Abstract: The present study aims to evaluate the effets of in-activated and dried yeast on Barki lambs. For that purpose thirty growing Barki male lambs (averaged 27 kg body weight, 9 months old) were divided into 3 groups (10 in each) according to live body weight for 90 days trial to study the effects of yeast supplementation on digestibility, growth performance, blood and rumen liquor parameters. The treatments contained 0 yeast (T1), 5 g h-1 day-1 either of inactivated yeast (T2) or dried yeast (T3). Results showed that the digestibilities of most nutrients and fiber fraction, nutritive value as TDN, total and average daily gain and feed conversion efficiency were improved by supplementation of inactivated yeast, followed by dried yeast compared to control. However, no differences (p<0.05) were observed in rumen pH and ammonia N. There were any adverse effects on blood parameters due to yeast supplementation. Based on this experiment, yeast supplementation (5 g h-1 day-1) especially with inactivated yeast could be recommended to improve growth performance of growing lambs.
INTRODUCTION
In animal feeding, probiotics such as live yeast are being explored as a substitute of antibiotic feed additives that improves gut media, promotes animal performance and limits excretion of pollutants.
Active yeast supplementation had positive effects on performance of young ruminants through increasing dry matter intake, body weight gain and feed efficiency (Lesmeister et al., 2004; Stella et al., 2007). Many researchers investigated the mode of action of yeast which could be summarized by: (1) Improvement in rumen development parameters, such as papillae length and width and/or rumen wall thickness (Lesmeister et al., 2004); (2) Increasing animal production by increasing the net energy of the ration (Robinson, 1997); (3) Reducing effect on diarrhea (Galvao et al., 2005) by stabilization of rumen microbial communities (Chaucheyras-Durand and Fonty, 2001, 2002); (4) Maintaining a higher rumen pH (Bach et al., 2007) in ruminants fed high grain ration as a result of increasing lactate utilizing bacteria counts and (5) Production of one or more extracellular compounds which inhibit some pathogenic bacterial strains such as proteases (Comitini et al., 2005).
On the other hand, Agarwal et al. (2002), Erasmus et al. (2005), Mahender et al. (2005), Kim et al. (2006), Kawas et al. (2007) and Tripathi et al. (2008) found similar or reduced growth rate compared to the control. The variable and inconsistent results could be attributed to biotic factors such as strain and viability of yeasts and a biotic factors such as nature of the diet and animal management conditions (Chaucheyras-Durand et al., 2008). Nikpiran et al. (2013) found that prebiotic (Thepax) has positive effects on performance in Japanese quails.
The objective of this study was to investigate the effects of yeast supplementation either inactivated (Thepax®) or dried yeasts (Yeastmax®) in sheep ration on digestibility, nutritive value, performance, some blood and rumen liquor parameters.
MATERIALS AND METHODS
Experimental animals and ration: Ninety days of growth trial, thirty Barki lambs averaged (27 kg) body weight; 9 months old were divided into 3 groups (10 animals each) according to their live body weight. The experimental groups were offered concentrate feed mixture and clover hay (divided into 70% CFM and 30% roughage) to cover total requirements according to NRC (1985). Animals in the control group T1 were fed clover hay plus concentrate feed mixture (CFM) without additives. While, animals in T2 and T3 group were fed control ration plus inactivated yeast (Thepax®) and dried yeast (Yeastmax®), respectively.
The concentrate feed mixture (CFM) consisted of 65% whole yellow corn, 15% wheat bran, 15% soybean meal, 1.2% premix, 0.8% common salt and 3% limestone.
The commercial inactivated yeast (Thepax®) and dried yeast (Yeastmax®) used in this study were mixed manually with CFM daily at the ratio of 5 g h-1 day-1.
