Effect of cellulase,phytase and pectinase supplementation on growth performance and nutrient digestibility of rainbow trout (Oncorhynchus mykiss,Walbaum 1792) fry fed diets containing canola meal

This experiment was conducted to evaluate the effects of supplementing exogenous enzymes on growth, feed conversion ratio (FCR) and apparent nutrient digestibility in rainbow trout (Oncorhynchus mykiss) fry diets containing 32% canola meal. Five experimental diets (including a control diet containing no enzymes) were prepared as isonitrogenous (44% crude protein) and isocaloric (4000 kcal DE kg¹). The four other diets contained either cellulase, phytase, pectinase or an enzyme mix (a mixture of cellulase, phytase and pectinase in the same ratio). The feeding trial was conducted in triplicate for 12 weeks in 15 tanks (100‐L). At the beginning of the experiment 20 rainbow trout fry (initial weight 1.23 g) were stocked into each tank. Mean water temperature in the rearing tanks was 11°C and water flow in each tank was 6 L min^?1. At the end of the experiment the growth parameters and FCR displayed no significant differences in enzyme supplementation (P > 0.05). In addition, no differences were observed in dry matter, protein, or lipid digestibility with enzyme supplementation (P > 0.05). The results of this study showed that the addition of pectinase, phytase, cellulase or an enzyme mix to a diet containing 32% canola meal had no effect on growth, feed efficiency or dry matter, protein, or lipid digestibility in rainbow trout fry.     

Enzyme supplementation of wheat-based diets for broilers: 2. Effect on apparent metabolisable energy content and nutrient digestibility

Two experiments were conducted to determine the effect of enzyme supplementation on the nitrogen-corrected apparent metabolisable energy (AME_n) and apparent nutrient digestibilities in ileum and excreta from male broiler chickens fed diets containing high amounts of wheat (>80%). Four different enzyme preparations were added to the wheat-based diets in varying levels and combinations. The difference between Experiments 1 and 2 consisted in the addition of different enzymes and enzyme levels. Excreta and ileal content were collected from broiler chickens at 3 and 6 weeks of age. At 3 weeks of age enzyme supplementation increased (P<0.0001) the AME_n from an average value of 13.86 MJ kg⁻¹ dry matter (DM) to an average of 14.60 MJ kg⁻¹ DM in the two experiments. The apparent digestibility of protein (APD) and fat (AFD) were improved significantly as a result of enzyme addition in both experiments. At 3 weeks of age, improvements (P<0.05) in the ileal AFD and APD were on average 13% and 6%, respectively. The effect of enzyme supplementation on AFD measured in excreta from broiler chickens showed the same pattern. The positive effect of enzyme addition on the overall nutrient digestibility and AME_n was reflected in weight gain and feed conversion efficiency (FCE). Significant improvements in AME_n, APD, and AFD were still present in most of the groups fed with enzyme-supplemented diets at 6 weeks of age. The effect of enzyme addition, however, was less pronounced, especially in Experiment 1 where the ileal APD of broiler chickens did not differ significantly from the control group. Apparent starch digestibility (ASD), measured in Experiment 2, was very high in all groups, including the control; however, enzyme supplementation increased ASD (P<0.001) in ileum and excreta at both 3 and 6 weeks of age. The digestibility of total non-starch polysaccharides (NSP) in excreta was improved significantly (P<0.01) as a result of enzyme supplementation (Experiment 2). In addition, pH of caeca content decreased (P<0.02) in broiler chickens fed with enzyme-supplemented diets when compared with the control group. Decreased pH could indicate microbial fermentation of unabsorbed NSP residues and nitrogenous compounds. Overall, the results demonstrated that the nutritive value of wheat-based diets to broiler chickens improve enzyme supplementation. The apparent digestibility of total NSP and of arabinose and xylose residues improved (P<0.02) in the enzyme-supplemented diets indicating that the enzymes were able to break down the cell wall NSP to a certain extent.     

