Astaxanthin combined with larvae meal as a feed additive positively impacts health index and growth performance in weaned pigs.
Weaning is a stressful period that reduces digestive capacity and increases oxidative stress and disease susceptibility in piglets. Feed additives can naturally protect the health condition of piglets. This study aimed to evaluate the effects of supplementation with full-fat H. illucens (HI) larval meal and astaxanthin (AST) on growth performance and health status of weaned pigs. HI contains biologically active substances (chitin, antibacterial peptides, lauric acid) with immunostimulating, antibacterial and anti-inflammatory properties. Astaxanthin is a carotenoid pigment with powerful antioxidant and anti-inflammatory properties. The results showed that astaxanthin supports the inhibition of oxidative stress. In the experiment lasting from 35 to 70 days of age, 48 weaned pigs (body weight about 8.7 kg) participated. Both supplements were tested separately or combined in feed mixtures. The addition of 2.5% HI and AST can reduce the susceptibility of lard to oxidation. However, higher concentrations of HI (5%) are not beneficial due to adverse changes in some red blood cell indices and therefore need to be combined with the antioxidant AST to improve these indices. Neither supplement had a negative effect on piglet performance.
Abstract
Weaning is an important stage in livestock production and therefore the search for health-promoting feed additives of natural origin is necessary. This study aimed to evaluate the effects of supplementation with full-fat H. illucens (HI) larval meal and astaxanthin (AST) on growth performance and health status of weaned pigs. The experiment was performed on 48 pigs (8.7 kg) divided into 6 groups: I—control; II—HI 2.5%; III—HI 5%; IV—2.5% HI and AST; V—5% HI and AST; VI—AST. The experiment lasted from day 35 to day 70 and animals were fed ad libitum. The results obtained indicated that meal HI and astaxanthin did not affect food intake and utilization, weight gain or organ weight. In addition, blood indicators are still within the norm. It appears that astaxanthin supports the inhibition of oxidative stress, which becomes apparent in the case of certain red blood cell parameters. The addition of 2.5% HI and AST may reduce the susceptibility of lard to oxidation (lower adipose tissue TBARS). However, 5% HI in feed is not beneficial due to adverse changes in some red blood cell indices and needs to be combined with the antioxidant AST to improve these indices.
One of the major problems causing economic losses in pig farming is the weaning period of piglets [ 1 ]. There is a very stressful period in the animal’s life, involving separation from the sow, environmental and nutritional changes that increase exposure to pathogens and food antigens [ 2 ], as well as a new team hierarchy. Weaning of sows disrupts the intestinal integrity of piglets, reduces the digestive capacity of the digestive system, and increases intestinal oxidative stress and disease susceptibility in piglets [ 3 ]. One of the main factors influencing piglet health is the diet, and an important component of the diet is easily digestible protein with a favorable amino acid composition. Currently, the main protein sources for monogastric animals are post-harvest feeds and oil cakes (e.g. soybeans, rapeseeds), legume seeds, proteins of animal origin or algal biomass [ 4 , 5 , 6 ]. Rapid population growth and the growing demand for meat and products of animal origin have increased the need for quantities of protein-rich foods. Finding new protein sources has become necessary because of the scarcity of plant-based food protein sources due to unfavorable climate change and aversion to genetically modified foods, so finding new protein sources has become necessary. setting [ 6 ].
Attention has begun to turn to insect powders, which may provide additional sources of nutritional ingredients [ 7 , 8 , 9 ]. Improved protein products obtained from various insect species have begun to be used as salmon feed [ 10 , 11 ] as well as livestock feed [ 12 ]. As a result, interest in black soldier fly ( Hermetia illucens ) larvae (HI) as a sustainable source of protein for livestock has increased significantly. The advantage in insect production is that they can be grown at high densities and have high biological conversion rates [ 9 ]. Organic biomass, by-products or food waste can be used for production, contributing to more efficient management of organic and inorganic nutrient sources, especially the recycling of nitrogen and phosphorus [ 8 , 13 ]. There are currently two types of H. illucens larvae meal in animal feed: defatted and full-fat, where the main difference is the fat and saturated fatty acid content [ 6 ]; in the present experiment, a full-fat meal from H. illucens larvae was used. The crude protein content of the HI full-fat meal was 426 g/kg, the crude fat content was 264 g/kg, the crude fiber content was 91 g/kg and the ash content was 85 g/kg. Noteworthy is the amino acid composition in black soldier fly larvae powder. The most abundant essential amino acids are leucine (26.2 g/kg), lysine (21.6 g/kg) and phenylalanine + tyrosine (36.2 g/kg). Promising in terms of improving the health status of animals is the presence in insects of bioactive substances such as chitin, antibacterial peptides and specific fatty acids (especially lauric acid) that have stimulant properties. immunostimulant, antibacterial and anti-inflammatory [14, 15]. These bioactive compounds appear to be useful feed additives to support the growth and health of piglets by stimulating their immune response, which is important when carrying out animal husbandry. Intensive farming and limited treatment, especially with antibiotics.