Dry yeast Yeastmax® (1x105 CFU g-1) was from Unipharma company, Egypt and the patent new inactivated Saccharomyces cerevisiae Var. ellipsoideus Doxal strain’s Thepax®, (1x1010 CFU g-1) was from Doxal company, Italy and Elyoser medicine trading company, Egypt. Thepax® is made of killed and stabilised suspension of Saccharomyces cerevisiae Var. ellipsoideus. It included enzymes, vitamins (B1, B2, B6, B12, PP, pantothenic acid, biotin), amino acids and minerals (calcium, magnesium, sodium, potassium, phosphor, copper, iron, zinc and manganese) (Ayed and Ghaoui, 2011). The chemical composition of concentrate feed mixture, clover hay and calculated experimental ration are presented in Table 1.
| Table 1: | Chemical composition of the concentrate feed mixture, clover hay and experimental ration |
| CFM: Concentrate feed mixture (65% whole yellow corn, 15% wheat bran, 15% soybean meal, 1.2% premix, 0.8% common salt and 3% limestone), CH: Clover hay | |
Feeding procedures: The growing lambs were fed (in groups) CFM and forage twice daily and water was allowed freely all the day round. Orts were collected just before offering the next day’s feed. Lambs were weighed every two weeks before morning feeding after 15 h of fasting. The CFM was adjusted every two week according to body weight changes. Feed intake was recorded, daily body weight gain and feed efficiency (g feed/g gain) were calculated.
Digestion trials: At the end of growth trial, three rams from each group was used to evaluate the experimental rations through digestion trials (21 days for adaptation and 7 days for sampling collection). The animals were fed individually in metabolic cages.
Feces was collected daily, then one tenth of daily feces weight was taken. Feces samples were dried at 60-70°C in a hot air oven. The orts were weighted daily, meanwhile feed intake was calculated. The dried samples of feces and feeds were grinded to pass through 1 mm screen and then these samples of rations and feces were stored for chemical analysis. Consequently, the nutrients digestibility and nutritive values of the experimental rations were calculated.
Sampling and analytical procedures
Chemical analysis: Feeds and feces were analyzed for proximate analyses and gross energy according to AOAC (2000). Nitrogen free extract was calculated by difference method. Fiber fractions were analyzed according to Van Soest et al. (1991).
Rumen liquor sampling: Rumen liquor samples were taken just before morning feeding, then after at three and six hours post feeding. Rumen liquor samples were collected through rubber stomach tube attached to electric suction pump. Samples of rumen liquor were strained through two layers of cheesecloth and its pH was immediately measured by Beckman pH meters. Strained Rumen Liquor (SRL) samples were acidified with 0.1 N hydrochloric acid and concentrated orthophosphoric acid and stored by freezing for determination of total volatile fatty acids (TVFA’s). Concentration of ammonia-N in rumen liquor was determined according to Conway (1957). The concentration of total VFA’s was determined in rumen liquor by steam distillation method (Warner, 1964) using Mrkham micro distillation apparatus.
Blood parameters: At the end of growth trial, blood samples were withdrawn from all the experimental animals. The blood samples were taken from jugular vein into dry clean glass tubes using heparin as anticoagulant and then centrifuged for 15 min at 4000 rpm to obtain plasma. Blood plasma constituents were determined using commercial kits. The total protein and creatinine as described by Tietz (1986, 1990), albumin was determined according to Doumas et al. (1971), blood plasma urea was determined according to Patton and Crouch (1977). Alanine transaminase (ALT) and activity of aspartate transaminase (AST) were determined by the methods of Young (1997).
Statistical analysis: Data was analyzed using the general liner model procedure of SAS (2000). One way ANOVA procedure was used to analyze data following the next model:
Yi = μ + Ti+Ei
were, μ is the overall mean of Yi, Ti is the treatment effect; Ei is the experimental error. The differences among means were separated according to Duncan New Multiple Range Test (Duncan, 1955).
RESULTS AND DISCUSSION
Nutrients digestibility and nutritive values: Data concerning nutrients digestibilities and nutritive values Table 2, showed that yeast supplementation either inactivated (T2) or dried (T3) increase the digestibilities of all dietary nutrients beside the NDF and cellulose significantly compared with the control.
