The grazing system at SPT Tawau to be analysed in this chapter has 5 subunits (or 5 subsystems):
Brahman Cow-calf, Bali (Bosjavanicusd’Alton, 1823)Cow-calf, Droughtmaster Cow-calf, Heifer and
(a) Brahman Cow-calf Unit
The Brahman Cow-calf Unit comprised 11 paddocks. The cattle were divided into 3 or sometimes 4 groups and allocated 3 or sometimes 4 paddocks per group. The total area of the unit in 2014 was 195 ha. Until 2012 the unit operated on 161.1 ha. However, the effective area was enlarged to approximately 175 ha in 2012 and to 195 ha in 2013, with the expansion occurring when the
Droughtmaster Cow-calf Unit was phased out. The main grass species used on this unit were B.
decumbens, P. maximum‘Guinea’, and D. milanjiana‘Jarra’. Soil samples were collected from this unit
and analysed and key soil characteristics were: pH, 4.5±0.0; total N, 0.1±0.1%; available P, 24.2±12.6 ppm; K, 0.1±0.0 meq%; Ca, 1.5±0.3 meq%; and Mg, 0.3±0.3 meq% (see Appendix 5.1 for the chemical tests used). The grazing rotation used for the cattle groups was 28 days (from the first day grazing on the first paddock until returning to the first paddock again). Calves born on this unit remained with the cows until weaning when the calves were >150 kg (Details in Appendix 5.2; including for Bali and Droughtmaster cattle described below). Cattle were weighed once monthly, or sometimes at two or
three month intervals, using a digital scale (TRU–TESTTM HD800). Once weaned, the female calves
were transferred to the Heifer Unit (see below), while the male calves were transferred to the cut-and- carry feedlot (Chapter 4). Once >250 kg liveweight, however, the young bulls were returned to the grazing paddocks (in the Brahman Bull Unit, see below; the reason for not sending the weaned Brahman male calves directly to the Brahman Bull Unit is that they can be killed by older cattle.).
Mating used a “bull-in/bull-out” system, with bulls run with the cows from Feb until April and from August until October, rather than being run with cows year round just as is normally practiced on other farms in Sabah. One characteristic of the system is that cows may have a high energy demand as a result of being pregnant while still feeding a calf. Cows that do not calve regularly are kept in the herd
up to several years (3–5 years), but are eventually culled. The cattle are treated for parasites as required
(both for internal and external parasites). Some of the cows in this unit were imported as heifers from Australia. The imported heifers were 18 months old and averaged 260 kg live weight on arrival. For
2008–2014, the average calving percentage in this unit was 42% (= 100 u calves born ÷ cows to bull),
cows joined with bull), and the cow efficiency was 0.19 (= productivity ÷ cow liveweight). Calving
interval was 19.0r8.1 months. The average calf loss (including Bali and Droughtmaster Cow-calf Units
described below) was 9%, with the causes of loss including: dystocia, bleeding nose (epistaxis), abandonment by the mother, poor milk supply from the mother because of mastitis, accidental death (e.g. fell into a ravine, drowned in a muddy area, snake bite), and attack by stray dogs.
(b) Bali Cow-calf Unit
The Bali Cow-calf Unit is operated on two paddocks of 26.3 ha total area. Both paddocks were planted
with S. sphacelata ‘Kazungula’. However, many remnants of A. compressus and B. decumbens were
found in the paddocks. Soil characteristics for this unit were: pH, 4.8±0.2; total N, 0.1±0.0%; available P, 14.4±10.4 ppm; K, 0.1±0.0 meq%; Ca, 1.4±0.7 meq%; and Mg, 0.7±0.5 meq%. The grazing rotation
was 14 days. A few of the cattle in this unit were Bali crossbred (Brahman u Bali by conventional
mating). The animal management was similar to that on the Brahman Cow-calf Unit, except that the weaned male calves sent to the cut-and-carry feedlot system were later sold once >290 kg liveweight
and not returned to the grazing system. For 2008–2013, the average calving percentage, cow
productivity, and cow efficiency were, respectively, 47%, 77.1, and 0.25 (The values were calculated as
in 5.2.1.1(a) above). Calving interval was 19.5r9.8 months.
(c) Droughtmaster Cow-calf Unit
The Droughtmaster Cow-calf Unit had 38.5 ha total area in three paddocks, but as noted above was phased out from 2008 to 2013 (the breed was phased out by the farm because of the longer calving
interval, i.e., 23.7r11.8 months, compared to the Brahman and Bali and not because of any animal
growth rate issue), and the area had been reduced to 4 ha by 2013. However, the transfer of land to the Brahman Cow-calf Unit happened about a year after reduction in animal numbers (due to delay in repairing and realigning fences) so that in the interim a small number of remaining cattle were grazing the entire 38 ha area. The analysis for this unit is therefore compiled from the historical records before
it was phased out. The main grass species planted on this unit were B. decumbens and S. sphacelata
‘Kazungula’. Soil samples collected from this unit were included with the analyses of those from the Brahman Cow-calf Unit. The grazing rotation used was 28 days but was reduced to 14 days in 2012.
Cow-calf Unit the weaned male calves sent to the cut-and-carry feedlot system were sold once >380 kg liveweight and not returned to the grazing system. Historical reproductive performance was: calving percentage, 46%; cow productivity, 82.9; and cow efficiency, 0.18 (The values were calculated as in 5.2.1.1(a) above).
(d) Heifer Unit
The Heifer Unit is operated on four paddocks of 52.6 ha total area, with B. decumbens and S.
sphacelata ‘Kazungula’ as the main sown grasses. Soil characteristics were: pH, 4.8±0.2; total N,
0.1±0.0%; available P, 9.7±3.5 ppm; K, 0.2±0.2 meq%; Ca, 1.0±0.4 meq%; and Mg, 0.4±0.3 meq%. The grazing rotation used was 28 days. The Brahman, Bali, and Droughtmaster heifers were all farmed in this unit. The heifers were transferred to the Brahman, Bali or Droughtmaster Cow-calf Units once >250 kg liveweight.
(d) Brahman Bull Unit
The Brahman Bull Unit is operated on three paddocks of 43.3 ha total area. All three paddocks are
planted with B. decumbens. Soil characteristics were: pH, 4.6±0.3; total N, 0.1±0.0%; available P,
17.6±5.3 ppm; K, 0.1±0.0 meq%; Ca, 1.6±0.3 meq%; and Mg, 0.3±0.1 meq%. The grazing rotation used was 28 days. The non-breeding bulls were brought in from the cut-and-carry feedlot at >250 kg liveweight. Some of the bulls were imported from Australia at 13 months of age at an average live weight of 350 kg. The number of bulls on the farm was gradually increased from 2008 and 2013, but the effective area was not enlarged to accommodate that change.
5.2.2 Data collection