Electrophoretic examination of alfalfa silage proteins

• Published in: Journal of dairy science Vol. 74; no. 1; pp. 146 - 154
• Main Authors: Grum, D.E. (The Ohio State University, Wooster), Shockey, W.L, Weiss, W.P
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Dairy Sci Assoc 01.01.1991; American Dairy Science Association
• Subjects: ACIDE FORMIQUE; ACIDO FORMICO; ADDITIF AUX ALIMENTS DES ANIMAUX; ADITIVO DE PIENSOS; ALFALFA; AMMONIAC; AMONIACO; AZOTE NON PROTEIQUE; Biological and medical sciences; ENSILADO; ENSILAGE (PRODUIT); ENSILAGE (TRAITEMENT); ENSILAJE; Feed and pet food industries; FERMENTACION; FERMENTATION; Food industries; FORMALDEHIDOS; FORMALDEHYDE; Fundamental and applied biological sciences. Psychology; LUZERNE; NITROGENO NO PROTEICO; PROTEINAS; PROTEINE; PROTEOLISIS; PROTEOLYSE; SOLUBILIDAD; SOLUBILITE; TEMPS; TIEMPO; Plant protein; Electrophoresis; Silage; Proteolysis; Dairy industry; Feed
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(91)78155-1

Effects of silage additives on proteolysis of ensiled alfalfa were studied using PAGE. First-cutting alfalfa was wilted (40% DM), chopped, and ensiled into 60 X 10-cm polyvinyl chloride silos. Treatments were control or treatment with glucose (50 g/kg DM), ammonium hydroxide (25 g/kg DM), or formic acid-formaldehyde (2:1 mixture of 90% HCOOH:37% HCOH applied at 1.83% of the DM). Samples were collected on d 0, 1, 2, 4, 7, 21, and 50 of fermentation. Samples were analyzed for N, NPN, ammonia N, pH, lactic acid, acetic acid, and soluble sugar. Also, buffer-soluble protein was characterized using PAGE. During fermentation of control silage, pH and concentrations of soluble sugar declined, and concentrations of lactic and acetic acidsand NPN increase, indicating a normal fermentation. Similar shifts in concentrations of compounds occurred in treated silage but to a different extent. Proteins from alfalfa herbage and silage were characterized into molecular weight ranges based on relative mobility, and their disappearance with time of fermentation was estimated. Buffer-extractable proteins decreased rapidly with time of fermentation and essentially disappeared by d 7. Proteolysis was inhibited by formic acid-formaldehyde and ammonium hydroxide treatments but not by glucose. Formic acid-formaldehyde decreased the amount of extractable proteins by decreasing their solubility in the extraction buffer. Apparent degradation and extractability of proteins by buffer were affected by silage treatments; however, because buffer-extractable proteins represented only 36 to 40% of total plant proteins, results must be interpreted cautiously until better extraction procedures are developed