Compound enzyme preparation supplementation improves the production performance of goats by regulating rumen microbiota

Enzyme preparation is one of the widely used additives in ruminant production. However, a suitable method of adding compound enzyme preparation (CEP) to the feeds is still lacking. This study investigated the effect of adding CEP on the diet of goats. Twenty 4-month-old Boer goats were randomly assigned to four groups. The dietary treatments contained different CEPs (Saccharomyces cerevisiae cells, cellulase, xylanase, β-glucanase amylase, and protease) at the concentrations of 0, 0.25, 0.50, and 0.75 g/kg of feed provided for a period of 56 days. Adding CEP in goat feed significantly increased average daily gain (ADG) during the entire test period. The oxidative indices, hormones, and immune cells did not differ significantly among the different groups. CEP significantly increased the content of total volatile fatty acids measured at the end of the experiment on day 56 of the final normal feeding phase. 16S rDNA sequencing revealed that CEP increased the abundance of Ruminococcaceae in the rumen and g__norank_f__Eubacterium_coprostanoligenes_group, Oscillibacter g__unclassified_f__Ruminococcaceae, and g__unclassified_o__Oscillospirales in fecal matter collected on day 56 of the final normal feeding phase. However, CEP decreased the abundance of unclassified_f__Lachnospiraceae, norank_f__UCG-010, Butyrivibrio, and Saccharofermentans in the rumen. The abundance of Ruminococcaceae in the rumen and propionic acid was positively correlated with ADG. Function prediction showed that carbon fixation, carbohydrate digestion and absorption pathways were significantly enriched in rumen microbiota in the treatment group. The findings indicated that supplementation with 0.5 g CEP/kg of feed for 56 days significantly improves the production performance of goats without adverse health effects. KEY POINTS: • Feeding with compound enzyme preparation for 56 days significantly improved the productive performance but did not affect the antioxidative capacity and immunity of goats. • Supplementing compound enzyme preparation in diet could increase the relative abundance of Ruminococcus to increase the levels of short-chain fatty acids produced. • The most appropriate supplemental amount of compound enzyme preparation per kilogram of the diet was 0.5 g.

Fermentation Patterns, Methane Production and Microbial Population under In Vitro Conditions from Two Unconventional Feed Resources Incorporated in Ruminant Diets

In this study, four experimental treatments were evaluated: (T1) alfalfa hay + concentrate, (50:50%, DM); (T2) alfalfa hay + Leucaena leucocephala + concentrate, (30:20:50%, DM); (T3) alfalfa hay + prickly pear + concentrate, (30:20:50%, DM); and (T4) alfalfa hay + Leucaena leucocephala + prickly pear + concentrate, (30:10:10:50%, DM). NH3-N concentrations in T2 and T4 decreased when replaced with alfalfa hay in 20 and 10%, respectively. Treatments did not affect the concentration of total volatile fatty acids (TVFA) between T3 and T4 (p > 0.05), while the concentrations among T1 and T2 were different (p < 0.05). T2 showed a reduction of 25.5% in the methane production when compared to T1 (p < 0.05). The lowest concentrations of protozoa were observed in T2 and T4, which contained Leucaena leucocephala (T2) and Leucaena leucocephala + prickly pear (T4) (p < 0.05). The highest concentration of total methanogens was recorded in T1 and was different in T2, T3, and T4 (p < 0.05). Leucaena leucocephala, at an inclusion percentage of 20%, decreased the methane when compared to T1, whereas prickly pear increased methane production in relation to T1.

Utilization of exogenous fibrolytic enzymes in fiber fermentation, degradation, and digestions and characteristics of whole legume faba bean and its plant silage

This article aims to review recent progress and update on utilization of exogenous fibrolytic enzymes in fiber fermentation, degradation, and digestions and nutritive and anti-nutritional characteristics of whole legume faba bean and its silage. The study focused on strategies to improve the utilization and bioavailability of fiber through pre-treating exogenous fibrolytic enzymes. The review includes features of nutrition and anti-nutritional factors and environment impact, forage fiber fermentation, degradation and digestion, legume bean in various diets, use of exogenous enzyme and factor affecting enzyme action in fiber digestion as well as exogenous enzyme response. This review also provides very recent research on effects of fibrolytic enzyme on rumen degradation characteristics of dry matter and fiber of whole plant faba bean silage and effect of exogenous fibrolytic enzyme derived from trichoderma reesei on lactational performance, feeding behavior, rumen fermentation and nutrient digestibility in dairy cows fed whole plant faba bean silage-based diet. This study provides an insight on nutritive and anti-nutritive characteristics of whole legume bean and its plant silage and utilization of exogenous fibrolytic enzymes in fiber fermentation, degradation, and digestions.

