The 2023-24 dairy season was originally intended as the first year of a three-year farm systems comparison incorporating the proposed off-paddock infrastructure into one of the farmlets.
The initial design used an unbalanced 2x2 factorial, with system intensity (standard (Std) vs lower impact (LI)) and wintering type (fodder beet vs silage/baleage) comprising the two factors. The design was unbalanced due to the needs of the standard system, in which it was proposed that cows would be wintered on pasture silage in the off-paddock infrastructure while the LI system cows would be wintered on baleage (LI Baleage) in pasture paddocks within the milking platform area.
A change in funding for the infrastructure build resulted in the build being suspended however the farmlets continued to be implemented as planned, with the exception that the proposed Std Infrastructure farmlet became the Std Baleage farmlet (Table 1).
Table 1: Key physical parameters for the actual farm systems implemented at SDH.
While only being conducted for one season, the farmlet study still provided valuable learning, despite results being observational with no statistical analysis and only representing one season.
Baleage wintering:
Supplement quality is critical in systems where conserved feed makes up a significant proportion or all the winter diet. Baleage farmlets did achieve herd average pre-calving body condition score (BCS) targets but with a wider range in BCS and a higher proportion of individual animals not reaching their target.
Testing of supplement quality is essential for successful wintering outcomes in systems reliant on high intakes of conserved feed.
An 18 T DM baleage/ha ‘yield’ (80 bales per hectare) the wintering paddocks at SDH did not consistently provide better conditions for cattle compared to crop paddocks and the paddocks had to be fully regrassed at the end of the winter.
Increasing pre-graze mass to 2800 kg DM/ha did improve the ground conditions during grazing but there were still significant periods during the winter when cows were standing on bare soils with very little soil armouring.
Farm systems with baleage wintering:
Managing pasture quality during lactation in lower stocking rate systems wintering on baleage required significantly more mechanical intervention (post graze topping or conservation) than the equivalent system wintering on fodder beet.
A lower stocking rate did not result in increased per cow production (Table 2) due to losses in pasture quality resulting from delays with harvesting surplus pasture. Timely decision making and conservation management is key to achieving good pasture quality and milk production outcomes.
Lower stocking rates do provide an opportunity to be more self-contained for winter baleage compared with higher stocked systems but still rely on purchased supplement for wintering given a 100% baleage diet.
Optimising fodder beet wintering:
By removing cows from fodder beet 28 days before their expected calving date we encountered less metabolic issues at calving than had previously been experienced with cows wintered on fodder beet and transitioned straight from beet into the springer mob.
A higher peak milk production was achieved from the optimised fodder beet wintering regime compared with those wintered on baleage and was similar to that measured from cows wintered on kale in previous seasons.
While the proposed three-year farmlet study could not be completed due to funding changes, valuable lessons regarding paddock-based wintering were gained from the revised one-year farm systems study.
Table 2: Summary of physical performance of the SDH farmlets for the 2023-24 season
