Reduction In Protein Digestibility Research Articles

Full-fat black soldier fly larvae meal and yellow mealworm meal: Impact on feed protein quality, growth and nutrient utilization of Atlantic salmon (Salmo salar) post smolts

The shift towards insect-based alternatives in aquafeeds stems from the need to reduce the carbon footprint associated with the ingredients used in salmon feeds. In the present study, we describe the effects of full-fat insect meal incorporation on amino acid derivatives in feeds and the growth performance and nutrient utilization of Atlantic salmon post-smolts fed insect meals. A 74-day growth trial was conducted employing 520 fish (143 ± 12.8 g); these fish were fed either a control diet (CO) that contained 20 % fishmeal, 20 % soy protein concentrate (SPC), 14 % wheat gluten, 19 % plant raw materials, 13 % fish oil and 6 % rapeseed oil, or one of four insect meal diets, prepared with either 5 % and 10 % black soldier fly larvae meal (BS5, BS10) or 15 % and 30 % mealworm meal (MW15, MW30), by substituting mainly SPC, wheat gluten and rapeseed oil. The inclusion levels of BS and MW were determined based on their distinct chemical compositions, specifically their lipid content. As regards the results, HPLC-based high-throughput data on amino acid derivatives revealed the following: carboxymethyllysine was significantly higher in the MW30 feed than in BS5, BS10 and MW15 feeds; carboxyethyllysine was higher in the MW15 and MW30 feeds compared to the others; furosine was lower in the MW15 feed compared to the CO, BS5 and MW30 feeds. Regarding the effect of the insect meals on Atlantic salmon post-smolts, their inclusion had no significant effect on feed conversion ratio, health indicators and the retention efficiency of macronutrients. Apparent digestibility coefficients (ADC) of dry matter, lipid, ash and energy were not significantly different. However, protein digestibility in the 30 % MW group (80.4 %) was significantly lower (P ≤ 0.05) compared to the control and BS5 group (84.5 %). Furthermore, the ADC of protein was found to decrease linearly with increasing levels of insect meals, with MW showing a significant relationship (adjusted r2 = 0.77, p = 0.014). Overall, our study highlights the efficacy of 5 and 10 % BS and 15 % MW as ingredients in the feeds of Atlantic salmon. Other focal points included the undesirable amino acid derivatives and a reduction in protein digestibility associated with 30 % of MW in the diet of Atlantic salmon. Hence, future investigations should focus on the effects of feed processing conditions on the protein quality of mealworm before suggesting higher inclusion levels to the feed industry.

A meta-analysis on the nutritional value of insects in aquafeeds

A major challenge for development of sustainable aquafeeds is its dependence on fish meal and fish oil. Similarly, it is unwanted to include more plant ingredients which adds more pressure on resources like arable land, freshwater and fertilisers. New ingredients that do not require these resources but rather refine and valorise organic side streams, like insects, are being developed. Increasing evidence indicates that using insect ingredients in aquafeeds are a sustainable alternative and considerable progress has been made on this topic in the past years. The aim of this chapter is to present a comprehensive and systematic analysis of the data available on the impact of insects in aquafeeds. Systematic search, collection and selection of relevant literature from databases such as Web of Science and NCBI was performed. The literature search enabled 91 scientific papers from peer-reviewed journals, comprising a dataset of 415 experimental diets, including 35 different aquatic species and 14 insect species to be included in this meta-analysis, covering what we consider a close to complete representation of credible publications on this topic. Information on aquatic species, insect species, dietary composition (amino acids, fatty acids, proximate composition) and performance outputs (growth performance indicators and nutrient digestibility) were included in the construction of the dataset. Regression models and principal component analyses were performed on the meta-data. The results from the meta-analysis revealed a great degree of variation in the maximum threshold for insect inclusion in aquafeeds (from 4 to 37%) based on subgroups of trophic level of aquatic species, insect species used, statistical method and the output parameter. Overall, a maximum threshold of 25-30% inclusion of insects in aquafeeds for uncompromised performance is suggested. Reduction in protein digestibility, imbalanced amino acid profile and increasing levels of saturated fatty acid were identified as major factors limiting higher inclusion of insects in aquafeeds.