Influence of increasing levels of β-glucanase on the productive value of barley diets for broiler chickens

The influence on the productive value of diets for broiler chickens based on barley harvested at two stages of ripeness, when including β-glucanase in increasing amounts, was evaluated in a production experiment over three weeks. Feed consumption and live weight increased (P < 0.001) and feed conversion was improved (P < 0.001) by including β-glucanase in the diets. Dry matter content of excreta increased significantly as a result of β-glucanase inclusion. Broiler chickens receiving diets based on barley harvested at combine ripeness were slightly heavier (P < 0.05) at three weeks than those fed on barley harvested at early yellow ripeness.     

Enzyme supplementation of wheat-based diets for broilers: 1. Effect on growth performance and intestinal viscosity

The influence of enzyme supplementation on performance and intestinal viscosity of male broiler chickens fed with diets containing high amount of wheat was examined in three experiments. In the first experiment, addition with an enzyme preparation including different cell wall degrading enzymes to diets containing 63 g kg⁻¹ and 72 g kg⁻¹ of wheat improved (P<0.05) feed conversion efficiency in the 72 g kg⁻¹ wheat diet. In addition, intestinal viscosity of chickens fed with the 72 g kg⁻¹ wheat diet was reduced (P<0.05). Weight gain and feed intake were not influenced by enzyme addition. In Experiments 2 and 3, the inclusion level of wheat in the diets was more than 80 g kg⁻¹ and four different enzyme preparations were used (two xylanase preparations, two mixed preparations). Overall, a significant effect on performance and intestinal viscosity of chickens was obtained as a result of enzyme supplementation in both experiments. In the first 21 days, improvements (P<0.05) in weight gain and feed conversion efficiency were found to be on average 5% and 6% in Experiment 2 and 7% and 8% in Experiment 3, respectively. When weight gain and feed conversion efficiency were examined on a weekly basis it was shown that the significant response of enzyme addition was confined to the first 4 weeks. However, the effect of enzyme supplementation was still significant in the whole period from 21–42 days. Feed intake was not influenced by enzyme addition. The viscosity of intestinal content in both the jejunum and ileum was in general reduced (P<0.05) with enzyme supplementation, the xylanase preparations proving to be the most efficient. It was concluded that enzyme supplementation of wheat-based diets resulted in improved performance of broiler chickens, which was related to a concomitant reduction in intestinal viscosity. However, the response of enzyme supplementation was most pronounced in diets with a wheat content higher than 80 g kg⁻¹.     

Effect of fungal enzyme mixture supplementation of various fibre-containing diets fed to broiler chicks 1: Performance and carcass characteristics

Partially purified enzymes: amylase of Macrophomina phaseolina, cellulase of Trichoderma sp. and pectinase of Fusarium trincitum were produced, purified and mixed together to form a three-enzyme system. A similar mixture was produced for the crude forms of the three enzymes. The two forms of the enzyme mixture were then applied to diets containing wheat bran, rice bran, palm kernel meal, corn bran or coconut meal and were fed to 784 1-day-old broiler chicks of both sexes. Results after six weeks showed the live weight, the body weight gain and the feed conversion ratio to be significantly affected by enzyme supplementation for all fibre types included in the diets. Over the feeding interval, the plucked weight, carcass weight, edible meat and the total bone weight also increased in amount for both crude and partially purified forms of the enzyme applied directly or in water, compared with the unsupplemented diet. Statistically significant differences P(0.05) also existed in the percentage protein and ash content of the carcass of both the unsupplemented and supplemented diets.     

