Over the past 15 years, 30 different research trials have been conducted that examine the impact of supplemental fat on reproductive performance of beef and dairy cattle. Fats (or lipids) have been fed before and after calving and during the breeding season. Research on feeding supplemental fat has resulted in varied and inconsistent results as it relates to reproductive efficiency including positive, negative, and no apparent effect.

Several different fat sources have been studied. Plant oils have thus far shown to have the greatest impact on reproduction. Some of the more common sources of plant oils include: sunflower, safflower, whole cottonseed, rice hulls and soybeans. In addition, animal tallow, calcium salts, and fishmeal have also been evaluated.

Dr. Rick Funston, University of Nebraska beef specialist, reviewed the research pertaining to this topic. His conclusions about added fat in cow and heifer diets suggested that some of the improvements reported may be due to the added energy from the fat source. He suggests that until these relationships are better understood, producers are advised to strive for low cost and balanced rations. IF a source of supplemental fat can be added with little or no change in the ration cost, it would be advisable to add it to the ration. Adding fat would be most likely to have a benefit on reproduction with young, marginally thin, growing cows in a year where limited nutrients are available. In other words, two and three year old cows (in a body condition score of 4 or 5) with low quality and/or quantity of roughage available, are most likely to get a boost from adding whole soybeans, whole cottonseeds, safflower, or sunflowers to their diet.

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