Effects of a xylanase-rich enzyme on intake, milk production, and digestibility of dairy cows fed a diet containing a high proportion of bermudagrass silage

We previously reported that milk production in dairy cows was increased by adding a specific xylanase-rich exogenous fibrolytic enzyme (XYL) to a total mixed ration (TMR) containing 10% bermudagrass silage (BMD). Two follow-up experiments were conducted to examine whether adding XYL would increase the performance of dairy cows consuming a TMR containing a higher (20%) proportion of BMD (Experiment 1) and to evaluate the effects of XYL on in vitro fermentation and degradability of the corn silage, BMD, and TMR (Experiment 2). In Experiment 1, 40 lactating Holstein cows in early lactation (16 multiparous and 24 primiparous; 21 ± 3 d in milk; 589 ± 73 kg of body weight) were blocked by milk yield and parity and randomly assigned to the Control and XYL treatments. The TMR contained 20% BMD, 25% corn silage, 8% wet brewer's grain, and 47% concentrate mixture in the dry matter (DM). Cows were fed the XYL-treated or untreated experimental TMR twice per day for 10 wk after a 9-d covariate period. In Experiment 2, ruminal fluid was collected from 3 cannulated lactating Holstein cows fed a diet containing 20% bermudagrass haylage, 25% corn silage and 55% concentrate. In Experiment 1, compared with Control, application of XYL did not affect DM intake (24.0 vs. 23.7 kg/d), milk yield (35.1 vs. 36.2 kg/d), fat-corrected milk yield (36.1 vs. 36.9 kg/d), or yields of milk fat (1.29 vs. 1.31 kg/d) or protein (1.07 vs. 1.08 kg/d). However, intake of neutral detergent fiber (4.67 vs. 4.41 kg/d) tended to increase with XYL; consequently, milk protein concentration was increased by XYL (3.02 vs. 2.95%). Feed efficiency tended to be lower in cows fed XYL (1.57 vs. 1.52 kg of fat-corrected milk/kg of DM intake) compared with Control. In Experiment 2, XYL tended to increase the rate of gas production in the TMR, the molar proportion of propionate for corn silage, and that of valerate for the TMR. In addition, XYL increased in vitro DM, neutral detergent fiber, and acid detergent fiber degradability of BMD and corn silage. Application of XYL to a diet with a relatively high proportion of BMD tended to increase digestible neutral detergent fiber intake, increased milk protein concentration, and in vitro degradability of DM, neutral detergent fiber, and acid detergent fiber. However, XYL did not affect milk production and tended to decrease feed efficiency in early lactation cows.

Effect of Xylanase and Phytase Supplementation on Goat's Performance in Early Lactation

BACKGROUND AND OBJECTIVES

Supplementing diets of dairy animals with phytase and xylanase can enhance phosphorus availability and fiber degradation in the rumen and positively affect animal's health and productivity. In vitro and in vivo trials have been conducted to define the optimal addition level of xylanase and phytase to lactating Baldi goat's rations and investigate effects of these enzymes on animal's nutrients digestibility, blood chemistry, milk production and milk composition.

MATERIALS AND METHODS

In vitro batch culture technique was used to evaluate the effect of phytase and xylanase supplementation at different levels (0, 1, 2 and 3 g kg-1 DM) on rumen fermentation characteristics. Eighteen early lactating Baldi goats were randomly assigned into three groups and fed 4% dry matter according to their body weight. The first group was fed control ration (35% yellow corn, 20% corn stalks, 20% berseem hay, 12.5% soybean meal and 12.5% wheat bran), the second group fed control ration+Penizyme at 2 g kg-1 DM (R1), while the third group fed control ration+Phtase-Plus® at 1 g kg-1 DM (R2).

