Effect of feeding cellulase enzyme on productive responses of pregnant and lactating ewes and goats

Exogenous fibrolytic enzymes promoted energy and nitrogen utilization and decreased CH4 emission per unit dry matter intake of tan sheep grazed a typical steppe by enhancing nutrient digestibility on China loess plateau

Exogenous fibrolytic enzyme (EFE) products in ruminant nutrition may be an important alternative to meet the increased demands for animal products in the future with reduced environmental impacts. This study aimed to evaluate the dose-response of EFE supplementation on the nutrient digestibility, nitrogen and energy utilization, and methane (CH4) emissions of Tan sheep grazed in summer and winter. A total of 20 Tan wether sheep with an initial body weight of 23.17 ± 0.24 kg were used in a randomized complete block design and categorized into two groups. Animals fed orally with 1 g of EFE (10,000 U/g) mixed with 30 mL of water using a drencher constituted the EFE group. For experimental accuracy, the control (CON) group was orally administered with 30 mL of normal saline daily before grazing. The following results were obtained: EFE in the diet increased dry matter intake (DMI) (P < 0.05), average daily gain (ADG) (P < 0.05), and digestibility (P < 0.05) compared with CON in summer and winter. DMI increased but ADG and digestibility decreased in winter compared with those in summer. Sheep fed with the EFE diet increased the concentrations of rumen ammonia nitrogen (P < 0.05) and total volatile fatty acids (P > 0.05), but reduced pH (P > 0.05), compared with CON in summer and winter. EFE increased nitrogen (N) intake, digestible N, retained N, and retained N/digestible N (P < 0.05) but reduced fecal N/N intake, urinary N/N intake, and excretion N/N intake in summer and winter (P < 0.05), compared with CON. Retained N/N intake was reduced and excretion N/N intake increased in winter relative to those in summer. In winter, gross energy (GE), manure E/GE, CH4 emissions, CH4/DMI, and CH4/GE increased but digestion energy and metabolic energy decreased compared with those in summer. Sheep fed with the EFE diet had a greater GE intake than those fed with the CON diet (P < 0.05) but had lesser CH4/DMI and CH4E/GE (P < 0.05) than those fed with the CON diet in both summer and winter. In conclusion, EFE supplementation increased DMI, apparent digestibility, and N deposition rate. These effects were beneficial for animal production. The CH4 emission per unit DMI of grazing Tan sheep was lesser and conducive for augmenting the environmental benefits.

The Cytosolic Oligosaccharide-Degrading Proteome of Butyrivibrio Proteoclasticus

The growth and productivity of ruminants depends on a complex microbial community found in their fore-stomach (rumen), which is able to breakdown plant polysaccharides and ferment the released sugars. Butyrivibrio proteoclasticus B316T is a Gram-positive polysaccharide-degrading, butyrate-producing bacterium that is present at high numbers in the rumen of animals consuming pasture or grass silage based diets. B316T is one of a small number of rumen fibrolytic microbes capable of efficiently degrading and utilizing xylan, as well as being capable of utilizing arabinose, xylose, pectin and starch. We have therefore carried out a proteomic analysis of B316T to identify intracellular enzymes that are implicated in the metabolism of internalized xylan. Three hundred and ninety four proteins were identified including enzymes that have potential to metabolize assimilated products of extracellular xylan digestion. Identified enzymes included arabinosidases, esterases, an endoxylanase, and β-xylosidase. The presence of intracellular debranching enzymes indicated that some hemicellulosic side-chains may not be removed until oligosaccharides liberated by extracellular digestion have been assimilated by the cells. The results support a model of extracellular digestion of hemicellulose to oligosaccharides that are then transported to the cytoplasm for further digestion by intracellular enzymes.

Use of 'natural' products as alternatives to antibiotic feed additives in ruminant production

The banning in 2006 of the use of antibiotics as animal growth promoters in the European Union has increased demand from producers for alternative feed additives that can be used to improve animal production. This review gives an overview of the most common non-antibiotic feed additives already being used or that could potentially be used in ruminant nutrition. Probiotics, dicarboxylic acids, enzymes and plant-derived products including saponins, tannins and essential oils are presented. The known modes of action and effects of these additives on feed digestion and more especially on rumen fermentations are described. Their utility and limitations in field conditions for modern ruminant production systems and their compliance with the current legislation are also discussed.

Extracellular polysaccharide-degrading proteome of Butyrivibrio proteoclasticus

Plant polysaccharide-degrading rumen microbes are fundamental to the health and productivity of ruminant animals. Butyrivibrio proteoclasticus B316(T) is a gram-positive, butyrate-producing anaerobic bacterium with a key role in hemicellulose degradation in the rumen. Gel-based proteomics was used to examine the growth-phase-dependent abundance patterns of secreted proteins recovered from cells grown in vitro with xylan or xylose provided as the sole supplementary carbon source. Five polysaccharidases and two carbohydrate-binding proteins (CBPs) were among 30 identified secreted proteins. The endo-1,4-β-xylanase Xyn10B was 17.5-fold more abundant in the culture medium of xylan-grown cells, which suggests it plays an important role in hemicellulose degradation. The secretion of three nonxylanolytic enzymes and two CBPs implies they augment hemicellulose degradation by hydrolysis or disruption of associated structural polysaccharides. Sixteen ATP-binding cassette (ABC) transporter substrate-binding proteins were identified, several of which had altered relative abundance levels between growth conditions, which suggests they are important for oligosaccharide uptake. This study demonstrates that B. proteoclasticus modulates the secretion of hemicellulose-degrading enzymes and ATP-dependent sugar uptake systems in response to growth substrate and supports the notion that this organism makes an important contribution to polysaccharide degradation in the rumen.