Effect of a high-palmitic acid fat supplement on milk production in Icelandic dairy cows fed grass silage-based diet

Thirty-seven dairy cows of the Icelandic breed were used in a change-over design experiment. The aim was to analyse the effects of moderate addition of high-palmitic acid (C16:0) fat supplement to a grass silage-based diet. There were three experimental treatments: a treatment with the fat supplement as powder (FAPOW); a treatment with the fat supplement in pelleted concentrate (FAPEL); and a control treatment (CONTROL). Milk protein content was significantly lower, and there was a tendency (p<0.10) toward a higher milk fat content in the fat treatments. This resulted in significantly higher milk fat:protein ratio in the fat treatments compared to the control (FAPOW 1.21 and FAPEL 1.20; CONTROL 1.15). A significant reduction in the ratio of casein in milk protein due to fat addition explains the reduction in milk protein. The concentration of free fatty acids in milk was higher in the fat treatments, especially FAPEL. The ratio of C16:0 in total fatty acids was increased by the fat treatments.