RESULTS

Xylanase and phytase supplementation increased the in vitro DM and OM degradability and ruminal NH3-N and total volatile fatty acids (TVFA) concentrations, with no effect on total gas production (TGP) volume. All nutrients digestibility (except CP), blood serum glucose concentration, milk production and milk components yields were increased for enzymes supplemented goats than control.

CONCLUSION

Inclusion of xylanase and phytase in lactating goat's rations improved their productive performance with no deleterious effects on their health.

Effects of dietary exogenous fibrolytic enzymes on ruminal fermentation characteristics of beef steers fed high- and low-quality growing diets1

The effects of dietary pretreatment with fibrolytic enzyme-based cocktail were evaluated in 2 studies: (1) in vitro true digestibility; and (2) intake, digestibility, feeding behavior, and ruminal fermentation of beef steers fed growing diets. For the in vitro assessment, the ruminal inoculum was collected from 2 steers (BW = 543 ± 45 kg; 4-h after feeding; growing diets) and enzymes included or not (Trichoderma reesei fermentation extract; 0.75 µL/g of substrate DM). Within in vitro batches (n = 4), 12 substrates were incubated and in vitro true nutrient digestibility was evaluated. For study 2, 5 ruminally cannulated beef steers (BW = 520 ± 30 kg) were used in a 5 × 4 unbalanced Latin square using a 2 × 2 factorial arrangement of treatments: (a) diet quality (high = HQ; and low = LQ) and (b) enzyme inclusion (0 or 0.75 mL/kg of diet DM). Steers were fed ad libitum during four 21-d periods consisting of 14-d of adaptation and 7-d of collections. An enzyme × substrate was observed (P < 0.01), in which DM, OM, and NDF disappearance of sorghum grain increased with enzymes addition. Addition of enzymes increased (P < 0.01) ADF digestibility for all substrates. No diet quality × enzyme (P ≥ 0.18) was observed for intake variables in study 2. Enzyme-fed steers increased (P ≤ 0.05) intake of DM, digestible DM, NDF, and ADF compared with steers not fed fibrolytic enzymes. Addition of enzyme did not affect (P ≥ 0.28) apparent total tract digestibility of beef steers. Steers fed HQ diets consumed more (P ≤ 0.04) DM, digestible DM and OM, and less (P ≤ 0.03) total and digestible fiber than steers fed LQ diets. Ruminal pH average decreased (P = 0.01) for steers fed HQ or enzyme-fed diets compared with other treatments. A tendency (P = 0.06) toward improved total VFA was observed on enzyme-fed steers with HQ diets, but not for LQ diets. The molar proportion of ruminal propionate increased (P = 0.01) when steers were fed enzyme. Steers fed HQ diets had greater (P < 0.01) propionate and valerate molar proportions, lower (P < 0.01) acetate and acetate:propionate ratio than steers fed LQ diets. In vitro methane and total gas production were not affected (P ≥ 0.50) by dietary treatments. Fibrolytic enzymes positively affected digestion of multiple roughage sources commonly fed to cattle and might have additional benefit when used on unprocessed sorghum grain. Fibrolytic enzymes in beef cattle growing diets stimulated intake and generated positive impacts on ruminal fermentation.

Symposium review: Technologies for improving fiber utilization

The forage lignocellulosic complex is one of the greatest limitations to utilization of the nutrients and energy in fiber. Consequently, several technologies have been developed to increase forage fiber utilization by dairy cows. Physical or mechanical processing techniques reduce forage particle size and gut fill and thereby increase intake. Such techniques increase the surface area for microbial colonization and may increase fiber utilization. Genetic technologies such as brown midrib mutants (BMR) with less lignin have been among the most repeatable and practical strategies to increase fiber utilization. Newer BMR corn hybrids are better yielding than the early hybrids and recent brachytic dwarf BMR sorghum hybrids avoid lodging problems of early hybrids. Several alkalis have been effective at increasing fiber digestibility. Among these, ammoniation has the added benefit of increasing the nitrogen concentration of the forage. However, few of these have been widely adopted due to the cost and the caustic nature of the chemicals. Urea treatment is more benign but requires sufficient urease and moisture for efficacy. Ammonia-fiber expansion technology uses high temperature, moisture, and pressure to degrade lignocellulose to a greater extent than ammoniation alone, but it occurs in reactors and is therefore not currently usable on farms. Biological technologies for increasing fiber utilization such as application of exogenous fibrolytic enzymes, live yeasts, and yeast culture have had equivocal effects on forage fiber digestion in individual studies, but recent meta-analyses indicate that their overall effects are positive. Nonhydrolytic expansin-like proteins act in synergy with fibrolytic enzymes to increase fiber digestion beyond that achieved by the enzyme alone due to their ability to expand cellulose microfibrils allowing greater enzyme penetration of the cell wall matrix. White-rot fungi are perhaps the biological agents with the greatest potential for lignocellulose deconstruction, but they require aerobic conditions and several strains degrade easily digestible carbohydrates. Less ruminant nutrition research has been conducted on brown rot fungi that deconstruct lignocellulose by generating highly destructive hydroxyl radicals via the Fenton reaction. More research is needed to increase the repeatability, efficacy, cost effectiveness, and on-farm applicability of technologies for increasing fiber utilization.

