Amino Acid Digestibility of Different Formulations of Torula Yeast in an In Vitro Porcine Gastrointestinal Digestion Model and Their Protective Effects on Barrier Function and Inflammation in a Caco-2/THP1Co-Culture Model.

Single-cell protein from torula yeast (Cyberlindnera jadinii) grown on lignocellulosic biomass has been proven to be an excellent alternative protein source for animal feed. This study aimed to evaluate the amino acid (AA) digestibility by estimating intestinal absorption from three yeast-based ingredients, produced by cultivating C. jadinii on hydrolysate, using either mixed woody species (drum- (WDI) or spray-dried (WSI)) or corn dextrose (drum-dried (DDI)) as the carbon source. Further, the protective effect of intestinal digests on activated THP1-Blue™-induced epithelial damage and cytokine profile was evaluated. Total protein content from these three ingredients ranged from 34 to 45%, while the AA dialysis showed an estimated bioaccessibility between 41 and 58%, indicating good digestibility of all test products. A protective effect against epithelial-induced damage was observed for two of the three tested products. Torula yeast cultivated on wood and drum-dried (WDI) and torula yeast cultivated on wood and spray-dried (WSI) significantly increased transepithelial electrical resistance (TEER) values (111-147%, p < 0.05), recovering the epithelial barrier from the inflammation-induced damage in a dose-dependent manner. Further, WSI digests significantly reduced IL8 (250.8 ± 28.1 ng/mL), IL6 (237.9 ± 1.8 pg/mL) and TNF (2797.9 ± 216.3 pg/mL) compared to the blank control (IL8 = 485.7 ± 74.4 ng/mL, IL6 = 478.7 ± 58.9 pg/mL; TNF = 4273.5 ± 20.9 pg/mL) (p < 0.05). These results align with previous in vivo studies, supporting torula yeast-based ingredients as a high-quality protein source for pigs, protecting the intestinal barrier from inflammatory damage, and reducing the pro-inflammatory response. We provided novel insights into the mechanisms behind the health improvement of pigs fed on torula yeast-based ingredients, with potential applications for designing nutritional interventions to recover intestinal homeostasis during critical production periods, such as weaning.

Evaluation of 30% DAS-444Ø6-6 soybean meal in a subchronic rat toxicity study.

Event DAS-444Ø6-6 soybean is genetically modified (GM) to provide tolerance to 2,4-diclorophenoxyacetic acid (2,4-D), glyphosate, and glufosinate herbicides through expression of the AAD-12, 2mEPSPS, and PAT proteins, respectively. DAS-444Ø6-6 soybeans were evaluated for safety in subchronic rat feeding studies. The results from two previous subchronic rat feeding studies evaluating diets formulated with 20% inclusion of DAS-444Ø6-6 soybean meal (the latter also containing DAS-444Ø6-6 derived hulls and oil) did not show any treatment-related adverse effects. In 2017, to comply with recent guidance from EFSA, a third 90-day rat feeding study was conducted with Sprague-Dawley rats (16/sex/group) with diets formulated either with 15% or 30% w/w of toasted DAS-444Ø6-6 soybean meal. DAS-444Ø6-6 soybean hulls and oil were also added to the transgenic test diets at 1% or 2% w/w and 1.35% or 2.7%, respectively, for the low- and high-dose groups. No toxicologically significant effects were observed under the conditions of this study.

Food and feed safety of DAS-444Ø6-6 herbicide-tolerant soybean.

DAS-444Ø6-6 soybean was genetically engineered (GE) to withstand applications of three different herbicides. Tolerance to glufosinate and glyphosate is achieved through expression of the phosphinothricin acetyltransferase (PAT) and double-mutated maize 5-enolpyruvyl shikimate-3-phosphate synthase (2mEPSPS) enzymes, respectively. These proteins are expressed in currently commercialized crops and represent no novel risk. Tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) is achieved through expression of the aryloxyalkanoate dioxygenase 12 (AAD-12) enzyme, which is novel in crops. The safety of the AAD-12 protein and DAS-444Ø6-6 event was assessed for food and feed safety based on the weight of evidence and found to be as safe as non-GE soybean.

Allergenic potential of novel proteins - What can we learn from animal production?

