PREWEANING NUTRITIONAL MANAGEMENT AND DRY SEASON NUTRITIONAL SUPPLEMENTATION ON INTAKE, GROWTH AND ONSET OF PUBERTY OF IMPROVED ZEBU HEIFERS

Two succeeding studies on the same heifers were conducted to investiga te the effects of various methods of pre-weaning management during the wet season and feeding regime on the post-weaning performance during succeeding dry season (experiment 1) and the following wet season (exp eriment 2) of improved Zebu (pure Mpwapwa and Mpwapwa crossbred) heife rs. The pre-weaning management systems were: Artificial rearing (R1) - weaning at 75 days of age, grazing with supplementation ad libitum; R estricted suckling (R2) - weaning at 6 months of age, grazing with sup plementation ad libitum; Artificial rearing (R3) - weaning at 75 days of age, grazing with no supplementation. Experiment 1 was conducted du ring the dry season for 5 months and the feeding regimes were: Feeding ad lib Cenchrus ciliaris hay (T1) with no supplementation (control); supplemented (T2) with 1 kgDM per day of concentrate (13.2 MJ/kgDM, 16 7 g CP/kgDM); supplemented (T3) with 1 kgDM of concentrate per day (13 .0 MJ/kgDM, 202 g CP/kgDM). 14 pure Mpwapwa and 13 Mpwapwa crossbred h eifers arranged in a 3 x 3 factorial design, weighing 54-110 kg livewe ight and aged 6-7 months were used. The pre-weaning management system and breed had no effect on the daily liveweight gain and final livewei ght of the heifers (p > 0.05). Initial weight influenced the final liv eweight (p < 0.05). Supplementation increased the daily liveweight gai n and influenced final liveweight of the heifers (p < 0.05). Initial l iveweight, pre-weaning management system and breed had no effect on dr y matter intake (DMI) of hay (p > 0.05). Supplementation increased dai ly total dry matter intake (TDMI) (p < 0.05), but had no effect on the daily DMI of hay (p > 0.05). Experiment 2 was conducted during the fo llowing wet season for a period of 7 months, The heifers grazed throug hout the day with no concentrate supplementation, and were penned indi vidually to have access to mineral licks during the night. They were w eighed and blood sampled once a fortnight. The onset of puberty was de termined through radioimmunoassay (RIA) of blood plasma progesterone. Pre-weaning management system and breed had no effect on the daily gai n and final weight of the heifers (p > 0.05). Dry season supplementati on influenced final weight of the heifers but had no effect on the dai ly liveweight gain of the heifers (p > 0.05). Concentrate supplementat ion of 1 kgDM per day (13.0 MJ/kgDM, 160-200 g CP/kgDM) during the dry season improved the performance of the Mpwapwa heifers to 19 months a nd 203 kg as age and weight at onset of puberty, reduced from 2-3 year s common in the area of study.