RELATIONSHIPS BETWEEN GROWTH-PARAMETERS I N HEIFERS OF THE CZECH PIEDCATTLE AND THEIR SUBSEQUENT PERFORMANCE

The objective of the study was to analyze relationships between the gr owth stages of heifers and their performance in the Ist lactation. The investigation involved 155 heifers of the Czech Pied breed born on on e farm from April 1988 to September 1992. Estimates of weights at the age of 3, 6, 9, 12, 15 and 18 months were calculated from the weights recorded by weighing during heifer rearing using Richard's function in the form y(t) = Al(1 + Be--kt)(1/m). Average daily weight gains in th e quarterly periods were derived from these estimates. The program GLM SAS Institute Inc. (1988) was used for statistical processing of data . Residual correlations of the characteristics under observation were calculated, eliminating the effect of birth time and heifer breed. The effect of weight and average daily weight gains on Ist lactation perf ormance was also tested by multivariate analysis of variance. Statisti cally highly significant (P < 0.001) residual correlations (r = 0.381 to 0.977) were determined between the weights in all periods of invest igation. The closest relation between the weight at 18 months and the average daily weight gain was observed in the 6th-9th months and/or 9t h-12th months of age (r = 0.866 and/or r = 0.878). In these periods a positive relation to weight gain in all the other periods was observed (r = 0.130 to 0.789 and r = 0.240 to 0.891). Negative correlations of weight until 6 to 9 months and average daily weight gains in the seco nd year of heifer life, as well as the negative correlation of average daily weight gain at 3 to 6 months and weight gains at 12 to 15 month s and 15 to 18 months (r = -0.170; P < 0.05 and r = -0.398; P < 0.001) suggest a slower onset of the growth retardation stage in heifers wit h less intensive growth at the beginning of the period of observation. Correlation analysis did not demonstrate any statistically significan t relations between live weight and milk performance traits. Residual correlations were low and ranged from r = -0.115 to 0.141. Residual co rrelations for the relation between average daily weight gains and per formance traits were also low (r = -0.042 to 0.160). Correlations betw een growth rate at 12 to 18 months of age and the fat and protein prod uction were the only at the level of significance (P = 0.067 to 0.047) . Analysis of variance did not demonstrate any statistically significa nt effects of the observed growth parameters on performance in the Ist lactation in the given conditions except the effect of weight on prot ein percentage at three months of age (P = 0.029).