Publication Title

Annual Milk Yield Index As An Alternative Approach To Measuring Dairy Cow Productivity
Authors: 
M. G. Nassuna-Musoke
Volume: 
4
Year of Publication: 
2009

Publication Abstract

The annual milk yield (AMY) index was used to compare the cow productivity in terms of yield and reproductive ability of Friesians on open grazing (OG) and zero grazing (ZG) smallholdings in the Kampala environment with that of Friesians in the temperate climates. Small farms (n=85) located 12 kilometres from Kampala city centre provided records from 191 cows. A total of 4455 monthly total milk yield records from 345 cow-parities were used to analyse daily milk yield (DMY) and total lactation yields (LMY). Fixed effects of management system, parity, stage of lactation, calendar month and year on DMY were examined with an F-test, and their effects on LMY were tested under the GLM procedure. Comparing least squares means using a t-test, tested differences in subclasses of significant independent variables. AMY was obtained by dividing mean LMY by mean Calving interval (CI) multiplied by 365. The LMY of the Kampala Friesian was 65% but the AMY 52% of the temperate Friesian cow. Mean CI for Kampala and temperate zone Friesians was 464 and 375 days respectively. Postpartum resumption of oestrus was 96 (se = 51), compared to 21 days for the temperate Friesian. Overall AMY was 8.5 and 16 litres/day/year for Kampala and temperate cows respectively. ZG cows showed significantly higher performance than OG cows with AMY of 3397 and 3154 litres (p = 0.0012), LMY of 4171 and 3510 litres (p = 0.0001) and CI of 455 and of 473 days (p=0.09) respectively. The results demonstrated AMY reflects the economic efficiency of the animal better than the LMY. The differences between ZG and OG demonstrate the importance of climatic stress in depressing the productivity of the cows, and leads to the conclusion that the environment depresses production efficiency of Friesian cows in Kampala.