Forced walking prepartum for dairy cows of different ages

Fifty-three 2-yr-old Holstein heifers and 63 cows from 3 to 7 yr old were exercised 5 days/wk for 8 wk before calving. Three treatments were: 1) control (no forced exercise); 2) walk 1.6 km/day; and 3) walk 8.0 km/day. Exercise was at 4.0 km/h in a circular lane with a motor-driven gate. Daily feed intake and weekly body weights were recorded during the prepartum period and 50 days postpartum. Daily milk production and semimonthly milk composition were recorded for the complete lactation. Exercise did not affect feed intake during the prepartum period. Weight gain was reduced during the dry period, more for older than for young cows, and particularly less gain for the longer distance. There was no benefit to production or feed efficiency from exercise for any age of cows. Production of protein and solids not fat was higher for combined ages of cows on the shorter than the longer distance. Protein percentage in milk for the lactation was higher for exercised than for control cows; solids-not-fat percentage in milk was higher for exercise for shorter than for longer distance; and fat percentage in milk was not affected by exercise. Number of services per conception and number of days open were less for exercised cows.