Abstract: Objective: The objective was to study effect of three natural microbial sources as additives on lamb performance, digestibility, feeding value some rumen and blood parameters, rumen cellulolytic bacteria counts as well as economical return. Methodology: Twenty four weaning Rahmany lambs averaged live 20.0±0.30 kg b.wt. were assigned to 4 similar groups (6 animals each), fed concentrate feed mixture and berseem (60:40%), (as a basal ration); (G1) Fed a basal ration without feed additives as control group, (G2) Fed the basal ration supplemented with 10 g per lamb per day of isolated bacteria (cellulolytic bacteria), (G3) Fed a basal ration plus 10 g per lamb per day of fibrozyme, (G4) Fed a basal ration with 10 g per lamb per day of yeast culture (Saccharomyces cerevisiae) during 24 weeks of growing period. Results: Indicated that there were significant differences in all nutrient digestibility, showing the lowest values with G1, while the highest values were obtained with G4. Furthermore, the rations with biological additives were (p<0.05) higher crude fiber digestibility. Animals fed isolated bacteria recorded the highest significantly values of cellulose, hemicelluloses and all cell wall constituents digestibility (%). Supplementing rations G2, G3 and G4 showed significantly high values of TDN and DCP% as well as digestible energy (Mcal kg–1 DMI) but no significant. Feed intake (kg per lamb per day) as DM was no significant difference while feed intake as TDN and DCP appeared to increase with supplemented rations compared with control ration. Data observed that body weight gain, average daily gain, feed efficiency were higher with biological additives rations. Total counts of cellulolytic bacteria in rumen were the highest (p<0.05) values in G2. Blood total protein and globulin for animals fed biological additives had higher values than those fed control ration (G1). The net revenue were 320, 228 and 226% (G4, G2 and G3, respectively). Conclusion: The biological additives can enhance lamb performance, digestibility and economic income with the superiority effect for adding yeast culture. Moreover, it can be enhance ruminal culture and fiber fraction digestibility with adding isolated bacteria with no side effects on physiological status.
INTRODUCTION
Tropical forages are rich in lignin and silica content, so carbohydrate has limited fermentation, the production of VFA and rumen microbial mass is decreased. The rumen digestion of forages is relatively slow and incomplete that lead to decrease animal performance and increase cost feeding livestock production (Bello and Escobar, 1997).
The manipulating of the microbial ecosystem in the rumen is more important to improve ruminant productive performance (Choi et al., 2012). There are various attempts have been used to optimize rumen microbial culture for example Direct Fed Microorganisms (DFM) are defined as a source of naturally microorganism (Krehbiel et al., 2003). The term DFM has included yeast, fungi, bacteria, cell fragments, enzymes and extracts (Sullivan and Martin, 1999). Their mode of action are variable on increasing substrate breakdown, enhancement of nutrient intake and promote growth. Although anaerobic bacteria, fungi and protozoa degrade cellulose in the rumen, cellulolytic bacteria plays the most important role for fibrolytic activity.
High concentrate diets affect on rumen pH, while, fiberolytic bacteria growth in rumen is strictly limited at pH (Russell and Wilson, 1996) less than 6.00. So, fibre digestion is not maximal under this dietary conditions. Murillo et al. (2000) reported that the benefit of enzyme supplementation is a least partially dependent on ruminal pH and Beauchemin et al. (2003) reported that adding enzymes to high-concentrate diets gave more improvement in animal performance than with high-roughage diets, which could be attributed mainly to improvements in ruminal fiber digestion. There are conflict among available researches for benefit or mode of action for natural microbial resources on rumen culture or rumen cellulolytic bacteria.
Therefore, the objective of the present study was to; (1) Evaluate the effect of adding different natural microbial feed resources (isolated bacteria, fibrozyme and yeast culture) on Rahmany lambs performance, (2) Investigate digestibility, feeding value and economic efficiency of the tested rations and (3) Count some strains of celluolytic bacteria in the rumen and determine some rumen and blood parameters.
