L.M. Rode

Effects of an exogenous enzyme preparation on microbial protein synthesis, enzyme activity and attachment to feed in the Rumen Simulation Technique (Rusitec).

The effects of an exogenous enzyme preparation, the application method and feed type on ruminal fermentation and microbial protein synthesis were investigated using the rumen simulation technique (Rusitec). Steam-rolled barley grain and chopped alfalfa hay were sprayed with water (control, C), an enzyme preparation with a predominant xylanase activity (EF), or autoclaved enzyme (AEF) 24 h prior to feeding, or the enzyme was supplied in the buffer infused into the Rusitec (EI). Microbial N incorporation was measured using (15NH4)2SO4 in the buffer. Spent feed bags were pummelled mechanically in buffer to segregate the feed particle-associated (FPA) and feed particle-bound (FPB) bacterial fractions. Enzymes applied to feed reduced neutral-detergent fibre content, and increased the concentration of reducing sugars in barley grain, but not alfalfa hay. Ruminal cellulolytic bacteria were more numerous with EF than with C. Disappearance of DM from barley grain was higher with EF than with C, but alfalfa was unaffected by EF. Treatment EF increased incorporation of 15N into FPA and FPB fractions at 24 and 48 h. In contrast, AEF reduced the 24 h values, relative to C; AEF and C were similar at 48 h. Infused enzyme (EI) did not affect 15N incorporation. Xylanase activity in effluent was increased by EF and EI, compared to C, but not by AEF. Xylanase activity in FPA was higher at 48 h than at 24 h with all treatments; it was higher with EF than C at 24 and 48 h, but was not altered by AEF or EI. Applying enzymes onto feeds before feeding was more effective than dosing directly into the artificial rumen for increasing ruminal fibrolytic activity.

Effects of fibrolytic enzymes in corn or barley diets on performance and carcass characteristics of feedlot cattle

A study was conducted to establish whether fibrolytic enzyme feed additives influence performance of feedlot cattle fed high grain diets, and to compare the effects of feeding diets of barley or corn on performance and carcass characteristics. Crossbred beef steers (408 kg) were offered high concentrate diets (95.1%, dry matter basis), consisting mainly of barley and barley silage or corn and corn silage. Concentrates were treated with either no enzyme or one of two enzyme mixtures. Calves were slaughtered after a 103- to 145-d feeding period at an average weight of 570 kg and 10.8 mm of backfat. Barley-fed calves grew faster (1.45 vs. 1.29 kg d−1), ate more dry matter (DM; 9.79 vs. 9.31 kg d−1), and converted DM to gain (6.85 vs. 7.35 kg DM kg−1gain) more efficiently compared with corn-fed calves (P < 0.001). Meat from barley-fed calves tended to be more highly marbled and was brighter in colour than meat from corn-fed calves, but diet had no effect on muscle score, rib eye area, or carcass leanness. Eff...

Mode of action of exogenous cell wall degrading enzymes for ruminants

Recent studies have shown that adding exogenous fibrolytic enzymes to ruminant diets can increase milk production of dairy cows and weight gain of growing beef cattle as a result of enhanced feed digestion. While much progress has been made in terms of advancing feed enzyme technology for ruminants, considerable research is still required to develop more effective enzyme products. The mode of action whereby exogenous enzymes improve digestion of plant cell wall is complex, and there is evidence for numerous potential modes of action suggesting they are interdependant. A mode of action that accounts for the most critical factors that explain the observed increases in feed digestion is presented. Adding exogenous enzymes to the diet increases the hydrolytic capacity of the rumen mainly due to increased bacterial attachment, stimulation of rumen microbial populations and synergistic effects with hydrolases of ruminal microorganisms. The net effect is increased enzymic activity within the rumen, which enhance...

Short Communication: Salivary Secretion During Meals in Lactating Dairy Cattle

Four multiparous Holstein cows in midlactation were used in a 4 x 4 Latin square to evaluate whether source of forage influenced salivary secretion during eating in lactating dairy cows. The forages were allocated separately from the pelleted concentrates. Cows were offered 1 of 4 forages each period: barley silage, alfalfa silage, long-stemmed alfalfa hay, or chopped barley straw. Saliva secretion was measured during the morning meal by collecting masticates through the rumen cannula at the cardia of each cow. Rate of salivation (213 g/min) was not affected by forage source. However, the forage sources differed in eating rate (g of DM/min), which led to differences in ensalivation of forages (g of saliva/g of DM and g of saliva/g of NDF). On the basis of DM, ensalivation (g of saliva/g of DM) was greatest for straw (7.23) and similar for barley silage, alfalfa silage, and alfalfa hay (4.15, 3.40, and 4.34 g/g of DM, respectively). Higher ensalivation of straw could be accounted for by its higher neutral detergent fiber (NDF) content; ensalivation of NDF (g of saliva/g of NDF) was actually greatest for long-stemmed alfalfa hay (12.4) and similar for the other chopped forages (8.9). Cows consumed concentrate about 3 to 12 times faster than the various forages (DM basis), and ensalivation of concentrate was much lower (1.12 g of saliva/g of DM) than for forages. Feed characteristics such as particle size, DM, and NDF content affect salivary output during eating by affecting the eating rate. Slower eating rate and greater time spent eating may help prevent ruminal acidosis by increasing the total daily salivary secretion in dairy cows.

