Abstract
Animal performance and carcass quality of Holstein steers, which were grazed on a farm to 5-12 months age before fattening periods (Grazing herd: G herd), were compared with those which were fattened using only a conventional system (Control herd: C herd). The G herds, replicated three times during 3years (G1, G2 and G3 herds), consisted of 34-39 Holstein steers (Average body weight 243kg/head). Grazing of G herds was conducted intensively using timothy (Phleum pratense L.) and perennial ryegrass (Loliume perenne L.) swards through the raising period. Then the G herds were fattened about 12 mo. Thereby, total feeding periods of G herds were 545 days. Control herds were two (18 heads and 21 heads: C1 and C2 herd), which were introduced into the farm at the same time as G3; the average body weight of C herds was 263kg/head. C herds were fattened without grazing for about 18 mo. The average feeding period of the C herd was 536 days. Feeding stuff through the fattening period in G and C herds consisted of formula feed (TDN: 71.3%, DCP: 11.4%), food manufacturers' by-product (TDN: 94.8%, DCP: 7.7%) and cane-top. Average body weights at the end of fattening in G and C herds were 805kg/heads and 835kg/head, respectively. Average daily gain (DG) of G herd through the grazing period (0.93kg/day) was lower than that of the C herd through the same period (1.01kg/day). However, DG of the fattening period in the G herd was higher than that of the C herd. Therefore, the DG of whole feeding period in the G herd was similar to that of the C herd (1.04kg/day and 1.06kg/head, respectively). Average carcass weights in G and C herds were 446kg and 474kg. The percentages of carcass over grading 3 of Japanese beef carcass grading standards in G and C herds were 58% and 59%, respectively. Moreover, fewer condemned viscus cows were in the G herd (3/39 heads) than in C herd (9/36 heads).