MATERIALS AND METHODS
Experimental animal and rations: This study was carried out at El-Serw Research Station, belonging to Animal Production Research Institute, Agricultural Research Center. Twenty four growing Rahmany lambs averaged 20.0±0.30 kg LBW after weaning were assigned to 4 similar groups (6 animals each) according to their body weight. The feeding trial lasted 24 weeks. Animals were fed Concentrate Feed Mixture (CFM) and berseem at rate of 60:40% on DM basis, respectively (as a basal ration) according to NRC (1985). The animals were randomly assigned to receive the four respective rations as follow:
| G1: | Control ration (a basal ration) |
| G2: | A basal ration supplemented with 10 g isolated bacteria per head per day |
| G3: | A basal ration supplemented with 10 g commercial fibrozyme per head per day |
| G4: | A basal ration supplemented with 10 g yeast culture per head per day |
The isolated bacteria are cellulytic bacteria which secreting cellulase and xylanase enzymes (6×105 viable cells g–1 DM or cellulase enzyme 7.1 U g–1 DM and xylanase 2.3 U g–1 DM) according to Abd El-Galil (2000). Fibrolytic enzyme (fibrozyme) is compounded from Aspergillus niger, Trichoderma longibrachiatum, fermentation extracts and fermentation soluble. It contains 100 U xylanase g–1 according to Kung et al. (2000). Yeast culture are Saccharomyces cerevisiae 1×109 CFU g–1 DM.
The concentrate feed mixture consists of 34.0% zeamaize, 32.3% wheat bran, 20.0% undecorticated cotton seed meal, 10.0% soybean meal, 2.0% limestone, 1.0% sodium chloride, 0.5% minerals and vitamins mixture and 0.2% dicalcium phosphate. The CFM was offered to animals in 2 times daily just at 7 am and at 4 pm. While, the amount of berseem was divided into two equal parts and offered daily at 9 am and 6 pm. Fresh water and salt blocks were available for each group along the day. Amount of CFM and berseem were adjusted bi-weekly for each group according to increase in body weight. Each group was kept in separate shaded pen and fed as group feeding. Animals were weighed bi-weekly, while feed consumption, live weight gain, feed efficiency and feed costs per kg live body weight gain were calculated.
Digestibility trials and analytical methods: Four digestibility trials were conducted using three lambs from each group of feeding trial. Composite samples of feed and feces were analyzed according to AOAC (2000). Digestible Energy (DE) was calculated as according to NRC (1985):
DE (Mcal kg–1 DMI) = 0.04409×TDN%
where, DMI is dry matter intake and TDN is total digestible nutrients.
Rumen liquor samples were collected at 0, 3 and 6 h after morning feeding. Ruminal pH was immediately determined after rumen liquor was collected with a digital pH meter (pH ep®, pocket-sized pH meter Hana instruments, Italy). Concentration of NH3-N was immediately determined using micro-diffusion method of Conway (1963). Frozen rumen liquor samples were analyzed for Total Volatile Fatty (TVF’s) acids by steam distillation according to Warner (1964). Blood plasma samples were taken from jugular vein at the end of feeding trial at 0, 3 and 6 h post feeding from experimental animals and stored at -20°C till analysis. Plasma total protein, albumin and AST and ALT transaminase activities and creatinine were analyzed using commercial kits of Bio-Merieux, lab, France.
Bacterial cultures: Six strains of cellulolytic bacteria were isolated from rumen fluid of lambs after 0, 3 and 6 h from morning feeding then grown as pure culture. Rumen fluid was collected by stomach tube. The separated strains were Cellulomonas cellulasea, Bacillus sp., Thermonospora fusca, Acetobacter xylinum, Ruminococcus albus and Clostridium cellulovorans. The isolation of species used the pour-plate technique for pure preparation of cultures according to ATCC (1992). The rumen samples were immediately gassed with CO2 and viable counts of rumen cellulolytic bacteria were determined according to the method described by Moir (1951) and Gall et al. (1949) and their classification were done according to Pounden and Hibss (1948).
