Abstract
The purpose of the study was to identify a cost-effective supplementation regimen to rear replacement heifers on transitional Cymbopogon-Themeda veld. A total of 120 Drakensberger heifers aged 6 - 7 months were randomly allocated to three supplementary treatment groups from 2011 - 2014. A three-phase supplementation programme was used while the production year was divided into three periods, namely summer (wet season) (approximately mid-December to March), winter (early dry season) (April to July), and late winter (late dry season) (August to approximately mid-December). The late winter treatments consisted of three levels of supplemental crude protein (CP), a percentage of protein derived from non-protein nitrogen (NPN) and metabolizable energy (ME), namely T1: 306 g CP/kg (47.4% NPN) + ME 7.4 MJ/kg; T2: 329 g CP/kg (70.72% NPN) + ME 6.89 MJ/kg; and T3: 475 g CP/kg (95.86% NPN) + ME 2.4 MJ/kg. In summer, T1 was supplemented with 164 g CP/kg (7% NPN) + ME 9 MJ/kg + 13 g P/kg; T2 with Voermol Superfos with 150 g CP/kg (13.6% NPN), ME 0 MJ/kg, and 50 g P/kg; T3: 0 g CP/kg, ME 0 MJ/kg, and 60 g P/kg. The traits were nutrient intake, supplement cost, mean bodyweight, weight gains/losses and mean BCS. The study concluded that feeding replacement heifers to traditional bodyweight increased development costs without improving production sufficiently. Veld that is in good condition together with a mineral (60 g P/kg) supplement in the wet season and a protein and mineral supplement (96% NPN) in the dry season gives the highest economic return.
 Keywords: beef heifers, post wean, supplementation
Highlights
An adequate level of feed is necessary for good performance of heifers in their first and subsequent production cycles as cows (Wiltbank et al, 1984; Scholtz et al, 1991), whether they are mated at 12 - 14 months or at two years old
The returns must at least compensate for the costs incurred in feeding supplements (De Waal, 1990)
It is logical to assume that most factors that are associated with reproductive performance in cattle are influenced almost exclusively by management (Patterson et al, 2002)
Summary
An adequate level of feed is necessary for good performance of heifers in their first and subsequent production cycles as cows (Wiltbank et al, 1984; Scholtz et al, 1991), whether they are mated at 12 - 14 months or at two years old. Most mechanisms of fertility, which influence calving and subsequent reproductive performance, are not highly heritable. It is logical to assume that most factors that are associated with reproductive performance in cattle are influenced almost exclusively by management (Patterson et al, 2002). The management of replacement heifers in the post-weaning to pre-breeding period influences the times at which puberty, pregnancy, and parturition occur (Patterson et al, 2002)
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