Yield and Reproduction Characteristics of Friesian Cattle Under North African Conditions

Abstract

Analyses of data from 156 dairy herds identified significant sources of variation by region, herd within region, month, and year of calving for milk yield, fat yield, and fat percentage. Friesian cows in Tunisia reached their maximum milk yield between 63 and 84 mo of age. The average milk yield was 4000kg, fat yield was 177kg, and fat percentage was 2.93%. These averages were not adjusted for DIM or age at calving. Differences among the three strains of Holsteins in this study were generally small and non-significant. Friesian cows born and raised in Tunisia tended to have shorter lactations than imported cattle. North American Holsteins tended to have more DIM than European Friesians. Friesians born and raised in Tunisia had the lowest milk yield: about 9% less than North American Holsteins. European Friesians yielded more than cattle developed locally, but they still yielded about 6% less than North American Holsteins. The DIM was considered to be an environmental variable rather than a consequence of low milk yield potential. Cows calving in August yielded 384kg less milk than cows calving in January. Adjustment factors for DIM, age, and month of calving were developed to enhance the use of dairy records.