Effect of domestic cooking methods on protein digestibility and mineral bioaccessibility of wild harvested adult edible insects.

Wild harvested edible insects are characterised by high protein and mineral contents with potential to contribute substantially to nutrition security. However, nutritional content is only beneficial when proteins are digestible and minerals bioaccessible. This study determined the effects of domestic processing on protein digestibility and mineral bioaccessibility of two wild harvested insect species: Eulepida mashona (beetle) and Henicus whellani (cricket). Samples of both insects were subjected to boiling, roasting, or combined boiling and roasting, imitating the way insects are traditionally prepared in Zimbabwe. Moreover, they were in vitro digested according to INFOGEST protocol. Boiling of both insects resulted in loss of protein as it leached into the boiling water. The raw insects had a higher protein in vitro digestibility than the boiled and roasted insects, and the maximal decrease in protein digestibility was around 25% for twice boiling of the beetles and for boiled and roasted crickets. For both insect species, boiling resulted in non-significant loss of iron and zinc. Iron was the least bioaccessible mineral in both insects, based on the concentrations of soluble mineral measured by ICP-AES. However, beetles had a much higher iron bioaccessibility (30.7%) as compared to crickets (8.11%). Interestingly, boiling resulted in about 50% decrease in iron and zinc bioaccessibility in both species while roasting did not. The reduced protein digestibility and mineral accessibility with processing can be explained by protein modification and interactions of minerals with other food components, such as chitin and phytochemicals. Because of the reduction in protein digestibility and mineral accessibility during boiling, roasting should be favoured over boiling and in any case short boiling time is recommended.

Nutritionally Enhanced Sorghum for the Arid and Semiarid Tropical Areas of Africa.

To help alleviate malnutrition in Africa, nutritionally enhanced sorghum was developed through genetic transformation to increase pro-vitamin A (β-carotene) accumulation and stability, to improve iron and zinc bioavailability, and to improve protein digestibility. Through many years of efforts, significant achievements have been made for these goals. We generated nutritionally enhanced sorghum lines with enhanced and stabilized pro-vitamin A that provide 20-90% of the Estimated Average Requirement (EAR) for children under age 3, lines with a 90% reduction in phytate that increase iron and zinc bioavailability and provide 40-80% of the EAR for iron and zinc, and lines that show no reduction in protein digestibility after cooking compared with normal levels. Once these nutritionally enhanced sorghum lines have undergone biosafety examination and have been deregulated, they will be ready for incorporation into sorghum varieties that will benefit Africa and other areas that rely upon sorghum as a staple food.

Effect of heat processing on selected grain amaranth physicochemical properties.

Grain amaranth is a pseudocereal with unique agricultural, nutritional, and functional properties. This study was undertaken to determine the effect of different heat-processing methods on physicochemical and nutraceutical properties in two main grain amaranth species, of Amaranthus hypochondriacus L. and Amaranthus cruentus L. Grains were prepared by roasting and popping, milled and analyzed for changes in in vitro protein digestibility, gruel viscosity, pasting characteristics, antioxidant activity, flavonoids, and total phenolics. In vitro protein digestibility was determined using the pepsin-pancreatin enzyme system. Viscosity and pasting characteristics of samples were determined using a Brookfield Viscometer and a Rapid Visco Analyzer, respectively. The grain methanol extracts were analysed for phenolics using spectrophotometry while antioxidant activity was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Heat treatment led to a reduction in protein digestibility, the effect being higher in popped than in roasted samples. Viscosities for roasted grain amaranth gruels were significantly higher than those obtained from raw and popped grain amaranth gruels. The results for pasting properties were consistent with the results for viscosity. In both A. hypochondriacus L. and A. cruentus L., the order of the viscosity values was roasted>raw>popped. The viscosities were also generally lower for A. cruentus L. compared to A. hypochondriacus L. Raw samples for both A. hypochondriacus L. and A. cruentus L. did not significantly differ in total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant activity values. Thermal processing led to an increase in TFC and antioxidant activity. However, TPC of heat-processed samples remained unchanged. From the results, it can be concluded that heat treatment enhances antioxidant activity of grain amaranth and causes rheological changes dependent on the nature of heat treatment.

