An Illustrative Analysis of Atypical Gas Production Profiles Obtained from In Vitro Digestibility Studies Using Fecal Inoculum

Enhancing physicochemical, rheological properties, and in vitro rumen fermentation of starch with Melastoma candidum D. Don fruit extract

The utilization of polyphenol-modified starch in ruminants has not undergone extensive exploration. This study aimed to investigate the impact of the complex formed between starch and Melastoma candidum D. Don fruit extract on physicochemical properties, phenol release kinetics in various buffers simulating the gastrointestinal tract, methane production, and post-rumen digestibility. The interaction between starch and M. candidum D. Don fruit extract significantly (p < 0.001) increased resistant starch and particle size diameter. The maximum phenolic release from complex between starch and M. candidum D. Don fruit extract, due to gastrointestinal tract-simulated buffers, ranged from 22.96 to 34.60 mg/100 mg tannic acid equivalent. However, rumen and abomasum-simulated buffers released more phenolic content, whereas the intestine-simulated buffer showed higher antioxidant activity (ferric ion-reducing antioxidant power). Furthermore, complex between starch and M. candidum D. Don fruit extract significantly decreased dry matter rumen digestibility (p < 0.001) and maximum methane gas production (p < 0.001).

In vitro digestion and fermentation of Japanese macaque (Macaca fuscata) food: The influence of food type and particle size

Chewing is critical for herbivores to obtain nutrients. Measuring digesta particle size as the outcome of chewing can improve our understanding of the relationship between food and digestion. Previous studies of feeds of domestic animals have shown that smaller digesta particle size leads to more efficient digestion. Increased digesta particle size-either due to animal factors (e.g., a senile dentition) or to feed factors (e.g., fracture resistance) could be a sign of an animal experiencing compromised nutritional intake. However, for some primates that are dietary generalists, digesta particle size has been shown to increase when consuming preferred foods, which raises doubts about the role of chewing in digesting such foods. This uncertainty makes it difficult to understand the connection between diet, chewing, and digestion through digesta particle size in dietary generalists. In this study, using five typical food items from the Japanese macaque (Macaca fuscata) diet, we conducted in vitro digestibility and fermentation assays to explore the effects of particle size on enzymatic and microbial digestion. For the fermentation assays, we used feces from captive Japanese macaques as inoculum. Among the five food items, we found that particle size has a stronger influence on the digestibility of seeds and mature leaves compared to young leaves and pulp. The influence of particle size on the fermentation rate was stronger in pulp and seeds compared to that in leaves. The differences in physical structure, texture, digestion barriers, and soluble components may play important roles in such differences. These results support the hypothesis that reducing food particle size is less important for consuming fruits than for consuming leaves. The limited effects of particle size on digesting fruits suggest that the two fruits examined in this study are cost-effective concerning food processing and chewing.