Silage additives to reduce protein degradation during ensiling and evaluation of in vitro ruminal nitrogen degradability

Abstract

Despite the high degradability of their proteins, grass and legume silages represent an important option to reach more sustainable livestock systems. To improve the nitrogen use efficiency of these crops, this study assessed the potential of several additives (chestnut tannins, oak tannins, zeolite, erythritol by‐product solution and wood molasses) to reduce proteolysis in the silo and in vitro nitrogen degradability. Ryegrass (Lolium multiflorum) and red clover (Trifolium pratense) were ensiled in varying proportions in laboratory‐scale silos made of vacuum‐packed plastic bags. Dry‐matter content, chemical composition, pH, ammonia and volatile fatty acids content were analysed after 34 days of ensiling. Ruminal nitrogen degradability was assessed in vitro (Aufrère & Cartailler, ). We observed that the proportion of ammonia in silage was reduced by the addition of oak tannin (−12%) and zeolite (−16%). The addition of zeolite lowered in vitro organic matter digestibility. Rapidly degradable nitrogen (1‐hr degradability) was reduced in vitro by both tannins (−6.8% for chestnut and −6.6% for oak) and zeolite (−5.8%), but total degradable nitrogen (24‐hr degradability) was only reduced by oak (−6.5%) and chestnut tannins (−7.3%). It suggests that tannins protected proteins from plant and bacterial enzymes by forming a complex that better resists silage fermentations and in vitro protease action. The reduction effects on proteolysis in the silo and on in vitro ruminal nitrogen degradability are limited individually but could be cumulative. Erythritol by‐product solution and wood molasses had no effect on silo or in vitro proteolysis.

Effect of additives on fermentation characteristics, nutrient values and <i>in vitro</i> fermentation profile of <i>Neolamarckia cadamba</i> leaf silage

“…In the present study, all the silages had relative low protein solubility in the borate-phosphate buffer, where UC-S and CA-S had increased (P <0.05) soluble crude protein, inferring that uncompacted silage suffered more severe proteolysis, given its high NPN concentration, and the addition of citrate caused more protein acidolysis. The low protein solubility may be because of the high tannin content (condensed tannin>7%), because tannin extracts are able to bind with proteins to form complexes and prevent protein hydrolysis in silage and in the rumen (Piluzza et al, 2014;Herremans et al, 2019). It was reported that naturally occurring condensed tannins contributed to the reduced proteolysis of alfalfa during conservation (Grabber & Coblentz, 2009).…”

Calidad fermentativa y producción de metano en ensilados de rastrojo de maíz adicionados con nopal fermentado y sin fermentar

“…La concentración de nitrógeno amoniacal en los ensilados se incrementó con la inclusión de nopal y nopal fermentado (P<0.05, tabla 3). Este incremento registrado en los ensilados del t2 y t3 pudo haber sido ocasionado por un aumento en los microorganismos que degradan proteína (Berumen et al, 2015;Ruangyote y Metha, 2018), o también el empleo de rastrojo de maíz reduce la cantidad de carbohidratos solubles y por lo tanto aumenta la degradación de proteínas (Herremans et al, 2019). Sin embargo, para clasificar un ensilado como de buena calidad, la concentración de nitrógeno amoniacal máxima debe ser de 7-20 % del nitrógeno total (Sánchez y García, 2017); por lo cual los ensilados experimentales obtuvieron valores que se encuentran dentro de este rango y por lo tanto indican que se llevó a cabo un adecuado proceso de fermentación.…”

Opportunities Offered by Plant Bioactive Compounds to Improve Silage Quality, Animal Health and Product Quality for Sustainable Ruminant Production: A Review

“…In a study comparing the effects of tannin levels in sorghum silages supplemented or not with tannin-inactivating polyethylene glycol (PEG), silages without PEG had higher protein levels and lower NH 3 concentrations than silages with PEG [26]. Tannins can also be successfully supplemented in silage via byproducts (e.g., green tea waste, [27] and plant extracts containing hydrolysable tannins from chestnut and oak [28,29] or condensed tannins from quebracho [30].…”

“…Other PBC including erythritol byproduct solution and lignosulphonates from wood molasses were studied as silage additives to reduce in-silo proteolysis but were shown to be less efficient compared to tannin solutions [29]. In contrast, spraying essential oils (eugenol, thymol, cinnamaldehyde and carvacrol) before ensiling ryegrass was shown to reduce protein degradation, but usually had to be sprayed at a concentration of 2 g/kg fresh forage to observe inhibition of amino acid deamination [34].…”