Effect of trypsin inhibitor activity in soya bean on growth performance, protein digestibility and incidence of sub-clinical necrotic enteritis in broiler chicken flocks

1. The effect of three different levels of dietary trypsin inhibitor activity (achieved by varying the amount of non-toasted full fat soya bean in replacement for toasted full fat soya bean) on the incidence of spontaneously-occurring sub-clinical necrotic enteritis (NE) in broiler chickens was compared. A fourth dietary treatment compared the effect of a diet that used potato protein concentrate as the major protein source. The determined trypsin inhibitor activity increased with the increasing content of non-toasted soya bean: 1·90, 6·21, 8·46 and 3·72 mg/g for the three soya bean diets (0, 100 and 200 g of non-toasted soya bean/kg) and the potato protein diet respectively. 2. Although increasing amounts of the non-toasted full-fat soya bean increased the feed intakes of the birds, there was a marked reduction in protein digestibility, weight gain and feed conversion efficiency. 3. There was a linear increase in sub-clinical NE lesions in the duodenum, jejunum, mid small intestine and ileum with increasing non-toasted soya bean. Caecal Clostridium perfringens counts increased with the increasing dietary content of non-toasted soya bean. Serum α-toxin antibodies were higher in the birds fed the 200 g non-toasted soya bean/kg diet compared with the other diets. 4. The results demonstrated that variation in the amount of non-toasted dietary soya bean not only affects growth performance of broilers but also affects the incidence of sub-clinical necrotic enteritis in the flock. Ensuring the lowest possible trypsin-inhibitor activity in soya bean samples is a valuable tool to improve the health and welfare of birds and in reducing the financial losses from this disease.

Analysis of Quality Protein Changes in Nixtamalized QPM Flours as a Function of the Steeping Time

ABSTRACTThis study showed the protein changes in Quality Protein Maize (QPM H‐368C) during the traditional nixtamalization process as a function of the steeping time from 0 to 15 hr. Protein content (N × 6.25), pH, protein fractionation, reactive lysine, essential amino acids, and protein digestibility were analyzed to explain the protein quality modifications in nixtamalized corn flours (NQF). The thermoalkaline process increased significantly (P ≤ 0.05) the protein content (5.57 ± 0.86%) in NQF obtained at 3, 5, 7, 9, 11, 13, and 15 hr of steeping time compared with native corn or corn without treatment (NC). The pH values of NQF were not proportional to the steeping time and significantly different (P ≤ 0.05) between them. At 5 hr critical steeping time, the total lysine and reactive lysine content decreased severely (36 and 32%, respectively) with statistical differences (P ≤ 0.05) compared with NC. On the other hand, the tryptophan content decreased significantly (P ≤ 0.05) at steeping times of 5–15 hr (38.70 ± 6.7%) compared with NC. The changes in the lysine and tryptophan content were not proportional to the steeping time. The protein recovery in the albumin and globulin fraction diminished (P ≤ 0.05) with respect to raw corn. The protein recovery for γ‐zeins, glutelin‐like proteins, glutelins, and residue increased. A significant (P ≤ 0.05) decrease was found in the essential amino acids in NQF with 3–7 hr of steeping time compared with NC. Equally important was the reduction in protein digestibility observed in NQF steeped at long steeping times (11–15 hr) with significant (P ≤ 0.05) differences compared with NC. The protein solubility distribution along the steeping step and the essential amino acids location, specifically lysine in corn kernel, could explain partially the protein quality changes observed in this research. Finally, these results contribute to reconciling discrepancies associated with the protein quality modifications in nixtamalized corn reported previously in literature.

