Date: Oct 2004 Author: Brad Granzin
There is an ongoing debate among dairy farmers, nutritionists and researchers around the world about what is the best energy supplement for grazing dairy cows. To date there has been comparatively little research undertaken in Australia examining this topic. This is surprising given that the typical dairy farm can spend more than $20 000 per year on concentrates.
This article reports on some research carried out at Wollongbar Agricultural Institute, where Holstein-Friesian cows were grazed on either ryegrass or kikuyu pasture and were given a grain supplement of either barley or maize.
There have been numerous experiments with feedlot dairy cows comparing how maize and barley grain affect milk production. These studies suggest that the energy available from maize is used more efficiently for milk production than the energy available from barley. This is primarily because the majority of the starch from maize is digested in the intestine, whereas barley starch is predominantly digested in the rumen. A cow can use intestinally digested starch more efficiently for milk production.
The key outcomes from the research are listed below. It should be noted that the milk production data obtained from these studies were from cows in early lactation. (The data are provided in Table 1 and Table 2.)
There were two experiments conducted at Wollongbar comparing maize and barley as energy supplements for grazing Holstein-Friesian cows in early lactation:
In both studies, cows were fed either a rolled barley or a rolled maize based concentrate at either 5 kg or 9 kg per cow per day. Both concentrates had the same energy content. Milk production data from these studies is shown in Table 1.
|Real difference between:|
|5||9||5||9||Treatments||Grain type||Feeding level|
Table 2 describes the economics of these experiments for a base price of 30c per litre (calculated on an average of 4.0% fat and 3.2% protein) and 0.335c per 0.1% plus or minus the difference in either fat % or protein % from this average.
These calculations show an economic advantage of maize over barley at all feeding levels. It shows that based on this pay system you could afford to pay between $28 and $74 more per tonne of maize and still have an economic advantage.
It must be noted, however, that the milk production data from these studies were from cows in early lactation. Whether or not we would see the same changes in milk fat and protein concentrations of cows in mid–late lactation is unknown and requires investigation.
Farmers of course should consider current barley and maize prices, and hence the cost of purchasing grain, versus the return received for each additional litre of milk produced, before deciding on a feeding strategy.
|5 kg/cow/day||9 kg/cow/day|
|Cents difference in returns between grains at same level of feeding||–||+37||–||+35|
|How much more could you afford to pay for maize? ($/tonne)||–||+74||–||+38|
|Cents difference in returns between grains at same level of feeding||–||+28||–||+26|
|How much more could you afford to pay for maize? ($/tonne)||–||+56||–||+28|
These experiments were supported by the Dairy Research and Development Corporation.