Chemical-functional characterization of Ascophyllum nodosum and Phymatolithon calcareum and dietary supplementation in post-weaning pigs

Abstract

Introduction: As the livestock industry grapples with the need for sustainable land, maintaining production systems, and reducing antimicrobial resistance, the application of functional nutrition emerges as a potential solution.

Aim: In line with the One Health principles, this study aims to evaluate functional properties of Ascophyllum nodosum and Phymatolithon calcareum, and assess the effects of their dietary supplementation on piglets' health.

Materials and methods: A chemical-functional characterization was conducted before and after in vitro digestion. Total Polyphenols Content (TPC) and Total Flavonoid Content (TFC) were determined through colorimetric assays, while antioxidant activity was determined using ABTS assay, and the microdilution method was used to evaluate the antimicrobial capacity. For the in vivo trial twenty-four post-weaning pigs (28 ± 2 days, 6.89 ± 0.820 Kg) were enrolled in two homogeneous groups (n = 12/group): control group (CTRL) fed a commercial diet, and treated group (ALGAE) fed commercial diet with the addition of 1.5% of A. nodosum and 0.5% of P. calcareum for 27 days. Weekly, zootechnical performances were assessed monitoring the body weight and the individual feed intake. Fecal samples were collected to evaluate the abundance of total, lactic acid and coliform bacteria through plate counting. Serum were obtained at day 0 and day 27 to assess the antioxidant barrier.

Results and discussion: The chemical characterization discloses that the minerals' level remains below the maximum thresholds defined for their use in piglets nutrition. TPC was 330.42 ± 21.372 mg TAE/g of the sample and 11.45 ± 0.521 mg TAE/g of the sample for A. nodosum and P. calcareum, respectively, and a similar trend was found in the TFC evaluation (213.85 ± 20.557 and 2.71 ± 0.900 mg CE/g of sample, respectively). Our results also highlighted that polyphenols and flavonoid compounds persisted after in vitro digestion as well as the functional properties. The administration of algae in piglets diet, although it slightly affected feed efficiency in the first period of the trial, did not affect the animal growth in terms of weight and average daily gain. Microbiological analysis of feces showed similar values between the two experimental groups over 27 days. A significantly higher serum antioxidant barrier was registered in ALGAE compared to CTRL group at day 27 (363.26 ± 16.241 vs. 230.69 ± 32.078 HClO/mL, p < 0.05).

Conclusion: In conclusion, the supplementation with A. nodosum and P. calcareum could be considered a promising dietary strategy to enhance the oxidative barrier in weaned piglets.

Keywords: Ascophyllum nodosum; Lithothamnium calcareum; antimicrobial; antioxidant; bioactive compounds; functional ingredients; post-weaning pigs; seaweeds.

Figure 1

Experimental design from arrival date (28 days of animal age) to T4 (63 days of animal age) divided according to the diet administered.

Figure 2

Ascophyllum nodosum, Lithothamnium calcareum, and their combination extract growth inhibition capacity against F4⁺ E. coli. The data are shown as the means and standard errors. Asterisks (n = 3) with different superscripts indicate significantly different means; **p = 0.002, ***p < 0.001. Time: p < 0.001; Treatment: p < 0.001; Time x Treatment: p < 0.001.

Figure 3

Phenolic and flavonoid compounds in Ascophyllum nodosum, Lithothamnium calcareum and their combination after the in vitro digestion. (A) Total phenolic content (TPC) after in vitro digestion. Time: p < 0.001; Treatment: p < 0.001; Time x Treatment: p < 0.001; (B) Total flavonoid content (TFC) after in vitro digestion. Time: p < 0.001; Treatment: p < 0.001; Time x Treatment: p < 0.001. TAE, tannic acid equivalent; CE, catechin equivalent. The data are shown as the means ± standard deviations (SDs) (n = 3). Asterisks (n = 3) with different superscripts are significantly different; ***p < 0.001.

Figure 4

Percentage inhibition of radical scavenging activity (PI%) after in vitro digestion of Ascophyllum nodosum, Lithothamnium calcareum, and their combination. The data are shown as the means ± standard deviations (SDs) (n = 3). Asterisks (n = 3) with different superscripts are significantly different; ***p < 0.001; *p = 0.04. Time: p < 0.001; Treatment: p < 0.001; Time x Treatment: p = 0.001.

Figure 5

Growth inhibition of Ascophyllum nodosum, Lithothamnium calcareum and their combination against E. coli F4+ after the digestive process. The data are shown as the means ± standard deviations (SDs) (n = 3). Asterisks (n = 3) with different superscripts are significantly different; ***p < 0.001, **p < 0.004, *p = 0.02. Time: p < 0.001; Treatment: p < 0.001; Time x Treatment: p < 0.001; Subject: p = 0.007.

Figure 6

Zootechnical performance from T0 to T4. (A) Body weight at T0, T1, T2, T3, T4. Time: p = 0.0903; Treatment: p < 0.001; Time x Treatment: p = 0.5326; (B) Average Daily Gain (ADG) in the time interval T0 - T2 and T2 - T4. Time: p = 0.8631; Treatment: p < 0.001; Time x Treatment: p = 0.0426; Subject: p = 0.0914; (C) Average Daily Feed Intake (ADFI) in the time interval T0 - T2 and T2 - T4. Time: p = 0.2105; Treatment: p < 0.001; Time x Treatment: p < 0.002; Subject: p = 0.011; (D) Feed Conversion Rate (FCR) in the time interval T0 - T2 and T2 - T4. Time: p = 0.1860; Treatment: p < 0.001; Time x Treatment: p = 0.0152. The data are shown as the means ± standard error (SEM). Asterisks with different superscripts are significantly different; **p = 0.003, *p = 0.0166.

Figure 7

Microbiological analysis of feces. (A) Microbiological evaluation of total bacteria on PCA medium. Time: p = 0.9419; Treatment: p = 0.5631; Time x Treatment: p = 0.0697; (B) Microbiological evaluation of lactic acid bacteria on MRS medium. Time: p = 0.0838; Treatment: p = 0.8488; Time x Treatment: p = 0.8823; (C) Microbiological evaluation of coliform bacteria on VRBL medium. Time: p = 0.0432; Treatment: p = 0.0769; Time x Treatment: p = 0.5892. The data are shown as the means ± standard error (SEM).

Figure 8

Serum values of Oxy Adsorbent test measured at T0, T2, and T4 of trial in CTRL and ALGAE groups. The data are shown as the means ± standard error (SEM). Asterisks with different superscripts are significantly different; ****p < 0.0001, **p < 0.001. Time: p < 0.001; Treatment: p = 0.003; Time x Treatment: p < 0.001.