The increase in the population and/or activity of rumen cellulolytic bacteria and ciliate protozoa number which represent more than 90% of rumen fibrolysis activity (Kamel et al., 2004; Tripathi and Karim, 2011) by providing rumen microflora with vitamins or other growth factors or by scavage oxygen entered in rumen (Chaucheyras-Durand et al., 2008) may explain the increase in CF digestion when ration was supplemented with yeast. Also, the increase in CP digestibility with yeast supplementation may have been due to an increase in proleolytic bacteria counts (Tripathi and Karim, 2011). In the same trend, El-Ashry et al. (2001), Haddad and Goussous (2005) and Kholif and Khorshed (2006) recorded increases in OM, CF and CP digestibilities with yeast supplementation.
Meanwhile, inactivated yeast (T2) was significantly (p<0.05) highest in digestion of ADF and hemicellulose, while dried yeast (T3) had the highest cellulose digestibility compared with those fed control (T1).
Regarding the nutritive values, there were significant differences (p<0.05) in total digestible nutrients (TDN) values being T2 (73.30%) the highest followed by T3 (68.05%) and T1 (62.83%). This could be attributed to high digestibilities of CP, EE, CF and NFE for both rations supplemented with yeast (T2 and T3). On the other hand, no significant differences (p<0.05) in digestible crude protein (DCP) was detected with yeast supplementation.
Rumen liquor parameters: Although yeast supplementation had no significant effect on rumen pH (Table 3), it tended to be higher with lambs fed ration supplemented with inactivated yeast (T2). Average rumen pH ranged from 6.25-6.55.
| Table 2: | Effect of yeast supplementation on nutrients digestibility and nutritive values of the experimental rations |
| a,bMeans in the same row with different superscript are significantly different (p<0.05), T1: Control ration (Concentrate feed mixture + Clover hay), T2: Control ration supplemented with 5 g h-1 day-1 inactivated yeast (Thepax®), T3: Control ration supplemented with 5 g h-1 day-1 dried yeast (Yeastmax®), DM: Dry matter, OM: Organic mater, CP: Crude protein, EE: Ether extract, CF: Crude fiber, NFE: Nitrogen free extract, NDF: Neutral detergent fiber, ADF: Acid detergent fiber and ADL: Acid detergent lignin | |
| Table 3: | Effect of yeast supplementation on rumen parameters of growing lambs |
| a,bMeans in the same row with different superscript are significantly different (p<0.05), T1: Control ration (Concentrate feed mixture + Clover hay), T2: Control ration supplemented with 5 g h-1 day-1 inactivated yeast (Thepax®) and T3: Control ration supplemented with 5 g h-1 day-1 dried yeast (Yeastmax®) | |
These values are higher than the critical level to be considered rumen acidosis or to affect the microbial diversity in rumen (Tripathi and Karim, 2011).
The insignificant effect of yeast supplementation on rumen pH might be attributed to high roughage intake by animals which acted as a buffer (Al-Dabeeb and Ahmed, 2002). This result is parallel with those obtained by Kawas et al. (2007) and Oeztuerk (2009). On the other hand, a pH stabilization effect was reported either when sheep received active yeast during their adaptation to a high-concentrate diet (Fonty and Chaucheyras-Durand, 2006).
The rumen ammonia values were insignificantly decreased either with inactivated yeast (T2) or dried yeast (T3) compared to control being 52.47, 47.20 and 53.67 mg/100 mL rumen liquor, in the same order. The decrease in rumen ammonia N with yeast supplementation is in agreement with results obtained by Newbold et al. (1996). The reduced concentrations of ammonia N in rumen appear to be a result of increased incorporation of ammonia into microbial protein and may be the direct result of stimulated microbial activity. However, Oeztuerk (2009) recorded an increase in rumen NH3-N concentration with yeast supplementation.
Rumen TVFA concentration was significantly (p<0.05) higher with yeast supplementation (T2 and T3) being 16.03 and 16.17 mL eq/100 mL rumen liquor , respectively compared to control (12.43 mL eq). Al-Dabeeb and Ahmed (2002) observed similar effects when added yeast culture either to high-roughage or high-concentrate rations. On the other hand, Kawas et al. (2007) found that yeast supplementation had no significant effects on rumen TVFA concentration. However, Tripathi and Karim (2011) noticed a decrease in TVFA concentration. The differences between this study and other studies could be attributed to differences in quantities used and/or different strains of yeast as suggested before (Al-Dabeeb and Ahmed, 2002).
