Performance of broiler chicken on low protein diet supplemented with protease enzyme

Introduction

Endogenous proteases is synthesized and released in the GI tract and these proteases are accounted to be sufficient to optimize feed protein utilization (Nir et al., 1993) [20] . Despite of that, exogenous protease is effective in low protein diets. Exogenous serine protease enzymes enhancing protein and energy digestibility and thus improve the performance parameters. The increase nutrient availability with enzyme supplementation is associated with improved digestibility or retention of energy, protein or other nutrients. Chick consuming soybean meal diet supplemented with protease had higher body weight gain, apparent nitrogen retention and apparent metabolizable energy without affecting FCR (Ghazi et al., 1997) [13] . Hence experiment was carried to study the performance of broilers on low protein diet with and without protease.

Materials and Methods

One hundred and eighty commercial broilers, divided into six groups were fed for 6 weeks. The T1 group was fed as per BIS (2007) [2] . The T2 was fed on diet with 5 percent reduction in protein than T1, T3 with 10 percent reduction in protein than T1, T4 standard diet with protease, T5 with 5 percent reduced protein than T1 with protease and T6 with 10 percent reduced protein than T1 with protease. The body weight of each bird was recorded weekly, and feed consumption daily. A metabolic trial of 5 days collection period was conducted for five consecutive days during 6 th week of experiment. The feed ingredients, mash feed and samples collected during the metabolic trial were analyzed as per AOAC (2005) [1] . The samples collected during 6 th week of experiment were analyzed for total protein, albumin and globulin (Doumas, 1978) [3] . The carcass studies were conducted at the end of experiment. The data was analyzed statistically as per Snedecor and Cochran (1994) [4] . (The 1 gm of protease equals 6,00,000 IU and protease was supplemented @ 100 g/ton of feed). The BW gain (Table 2) were significantly (p<0.01) higher in T2 and at par with T4 group. Addition of protease enzyme enhances body weights, however effect of protease could not be seen in 10 percent protein reduced group. The findings corroborates with Rada et al., (2013) [21] , reported higher body weights on low protein feed. Ardekani and Chamani (2012) [8] also reported more body weights in broilers when protein level was reduced. Kamran et al., (2004) [16] reported beneficial effects on body weights when protein in diet was reduced. However Angel et al., (2011) [7] and Frietas et al., (2011) [12] reported no significant effect on growth of birds, fed low CP feed with protease. The feed consumption was more in T2 and T3 groups and corroborates with Yadav and Sah (2005) [23] who reported increased feed consumption of broilers on low protein diet. The increase in feed consumption of birds due to reduced protein may be attributed to the tendency of the birds to eat more in order to compensate for lower protein diets. The less feed consumption due to reduced protein may be due to the protease, which also increased CP metabolizability, as evident in the present study. Improvement in feed consumption of control group with protease are in agreement with Khan et al., (2006) [18] who observed increased feed consumption due to enzyme. The better FCR was observed in T2 and T4 group, indicated better conversion of feed into body weight on low protein feed. Addition of protease in low protein diet could not be effective in conversion of feed into meat. The findings are consistent with Kamran et al., (2004) [16] and Freitas et al., (2011) [12] reporting better FCR on protease in control diet. However Rada et al., (2013) [21] observed no significant change due to low protein diet. The DM metabolizability was higher in T6 group and corroborates with Olukosi et al., (2007) [24] reported higher (p<0.05) DM digestibility when enzyme alone was added in the feed. Khan et al., (2006) [18] also reported increased (p<0.05) DM digestibility due to enzyme addition. Zanella et al., (1999) [25] , observed increased starch digestibility due to enzyme supplementation, attributed to solubilization and disruption of grains endosperm cell walls. The effect of protease could not be seen in normal diet in improving CP metabolizability rather it worked better on CP reduced diet and exceptionally well, indicated best utilization of protein when fed at lower level. These results are supported by Angel et al., (2011) [7] and Yadav and Sah (2005) [23] . The CF metabolizability was better in group receiving 10 percent low protein diet and in agreement with Yadav and Sah (2005) [23] . Effects of protease on poultry diet do not appear to be completely limited to protein digestion, but also affect the digestibility of other nutrients. Increased digestion of corn starch with the use of protease, attributed to the disruption of protein matrix in starch granules. The protein hydrolysis catalyzed by the exogenous protease may be responsible for the improvement in apparent CP digestibility. The fibre degradation may be one of the mechanisms by which protease increases the digestion of nutrients in chickens. The serum total protein was significantly higher in T1 and T4 group over the protein deficient diet. The findings are supported by Abudabos (2012) [6] who observed higher serum total protein due to enzyme. However, El-Katcha et al., (2014) [11] reported no significant effect on blood serum total protein. The serum albumin and globulin levels were also higher on control diet with enzyme exhibited positive effect of protease on serum biochemical parameters in normal diet. These findings are in consistent with Hernandez et al., (2012) [8] . The serum protein, albumin and globulin on protein deficient diet either with protease or without protease supplementation were within the normal range as reported by Jerry et al. (2008) [26] . The dressing percentage was higher in both the groups i.e. with and without enzyme supplementation than control and consistent with Kamran et al., (2004) [16] . The improvement in carcass yield with the use of low CP diet (supplemented with essential amino acids) could be due to reduced heat increment, which is associated with the metabolism of excess protein (Kamran et al., 2004) [16] . The breast meat was less on 10 percent low protein diet with and without enzyme and it was comparable in either group of control diet. These results are supported by Cafe et al., (2002) [9] reporting no consistent effect on yield of breast. The net profit Rs. per kg BW was highest in T1 (Rs.10.01) and supported by Kamran et al., (2004) [16] and Kamran et al., (2011) [17] . It was concluded that the protein level can be reduced in broiler diet upto five percent than standard without any adverse effect on birds for economical broiler production.

References

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