Initial evaluation of willow (Salix acmophylla) irrigated with treated wastewater as a fodder crop for dairy goats

Using attenuated-total-reflection Fourier-transformed spectroscopy to reveal molecular structural differences among willow (Salix spp.) foliage cultivars in relation to their potential as fodders

BACKGROUND

Willow trees represent a suitable species for the development of agroforestry systems, integrating bioenergy and animal feed production. However, there is a lack of information regarding the suitability of leaves and stems, considered a bioenergy by-product, as animal feed. The aim of this study was the employment of attenuated total reflectance Fourier transform infrared spectroscopy (550-4000 cm^-1 ) to investigate differences in the nutrient molecular structure profile of leaves and stems of selected willow cultivars to understand their utility for ruminant nutrition.

RESULTS

Univariate analysis of variance of leaves showed lower intensities of cellulosic compounds and higher of protein in comparison with stems, which suggests higher leaf dry matter and protein digestibility. Spectral analyses revealed differences in both plant parts between Salix cv. Terra Nova and Salix cv. Beagle, cv. Resolution, and cv. Olof. The higher α-helix to β-sheet ratio, which is related to a higher protein digestibility, was in correlation with the lower content of condensed tannins. Principal component and agglomerative hierarchical cluster analyses showed significant discrimination among willow cultivars in the cellulosic, structural carbohydrate, and amide regions, whereas differences were less evident for total carbohydrate and lipid-related regions.

CONCLUSION

The application of attenuated total reflectance Fourier transform infrared molecular spectroscopy is an effective tool to rapidly identify spectral features related to the nutritional composition of willow foliage and to discriminate between cultivars and parts of the plant. This information would be useful to optimize the use of willow fodders in agroforestry systems. © 2021 Society of Chemical Industry.

The Physiological Response of Different Brook Willow (Salix acmophylla Boiss.) Ecotypes to Salinity

Few phytoremediation studies have been conducted under semi-arid conditions where plants are subjected to drought and/or salinity stress. Although the genus Salix is frequently used in phytoremediation, information regarding its tolerance of drought and salinity is limited. In the present study, Salix acmophylla Boiss. cuttings from three sites (Adom, Darom and Mea She'arim) were tested for tolerance to salinity stress by growing them hydroponically under either control or increasing NaCl concentrations corresponding to electrical conductivities of 3 and 6 dS m^-1 in a 42-day greenhouse trial. Gas exchange parameters, chlorophyll fluorescence and concentration, and water-use efficiency were measured weekly and biomass was collected at the end of the trial. Root, leaf and stem productivity was significantly reduced in the Adom ecotype, suggesting that Darom and Mea She'arim are the more salt-tolerant of the three ecotypes. Net assimilation and stomatal conductance rates in salt-treated Adom were significantly reduced by the last week of the trial, coinciding with reduced intrinsic water use efficiency and chlorophyll a content and greater stomatal aperture. In contrast, early reductions in stomatal conductance and stomatal aperture in Darom and Mea She'arim stabilized, together with pigment concentrations, especially carotenoids. These results suggest that Darom and Mea She'arim are more tolerant to salt than Adom, and provide further phenotypic support to the recently published data demonstrating their genetic similarities and their usefulness in phytoremediation under saline conditions.

Rapid tannin profiling of tree fodders using untargeted mid-infrared spectroscopy and partial least squares regression

BACKGROUND

The presence of condensed tannins (CT) in tree fodders entails a series of productive, health and ecological benefits for ruminant nutrition. Current wet analytical methods employed for full CT characterisation are time and resource-consuming, thus limiting its applicability for silvopastoral systems. The development of quick, safe and robust analytical techniques to monitor CT's full profile is crucial to suitably understand CT variability and biological activity, which would help to develop efficient evidence-based decision-making to maximise CT-derived benefits. The present study investigates the suitability of Fourier-transformed mid-infrared spectroscopy (MIR: 4000-550 cm^-1) combined with multivariate analysis to determine CT concentration and structure (mean degree of polymerization-mDP, procyanidins:prodelphidins ratio-PC:PD and cis:trans ratio) in oak, field maple and goat willow foliage, using HCl:Butanol:Acetone:Iron (HBAI) and thiolysis-HPLC as reference methods.