Economic evaluation: Economic efficiency was calculated according to the following equation:
Net revenue (LE per lamb per day) = Money output-Money input
Statistical analysis: Data were statistically analyzed using general linear model program of SAS (1999). Digestibility and performance data were analyzed as one way analysis of variance according to the following model:
Yij = μ+ti+eij
where, Yij is observation, μ is mean, ti is effect of treatment and eij is experimental error. The significance differences among treatments were tested by Duncan (1955).
RESULTS AND DISCUSSION
Chemical composition of experimental rations: Chemical composition and cell wall constituents of CFM, berseem and basal ration as control group (percentage on DM basis) are presented in Table 1.
| Table 1: | Chemical composition and cell wall constituents of feed ingredients and calculated chemical composition of basal ration (% on DM basis) |
| Table 2: | Nutrients digestibility and feeding values of experimental rations for growing lambs |
ADE (Mcal kg–1 DMI) = 0.04409×TDN%, SE: Standard error, a-cMeans in the same rows with different superscripts are significantly different at (p<0.05), G1: Control, G2: Isolated bacteria, G3: Fibrozyme and G4: Yeast culture | |
The data indicated that the crude fiber, crude protein and the ether extract were 16.43, 16.26 and 6.13% in the basal ration. It could be noticed that cell wall constituents were higher in basal ration than CFM. Percentage of NDF, ADF, hemicelluloses and cellulose content were 34.99, 18.44, 16.55 and 10.88%, respectively in the basal ration.
Digestion coefficient and feeding value: Data in Table 2 indicated that supplementing rations with isolated bacteria (G2), fibrozyme (G3) and yeast culture (G4) were significantly (p<0.05) increased DM and CF digestibility as compared with those of control ration (G1). These results are in the same line with those obtained by Pinos et al. (2000) who illustrated that NDF digestibility was increased in lambs fed xylanase and cellulose enzyme. The increase in digestibility coefficients, especially for CF digestibility might be due to increase in rumen microbial population (Newbold et al., 1996) and/or activity of rumen cellulolytic bacteria (Dawson, 1993).
| Table 3: | Counts of total cellulolytic bacteria and some cellulolytic bacteria species separately from rumen animals fed experimental rations |
| a-dMeans with different superscripts within each row for each parameter are significantly different (p<0.05), G1: Control, G2: Isolated bacteria, G3: Fibrozyme, G4: Yeast culture and *NS | |
It could be noticed that ration supplemented with yeast culture (G4) attained to be significantly (p<0.05) higher for CP and EE digestibility compared with those of control (G1) and the other supplemented rations G2 and G3. On the other hand, there were no significant differences in EE among animals fed rations G1, G2 and G3. While, value of CP digestibility for microbial additives groups (G2 and G3) had significant differences with G1, but the differences between G2 and G3 were not significant. These results are confirmed with Zinn and Salinas (1999) who reported that adding fibrolytic enzyme increased ruminal digestion of feed nitrogen by 5% which reflected on daily gain comparing with control ration. Furthermore, G3 and G4 supplementation had significant the highest digestibility values of DM, OM and NFE. Generally, all rations supplemented with feed additives recorded higher digestibility coefficients for all nutrients compared to no supplemented one (control).
These results indicated that adding yeast for ration (G4) increased value of CP digestibility, this may be due to consider yeast culture as a microbial protein. Thus, the improvement of protein digestibility with yeast culture supplementation may be due to the stimulation of rumen protelytic bacteria (Williams et al., 1991).
