Seasonal changes in nutritional status and reproductive performance of Zebu cows kept under a traditional agro-pastoral system in Tanzania
Tropical Animal Health and Production
Department of Veterinary Surgery and Theriogenology, Faculty of Veterinary Medicine, Sokoine University of Agriculture, Morogoro, Tanzania; Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway
The objectives of this study were to assess changes in nutritional status/body condition score, percentage pregnancy and calving rate in Zebu cows and to establish the relationship between body condition score loss and postpartum interval to resumption of ovarian activity. A total of 198 cows and postpubertal heifers of the Tanzanian Shorthorn Zebu kept under a traditional management system were randomly selected from 200 smallholder herds. Factors investigated during bi-weekly visits include body condition score (BCS), heart-girth circumference, milk yield and reproductive status of the animals, pregnancy/non-pregnancy and cyclicity/non-cyclicity. Local weather conditions and dates of occurrence of other reproductive events such as calving were also recorded. Calvings occurred all year round but with a strong seasonal distribution characterized by annual peaks observed between April and July. The annual calving pattern was closely related to rainfall, with peak precipitation occurring a few months before peak calving. The overall percentage pregnancy varied from 30% to 50% throughout the year. Postpartum cows exhibited minimum mean BCS and heart-girth circumference 12-14 weeks after calving, and cows with BCS loss >1 point exhibited the longest time interval from calving to onset of ovarian activity. © 2006 Springer Science + Business Media B.V.
rain; animal; animal food; article; body constitution; cattle; estrus cycle; female; nutritional status; physiology; pregnancy; pregnancy rate; puerperium; reproduction; season; Tanzania; time; Animal Nutrition Physiology; Animals; Body Constitution; Cattle; Estrous Cycle; Female; Nutritional Status; Postpartum Period; Pregnancy; Pregnancy Rate; Rain; Reproduction; Seasons; Tanzania; Time Factors; Animalia; Bos indicus