J Dairy Sci. 2017 Apr 20. pii: S0022-0302(17)30337-5. doi: 10.3168/jds.2016-12424. [Epub ahead of print]
- 1
- Instituto
de Investigación en Ciencias de la Alimentación (CSIC-UAM), Universidad
Autónoma de Madrid, Nicolás Cabrera 9, 28049 Madrid, Spain.
- 2
- Departamento de Producción Animal, Universidad de Córdoba, Ctra. Madrid-Cádiz km 396, 14071 Córdoba, Spain.
- 3
- Departamento
de Producción Animal, Universidad de Córdoba, Ctra. Madrid-Cádiz km
396, 14071 Córdoba, Spain. Electronic address: pa1martm@uco.es.
Abstract
Trans-10,cis-15
18:2 has been recently detected and characterized in digestive contents
and meat and adipose tissue of ruminants, but its presence in milk and dairy
products is hardly known. The aim of this study was to quantify
trans-10,cis-15 18:2 in milk fat, better understand its metabolic
origin, and help to elucidate the mechanisms of rumen biohydrogenation
when the diet composition might affect ruminal environment. To address
these objectives, 16 dairy goats were allocated to 2 simultaneous experiments (2 groups of goats
and 2 treatments in each experiment). Experimental treatments consisted
of basal diets with the same forage-to-concentrate ratio (33/67) and 2
starch-to-nonforage neutral detergent fiber (NDF) ratios (0.8 and 3.1),
which were supplemented or not with 30 g/d of linseed oil for 25 d in a
crossover design. Trans-10,cis-15 18:2 contents in milk fat were
determined by gas chromatography fitted with an extremely polar
capillary column (SLB-IL111). Levels of trans-10,cis-15 18:2 in
individual milk fat samples ranged from 0 to 0.2% of total fatty acids,
and its content in milk fat increased 8 fold due to linseed oil
supplementation, substantiating the predominant role of α-linolenic acid
in its formation. The trans-10,cis-15 18:2 levels in milk fat were
similar in both experiments, despite the fact starch-to-nonforage NDF
ratio of their respective basal diets greatly differed. In conclusion,
trans-10,cis-15 18:2 was clearly related to linseed oil supplementation,
and its increase in milk fat was comparable when the basal diets were
rich in either nonforage NDF or starch.
Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
KEYWORDS:
fatty acid; linseed oil; milk fat; α-linolenic acid
