Ensiling willow (Salix acmophylla) fodder modifies the contents of plant specialized metabolites, but not nutritional attributes
. ANIMAL FEED SCIENCE AND TECHNOLOGY 2021
Willow (Salix spp.) is grown for energy biomass in temperate regions and is also a promising source of feed for ruminants. Willow fodder contains high concentrations of beneficial plant specialized metabolites (PSMs). We investigated the efficacy of ensiling willow fodder in 1.5 L jars without (control-C) or with silage additives (lactobacilli-LAB, molasses-M, or the combination MLAB), and the effects on nutritional attributes of ensiling willow in 60 L drums with LAB. We also assessed the effect of ensiling willow fodder on PSMs by liquid chromatography / time-offlight / mass spectrometry (LC-TOF-MS). Exact or tentative compound identification was established, depending on availability of appropriate standards. In jars, LAB-supplemented silages reached lowest pH (4.2). M-supplemented silages had lower aNDF and aADF contents. IVDMD was higher in M than in C, and the contents of crude protein (CP) were not affected by silage treatments. Ensiling in drums did not affect the major nutritional components of willow fodder. Even though phenylalanine, arginine, tyrosine, histidine, and methionine, but not tryptophan, were increased 3.8-7.9-fold by ensiling, the finding is of low importance, as free amino acids are totally degraded in the rumen. In contrast, the main PSM, i.e., the salicinoid salicin was 74 % deglycosylated, concomitantly with a ten-fold increase in salicylic acid concentration and with the appearance of acetyl-salicylic acid; likewise, the flavonoids hyperin and rutin were 66 % deglycosylated, consequent with a 48-fold increase in quercetin concentration. As the bioavailability of the quercetin aglycone is inferior to that of its glycosylated counterparts, ensiling might affect the nutraceutical value of willow fodder. Likewise, catechin, gallocatechin and epicatechin were totally metabolized by ensiling. Overall, ensiling willow fodder (with LAB) does not affect the nutritional attributes of willow fodder but it greatly alters its PSM concentrations and, possibly impairs its nutraceutical value. However, as anti-oxidative activity is supposed to increase, following de-glycosylation, further research is needed to evaluate a possible trade-off on nutraceutical value between the glycosylated and aglycone forms of phenolics contained in willow fodder.
A NIRS-Aided Methodology to Elucidate the Nutrition of the Endangered Mountain Gazelle (Gazella gazella) Using Samples of Rumen Contents from Roadkills
. REMOTE SENSING 2021
The populations of the endangered mountain gazelle (Gazella gazella), which inhabit large parts of Israel, across various ecosystems and climatic conditions, shrunk drastically over the last decades. To date, data on gazelle nutrition, how these relate with individual characteristics and respond to seasonal and environmental changes, have not been available. We analyzed 110 samples from gazelle rumen contents collected throughout the country from occasional fatalities, mainly roadkills, and tested the feasibility of using them for near-infrared spectrometry (NIRS) calibrations. Although NIR calibrations for crude protein, in vitro dry matter digestibility, and ash were reasonable, we found that using calibrations based on local forage and feed plant species performed better, and used these to estimate several nutritional constituents in gazelle rumens, using NIRS. We tested how constituents relate to the sex, age-class, and weight of the individual gazelle, and to season and ecosystem type, and found that season plays a major role in gazelle nutrition. Winter is the most propitious season, when crude protein, ash and digestibility are highest, and acid detergent fiber (ADF), neutral detergent fiber (NDF), and the carbon to nitrogen (C:N) ratio are lowest. Autumn, being the harshest season, mirrors winter conditions, and summer and spring show intermediate levels. Yet the relative changes between seasons were mild: about 30%, for crude protein, digestibility, and ash, and 14-22% for ADF, NDF, and C:N ratio. Ecosystem type affected several constituents, and nutrition was slightly better in Mediterranean than in dry ecosystems. Gazelle sex, weight, and age-class had minor effects on nutrition. Overall, it seems that the adaptation of gazelles to their environment is germane to keeping relatively steady nutrition throughout the year. Our results, which do not show a dramatic decline in the quality of gazelle nutrition during any season or among the climatic regions that were studied, suggest that nutrition is not a major driver of the survival of gazelles in the populations surveyed.