Throughout my more than 30 years of studying fat feeding and lipid metabolism in ruminant species, the major emphasis was consistently on sources and feeding rates, but little attention was directed at fat quality.

Why are fat supplements fed? Because in early lactation, cows cannot eat enough to meet their increasing milk production energy requirements. Thus, cows go into negative energy balance. This is an issue for especially the first one-third of a lactation. And, this negative energy balance is more pronounced and for a longer period of time for cows beyond their first lactation. Consequently, fat supplements are used to increase energy density of the ration. But, if a fat supplement decreases dry matter intake (DMI), the benefit of using it is decreased.

In a previous article, I noted that high-palmitic-fatty-acid (greater than 80%) supplements most often decrease dry matter intake (DMI). And, since many studies with that type supplement have been done with midlactation cows over a short term (21 days), it raises the question as to what would be the response in early lactation cows?