Digestibility coefficients of cell wall constituents are illustrated in Table 2. Data indicated that digestibility of NDF, ADF, ADL, hemicellulose and cellulose were achieved the highest (p<0.05) values in group supplemented with isolated bacteria (G2) being 85.12, 84.35, 84.91, 85.98 and 84.96%, respectively than others. On contrary, control ration (G1) showed the lowest (p<0.05) values, as shown in Table 2. Decreasing in cell wall constituents digestibility with G4 than G2 might be due to consider yeast as microbial protein and stimulate proteolytic bacteria so, it had slightly negative effect on digestion of fiber and cell wall constituents comparing with adding cellulolytic enzymes in G2 that stimulate the digestion of fiber and cell wall constituents. This confirmed with increasing of numbers of some strains of cellulolytic bacteria which isolated from rumen and total count of cellulolytic bacteria (Table 3) in group 2 compared with others. These results are in harmony with those recorded by Zinn and Salinas (1999) who showed that supplementing fibrolytic enzyme increased the ruminal digestion of NDF by 23%. While, yeast supplemented group (G4) was the lowest value of NDF, ADF, ADL, hemicellulose and cellulose than other supplemented groups with significant (p<0.05) differences. Furthermore, according to Gomez-Alarcon et al. (1987) who reported that improving CF digestibility may be due to the increasing number of rumen cellulolytic bacteria. Also, Yoon and Stern (1996) found that increasing DM, OM, CP and EE digestibility with animals fed microbial supplemented rations might be due to adding microbial supplements stimulated the growth and activity of certain ruminal microorganisms.
Robinson (1997) found that Yeast Culture (YC) improved the digestibility of most nutrients and reported that supplementation of YC in the diet increased net digestion in the four stomach, particularly of fiber leading to increase energy output. Chademana and Offer (1990) found that yeast culture increased the initial rate of forage digestion in the rumen.
Table 2 observed that the supplementation rations (G2, G3 and G4) recorded (p<0.05) high values compared with G1for feeding values as TDN% and DE (Mcal kg–1 DMI) showing significant difference for G3 and G4 in TDN% comparing with G1 and G2. El-Ashry et al. (2003, 2001) noticed that supplemented rations with yeast (p<0.05) increased feeding value of ration. Abd El-Galil (2014) found that feeding values as TDN for rations supplemented either fibrozyme or mix (fibrozyme+yeast) were significantly higher than that supplemented with yeast culture and the lowest values observed with ration without supplements. The DCP values were significantly (p<0.05) increased with G4 (13.66%) than those of other rations (G2, G3 then G1). Ration supplemented with yeast culture (G4) had the highest DCP% followed by those supplemented with fibrozyme and isolated bacteria, while the control ration (with no supplemented) had the lowest value. Abd El-Galil (2014) recorded that DCP% had significantly higher values with adding fibrozyme or mixed fibrozyme with yeast (8.15 and 8.01%) and ration with yeast (7.37%) than without additives (6.59%). Increasing DCP for rations supplemented with biological additives might be due to increase the number of bacteria in the rumen and increase the digestibility and feeding values in experimental diets and this reflected from results of CP digestibility which confirmed by Yoon and Stern (1996) who illustrated that proteolytic bacteria counts were stimulated by yeast culture.
Improving feed intake seems to be driven partly by an improved rate of fiber breakdown (Wallace and Newbold, 1992) and partly by an improved duodenal flow of absorbable amino nitrogen (Williams et al., 1990). The most effect of microbial feed additives is that increasing the viable count of anaerobic bacteria recovered from ruminal fluid by 50-100% (Wallace and Newbold, 1993). Cellulolytic bacterial numbers are increased (Wallace and Newbold, 1993) thus explaining the improvement in fiber breakdown and increasing stability of the fermentation in animals receiving yeast and A. oryzae (Harrison et al., 1988; Williams et al., 1991). Nitrogen balance and metabolism was found to be improved due to the inclusion of YC in the diet of sheep. This may have been due to the increase in N digestibility as well as a better utilization of the dietary, N. Proteolytic bacteria count was increased and the flow of non-microbial non-ammonia N tended to be higher for cows fed YC (Yoon and Stern, 1996; Putnam et al., 1997).
Growth performance: Table 4 showed that consumption of CFM and berseem were almost similar in all the tested rations. There was a slightly difference in daily total feed intake (kg per lamb) as DM between supplemented and control rations. However, intake as TDN was markedly increased with supplemented rations (0.894, 0.974 and 1.024 kg TDN for G2, G3 and G4, respectively) compared with control ration. With corresponding (0.822 kg TDN) observed for DCP values that being 0.183, 0.199, 0.201 and 0.215 kg for rations G1, G2, G3 and G4, respectively. These results are in harmony with results of Allam et al. (2001) who reported that there was a significant improvement in DM intake when yeast culture was given to lactating animals.
| Table 4: | Feed intake, body weight gains (kg) and feed efficiency for growing lambs fed experimental rations |
| a-dMeans in the same rows with different superscripts are significantly different at (p<0.05), G1: Control, G2: Isolated bacteria, G3: Fibrozyme, G4: Yeast and *NS | |
But disagreement with that reported by Ebtehag et al. (2011) who found that feed intake as DM, TDN and DCP did not affected with supplemented rations by yeast culture compared with control ration. Also, Hadjipanayiotou et al. (1997) reported that no effect of YC on DM intake.