Effect of dehydroepiandrosterone on protein and fat digestibility, body protein and muscular composition in high-fat-diet-fed old rats

The main objective of the present study was to examine the effects of dehydroepiandrosterone (DHEA) on the digestive efficiency of dietary protein and fat. Second, we analysed the specific changes in muscle composition induced by the hormone. DHEA was given in the diet (0 x 5 %, w/w) to 75-week-old, high-fat-fed Sprague-Dawley rats (n 11) for 13 weeks; age- and weight-matched rats fed on the same diet without DHEA supplementation were used as controls (n 10). To determine dietary protein and fat apparent digestibility coefficients, 1-week 24 h faecal depositions were collected. In parallel, urine N was assessed. These assays were performed twice, in the short term (2-week treatment) and in the long term (13-week treatment). Body and gastrocnemius muscle compositions were also analysed. The present results show that DHEA decreased energy intake, body weight, body fat, adipocyte size and number (P<0 x 001). The feed efficiency ratio indicates that DHEA-treated rats were less efficient in transforming nutrients fed into their own biomass. Also, a short-term reduction in protein digestibility (P<0 x 05) and in body-protein degradation (P<0 x 01) was found in DHEA-treated rats, resulting in an increased content of body protein (P<0 x 05). Gastrocnemius muscles were smaller, as a result of fat (P<0 x 05) but not protein reduction. In conclusion, we confirm the slimming effect of DHEA and, for the first time, we demonstrate that DHEA has an effect at the digestive level. The anti-obesity properties of DHEA could be related to a reduction in protein digestibility in the short term and a protective effect on body protein with a selective mass loss from body fat.

Biological activity of polyphenol extracts from different plant sources

In experiments on rats, five diets without or supplemented with polyphenol extracts from different sources (flavons from skullcap, catechins from green tea, anthocyanins from chokeberry and condensed tannins from faba bean) were applied. Obtained results suggested that when catechin extracts were added to the diets in large amounts (0.8%), beneficial effects (reduction of total cholesterol and LDL fraction in serum) were observed, but also reduction in protein digestibility and protein efficiency ratio (from 94.6 to 93.1% and from 2.57 to 2.40, respectively), compared to the control group. All extracts decreased the activity of erythrocyte superoxide dismutase and increased the activity of alanine aminotransferase in the serum. Only the tannin extract decreased the content of calcium in femur. More profitable biological properties were found for catechin extract from green tea and flavons extract from skullcap, compared to anthocyanins from chokeberry and condensed tannins from faba bean.

An evaluation of co-extruded poultry silage and culled jewel sweet potatoes as a feed ingredient for hybrid Tilapia ( Oreochromis niloticus× O. mossambicus)

