ABSTRACT
The objective of this study was to evaluate the effects of algae and cottonseed meal (CSM) supplementation on the fatty acid (FA) profile in the rumen fluid (RF) of steers fed a low-quality forage. Five Bos indicus crossbred steers, 187±7.5 kg liveweight (LW; mean±SD), were fed a low crude protein speargrass (Heteropogon contortus) hay as the basal diet alone or supplemented with either Spirulina platensis, Chlorella pyrenoidosa , Dunaliella salina , or CSM in Latin square design. The proportion of individual FA in the RF of steers varied in response to supplement, and these were most likely due to differences in the FA profile in supplements. Steers supplemented with Chlorella pyrenoidosa and CSM had a higher concentration of linoleic acid (C18:2n-6) in RF than unsupplemented steers or steers offered the other supplements, but there was no difference in the concentration in RF in steers supplemented with Chlorella pyrenoidosa and CSM. The concentration of linolenic acid (C18:3n-3) was higher in the RF of unsupplemented steers compared with supplemented steers. Steers receiving Chlorella pyrenoidosa supplementation showed an increase in total unsaturated FA in the RF compared with other supplemented and unsupplemented steers, which if transferred to meat, could have health related benefits to consumers. None of the supplements led to the formation of isomers known to inhibit fat synthesis.
Keywords:
biohydrogenation; conjugated linoleic acid; microalgae; tropical grass