Wouter Hendrikus Hendriks

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.

Housefly larvae ( Musca domestica L.) can convert livestock manure into protein-rich biomass, addressing challenges in waste management and feed sustainability. This study investigated the combined effects of carbohydrate supplementation, larval density and harvest time on the growth and survival of housefly larvae reared on chicken excreta and on excreta bioconversion. A 3 × 4 × 2 factorial design comprised three carbohydrate treatments (unsupplemented, glucose-supplemented and starch-supplemented chicken excreta), four egg densities (8, 12, 16, 20 eggs/g substrate) and two harvest times (58 and 120 h). Carbohydrate supplementation increased larval biomass production and improved dry matter and nitrogen bioconversion relative to unsupplemented excreta, with responses generally increasing with egg density but plateauing at higher densities in starch-supplemented excreta, particularly at the later harvest. Larval survival rates at 58 h were similar among treatments, but by 120 h survival rates were markedly lower at low egg densities in both supplemented substrates. Increasing egg density largely eliminated these reductions, demonstrating that the effects of carbohydrate supplementation on survival were density dependent. Compared with unsupplemented and glucose-supplemented excreta, starch supplementation consistently resulted in lower residue pH. Factor analysis revealed that the dominant source of multivariate variation shifted from substrate at the 58 h harvest to egg density at the 120 h harvest. These findings demonstrate that the benefits of carbohydrate supplementation depend not only on substrate composition but also on larval density and harvest time, indicating the need to optimise these factors jointly in housefly manure bioconversion systems.

The consumption of forages high in slow-degradable carbohydrates by dairy cattle leads to greater ruminal acetate production, which benefits milk fat content. Although tropical grasses are typically rich in fibrous materials, the milk fat content of dairy cows in Southeast Asia is low. Here, we investigate the effects of the species and harvest time of three common tropical grasses (Guinea, King, and Mulato II) harvested at three instances (early, normal, late) on in sacco degradation kinetics and in vitro gas production (IVGP) characteristics. Grass samples were subjected to (1) chemical analysis, (2) a fully automated in vitro gas recording system using rumen fluid to measure fermentation characteristics over 72 h, and (3) in sacco degradation using the nylon bag technique, employing seven incubation times up to 336 h. Forage quality decreased with maturity, as reflected in changes to digestibility and fiber content. Overall, early harvested grasses yielded the highest total gas production (311 ± 12.5 mL/g OM) followed by normal (300 ± 45.7 mL/g OM) and late (273 ± 19.5 mL/g OM) harvested grasses. The in vitro fermentable fraction (A1 + A2) was the highest for early harvested grasses, with the A2 parameter, relevant for milk fat content, being the highest for Guinea (81.6% A2/(A1 + A2)) and the lowest for King grass (71.0% A2/(A1 + A2)). Consequently, early harvested Guinea had the longest incubation times (10.5 h) and lowest fermentation rates (Rmax2 = 12.8 mL/g OM/h). Regression analysis showed relationships between NDF content and degradability. Harvesting tropical grass earlier than customarily practiced enhanced forage quality and ruminal degradability. Of the three grasses studied, each at three levels of maturity, early harvested Guinea grass was the most promising candidate for improving milk fat content in Southeast Asian dairy cows. This grass showed a high fermentable OM content, with a large proportion of slow-degradable carbohydrates.

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 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.

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.

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.

The relationship between DM yield/cutting and fermentable organic matter (FOM) content of tropical grasses was appropriately investigated to re-access 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 analyzed 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 fiber (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 weeks of cutting in Ruzi, Hamil, Mombasa, and Napier grass. 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 normal cutting time is a practically relevant intervention in in-creasing forage quality and productivity of dOM and fermentation potential.

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) of¹⁵N, 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.