Synergistic effects of mixing cocksfoot and sainfoin on in vitro rumen fermentation. Role of condensed tannins

Low drying temperature has negligible impact but defatting increases in vitro rumen digestibility of insect meals, with minor changes on fatty acid biohydrogenation

BACKGROUND

Insect meals have been identified as innovative and sustainable feedstuffs that could be used in ruminant nutrition. However, current research on the effects that their processing may have on rumen digestibility and fatty acid (FA) biohydrogenation is scant. This trial aims to investigate the effects (i) of drying temperature of full-fat Hermetia illucens (HI) and Tenebrio molitor (TM) meals, and (ii) of residual ether extract (EE) content of defatted HI and TM meals, on their fermentation characteristics and FA of rumen digesta after 24-h in vitro rumen incubation.

METHODS

The tested full-fat meals included four HI and four TM meals obtained applying drying temperatures ranging from 30 °C to 70 °C, while the tested defatted meals consisted of five HI and two TM meals containing a residual EE content ranging from 4.7 to 19.7 g EE/100 g dry matter (DM). The applied statistical models (GLM ANOVA) tested the effects of insect species, drying temperature (full-fat meals) or EE content (defatted meals), and their interaction.

RESULTS

Drying temperature had minor effects on in vitro ruminal digestibility and FA profile of rumen digesta. Irrespective of insect species, increasing the drying temperature led to a reduction of in vitro degradation of proteins from insect meals, as outlined by the significant decrease in ammonia production (-0.009 mmol/g DM and -0.126 g/100 g total N for each additional 1 °C). Irrespective of insect species, defatting increased total gas, volatile fatty acids (VFA) and CH4 productions, and the proportions of total saturated and branched-chain FA in rumen digesta (+0.038 mmol/g DM, +0.063 mmol/g DM, +12.9 µmol/g DM, +0.18 g/100 g FA, and +0.19 g/100 g FA for each reduced 1 g EE/100 g DM, respectively), and reduced the proportion of total PUFA (-0.12 g/100 g FA).

CONCLUSIONS

The applied drying temperatures of full-fat insect meals are too low to exert impactful effects on rumen digestibility and FA biohydrogenation. Fat lowered fermentation activity, probably because of an inhibitory effect on rumen microbiota. The increased ruminal digestibility of defatted insect meals suggests that they can be more suitable to be used in ruminant nutrition than full-fat ones.

Evaluation of the Associative Effects of Rice Straw with Timothy Hay and Corn Grain Using an In Vitro Ruminal Gas Production Technique

Simple Summary

Rice straw is a widely used forage source for ruminants in most Asian countries; thus, it is important to accurately estimate its nutritional value. Rice straw is typically fed to the animals along with other ingredients, and the associative effects of the combined ingredients may alter the nutritional value of rice straw. We found associative effects on the ruminal fermentability (gas production kinetics and rumen parameters), especially when rice straw was co-fermented with timothy hay and corn grain. We conclude that the nutritional value of rice straw increases when used with timothy hay and corn grain, due to the associative effects among feeds, which should be considered in diet formulations.

Abstract

The objective of this study was to evaluate the associative effects of rice straw with timothy hay and corn grain. Using an automated gas production system, in vitro ruminal fermentation was studied for six substrates: 100% rice straw, 100% timothy hay, 100% corn grain, 50% rice straw and 50% timothy hay, 50% rice straw and 50% corn grain, and 50% rice straw, 25% timothy hay, and 25% corn grain. Incubation was performed in three batches with different rumen fluids to assess the in vitro ruminal gas production kinetics and rumen parameters (pH, NH₃-N, volatile fatty acid (VFA), and true dry matter digestibility (TDMD)). The associated effects were tested by comparing the observed values of the composited feeds and the weighted means of individual feeds. There was a significant increase in NH₃-N when rice straw was fermented with timothy hay, corn grain, or both (p < 0.05). TDMD increased when corn grain was co-fermented, and the total gas and VFA production increased when all three feeds were co-fermented. We conclude that the feed value of rice straw increases when fed to animals along with timothy hay and corn grain.

