The aim of this study was to evaluate the effects of agro-industrial byproduct-based diets on the productive parameters, digestibility, insect composition, and gut microbiota of mealworm (Tenebrio molitor) larvae. Three formulations corresponding to three different levels of starch and protein were tested: one formulation based on bread remains and brewer’s yeast, representing a diet of high starch (61.1%) and low crude protein (18.5%) (HS-LP); and two formulations in which an additional four byproducts (courgette (Cucurbita pepo) remains, tigernut (Cyperus scelentus) pulp, brewer’s spent grains, and rice straw) were incorporated in different proportions, consistent with a diet of both moderate starch (29.8%) and crude protein (21.0%) (MS-MP); and another corresponding to a diet of low starch (20.0%) and high crude protein (26.3%) (LS-HP). A total of 1920 young larvae (average weight = 0.65 mg per larva) were used in this study. The larvae were randomly distributed into 16 replicates per treatment (boxes of 22.5 cm × 14.0 cm × 4.75 cm). Ten replicates for the growth performance–digestibility trial and six replicates for the complementary trial to determine uric acid levels in the frass were assigned per treatment. For growth performance, the diets were administered ad libitum during the experiment. The average number of days for the larvae to start pupating was lower in those reared on the HS-LP and LS-HP diets (88.90 and 91.00 days, respectively) than those on the MS-MP diet (120.09 days) (p < 0.001). The final individual weight was higher (p < 0.001) in larvae of the LS-HP group (168.69 mg) compared to those of the other groups (100.29 and 112.99 mg for HS-LP and MS-MP, respectively). However, the feed conversion ratio was better (p < 0.001) in the HS-LP group with the lowest value (1.39 g/g), with dry matter digestibility being the highest for the same diet (70.38%) (p < 0.001). Mealworms reared on LS-HP and MS-MP diets had a higher crude protein content than those reared on the HS-LP diet (p = 0.039). The most abundant phyla in the gut microbiota of larvae were Tenericutes, Proteobacteria, and Firmicutes, with their abundance depending on the rearing substrate. The representation of Tenericutes phylum was higher (p < 0.05) in the mealworms reared on MS-MP and HS-LP diets, whereas Proteobacteria and Cyanobacteria were higher in abundance (p < 0.001) in the insects reared on LS-HP. In conclusion, the larval growth, digestibility, insect composition, and gut microbiota of Tenebrio molitor were found to depend on the composition of the administered diet, and the results suggest great potential for the use of agro-industrial byproducts in their rearing and production.

The aim of the present study was to ascertain whether an Allium spp. extract rich in organosulfur compounds, such as propyl thiosulfonate (PTSO), added to the feed of growing-finishing pigs at 5 g/kg enhances growth performance or affects the fecal microbiome, the levels of short-chain fatty acids, or the antioxidant capacity of the animals. Fifty male growing pigs (large white) of 23.07 ± 2.87 kg average body weight were randomly allotted to two treatments in a 103-day trial. The trial was divided into two periods, an initial growing phase (56-days) and a finishing phase (47-days). Two dietary treatments for each phase (growing and finishing) were used: a control diet (CON) and an experimental diet consisting of the control diet to which 5 g/kg of Allium spp. extract was added to substitute sepiolite (GAR). Throughout the study, body weight, average daily gain (kg/day, ADG), feed intake (kg/day), and feed conversion ratio (kg/kg) were measured, while the backfat thickness and muscle depth were determined at the end of the study. Besides, feces samples were taken for bacterial counts by means of real-time PCR and short-chain fatty acid (SCFA) profile determination, and the antioxidant capacity was assessed in serum and saliva. In the animals receiving Allium spp. extract (5 g/kg) in the feed, ADG increased (p < 0.05) throughout the trial, Salmonella spp. and Clostridium spp. counts in feces had decreased (p < 0.05) when measured on day 56, and, by day 103, Salmonella spp., Clostridium spp., and Enterobacteriaceae counts had decreased (p < 0.05) and Lactobacillus spp. counts had increased (p < 0.01) in feces. Regarding the SCFA profile in feces and antioxidant capacity measured in serum and saliva, supplementation with Allium spp. extract significantly increased the levels of propionic, isobutyric, and isovaleric acids and the percentage of total branched fatty acids, while the c2/c3 and (c2 + c4)/c3 ratios were lower (p < 0.05) in feces; the Trolox equivalent antioxidant capacity and the cupric reducing antioxidant capacity levels in serum were significantly higher in the same pigs on day 103 than on day 0. Consequently, based on the current results, Allium spp. extract rich in organosulfur compounds, added to the diet at 5 g/kg, had a beneficial effect on the microbiota and would seem to be a possible alternative for increasing the growth performance of growing-finishing pigs. However, further studies on the effects of Allium spp. supplementation on carcass quality are necessary.

