Association between dietary components and muscle fatty acid deposition
in longissimus dorsi: Results from a metabarcoding diet analysis of
grazing Tan sheep
Abstract
Understanding the natural diets of grazing herbivores can help fulfill
their nutritional requirements and develop management strategies.
Emerging metabarcoding techniques can provide more accurate estimates
for dietary composition of grazing animals. Thirty-nine Tan sheep with
weights of 25.10 ± 1.88 kg were randomized into three groups: the
grazing group, the time-limited grazing group, and the stall-fed group.
Effects of grazing on meat fatty acid composition in lambs were compared
to concentrate-based systems. Simultaneously, we investigated sheep
diets using DNA metabarcoding of feces to assess the prevalence of
medicinal herbage plants consumed by grazing sheep. Metabarcoding data
determined that Lespedeza sp., Artemisia sp., Chenopodium sp.,
Corispermus sp., and Phellodendron amurense were predominant with
different proportions (P < 0.05). Our results demonstrated
that grazing systems could transform the muscle fatty acid composition
and promote n-3 PUFAs, including C18:3n3 (ALA), C20:5n3 (EPA), and
C22:6n3 (DHA) deposition. To establish the association of PUFAs with the
herbage taxa, we conducted multivariate and correlation analyses. Some
highlighted herbage species (e.g., Bassia scoparia, Euphorbia humifusa,
and Arnebia euchroma) were significantly correlated with omega-3 PUFAs.
The dominant group Lespedeza sp. showed a positive correlation with
C18:2n6. Overall, these results demonstrated the utility of
metabarcoding diet analysis and how diversification in dietary
composition was associated with muscle fatty acid deposition. This
research examined the correlation between herbage taxa and omega-3 fatty
acids, and the results provide an initial view of the effects of herbage
on PUFAs of lambs. The study provides experimental evidence for future
feeding research.