Effect of harvest method and ammoniation of baled corn residue on intake and digestibility in lambs

To determine the effect of harvest method and ammoniation on both in vivo and in vitro digestibility of corn residue, six corn residue treatments consisting of three different harvest methods either with or without anhydrous ammonia chemical treatment (5.5% of dry matter [DM]) were evaluated. The harvest methods included conventional rake-and-bale (CONV) and New Holland Cornrower with eight rows (8ROW) or two rows (2ROW) of corn stalks chopped into the windrow containing the tailings (leaf, husk, and upper stem) from eight rows of harvested corn (ammoniated bales of each harvest method resulted in treatments COVAM, 8RAM, and 2RAM). Nine crossbred wether lambs (49.2 ± 0.5 kg BW) were fed 64.2% corn residue, 29.8% wet corn gluten feed, 3.3% smooth-bromegrass hay, and 2.8% mineral mix (DM basis) in a 9 × 6 Latin rectangle metabolism study with a 3 × 2 factorial treatment to measure total tract disappearance. Six 21-d periods consisted of 14-d adaptation and 7-d total fecal collection, and lambs were fed ad libitum (110% of the previous day's DM intake [DMI]) during days 1 to 12 and reduced to 95% of ad libitum intake for days 13 to 21. There was a harvest method by ammoniation interaction (P < 0.01) for ad libitum DMI (days 7 to 11). Ammoniation increased (P < 0.01) intake across all harvest methods, where 2RAM DMI was 4.1%, COVAM was 3.6%, and 8RAM was 3.1%, which were all different (P < 0.01) from each other, but all untreated residues were consumed at 2.6% of BW (P ≥ 0.92) regardless of harvest method. There were no interactions (P > 0.34) between harvest method and ammoniation for any total tract or in vitro digestibility estimate. Harvest method affected (P < 0.04) DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility, where 2ROW was greater than both CONV and 8ROW, which did not differ. The organic matter (OM) digestibility (P = 0.12) and digestible energy (DE; P = 0.30) followed the same numerical trend. Both in vitro DM digestibility (IVDMD) and in vitro OM digestibility (IVOMD) of the residue were affected (P < 0.01) by harvest method, with 2ROW being greater (P < 0.01) than both CONV and 8ROW. For IVDMD, 8ROW was not (P = 0.77) different from CONV, but 8ROW IVOMD was lower (P = 0.03) than CONV. Ammoniation improved (P < 0.01) DM, OM, NDF, and ADF digestibility of all harvest methods, resulting in a 26% increase (P < 0.01) in DE due to ammoniation. Similar digestibility improvements were observed in vitro with ammoniation improving IVDMD and IVOMD by 23% and 20%, respectively. Both selective harvest methods and ammoniation can improve the feeding value of baled corn residue.