Two experiments were conducted with hybrid tilapia to evaluate a meal made by extrusion co-processing culled sweet potatoes and poultry mortality silage (ESPFP). In both experiments, dried, cull sweet potatoes and fermented whole turkey carcasses (60:40 ratio, w/w wet basis) were co-extruded, dried, and hammer-milled to make the ESPFP test ingredient. The resulting ESPFP meal was included at 0%, 11%, 22%, and 33% by weight in isocaloric, isonitrogenous pelleted diets. In an 87-day growth trial, no significant differences were found in the growth parameters or carcass (market) yields among the treatment groups. Tank water quality parameters were also unaffected by inclusion of the experimental ingredient. A consumer panel found no significant differences in the sensory indices (aroma, flavor, and texture) of the fillets from fish fed with the graded levels of ESPFP in the diet versus those from fish fed the control diet. The digestibility of the diets containing the ESPFP meal was evaluated in a second trial. The apparent dry matter (DM), gross energy (GE), and crude protein (CP) digestibility coefficients were reduced linearly with increasing levels of the ESPFP meal in the diets ( P<0.019). However, the level of inclusion of the ESPFP meal had no effect on the apparent organic matter (OM) digestibility coefficient values among the diets. Acid detergent fiber (ADF) and acid detergent insoluble nitrogen (ADIN) increased linearly ( P<0.001) with increasing levels of ESPFP in the diets, indicating significant heat damage had occurred during manufacture of the test ingredient. The indigestible Maillard polymers formed during extrusion co-processing and drying of these two ingredients accounted for 93% of the reduction in protein digestibility in the diets and were a contributing factor to the reductions in DM and GE digestibility. Extrusion co-processing of culled sweet potatoes and poultry mortality silage produces an acceptable feed ingredient for hybrid tilapia that can be included at up to 33% of the diet without adversely affecting growth, market yield, sensory indices, or water quality as compared to a standard tilapia diet.

Effects of dietary fiber and tannins on protein utilization in dry beans ( Phaseolus vulgaris)

The nutritional value of dry bean ( Phaseolus vulgaris) protein is typically lower than that of cereal and animal proteins, but the factors responsible for the low nutritional value of bean protein have not been clearly identified. In this study, the ability of dietary fiber and tannins to lower protein utilization in dry beans was investigated using weanling rats. The rats were fed eight experimental diets containing varying amounts of bean dietary fiber and tannins. Both protein digestibility and net protein ratio (NPR) were determined as measures of protein nutritional value. Soluble dietary fiber significantly increased fecal nitrogen losses ( P ≤ 0.001) and reduced protein digestibility ( P ≤ 0.001), while insoluble dietary fiber and tannins had no effect on either fecal nitrogen loss or protein digestibility. However, neither soluble nor insoluble dietary fiber had a significant effect on NPR, but tannins significantly reduced NPR values ( P ≤ 0.01). Both dietary fiber and tannins appear to contribute to the low nutritional value that is typical of bean protein, with soluble dietary fiber being primarily responsible for the reduction in protein digestibility that is commonly associated with dietary fiber in foods.

Antiherbivore Chemistry of Larrea Tridentata: Effects on Woodrat (Neotoma Lepida) Feeding and Nutrition

During winter, creosote bush (Larrea tridentata) dominates the diet of desert woodrats (Neotoma lepida) in the California Mojave Desert. The stems and leaves of creosote foliage are coated with large quantities of phenolic resins (10—25% of dry mass). We investigated whether woodrats feeding on creosote were influenced behaviorally by the resin and whether ingestion of creosote resin reduced the digestibility of protein as hypothesized by Rhoades and Cates (1976). Preference trials demonstrated that woodrats consistently selected creosote plant parts of low resin content. Removal of the resin with diethyl ether ameliorated this feeding preference and increased overall palatability of creosote foliage. Addition of the resin to laboratory chow ration caused this food to be avoided also. When woodrats were fed rations of creosote foliage or resin—treated laboratory chow no reduction in protein digestibility occurred. However, dry matter intake was reduced when woodrats were fed chow containing 12% resin. Our results indicate that creosote resin does deter feeding by desert woodrats. The antiherbivore mechanism of creosote resin to desert woodrats is likely one of toxicity and not digestibility reduction. This toxicity may limit the amount of creosote foliage woodrats can consume, which would explain the winter body mass decline and mortality that we observed in woodrats on our study site. We discuss the impact plant defense chemistry may have had on the evolution of Neotoma in the southwestern deserts of North America.

Effect of predigestion factors on the apparent digestibility of protein for swine determined by the Mobile Nylon Bag Technique.

