Fatty acid composition, including c

Fatty acid composition, including conjugated linoleic acid, of intramuscular fat
from steers offered grazed grass, grass silage, or concentrate-based diets

ABSTRACT: The effects of grazed grass, grass silage,
or concentrates on fatty acid composition and conjugated
linoleic acid (cis-9,trans-11-18:2; CLA) concentrations
of i.m. fat of steers fed to achieve similar carcass
growth rates were investigated. Fifty steers were divided
into 10 blocks based on body weight and assigned
at random from within blocks to one of five dietary
treatments. The experimental rations offered daily for
85 d preceding slaughter were 1) grass silage for ad
libitum intake plus 4 kg of concentrate, 2) 8 kg of concentrate
plus 1 kg of hay, 3) 6 kg of grazed grass DM
plus 5 kg of concentrate, 4) 12 kg of grazed grass DM plus 2.5 kg concentrate, or 5) 22 kg of grazed grass
DM. The concentration of polyunsaturated fatty acids
(PUFA) in i.m. fat was higher (P < .05) for steers offered
ration 5 than for those given any other ration. Decreasing
the proportion of concentrate in the diet, which
effectively increased grass intake, caused a linear decrease
in the concentration of i.m. saturated fatty acids
(SFA) (P < .01) and in the n-6:n-3 PUFA ratio (P < .001)
and a linear increase in the PUFA:SFA ratio (P < .01)
and the conjugated linoleic acid concentration (P <
.001). The data indicate that i.m. fatty acid composition
of beef can be improved from a human health perspective
by inclusion of grass in the diet.