The piglet’s body develops rapidly, associated with a rapid metabolism. This and weaning stress influence the production of significant amounts of free radicals [ 16 ]. Reactive oxygen species from the mitochondrial electron transport chain or excessive NAD(P)H stimulation causing oxidative stress may be important mediators of damage to cellular structures, including lipids. and membranes, proteins, and DNA [ 17 ]. Therefore, supplementing the diet with antioxidants appears to be beneficial, possibly helping to counteract the negative effects of oxidative stress [ 18 ]. As an antioxidant in the present experiment, astaxanthin was used, which is one of the carotenoid pigments with strong antioxidant, anti-inflammatory and anti-cancer properties [ 19 ]. The antioxidant properties of astaxanthin are 14 times greater than vitamin E, 54 times greater than β-carotene, and 65 times greater than vitamin C [ 20 ]. Additionally, astaxanthin is thought to protect against apoptosis by regulating mitochondrial proteins [ 21 ]. A study by Macedo et al. (2010) [ 22 ] found that astaxanthin, by reducing the levels of inflammatory cytokines in lipopolysaccharide-stimulated neutrophils, improved neutrophil phagocytosis and their bactericidal ability , while also reducing the amount of hydrogen peroxide and superoxide anion they produce.
Given the above, this experiment aimed to study the effects of Hermetia illucens larvae powder and astaxanthin as feed additives, with the potential to improve the health status and production indicators of weaned pigs. Blood health indicators (biochemical and hematological), growth performance and meat quality characteristics were estimated.
2. MATERIAL AND METHOD
2.1. Ethics approval
All procedures in this study involving the use of live animals were in agreement with the First Local Ethical Committee on Experiments with Animals in Cracow, Poland (Resolution No. 420/2020, July 22, 2020). During the experiment, the health status of post-weaned pigs was regularly monitored by veterinarians.
2.2. Animals and experimental setup
The experiment was conducted on 48 35-day-old weaned pigs weighing about 8.7 kg (±0.2 kg). The strollers belong to the Polish Landrace (PL) breed. Pigs were divided into six groups, each group had 8 animals: group I—control, group II—supplemented with 2.5% Hermetia illucens larvae powder (HI), group III—supplemented with 5% H. illucens larvae powder , group IV—supplemented 2.5% H. illucens larvae powder and astaxanthin, group V—supplemented 5% H. illucens larvae powder and astaxanthin, group VI—supplemented astaxanthin. Hermetia illucens larvae powder is a full-fat product obtained from commercial sources (HiProMine SA, Robakowo, Poland). Astaxanthin is derived from Haematoccus pluvialis (Podkowa AD 1905 sp. z oo, Lublin, Poland) and is added at an amount of 0.025 g per 1 kg (25 mg per kg) of the feed mixture. All piglets were fed an iso-protein and iso-energy diet, meeting the requirements of Polish pig farming standards [ 23 ]. The ingredient composition and nutritional value of the diets are shown in Table 1. Basic chemical analyzes of feed mixture samples were performed according to standard methods [ 24 ].
