Smallholder dairy farming in the Chikwaka communal land, Zimbabwe: birth, death and demographic trends

A study of mortality, morbidity and productivity of cattle on smallholder d airy farms was conducted in Chikwaka communal land, Zimbabwe. We estimated the frequency and determinants of mortality in DDP cattle and explored demo graphic trends. Using Cox proportional-hazards modelling (with the farm as a random effect), the animal-level variables associated with mortality were age, sex and breed. Calf mortality was 35% of calves within the first year of life. This was nearly five-times higher than adult mortality (relative risk (RR) 4.73, 95% CI 2.12, 10.6). Females had lower mortality than males (RR = 0.25, 95% CI 0.11, 0.56). After adjusting for the confounding effects of age, Jersey breeding was associated with higher mortality (RR = 2.89, 9 5% CI 1.16, 7.22) whereas Red Dane breeding was associated with lower morta lity (RR = 0.27, 95% CI 0.11, 0.69). Farms with a higher ratio of non-DDP:D DP cattle had higher mortality in their DDP cattle. Leslie-matrix models si mulated population growth and showed that (at the current levels of mortali ty and fertility) the population would double in approximately 10 years. (C ) 2001 Elsevier Science B.V. All rights reserved.