Abstract Insect proteins represent a promising and more sustainable alternative to soybean meal in swine nutrition. However, high dietary inclusion levels often result in reduced animal performance, indicating that factors other than crude protein concentration should be considered. This study evaluated the protein quality and degradability of feed-grade defatted black soldier fly (BSF) meal in comparison with a conventional organic protein core for post-weaning piglets. Protein content, amino acid composition, reactive lysine, Maillard reaction markers, buffering capacity, and protein hydrolysability were determined. Our results showed that defatted BSF meal exhibited a protein content and amino acid profile comparable to those of the protein core but contained substantially higher levels of free amino acids. Accounting for free amino acids reduced the estimated lysine damage from 18.41% to 10.87%, highlighting the importance of considering free amino acids when determining reactive lysine. In addition, BSF meal exhibited a higher buffering capacity and lower protein degradability than the protein core. These findings provide new insights into the nutritional limitations of feed-grade BSF meal and suggest that a more accurate assessment of reactive lysine, together with dietary strategies to reduce buffering capacity, may improve its utilization in post-weaning piglet diets.

A major growth performance trait of modern-day broiler chickens is the ability to attain a high body weight (BW) within a short time. Here we identified parameters or factors significant associated with higher broiler BW using data on tissue (blood, jejunum, ileum and caecal tonsil) transcriptome, ileal and caecal digesta microbiota and metabolome, and blood biochemical and immune parameters. The data originated from 35-day-old Ross 308 male broilers reared under practical housing conditions and fed a non-starch polysaccharide-rich diet supplemented with either a probiotic or a postbiotic, including or not their carriers. Omics data were available for 72 broilers which were a subset of the 160 birds for which blood biochemical and immune parameters were available. The distribution of the BW did not significantly deviate from normality within the treatment groups and overall. Among all datasets, the jejunal tissue transcriptome was most associated with differences in broiler BW. Notably, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with inflammatory response were significantly (p < 0.05) enriched in broilers with a low BW (e.g. Toll- and NOD-like signaling, phagosome, cytokine-cytokine receptor interaction, and cytosolic DNA sensing pathways) while gene ontology (GO) pathways associated with a response to toxic substances and anti-oxidative defenses were enriched in birds with high BW. In caecal tonsil tissue, broilers with a higher BW had pathways related to the immune response enriched (KEGG: cytokine-cytokine receptor interaction; GO: immune system process and response) with minor changes observed in their microbiota. Broiler BW was mainly associated with the tissue transcriptome, especially jejunum. In broilers with a higher BW, decreased expression of inflammation and increased expression anti-oxidative defense pathways were observed in jejunal tissue, while the caecal tonsil tissue showed a higher expression of immune pathways. Reducing inflammation and increasing anti-oxidative defenses in the proximal small intestine of broilers may provide future targets for improved broiler growth.

To promote growth performance and health of broiler during production, additives, like pro-and postbiotics, are often used and most of them use carriers. This study aimed to investigate if carriers can modulate the physiological effects of two lactobacilli-based pro-(Pro) and postbiotic (Post) additives, and to gain more insight into their physiological effects in the absence of carriers, in broilers fed a non-starch polysaccharide-rich diet reared under practical housing conditions. A total of 1600, one-day-old male Ross 308 chicks were equally distributed among 5 treatments (control, Pro and Post with and without their respective carriers) with 8 replicate pens each and 40 broilers/pen. Growth performance parameters, footpad lesions, and blood plasma physiological parameters related to nutrition and immunity were determined. On d35, Pro increased body weight (BW) (+2.1 %; p = 0.025), while its carrier negated this effect (-1.9 %; p = 0.047). Post did not affect d35 BW but increased the feed conversion ratio (FCR) by 1.3 % (p = 0.041), while its carrier increased BW (+2.4 %; p = 0.013), and lowered FCR (-1.3 %; p = 0.042). Growth performance parameters showed a beneficial effect of Pro but not Post, while the use of their respective commercial carriers had a growth-depressing and-promoting effect, respectively. Carriers also affected the footpad lesion score, and blood parameters related to nutrition and immunity. These results highlight that additive carriers can modify the effects on broiler growth and metabolism of the pro-and postbiotic additives to which they are added. The occurrence of an additive-carrier interaction indicates that carriers for pro-and postbiotic additives for broilers must be carefully selected.

