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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #374056
Research Project: Sustainable Intensification of Integrated Crop-Pasture-Livestock Systems in Northeastern Landscapes

Location: Pasture Systems & Watershed Management Research

Title: Brix as an indicator of energy value in alfalfa and orchardgrass pasture herbage

Author
item Billman, Eric
item Soder, Kathy
item HORST, JEFF - Agri Food - Canada
item BALK, KRISTI - Agri Food - Canada
item HAFLA, AIMEE - Agri Food - Canada

Submitted to: American Society of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2020
Publication Date: 11/5/2020
Citation: Billman, E.D., Soder, K.J., Horst, J., Balk, K., Hafla, A. 2020. Brix as an indicator of energy value in alfalfa and orchardgrass pasture herbage{abstract}. American Society of Animal Science Proceedings. p. 1.

Interpretive Summary: No Interpretive Summary is required for this Abstract Only. JLB.

Technical Abstract: This study correlated Brix values (measure of total dissolved solids via a refractometer) with wet-lab analyses (WLA) of sugar concentrations and nutritive value in fresh herbage of two common forage species, alfalfa (ALF; Medicago sativa) and orchardgrass (ORG; Dactylis glomerata). Four monthly samplings occurred from May-August, 2019. At each sampling, eight ALF and ORG samples were collected from established monocultures of each species. Solubles were extracted from fresh herbage using a hand-held garlic press. Triplicate Brix readings were recorded per sample using a digital Brix refractometer. Fresh herbage samples were flash-frozen in liquid N, freeze-dried, and analyzed via WLA for total and individual (glucose and fructose) sugar concentrations, as well as CP, NDF, and ADF (Agri-King, Inc., Fulton, IL). The TDN, RFV, and RFQ were calculated. Brix values were correlated with WLA results using the PROC CORR procedure in SAS, with significance established at P < 0.05 and trends at 0.05 < P < 0.10. Brix values were negatively correlated (P < 0.001) with WLA of total sugars (-0.65), glucose (-0.6), and fructose (-0.68) in ORG while no significant correlations (P > 0.10) were detected in ALF. Conversely, Brix values of both ORG and ALF were positively correlated (P < 0.01) with NDF (0.57 – 0.58) and hemicellulose (0.42 – 0.55), as well as with ADF in ALF (0.54). Brix was negatively correlated (P < 0.05) with CP in ALF (-0.41), but there was no correlation (P > 0.10) with ORG. No correlations (P > 0.10) were detected between Brix values and TDN, RFV, and RFQ. These results indicate that the Brix index does not directly translate to forage quality, particularly sugar concentrations, of ALF and ORG, and may inadvertently select herbage with increased fiber concentrations. Producers should consider more accurate methods, such as WLA, for assessing energy value of pasture herbage.