Assessing The Reproductive Performance of a Tanzanian Dairy Herd: The Importance of Proper Record Keeping

Abstract

Before attempting to evaluate the fertility of a dairy herd, it is necessary to have accurate reproductive data of all cows. A retrospective longitudinal study was conducted to assess the reproductive performance by analysing records of cows in one conveniently selected dairy herd in Tanzania. The records covered the period between February 1989 and June 1993. The cows in this herd were of Ayrshire and Friesian breeds. Both natural service and AI were utilized for breeding. The average interval (mean ±SD) from calving to first service, first service to conception and calving to conception intervals were 94.85 ± 42.88, 31.8±55.1 and 121.69 ± 60 .65 days, respectively. The conception rate to first service was 60. l %. The overall pregnancy rate in the herd over the study period was not determined due to missing records or variation in the interval from first service to confirmation of pregnancy.  Friesian (n=24) and Ayrshire (n= 17) cows had an average gestation lengths of 275.8±4.8 and 277.1 ±4.0 days, respectively. The average calving interval in the herd was 407.0 ± 66.0 days. The data set had several recording errors. Under recording of events was also common. This paper recommends using the results of the study as a basis of discussion with the farm management team to set targets for several reproductive parameters compare the targets to the current situation and when necessary implement intervention strategies to improve the reproductive performance in the herd. Attainment of the set targets should benefit the farm by optimizing the number of replacement heifers available and milk production per lifetime of individual cows in the herd.