Abbreviations: HI—Hermetia illucens larvae powder ; AST—astaxanthin. I, II, III, IV, V, VI—number of groups: group I—control, group II—supplemented with 2.5% of Hermetia illucens (HI) larvae powder, group III—supplemented with 5% of H larvae powder . illucens , group IV—supplemented 2.5% H. illucens larvae powder and astaxanthin, group V—supplemented 5% H. illucens larvae powder and astaxanthin, group VI—supplemented astaxanthin. * Content in 1 kg premix: vit A—2,400,000 IU; vit D3—400,000 IU; vitamin E—8000 IU; vitamin B1—400 mg; vitamin B12—6000 µg; vitamin B2—1000 mg; vitamin B5—3000 mg; vitamin B6—600 mg; vitamin K—400 mg; biotin—30,000 µg; niacin—5008.3 mg; folic acid—100 mg; pantothenic acid—2760 mg; choline—24,193.548 mg; betaine—12,000 mg; Cu—20,000 mg; Fe—20,000 mg; I—200 mg; Mn—8000 mg; Se—60 mg; Zn—24,000 mg; Ca—267,979 g; Cl—6,268 g; K—0.066 g; Mg—30 g; Na—0.037 g; S—22.245 g. ** Exchange energy was calculated using the Hoffmann and Schiemann equation (1980) [ 25 ].
The experimental fattening lasted 35 days. Pigs were kept in separate pens and were fed and watered freely. Animals were weighed separately on the first and last days of the experiment. Daily feed intake and feed conversion as well as animal weight gain were calculated. At the end of the experiment, all pigs were slaughtered. The animals were killed according to approved standard methods by simple anesthesia using a specialized penetrating device Blitz (Germany), together with specialized 9 × 17 mm cartridges for pig slaughter. Blood was collected in tubes for biochemical and hematological analysis. Portions of intestine, kidney, stomach, liver, and spleen were collected for weighing. Samples of muscle ( longissimus m. ) and adipose tissue (back fat) were also taken from the area between the last thoracic vertebra and the first lumbar vertebra. The dissected intestinal sections (duodenum, jejunum, ileum, cecum, and colon) were washed, weighed, and measured. The pH of the stomach, duodenum, jejunum, ileum, colon, and cecum was measured using an HI 99163 pH meter (Hanna Instruments Inc., Woonsocke, RI, USA), with automatic temperature compensation from −5 to 105 °C and equipped with a pH/T° FC 232 combination electrode.
2.3. Blood analysis
2.3.1. Hematological parameters
Full blood samples were analyzed using a Vet Mythic 18 automated hematology analyzer (Orphée C2 Diagnostics, France). Parameters evaluated were total white blood cell (WBC), lymphocyte (LYM), monocyte (MON), granulocyte (GRA) count, red blood cell count (RBC), hemoglobin content factor (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean hemoglobin (MCH), red blood cell distribution width (RDWC), platelet count (PLT) and mean corpuscular volume their average (MVP), platelet size heterogeneity index (PDW) and platelet size (PCT).
2.3.2. Biochemical parameters
Blood samples for determination of biochemical parameters were collected in vitro and centrifuged (3500 × g , 15 min, 4 °C) to obtain serum samples. Biochemical indices were colorimetrically measured using Cormay test kits (Lublin, Poland) and a BS-180 biochemical automatic analyzer (Shenzhen Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China). National). The following parameters were determined: total cholesterol (CHOL), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triacylglycerides (TG), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), glucose (GLU), albumin (ALB), creatinine (CREA), urea (UREA), total protein (TP), calcium (Ca), phosphate (P), magnesium (Mg ), iron (Fe).
2.4. Collect and analyze meat and back fat samples
Meat ( longissimus m .) and adipose tissue (back fat) samples were taken from the area between the last thoracic vertebra and the first lumbar vertebra. Basic chemical analyzes (dry matter, crude protein, crude fat, and crude ash) of the meat samples were performed according to standard methods [ 24 ]. Thiobarbituric acid reactive substances (TBARS) were analyzed in meat and backfat samples after 3 months of storage at –20°C, using a modified method described by Pikul et al. (1989) [ 26 ]. Briefly, 10 g of shredded sample was homogenized with 50 mL of 4% perchloric acid with butylated hydroxytoluene. After filtration, 5 mL of the filtrate was mixed with 5 mL of 2-thiobarbituric acid (0.02 M). This solution was heated in a test tube for 1 hour, in a boiling water bath, then cooled under running water for 10 minutes. Measurements were performed at 532 nm based on a standard curve containing blank sample.