Protein fermentation in the human gut is often associated with adverse health effects. Hence, understanding the fermentation characteristics of dietary undigested proteins is important for a comprehensive nutritional value of foods. This study investigated the protein fermentation kinetics of diet-derived proteins from thirty-one different foods using an in vitro model and human faecal inoculum. The undigested diet-derived protein substrate originated from porcine ileal digesta obtained from assessment of the digestible indispensable amino acid score (DIAAS) of the foods. Significant variations in fermentation kinetic parameters, particularly in maximum gas production rate (Rmax) and time to reach cumulative gas production (GP) from the substrate (TGPs), were observed. The Rmax ranged from 15·5 (se 0·7) ml/h for wheat bran-derived to 24·5 (se 0·9) ml/h for oatmeal-derived proteins. Egg-derived proteins had the shortest TGPs (14·7 (se 0·7) h), while mushroom-derived proteins had the longest (27·6 (se 7·1) h). When foods were categorised into five groups ('animal protein', 'grains', 'legumes', 'fungi, algae and microorganisms' and 'others'), no significant differences were found in fermentation kinetics parameters. Samples were additionally incubated with porcine inoculum to assess potential donor-species effects. Human inoculum showed significantly lower Rmax, cumulative GP and microbiota turnover than porcine inoculum, indicating reduced fermentative activity. Linear regression analysis revealed correlations between human and porcine-derived inoculum only for Rmax (R2 = 0·78, P < 0·01) and TGPs (R² = 0·17, P < 0·05). These findings underscore the importance of using human inoculum in in vitro studies to better predict health implications of foods with DIAAS values.

Diets rich in non-starch polysaccharides (NSP) are known to challenge broiler growth and induce gut inflammation. Here, a lactobacilli-based probiotic (Pro) and its derived postbiotic (Post) were investigated when supplemented to an NSP-rich challenge diet (Ctrl) fed to broilers reared under commercial conditions. Treatments had 8 pen replicates with 40 broilers each. On day 35, for 3 broilers/pen, the microbiota, volatile fatty acids and semi-polar metabolome composition were determined in ileal and caecal digesta. In addition, changes in the transcriptome of jejunal, ileal and caecal tonsil tissues as well as in the blood were investigated by RNA-seq. Apparent ileal nutrient digestibility and tibia health were also assessed. The Pro affected the relative abundance of four operational taxonomic units (OTU) in ileal and none in caecal digesta. The Post affected the relative abundance of nine OTU in ileal and two in caecal digesta. Microbiota diversity indexes and the semi-polar metabolome were not affected by Pro and Post. According to gene set enrichment analysis of Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, the jejunal tissue transcriptome of Pro v.s. Ctrl birds had upregulated pathways linked to cell activity, energy production and DNA transcription. In ileal tissue, similar pathways had a significant enrichment score. In jejunal tissue, downregulated pathways with Pro were linked to immunity and inflammation. In caecal tonsil tissue, Pro was associated with a negative enrichment score of immune and detoxification-related pathways in KEGG and GO. The Pro had minor effects on the blood transcriptome. Compared to Ctrl, Post had minor effects on the jejunal, ileal and caecal tonsil tissues transcriptome, and no effects on the blood transcriptome. Overall, Pro and Post elicited different physiological effects with Pro but not Post supplementation inducing a clear pattern of potential mechanisms. Results indicate that the lactobacilli-based probiotic induced beneficial effects by lowering inflammation in the gut, and that these effects likely originate from the more proximal intestine.