Role of Melanin in Release of Extracellular Enzymes and Selection of Aggressive Isolates of Bipolaris sorokiniana in Barley

Eighteen barley isolates of Bipolaris sorokiniana belonging to wild and clonal type of black, mixed and white subpopulations were quantitatively assayed for their melanin content and aggressiveness with respect to production of some of the extracellular enzymes such as cellulase, pectinase, amylase and protease. Cellulase and pectinase constituted major portion of the enzymes recovered from the black, mixed and white isolates. Enzyme production and aggressiveness were relatively higher in melanin devoid or low melanin isolates. The melanin deficient isolates were also differentiated from black and mixed isolates on the basis of variation in internal transcribed spacer region of the ribosomal DNA. Higher enzyme productions positively correlated with area under disease progress curve (AUDPC) and lesion development. Melanin content was negatively correlated with extracellular enzymes and aggressiveness of the isolates. Based on melanin content, lesion size, AUDPC and extracellular enzymes, the isolates were grouped in two major clusters (I and II) with further division of cluster II into two sub-clusters (II-A and II-B). The results appears to indicate a possible role of melanin in release of extracellular enzymes and hence in evolution and selection of aggressive isolates of B. sorokiniana in barley.     

Feeding value of field beans (Vicia faba L. var. minor) with and without enzyme containing tannase,pectinase and xylanase activities for broilers

Effects of field beans with various tannin content and exogenous enzyme mixture containing tannase, pectinase and xylanase activities on N-corrected dietary apparent metabolisable energy (AMEn), coefficients of dry matter (DMR) and nitrogen retention (NR), fat digestibility, gastrointestinal tract (GIT) development, jejunal villus morphometry, ileal digesta viscosity and sialic acid were examined. Birds’ growth performance and energy conversion ratio (ECR) were also measured. Birds were fed one of eight mash diets. The Control diet contained as major ingredients wheat (400 g/kg) and soybean meal (SBM) (127 g/kg and 221 g crude protein/kg and 12.83 MJ AMEn/kg. To reduce nutrient density, the Control diet also contained washed sand at 119 g/kg. Another three diets containing 300 g/kg of each of three experimental field bean cultivar samples in replacement for SBM and sand were also mixed. Each diet was fed to nine pens with two male Ross 308 broilers. Diets high in tannin had low AMEn, ECR, DMR and NR (p < 0.001). Feeding field beans increased (p < 0.001) the weights of the pancreas and the proventriculus and gizzard (PG) of the birds. Supplementing diets with the enzyme mixture improved (p < 0.001) feed conversion efficiency, AMEn and all nutrient utilisation coefficients despite the tannins in diets. The enzyme mixture reduced ileal digesta viscosity (p < 0.001) and the weight of pancreas, total GIT and PG (p < 0.05) of the birds. It can be concluded that the feeding value of field beans with different tannin contents may vary when fed to broilers. The supplementation of the enzyme mixture improved the feeding value of diets for broilers. The beneficial effect of the addition of the enzyme mixture seems to be mediated through reduced ileal digesta viscosity and improved nutrient availability.     

Use of enzymes to improve nutrient availability in poultry feedstuffs

Enzyme supplementation of cereal-based diets can significantly improve chick performance by increasing the rate of gain, efficiency of feed utilization, the apparent metabolizable energy and digestibilities of dry matter, fat and protein, with excellent improvements being obtained with diets containing rye, oats and barley. Less dramatic results are often obtained with wheat. In addition, enzyme treatment decreases the moisture content of excreta, which, together with improved dry matter digestibility, reduces the total amount of excreta produced and therefore reduces management and environmental problems. Enzyme supplementation also improves the nutritional value of lupins, and reduces the length and size of various sections of the gastrointestinal tract and the size of the pancreas of chickens. Dose-response studies with different amounts of supplemental enzymes when added to a rye-based diet demonstrated that there was a high linear correlation (r²>0.91, P < 0.05) between the concentration of enzyme when transformed into its logarithmic values and the corresponding improvements in weight gain or the feed-to-gain ratio. The log-linear model shows that for every ten-fold increase in the amount of enzyme in the diet there was a two-fold and not a ten-fold incremental improvement in chick performance. These studies suggest that there is a simple relationship between the amount of enzyme added to the diet and the resulting improvements that are obtained. Overall, enzymes when properly used can produce significant improvements in chick performance and can reduce the excretion of undigested nutrients.     

