Results of a recent research trial undertaken by Teagasc researchers in Moorepark, Co. Cork, were presented at the Grass-Fed Dairy Conference on Thursday (October 25).
The objective of the study was to compare milk yield (kg) and milk solids yield (kg) from grass-only swards, grass-clover swards and a total mixed ration (TMR) diet.
The trial entailed: a grass-only sward, receiving 250kg/ha of nitrogen; a grass-clover sward (annual clover content of 24%), receiving 250kg/ha of N; and a confinement treatment on a TMR diet. The grazing treatments were stocked at 2.74LU/ha and the work was carried out over two years (2015 and 2016).
Results
As part of the trial, cows were balanced for lactation number and calving date and a number of interesting results were produced.
The researchers found the TMR treatment had significantly greater daily milk yield and milk solids yield compared to the grass-only and grass-clover treatments.
However, no economic analysis has been carried out on the production differences (outlined below) to suggest that the additional production would justify investment in concrete.
Daily milk solids yield from cows on grass-only swards, cows on grass-clover swards and cows fed TMR indoors over two lactations. Graph source: Teagasc
When the grass-clover and grass-only treatments were compared, the grass-clover treatment was found to have significantly greater milk yield and milk solids compared to the grass-only treatment. This was particularly the case from June until the end of lactation.
The study found that clover inclusion in the diet increased cumulative milk yield by 588kg/cow and milk solids yield by 41kg/cow compared to the grass-only treatment.
However, in terms of herbage production, no significant difference was observed between the grass-only (13.84t/ha) and the grass-clover (13.95t/ha) treatments.
Daily and cumulative milk and milk solids yield from cows on grass-only (GO) swards, cows on grass-clover (GC) swards and cows fed TMR indoors over two lactations. Treatments with the same letter in a row are not significantly different to each other. Table source: Teagasc
Conclusions
From the study, the researchers concluded that the feeding system had a significant effect on milk and milk solids yield, with the TMR treatment having the greatest impact on production.
In addition, the inclusion of clover in the sward significantly increased milk and milk solids compared to the grass-only treatment, but clover inclusion did not increase total sward herbage production.