Effects of Neltuma spp. Pod Inclusion on In Vitro Ruminal Fermentation Kinetics, Ruminal Metabolic Activity Indicators, and Digestive Health in Sheep

During the dry season in semi-arid regions, pastures become scarce and low in nutritional quality. These conditions compromise the digestive physiology and ruminal health of sheep. Consequently, consuming forages high in fibre and deficient in nitrogen leads to reduced digestive efficiency. Evaluating unconventional local resources, such as the pods of Neltuma spp., is essential for determining their ability to optimise fermentation kinetics without disrupting the ruminal ecosystem. The objective of this study was to evaluate the effects of replacing commercial feed with increasing levels of Neltuma spp. pods (20%, 40%, and 60%) collected from three geographic regions of Zacatecas, Mexico, on in vitro ruminal fermentation kinetics, microbial activity parameters, and digestive health indicators, measured in sheep ruminal fluid. Samples of Neltuma spp. pods were collected from three regions of the state of Zacatecas, and mixtures were prepared using commercial feed and ground Neltuma spp. pods in ratios of 80:20, 60:40, and 40:60, which were subjected to bromatological analysis; a ruminal fluid inoculum obtained from Dorper sheep adapted to a diet based on commercial feed was used for in vitro fermentation. Gas pressure, ammoniacal nitrogen concentration, and pH were monitored every 6 h during a 48 h incubation period. Principal component analysis, analysis of variance, and Tukey’s tests for comparing means were conducted to evaluate the effects of inclusion level and region of origin. The first two principal components explained 99.08% of the total variability, demonstrating a correlation between the content of fibrous fractions and the proportion of non-fibrous carbohydrates. In vitro ruminal fermentation showed an upward trend across all treatments over time; mixtures with a moderate pod inclusion level of 20% achieved the highest gas production volumes. Ammoniacal nitrogen profiles showed a progressive increase across all treatments. The fermentation pH decreased gradually as the carbohydrate degradation process progressed. It is concluded that the inclusion of 20% and 40% Neltuma spp. pods, particularly those from the central region, represents a viable nutritional strategy for improving energy and protein intake in sheep during the dry season.