兽用博落回散对饲用酶制剂酶活性的影响

博落回散能抑菌消炎、改善畜禽肠道内环境,兼具营养和药用双重作用,已经成为一类新型饲料添加剂。酶制剂是目前已在养殖业广泛使用的饲料添加剂,它能提高动物对饲料的消化利用率、提高饲料转化率、降低饲喂成本。博落回散能否和酶制剂同时使用目前尚未有相关的研究报道。本文研究了不同浓度博落回散溶液对8种常用饲用酶制剂活性的影响,实验结果表明,在正常使用浓度(30～50 mg/L)范围内,博落回散不会明显影响淀粉酶、纤维素酶、果胶酶、甘露聚糖酶和木聚糖酶这5种糖基水解酶的活性;对植酸酶、酸性蛋白酶和脂肪酶这3种非糖基水解酶的活性影响不大,这说明博落回散能和酶制剂同时添加到饲料中。本研究为兽用博落回散饲料添加剂在养殖行业的广泛应用提供了实验支持。     

Lupin as primary protein source in young broiler chicken diets: Effect of enzymes preparations catalyzing degradation of non-starch polysaccharides or phytates

This work examined the effects of three enzyme preparations (A,B,C) directed towards degradation of Non Starch Polysaccharides (NSP) and one targeting phytates (D) on performance traits in broilers fed maize meal basal diets containing 400 g/kg of yellow lupine seeds (LM). A soybean meal (SBM) based diet served as a reference control. Growth rate, coefficients of total tract apparent digestibility (CTTAD) of organic matter, protein and energy, as well as morphometric measurements of selected sections of gastrointestinal tract (GIT) were determined. In comparison to chickens fed the SBM diet, chickens fed the LM diet consumed less feed, had considerably lower body weight gain, as well as lower CTTAD of measured nutrients and energy. Also the GIT relative weight and length were increased within the group fed the LM diet. Addition of each NSP degrading enzymes (A,B,C) to the LM diet increased feed intake and decreased size of GIT organs (all p < 0.05). Addition of enzymes A or B increased (p < 0.05) growth rate of chicks, whereas only enzyme B increased fed efficiency (p < 0.05) and tended to slightly improve CTTAD of nutrients. The addition of enzyme D did not have any effect on feed intake, growth rate or CTTAD. This study indicates that a diet containing high levels of LM is detrimental to feed intake and condition of the digestive tract of young broilers, and thus affects their performance. However, when the LM diet is supplemented with suitable enzyme preparations, performance parameters are not different from those obtained with SBM.     

Dietary essential oils improve feed efficiency and hepatic antioxidant content of broiler chickens

The aim of this study was to test the hypothesis of an improved growth, dietary nutrient availability and overall health of broiler chickens reared on recycled litter when fed a standardised combination of essential oils (EO; carvacrol, cinnamaldehyde and capsicum oleoresin). To assess the effect of dietary treatments, feed intake, weight gain, feed efficiency, availability of dietary nutrients and energy, villus morphometry, excreta sialic acid concentration, hepatic antioxidants and serum amyloid A (SAA) when fed to broiler chickens were evaluated. Counts of Eimeria spp. oocysts were also determined in excreta samples. Four experimental diets were offered, including two basal control diets based on either wheat or maize that contained 215 g CP/kg and 12.13 MJ/kg metabolisable energy and another two diets using the basal control diets supplemented with the EO combination at 100 mg/kg diet. Each diet was fed to eight floor pens, containing two birds each, following randomisation. Birds fed the EO-supplemented diets had an improved (P<0.05) feed conversion ratio (FCR). Birds fed maize-based diet had an improved daily weight gain and FCR (P<0.05) compared with wheat-fed birds. Wheat-based diet tended (P=0.056) to have greater N-corrected apparent metabolisable energy and had greater fat retention coefficient (P<0.05) compared with maize-based diets. No differences (P>0.05) were observed in villus morphometry, sialic acid secretion, number of oocysts and SAA. Feeding the EO improved (P<0.05) the retention of dietary Ca and Na. Compared with maize, feeding wheat-based diets improved the retention coefficients for Ca, P and Na (P<0.05). Feeding dietary EO improved (P<0.05) the concentrations of the hepatic antioxidants, including carotene, coenzyme Q₁₀ and total vitamin E. The hepatic concentration of carotene of the maize-fed birds was 55.6% greater (P<0.05) compared with the wheat-fed birds. These results demonstrated that the addition of a standardised combination of EO in wheat- and maize-based diets provided benefits in terms of feed efficiency, mineral retention and antioxidant status of the birds when reared on recycled litter.     

