caa a22 4500 388060263 CHVBK 20180307125118.0 cr unu---uuuuu 161130e199812 xx s 000 0 eng 10.1017/S1357729800032811 doi S1357729800032811 pii (NATIONALLICENCE)cambridge-10.1017/S1357729800032811 Modelling the effect of the stage of pregnancy on milk composition [Elektronische Daten] The effect of pregnancy on the fat and protein contents of milk was studied on a 414-lactation sample. One hundred and forty-nine lactations of non-pregnant cows managed under identical conditions served as controls. The difference between individual fat or protein contents of each pregnant animal and the mean corresponding values in controls was computed weekly from the week of conception. The effect of pregnancy on fat and protein concentrations began to be significant from the 20th week of pregnancy, regardless of the week of conception. It was higher in the Friesian breed than in Holstein or Montbeliarde cows. In Holstein and Montbeliarde cows, the effect of pregnancy was higher in high producing multiparous cows (+2·8 and +2·9 g/kg for fat and protein concentrations, respectively, at the 29th pregnancy week) than in primiparous or low producing multiparous cows (+2·0 and +1·4 g/kg, for fat and protein concentration, respectively). In each of these three lactation groups (Friesian, high producing multiparous Holstein and Montbeliarde cows, other Holstein and Montbeliarde cows) the following linear model was fitted, where Y is the difference between fat or protein concentration of pregnant and non pregnant cows at a given stage (week), Pw is the pregnancy week, and a and b are parameters. This increase in milk fat and protein concentrations in late pregnancy cannot compensate the concomitant decrease in milk yield, so that fat and protein yield decreased in the same manner as milk yield during pregnancy (-77 glday and -68 glday at the 29th week of pregnancy, for fat and protein yield, respectively). Copyright © British Society of Animal Science 1998 dairy cows nationallicence mathematical models nationallicence milk composition nationallicence pregnancy nationallicence Coulon J. B. INRA, Laboratoire Adaptation des Herbivores aux Milieux, Theix, 63122 Saint-Genès Champanelle, France Pérochon L. INRA, Unité d'Ecopathologie, Theix, 63122 Saint-Genès Champanelle, France Animal Science Cambridge University Press 67/3(1998-12), 413-419 1357-7298 67:3<413 1998 67 ASC https://doi.org/10.1017/S1357729800032811 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S1357729800032811 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Coulon J. B. INRA, Laboratoire Adaptation des Herbivores aux Milieux, Theix, 63122 Saint-Genès Champanelle, France NATIONALLICENCE 700 1- Pérochon L. INRA, Unité d'Ecopathologie, Theix, 63122 Saint-Genès Champanelle, France NATIONALLICENCE 773 0- Animal Science Cambridge University Press 67/3(1998-12), 413-419 1357-7298 67:3<413 1998 67 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence SWISSBIB 387582924 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge