Feeding tests with glycerol conducted in Estonia

In 2009, two large-scale feeding tests were conducted in Märja test farm in Estonia. The first test looked into the possible usage of glycerol as a glycogenic precursor after the calving period. The second experiment explained to what extent it is possible to replace the barley flour in FRMF with glycerol. The crude glycerol used in the tests came from the Biooil Ltd production plant.

The first test was carried out on 14 dairy cows of Estonian Holstein breed in their first lactation period. The test period began on the fourth day after calving and lasted for up to the 21. day of lactation. The animals were fed according to their required norms and they were given concentrated fodder and silage separately. The experimental group was orally given an additional 500 ml of crude glycerol per day. The animals were fed and milked twice a day. Milk production and feed intake were recorded daily.

The second test was conducted in the principle of 4×4 Latin square on 8 dairy cows of Estonian Holstein breed in their first lactation period. Four of the cows had rumen fistulas. At the beginning of the experiment cows were divided into pairs on the basis of the day of lactation, milk production, body weight and feed intake. One test period was 21 days long, of which 14 days were the pre-period and 7 days the main period. The cows were fed FRMF in four different rations (glycerol content 0kg, 1kg, 2kg and 3kg). In all of them barley flour was replaced with crude glycerol. In addition to measuring the intake of dry matter and the analysis of milk production, the splitting of nutrients was determined by using the in sacco method.

The experiments showed the following:

  • The animals who got crude glycerol, ate more ration fodder during the entire test period (first test) than the animals of the control group because the intake of silage increased. This in turn had a positive effect on milk production, being an average of 1,6 kg bigger in the first three weeks on lactation. Oral administration of crude glycerol had also a positive effect on the milk lactose content.
  • Substituting barley flour with crude glycerol (glycerine, glycerine) in FRMF (second test) increased the intake of ration dry matter and improved the feed efficiency. If the feeds had a similar energy value, the milk production in case of different rations did not differ, but the feeding of crude glycerol increased the protein content in milk. Given the increase in the feed intake, there is great potential in terms of bigger milk production. Feeding crude glycerol did not significantly affect the rumen acidity, but the best result is reached when the quantity of glycerol ration is increased gradually allowing the rumen environment to adapt to the changes.
  • Feeding crude glycerol instead of barley flour as part of FRMF does not affect the splitting of nutrients in silages.