Effect of wheat dried distillers grains and enzyme supplementation on growth rates,feed conversion ratio and beef fatty acid profile in feedlot steers

The objectives of this study were to determine: (1) the effect of wheat dried distillers grain with solubles (DDGS) inclusion, and (2) dietary feed enzyme (FE; Econase XT) supplementation in a finishing diet containing wheat DDGS on fatty acid profile of the pars costalis diaphragmatis muscle of beef cattle. A total of 160 crossbred yearling steers with initial BW of 495±38 kg were blocked by BW and randomized into 16 pens (10 head/pen). The pens were randomly assigned to one of the four treatments: (1) control (CON; 10% barley silage and 90% barley grain-based concentrate, dry matter (DM) basis); (2) diet containing 30% wheat DDGS in place of barley grain without FE (WDG); (3) WDG diet supplemented with low FE (WDGL; 1 ml FE/kg DM); and (4) WDG diet supplemented with high FE (2 ml FE/kg DM). The pars costalis diaphragmatis muscle samples were collected from cattle at slaughter at the end of the finishing period (120 days) with a targeted live weight of 650 kg. No differences in organic matter intake, final BW and average daily gain were observed among treatments. However, steers fed WDG had greater (P<0.01) feed conversion ratio than those fed CON, and increasing FE application in wheat DDGS-based diets tended (P<0.10) to linearly decrease feed conversion ratio. In assessing the effects of including WDG diets without FE, concentration of total polyunsaturated fatty acids (PUFA) in muscle tended to be greater (P<0.10) for steers fed WDG than steers fed CON. In addition, inclusion of wheat DDGS into the diet increased (P<0.05) concentration of CLA and vaccenic acid (VA) in muscle and also resulted in a higher (P<0.05) ratio of n-6/n-3 PUFA compared with that from steers fed CON diet. Increasing FE application in wheat DDGS-based diets did not modify the concentrations of individual or total fatty acids. These results suggest that inclusion of wheat DDGS in finishing diets may improve fatty acid profile of beef muscle which could benefit human health.     

Incidence of leaf spot disease on cotton caused by <Emphasis Type="Italic">Curvularia verruculosa</Emphasis> and role of its hydrolytic enzymes in pathogenesis

The finding described in this study is the first report of leaf spot disease of cotton caused by Curvularia verruculosa surveyed in the state of Maharashtra (India). The isolated phytopathogenic fungal strain was identified using morphological characteristics and molecular identification of ITS gene sequence (MF784436) and D1D2 region of LSU gene (KY978073). The ability of fungal strain to secrete hydrolytic enzymes viz., pectinase, xylanase, protease, cellulase and lipase was detected. The secretion profile of hydrolytic enzymes by C. verruculosa was also examined in planta and in vitro. The secretion of cellulase, xylanase and protease was found to be inducible on cotton-stalk powder containing media; while secretion of pectinase and lipase was constitutive in glucose containing medium. The hydrolytic enzymes secretion during etiological progression of disease was detected on cotton leaves at regular interval of 24 h up to 10 days. A significant correlation (P < 0.05) was observed between hydrolytic enzymes secretion and disease severity index. The increased level of hydrolytic enzymes in infected plant sample indicates their role in disease progression. The newly documented fungal phytopathogen Curvularia verruculosa was deposited at National Fungal Culture Collection of India, Pune with accession number of NFCCI-4119.     

Activity of supplemental enzymes and their effect on nutrient utilization and growth performance of growing chickens as affected by pelleting temperature

Activity of supplemental enzymes in a barley‐soybean‐maize based diet at 60, 75 and 90°C pelleting temperatures was studied using feed viscosity, in‐vitro enzyme activity and broiler performance data.