BACKGROUND:A Food and Agriculture Organization Expert Consultation recommended the use of digestible indispensable amino acid score (DIAAS) to evaluate protein quality of foods for humans. Calculation of DIAAS requires true ileal digestibility (TID) of amino acid (AA) values but currently insufficient data are available. OBJECTIVES:This study aims to generate in pigs TID of AA for a wide range of foods commonly consumed by humans and determine the range of differences in TID of AA among food types. METHODS:A standardized protocol was followed to determine TID of AA in 97 foods across 3 laboratories. Female pigs (25-100 kg during study, n ≥ 6) received foods for 7 d following a Youden Square design with ileal digesta collected via T-cannula on days 6-7. Endogenous AA losses were determined by feeding a protein-free diet. Foods, diets, and digesta were analyzed for nitrogen, AA, reactive lysine, titanium and dry matter. Foods were categorized into food types with the degree of variation within each food type evaluated using descriptive statistics. RESULTS:The TID (mean of AA) ranged from 0.247 (apples) to 0.988 (beef tenderloin). The median TID of AA was high (mean of AA > 0.90) for foods categorized as dairy products, eggs, fish and seafood, isolates and concentrates, meat, nuts, plant-based burgers, soy products and wheat products. Food categories with median TID < 0.80 were baked products, fruit, pulses and seeds, and wheat bran cereal, yeast, and zein. Food categories with low variations between foods were fish and seafood (1% units), dairy products (3% units), and eggs (5% units), whereas categories with the greatest variation were grains (18% units), vegetables (16% units), seeds (14% units), and fruit (12% units). There was considerable variation in TID for individual AA both within and among foods. CONCLUSIONS:The database with TID of AA of 97 foods generated by 3 laboratories using a standardized methodology can be utilized for protein quality evaluation.

This study aimed to investigate the in vitro fermentation potential of ileal digesta from pigs fed 7 protein sources with different batches-maize germ meal (MGM), cottonseed meal (CSM), rapeseed cake (RSC), rapeseed meal (RSM), peanut meal, soybean meal (SBM), and sunflower meal (SFM)-to assess their potential impact on hindgut protein fermentation, which can be harmful to animals. Ileal digesta samples were incubated with porcine fecal inoculum under N-free conditions, with whey protein isolate (WPI) as a control. Gas production (GP) resulting from protein fermentation was monitored over 48 h and analyzed using a modified biphasic model to assess substrate fermentation and microbiota turnover dynamics. Significant variations in fermentation characteristics, including maximum GP rates (Rmax), cumulative GP, and microbiota turnover slopes, were observed across the protein sources. Rmax values ranged from 16.8 ± 0.6 to 27.9 ± 0.8 mL/h for MGM and SFM, respectively compared to 12.5 ± 0.4 mL/h for WPI. Solubility and molecular mass analyses showed differences in the proportion of insoluble nitrogenous molecules and the distribution of soluble molecules, reflecting varying fermentability. Standardized hindgut fermentation potential differed significantly among the protein sources, with MGM exhibiting the highest potential (1.18 L/g dietary protein) and SBM the lowest (0.46 L/g dietary protein). These findings provide valuable insights into the differential accessibility of undigested protein to hindgut microbiota, contributing to more effective diet management and optimization of animal and human nutrition strategies.

In-home palatability testing of cat foods has the benefit of producing outcomes that are highly representative for the target pet population. Here, we determined the minimal in-home cat food palatability study duration and sample size. Privately-owned cats participated in either a one-bowl acceptance test (14 female,18 male; 6.2 f 4.6 yr; 4.5 f 1.3 kg) or two-bowl preference test (13 female, 17 male; 5.9 f 3.3 yr; 4.3 f 1.1 kg) where they were provided two complete extruded dry foods. The two foods provided were formulated to contain either a high (food HHP and HLP) or low contrast (food LHP and LLP) in palatability. The one-bowl test was done in a cross-over design. Feeding periods for both tests were 10 days and food leftovers were weighed daily to assess test food intake. Food intake percentages (one-bowl) and ratios (two-bowl) were analyzed across days using repeated measures ANOVA with post hoc Tukey tests. Bootstrap sampling was used to assess the impact of increasing the number of test days and sample size on the precision of the food intake estimates. There were no significant differences across days in one-bowl food intakes nor two-bowl intake ratios regardless of foods indicating that one test day suffices. More test days did reduce variation in the food intake measurements, thus increasing precision, but decreased test accuracy as cats with low food intake became missing values when dropping out of the study population. Increases in sample size increased precision, and the required number of cats for reliable outcomes varied between foods, food intake measurements and chosen margin of error. When implementing a margin of error of 10 %, sample sizes would range from 12 to 43 cats in one-bowl trials, depending on the food in the acceptance test, and 17-23 cats in two-bowl trials, depending on the contrast in palatability between the foods in the preference test. The development of protocols for in-home palatability testing of cat foods may progress further by identifying and controlling sources of variation in the cats' food intakes as a means to increase the precision of measurements.

