Effect of walking on roughage intake and milk yield and composition of Montbeliarde and Tarentaise dairy cows

Twenty-eight multiparous cows (14 Tarentaises and 14 Montbeliardes) in mid-lactation were used in a changeover design with two periods. Throughout the trial, animals received a second cut cocksfoot hay ad libitum, complemented with a fixed amount of concentrate adapted to the milk production of each animal. The first day of each of the two 8-day periods, one of the two groups (seven cows of each breed) was subjected to a single walking of 12.8 km. During the following 24 h, walking incurred a drop in the quantities of forage ingested (-1.1 kg dry matter/day, P < 0.01) and in milk yield, which was greater (P < 0.05) in the Montbeliarde (-3.3 kg/day) than in the Tarentaise (-1.7 kg/day) cows. At the same time, fat content increased similarly in both breeds (+6 g/kg, P < 0.01). Protein content increased only in the Montbeliarde cows (+1.1 g/kg, P < 0.1). In both breeds, milli cell counts rose significantly after walking (+600 000 cells/mL, P < 0.01), but no occurrence of clinical mastitis was observed. Walking provoked a rise in body temperature (+0.5 degrees C, P < 0.01) and in nonesterified fatty acids (+1.18 mM/L, P < 0.01) and glucose (+0.08 g/L, P < 0.01) plasma contents.