Pre-weaning nutritional management and dry season nutritional supplementation on intake, growth and onset of puberty of improved Zebu heifers

Abstract

Abstract Two succeeding studies on the same heifers were conducted to investigate 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 (experiment 2) of improved Zebu (pure Mpwapwa and Mpwapwa crossbred) heifers. The pre-weaning management systems were: Artificial rearing (R1) — weaning at 75 days of age, grazing with supplementation ad libitum; Restricted suckling (R2) — weaning at 6 months of age, grazing with supplementation ad libitum; Artificial rearing (R3) — weaning at 75 days of age, grazing with no supplementation. Experiment 1 was conducted during 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, 167 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 heifers arranged in a 3 × 3 factorial design, weighing 54–110 kg liveweight and aged 6–7 months were used. The pre-weaning management system and breed had no effect on the daily liveweight gain and final liveweight of the heifers ( p > 0.05). Initial weight influenced the final liveweight ( p p p > 0.05). Supplementation increased daily total dry matter intake (TDMI) ( p p > 0.05). Experiment 2 was conducted during the following wet season for a period of 7 months. The heifers grazed throughout the day with no concentrate supplementation, and were penned individually to have access to mineral licks during the night. They were weighed and blood sampled once a fortnight. The onset of puberty was determined through radioimmunoassay (RIA) of blood plasma progesterone. Pre-weaning management system and breed had no effect on the daily gain and final weight of the heifers ( p > 0.05). Dry season supplementation influenced final weight of the heifers but had no effect on the daily liveweight gain of the heifers ( p > 0.05). Concentrate supplementation 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 and 203 kg as age and weight at onset of puberty, reduced from 2–3 years common in the area of study.