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.
Highlights
In recent years consumers have become increasingly aware of the potential health benefits from consuming dairy products rich in polyunsaturated fatty acids (PUFA), those in the n-3 fatty acid (FA) group and the conjugated linoleic acid (CLA) isomer cis-9 trans-11 C18:3 to produce linoleic (C18):2 (Ruminic acid, RA) [1]
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
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
Summary
In recent years consumers have become increasingly aware of the potential health benefits from consuming dairy products rich in polyunsaturated fatty acids (PUFA), those in the n-3 (omega-3) fatty acid (FA) group and the conjugated linoleic acid (CLA) isomer cis-9 trans-11 C18:2 (Ruminic acid, RA) [1]. Short Communication: Effect of Timing of Introduction to Pasture Post Calving and Supplementation with Saccharomyces cerevisiae on Milk Fatty Acid Profiles in Early Lactation Dairy Cows zation [8], altering the FA profile in milk. Nutritional management (NM) strategies such as gradual introduction to pasture (GP) may ameliorate the negative effects of abrupt dietary changes [9]. Live yeast supplementation has been reported to alter rumen pH and volatile fatty acid (VFA) concentrations [11, 12]. The hypothesis of the current study is that abrupt turn out to pasture and supplementation with live yeast may improve the concentrations of CLA in the milk of early lactation dairy cows when compared to milk from dairy cows gradually introduced to pasture
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