Currently, risk assessment of the allergenic potential of novel proteins relies heavily on evaluating protein digestibility under normal conditions based on the theory that allergens are more resistant to gastrointestinal digestion than non-allergens. There is also proposed guidance for expanded in vitro digestibility assay conditions to include vulnerable sub-populations. One of the underlying rationales for the expanded guidance is that current in vitro assays do not accurately replicate the range of physiological conditions. Animal scientists have long sought to predict protein and amino acid digestibility for precision nutrition. Monogastric production animals, especially swine, have gastrointestinal systems similar to humans, and evaluating potential allergen digestibility in this context may be beneficial. Currently, there is no compelling evidence that the mechanisms sometimes postulated to be associated with allergenic sensitization, e.g. antacid modification of stomach pH, are valid among production animals. Furthermore, examples are provided where non-biologically representative assays are better at predicting protein and amino acid digestibility compared with those designed to mimic in vivo conditions. Greater emphasis should be made to align in vitro assessments with in vivo data.

Stacking transgenic event DAS-Ø15Ø7-1 alters maize composition less than traditional breeding.

The impact of crossing ('stacking') genetically modified (GM) events on maize-grain biochemical composition was compared with the impact of generating nonGM hybrids. The compositional similarity of seven GM stacks containing event DAS-Ø15Ø7-1, and their matched nonGM near-isogenic hybrids (iso-hybrids) was compared with the compositional similarity of concurrently grown nonGM hybrids and these same iso-hybrids. Scatter plots were used to visualize comparisons among hybrids and a coefficient of identity (per cent of variation explained by line of identity) was calculated to quantify the relationships within analyte profiles. The composition of GM breeding stacks was more similar to the composition of iso-hybrids than was the composition of nonGM hybrids. NonGM breeding more strongly influenced crop composition than did transgenesis or stacking of GM events. These findings call into question the value of uniquely requiring composition studies for GM crops, especially for breeding stacks composed of GM events previously found to be compositionally normal.

Comparative performance of broilers fed diets containing DAS-44406-6 and non-transgenic soybean meal.

Broiler chickens are fast growing monogastric animals considered a sensitive test species to evaluate the safety and nutritional equivalence between transgenic and non-transgenic grains as part of the human safety evaluation process. DAS-44406-6 soybean expresses three herbicide-tolerant proteins: the aryloxyalkanoate dioxygenase-12 (AAD-12) enzyme which provides tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides, the double-mutant 5-enolpyruvylshikimate-3-phosphate synthase (2mEPSPS) enzyme encoded by a modified version of the epsps gene from maize (Zea mays), which provides tolerance to glyphosate herbicides, and the phosphinothricin acetyltransferase (PAT) enzyme from Streptomyces viridochromogenes, which provides tolerance to glufosinate herbicides. A 42-day broiler study was conducted with diets containing toasted DAS-44406-6 soybean meal to evaluate nutritional wholesomeness and safety compared with non-transgenic, near-isoline soybean and conventional comparators. The study used a randomized complete block design with five dietary treatments assigned randomly within six blocks of 12 pens per treatment, with 10 birds per pen. Broiler performance and carcass parameters were measured over a 6-week period of exposure to diets containing different sources of toasted soybean meal and hulls. Among the 13 endpoints measured, only thigh weight was numerically different between birds fed DAS-44406-6 soybean meal and those fed isoline soybean meal. However, no significant differences to thigh weight were observed between birds fed DAS-44406-6 soybean and any of the non-transgenic reference varieties. Results indicate that DAS-44406-6 soybeans are nutritionally equivalent to conventional varieties.

The effects of age, energy and protein intake on protein turnover and the expression of proteolysis-related genes in the broiler breeder hen.

A study was conducted to determine the changes that occur to proteolysis and related genes due to age, protein, and energy intake in high-yield broiler breeder hens (Gallus gallus). Cobb 700 broiler breeders were randomly assigned to one of six diets in a 2×3 factorial fashion. Two levels of energy (390 and 450 kcal/day) and three levels of protein (22, 24, and 26 g CP/day) were utilized. Protein turnover was determined in the left pectoralis at 22, 26, 31 and 44 weeks. Relative mRNA expression of calpain 2 (CAPN2), proteasome C2 subunit (PSMA1), and F box protein 32 (FBXO32) were determined via RT-PCR at 20, 25, and 44 weeks. Contrasts indicate fractional synthesis rate (FSR) and FBXO32 increase to a maximum at 25-26 weeks and a decrease thereafter. A significant drop in PSMA1 and FBXO32 was observed between 25 and 44 weeks and matched the decrease observed in FBR. No differences were detected in the levels of fractional synthesis and degradation, or the expression of CAPN2, PSMA1, and FBXO32, due to protein or energy intake. In summary, protein turnover was upregulated during the transition into sexual maturity and decreased thereafter. The observed changes in degradation appeared to be mediated by the ubiquitin-proteasome pathway.