Dietary effect of autolysed yeast on broilers ( Levabon ® , Biomin Austria ) on broiler growth

A pilot scale project of 4 weeks feeding trial using 1500 broiler chicks was conducted in a commercial poultry shed, hired for this purpose to study the comparative growth performance of a flock raised on levabon supplemented feed to that raised on the same feed without levabon (control). A total 1500 broiler chicks were divided in to 3 groups, control and treated (1g/kg and 1.5g/kg). Each group was further divided in to 10 replicates, containing 50 birds per replicate. Feed intake was not influenced by supplementation of levabon during this experiment (p>0.005), however slightly higher numerical values were observed in treated group. While overall weight gain and feed conversion ratio was significantly Higher (p>0.05) in birds fed on Levabon supplemented feed (1.5g/kg) as compared to the control group (feed without levabon). Dressing percentage, giblet weight was not significantly influenced by dietary treatment of Levabon (autolysed yeast), mortality was significantly reduced by supplementation of levabon (p>0.05) during this trail. The net income per bird was significantly higher in treatment group than control. This study suggests the inclusion of autolysed yeast in broiler diet for getting better performance of broiler chicken.


Introduction
Broilers because of their genetic make-up have rapid growth rate and better feed conversion ratio and their potential cannot be perfectly expressed unless, they are provided with balanced rations and the optimum conditions in the GIT to promote digestion and absorption of nutrients [1].Such balance rations contain protein enriched ingredients resulting in high risk of pathogenic microbe's manifestation.Different feed companies add antibiotics in poultry feed to check the growth of pathogenic microbes and to increase growth performance of broilers.But it is strictly prohibited by European Union since 2006 [2].In order to address this problem, many other feed additive such as prebiotics and pro-biotics are used alternative to antibiotics (World Health Organization, cited by [3].One of the alternatives of antimicromicial as feed additive is yeast (Saccharomyces cerevisiae), which is enriched in high biological valued crude protein up to 40-45% and B-complex vitamins [4].Keeping in the importance of yeast, in this study the effect of autolysed yeast (Levabon®, Biomin Austria) was evaluated on growth performance of broiler's chicks.

Materials and methods
A pilot scale 4 weeks feeding trial using1500 broiler chicks was conducted in a commercial poultry shed, hired for this purpose to study the comparative growth performance of a flock raised on Levabon supplemented feed to that raised on the same feed without Levabon (control).A total 1500 broiler chicks were divided in to 3 groups, control and treated (1g/kg and 1.5g/kg).Each group was further divided in to 10 replicates, containing 50 birds per replicate.Lavabon was supplemented at rate of1g/kg and 1.5g/kg, treatment were assigned randomly.The months of June and July were purposely selected for the experiment in order to test the feed during the most inclement part of the year.Feed and water were provided adlibitum, except for the hot mid day time, when feed was removed.Vaccination was done according to the recommended schedule.Feed intake, weight gain, feed conversion ratio, percent mortality, dressed weight and giblet weight of broiler chicks were used as criteria of response.
Data on chick weight, weight gain and feed consumption was recorded on weekly basis.At the end of experiment representative samples were taken from each group for determining dressing percentage and giblet weight.Levabon supplemented ingredients are listed in (Table 1).

Results and discussion
FEED intake/ Weight gain and feed conversion ratio (FCR): Feed intake was not influenced by supplementation of Levabon during this experiment (P>0.005),however slightly higher numerical values were observed in treated group, but palatability of treated diets may not be a major concern, as poultry have only rudimentary taste buds and so taste and smell are not likely to be of major importance in describing results of diet treatments.In the present study overall weight gain and feed conversion ratio was significantly higher (P>0.05) in birds fed on Levabon supplemented feed (1.5g/kg) as compared to the control group (feed without Levabon).The higher weight gain in treated group may be due to beneficial effects of yeast (Saccharomyes cerevisiae), which is enriched in high valued crude protein up to 40-45% and B-complex vitamins [4].It also contains mannano-oligosaccharieds (MOS), which are helpful in promoting growth performance of broilers, because its exerts some optimistic effects on mucosa of the intestine.Some studies suggest that improved performance of bird may be related with maintenance of balanced normal micro-biota of gastro intestinal tract by competition and antagonism with pathogenic organism; improve metabolism by enhancing the activity of some enzyme in digestion, illeal mucosa development and limiting the action of bacterial enzyme and ammonia gas production; it also stimulate the immune response of body [5].Moreover, it enhance villus cells action, amplify anaerobic and cellulytic bacteria which improve lactate utilization.It has positive effect on gut ph, thus improving the digestibility and growth performance.So these factors might have been responsible for the increase gain in body weight and good feed conversion ratio (FCR).Our results are in line with [6] reported that an improvement broilers performance supplemented with yeast in ration.This also agrees with [7] who reported broiler chicks fed on yeast supplemented diets had shown significant (P<0.05)incensement in live weight gains and feed conversion ratio.Details are given in (Table  2) (p>0.05).This may be due to balanced microbial population in the gastrointestinal tract which has positive effect on physical condition and performance in the broiler chicks.Some studies suggested that it exert some anti-inflammatory effects, which activate natural killer cells and B lymphocytes.MOS has shown some tremendous effects in decreasing pathogenic microbes of the gastro intestinal tract, motivating a strong immune response in body and uplifting the vigor of the intestinal villus [9-11].All the above factors might explain, why lowered mortality was observed in group fed on Levabon supplemented feed as compared to the control group (feed without Levabon).Details are presented in (Table 3). .

Table 5 . Feed intake and weight gain
ConclusionFrom the findings of current study, it is concluded that Inclusion of autolysed yeast @ 1.5g/kg of feed (Saccharomyces cerevisiae) in broiler's ration resulted in an improvement in their performance in terms of weight gain and feed conversion ratio.Farmers should be encouraged to include autolysed yeast in the diet for broilers for getting maximum net profit.Authors' contributionsConceived and designed the experiments: M Ullah, GM Marri & Q Jogi, Performed the experiments: RR Kaleri, H Rizwana, M Rasheed & JP Goil, Analyzed the data: ZA Khoseo, D Kumar & A Sahab, Contributed materials/ analysis/ tools: S Dari & A Kabir, Wrote the paper: RR Kaleri.