USE OF FEED ENZYMES IN FEEDLOT FINISHING DIETS

An enzyme mixture with predominantly xylanase and cellulase activities was added to a high concentrate diet (92.2%, dry matter basis) and fed to growing heifers (370 kg) reared in a commercial feedlot. Enzyme supplementation had no effect on dry matter intake but increased (P < 0.01) average daily gain by 9% (1.40 to 1.53 kg d−1) and numerically improved feed-to-gain ratio by 10% (7.72 to 6.95 kg dry matter kg−1 gain). Feed enzyme technology can improve efficiency of commercial feedlot cattle production. Key words: Beef cattle, feedlot cattle, enzymes, barley

The influence of dietary cereal grain source and feed enzymes on the cooking properties and palatability attributes of beef

A total of 54 crossbred steers of similar genotype were randomly allocated to a 2 × 3 factorial arrangement of treatments including 2 diets (corn vs. barley) and 3 enzyme treatments (control, enzyme 1, and enzyme 2). Diets consisted of 95% concentrate and 5% silage for 105 to 147 d, following a 14-d step-up period from a 30% concentrate, 70% silage diet (dry matter basis). All animals were slaughtered using simulated commercial conditions after attaining a mean weight of 567.5 kg. The longissimus thoracis (LT) muscles were excised between the 9th and 12th ribs at 24 h postmortem. They were then vacuum packaged and aged for 14 d at 2 °C, before being frozen at −30 °C for subsequent evaluation by an experienced semi-trained laboratory panel and a highly trained flavor/texture profile panel. Source of dietary grain and dietary enzyme treatment generally failed to produce any important effects on the cooking properties or palatability attributes of beef. Beef from animals fed barley-based diets was slightly i...

Lignin impact on fiber degradation. IV. Enzymatic saccharification and in vitro digestibility of alfalfa and grasses following selective solvent delignification

The response in composition, in vitro dry matter digestibility (IVDDM), and enzymatic saccharification, of alfalfa and various grasses to selective solvent delignification (SSD), as well as the nutritive value of the residual biomass (co-product), was determined. The SSD pretreatment reduced lignin concentrations in grasses but not in alfalfa. Associated effects were increases in concentrations of neutral detergent fiber (NDF) due to losses of cell solubles (all forages) and changes in hemicellulose/cellulose ratio. SSD pretreatment increased IVDDM of the grasses by 11–25%, and this increase was highly correlated with the extent of delignification (r = 0.90). Extent of enzymatic fiber hydrolysis was up to 78%, with reducing sugar production of up to 371 mg/g DM. Differences in forage digestibility caused by stage of maturity were largely overcome by the SSD pretreatment. Fiber composition and IVDDM concentration of the co-products were indicative of low to medium nutritive value. SSD pretreatment seems uniquely capable of enhancing enzymatic saccharification and digestibility of mature, high-yielding grasses, such as giant wildrye.

Inhibition of ruminant feed enzyme polysaccharidase activities by extracts from silages

Extracts from 14 barley silages inhibited endo-1, 4-β-xylanase and α-amylase activities of a ruminant feed enzyme additive from Trichoderma longibrachiatum by 23 to 50% but had little effect on cellulase activity. The inhibitory factor(s) were <10 kDa in size and were stable to autoclaving. These observations may explain why feed enzymes are generally less effective when applied to silages than when applied to dry feeds. Key words: Silage, fibrolytic enzymes, Trichoderma, xylanase, inhibitors

Morphological study of the digestion of barley and maize grain by rumen microorganisms.

Abstract The cuticular surface of whole barley did not develop extensive bacterial colonization after 48 h of exposure to rumen bacterial populations in nylon-bag experiments. The inner surface of rolled barley was colonized via damage sites and eventually developed very large mixed adherent bacterial populations that effectively digested the cellulosic material from within. The endosperm was invaded by bacteria that formed an extensive mixed population in the inter-granular areas but the starch granules were more slowly colonized by Gram-negative rods. These organisms formed extensive adherent microcolonies on the surfaces of the starch granules, penetrated these granules using their proteolytic and amylolytic activities, and digested the inside of the starch granules. Comparative examinations of the digestion of ground maize showed that starch granules were similarly invaded by large Gram-negative cells resembling those of the genus Sarcina , which accumulated very large amounts of intracellular polysaccharide. These data suggest a sequential bacterial colonization of feed grains in the rumen, beginning on inner tissues exposed by physical damage and progressing towards the grain surface. Similarly, bacteria penetrate the surface of starch granules and digest their central contents. Therefore, both the feed grains and their component starch granules are digested from the inside outwards.

Effect of protein source on microbial protein synthesis and nutrient digestion in beef cattle fed barley grain-based diets

Four British cross heifers fitted with ruminal and duodenal cannulas were used in an experiment designed as a 4 × 4 Latin square. The basal diet was composed of 90% barley grain concentrate and 10% barley silage (DM basis) with either no protein supplementation (13.6% CP), or an additional 1.2% CP (% of DM) in the form of urea, canola meal (CM) or blood meal (BM). Ruminal ammonia N concentration was highest (P 0.05). Ruminal pH averaged 5.78 and was not affected by protein source (P = 0.97). Canola meal and BM tended (P 0.10). Ruminal OM and starch digestion were not affected by the dietary treatments (P > 0.10). In conclusion, barley grain-...