:physiology; D007785:Lactose; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D008894:Milk Proteins / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary
chemical_list: D005223:Fats; D008894:Milk Proteins; D004247:DNA; D007785:Lactose