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New Research Suggests Calf Diets Need Supplemental Fatty Acids

Posted: June 11, 2009

It appears that linolenic acid is deficient in typical calf diets.

Fatty acid requirements of calves have not been defined because there is limited research in this area. However, typical calf starters are based on corn and soybeans and contain relatively little linolenic acid and also have a high ratio of linoleic to linolenic acid. These are essential fatty acids that calves cannot make. Scientists at Akey Inc. (or North American Animal Nutrition Inc.) have conducted several trials investigating fatty acid levels in milk replacer and calf starter, and they reported the results of two studies in the February issue of the Journal of Dairy Science. Calves were fed flax oil, which is high in linolenic acid, or fish oil, which contains longer chain fatty acids derived from linolenic acid.

Typical calf starters are based on corn and soybeans and contain relatively little linolenic acid and also have a high ratio of linoleic to linolenic acid. These are essential fatty acids that calves cannot make.

In the first trial 48 calves were fed starter containing no flax or fish oil, 0.125% of a calcium salt of flax oil, 0.25% of a calcium salt of flax oil, or 0.25% of a calcium salt of fish oil. Calves received free-choice starter from two to three days of age through 84 days of age and were weaned at 28 days. After weaning starter was combined with 5% chopped grass hay. No effect of fish oil was observed on calf growth or health. Average daily gain from day 0 to 56 and from day 56 to 84 increased as the amount of flax oil in starter increased. Hip width also increased from day 0 to 56 as flax oil increased, indicating that calves were increasing in weight and skeletal parameters.

In trial two, 96 calves were fed starter containing 0%, 0.083%, 0.167%, or 0.25% of a calcium salt of flax oil. Starter was blended with 5% chopped grass hay and fed free-choice. Calves began this study at 59 to 60 days of age and ended at 84 days. In this trial, both average daily gain and feed efficiency increased as the amount of flax oil in starter increased.

In both trials, calves fed the highest level of flax oil consumed approximately twice as much linolenic acid per day as calves fed no flax oil (6.6 and 6.9 grams per day in trials one and two), and calves fed the highest level of flax oil gained 0.16 pounds per day more than those fed no flax oil (between days 56 and 84). The cost of adding the highest rate of flax oil was just $0.46 per calf for the entire 84-day experiment in trial one and $0.14 per calf for the 28-day trial two.

From this research, it appears that linolenic acid is deficient in typical calf diets. In this study, the cost of supplementing linolenic acid was minimal relative to the growth benefit.

Coleen Jones, Research Associate, Jud Heinrichs, Professor of Dairy and Animal Science, Department of Dairy and Animal Science