title: Effect of extreme walking conditions for dairy cows on milk yield, chemical composition, and somatic cell count.
abstract: Thirty-two cows (16 Montbeliardes and 16 Tarentaises) in midlactation were used in an experiment utilizing a 2 x 2 factorial arrangement of treatments. Throughout the trial, cows received first-cutting cocksfoot hay for ad libitum intake supplemented with a fixed amount of concentrate that was individually adapted to the milk yield of each cow. During a 23-d experimental period, one group of cows walked 9.6 km/d; the other group of cows remained in the barn. Cows that walked daily ate less hay (-1.3 and -2.1 kg/d of dry matter for Tarentaise and Montbeliarde cows, respectively) and yielded less milk (-1.7 and -2.5 kg/d for Tarentaise and Montbeliarde cows, respectively) than did cows that did not walk daily. A residual effect of walking on milk yield was observed during the 10 d following the experimental period. For both breeds, fat content and, to a lesser extent, protein content were higher (+6.4 and +1.0 g/kg, respectively) for cows that walked. Somatic cell count was also higher for cows that walked (+115,000 cells/ml). This difference was more marked in cows that were initially infected by a minor or major pathogen (+185,000 cells/ml) than in uninfected cows (+47,000 cells/ml) and on the 1st d of walking when walking was linked to increases in pH, bovine serum albumin, and immunoglobulin G1 contents of milk (+0.08 unit, +0.16 g/L, and +0.19 g/L, respectively). Throughout the experimental period, walking induced a rise in body temperature (+1 degree C) and in plasma nonesterified fatty acids (+0.63 mM/L). On the 1st d of walking, plasma glucose, lactic acid, and cortisol contents were significantly higher for cows that walked (+0.25 g/L, +0.64 g/L, and +28.8 ng/ml, respectively).
authors.affiliation: Institute National de la Recherche Agronomique, Laboratoire Adaptation des Herbivores aux Milieux, Saint Genès Champanelle, France.
authors.forename: J B
authors.initials: JB
authors.lastname: Coulon
authors.forename: P
authors.initials: P
authors.lastname: Pradel
authors.forename: T
authors.initials: T
authors.lastname: Cochard
authors.forename: B
authors.initials: B
authors.lastname: Poutrel
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D002452:Cell Count; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005684:Gait; D006724:Hoof and Claw / Q000033:anatomy & histology; D006854:Hydrocortisone / Q000097:blood; D007774:Lactation / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood; D007785:Lactose / Q000032:analysis; D008055:Lipids / Q000032:analysis; D008892:Milk / Q000737:chemistry* / Q000166:cytology*; D008894:Milk Proteins / Q000032:analysis; D016138:Walking / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D008055:Lipids; D008894:Milk Proteins; D019344:Lactic Acid; D007785:Lactose; D006854:Hydrocortisone