The Effect of the Quantitative Difference in Nutrition during Rearing on the Growth and Reproduction of Female Japanese Black Cattle : I. Growth and reproduction during raising period

The purpose of this investigation was to find out how the quantitative difference in nutrition for the calf would come out on the lifetime performance of the matured beef cow. During the grazing period (the first year), the heifers were divided into two groups. High-nutrition heifers (H) were fed 1.5kg of concentrates every day and low-nutrition ones (L) were fed no concentrate. In the winter feeding period, they were divided into the following three groups according to TDN intake which were classified on the basis of Japanese feeding standards (1970). H group was continued to give high-nutrition (110%) and this group was named HH group. On the other hand, L group was divided into two groups, the heifers which were given high-nutrition (110%) were named LH group, and heifers which were given low nutrition (90%) were LL group. In the second year, all heifers of every group were grazed on improved pastures with no concentrates. The results obtained from about 9 months old to the first calving time were as follows. 1) H group showed more DM and TDN intake than L group during the graging period, but chiefly, this difference was observed from the beginning up to the second month of grazing. Then in re-grazing period (the second year) feed intake of LL group was much greater than that of HH group. Besides, TDN intake of LL group during the re-grazing period, expressed as the percentage of the requirement for the growing female beef cattle in the Revised Edition of Japanese Feeding Standard, was significantly larger than that during the grazing in the first year. 2) Growth of H group in grazing period (the first year) was significantly faster (p<0.05) than that of L group. Only in winter, the growth of LH group had a tendency to be superior to those of HH and LL groups. Although the growth of LL group was considerably slow in this period, there was a remarkable compensatory growth during the regrazing period. 3) The dialy gains during the grazing period indicated significant multiple correlation with intake of TDN and DCP in the first year (r=0.761, p<0.01). 4) Ages at the first insemination of HH, LH and LL groups were 16.0, 16.6 and 18.6 months, respectively. Corresponding figures for conception were 17.4, 17.8 and 21.2 months. In LL group, four of seven heifers had reproductive disturbance in winter. The first insemination and conception among LL group generally took much time than other two groups. From the facts described above, the level of nutrient intake imposed during early life has a pronounced effect on the state of growth and reproduction.