High pelleting temperatures increased feed viscosity but supplemented enzymes reduced the viscosity at all three temperatures levels by 11, 14 and 17%, respectively. Water intake and losses in excreta of birds were found to be affected by feed viscosity. Activity of cellulase enzyme, measured using the radial diffusion method, was unaffected at 60 and 75°C, but reduced by 73% in feed processed at 90°C. Enzymes increased the weight gain of broilers by 11.1% at 90°C, but no effect could be seen at low pelleting temperatures possibly due to high dietary protein and energy contents. Feed intake was unaffected by enzymes. Birds consumed 6% more feed and grew 9% faster when the pelleting temperature was increased from 60 to 75°C. Reduced feed intake and daily weight gain observed at 90° C could be fully compensated by the enzyme supplementation. High pelleting temperature reduced energy metabolizability (3.2%) and nitrogen utilization (4%) but enzyme almost compensated them (by 3.3% and 2.6%, respectively). No interaction could be detected between the pelleting temperatures and enzymes.

It is concluded that pelleting temperatures as high as 90°C drastically reduce cellulase activity, energy and nitrogen utilization thus lowering broiler performance. Either the remaining activity of cellulase or other thermostable enzymes can prevent the losses.     

Influence of Butyrate Loaded Clinoptilolite Dietary Supplementation on Growth Performance,Development of Intestine and Antioxidant Capacity in Broiler Chickens

The study was conducted to evaluate the effects of dietary butyrate loaded clinoptilolite (CLI-B) on growth performance, pancreatic digestive enzymes, intestinal development and histomorphology, as well as antioxidant capacity of serum and intestinal mucosal in chickens. Two hundred forty 1-day-old commercial Arbor Acres broilers were randomly assigned to 4 groups: CON group (fed basal diets), SB group (fed basal diet with 0.05% sodium butyrate), CLI group (fed basal diet with 1% clinoptilolite), and CLI-B group (fed basal diet with 1% CLI-B). The results showed that supplementation of CLI-B significantly decreased (P < 0.05) feed conservation ratio at both 21 and 42 days of age, improved the pancreatic digestive enzymes activities (P < 0.05), increased the villus length and villus/crypt ratio (P < 0.05), and decreased the crypt depth of intestine (P < 0.05) as compared to the other experimental groups. Furthermore, the CLI-B environment improved the antioxidant capacity by increasing the antioxidant enzyme activities (P < 0.05) in intestine mucosal, and decreasing the NO content and iNOS activity (P < 0.05) in serum. In addition, CLI-B supplementation had improved the development of intestine and antioxidant capacity of broilers than supplementation with either clinoptilolite or butyrate sodium alone. In conclusion, 1% CLI-B supplementation improved the health status, intestine development and antioxidant capacity in broiler chickens, thus appearing as an important feed additive for the poultry industry.     

Morphological and Molecular Characterization of Pomegranate Fruit Rot Pathogen, <Emphasis Type="Italic">Chaetomella raphigera</Emphasis>, and its Virulence Factors

A new fungal pathogen was isolated from rotten pomegranates collected from the orchards of different parts of Maharashtra. The pathogen was morphologically identified as Chaetomella raphigera followed by sequencing of ITS and D1/D2 hypervariable region of LSU (28S) of rRNA gene. The pathogen produced pectinase, cellulase, xylanase and protease in liquid medium at a concentration of 71, 13.8, 54.3 and 7 U/ml respectively. Enzyme activity was also determined during pathogenesis in the tissues artificially infected by C. raphigera. Xylanase activity was maximum (25.1 U/g) followed by pectinase (19.2 U/g) and cellulase (1.5 U/g), whereas, protease activity was unnoticed. There was significant correlation (P < 0.05) between disease rating scale and pectinase, xylanase and cellulase activity in infected tissues. This indicates the simultaneous production of hydrolytic enzymes that aids in necrosis of fruit tissues. The elevated levels of these enzymes in infected tissues as compared with control suggest their possible role in pathogenesis. Thus, pectinase, cellulase and xylanase produced by C. raphigera acts as major virulence factors in the development of fruit rot in pomegranates. This is a first report of fungal fruit rot caused by C. raphigera in pomegranate.     