Influence of adding fibrolytic enzymes on the ruminal fermentation of date palm by-products

This study was conducted in order to assess the influence of four doses (0, 0.5, 1, and 2 mg (g dry matter) - 1 of commercial fibrolytic enzymes (MAXFIBER-I ® , SHAUMANN GmbH, Wahlstedt, Germany) on in vitro fermentation of date palm (Phoenix dactylifera) by-products: date kernels, wasted dates, floral stems, and palm fronds. Rumen contents were obtained from two non-lactating Holstein cows. Enzyme supplementation to by-products was carried out 12 h prior to incubation. Compared to the control, the enzymatic supplementation quadratically increased the extent but not the gas production rate of date kernel fermentation. Indeed, the potential gas production increased notably by 14.8 % with the lowest enzymes dose following recorded gas production after 48, 72, and 96 h of incubation. The estimated organic-matter digestibility, metabolisable energy, and total volatile fatty acids in the incubation fluid tended to be increased with the lowest dose by 7.8 %, 8.4 %, and 13.9 % respectively. For the wasted dates, this feed additive tended to linearly increase the gas production rate of fermentation with the highest dose. On the other hand, this supplementation had no effect on the ruminal fermentation of the floral stems and palm fronds. The exogenous fibrolytic enzymes were more effective on fibrous but not on lignified date palm by-products.

Selection for residual feed intake affects appetite and body composition rather than energetic efficiency

Residual feed intake (RFI) is the difference between an animal’s actual feed intake and that which would be expected based on production. This experiment was to test the hypothesis that part of the variation in RFI may be due to differences in energetic efficiency through changes in heat production, these being in part due to differences in protein metabolism. Following three generations of divergent selection for RFI, eight High and eight Low-RFI heifers were fed at both 105% and 180% of predicted maintenance feed requirements. Between-RFI line and feeding-level differences were assessed for energy intake, protein metabolism, heat production, body composition, energy and nitrogen balance and digestibility. The RFI lines did not differ in protein metabolism or heat production. The High-RFI heifers deposited 51% and 56% more subcutaneous fat at the P8 rump and 12/13th rib sites, respectively, with no difference in eye muscle area gain or average daily weight gain. The greater fat deposition of High-RFI heifers was due to a larger ad libitum feed consumption compared with the Low-RFI heifers. Energy and nitrogen balance did not differ between the RFI lines. The energy transactions indicated no difference in the efficiency of energy use on 105% maintenance, although when fed 180% of maintenance the differences in feed intake suggest variation in appetite as the mechanism contributing to RFI. All of the extra energy consumed by High-RFI heifers above maintenance and deposition of protein was associated with additional energy retained as fat. This study suggests that selection for RFI may not lead to improved efficiency of energy use.

Effects of exogenous enzymes and application method on nutrient intake, digestibility and growth performance of Pelibuey lambs

Pelibuey sheep is the main breed in the tropical and subtropical regions of Mexico, and high demand of sheep meat has favored the finishing of lambs in feedlots with diets containing high levels of grains. The objective of this study was to evaluate the effects of exogenous enzymes (EE) and application method on nutrient intake and digestibility and performance of growing Pelibuey lambs. Treatments were based on comparison of two different methods of adding an enzyme product (sprayed on the total mixed ration or applied orally to the lambs) versus control treatment (no added enzyme). Twenty-one Pelibuey lambs, weighing 15.7 kg (SD = 1.8 kg) initial body weight, were individually housed in shaded pens and assigned randomly to one of the three enzyme treatments. At the end of study (lasting for 45 days), three lambs from each treatment were randomly selected and adapted to a pants and harness designed for fecal collection to measure nutrient digestibilities. Total body gain and average daily gain were affected (P < 0.05) by supplemental EE. The application method of EE had significant (P < 0.05) effect on FCE and FCR, but no effects were observed on nutrient intake. Supplemental EE did improve (P < 0.05) the digestibilities of dry matter, organic matter, neutral and acid detergent fiber, but no differences were observed in crude protein digestibility. The application method of EE had significant (P < 0.05) effect on the digestibility of acid detergent fiber. Supplemental EE can improve body weight gain and nutrient digestibilities without affecting nutrient intake in Pelibuey lambs, but the results of feed conversion efficiency and acid detergent fiber digestibility depend on the application method used of the EE.

