title: Seasonal changes in nutritional status and reproductive performance of Zebu cows kept under a traditional agro-pastoral system in Tanzania.
abstract: 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/nonpregnancy 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.
authors.affiliation: Department of Veterinary Surgery and Theriogenology, Faculty of Veterinary Medicine, Sokoine University of Agriculture, Morogoro, Tanzania. nkanuya@yahoo.com
authors.forename: N L
authors.initials: NL
authors.lastname: Kanuya
authors.forename: M K
authors.initials: MK
authors.lastname: Matiko
authors.forename: R
authors.initials: R
authors.lastname: Nkya
authors.forename: S B P
authors.initials: SB
authors.lastname: Bittegeko
authors.forename: M N
authors.initials: MN
authors.lastname: Mgasa
authors.forename: O
authors.initials: O
authors.lastname: Reksen
authors.forename: E
authors.initials: E
authors.lastname: Ropstad
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001824:Body Constitution / Q000502:physiology; D002417:Cattle / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D009752:Nutritional Status; D049590:Postpartum Period; D011247:Pregnancy; D018873:Pregnancy Rate; D011891:Rain; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D013636:Tanzania; D013997:Time Factors