Abstract
Out of Holstein heifers entrusted to Yamaguchi Prefectural Raising Farm, 579 heifers that had been nursed and were transferred to the raising and management farm were used to analyse changes in body weight with time so as to determine the effects of the month of transfer to the raising farm on their growth. (1) Although the weight at 7 months of age, immediately before the transfer to raising farm, showed no significant difference by the month of transfer, the weight at 20 months of age showed significant difference (P<0.01). In other words, the growth during the raising period was observed to vary depending upon the month of transfer. (2) The months of transfer were classified into the following 3 seasonal patterns according to the difference in growth. Spring-Summer pattern (SS) Transferred in May, June, July and August. Spring-Autumm Pattern (SA) Transferred in April, September and October. Winter-Spring Pattern (WS) Transferred in January, February, March, November and December. (3) The weight gains during the investigation period showed significant differeces (P<0.05) among 3 seasonal patterns with SS showing the greatest gain followed by SA and WS. The factors influencing the development of seasonal patterns most were the season and the age thereat. The heifers being at higher ages (month) in spring (April and May) were found to show greater growth. The age, however, was found to give little influence on the seasonal patterns stages of 7 to 20 months. (4) The greater growth of SS was found to be attributable to compensatory growth, i.e., faster growth after wintering at the beginning of the second grazing season.
