ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 65 Number 3
Weaning and 18-month weights of Boran, East African Shorthorn Zebu and Sahiwal breeds or crosses in Kenya
Data from 1055 calves at two Kenya Ministry of Agriculture and Livestock Development Research Stations, Kiboko and Bachuma, of Small East African Shorthorn Zebu (Z), Boran (B), Sahiwal (S), B × Z, S × Z, Friesian (F) × B and F × S breedtypes were analysed to identify and quantify factors affecting weaning and 18-month weights. Breedtype, sex, year, season and birth month within season, weaning age, total rainfall and age of dam affected weaning weight (P < 0.01), but station had no effect. Rankings of breedtypes at Kiboko for average weaning weight were F × S (heaviest), F × B, S, B, S × Z, B × Z and Z. Steers averaged 8 kg heaviest than heifers. Calves born July-December were 12 kg heavier than those born January-June. Partial linear regressions of weaning weight on total rainfall were 0.20 ± 0.09-0.48 ± 0.14 kg mm-1, and for weaning weight on age were 0.26 ± 0.06-0.39 ± 0.98 kg day-1. Heavier calves at weaning were from 7- and 8-yr-old dams, and lightest calves were from 2-4-yr-old dams. Year, breed type, sex, station, month of birth and breedtype × station interaction affected 18-month weights (P < 0.01). Breedtype rankings, high to low, for 18-month weight at Kiboko were the same as for weaning weights. The lightest breedtype at 18-month age was S and the heaviest F × S at Bachuma, and S was heaviest and F × B lightest at Kiboko. At 1 8 months steers were 10 kg heavier than heifers and Bachuma calves were 12 kg heavier than Kiboko calves. Calves bom in January and September were the heaviest at 18 months and those born in April and August were the lightest.
Keywords: Weaning weight; 18-month weight; Boran; East African Shorthorn Zebu; Sahiwal; Crosses; Kenya