title: Effect of time at pasture and herbage intake on profile of volatile organic compounds of dairy cow milk.
abstract: Volatile organic compounds (VOCs) in milk were investigated as quantitative markers of herbage intake (HI) at pasture. Eight Holstein cows were fed indoors with concentrate and conserved forages (grass silage, corn silage and hay) (NG), then were divided into three treatments according to the duration of access to pasture: 4 h (G4), 8 h (G8), and 20 h (G20) per day. The HIs were 4.3, 8.6, and 13.0 kg dry matter/day for the G4, G8 and G20 treatments, respectively. Milk from cows was sampled and analyzed VOCs by the steam distillation-extraction method and gas chromatography-mass spectrometry (GC-MS). From the intensity of the GC peak area, the levels of 1-phytene (3,7,11,15-tetramethyl-1-hexadecene) and 2-phytene (3,7,11,15-tetramethyl-2-hexadecene) were lowest in NG treatment and markedly increased with grazing time at pasture. With simple regression analysis on the HI to each diterpenoid, a strong correlation was found between the intensity of 1-phytene in the milk and the HI (r = 0.807, P < 0.001). 1-phytene content in milk could be useful as a quantitative marker of the HI of grazing cows.
authors.affiliation: NARO Hokkaido Agricultural Research Center, Sapporo, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: NARO Hokkaido Agricultural Research Center, Sapporo, Japan.
authors.forename: Sadaki
authors.initials: S
authors.lastname: Asakuma
authors.affiliation: NARO Institute of Livestock and Grassland Science, Nasushiobara, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Miyaji
authors.affiliation: NARO Institute of Livestock and Grassland Science, Nasushiobara, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Akiyama
mesh_terms: D000475:Alkenes / Q000032:analysis; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D060434:Herbivory / Q000502:physiology*; D008892:Milk / Q000737:chemistry*; D012044:Regression Analysis; D013997:Time Factors; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: C000613415:3,7,11,15-tetramethyl-1-hexadecene; D000475:Alkenes; D055549:Volatile Organic Compounds
keywords: 1-phytene; grazing time; herbage intake; milk; volatile organic compounds