Five Yorkshire x Lacombe barrows (45 kg initial wt) fitted with duodenal cannulas approximately 10 cm from the pyloric sphincter were used to determine the influence of the pH of the predigestion solution (pH 1.0, 1.5, 2.0 or 2.5), pepsin activity (189 vs 377 IU/liter) and duration of predigestion (0, 1.5, 2.5 or 4.0 h) on the apparent digestibility of the protein in soybean meal (SBM), meal and bone meal (MBM) or canola meal (CM) determined with the Mobile Nylon Bag Technique (MNBT). An additional six barrows were used to determine protein digestibility by conventional methods. Protein digestibilities determined using conventional digestibility techniques were 93.1 +/- .7, 79.1 +/- 1.8 and 79.3 +/- 1.4% for the SBM, MBM and CM diets, respectively. Protein digestibilities determined with the MNBT were highest at pH 2.0 for all three protein sources. Increasing pepsin activity from 189 to 377 IU/liter resulted in a slight increase in the digestibility of SBM and CM, but not of MBM. The absence of predigestion (0 h) resulted in a dramatic reduction in protein digestibility; predigestion times of 1.5 or 2.5 h usually resulted in lower protein digestibilities than did a predigestion time of 4.0 h. The closest agreement between results obtained by the MNBT and conventional digestibility studies occurred with a pH of 2.0, a predigestion time of 4.0 h and a pepsin activity of 377 IU/liter.

The Effect of Protein Levels on the Response of Weanling Rats to Dietary Pectin

We have previously proposed that the inhibiting effects of pectin on feed consumption and growth might be due in part to the reduction it causes in protein digestibility. The present work was intended to test this hypothesis by feeding higher levels of protein in order to compensate for the lower digestibility. We fed diets containing 10, 20 and 30% casein (initial levels) and 0, 4.8, 16.7 and 28.6% pectin (by diet dilution). Despite the higher casein levels, pectin strongly inhibited the animals' feed intake, growth, protein efficiency ratio (PER), net protein ratio (NPR) and net protein utilization (NPU) as well as protein and energy digestibilities. Apart from determining the base (zero pectin) level of the various parameters measured, the dietary casein level in itself did not influence the effect of pectin on feed intake, digestible energy intake, protein digestibility, body weight growth or parameters of protein utilization such as PER, NPR and NPU. We thus cannot conclude that these effects of pectin were to any major extent secondary to the reduction in protein digestibility observed in these animals.

DIGESTIBILITY OF PEA PROTEIN CONCENTRATE AND ENZYME-TREATED PEA FLOUR IN MILK REPLACERS FOR CALVES

In an experiment involving enzymatically hydrolyzed pea flour (HPF) and pea protein concentrate (PPC) to provide half the dietary protein in milk replacers, the pea protein was found to be about 25% digestible by calves under 2 wk of age and 65 to 70% digestible by calves 3 wk of age. The younger calves digested 42 to 53% of the pea starch; older calves digested 63 to 84%. The digestibility of dry matter, protein, energy and ether extract increased with calf age (P &lt; 0.01). In the second trial, involving PPC at 7.7, 15.4 and 23.1% of the dry matter in milk replacers, and providing 19, 33 and 46% of the dietary protein, the digestibility coefficients for dry matter, disregarding calf age, declined from 90 to 86% as PPC increased from 15.4 to 23.1%, but the low and intermediate PPC diets were equally well digested. The reduction was due mainly to the corresponding reduction in protein digestibility. Digestibility coefficients for dry matter, protein, energy, ether extract and nitrogen-free extract for milk replacer diets containing 23.1% PPC exceeded 81% with calves over 14 days old. The third experiment involved feeding the control milk replacer until the calves were 2 wk old, then commencing the feeding of PPC and HPF replacers, using formulas similar to those of the first experiment. The digestibility coefficients were similar to those of the first experiment, indicating that the observed improvement in older calves was primarily a function of calf age and not markedly influenced by the formula of the diet. These studies indicate that PPC and HPF are not satisfactory ingredients in milk replacers to be fed to calves under 2 wk of age, but, though less digestible than milk, are effectively digested thereafter.