| dc.description.abstract | This thesis describes an investigation into reproductive performance of cows and
heifers on smallholder dairy farms in Kiambu District, Kenya. The objectives of the study
were to describe reproductive management, to estimate herd reproductive parameters and
to investigate associations between the reproductive parameters and general management,
nutrition and housing variables measured on the farm.
The study was conducted on 90 smallholder dairy farms. A two stage cluster
sampling process was used to select si2Cof fourteen dairy co-operative societies marketing
milk in the district followed by the a simple random sampling of fifteen farms actively
producing milk from each dairy co-operative membership list. Response rate among
eligible farms was 98%. The selected farms were visited monthly from July 1991 to June
1992.
The farm was the primary unit of interest, and consequently survey questions and
analysis were designed to assess farm characteristics thought to have a biological
association with reproductive performance. Individual animal examination was also
performed.
Last calving dates, oestrus dates, breeding dates and pregnancy diagnosis results
and calving dates were used to calcula~ecalving to first oestrus interval, first oestrus to
first service interval, calving to first service interval and intercalving interval for cows.
Birth dates, first oestrus dates, first breeding dates, pregnancy diagnosis results and
calving dates were used to calculate age at first oestrus, age at first service and age at
first calving for heifers.
A long estimated average calving interval of 685 (+ /- 231) days was due in part
to a long estimated average calving to first service interval of 316 (+ /- 215) days. One
reason for the late initiation of breeding seemed to be unobserved oestrus as evidenced
by average calving to first oestrus of 279 (+/- 213) days. Another reason was that
farmers didn't have precise policies on when to initiate first breeding post-partum.
Increased herd calving interval was associated with: the absence of a bull in the
herd, a long voluntary waiting period of more than 120 days, a long calving to first
oestrus interval, a long first oestrus to first breeding interval and farms that practised zero
grazing. Reproductive conditions encountered in cows expressed as rates were abortion
(0.09), dystocia (0.08), metritis (0.04), retained placenta (0.12), stillbirth (0.10), repeat
breeding (0.08), milk fever (0.01) and deformed calves (0.03). The associations between
the various reproductive conditions for example dystocia and stillbirth or metritis and
retained placenta could not be established given their relatively infrequent occurrence.
Reproductive performance in heifers was poor. Average age at first calving was
40 (+ /- 7) months. Buying feeds on credit was the only farm factor associated with age
at first calving. This reduced the average age at first calving by 5 months. Reproductive
conditions in heifers were rare as only abortion (0.37) and retained placenta (0.11) were
reported.
From this study it can be concluded that both cows and heifers in the smallholder
dairy farms in Kiambu district have poorer reproductive performance compared to well
managed farms in the temperate regions. The poor cow performance is mainly attributed
to poor oestrus detection which is worsened by housing and nutrition conditions on zerograzing
units and lack of farm policy ~n when cows should be bred post-partum. Poor
heifer reproductive performance is mainly due to poor feeding slowing down growth and
delaying puberty which subsequently led to an older average age at first calving. | en |
