1 research outputs found
Changes in milk fatty acid profile and animal performance in response to fish oil supplementation, alone or in combination with sunflower oil, in dairy ewes
12 páginas, 4 figuras, 4 tablas.Ruminant diet supplementation with sunflower oil (SO) and fish oil (FO) has been
reported as a good strategy for enhancing some milk fat compounds, such as conjugated
linoleic acid (CLA) and omega-3 polyunsaturated fatty acids (PUFA) in dairy cows, but
no information is available regarding dairy sheep. In this work, ewe diet was
supplemented with FO, alone or in combination with SO, with the aim of improving
milk nutritional value and evaluating its effect on animal performance. Sixty-four Assaf
ewes in mid-lactation, fed a high-concentrate diet, were distributed in 8 lots of 8 animals
each and assigned to 4 treatments (2 lots per treatment): no-lipid supplementation
(Control), or supplementation with 20 g SO/kg (SO), 10 g FO/kg (FO), or 20 g SO plus
10 g FO/kg (SOFO). Milk production and composition, including a complete fatty acid
profile, were analysed on days 0, 3, 7, 14, 21, and 28 on treatments. FO supplementation
tended to reduce DM intake in comparison with the Control treatment (-15%), and its
use in combination with SO (SOFO) resulted in a significant decrease in milk yield as
well (-13%). All lipid supplements reduced milk protein content, and FO also reduced
milk fat content, by up to 21% alone (FO) and 27% in combination with SO (SOFO).
Although the mechanisms involved in FO-induced milk fat depression are not wellestablished
yet, the observed increase in some milk trans-FA that are putative inhibitors
of milk fat synthesis, such as trans-9 cis-11 CLA, and the almost 3-fold decrease in
C18:0 (consistent with the theory of reduced milk fat fluidity) may be involved. When
compared with the Control, lipid supplementation remarkably improved the milk
content of rumenic acid (cis-9 trans-11 CLA; up to 4-fold increases with SO and SOFO
diets), whereas FO-containing diets also increased milk omega-3 PUFA, mainly
docosahexanoic acid (DHA, with mean contents of 0.29 and 0.38% of total fatty acids
for SOFO and FO, respectively), and reduced the omega-6/omega-3 FA ratio to approximately half the control value. All lipid supplements resulted in high levels of
some trans-FA, mainly trans-11 C18:1 (vaccenic acid) but also trans-10 C18:1.This work was supported by the Spanish Ministry of Science and Innovation (MICINN;
AGL2008-04805). The authors from the Instituto de Ganadería de Montaña would like
to thank the Council of Castile and Leon for complementary financial support (GR158)
and the farm staff for their help in the field work. P.G. Toral gratefully acknowledges
receipt of a predoctoral grant from the CSIC (I3P Programme). The authors from the
Instituto del Frío (CSIC) wish to thank the Comunidad Autónoma de Madrid (S-
505/AGR-0153) and the Ministerio de Ciencia e Innovación (Consolider Ingenio 2010 Programme; FUN-C-FOOD CSD2007-063) for their financial support. They also wish
to thank M.V. Rodríguez-Pino for her technical assistance in the chromatographic
analysis.Peer reviewe