Klaus Eder

This study evaluated the effects of partially (50%) or completely (100%) replacing soybean oil with Hermetia illucens larvae fat (HI fat) in diets for laying hens on productive performance, egg quality, yolk lipid composition, and ovarian follicle characteristics during a 20-week feeding period. Sixty Lohmann LSL Classic hens were randomly allocated to three dietary treatments (Control, HI50, and HI100; n = 20 hens per treatment). Due to space limitations within the experimental facility, each treatment was housed in a single pen, which precluded statistical analysis of production performance data. Nevertheless, descriptive evaluation revealed no obvious differences in laying rate, egg weight, egg mass, feed intake, or feed conversion ratio among the dietary treatments. Most egg quality traits, including albumen height, Haugh units, shell strength, and yolk color, remained unaffected, although minor transient differences were detected at individual sampling time points. Dietary treatments altered yolk fatty acid composition, reflecting the fatty acid profile of the experimental diets. Replacement of soybean oil with HI fat increased the proportions of saturated fatty acids, particularly lauric (C12:0), myristic (C14:0), and palmitic acids (C16:0), while reducing both n-6 and n-3 polyunsaturated fatty acids. In conclusion, the findings of this exploratory study indicate that HI fat may have potential as an alternative lipid source in layer diets. Under the conditions of the present experiment, no obvious adverse effects on productive performance, egg quality, or ovarian follicle characteristics were observed. However, because each dietary treatment was represented by a single pen, the results should be interpreted with caution and require confirmation in studies with replicated experimental units.

The gut microbiota is a metabolically active ecosystem that influences host physiology through bioactive metabolites and interactions with host signaling pathways. Recent research has established a bidirectional gut–muscle axis in which microbial metabolites and muscle-derived factors (myokines) regulate muscle protein synthesis, degradation, regeneration, fiber-type specification, and overall muscle performance. Studies using germ-free, antibiotic-treated, probiotic-supplemented, and fecal microbiota transplantation models demonstrate that the gut microbiota is a critical determinant of skeletal muscle mass and function. Key mediators include short-chain fatty acids, bile acids, aromatic amino acid metabolites, microbial-associated molecular patterns, and methylamine metabolites. This review summarizes current mechanistic knowledge of gut–muscle communication and its relevance to livestock production. In monogastric livestock, particularly pigs and poultry, microbiota transplantation experiments and targeted probiotic interventions provide causal evidence that gut microbial communities influence muscle growth, muscle fiber composition, intramuscular fat deposition, carcass traits, and meat quality, including tenderness, marbling, water-holding capacity, and flavor. Several studies have also identified specific microbial taxa and metabolites capable of transferring desirable production phenotypes. In contrast, evidence in ruminants remains largely associative and originates mainly from multi-omics and dietary intervention studies. Future research should validate causal mechanisms, identify robust microbial biomarkers, and develop species-specific microbiome-based strategies for precision livestock production.

The rearing of black soldier fly larvae represents a sustainable approach to organic waste valorisation and animal feed production. However, substrate composition is known to influence larval growth, nutrient assimilation and body composition. This study evaluated the effects of seven food industry by-products – carrot scraps, grape pomace, biscuit meal, bread crumbs, wheat bran, wheat pulp and rapeseed cake – compared to the standard Gainesville diet under commercial rearing conditions. Larvae were maintained in 144 containers (approximately 14 000 larvae per container) within a climate-controlled room. Each of the eight treatments was replicated 18 times, with six replicates harvested on days 4, 8 and 12 post-hatching for analysis. Substrate type significantly affected growth, survival and feed conversion, with interactions between substrate and harvest time ( ). Wheat bran yielded the highest survival rate, biomass gain and feed conversion efficiency, whereas carrot scraps and grape pomace resulted in the lowest values. Nitrogen retention was greatest in larvae fed wheat bran, while wheat pulp and rapeseed cake showed the lowest retention. Biscuit meal and bread crumbs improved energy retention compared to carrot scraps and grape pomace. Frass composition closely reflected substrate nutrient profiles, particularly nitrogen and energy content. Harvest timing also significantly influenced both larval and frass composition. These findings highlight the critical role of substrate selection in optimising nutrient utilisation, growth performance and biomass yield in BSFL production.

