Protection of protein from ruminal degradation by alkali‐induced oxidation of chlorogenic acid in sunflower meal

Abstract

SummaryLactating ruminants require an adequate supply of absorbable amino acids for the synthesis of milk protein from two sources, that is crude protein (CP) synthesized microbially in the rumen and ruminally undegraded CP (RUP) from feed which can both be digested in the small intestine. Several chemical and physical methods have been identified as being effective in increasing the proportion of RUP of total CP of a feedstuff, yet there is a continuing need for developing and establishing methods which protect feed protein from ruminal degradation with acceptable expenditure of labour and other costs. The objective of this study was to identify and quantify effects of and interactions between chlorogenic acid and protein in solvent-extracted sunflower meal (SFM) as induced by alkali treatment. Response surface methodology was employed to investigate the influence of pH, reaction time and drying temperature on the resulting SFM and, subsequently, its protein value for ruminants estimated from laboratory values. For this purpose, alkali-treated SFM was subjected to a fractionation of feed CP according to the Cornell net carbohydrate and protein system as a basis for estimating RUP at different assumed ruminal passage rates (K p ). To estimate the intestinal digestibility of the treated SFM and its RUP, a three-step enzymatic in vitro procedure was applied. Alkaline treatment of SFM increased RUP values with factors ranging from approximately 3 (K p =.08/hr) to 12 (K p =.02/hr). Furthermore, the intestinal digestibility of the alkali-treated SFM was enhanced by approximately 10% compared to untreated SFM. Increasing pH and reaction time led to both increasing RUP values and intestinal digestibility. In conclusion, a targeted alkaline treatment of naturally occurring compounds in feedstuffs might be a promising approach to provide high-RUP feeds for ruminants which, at the same time, have improved intestinal digestibility values. K E Y W O R D Sinteractions, polyphenols, protected protein, protein degradation, rumen

Methods assessment of self-tanning of rapeseed and sunflower meal fractions enriched in proteins and phenolic compounds using in vitro measurement of protein rumen degradability

“…4) and isovalerate. The hierarchy between fractions, however, was similar to that observed with rapeseed meal, CO pretreatment being associated with the lowest ammonia production, in agreement with the results of Bongartz et al (2018).…”

“…ATP from fermentations was therefore used to provide the energy needed for microbial growth and not to maintain a neutral intracellular pH (Strobel and Russell, 1986). Our observations based on a biological test implementing rumen microbiota activity extend to rapeseed meal the conclusions of Bongartz et al (2018) who measured by an enzymatic method a decrease in proteolysis in a CO treated sunflower meal.…”

“…However, a second way of cold and alkaline tanning could exist. Recently, (Bongartz et al, 2018) have shown that the alkaline treatment of sunflower meal induces the formation of chlorogenic acid quinones which react with the proteins of the meal. This phenomenon leads to the reduction of the simulated degradation of proteins by rumen microorganisms.…”

The PHENOLEO project or how to separate and add-value to phenolic compounds present in rapeseed and sunflower meals

“…Phenolic compounds present in rapeseed meal and sunflower meal samples have been studied for their ability to interact with proteins that might lead to the reduction of their simulated degradation by rumen microorganisms (Wischer et al, 2013;Bongartz et al, 2018). Thus, we aim to quantify the impact of treatmentshot or cold and at basic pHon the rumen degradability of proteins in rapeseed and sunflower positive fraction of the electrodes (PFe of U-RSM-0.1 and U-SFM-0.5) previously obtained after electrostatic-sorting in Section 2.1.2 (Broudiscou et al, 2020).…”

“…Quinones and radicals can also react with the amino acids of the meal proteins, causing browning and changes in their organoleptic characteristics and techno-functional properties (Ozdal et al, 2013). Nevertheless, these o-quinones/proteins association also leads to the reduction of simulated degradation of proteins by rumen microorganisms meaning that phenolic compounds could possibly be used as tanning agents in order to replace formaldehyde (Hernández-Jabalera et al, 2015;Bongartz et al, 2018). Indeed, the lower rumen degradability of proteins is primarily tanned by formaldehyde, which reacts primarily with some amino acids to form methylene bonds that cause crosslinking of proteins (Barry, 1976).…”