Feeding animals with ration supplemented with isolated bacteria, fibrolytic enzymes or YC increase feed intake, however, differences were not tested statistically due to the group feeding system applied in the present study. However, Bowman et al. (2002) reported that the effects of fibrolytic enzymes on DMI appear to be vary among enzymes products and the method of applying enzymes.
Table 4 revealed that animals fed supplemented rations (G2, G3 and G4) had significantly higher in total and daily body weight gains than those fed control (G1). Average daily weight gains recorded the highest values with group fed yeast culture (G4) followed by those fed fibrozyme (G3) and isolated bacteria (G2), being 198.9, 190.5 and 171.6 g day–1, respectively. While, animals fed control ration (G1) recorded the least one 138.7 g day–1 as daily weight gain. These results were attributed to increase TDN and DCP intake. Thus, increasing the Digestible Energy (DE, Mcal kg–1 DMI) value and CP, CF digestibility (Table 2).
On average, microbial additives may benefit ruminant nutrition (in terms of live body weight gain) by a similar magnitude to ionophores with 7 or 8% improvement (Wallace and Newbold, 1993), in this case by increasing feed intake and feed efficiency (Williams and Newbold, 1990). The effects are highly variable, however and much remains to be established about the dose and diet-dependence of the effects. Increasing ADG resulting from adding enzymes was attributed to an increase in DMI and improvement in digestibility.
Table 4 noticed that feed efficiency as 1 kg gain per 1 kg DMI, TDNI and DCPI were higher with those fed supplemented ration with isolated bacteria, fibrozyme and yeast culture ration than those fed control ration being 0.192, 0196 and 0.194 kg gain kg–1 TDN feed intake and 0.862, 0.946 and 0.926 kg gain kg–1 DCPI, respectively, comparing with control ration (0.169 kg gain kg–1 TDNI and 0.759 kg gain kg–1 DCPI). The highest value of kg gain kg–1 DM feed intake (0.126) was recorded with yeast culture ration. These results were confirmed by Mohamed et al. (2013) who reported that improving feed efficiency indicates better utilization of nutrients when adding enzymes with the magnitude of improvement being a linear function of enzymes dosage. These results came on line with those obtained by Abd El-Galil (2008).
The DFM improves the intestinal microbial balance of host animal in favor of beneficial gut microflora (Cruywagen et al., 1996). It may also help prevent ruminal acidosis (Nocek et al., 2000) and can improve the feed efficiency and average daily weight gain of feedlot cattle (Rust et al., 2000). Abd El-Galil (2014) recorded that biological additives on basal diet for feedlot Baladi goats with fibrozyme and a combination of yeast culture and fibrozyme enhanced ruminal digestion and thereby enhanced dry matter intake and growth performance. Efficacy of adding biological additives on ration may due to growth types of microorganisms which improve efficiency of using diets.
Rumen parameters and cellulolytic bacterial count: Rumen parameters are illustrated in Table 5. Ruminal pH value is one of the most important factors, which affect microbial fermentation in the rumen and influenced its functions. The pH values were within the normal range with significant differences among tested rations at 0, 3 and 6 h post feeding, being the highest (p<0.05) values were occurred with G3 (fibrozyme) and G4 (yeast culture) over all sampling times comparing with other treatments. While, the pH values tend to decrease by prolongation of time post-feeding, reaching lowest at 3 h post-feeding then increased after 6 h feeding.