In most countries, male siblings of laying hybrids are culled immediately after hatching because their rearing is economically unfeasible due to low growth performance, poor feed efficiency, and a body composition unacceptable to consumers. In Germany, however, culling male day-old chicks has been prohibited for animal welfare reasons since 2022, making their rearing mandatory. Currently, no recommendations exist for protein and amino acid supply for these birds. This study aimed to determine the requirements for standardized ileal digestible (SID) methionine + cysteine (Met + Cys) and SID lysine (Lys) during the starter period (days 1–21) in male LSL Classic chicks by a dose–response approach. Two trials were conducted with 120 male chicks each, fed six diets containing SID Met + Cys concentrations ranging from 0.36% to 0.71% (Trial 1) or SID Lys concentrations ranging from 0.50% to 0.89% (Trial 2). Optimal concentrations were estimated using broken-line and exponential models based on body weight gain, feed intake, and feed conversion ratio. Considering all criteria, the optimal SID Met + Cys concentration was 0.58% (0.42 g/MJ AME_N), and the optimal SID Lys concentration was 0.74% (0.56 g/MJ AME_N). The calculated optimum SID Met + Cys:SID Lys ratio when standardized to an identical energy level was 74:100. These findings provide a basis for adjusting SID Met + Cys and SID Lys levels in starter diets for male chicks of a layer breed, supporting more efficient and sustainable rearing practices under current animal welfare regulations.

Previous studies have shown that insufficient phosphorus supply in dairy cows during the transition period can lead to postparturient hemoglobinuria, which is associated with the development of anemia and is presumably a consequence of increased osmotic fragility of erythrocytes. The exact causes of this condition remain unknown. The present study investigated the hypothesis that phosphorus depletion in dairy cows during the transition phase leads to changes in the phospholipid composition of the erythrocyte membrane, which may contribute to increased osmotic fragility. To test this hypothesis, an experiment with 18 healthy, multiparous, pregnant cows was conducted, in which cows received either a control diet with adequate phosphorus content (0.28% and 0.44% phosphorus in DM during the dry period and lactation, respectively, control group) or a diet with reduced phosphorus content (0.15% and 0.20% phosphorus in DM during the dry period and lactation, respectively, phosphorus depletion group) from 4 wk before expected calving until 4 wk postpartum. Blood samples were collected 2 wk before the expected calving date, as well as 1 and 4 wk postpartum. Erythrocyte membranes were isolated, and lipids were extracted for quantitative analysis of individual phospholipid species using liquid chromatography-MS. Phospholipid class contents (sphingomyelin, phosphatidylserine, phosphatidylethanolamine [PE], phosphatidylinositol, phosphatidylcholine [PC], lyso-PC, and lyso-PE) were not affected by the treatment. Similarly, the mean carbon atom chain length and the mean number of double bonds in individual phospholipids were not affected by treatment. There were very few changes of the percentages of individual phospholipid species. The time of sampling had only minimal effect on phospholipid composition and the proportions of individual phospholipid species. In conclusion, these results indicate that moderate and transient dietary phosphorus deprivation does not alter the phospholipid composition of the erythrocyte membrane. This suggests that phosphorus deprivation-induced periparturient hemoglobinuria is not caused by alterations in erythrocyte membrane lipid composition.

Previous studies have demonstrated that high-yielding dairy cows experience endoplasmic reticulum (ER) stress in the liver during early lactation. To date, most insights into the role of ER stress in metabolism and disease pathophysiology have been derived from rodent and human models. In dairy cattle, however, the specific impact of ER stress on metabolic pathways and its contribution to disease development remain insufficiently characterized. The objective of this study was therefore to investigate the molecular effects of ER stress using a bovine liver cell model (BFH12 cells). ER stress was induced by incubation with Tunicamycin (TM) and Thapsigargin (TG). Molecular responses to ER stress were assessed via a whole-genome array analysis and PCR targeting genes involved in selected metabolic pathways. Incubation with both ER stress inducers resulted in a marked upregulation of genes associated with the unfolded protein response (UPR) within a 4 to 24-h time frame, indicative of the production of robust ER stress in these cells. Unexpectedly, treatment with TM led to a downregulation of numerous genes involved in lipid biosynthesis, including those related to lipogenesis and cholesterol synthesis. Furthermore, incubation with TM and TG induced upregulation of genes involved in fatty acid oxidation and was accompanied by a reduction in intracellular triglyceride concentrations. Genes associated with inflammatory responses were upregulated by both TM and TG, whereas genes encoding antioxidant enzymes were downregulated. Genes involved in ketogenesis did not exhibit a consistent pattern of regulation. Overall, several effects of ER stress previously described in rodent models could not be replicated in this bovine liver cell system. Extrapolating these findings to dairy cows suggests that while ER stress may contribute to hepatic inflammation, it is unlikely to play a significant role in the development of hepatic lipidosis or ketosis.