Nutritive value of forage biomass from sainfoin mixtures

Forage quality characteristics of field-grown mixtures of sainfoin with cocksfoot (50:50%), sainfoin with tall fescue (50:50%), and the same with the addition of subterranean clover in their composition (33:33:33%) were measured. Forage biomass from the mixtures of sainfoin with cocksfoot had generally higher forage quality than mixtures with tall fescue. It had higher crude protein content (11.52% of dry matter (with 1.07% units), significantly higher digestibility (61.74%) (with 6.51% units), higher neutral detergent fiber content (53.42%) (with 3.22% units), higher nutritive value (Unité Fourragère Viande – Unité Fourragère Lait, 0.690–0.583) and higher protein feeding value (Total Digestible Protein – Protein digestible dans l’intestine in dependence of nitrogen – Protein digestible dans l’intestine in dependence of energy), 72–70–79 g/kg of dry matter. Forage biomass showed more balanced basic chemical composition after the addition of subterranean clover, i.e.: higher crude protein content (with 0.30% units) and lower crude fiber content (with 0.14% units) for mixtures with cocksfoot; higher digestibility (with 0.29% units) for mixtures with cocksfoot; lower neutral detergent fiber content (with 0.45% units) for mixtures with cocksfoot and with 3.15% units for mixtures with tall fescue, higher energy feeding value (Unité Fourragère Viande – Unité Fourragère Lait) (with 0.007–0.012 for mixtures with cocksfoot and with 0.009–0.014 for mixtures with tall fescue), higher protein feeding value for both mixtures with cocksfoot and tall fescue. Forage biomass from mixtures of sainfoin with cocksfoot and Trifolium subterraneum ssp. brachycalicinum had the highest crude protein (11.89% of dry matter), the lowest crude fiber content (27.07% of dry matter) and the highest digestibility (62.81% of dry matter).

Methane Production of Fresh Sainfoin, with or without PEG, and Fresh Alfalfa at Different Stages of Maturity is Similar but the Fermentation End Products Vary

Alfalfa and sainfoin are high-quality forages with different condensed tannins (CT) content, which can be affected by the stage of maturity. To study the effects of CT on fermentation parameters, three substrates (alfalfa, sainfoin, and sainfoin+PEG) at three stages of maturity were in vitro incubated for 72 h. Sainfoin had greater total polyphenol and CT contents than alfalfa. As maturity advanced, CT contents in sainfoin decreased (p < 0.05), except for the protein-bound CT fraction (p > 0.05). The total gas and methane production was affected neither by the substrate nor by the stage of maturity (p > 0.05). Overall, sainfoin and sainfoin+PEG had greater in vitro organic matter degradability (IVOMD) than alfalfa (p < 0.05). Alfalfa and sainfoin+PEG presented higher ammonia content than sainfoin (p < 0.001). Total volatile fatty acid (VFA) production was only affected by the stage of maturity (p < 0.05), and the individual VFA proportions were affected by the substrate and the stage of maturity (p < 0.001). In conclusion, alfalfa and sainfoin only differed in the IVOMD and the fermentation end products. Moreover, CT reduced ammonia production and the ratio methane: VFA, but the IVOMD was reduced only in the vegetative stage.

Potential of legume-based grassland-livestock systems in Europe: a review

European grassland-based livestock production systems face the challenge of producing more meat and milk to meet increasing world demands and to achieve this using fewer resources. Legumes offer great potential for achieving these objectives. They have numerous features that can act together at different stages in the soil-plant-animal-atmosphere system, and these are most effective in mixed swards with a legume proportion of 30-50%. The resulting benefits include reduced dependence on fossil energy and industrial N-fertilizer, lower quantities of harmful emissions to the environment (greenhouse gases and nitrate), lower production costs, higher productivity and increased protein self-sufficiency. Some legume species offer opportunities for improving animal health with less medication, due to the presence of bioactive secondary metabolites. In addition, legumes may offer an adaptation option to rising atmospheric CO₂ concentrations and climate change. Legumes generate these benefits at the level of the managed land-area unit and also at the level of the final product unit. However, legumes suffer from some limitations, and suggestions are made for future research to exploit more fully the opportunities that legumes can offer. In conclusion, the development of legume-based grassland-livestock systems undoubtedly constitutes one of the pillars for more sustainable and competitive ruminant production systems, and it can be expected that forage legumes will become more important in the future.