Ruminal pH affects fiber digestion through its influence on the specific growth rates of cellulolytic bacteria. Growth of cellulolytic bacteria is optimal at ruminal pH greater than 6.5.
| Table 5: | Rumen liquor parameters of growing lambs fed experimental rations |
a-cMeans followed by different letters in the same row are significantly different (p<0.05), G1: Control, G2: Isolated bacteria, G3: Fibrozyme and G4: Yeast culture | |
Between pH of 6.5-6.0, the specific growth rate decreases 14% h–1 for every 0.1 U decrease in ruminal pH. Cellulolytic bacteria do not grow at ruminal pH below 6.0 (Zinn and Salinas, 1999).
There were significant differences in TVFA’s value among the supplemented rations at different times compared with control ration. In the present study, increasing TVFA's concentration in rumen liquor for lambs fed rations containing biological additives (isolated bacteria, fibrozyme and yeast culture) may be due to increase in DM, OM, CF, CP and NFE digestibility than those of control ration. These results showed that the effect of biological additives on microbial fermentation for protein and fiber in the rumen could be reflected on microbial protein synthesis.
Consistently, the same trend was observed for rumen NH3-N which recorded significantly higher (p<0.05) values for G4 and G3 than G2 and G1. Over all observation, TVFA's and NH3-N values were higher in groups with biological additives (G2, G3 and G4) than control ration (G1), these means increasing rumen activity. These values were similar to that reported by Abd El-Galil (2006), who found that the highest ammonia N concentration recorded at 3 h post feeding. However, it is well recognized that the ammonia N concentration found in the rumen at any given time presented the net concentration value of its production after utilization by rumen microbes and absorption across the rumen wall, the dilution by other factor and passage to the lower gut. The above categorization on the basis of pH corroborates with the reports of Choudhuri et al. (1981). Yoon and Stern (1996) reported that control group (without YC) was the lowest values of NH3-N and TVFA's. This may have been due to the mode of action of YC in ruminal microbial activity that increasing bacterial counts and activity and the stability of the ruminal environment.
Cellulolytic bacteria counts under the different feeding regimens are given in Table 3. Total cellulolytic bacteria counts in rumen content were the highest (p<0.05) value in G2 followed by G4 and G3, while the lowest value was recorded with G1 (control diet). These result might be due to supplemented experimental ration with biological additives, causing enhance and stimulate activity of cellulolytic bacteria in rumen. These results clarify increasing values of CF digestibility and cellulose and hemicelluloses digestibilities. The same trend was observed for number of Cellulomonas, Thermonospora, Acetobacter, Ruminococcus and Clostridium which the highest significant (p<0.05) value was observed with G2 comparing to others while the lowest value was recorded for G1. Result revealed no significant differences of Thermonospora count in all groups ration, while the lowest value in control ration (G1) for number of all cellulolytic bacteria.
These results indicated that biological additives had effect on ruminal pH and TVF's values, as well as CP, CF, NFE digestibility and cell wall constituents digestibility in supplemented rations which led to growth different bacteria species in rumen particularly cellulolytic bacteria. The rumen microbial population is very sense, containing bacteria, protozoa and fungi, which could be somewhat changed according to the buffering processes by phosphate and bicarbonate from saliva and also bicarbonate from rumen fermentation. The percentage of Bacillus, Acetobacter and Clostridium from total cellulolytic bacteria were recorded the maximum for animals fed isolated bacteria (G2; 2.99%, 21.95 and 14.67%, respectively), while Cellulomonas was achieved the maximum at in (G3; 24.7%) which diet contained fibrozyme as additives.
In relation to these results, Weimer (1996) reported that the bacteria Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes generally are regarded as the predominant cellulolytic microbes in the rumen. They are able to utilize cellulose (or in some cases xylan) and its hydrolytic products as their nearly sole energy sources for growth. Active cellulose digestion involves adherence of cells to the fibers via a glycoprotein glycocalyx, which protects cells from protozoal grazing and adheres cellulolytic enzymes from degradation by ruminal proteases, while it retains-at least temporarily-the cellodextrin products for use by the cellulolytic bacteria. These properties result in different ecological roles for the adherent and no adherent populations of each species, but overall provide an enormous selective advantage to these cellulolytic bacteria in the ruminal environment. However, major constraints to cellulose digestion are caused by cell-wall structure of the plant (matrix interactions among wall biopolymers and low substrate surface area). The degradation of cellulose in particular requires several enzymes that are joined together in a molecular structure known as a cellulosome. The cellulosome to the surface of plant cell walls, providing the initial step in fibre breakdown (Krause et al., 2003).
