The effect of length of dry period, lactation length and calving interval on subsequent lactation yield

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Siyunyi, Tekulo Samuel
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The University of Zambia
This research was conducted to find out the effects of the length of dry periods (DD), lactation length (DL), season of calving (SC), parity (P) and calving interval (CI) on the subsequent milk yield of the cows in Palabana. Data was collected from Palabana Dairy Training Institute. The data was stretching over a period of ten years (from 1990 to 2001) and was for 60 cows each consisting of a set of data the parameters under study. The data was analysed using MINITAB 14 regression equations and the analysis of variance (ANOVA). From the data collected the following conclusions were made: The average milk yields were 2955.3 Kg. 3540.9 Kg, 3432.4 Kg, 3124.6 Kg and 3137.1 Kg for parities I. 2, 3, 4 and 5 respectively. This was in agreement with what Mwenya and Shandomo found out in 1993. R" indicated that for parity 1, 54% of the milk yield was contributed by CI, DD and the SC. Parity 2 had 62 % contribution from all the parameters. Parity 3 had 39.2% pontribution from CI, DD and SC. Parity 4 had 33% contribution from CI, DD and SC. While for parity 5, 59% contribution came from LL and CI.