2.5. Statistical analysis
Data were analyzed by 2-way ANOVA using Statistica ® ver. 13.3 software package (StatSoft Inc., Tulsa, OK, USA) [ 27 ]. This model includes two main factors: (1) The proportion of Hermetia illucens larvae meal (2.5% vs. 5.0%) and (2) the presence of astaxanthin in the feed mixture and the interaction of them. Each individual piglet served as the experimental unit (n = 8, per group). Before data analysis, the normality of the data was tested using the Shapiro–Wilk test and histograms were evaluated. The Duncan test was used to compare differences between means when the difference was found to be significant ( p < 0.05).
3. RESULTS
3.1. Growth performance
All animals were healthy during the experiment and showed no signs of illness. Weight gain index, feed conversion ratio, average daily gain, feed intake and parameters collected during the dissection process are shown in Tables 2 and 3. There are no significant differences. statistical significance between groups.
I, II, III, IV, V, VI—number of groups; Hermetia illucens share 0% (groups I and VI), Hermetia illucens share 2.5% (group II and group IV), Hermetia illucens share 5% (group III and group V) and astaxanthin supplement (group IV, V and VI), no astaxanthin added (groups I, II and III).
I, II, III, IV, V, VI—number of groups; Hermetia illucens share 0% (groups I and VI), Hermetia illucens share 2.5% (group II and group IV), Hermetia illucens share 5% (group III and group V) and astaxanthin supplement (group IV, V and VI), no astaxanthin added (groups I, II and III).
3.2. Blood index
The effects of insect powder from Hermetia illucens larvae used at different doses and astaxanthin on blood biochemical indices, as well as the interaction between these factors, are shown in Table 4. Lipid composition was not affected by the HI meal, except for HDL (p = 0.03) and LDH (p <0.01) content, and was not affected by dietary astaxanthin supplementation. Analyzing liver/pancreas, kidney, and bone characteristics, several different effects of experimental nutritional factors were observed. The HI meal reduced GLU content ( p < 0.05) when supplemented at 5% in the feed, while astaxanthin supplementation increased GLU and ALP content. However, in the case of ALP as well as ALB content, the interaction was statistically significant: these parameters were higher when astaxanthin was added to the feed mixture along with the HI meal. Feed supplementation with 2.5% HI meal increased the level of p ( p < 0.01) and decreased CREA level ( p = 0.02) in piglet blood, while supplementation with 5% HI meal decreased Ca levels ( p < 0.01). Blood Mg levels are not affected by supplementing HI meals with food. Astaxanthin increased CREA, Ca and Mg levels ( p < 0.01). An interaction ( p < 0.01) between both nutritional factors was observed in blood TP levels, which were lowest in piglets receiving a feed mixture containing HI powder without astaxanthin.
I, II, III, IV, V, VI—number of groups; Hermetia illucens share 0% (groups I and VI), Hermetia illucens share 2.5% (group II and group IV), Hermetia illucens share 5% (group III and group V) and astaxanthin supplement (group IV, V and VI), no astaxanthin added (groups I, II and III). a,b,c,d —values within a row with different superscripts are significantly different at the p 0.05 level. Abbreviations: CHOL—total cholesterol, HDL—high-density lipoprotein, LDL—low-density lipoprotein, TG—triacylglycerides, LDH—lactate dehydrogenase, ALT—alanine aminotransferase, AST—aspartate aminotransferase, ALP—alkaline phosphatase, GLU— glucose, ALB—albumin, CREA—creatinine, UREA—urea, TP—total protein, Ca—calcium, P—phosphate, Mg—magnesium.
