Effect of Feeding Dry Glycerin to Dairy Cows

An experiment currently in progress is evaluating the effects of feeding dry glycerin to early lactating Holstein dairy cows. Over the years, different nutritional strategies have been evaluated in order to overcome the negative energy balance during early lactation. Some of these strategies include the use of glucose precursors like glycerin and propylene glycol. Glycerin may improve energy supply in early lactation dairy cows. As shown by a few European studies, glycerin might increase energy balance and thus lower the incidence of ketosis resulting in higher dry matter intake and milk yield.

When compared to propylene glycol, glycerin may yield similar results but it has the advantage of lower cost which is expected only to decrease as it is a byproduct of the biodiesel industry and is becoming more available. Biodiesel production generates glycerin of different purities and it is important to have a high purity product (>95 percent) as the energy content decreases as purity goes down and may contain methanol. We assigned mature Holstein dairy cows to two groups of 20 cows each starting the day of calving until 3 weeks into lactation. Cows in one group are provided 250 g/d of dry glycerin top dressed on to the total mixed ration.

Intake and milk yield is recorded daily and individual milk samples collected once a week for the first 3 weeks of lactation. Blood samples are collected approximately 2 h after morning feeding on days 4, 7, 14, and 21 after calving. Cow health, calf birth weight, calving difficulty score, and body condition score are all measured throughout the trial. The study should be completed by early spring.

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Daniel Rico, Undergraduate Student from Bogota, Colombia, Marcela Martinez, Graduate Student, and Gabriella Varga, Professor of Animal Science Dairy and Animal Science Extension