Characterization of major hydrolytic enzymes secreted by Pythium myriotylum, causative agent for soft rot disease

Pythium myriotylum, an oomycetous necrotroph is the causal agent of soft rot disease affecting several crops. Successful colonization by necrotrophs depends on their secretion of a diverse array of plant cell wall degrading enzymes (CWDEs). The induction dynamics of CWDEs secreted by P. myriotylum was analysed as little information is available for this pathogen. Activities of CWDEs that included pectinase, cellulase, xylanase and protease were detected using radial diffusion assay and differential staining. In Czapek Dox minimal medium supplemented with respective substrates as carbon source, the increase in CWDE activities was observed till 8 days of incubation after which a gradual decline in enzymatic activities was observed. With sucrose as sole carbon source, all the enzymes studied showed increase in activity with fungal growth while with cell wall material derived from ginger rhizome as sole carbon source, an initial spurt in cellulase, xylanase and pectinase activities was observed 3 days post incubation while protease activity increased from three days of incubation and reached maximum at 13 days of incubation. To further evaluate the role of CWDEs in pathogenicity, UV-induced mutants (pmN14uv1) were generated wherein significant reduction in cellulase, pectinase and protease activities were observed while that of xylanase remained unchanged compared to wild type isolate (RGCBN14). Bioassays indicated changes in infection potential of pmN14uv1 thereby suggesting the crucial role played by P. myriotylum CWDEs in initiating the rotting process. Hence appropriate strategies that target the production/activity of these secretory hydrolytic enzymes will help in reducing disease incidence/pathogen virulence.     

Hydrolysis of orange peel with pectinase and cellulase enzymes

Summary Hydrolysis of polysaccharides in comminuted orange peel by commercial cellulase and pectinase enzymes has been investigated. High levels of conversion to monomeric sugars were observed after treatment with pectinase enzyme, but cellulase enzyme achieved only limited solubilization. The combination of cellulase and pectinase enzymes appears to be a most efficient system for enzymatic hydrolysis of polysaccharides in orange peel.     

Influence of barley grain particle size and treatment with citric acid on digestibility,ruminal fermentation and microbial protein synthesis in Holstein calves

Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172±5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes×2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake (P=0.02) and average daily weight gain (P=0.01). The addition of CA to barley grain did not affect intake but increased weight gain (P<0.01) and improved feed to gain ratio (P=0.03). Digestibility of organic matter and NDF tended (P<0.10) to increase, whereas faecal scoring was improved (P=0.03) and the presence of undigested grain particles in faeces was reduced (P<0.01) with CA-treated barley grain. Glucose and urea concentrations were increased (P<0.01) in the blood of calves fed the CA-treated barley grain. Ruminal pH tended (P=0.08) to be decreased with more finely ground barley and was increased when barley grain was treated with CA. Total volatile fatty acid concentrations in the rumen did not differ among treatments (P>0.05). However, the molar proportion of propionate was increased (P=0.03) when barley was more finely ground, and that of acetate was increased (P=0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased (P<0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).     

Substrate specificity in the control of digestive enzymes in larvae of the black carpet beetle

When starved larvae of the black carpet beetle, Attagenus megatoma, were fed selected diets, increases in proteolytic, trypsin, and chymotrypsin activity were correlated with total midgut protein and not with the amount of food consumed. Although larvae initially consumed more of a starch diet than of 2 diets that contained added protein, total protease activity in these larvae was minimal. Starch-fed larvae and larvae fed a casein-sucrose diet had a consistently higher level of sucrase activity than larvae fed an all-casein diet. These total results support a secretagogue mechanism for control of digestive enzyme synthesis in insects. In addition, the absence of parallel stimulation of different digestive enzymes by a single substrate (starch) indicated nutrient class specificity in the control of inducible midgut enzymes in this species.