A Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of Doctor of
Philosophy in Life Sciences and Bioengineering of the Nelson Mandela African Institution
of Science and Technology
Seasonality-driven changes in farmer-led feeding and breeding approaches are increasingly
captured as contributing to fluctuations in milk yield and reproductive performance of dairy
cows in smallholder dairy farms in Eastern Africa. This study aimed to assess the effects of
location, agro-ecology, production systems, breed types and seasonal changes on milk yield and
reproductive performance of dairy cows; and to propose potential modifiable farmer-led
interventions for overcoming fluctuations in dairy production. A cross-sectional household
survey from 400 smallholder dairy farming households in highlands and lowlands of Kenya and
Tanzania, followed by an observational monitoring study for a period of one year, were used to
establish the effects of seasonality on milk yield and reproductive performance. Questionnaire
and Feed Assessment Tool (FEAST) were used to collect data. Descriptive statistics and
regression analysis using multivariate/multinomial analysis of variance (MANOVA) were
employed to display variable seasonal differences in performance. Mean separation was carried
out using least significant difference (LSD) at P ≤ 0.05 significance level. Results revealed that
year round rainfall seasonality and differences in location, agro-ecology, breeds and production
systems, significantly (P < 0.05) resulted into changes in reproductive performance and milk
yield. Mean values for AFS, AFC and CI were higher in the dry season than in wet season (32.34
SEM = 0.90 v‟s 29.14 SEM 0.90 months; 38.05 SEM = 0.61 v‟s 36.23 SEM 0.62 months; and
469.60 SEM = 8.78 v‟s 445.49 SEM 8.94 days), respectively. Wet and dry season variation (%)
in calving interval was +/-6.30%, ranging from +/-5.00-15.00% between breeds within agro ecologies. Similarly, daily milk yield per cow (L) was lower in the dry season than in wet season
(8.44 SEM = 0.27 v‟s 9.01 SEM 0.30). Season variation (%) in daily milk yield, between wet
and dry seasons was +/-6.22%, which was lower for local zebu (+/-3.96%) and highest for
improved breeds (+/-14.50%). There was significant (P < 0.05) year round variation in feeds and
fodder sources (quality and quantity) and usage, with the exception of concentrate feeding. In
vitro culture of crop residues pre-treated with urea and urea plus molasses, and further
comprehensive in vitro culture of maize stover, showed positive effects (P < 0.05) on chemical
and nutritional composition in terms of total gas production (GP), dry matter digestibility
(DMD), crude protein (CP) and metabolizable energy (ME), amongst all other parameters. This
study concludes that iinterventions for increasing farmers‟ experience and knowledge in
overcoming seasonality driven milk fluctuations, must be holistic, in due consideration of
seasonality and environment effects, in order to improve milk yield and reproductive efficiency
sustainably over time. It is recommended that the new knowledge gained with this research can
be incorporated into a holistic model of optimization of cow performance and thereby be one
among other tools for optimizing production economy of smallholder dairy farmers in Eastern
Africa