Fiber degradability, chemical composition and conservation characteristics of alfalfa haylage ensiled with exogenous fibrolytic enzymes and a ferulic acid esterase-producing inoculant

Lynch, J. P., Prema, D., Van Hamme, J. D., Church, J. S. and Beauchemin, K. A. 2014. Fiber degradability, chemical composition and conservation characteristics of alfalfa haylage ensiled with exogenous fibrolytic enzymes and a ferulic acid esterase-producing inoculant. Can. J. Anim. Sci. 94: 697–704. This study investigated the effects of two fibrolytic enzyme products, applied at baling alone or in combination with a ferulic acid esterase-producing bacterial additive, on the ensilage dynamics, chemical composition and digestibility of alfalfa haylage. Five replicate wrapped bales were produced with one of five treatments, including an untreated control, and one of two fibrolytic enzyme products (EN1 and EN2) applied either alone or in combination with a ferulic-acid producing bacterial additive (FAEI). No effect of treatment was observed on the neutral detergent fiber (NDF) (P=0.889) or acid detergent fiber (ADF) (P=0.065) concentrations of haylage after ensilage, but haylage produced using fibrolytic enzyme products underwent greater (P<0.018) increases in temperature following exposure to aerobic conditions. Haylages produced with fibrolytic enzyme products had a greater (P<0.001) in vitro NDF degradability (NDFD) than untreated haylage. The use of fibrolytic enzymes applied to alfalfa haylage at ensiling increased the NDFD, despite minimal effects on the chemical composition of the herbage. However, the greater aerobic deterioration of fibrolytic enzyme-treated bales indicates higher dry matter losses during aerobic exposure. The use of FAEI with fibrolytic enzymes did not further enhance the effects of fibrolytic-enzyme treatments.

Effect of microbial inoculants on the quality and aerobic stability of bermudagrass round-bale haylage

The objective of this study was to compare the efficacy of using 4 commercially available microbial inoculants to improve the fermentation and aerobic stability of bermudagrass haylage. We hypothesized that the microbial inoculants would increase the fermentation and aerobic stability of the haylages. Bermudagrass (4-wk regrowth) was harvested and treated with (1) deionized water (control); (2) Buchneri 500 (B500; Lallemand Animal Nutrition, Milwaukee, WI) containing 1×10(5) of Pediococcus pentosaceus and 4×10(5) of Lactobacillus buchneri 40788; (3) Biotal Plus II (BPII; Lallemand Animal Nutrition) containing 1.2×10(5) of P. pentosaceus and Propionibacteria freudenreichii; (4) Silage Inoculant II (SI; AgriKing Inc., Fulton, IL) containing 1×10(5) of Lactobacillus plantarum and P. pentosaceus; and (5) Silo King (SK; AgriKing Inc.), containing 1×10(5) of L. plantarum, Enterococcus faecium, and P. pentosaceus, respectively. Forty round bales (8 per treatment; 441±26kg; 1.2×1.2 m diameter) were made and each was wrapped with 7 layers of plastic. Twenty bales were stored for 112 d and the remaining 20 were stored for 30 d and sampled by coring after intermediary storage periods of 0, 3, 7, and 30 d. The pH of control and inoculated haylages sampled on d 3 did not differ. However, B500 and BPII had lower pH (5.77±0.04 vs. 6.16±0.04; 5.06±0.13 vs. 5.52±0.13) than other treatments by d 7 and 30, respectively. At final bale opening on d 112, all treatments had lower pH than the control haylage (4.77±0.07 vs. 5.37±0.07). The B500, BPII, and SI haylages had greater lactic acid and lactic-to-acetic acid ratios than SK and control haylages. No differences were detected in neutral detergent fiber digestibility, dry matter losses, dry matter, lactic and acetic acid concentrations, and yeast and coliform counts. The SK haylage had lower clostridia counts compared with the control (1.19±0.23 vs. 1.99±0.23 cfu/g). Treatments B500, BPII, SI, and SK tended to reduce mold counts and they improved aerobic stability by 236, 197, 188, and 95%, respectively, compared with the control (276±22 vs. 99±22h).

Considerations on the use of exogenous fibrolytic enzymes to improve forage utilization

Digestion of cell wall fractions of forage in the rumen is incomplete due to the complex links which limit their degradation. It is therefore necessary to find options to optimize the use of forages in ruminant production systems. One alternative is to use exogenous enzymes. Exogenous fibrolytic enzymes are of fungal or bacterial origin and increase nutrient availability from the cell wall, which consists of three fractions in different proportions depending on the species of forage: digestible, potentially digestible, and indigestible. The response to addition of exogenous enzymes varies with the type of forage; many researchers infer that there are enzyme-forage interactions but fail to explain the biological mechanism. We hypothesize that the response is related to the proportion of the potentially digestible fraction. The exogenous enzyme activity depends on several factors but if the general conditions for enzyme action are available, the potentially digestible fraction may determine the magnitude of the response. Results of experiments with exogenous fibrolytic enzymes in domestic ruminants are inconsistent. This, coupled with their high cost, has made their use unattractive to farmers. Development of cheaper products exploring other microorganisms with fibrolytic activity, such as Fomes fomentarius or Cellulomonas flavigena, is required.

