Nutritional response: In Figure 2 we can show how these nutritional responses affect the number of finishing days taken for a 24kg liveweight (LW) weaned lamb to reach a target slaughter weight of 42kg LW, or 17.5kg carcaseweight (CW).
For example, on the forage herb chicory LW targets are met in nearly a third of the time taken on old pasture, or Scenario A in Table 1 (55 versus 144 days).
Increased carrying capacity: Figure 2 also provides estimates of what each forage’s carrying capacity (stocking rate, SR) potential is.
Chicory can deliver an equivalent continuous SR of 20 lambs/ha compared with old pasture at 11/ha, while lucerne is even higher at 22 lambs/ha. This response is then combined with the nutritional performance (LWG) for each forage option.
Number of finishing cycles a season: Using the number of days needed to reach target slaughter weight Figure 2 also accounts for the number of “finishing cycles” that could be achieved in a 150-day “finishing season” (November-April), say under a lamb trading policy. The high LWG forages of chicory and lucerne allow 2.5 and 2.6 respectively finishing cycles of lambs a season compared with 1.0 cycle on the old pasture.
Estimated gross revenue: When these three factors are combined (Figure 2) and a conservative value of $2.05/kg CW is applied, the result is a two to four-fold increase in gross revenue a hectare from the different forage types relative to the old pasture representing zero pasture renewal (Scenario A).
These higher productivity forage species can have other positive effects on the overall farm livestock enterprise by providing:
- Higher quality feed for growing out replacements before weaning
- An option to increase the performance of lactating hoggets
- A reduction in competition for autumn feed between finishing and capital stock
- A build-up of pasture covers before winter resulting in increased ewe nutrition at lambing.
While the gross revenue data in Figure 2 represents the upper end of what is possible in an intensively managed lamb finishing system (Scenario C, Table 1), it is hoped that this analysis will inspire meat-producing farmers at all levels to be more discriminating when selecting forage species for their livestock enterprises. For those farmers not engaged in pasture renewal (Scenario A, Table 1) perhaps these results may tempt them into starting a regular pasture renovation programme.
- Reference: K. Sanderson, K. Dustow (2012). 2011 Analysis of the value of pasture to the New Zealand Economy. Business and Economic Research Ltd, Wellington. BERL ref #5132.
Simon Moloney is a consulting forage agronomist in Tauranga.
