title: Effects of intramammary infusions of casein hydrolysate, ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid, and lactose at drying-off on mammary gland involution.
abstract: The transition from the lactation to the dry period in dairy cows is a period of high risk for acquiring new intramammary infections. This risk is reduced when involution of mammary glands is completed. Consequently, strategies that accelerate the involution process after drying-off could reduce the incidence of mastitis. The objective of this study was to assess the effect of 3 different treatments on mammary gland involution. Each quarter of 8 Holstein cows in late lactation was randomly assigned at drying-off to an intramammary infusion of casein hydrolysate (CNH; 70 mg), ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA; 5.7 g), lactose (5.1g), or saline 0.9% (control) solutions. Milk samples were collected on the last 2 d before and 1, 3, 5, 7, 10, and 14 d after the last milking for determining concentrations of mammary gland involution markers. Lactoferrin, somatic cell counts (SCC), BSA, and Na(+) concentrations, as well as matrix metalloproteinase-2 and matrix metalloproteinase-9 activities gradually increased in mammary secretions during the first 2 wk following the last milking, whereas milk citrate and K(+) concentrations decreased. As involution advanced, the Na(+):K(+) ratio increased, whereas the citrate:lactoferrin ratio decreased. Compared with mammary secretions from control quarters, mammary secretions of quarters infused with CNH had higher SCC on d 1, 3, 5, and 7, and greater BSA concentrations on d 1, 3, and 5. Similarly, the CNH treatment induced a faster increase in lactoferrin concentrations, which were greater than in milk from control quarters on d 3, 5, and 7 after drying-off. Milk citrate concentrations were unaffected by CNH but the citrate:lactoferrin ratio was lower in CNH-treated quarters on d 3 and 5 than in control quarters. Moreover, CNH treatment hastened the increase in Na(+) concentration and in the Na(+):K(+) ratio on d 1. Infusion of CNH also led to an increase in proteolytic activities, with greater matrix metalloproteinase 9 activities on d 1 and 3. The EGTA infusion increased SCC above that of control quarters on d 1 and 3 but it had no effect on the other parameters. Lactose infusion had no effect on any of the involution markers. In this study, intramammary infusions of CNH were the most efficient treatment to accelerate mammary gland involution, suggesting a potential role of CNH as a local milk secretion inhibitor during milk stasis.
authors.affiliation: Department of Animal Science, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada H9X 3V9.
authors.forename: B
authors.initials: B
authors.lastname: Ponchon
authors.affiliation: Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8.
authors.forename: P
authors.initials: P
authors.lastname: Lacasse
authors.affiliation: Agricultural Research Organization, the Volcani Center, Institute of Animal Science, PO Box 6, Bet Dagan, 50250 Israel.
authors.forename: N
authors.initials: N
authors.lastname: Silanikove
authors.affiliation: Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8.
authors.forename: S
authors.initials: S
authors.lastname: Ollier
authors.affiliation: Department of Animal Science, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada H9X 3V9. Electronic address: xin.zhao@mcgill.ca.
authors.forename: X
authors.initials: X
authors.lastname: Zhao
mesh_terms: D000818:Animals; D065096:Calcium Chelating Agents / Q000494:pharmacology*; D002364:Caseins / Q000494:pharmacology*; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D004533:Egtazic Acid / Q000494:pharmacology*; D005260:Female; D055104:Infusions, Subcutaneous / Q000662:veterinary; D007785:Lactose / Q000494:pharmacology*; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D008892:Milk / Q000737:chemistry* / Q000187:drug effects; D011897:Random Allocation
chemical_list: D065096:Calcium Chelating Agents; D002364:Caseins; D004533:Egtazic Acid; D007785:Lactose
keywords: casein hydrolysate; dairy cow; mammary gland involution