Ruminant Nutrition Symposium: Improving cell wall digestion and animal performance with fibrolytic enzymes

This paper aimed to summarize published responses to treatment of cattle diets with exogenous fibrolytic enzymes (EFE), to discuss reasons for variable EFE efficacy in animal trials, to recommend strategies for improving enzyme testing and EFE efficacy in ruminant diets, and to identify proteomic differences between effective and ineffective EFE. A meta-analysis of 20 dairy cow studies with 30 experiments revealed that only a few increased lactational performance and the response was inconsistent. This variability is attributable to several enzyme, feed, animal, and management factors that were discussed in this paper. The variability reflects our limited understanding of the synergistic and sequential interactions between exogenous glycosyl hydrolases, autochthonous ruminal microbes, and endogenous fibrolytic enzymes that are necessary to optimize ruminal fiber digestion. An added complication is that many of the standard methods of assaying EFE activities may over- or underestimate their potential effects because they are based on pure substrate saccharification and do not simulate ruminal conditions. Our recent evaluation of 18 commercial EFE showed that 78 and 83% of them exhibited optimal endoglucanase and xylanase activities, respectively, at 50 °C, and 77 and 61% had optimal activities at pH 4 to 5, respectively, indicating that most would likely act suboptimally in the rumen. Of the many fibrolytic activities that act synergistically to degrade forage fiber, the few usually assayed, typically endoglucanase and xylanase, cannot hydrolyze the recalcitrant phenolic acid-lignin linkages that are the main constraints to ruminal fiber degradation. These factors highlight the futility of random addition of EFE to diets. This paper discusses reasons for the variable animal responses to dietary addition of fibrolytic enzymes, advances explanations for the inconsistency, suggests a strategy to improve enzyme efficacy in ruminant diets, and describes differences among the proteomes of effective and ineffective EFE.

Board-invited review: Opportunities and challenges in using exogenous enzymes to improve ruminant production

The ability of ruminants to convert plant biomass unsuitable for human consumption into meat and milk is of great societal and agricultural importance. However, the efficiency of this process is largely dependent on the digestibility of plant cell walls. Supplementing ruminant diets with exogenous enzymes has the potential to improve plant cell wall digestibility and thus the efficiency of feed utilization. Understanding the complexity of the rumen microbial ecosystem and the nature of its interactions with plant cell walls is the key to using exogenous enzymes to improve feed utilization in ruminants. The variability currently observed in production responses can be attributed to the array of enzyme formulations available, their variable activities, the level of supplementation, mode of delivery, and the diet to which they are applied as well as the productivity level of the host. Although progress on enzyme technologies for ruminants has been made, considerable research is still required if successful formulations are to be developed. Advances in DNA and RNA sequencing and bioinformatic analysis have provided novel insight into the structure and function of rumen microbial populations. Knowledge of the rumen microbial ecosystem and its associated carbohydrases could enhance the likelihood of achieving positive responses to enzyme supplementation. The ability to sequence microbial genomes represents a valuable source of information in terms of the physiology and function of both culturable and unculturable rumen microbial species. The advent of metagenomic, metatranscriptomic, and proteomic techniques will further enhance our understanding of the enzymatic machinery involved in cell wall degradation and provide a holistic view of the microbial community and the complexities of plant cell wall digestion. These technologies should provide new insight into the identification of exogenous enzymes that act synergistically with the rumen microbial populations that ultimately dictate the efficiency of feed digestion.