Understanding protein fermentation in the hindgut of pigs is essential due to its implications for health, and ileal digesta is commonly used to study this process in vitro. This study aimed to assess the feasibility of utilising in vitro digested residues as a replacement for ileal digesta in evaluating the protein fermentation potential. In vitro residues from cottonseed meal, maize germ meal, peanut meal, rapeseed cake, rapeseed meal, soyabean meal and sunflower meal were analysed using a modified gas production (GP) technique and curve fitting model to determine their fermentation dynamics and compare with the use of ileal digesta. Significant variations were observed in GP parameters between in vitro digested residues, indicating differences in nitrogen utilisation by fecal microbiota. Soyabean meal and sunflower meal exhibited the highest maximum GP rates (Rmax), with values of 29·5 ± 0·6 and 28·0 ± 1·2 ml/h, respectively, while maize germ meal showed slowest protein utilisation (17·3 ± 0·2 ml/h). A positive relationship was found between the Rmax of in vitro residues and ileal digesta (R2 = 0·85, P < 0·01). However, GP potential (GPs) showed a tendency for a negative relationship (R2 = 0·39, P < 0·1), likely due to narrow observed GPs values and the presence of varied endogenous proteins in ileal digesta. Our results demonstrate the potential of using in vitro digested residues as a substitute for ileal digesta in assessing the fermentation potential of protein ingredients, particularly regarding the rate of protein fermentation.

Lactobacillus rhamnosus CNCM I-3698 (LR98) and L. formosensis CNCM I-3699 (LF99) are two probiotic bacterial strains used in industry in a co-fermentation process to produce a probiotic (Pro) and the associated postbiotic (Post). The latter is produced through inactivation of the viable cells in the Pro by a high-temperature short-time (HTST) treatment. The impact of the inactivation process on the metabolomic profile of the Post was investigated. A growth substrate (Control) was fermented using a co-culture of LR98 and LF99 to produce the Pro and then HTST treated (~105 °C; 5 bar; 7 s) to derive the Post. Analysis of the semi-polar metabolome yielded 1412 unique features, from which 105 compounds were identified. The HTST process decreased the peak area in the Post of most features by <10%. Due to fermentation, an increase (fold change > 2; adjusted-p < 0.05) in the peak area was observed for 29 identified compounds, including 15 with known immunomodulatory, anti-oxidative or antibacterial property. The HTST treatment decreased the peak area of 4 of these compounds by >10% and 25 compounds by <10%. The HTST treatment to yield the Post induced minimal changes in the metabolomic profile, while the fermentation to produce the Pro yielded metabolites with known biological activity.

Housefly (Musca domestica L.) larvae can convert animal manure into valuable protein and fat but little is known about their nutritional requirements. We assessed the effects of differential starch content in unsterilised (UE) and heat sterilised (SE) chicken excreta on larval performance and bioconversion. Gelatinized corn starch was added to excreta resulting in 11 diets with 0 to 50% starch of dry mass. Individual larval mass increased from (mean +/- SD) 12 +/- 0.2 (UE) and 13 +/- 0.4 (SE) mg at 0% starch up to 18 +/- 0.4 (UE) and 18 +/- 0.5 (SE) mg at 15% starch and decreased to 5 +/- 0.4 (UE and SE) mg in 50% starch. Higher starch concentrations resulted in non-normal distributions of individual larva mass. Larval wet yield showed a curvilinear relation with starch content, with maxima of 39 +/- 2.3 g in UE at 10% starch, and 43 +/- 2.8 g in SE at 15% starch. The decrease in yield after the maxima was faster in UE compared to SE. Larval survival was highest in 0% starch, 80 +/- 8% (UE) and 72 +/- 13 % (SE), linearly decreasing to 14 +/- 7% (UE) and 18 +/- 3% (SE) in 50% starch. Dry matter bioconversion increased from 4 +/- 0.1% (UE) and 4 +/- 0.3% (SE) in 0% starch to 6 +/- 0.2 in UE with 10% starch and 7 +/- 0.3 in SE with 15% starch, decreasing to close to 0 in 50% starch. Highest nitrogen bioconversion was 15 +/- 0.5% in UE with 10% starch and 15 +/- 0.5% in SE with 15% starch. Optimal starch inclusions increased nitrogen bioconversion with 40% (UE) and 100% (SE) compared to pure excreta. Finally, around 20 to 25% starch uric acid and ammonia contents, pH, and diet residue C/N decreased, indicating a tipping point. In conclusion, adding starch to chicken excreta can substantially increase larval yield and bioconversion while reducing ammonia content in the substrate residue.