The results of hematological analysis of piglet blood are shown in Table 5. Astaxanthin supplementation did not affect white blood cell counts, while the 5% HI meal increased LYM counts ( p = 0.04). Significant interactions indicated that MON and GRA were only affected when both dietary factors were used together, and the highest amounts of MON and GRA were observed in piglets fed a mixture containing 5 meals % HI plus AST ( p = 0.01 and 0.02, respectively) . Both HI and AST meals affected red blood cell parameters (p < 0.05), but the interaction was significant only for HCT and MCV. The lowest values of these parameters were read in groups fed 5% HI meal supplement ( p < 0.01; p = 0.02). Analyzing the main factors, the significant increase in RDWC level after AST and 5% HI supplementation was remarkable ( p < 0.01). RBC count increased after AST supplementation (p <0.01) but was not affected by the HI meal in the diet. Fe levels were lower in the blood of piglets fed with HI powder ( p = 0.01) but were approximately 30% higher after astaxanthin supplementation ( p < 0.01). HGB levels decreased after supplementation with the AST meal ( p <0.01) and the 5% HI meal ( p =0.02). Both AST and HI 5% meals reduced MCH (p < 0.01). In the case of platelet parameters, the only effect was observed in PDW when using a 2.5% HI meal in the feed mixture, which significantly reduced this value ( p < 0.01 ).
I, II, III, IV, V, VI—number of groups; Hermetia illucens share 0% (groups I and VI), Hermetia illucens share 2.5% (group II and group IV), Hermetia illucens share 5% (group III and group V) and astaxanthin supplement (group IV, V and VI), no astaxanthin added (groups I, II and III). a,b,c,d —values within a row with different superscripts are significantly different at the p 0.05 level. Abbreviations: WBC—white blood cells; LYM—lymphocyte; MON—monocyte; GRA—granulocytosis; RBC—red blood cells; HGB—hemoglobin; Fe—iron; HCT—red blood cells; RDWC—red blood cell distribution width; MCV—mean corpuscular volume; MCH—mean hemoglobin; PLT—platelets; PDW—platelet distribution width; PCT—platelet; MPV—mean platelet volume.
3.3. Analyze meat and back fat
The effects of astaxanthin and H. illucens larvae powder on the basic chemical analysis of meat are shown in Table 6. The highest meat dry matter was determined in piglets fed 2.5% HI powder or 2.5% HI powder combined with AST (interaction p = 0.02). The lowest ash percentage in meat (on dry matter basis) was determined in the group treated with 2.5% HI powder ( p < 0.01) and in the group not treated with AST ( p = 0.03). The protein and fat content of meat (on a dry matter basis) was not affected by the HI meal nor by the addition of AST in the feed.
I, II, III, IV, V, VI—number of groups; Hermetia illucens share 0% (groups I and VI), Hermetia illucens share 2.5% (group II and group IV), Hermetia illucens share 5% (group III and group V) and astaxanthin supplement (group IV, V and VI), no astaxanthin added (groups I, II and III). a,b,c —values within a row with different superscripts are significantly different at the p 0.05 level.
Results of measuring the oxidative stability of meat and adipose tissue in pigs fed with a mixture of Hermetia illucens or astaxanthin powder are presented inTable 6. Both HI and AST meals significantly reduced TBARS in adipose tissue (back fat) after 3 months of frozen storage (p < 0.01) and the interaction between these factors resulted in p < 0.01. Compared to the control group, the 2.5% HI concentration was more effective than the 5% HI concentration (TBARS reduction 80% vs 69%) and AST was more effective when used alone or with 2.5% HI added to food. mixed (TBARS reduced by about 77%). However, in the case of meat, HI meal supplementation did not affect TBARS values, while AST supplementation increased this parameter ( p < 0.05).
