fatty acids

Bijeenkomst: EGF2015
Auteur: Santiago C., Jiménez-Calderón J.D., González A., Vicente F. and Martínez-Fernández A.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
The oceanic climate conditions of Asturias (Spain) are favourable for grass and pasture production. However, the use of concentrates in dairy-cow diets has increased in the last decades. The aim was to study the differences in milk composition in the four feeding systems identified in the North of Spain through the monitoring of 16 dairy farms. The criteria to describe feeding systems were: grazing (G) and nongrazing. Moreover, three subgroups were identified within ‘non-grazing’ in terms of the percentage of the usable agricultural area (UAA) designated to maize culture: less than 20% (20M), about 50% (50M) and more than 75% (75M) of UAA. Four dairy farms were selected by their feeding system. Feed and milk were sampled and analysed in summer, autumn and winter of 2014. The results show that the protein, lactose and solids-non-fat in milk were higher (P

Bijeenkomst: EGF2015
Auteur: Elgersma A., Søegaard K. and Jensen S.K.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
Fresh herbage is an important natural source of protein, fibre, fatty acids (FA) and vitamins in ruminant diets and it is desirable for farmers that they minimise losses. Thus the concentrations of vitamins and FA in herbages during the growing season as well as their fate after cutting are of interest. A study was conducted in Denmark in which a red clover (Trifolium pratense) – perennial ryegrass (Lolium perenne) sward was mown eight times during the crop growing season. Swaths were subjected to three wilting strategies, and sampled at six time intervals after cutting. Dry matter content and concentrations of α-tocopherol, β-carotene and FA were determined. Fatty acid and α-tocopherol concentrations were highest in October, followed by May, and lowest in summer. Total FA and vitamin concentrations showed a significant overall decline from freshly cut to 29 h-wilted forage. Weather conditions and swath management practices had significant effects on the drying rate of cut forage. The magnitude and rates of decline of concentrations of vitamins and FA during the wilting process were not affected by swath management or herbage drying rates. Choice of harvest date and wilting duration could be used as management tools to optimise concentrations of vitamins and FA in forage.

Bijeenkomst: EGF2015
Auteur: Resch-Zafra C., Pereira-Crespo S., Flores-Calvete G., Dagnac T., Gónzalez L., Agruña M.J., Fernández-Lorenzo B. and Veiga M.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
Sixty farms located in the Galicia region (NW Spain) were sampled four times during 2012 and samples of ration ingredients and bulk-tank milk were taken with the objective of studying the relationships between dairy cow ration and the fatty acid (FA) composition of the milk. Diets were grouped into five clusters based on ration ingredients and significant differences among clusters were observed for saturated, polyunsaturated, omega-3 and conjugated linoleic fatty acids, as well as for the omega6- omega3 ratio. In general, milk from grazing extensive systems and from intensive systems based on silage and concentrates supplemented with extruded linseed showed the highest contents of human-health FA. The ability of FA-based discriminant functions for assigning farm tank milk samples to a particular diet was deemed as not satisfactory.