White rot fungi can degrade lignin and improve the nutritional value of highly lignified biomass for ruminants. We screened for excellent fungi-biomass combinations by investigating the improvement of digestibility of wheat straw, barley straw, oat straw, rapeseed straw, miscanthus, new reed, spent reed from thatched roofs, and cocoa shells after colonisation by Ceriporiopsis subvermispora (CS), Lentinula edodes (LE), and Pleurotus eryngii (PE) (indicated by increased in vitro gas production [IVGP]). First, growth was evaluated for three fungi on all types of biomass, over a period of 17 days in race tubes. CS grew faster than LE and PE on all types of biomass. LE did not grow on cocoa shells, while growth rate of CS and PE on cocoa shells was lower compared to other types of biomass. After this first screening, all types of biomass, excluding the cocoa shells, were colonised by the three fungal strains for 8 weeks. Treatment with CS and LE improved IVGP more than treatment with PE. Methane production was reduced in six combinations of biomass with CS, four with LE, and three with PE. Six types of biomass were selected for treatment with CS and four were selected for treatment with CS and LE, to determine the net improvement of nutritional value (increased IVGP corrected for dry matter loss) after 2, 4, 6, 7 and 8 weeks of treatment. The highest net improvement was found for CS and LE treated rapeseed straw (86% and 20%, respectively) and spent reed (80% and 43%, respectively). All treatments decreased dry matter, lignin and hemicellulose, the latter two both in absolute amount and content. In conclusion, net improvement of highly lignified biomasses by CS was greater than LE, with the nutritional value of rapeseed straw and spent reed being significantly improved by both fungi.

BACKGROUND:When determining true ileal amino acid (AA) digestibility values in the growing pig to calculate digestible indispensable AA score, there are aspects of the protocol, both genetic and environmental, that vary between laboratories. OBJECTIVES:This study aimed to determine true ileal AA digestibility in 9 foods in each of 3 laboratories (Australasia, Europe, and North America) to determine interlaboratory variability. In each laboratory, 3 foods were also evaluated twice to determine intralaboratory variation. METHODS:Each laboratory followed a standardized protocol to determine true ileal AA digestibility for each food. Growing pigs received each food for 7 d and digesta were collected via a cannula at the terminal ileum on days 6 and 7. True ileal AA digestibility coefficients were determined for each food at each laboratory to evaluate interlaboratory variability. Three foods were evaluated twice in different cohorts of pigs at each laboratory (intralaboratory variation). RESULTS:There was no statistically significant effect (P > 0.05) of the laboratory on the true ileal AA digestibility coefficients for 8 of the foods. Differences in AA digestibility were found for wheat bread. The mean coefficient of variation (CV) between laboratories for digestibility of the indispensable AAs was 5.0% with an overall mean for all AAs of 5.5%. For intralaboratory variability, there were no statistically significant differences (P > 0.05) in AA digestibility for any food with mean CVs for each AA within each of the 3 laboratories for the indispensable AAs of 1.3%, 1.1%, and 0.9%. CONCLUSIONS:True ileal AA digestibility values determined in the growing pig for the same foods in different laboratories (interlaboratory variation) do not vary greatly. When a single food was evaluated a second time in the same laboratory, little variation among digestibility values was found.

