Abstract :
Inclusion of oil palm fronds (OPF) in ruminant diets was previously reported to increase
the tissue content of unsaturated fatty acids (UFAs) and reduce rumen biohydrogenation,
which was in contrast with our former in vitro study. Thus, a small scale in vivo study was
performed to assess the effects of different inclusion levels of OPF on UFA content of intramuscular
fat (longissimus dorsi, biceps femoris) and adipose tissues (subcutaneous, perirenal).
Sixteen lambs were divided into 4 treatment groups, with dietary inclusion levels of OPF
of 0, 100, 200 and 300 g/kg DM, respectively. Further, the diet contained a commercial
sheep/goat pellet. Diets were supplemented with soybean oil (40 g/kg DM), which was
equally mixed with the whole ration. Hence, the diet particularly supplied linoleic acid (LA;
563–569 g/kg total fatty acid (FA) intake). Due to selective refusal of the OPF, actual proportion
of OPF in the ingested feed was lower compared with the offered diet, i.e. 44, 137
and 170 g/kg DM. The total fat intake also differed among the treatments due to differences
in feed intake. After 12 weeks on the experimental diets, the lambs were slaughtered and
both intramuscular fat and adipose tissues were collected for FA analysis. No differences
were observed in total FA content, proportion of C18:2 n-6 and UFA/SFA ratio in OPF inclusion
groups for both intramuscular fat and adipose tissues. Hence, OPF does not seem to
relatively modify UFA content of adipose or intramuscular fat.