This work aimed to evaluate the effect of adding two different commercial antioxidants (AOX) products to pre-starter and starter diets using low vitamin E (Vit E as DL-α-tocopheryl acetate) levels on the growth performance and oxidative stress of piglets for the first six weeks post-weaning (PW). They were sorted by initial body weight (BW: 6.175 ± 0.931 kg) and randomly allotted to four dietary treatments (with six replicates per treatment): a positive control (PC) and a negative control (NC) diet, with normal and low dose of vitamin E (80 and 15 mg kg⁻¹, respectively), both without AOX; the other two experimental diets with a low dose of vitamin E (LVE) plus LOXIDAN VD100 (LVE + AOX1) or LOXIDAN E Ros (LVE + AOX2). Growth data were recorded, and blood samples were taken, at the beginning (day 0) and at the end of each feeding period: pre-starter and starter (at days 14 and 42, respectively). No differences among dietary treatments were found with respect to growth performance in the pre-starter period (p ≥ 0.05). However, at the end of the starter period, a lower BW was found in piglets fed the NC diet compared to the other dietary treatments. Differences in daily gain and feed conversion ratio were also found either for the starter period or when the whole period was considered (p < 0.05), whereby piglets fed PC or LVE diets supplemented with AOX showed better growth performance compared to piglets fed the NC diet. Regarding Vit E (α-tocopherol) serum levels, there were no differences among treatments at day 0; but the serum values of this vitamin decreased in LVE diets at 14 and 42 days, but not in the PC. On day 42, the highest levels of α-tocopherol in liver were also found in piglets fed PC (p < 0.05). Nevertheless, in general, from a metabolic point of view and after checking the serum biochemical profile of piglets, there were no differences in other oxidative stress markers (p ≥ 0.05). The results showed that the AOX products used were able to compensate for the lower Vit E supply with respect to growth performance in the starter phase. The use of AOXs or usual levels of Vit E in feed constitutes a key factor in achieving optimal growth performance of piglets in the PW period.

Olive pulp (Olea europaea) inclusion in the diet of Iberian sows (Sus scrofa) is interesting due to fiber and bioactive compounds content and because both productions are located in the same area. The aim of this trial was to study the effect of olive pulp inclusion at 100 g/kg in Iberian sow’s diet on performance, immunoglobulin and serum parameters, antioxidant status, and fecal microbiota. Forty multiparous Iberian sows (body weight (BW) = 149.6 ± 20.2 kg) were assigned either a control diet (CON) or an experimental diet (PUL) with olive pulp at 100 g/kg. The BW and backfat thickness in sows were measured at post-insemination days 42 and 107, and litter performance was measured on the farrowing day. Blood and fecal samples were collected at gestation day 107. In piglets, blood was sampled when they were 10 days old for immunoglobulin analysis. Albumin, total protein, triglyceride, creatinine, urea, glucose, and Trolox equivalent antioxidant capacity in serum were higher (p < 0.05) in PUL sows than in CON sows. The Enterobacteriaceae, Bifidobacterium spp., and Lactobacillus spp. fecal counts were increased (p < 0.05) with olive pulp supplementation compared with the CON sow group. Olive pulp added to gestating Iberian sow’s diet at 100 g/kg has beneficial effects on the fecal microbiota and antioxidant status, without penalizing other gestation parameters.

Given the significant environmental consequences of current poultry feed practices and the heavy dependence of the European Union on imported soybeans, studying alternatives is crucial. This study evaluated the potential benefits of using locally sourced alternative plant-based ingredients and whole dry black soldier fly larvae in the diet of laying hens. The experiment involved 120 Isazul hens at 23 weeks old, which were divided into three groups with five replicates each (eight hens per replicate): a control diet (CON) based on soybean meal and cereals, an alternative diet (ALT) replacing the soybean meal with locally sourced plant-based resources (peas, distillers’ dried grains with solubles, and sunflower meal), and the ALT diet supplemented with 5% whole dry black soldier fly larvae (ALT+DBSFL). Over 15 weeks, the hens were fed ad libitum, and the production performance, egg quality, and plasma biochemical parameters were assessed across three experimental sub-periods. The results showed no significant differences in body weight, feed intake, egg production, egg weight, egg mass, or feed conversion ratio across the diets (p > 0.05). The egg quality remained consistent across all the groups; however, the hens fed the ALT+DBSFL diet exhibited higher Haugh units in the first experimental sub-period (p < 0.05) and lower plasma cholesterol and triglycerides at 32 weeks of age (p < 0.05). The findings of this study indicate that incorporating these alternative ingredients and whole DBSFL into layers’ diets does not compromise production performance, egg quality, or biochemical parameters related to health status, supporting their potential as sustainable feed alternatives.

This work studied the effects of the inclusion of Clostridium butyricum on feed, alone or with carob meal or citrus pulp, on the digestive and metabolic status of weaned piglets. A total of 30 male piglets (weaned at 21 days) is used. There are five dietary treatments: negative without ZnO at high doses (C−), a positive control supplemented with ZnO at 2500 ppm of Zn (C+), supplemented with Clostridium butyricum as a probiotic (PRO), and supplemented with probiotic and 5% carob meal (PROC) or 5% citrus pulp (PROP). During the experiment (27 days), the piglets were periodically weighed and sampled for a serum biochemical, fecal microbiological, intestine histological, and digestive status analysis. The body weight, apparent ileal digestibility of dry matter (DM), and fecal microbiology were not affected by the treatments (p ≥ 0.05). However, the apparent fecal digestibility of DM was lower for the C− treatment than for C+ (p < 0.05), and the total concentration of volatile fatty acids (VFAs) in feces with C+ was lower than that for the PROC treatment (p < 0.05). The treatments with the probiotic had a higher molar proportion of butyric acid in feces than C+, and it was found that C− reached an intermediate value (p < 0.01). No general effects of diet were found on the histological measures performed on the jejunum and ileum, and in the serum biochemical analysis (p ≥ 0.05), only the concentration of interleukin-8 was lower for the PROC treatment compared to the C−, C+, and PRO treatments (p < 0.05). In conclusion, the intestinal wellness of piglets could be improved with the supplementation of Clostridium butyricum by increasing butyric acid, and this effect was not altered with the inclusion of carob meal or citrus pulp. More studies under commercial conditions are needed, as the effects might be different in more challenging environmental circumstances.