Fibrolytic enzyme and ammonia application effects on the nutritive value, intake, and digestion kinetics of bermudagrass hay in beef cattle

The objectives were to compare the effect of exogenous fibrolytic enzyme (Biocellulase A20) or anhydrous ammonia (4% DM) treatment on the nutritive value, voluntary intake, and digestion kinetics of bermudagrass (Cynodon dactylon cultivar Coastal) hay harvested after 2 maturities (5- and 13-wk regrowths). Six individually housed, ruminally cannulated Brangus steers (BW 325 ± 10 kg) were used in an experiment with a 6 × 6 Latin square design with a 3 (additives) × 2 (maturities) factorial arrangement of treatments. Each period consisted of 14 d of adaptation and 7, 4, 1, 1, and 4 d for measuring in vivo digestibility, in situ degradability, no measurements, rumen liquid fermentation and passage indices, and rate of solid passage, respectively. Steers were fed hay for ad libitum intake and supplemented with sugarcane molasses and distillers grain (supplement total of 2.88 kg DM/d). Enzyme did not affect the nutritional composition of hay but ammonia treatment decreased hay NDF, hemicellulose, and ADL concentrations and increased the CP concentration particularly for the mature lignified 13-wk hay. The enzyme increased NDF and hemicellulose digestibility of the 5-wk hay but decreased those of the 13-wk hay. Ammoniation decreased intake of hay but increased digestibility of DM, OM, NDF, hemicellulose, ADF, and cellulose and increased the ruminal in situ soluble and potentially digestible fractions and the rate of DM degradation of the 13-wk hay. Also, ammoniation increased the concentrations of ruminal NH3, total VFA, acetate, and butyrate but enzyme treatment did not. Neither enzyme addition nor ammoniation affected rate of liquid and solid passage. In conclusion, ammoniation decreased the concentration of most fiber fractions, decreased the intake of hays, and increased their CP concentration, in vivo digestibility, and in situ degradability at both maturities whereas enzyme application increased fiber digestibility of the 5-wk hay but decreased it in the case of the 13-wk hay.

The effect of glycerol on mRNA expression of growth hormone, insulin-like growth factor, and mitochondrial breast muscle genes of Japanese quail

1. A study was carried out to evaluate the expression of growth hormone (GH), insulin-like growth factor I (IGF-I), mitochondrial adenine nucleotide translocase (ANT), cytochrome oxidase III (COX III) and avian uncoupling protein (avUCP) genes in 14-d-old Japanese quail that were fed different levels of glycerol (0%, 4%, and 12% dietary glycerol) which replaced maize as an energy source. 2. Total RNA was extracted from the breast muscle, and cDNA was amplified using real-time PCR with primers specific to the examined genes. 3. Quail fed the diet with 12% glycerol supplementation presented higher growth hormone (GH) mRNA expression than did those fed 0% glycerol. Supplementation with 12% glycerol negatively influenced IGF-I mRNA expression and reduced ANT mRNA expression in comparison with the treatment with no glycerol. COX III mRNA expression in the pectoralis superficialis muscle was decreased by 26% in quail fed 12% glycerol compared with those fed 0 and 4% glycerol. 4. There was no difference in UCP mRNA expression between quail fed 0 and 4% glycerol; however, UCP expression was reduced (73%) in birds fed the 12% glycerol diet compared with the level in those fed the 4% glycerol diet. 5. The inclusion of 4% glycerol in the diet produced results similar to those of the diet with no glycerol. Based on quail performance and the expression of the GH, IGF-I, ANT, COX III and UCP genes, 4% glycerol can be used in quail feeding without any harmful effects.

Characterization of an acid-tolerant β-1,4-glucosidase from Fusarium oxysporum and its potential as an animal feed additive

An extracellular β-glucosidase (BGL) from Fusarium oxysporum was purified to homogeneity by a single chromatography step on a gel filtration column. The optimum activity of BGL on cellobiose was observed at pH 5.0 and 60 °C. Under the same conditions, the K(m) and V(max) values for p-nitrophenyl β-D-glucopyranoside and cellobiose were 2.53 mM, 268 U mg protein(-1) and 20.3 mM, 193 U mg protein(-1), respectively. The F. oxysporum BGL enzyme was highly stable at acidic pH (t 1/2 = 470 min at pH 3). A commercial BGL Novo188 (Novozymes) and F. oxysporum BGL were compared in their ability to supplement Celluclast 1.5 L (Novozymes). In comparison with the commercial Novo188 (267 mg g substrate(-1)), F. oxysporum BGL supplementation released more reducing sugars (330 mg g substrate(-1)) from cellulose under simulated gastric conditions. These properties make F. oxysporum BGL a good candidate as a new commercial BGL to improve the nutrient bioavailability of animal feed.