RESULTS

The MIR spectra obtained were explored firstly using Principal Component Analysis, whereas multivariate calibration models were developed based on partial least-squares regression. MIR showed an excellent prediction capacity for the determination of PC:PD [coefficient of determination for prediction (R²P) = 0.96; ratio of prediction to deviation (RPD) = 5.26, range error ratio (RER) = 14.1] and cis:trans ratio (R²P = 0.95; RPD = 4.24; RER = 13.3); modest for CT quantification (HBAI: R²P = 0.92; RPD = 3.71; RER = 13.1; Thiolysis: R²P = 0.88; RPD = 2.80; RER = 11.5); and weak for mDP (R²P = 0.66; RPD = 1.86; RER = 7.16).

CONCLUSIONS

MIR combined with chemometrics allowed to characterize the full CT profile of tree foliage rapidly, which would help to assess better plant ecology variability and to improve the nutritional management of ruminant livestock.

The effect of willow fodder feeding on immune cell populations in the blood and milk of late-lactating dairy goats

In a previous study, we showed that access to willow fodder decreased somatic cell counts (SCC) in the milk of local Mamber goats grazing in brushland at the end of lactation. To test whether the consumption of willow affects the cells of the immune system, Alpine crossbred dairy goats grazing in the same environment were either offered free access to freshly cut willow fodder (W, n = 24) or not (C, n = 24) for 2 weeks. The willow fodder contained 7.5 g/kg DM of salicin. The other major secondary compounds were catechin, myricitrin, hyperin and chlorogenic acid (2.2, 2.6, 1.0 and 0.75 g/kg DM, respectively). Udder health status was determined before the experiment, and each of the two groups included five (W) or six (C) goats defined as infected, as established by microbial cfu in milk, and 19 (W) or 18 (C) non-infected goats. Goats ingested, on average, 600 g of DM from willow (25% of food intake), resulting in minor changes in dietary quality compared to the controls, as established by faecal near-IR spectrometry. Throughout the 2 weeks of experiment, differences between groups in dietary CP contents were minor and affected neither by infection nor by access to willow; the dietary percentage of neutral detergent fibre (NDF) decreased in C and increased in W; dietary acid detergent fibre (ADF) increased; and the dietary tannin contents decreased for both treatments. However, milking performance and milk quality attributes in both W and C goats were similar. Initial SCC and milk neutrophil (cluster of differentiation (CD)18⁺ and porcine granulocyte (PG)68) cell counts were higher in infected than in non-infected goats; counts decreased significantly in W but not in C uninfected goats. The percentage of CD8⁺ T-cells increased in all C goats, while in the W group, a significant increase was found only for infected goats. The consumption of willow mitigated an increase in CD8⁺ in blood and triggered an increase in CD8⁺ in milk, suggesting an immune-regulatory effect independent of udder status. To our knowledge, this is the first report of a direct nutraceutical effect of fodder ingestion on the immune status of goats.

Recent advances in the feeding and nutrition of dairy goats

There have been recent advances concerning research of the feeding and nutrition of dairy goats in a wide array of areas. Ruminally emitted methane and supplementary feedstuffs to a lesser extent make appreciable contributions to the carbon footprint of dairy goats, with the former affected by type of production system and associated dietary characteristics. Unique behavior of goats necessitates careful consideration of the nature of confinement facilities to achieve optimal production by animals differing in social hierarchy. Physiological conditions such as nutritional needs and perhaps health status may influence diet selection by goats in both grazing and confinement settings. Some research suggests that low concentrations of protein and fat in milk of high-yielding dairy goat breeds could involve the type and nature of dietary ingredients as influencing end products of ruminal fermentation. With the relationship between milk urea nitrogen concentration and efficiency of dietary protein utilization, through future research the measure may be a useful tool for diet formulation as in dairy cattle. Effects of dietary inclusion of sources of fats and oils vary considerably depending on their nature, as is also true for byproduct feedstuffs and conventional ones being substituted for. Supplementation of dairy goats with sources of polyunsaturated fatty acids can affect oxidative stress and various feedstuffs influence antioxidant status; however, research addressing the significance of such changes under practical production settings would be beneficial.