Short Communication: Effect of Timing of Introduction to Pasture Post Calving and Supplementation with <i>Saccharomyces cerevisiae</i> on Milk Fatty Acid Profiles in Early Lactation Dairy Cows

Abstract

There is increased public awareness of the effect of dietary fatty acid (FA) profile on human health. Therefore, when devising nutritional management strategies for dairy cows it is important to evaluate the effects of said strategies on the FA profile of the milk. This experiment investigates the effects of two early PP nutritional management strategies (NM); abrupt introduction to pasture (AP) or a total mixed ration for 21 d followed by a gradual introduction to pasture over 7 d (GP), with (Y) or without (C) live yeast (YS) on milk fatty acid (FA) profile. Forty multiparous dairy cows were assigned to one of four dietary treatments in a two (AP vs. GP) by two (Y vs. C) factorial, randomized block design. The experiment was conducted from d 1 to 70 PP. Pasture, TMR and concentrate samples were taken weekly to assess the chemical and FA composition. Milk yield was recorded daily and individual milk samples were collected weekly to determine milk FA composition. There was no interaction between NM strategy and YS supplementation on milk FA. Similarly, YS supplementation did not affect milk FA profile. However, GP had higher concentrations of C10 (P = 0.04), C12 (P = 0.01), C14 (P = 0.02) and medium chain FA (P = 0.02) vs. AP. Whereas AP had higher concentrations of the FA cis-9, C18:1 (P < 0.01), long chain FA (P = 0.1) and unsaturated FA (P = 0.01) and lower concentrations of saturated FA (P = 0.01) vs. GP. These results suggest that abruptly introducing the early lactation dairy cow to a pasture based diets positively alters the FA composition of the milk produced when compared to the milk from a dairy cow gradually introduced to pasture.