Lactose in blood plasma and the ability of dairy cows to tolerate once-daily milking in terms of milk loss and milk recovery.

Abstract : This experiment described the variability among cows with the aim of studying the ability of dairy cows to tolerate once-daily milking (ODM) in terms of milk losses and milk recoveries observed when cows are switched from twice- to once-daily milking and then back to twice-daily milking (TDM). It also aimed to investigate whether or not lactose in blood plasma, which indicates the mammary epithelium permeability, is correlated with milk losses and recoveries and, consequently, a potential candidate assessor of dairy cow tolerance to ODM. The study used 86 crossbred dairy cows (Holstein × Normande) split into 5 groups over 2 yr. The trial consisted of 3 successive periods: a 1-wk control period of TDM, then 3 wk of ODM, followed by 2 wk of TDM. Blood samples were collected 1 to 1.5h before the morning milking and 5 to 6h after milking on d -3, 0, 1, 3, 7, 21, 23, and 28, where d 0 is the last d of the control period. Milk losses measured as kilograms per day were higher in cows with highest control-period milk yields (r=-0.66). When expressed in relative terms (%), milk losses were weakly correlated with the control-period milk yield (r=-0.22). When switched back to TDM, cows recovered only 47% of the milk lost. Milk recovery (kg/d) was weakly correlated with control milk yield (r=0.34) and not correlated with ODM milk yield. Milk recovery was correlated with milk yield losses: the higher the milk yield losses (kg/d or %), the higher the milk recovery (kg/d; r=-0.59 and -0.52, respectively). Rate of milk recovery expressed as the quantity of milk recovered per kilogram of milk lost, was not correlated with milk loss expressed as a percentage. This means that to be considered well-adapted to ODM scheduling, a cow must be well adapted to milk loss, and be well adapted to milk recovery. Blood plasma lactose concentration (log(10)-transformed data) was not correlated with milk production levels in either control, ODM, or back-to-TDM periods. It was poorly correlated with milk loss but was positively correlated with milk recovery (kg/d) and rate of milk recovery. We conclude that blood plasma lactose needs to be coupled with other indicators for evaluating dairy cow tolerance to ODM.
Type de document :
Article dans une revue
Journal of Dairy Science, American Dairy Science Association, 2011, 94 (7), pp.3446-54. 〈10.3168/jds.2010-4081〉
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Soumis le : vendredi 7 septembre 2012 - 15:31:14
Dernière modification le : samedi 11 novembre 2017 - 01:10:36

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Jocelyne Flament, Y. Gallard, H. Larroque. Lactose in blood plasma and the ability of dairy cows to tolerate once-daily milking in terms of milk loss and milk recovery.. Journal of Dairy Science, American Dairy Science Association, 2011, 94 (7), pp.3446-54. 〈10.3168/jds.2010-4081〉. 〈hal-00729291〉

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