4. DISCUSS
4.1. Growth performance
Inclusion of H. illucens larvae powder in the diet did not adversely affect the growth performance of piglets participating in this study and no effect of the HI meal on the weight of organs and gastrointestinal tract was observed. of piglets (calculated as % of body weight). In contrast, in the experiment by Yu et al. (2020) [28], piglets fed mixtures containing 0%, 1%, 2% or 4% HI meal showed linear increases in pancreas and small intestine in response to dietary supplementation. this diet. No negative effects on feed intake, feed conversion ratio or average daily gain were observed. The fact that the presence of HI powder in the feed did not reduce the feed intake of piglets is a favorable result and confirms that insect-based feed is highly palatable to these animals. . The interest of piglets and their willingness to eat black fly larvae has also been observed by other authors [ 29 ]. Conclusions similar to ours were reached by Biasato et al. (2019) [ 30 ], who performed an experiment on weaned piglets fed defatted H. illucens larvae powder . HI larval meals were included in increasing amounts (0%, 5% or 10%) in diets formulated for two feeding periods: I (from days 1 to 23) and II (from days 24 to 61). No significant differences in growth performance were observed, except for mean daily feed intake during phase II, which showed a linear response to increasing HI meal levels. Additionally, no effects were observed on growth performance of weaned piglets fed diets containing up to 8% full-fat HI meals for 15 days [ 31 ]. Driemeyer (2016) [ 32 ] also found no difference in piglet performance when fish meal was partially replaced with HI meal. The researcher fed piglets (10 to 28 days old) on a 4-week phased feeding schedule with a diet containing 3.5% HI meal. There were no significant differences in animal feed intake and average daily growth. In contrast, in the study by Chia et al. (2021) [ 33 ], the effect of H. illucens meals on daily weight gain was observed. Carcass weight of pigs fed diets containing HI meal replacing fishmeal at 50%, 75% or 100% ( w / w ) was higher than that of pigs fed control diets. In groups receiving 50% and 100% insect meal in place of fish meal, final body weight was significantly higher than in the control group and the group treated with 25% insect meal. In our trial, no significant differences in final body weight were observed between groups and no significant differences in feed conversion ratio (FCR). In contrast, in experiments with 50%, 75% or 100% insect powder, the FCR was significantly lower than the control group and 25% insect powder [ 33]. In another study [ 28 ], crossbred pigs weighing approximately 76.0 kg were divided into three groups in which they received increasing amounts of H. illucens food (0%, 4%, or 8%). The results showed that the 4% HI diet significantly increased the final body weight and average daily gain of pigs and reduced the feed-to-gain ratio compared to the 0% and 8% HI diets. There was no difference in mean daily intake between all three groups. A study [ 34 ] was conducted over 40 days to investigate the effect of increasing levels of HI larval oil supplementation on the growth performance of newly weaned pigs (at 21 days of age) housed in a feeding program three stages. It was found that supplementation with 0%, 2%, 4% or 6% insect oil linearly increased (p < 0.05) body weight on days 14, 21, 25, 33 and 40, but does not affect food intake. throughout the entire experiment. However, daily weight gain and feed conversion ratio only improved linearly during the first culture period from 0 to 14 days of the experiment. When weaned piglets received feed mixtures containing 5%, 10% or 20% HI meal [ 35 ], no significant linear effects on weight gain and feed efficiency were observed. Looking at the nutritional factor, which is an insect product from Hermetia illucens , it is conceivable that the diversity of results observed in the studies cited above could be due to both the type of product (powder, oil) and the time that the pigs eat. included in the experiment. This statement is consistent with the observation of a linear improvement in both ADG and FCR when HI meal supplementation in the feed increased from 0%, 1%, 2%, to 4% during the first two weeks post-weaning. , while there is no difference. found during a four-week feeding period [ 36 ].
A significant effect of astaxanthin supplementation at an amount of 25 mg per kg of feed on growth performance of weaned piglets was not observed in this experiment. Similarly [ 37 ], supplementing pig diets with astaxanthin (1.5 or 3 mg per kg of feed) did not affect average daily gain, average daily feed intake, or conversion rate. change food. When analyzing the nutritional factor astaxanthin, it is important to note the small number of articles describing the effects of AST supplementation on production performance in pigs. Therefore, the discussion must be expanded to include other monogastric species. Ao and Kim (2019) [ 38 ] tested Pekin ducks fed astaxanthin derived from Phaffia rhodozyma . A total of 1440 1-day-old female Pekin ducks (about 52 g) were divided into three groups: control group—0 