By-products from winemaking, such as grape pomace, grape seeds, grape skins, or extracts made from them, represent a cost-effective and sustainable bioresource. These by-products are a source of polyphenolic compounds, plant fibers and—in the case of seeds—essential fatty acids with various health-promoting effects for livestock. Numerous studies involving fast-growing broiler breeds—which often suffer from metabolic inflammation and oxidative stress due to disproportionate breast muscle growth leading to issues like cardiorespiratory insufficiency—indicate that supplementing feed with grape by-products improves performance, particularly weight gain and feed efficiency. This literature review demonstrates that the performance-enhancing effects of grape by-products in fast-growing broiler breeds can be attributed to various mechanisms such as improved nutrient digestibility, a positive influence on intestinal morphology and integrity, the favorable modulation of the microbial community in the gut, the inhibition of oxidative stress or the enhancement of the antioxidant defense system, and the stimulation of the immune response.

High-yielding farm animals often face severe metabolic stress, compounded by environmental stressors such as psychosocial stress, heat stress, intensive housing systems, and poor hygiene management. These factors result in oxidative stress and inflammatory processes, which adversely affect both animal health and performance. Polyphenols are known to alleviate both oxidative stress and inflammatory responses. Since grapes are rich in polyphenols, by-products of winemaking could have beneficial effects on these processes. This review aims to provide an overview of the potential antioxidative and anti-inflammatory effects of grape by-products in farm animals. The first section of the review examines the causes and consequences of oxidative stress and inflammation. The second section highlights the general effects of polyphenols in addressing these issues. The third and central part of the review presents an overview of findings from studies investigating the impact of various grape-derived polyphenols on the antioxidant system and inflammation in pigs, chicken, and cattle. Overall, these studies demonstrate that grape by-products can effectively reduce oxidative stress and inflammation in pigs and chickens, often leading to improved performance. In cattle, however, fewer studies have been conducted, and the results regarding oxidative stress and inflammation are less consistent. In conclusion, grape by-products represent valuable feed options for preventing oxidative stress and inflammation in monogastric farm animals (pigs, chickens).

Black soldier fly, H. illucens larvae, efficiently convert low-value organic substrates into high-value products, offering solutions to global challenges in sustainable food production and biotechnology. This study investigated the impact of dietary protein levels (10%, 14%, 16%, and 20% crude protein, CP) on BSFL growth, nutrient utilization, and energy retention using isoenergetic diets (18.5 ± 0.3 MJ/kg dry matter) under commercial-scale conditions. Larvae were harvested after 8 days of feeding, with 5 replicates per treatment. Optimal growth performance and feed conversion ratios were observed in larvae fed 14% CP diet, with a quadratic relationship between dietary CP and biomass gain (p < 0.001, R² = 0.870). Ash and calcium deposition peaked in CP20-fed larvae and were lowest in CP14-fed larvae. Phosphorus and glucosamine deposition remained unaffected, while chitin deposition correlated positively with larval weight. Nitrogen and amino acid retention were highest in CP14-fed larvae but reduced in CP20-fed larvae (p < 0.001, R² = 0.573–0.902). CP10-fed larvae showed impaired growth and nitrogen deposition but increased fat deposition. These findings establish the CP14 diet as the optimal formulation for scalable BSFL production, providing critical insights into dietary protein effects on BSFL physiology and enabling the development of efficient feeding strategies for industrial-scale farming.