Feeding whole prey to felids has shown to benefit their gastrointestinal health. Whether this effect is caused by the chemical or physical nature of whole prey is unknown. Fifteen domestic cats, as a model for strict carnivores, were either fed minced mice (MM) or whole mice (WM), to determine the effect of food structure on digestibility, mean urinary excretion time (MUET) of 15N, intestinal microbial activity and fermentation products. Faeces samples were collected after feeding all cats a commercially available extruded diet (EXT) for 10 d before feeding for 19 d the MM and WM diets with faeces and urine collected from day 11 to 15. Samples for microbiota composition and determination of MUET were obtained from day 16 to 19. The physical structure of the mice diet (minced or not) did not affect large intestinal fermentation as total SCFA and branched-chain fatty acid (BCFA), and most biogenic amine (BA) concentrations were not different (P > 0·10). When changing from EXT to the mice diets, the microbial community composition shifted from a carbolytic (Prevotellaceae) to proteolytic (Fusobacteriaceae) profile and led to a reduced faecal acetic to propionic acid ratio, SCFA, total BCFA (P < 0·001), NH3 (P = 0·04), total BA (P < 0·001) and para-cresol (P = 0·08). The results of this study indicate that food structure within a whole-prey diet is less important than the overall diet type, with major shifts in microbiome and decrease in potentially harmful fermentation products when diet changes from extruded to mice. This urges for careful consideration of the consequences of prey-based diets for gut health in cats.

OBJECTIVE:This study determined fermentation characteristics of commonly used feedstuffs, especially tropical roughages, for dairy cattle in Southeast Asia. This information is considered relevant in the context of the observed low milk fat content and milk production in Southeast Asia countries.METHODS:A total of 29 feedstuffs commonly used for dairy cattle in Vietnam and Thailand were chemically analysed and subjected to an in vitro gas production (GP) test. For 72 h, GP was continuously recorded with fully automated equipment and methane (CH4) was measured at 0, 3, 6, 9, 12, 24, 30, 36, 48, 60, and 72 h of incubation. A triphasic, nonlinear, regression procedure was applied to analyse GP profiles while a monophasic model was used to obtain kinetics related to CH4 production.RESULTS:King grass and VA06 showed a high asymptotic GP related to the soluble- and non-soluble fractions (i.e. A1 and A2, respectively) and had the highest acetate to propionate ratio in the incubation fluid. The proportion of CH4 produced (% of GP at 72 h) was found to be not different (p>0.05) between the various grasses. Among the selected preserved roughages (n = 6) and whole crops (n = 4), sorghum was found to produce the greatest amount of gas in combination with a relatively low CH4 production.CONCLUSION:Grasses belonging to the genus Pennisetum, and whole crop sorghum can be considered as suitable ingredients to formulate dairy rations to enhance milk fat content in Vietnam/Thailand.

Enhanced dietary Ca intake linearly increases intestinal Ca absorption in pigs, but not in broilers, suggesting potential differences in whole body Ca homeostasis. To determine the role of kidney in Ca homeostasis in these species, we varied in growing pigs in experiment (Exp) 1, the dietary Ca content 2·0 v. 9·6 g/kg and phytase 0 v. 500 FTU/kg, in broilers, in Exp 2 the dietary Ca/retainable P from 1·3 to 2·8 and phytase 0 v. 1000 FTU/kg, and in Exp 3 dietary Ca/P from 0·50 to 1·75. Increasing dietary Ca reduced renal mRNA expression of Ca-related transporters (TRPV5, TRPV6, CaBP-D28k and NCX1) and tight junctions (CLDN-12 and -16) in pigs, indicating Ca reabsorption was reduced to maintain Ca homeostasis. In broilers (Exp 2), high dietary Ca increased renal TRPV6, CaBP-D28k and CLDN-2 mRNA, indicating an increased capacity for Ca reabsorption. Moreover, the effect of dietary Ca was enhanced by inclusion of dietary phytase in pigs but reduced in broilers. Furthermore, increasing dietary Ca upregulated inorganic phosphate transporter 1 (PiT-1), while phytase downregulated xenotropic and polytropic retrovirus receptor 1 (XPR1) mRNA expression in pigs; in broilers, dietary Ca downregulated renal mRNA expression of Na-dependent phosphate transporter IIa (NaPi-IIa), PiT-1, PiT-2 and XPR1, while phytase downregulated NaPi-IIa but upregulated PiT-2 and XPR1 mRNA expression. In Exp 3, Ca/P effect on transporter mRNA expression was largely consistent with Exp 2. In conclusion of this study, together with previously measured data about Ca and P homeostasis, in pigs the kidneys play a more regulatory role in Ca homeostasis than in broilers where the intestine is more important for regulation.