mg AST/kg diet, group I—3458 mg AST/kg diet, and group II —6915 mg AST/kg diet. It was found that on days 22 to 42, AST supplementation increased weight gain and reduced feed-to-gain ratio. Throughout the trial, weight gain and final body weight were higher in the AST treatment group than in the control group. AST supplementation at an amount of 25 mg per kg of feed, as in the present experiment, did not affect organ weights. In an experiment by Jeong and Kim (2014) [ 39 ], 1-day-old male chickens were used to test the effect of AST derived from P. rhodozyma on breeding rate. Chickens were supplemented with 0, 2.3 or 4.6 mg AST/kg of feed. AST supplementation improved weight gain at finishing and throughout the trial and reduced feed conversion ratio at finishing. Therefore, it is suggested that AST supplementation can improve weight gain and reduce feed conversion ratio. Lei and Kim (2014) [ 40 ] evaluated the effects of AST derived from Phaffia rhodozyma on performance and nutrient digestibility of finishing pigs. For this purpose, crossbred pigs (initial body mass approximately 58 kg) were treated with the addition of P. rhodozyma 0%, 0.1% or 0.2% , with an AST content of 2.305 mg/kg after when fermented and freeze-dried. The results showed that supplementation with P. rhodozyma improved feed efficiency and dry matter digestibility. Assessing the effect of increasing dietary astaxanthin (0, 5, 10 or 20 mg/kg) on the performance of late-finishing pigs [ 41 ], it was found that the growth performance of pigs was fed astaxanthin did not differ from control-fed pigs. Diet. In our study, astaxanthin was derived from Haematococcus pluvialis , which may explain the lack of significant change between groups compared to the study from which the AST was derived.Phaffia yeast . However, as shown in studies [ 42 , 43 ], diets containing 133 or 266 mg/kg of the alga Haematococcus pluvialis caused faster weight gain and significantly higher breast muscle mass and efficiency in broiler chickens. Feed utilization is higher in broilers. Perhaps the AST dose used in this study was too low to be effective in yield indicators.
4.2. Blood index
Although there were statistically significant differences between the groups, the hematological and biochemical indices in the blood were all within physiological norms [44], showing that the use of HI insecticide powder and astaxanthin did not affect the adversely affect the health status of weaned piglets. When studying the interaction between H. illucens powder and astaxanthin on hematological parameters, attention should be paid to the effects of these factors together and separately, because of the multicomponent nature of insect powder and its unique properties. Specific antioxidant and anti-inflammatory properties of insect powder. Astaxanthin will complement or exclude each other. In groups with higher lymphocyte concentrations than other groups, pigs showed no signs of disease and feeding parameters remained within normal limits. Similarly [ 30 ], it was found that inclusion of H. illucens powder in the diet did not significantly affect blood and serum parameters in pigs, but there was an increase in monocyte and white blood cell counts neutral when the level of this additive increases. . What was surprising in our study was the decrease in hemoglobin concentration in pigs treated with 5% HI larvae powder. Similarly, in the case of serum iron concentration, HI meal supplementation at both levels reduced this parameter. From a physiological point of view, this is harmful to the body, since the lower the hemoglobin concentration, the poorer the circulation of oxygen in the body and therefore the poorer the animal’s performance [ 45 ]. Lower serum iron concentrations in the HI larval powder only groups were reflected in red blood cell distribution width (RDWC; p < 0.01) and mean hemoglobin (MCH; p < 0.01 ). These results contrast with those [ 45 ] showing that replacing 25%, 50%, 75% or 100% fishmeal with HI meal did not worsen hematological parameters and RBC, HGB, HCT and RDW was even higher (however, p > 0.05) in the group supplemented with HI meals when compared with the control group. In their experiments, HI meal supplementation significantly reduced platelet count, whereas in the present experiment this parameter was not affected. The lipid fraction of Hermetia illucens larvae contains lauric acid in an amount of about 38.43% by weight [ 46 ]. It belongs to saturated fatty acids that aggravate dyslipidemia, and lauric acid increases circulating cholesterol levels contributing to cardiovascular disease [ 47]. In our experiments, supplementing the feed with 2.5 or 5% HI powder (36.5 g of lauric acid per 100 g of all estimated acids) did not affect blood cholesterol levels. In contrast, in the experiments of van Heugten et al. (2022) [ 34 ] where HI larvae oil (36.5–37.3 g lauric acid/100 g) was used at 2%, 4% or 6% in the feed, total cholesterol levels increased increased (about 17% compared to the control group) was the only significant effect observed in the biochemical blood indices of piglets. However, these authors did not observe any effect of lauric acid contained in HI oil on hematological parameters.