Blood parameters: Data in Table 4 showed that no significant differences among treatments in blood parameters, except total protein and urea concentrations which were high with animals fed inactivated yeast (T2) than T3 and T1.
| Table 4: | Effect of yeast supplementation on blood parameters of growing lambs |
| a,bMeans in the same row with different superscript are significantly different (p<0.05), T1: Control ration (Concentrate feed mixture + Clover hay), T2: Control ration supplemented with 5 g h-1 day-1 inactivated yeast (Thepax®) and T3: Control ration supplemented with 5 g h-1 day-1 dried yeast (Yeastmax®), 1Aspartate aminotransferase and 2Alanine transaminase | |
These results may be due to the improvement in metabolic process as a result of yeast supplementation (Kholif and Khorshed, 2006).
The insignificant increase in glucose concentration with yeast supplementation may be due to the increase in total DM intake and digestibility of most nutrients. Not only concentration of glucose in blood is influenced by energy consumption resulting in greater glucose abosorption but also, by utilization by tissues (Magalhaes et al., 2008). Also, Abo El-Nor and Kholif (1998) reported higher blood glucose concentration in cows fed diets containing yeast. This increase in glucose concentration in the yeast supplemented group might be related to a temperate improvement in gluconeogenesis and increased lactose absorption (De Valdez et al., 1997). While, Beauchemin et al. (2003) did not observe any changes in glucose concentration with yeast supplementation.
The results concerning both AST and ALT concentration indicated that yeast supplementation to sheep ration had no adverse effect on animal health. These results are in accordance with El-Ashry et al. (2001) and Kholif and Khorshed (2006).
Growth performance: Results in Table 5 showed that total body weight gain and average daily gain of lambs fed inactivated yeast (T2) were significantly (p<0.05) higher being 17.58 kg and 195.33 g than those fed dried yeast (T3) being 17.22 kg and 191.33 g or those fed control (T1) being 15.62 kg and 173.56 g, in the same order. These results could be attributed to the increase in digestibilities of most nutrients and nutritive values as TDN and DCP with yeast supplementation. Present findings are in consistent with the findings of Haddad and Goussous (2005) and Tripathi and Karim (2011). While, no significant change in average daily gain was observed with yeast addition by Beauchemin et al. (2003), Kawas et al. (2007), Magalhaes et al. (2008) and Titi et al. (2008).
A significant (p<0.05) increase in daily total dry matter intake was recorded for T3 (1.13 kg day-1). While, T2 was similar to control being 1.06 kg day-1 for both groups. The same notice could be observed with both TDN and DCP intakes. Beauchemin et al. (2003), Kawas et al. (2007), Titi et al. (2008) and Tripathi and Karim (2010, 2011) did not find a significant effect of yeast supplementation on dry matter intake. It is established that dry matter intake may be improved when yeast culture is added to low protein rations, while intake remains unaffected or reduced with high protein rations (Ando et al., 2004; Castillo et al., 2006).
| Table 5: | Effect of yeast supplementation on growth performance of growing lambs |
| a,bMeans in the same row with different superscript are significantly different (p<0.05), T1: Control ration (Concentrate feed mixture + Clover hay), T2: Control ration supplemented with 5 g h-1 day-1 inactivated yeast (Thepax®) and T3: Control ration supplemented with 5 g h-1 day-1 dried yeast (Yeastmax®), *Average daily gain: Total gain, g/90 days | |
The feed conversion ratio indicated that supplementation with inactivated yeast (T2) was improved by 10.29%. Haddad and Goussous (2005), Kawas et al. (2007) and Tripathi and Karim (2010) recorded an improvement in feed conversion efficiency with yeast supplementation. While, no change was observed by Magalhaes et al. (2008) and Titi et al. (2008).
CONCLUSION
Supplementation with two yeast products (inactivated or dried) by 5 g h-1 day-1 increased digestibilities of most nutrients, nutritive value as TDN and DCP, average daily gain and improved feed conversion efficiency but did not affect rumen pH and ammonia N. Blood parameters indicated that yeast supplementation to sheep ration had no adverse effect on animal health. Supplementation with inactivated yeast had the potential to improve digestibilities and growth and can be effectively used as growth promoters.