Impact of dietary Chlorella vulgaris and carbohydrate-active enzymes incorporation on plasma metabolites and liver lipid composition of broilers

Abstract

Background Chlorella vulgaris has been proposed as a sustainable green feedstock in poultry nutrition due to its ease of cultivation, minimal environmental impact and balanced nutritional composition. However, the majority of studies documents the use of C. vulgaris as a dietary supplement in broilers instead of a feed ingredient. To the best of our knowledge, no report has shown the effect of a high-level incorporation (>2 % in the diet) of C. vulgaris on plasma metabolites and hepatic lipid composition of broilers. One hundred and twenty Ross 308 male birds were housed in 40 wired-floor cages and randomly distributed by the following experimental diets at 22 days of age (n = 10) during 15 days: (1) a corn-soybean meal based diet (control); (2) based diet with 10% of C. vulgaris; (3) diet 2 supplemented with 0.005% Rovabio® Excel AP; and (4) diet 2 supplemented with 0.01% of a pre-selected four-CAZyme mixture. Results The inclusion of C. vulgaris at 10% in the diet, regardless of the presence of exogenous CAZymes, changed plasma metabolites but did not compromise broilers growth. Plasma total lipids increased in broilers fed C. vulgaris combined with the two feed CAZymes (p < 0.001) compared with the control diet. Moreover, the supplementation with Rovabio® increased total cholesterol and LDL-cholesterol, while the addition of the four-CAZyme mixture increased triacylglycerols, VLDL-cholesterol and ALP activity. In opposition, HDL-cholesterol levels decreased in broilers fed microalga alone (p = 0.002). Regarding hepatic composition, the inclusion of C. vulgaris in broiler diets, individually or combined with exogenous CAZymes, had a minor effect on fatty acids but improved the n-6/n-3 ratio and total carotenoids. Conclusions In summary, the inclusion of a high level (10%) of C. vulgaris in broiler´s diet, regardless of the presence of exogenous CAZymes, improved hepatic antioxidant composition and did not impair broiler’s performance. In addition, the feed supplementation with CAZymes increased broilers lipemia. Therefore, dietary C. vulgaris at this incorporation level seems to be safe for animal health and do not compromise performance traits, with no need of CAZymes supplementation.

Combined effects of dietary Laminaria digitata with alginate lyase on plasma metabolites and hepatic lipid, pigment and mineral composition of broilers

“…The present study highlights cholesterol- and lipid-lowering properties of individual L. digitata , although the mechanism of this hypocholesterolaemic action is still unclear. As previously observed for some microalga species [ 29 ], this improved effect on lipemia upon supplementation with L. digitata can be attributed to a decrease in intestinal tract fat absorption [ 26 ]. Glucose was slightly increased in L. digitata fed broilers, independently of the addition of feed enzymes.…”

“…In addition, feeding brown macroalga Hizikia fusiformis by-products [ 24 ] and a purified polymannuronate from a brown alga mix [ 25 ] at 0.4 to 0.5% feed led to an increase of feed efficiency. It also should be underlined that the percentage of L. digitata incorporation in the diet and the duration of the experimental period impact broilers’ growth performance parameters [ 26 ]. In the present study, similarly to what was previously reported for polymannuronate polymer of alginate used as a feed supplement for broilers [ 25 ], the dietary supplementation with the in vitro selected alginate lyase [ 17 ] was expected to release bioactive polysaccharides from L. digitata cell wall, such as alginate, with prebiotic activity and, consequently, improve broiler performance.…”

“…Glucose was slightly increased in L. digitata fed broilers, independently of the addition of feed enzymes. Still concerning plasma reference values, the lowest level of urea was observed in L. digitata fed broilers suggesting unaffected renal function by the macroalga addition [ 26 , 29 ]. Regarding the hepatic markers, the variations observed for the enzymatic activities of ALP and GGT are still within the reference figures for birds [ 30 , 30 ] and therefore, are devoid of clinical physiological relevance.…”

“…Briefly, birds were raised under environmentally controlled conditions, with continuously monitored temperature and ventilation. Three birds were allocated per pen with 10 replicate pens per treatment, in order to reduce the number of animals used in the experiment (3R’s principle) and according to previous reports [ 26 , 46 ], and submitted to an adaptation period of 21 days, in which they were fed a corn and soybean meal-based diet, followed by an experimental period of 14 days until the standard slaughter age of 35 days (finishing period), in which they received one of the 4 experimental diets: 1) a corn-soybean meal based diet (Control); 2) the control diet with 15% of L. digitata powder (Algolesko; Plobannalec-Lesconil, Brittany, France) (LA); 3) the control diet with 15% of L. digitata powder and supplemented with 0.005% of a commercial CAZyme mixture, Rovabio® Excel AP (Adisseo; Antony, France) (LAR); and 4) the control diet with 15% of L. digitata powder and supplemented with 0.01% of a recombinant CAZyme (LAE). The Rovabio® Excel AP contained β-xylanase and β-glucanase, whereas the recombinant CAZyme was an alginate lyase belonging to PL7 family and described by Costa et al [ 17 ].…”

“…This mixture was homogenized for 1 min and centrifuged (at 3000 rpm for 5 min at 4 °C). The supernatant was separated and immediately analysed, following the same procedure described by Coelho et al [ 26 ]. The pigment contents were determined according to Hynstova et al [ 50 ].…”