One mechanism of cardiovascular disease is erythema. Several studies have confirmed that lauric acid in human red blood cells stimulates erythropoiesis [ 47 ]. Additionally, the mechanism influencing erythema is oxidative stress [ 48 ], and this stress, according to the above study, is triggered by lauric acid [ 47 ]. Therefore, it can be assumed that in the present experiment, exposure to lauric acid, in the form of H. illucens powder supplementation, led to a decrease in the levels of selected erythrocyte parameters. Analyzing the results further, the beneficial effects of astaxanthin on these parameters (RBC, Fe, HCT, RDWC) were notable. Therefore, it can be assumed that astaxanthin partially prevents excessive oxidative stress that contributes to rosacea. The beneficial effect in limiting oxidative stress was confirmed in studies [ 49 ] in broiler chickens receiving 20 to 80 mg/kg AST, where increased catalase and superoxide dismutase concentrations were observed seen in plasma. Blood biochemical index studied by Yu et al. (2020) [ 36 ] on weaned piglets receiving 0%, 1%, 2% or 4% HI meals in feed. These authors observed that a 2% HI meal increased total protein, IL-10, and IgA while decreasing urea and triglyceride concentrations. In the present experiment, the concentrations of these biochemical indices were not affected by the addition of HI meal in the feed.
4.3. Analyze meat and back fat
In the experiment conducted, significantly higher TBARS values for meat ( longissimus m .) were observed in groups receiving astaxanthin and no effect of HI meal was observed after storage at −20 °C in 3 months. On the other hand, astaxanthin added to feed mixtures significantly reduced TBARS values in adipose tissue (back fat) stored under the same conditions. A significant interaction between experimental factors was also observed: the highest TBARS value for back fat was in the control group, while the most effective combination of dietary supplements for TBARS reduction was 2.5% of HI meal plus astaxanthin. The effectiveness of these supplements in improving the shelf life of lard was approximately 80% (2.5% HI meal group) and 77% (AST group and AST + 2.5% HI meal group) when compared with the control group. TBARS, expressed as malondialdehyde, is a valuable indicator of lipid peroxidation and oxidative susceptibility. It reflects the degree of oxidation: the higher the TBARS value, the stronger the lipid oxidation process. The beneficial effect of astaxanthin was observed in another study [ 50 ] when longissimus m. Ribs derived from pigs supplemented with astaxanthin had TBARS values more than 60% lower than ribs from control pigs after 7 days of retail exposure. Improvements in meat quality were also observed [ 49 ] in broilers fed 20, 40 or 80 mg/kg AST, which developed an antioxidant status in breast meat, reduced malondialdehyde levels and increased red and yellow flesh. These results suggest a beneficial effect of AST against lipid oxidation. This result is consistent with the antioxidant activity of AST, which protects membrane phospholipids and other lipids from peroxidation [ 51 ]. However, several studies [ 37 ] did not confirm any significant effect of 1.5 or 3 mg AST supplementation in feedlots on meat TBARS values, water loss, color meat and marbling value. This additive was fed to pigs for only 14 days, which may be too short a period to ensure significant meat quality and affect oxidative stability.
In the present experiment, the percentage of crude ash in pork treated with HI larvae powder was significantly lower. A similar result was obtained in another study, in which ash concentration in pectoral muscle in broiler chickens ( Pectoralis Major ) decreased linearly as the proportion of HI larval meal in the diet increased [ 52 ]. The authors attributed this result to the use of full-fat HI larvae powder, which was also used in our experiments.
5. CONCLUSION
The results of this study indicate that supplementation with full fat meal from H. illucens larvae and astaxanthin does not adversely affect feed intake and utilization, daily gain and organ weight in weaned piglets milk. Both factors, separately and interacting with each other, did not have a negative effect on biochemical and hematological blood parameters, which remained within the norm. It appears that astaxanthin supplementation even in small amounts supports the inhibition of oxidative stress, which becomes apparent in the case of certain red blood cell parameters. 2.5% full-fat H. illucens larvae meal and astaxanthin, used separately or together in feed mixtures, can reduce the susceptibility of weaned pigs to oxidation and improve expiry date. It has been suggested that higher concentrations (5%) of H. illucens powder should not be used because the presence of lauric acid may cause adverse changes in some red blood cell indices. However, consuming HI meals along with the antioxidant astaxanthin will improve these indicators.
