Content^a (g/kg milk) of odd and branched-chain fatty acids (OBCFA) in milk from three breeds of dairy cow over four time points; 5 days in milk (DIM), 95 DIM, 185 DIM, 275 DIM.

<p>Content<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150386#t004fn001" target="_blank">^<u>a</u></a> (g/kg milk) of odd and branched-chain fatty acids (OBCFA) in milk from three breeds of dairy cow over four time points; 5 days in milk (DIM), 95 DIM, 185 DIM, 275 DIM.</p

Milk yield and components of three breeds of dairy cow^a over four time points; 5 days in milk (DIM), 95 DIM, 185 DIM, 275 DIM.

<p>Milk yield and components of three breeds of dairy cow<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150386#t002fn001" target="_blank">^<u>a</u></a> over four time points; 5 days in milk (DIM), 95 DIM, 185 DIM, 275 DIM.</p

Content^a (g/kg milk) of major fatty acids in milk from three breeds of dairy cow over four time points; 5 days in milk (DIM), 95 DIM, 185 DIM, 275 DIM.

<p>Content<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150386#t003fn001" target="_blank">^<u>a</u></a> (g/kg milk) of major fatty acids in milk from three breeds of dairy cow over four time points; 5 days in milk (DIM), 95 DIM, 185 DIM, 275 DIM.</p

Ingredient and chemical composition (mean ± standard deviation) of the pre-partum and post-partum diets.

<p>Ingredient and chemical composition (mean ± standard deviation) of the pre-partum and post-partum diets.</p

Image_2_Alteration of Rumen Bacteria and Protozoa Through Grazing Regime as a Tool to Enhance the Bioactive Fatty Acid Content of Bovine Milk.TIF

<p>Rumen microorganisms are the origin of many bioactive fatty acids (FA) found in ruminant-derived food products. Differences in plant leaf anatomy and chemical composition between cool- and warm-season pastures may alter rumen microorganisms, potentially enhancing the quantity/profile of bioactive FA available for incorporation into milk. The objective of this study was to identify rumen bacteria and protozoa and their cellular FA when cows grazed a warm-season annual, pearl millet (PM), in comparison to a diverse cool-season pasture (CSP). Individual rumen digesta samples were obtained from five Holstein cows in a repeated measures design with 28-day periods. The treatment sequence was PM, CSP, then PM. Microbial DNA was extracted from rumen digesta and sequence reads were produced with Illumina MiSeq. Fatty acids (FA) were identified in rumen bacteria and protozoa using gas-liquid chromatography/mass spectroscopy. Microbial communities shifted in response to grazing regime. Bacteria of the phylum Bacteroidetes were more abundant during PM than CSP (P < 0.05), while protozoa of the genus Eudiplodinium were more abundant during CSP than PM (P < 0.05). Microbial cellular FA profiles differed between treatments. Bacteria and protozoa from cows grazing CSP contained more n-3 FA (P < 0.001) and vaccenic acid (P < 0.01), but lower proportions of branched-chain FA (P < 0.05). Microbial FA correlated with microbial taxa and levels of vaccenic acid, rumenic acid, and α-linolenic acid in milk. In conclusion, grazing regime can potentially be used to alter microbial communities shifting the FA profile of microbial cells, and subsequently, alter the milk FA profile.</p

Image_1_Alteration of Rumen Bacteria and Protozoa Through Grazing Regime as a Tool to Enhance the Bioactive Fatty Acid Content of Bovine Milk.TIF

<p>Rumen microorganisms are the origin of many bioactive fatty acids (FA) found in ruminant-derived food products. Differences in plant leaf anatomy and chemical composition between cool- and warm-season pastures may alter rumen microorganisms, potentially enhancing the quantity/profile of bioactive FA available for incorporation into milk. The objective of this study was to identify rumen bacteria and protozoa and their cellular FA when cows grazed a warm-season annual, pearl millet (PM), in comparison to a diverse cool-season pasture (CSP). Individual rumen digesta samples were obtained from five Holstein cows in a repeated measures design with 28-day periods. The treatment sequence was PM, CSP, then PM. Microbial DNA was extracted from rumen digesta and sequence reads were produced with Illumina MiSeq. Fatty acids (FA) were identified in rumen bacteria and protozoa using gas-liquid chromatography/mass spectroscopy. Microbial communities shifted in response to grazing regime. Bacteria of the phylum Bacteroidetes were more abundant during PM than CSP (P < 0.05), while protozoa of the genus Eudiplodinium were more abundant during CSP than PM (P < 0.05). Microbial cellular FA profiles differed between treatments. Bacteria and protozoa from cows grazing CSP contained more n-3 FA (P < 0.001) and vaccenic acid (P < 0.01), but lower proportions of branched-chain FA (P < 0.05). Microbial FA correlated with microbial taxa and levels of vaccenic acid, rumenic acid, and α-linolenic acid in milk. In conclusion, grazing regime can potentially be used to alter microbial communities shifting the FA profile of microbial cells, and subsequently, alter the milk FA profile.</p