The relationship between DM yield/cutting and the fermentable organic matter (FOM) content of tropical grasses was appropriately investigated to re-assess optimal grass maturity to feed dairy cattle. Nine different grass species belonging to the genera Brachiaria spp. (Mulato II, Ruzi), Panicum spp. (Guinea, Hamil, Mombasa, TD58), and Pennisetum spp. (King, Napier, VA06) were chemically analysed and subjected to an in vitro gas production (IVGP) test. For 72 h, gas production (GP) was continuously recorded with fully automated equipment. A triphasic, nonlinear, regression procedure was applied to analyse GP profiles. Across all the grasses, it was found that the neutral detergent fibre (NDF) contents increased with increasing maturity of the grass while the CP contents decreased with increasing NDF contents. In all nine grasses, digestible organic matter (dOM) was significantly affected by the week of cutting but IVGP was similar between the weeks of cutting in Ruzi, Hamil, Mombasa, and Napier grasses. Except for Guinea grass, the lowest dOM values were found when the grasses were cut after ≥5 weeks of regrowth. Harvesting grass one or two weeks earlier than the normal cutting time is a practically relevant intervention in increasing forage quality and productivity of dOM and fermentation potential.

As part of the transition to circular agriculture and to reduce food-feed competition for arable land, the inclusion of coproducts in livestock feed is expected to increase. Pellet manufacturing allows for improving the handling properties of livestock feed, but the effect of fibrous coproducts on the process is poorly understood. Inclusion of coproducts is considered to affect the physicochemical characteristics of a feed mash, and subsequently pellet manufacturing. To understand how coproducts can effectively be incorporated in pellet manufacturing, we investigated the effect of the inclusion of 300 g/kg of various fibrous coproducts, differing in fibrous composition, in feed mash containing 700 g/kg of basic mash, containing soybean meal, maize and soy oil, on mash physicochemical properties and pellet manufacturing. Treatment mashes were prepared in singleton, steam-conditioned and compacted using a ring-die pelletizer. Physical pellet quality, production capacity, and energy consumption of the pellet press were evaluated per treatment mash. Mash physicochemical properties were evaluated by determining hydration properties (i.e. water binding capacity and sorption analyses) and thermomechanical properties (i.e. phase transition and capillary rheometric analysis). Pellet durability varied among treatments (15.8–91.1 %), as did total energy costs of compaction (28.0–38.7 kWh/tonne). Principal component analysis indicated that higher levels of insoluble fibre in a feed mash associated with increased shear stress during capillary rheometric analysis. Combinedly these parameters reduced production capacity (R2 = 0.25; P = 0.046) and increased required energy consumption by the pellet press (R2 = 0.30; P = 0.03), but could only limitedly explain variation among treatments. In conclusion, the inclusion of coproducts with higher or lower levels of fibre did not consistently affect physical pellet quality. The overall low pellet durability (<90%) of all treatments, however, illustrates the challenge for the pellet manufacturing of diets containing fibrous coproducts. In addition the effects on energy costs of production should be considered during feed formulation.

This study evaluated the protein quality of small mammalian prey and its body organs by analyzing amino acid (AA) composition and digestibility of wild adult rats and their body organs (skin/fur, bone, muscle, intestine, liver, kidney, spleen, brain, heart, and lung) utilizing an in vitro digestion method. The average dry matter (DM) digestibility of whole rats was 89.9%. The digestibility of total AA (TAA), total indispensable AA (TIAA), and total dispensable AA (TDAA) in whole rats was 85.6, 87.0, and 87.6%, respectively. Differences in DM digestibility were observed among rat organs, ranging from 59.0% in bone to 99.8% in muscle (p < 0.001). Highly digestible organs generally exhibited AA digestibility exceeding 90%, except for cysteine (Cys) in the intestine and kidney (83.8 and 88.9%, respectively). The digestibility of AAs in skin/fur ranged from 19.7% for Cys to 81.0% for glycine (Gly). In bone, the digestibility spanned from 56.9% for Gly to 81.1% for tyrosine (Tyr). Additionally, examining the digestible indispensable AA score (DIAAS) gives us an idea of the protein quality of small mammalian prey and their body organs. Our results complement information on AA supply and digestion during prey ingestion by felids.