Many of bacteria in the rumen are free-floating in the liquid just before feeding and become attached to new feed particles after feeding. It is very difficult to remove and count the bacteria attached to feed particles and thus may explain the low numbers observed in the rumen after feeding, when fermentation rate is generally at its greatest. Bacterial numbers are generally assumed to be higher on high concentrate diets compared to high forage diets (Hespell et al., 1997; Morgavi et al., 2010). However, there are more fluid-associated bacteria with high concentrate diets and thus, easier to enumerate. The biggest differences due to diet are in the type of bacteria rather than the total number. Varel and Dehority (1989) reported that the proportions of F. succinogenes, R. flavefaciens and R. albus in the total cellulolytic bacteria in cattle rumen were 33.0, 2.6 and 46.0%, respectively. In addition, the ability of these three species to digest cellulose is much higher than that of other cellulolytic ruminal species. Therefore, F. succinogenes, R. flavefaciens and R. albus have been considered representative cellulolytic bacterial species in the rumen.
The ability of yeast to stimulate the viable count in the rumen depends on its respiratory activity (Newbold et al., 1993). Regardless of the efficacy or mode of action of microbial feed additives. It is already in widespread use. It may offer new opportunities for manipulation.
Dawson (1993) reported that there were strains of yeast that stimulate the growth of specific types of bacteria, thus leading the development of additives suitable for different dietary circumstances. In addition, the rumen bacteria change qualitatively and quantitatively in response to the changes in chemical composition of diet (Maklad and Bahira, 2001). The main effect of yeast culture is to stabilize the rumen environment. Concentrations of cellulolytic and anaerobic bacteria were higher in in vitro and in vivo systems.
Blood parameters: Table 6 showed that blood total protein, albumin, globulin, AST, ALT and creatinine. Blood total protein values were\significantly higher (p<0.05) records (5.04, 5.14 and 5.40 g dL–1) for animals fed rations containing biological additives (G2, G3 and G4) than control ration (4.55 g dL–1, G1). This was reflects on total body gain. On the other hand, values of blood albumin were no significant difference among tested rations, but values increased with supplemented rations. This might be associated with improved nitrogen absorption (Talha et al., 2009).
| Table 6: | Some parameters of blood from growing lambs fed experimental rations |
| a-cMeans in the same rows with differ rent superscripts are significantly different at (p<0.05), *NS | |
| Table 7: | Economical efficiency of growing lambs fed experimental rations |
Price of feedstuffs and supplementation: 2400 LE t–1 of Concentrate Feed Mixture (CFM) and 400 LE t–1 on of berseem, 10 LE kg–1 of isolated bacteria, 35 LE kg–1 of yeast culture, 75 LE kg–1 of fibrozyme and price of meat: 35 LE kg–1 live body weight, 1$US: 7.20 LE (Egyptian pound), ANet revenue (LE per lamb per day): Money output-money input, BEfficiency: Money output/money in put | |
Increasing blood albumin suggested normal status of liver function, since liver is the main organ of albumin synthesis. In addition, blood globulin (g dL–1) value for G4 were significantly higher than those of G2, G3 and G1. The blood creatinine, AST (IU L–1) and ALT (IU L–1) values had no significant differences (p>0.05) among all diets. However, all previous parameters showed slightly higher values with supplemented rations (G2, G3 and G4) than that of control ration (G1). These mean that biological additives not affected on kidney function as creatinine or liver function as AST and ALT concentration. Dimova et al. (2013) found that no significant differences (p>0.05) in plasma creatinine concentration due to probiotic supplements. Blood creatinine level is a useful indicator of filtration in the kidney and normal concentration of creatinine indicates the optimal physical activity. Generally, the increase in blood constituents might be due to the role of biological additives in improving all nutrient digestibility and rumen parameters of lambs fed supplemented rations (G2, G3 and G4) and also might be probably led to an increase in the absorption rate from the digestive tract, thus blood constituents of animals fed supplemented rations were reflection of the regime of diets.
