Milk yield and composition, nutrition, body conformation traits, body condition scores, fertility and diseases in high-yielding dairy cows - Part 1

Twenty-nine pairs of high-yielding dairy cows (HC; greater than or equal to 45 kg/day reached at least once during lactation) and corresponding contro l cows (CC; with milk yields representing the average yield of the herds) w ere examined on 29 Swiss farms from March 1995 to September 1996. The hypot heses were tested that there are differences in feed intake, body conformat ion traits, body weight (BW), body condition score (BCS), fertility status and disease incidence between HC and CC cows. Cows were studied 2 weeks bef ore and at 5, 9, 13, 17 and 40 weeks post-partum. HC cows produced more ene rgy-corrected milk (ECM) than CC cows (10 670 +/- 321 kg in 293 +/- 5 days and 8385 +/- 283 kg in 294 +/- 4 days, respectively; P less than or equal t o 0.001) and yields in the first 100 days of lactation were greater in HC t han in CC cows (46.2 +/- 1.1 and 36.2 +/- 1.0 kg ECM/day, respectively; P l ess than or equal to 0.001). Concentrate intake was greater (P less than or equal to 0.05) in HC than in CC cows (7.6 +/- 0.5 and 5.7 +/- 0.5 kg/day, respectively) and dry matter intakes (measured in week 5 of lactation over 3 days on six farms) were greater in HC than in CC cows (24.0 +/- 1.1 and 2 0.3 +/- 1.1 kg/day, respectively; P less than or equal to 0.001). HC cows w ere taller than CC cows (wither heights 143.3 +/- 0.8 and 140.1 +/- 0.8 cm, respectively; P less than or equal to 0.001). Although BW in HC cows was g reater than in CC cows throughout the study, differences and decreases of B W during lactation were not significant. BCS at the end of pregnancy and de crements during lactation were similar in HC and CC cows. Fertility paramet ers were similar in HC and CC cows. Incidences of mastitis, claw and feet p roblems, hypocalcemia/downer cow syndrome, ovarian cysts and abortions were similar in HC and CC cows, but there were more indigestion problems in HC than in CC cows.