These results were agreement with those obtained by Abd El-Galil (2008). The Direct-Fed Microbial (DFM) improved the intestinal microbial balance of ruminants microflora (Cruywagen et al., 1996). In addition, Hutjens (1991) refers to expected performance changes when animals fed on a feed additive, who mentioned to greater DM intake, stimulate rumen microbial synthesis, increase digestibility, stabilize rumen environment and pH and improve health (less ketosis, reduce acidosis and increase immune response). It can be improve the feed efficiency and average live daily weight gain of cattle fed supplemented feed (Rust et al., 2000) and may prevent ruminal acidosis (Nocek et al., 2000). The present results of blood parameters were in same line with those obtained by Abd El-Galil (2014) and Abou-Elenin et al. (2015).
Economic evaluation: Regarding the economic evaluation (Table 7), results indicated that feed cost to produce 1 kg gain was better with animals fed isolated bacteria ration (G2) followed by those fed yeast culture (G4), comparing with control ration (G1); being 2.03, 2.18 and 2.26 LE kg–1 gain, respectively. The highest net revenue (LE per lamb per day) was shown with yeast culture (G4) followed isolated bacteria (G2) ration then fibrozyme (G3) rations in comparison with control ration. The increasing rates of net revenue were 320, 228 and 226% with animals fed supplemented rations (G4, G2 and G3, respectively), comparing with control ration (100%). It could be noticed that, the economic efficiency recorded higher value with yeast culture (G4) followed by isolated bacteria (G2), while control ration (G1) was the lowest value. The present study showed that the inclusion of fibrozyme as a feed additive into the diets of ruminants is currently not economically feasible comparing with tested rations with other biological additives.
Overall, recent data indicated that microbial additives might benefit ruminant nutrition in terms of live weight gain and milk production (Abou-Elenin et al., 2015) by a similar magnitude to ionophores being 7 or 8% improvement (Wallace and Newbold, 1993) and by increasing feed intake rather than feed efficiency (Williams and Newbold, 1990). In recent study, Castillo-Gonzalez et al. (2014) concluded that the use of additives can manipulate the ruminal ecosystem and ruminal microflora in order to improve production. Because ruminal microorganisms are crucial for proper animal nutrition, it is important to generate innovative knowledge in the study of ruminal fermentation and microbial ecosystems to improve the ruminant feeding process. Therefore, the use of additives in the diet to improve the efficient use of nutrients and thus reduce the final products cost that affect the atmosphere are being important.
CONCLUSION
Results of this study concluded that adding isolated bacteria, fibrozyme and yeast culture as feed additives in growing Rahmany lambs rations could be enhancing nutrients digestibility, feeding values, daily gain and feed efficiency with no side effects on physiological status. Moreover, biological additives increased total number of cellulolytic bacteria and some strains of fibrolytic bacteria particularly by using isolated bacteria. While, yeast culture had the significant superiority (p<0.05) in improving digestibility, feed efficiency and economic income.
ACKNOWLEDGMENT
Authors are appreciating and thanking for Animal Production Research Institute (APRI) belonging to Agricultural Research Center (ARC), Agriculture Ministry in Egypt to fund, support and help authors to conduct this study.
SIGNIFICANT STATEMENTS
Most forage contains cellulose, hemicelluloses and lignin, it has limited digestion and slow rumen degradation that lead to decrease animal performance and increase cost feeding livestock production.
| • | There are many biological additives but its cost is the limitation of using it |
| • | So, conducting this study to comparing of effect of using different biological resources: Local isolated bacteria, commercial mixed enzymes or yeast culture on animal performance and rumen culture as well as economically return |
| • | This study revealed that adding yeast culture is the best economically but isolated bacteria was the more effective on fiber digestion and rumen culture with no side effects on physiological state |