Introduction

The biggest single expense in any system of poultry production is feed accounting for up to 70% of total production cost. The majority of Indian broiler diets are composed of about 70% maize, 20% soybean meal or other similar protein sources and 10% micro-ingredients, additives and supplements. In the broiler sector, the net profit is usually 10-15%. Hence, even a small saving in feed cost, without sacrificing the performance of the broilers will bring significant improvement in the profitability. Improving digestibility of the nutrients is the most obvious and easiest way to improve the ‘net benefit’ that the broiler obtains from its feed. Thus, the best way to achieve this goal is the use of enzymes that can be added in the broiler feed.

The benefits of using enzymes in poultry diets include not only improved bird performance and feed conversion but also less environmental problems due to reduced output of excreta (Khattak et al., 2006). Feed enzymes are used to improve the digestibility of feed ingredients and reduce the detrimental effects of anti-nutritional factors. As the concept of cocktail enzymes has got limitations, using specific enzyme singly to target specific substrate to release the nutrients has been developed. For proteins, the digestibility can be increased by exogenous proteases by mimicking the action of endogenous proteases. Protease improves protein digestibility around 2-5% depending on the type of ingredients used. Hence, depending upon the need, specific group of proteases can be produced and used for specific substrates. In addition, protease offers other benefits like it reduces nitrogen excretion to the environment, it reduces nitrogen load in the gastrointestinal tract, which in turn can reduce the amount of substrate available to potentially pathogenic bacteria and thus improves feed utilization.

However, in India, the use of protease in the broiler diet is not yet common due to its inconsistent results in the corn soybean based diets. Sunflower extraction is a poor quality protein source available under Indian conditions and it is relatively cheaper as compared to soybean meal. Hence, if the digestibility of protein from sunflower meal could be improved by using proteases, it can be the promising substitute to replace expensive soybean meal. Thus, a study has been designed to evaluate the effect of protease in broilers fed with diets by using sunflower meal at different levels.

Materials and Methods

The trial was conducted on 480 broilers of Cobb 400 strain for the period of five weeks. The day-old chicks were divided into eight groups of 60 chicks each. The groups were further divided into six replicates of 10 chicks each. Each group was subjected to one of the following treatments-

Group A : Control – Corn-soybean diet

Group B : Corn-soy diet + Protease*

Group C : Sunflower meal replacing soybean meal protein at 5% level

Group D : Sunflower meal replacing soybean meal protein at 5% level + Protease*

Group E : Sunflower meal replacing soybean meal protein at 10% level

Group F : Sunflower meal replacing soybean meal protein at 10% level + Protease*

Group G : Sunflower meal replacing soybean meal protein at 15% level

Group H : Sunflower meal replacing soybean meal protein at 15% level + Protease*

* Protease enzyme with protease activity 75,000 PROT/ g was used @ 200 g/ T of feed.

All the diets were isocaloric and isonitrogenous. The daily records for feed consumption and mortality were maintained. Weekly records of live weight, gain in weight, feed consumption, feed conversion ratio, and mortality were maintained.  The economics of the production was calculated at the end of the trial.

The feed formulations of the diets used in the trial are presented in Tables 1, 2 and 3.

Table 1: Feed formulation of the prestarter diets

Table 2: Feed formulation of the starter diets

Table 3: Feed formulation of the finisher diets

Statistical Methods

The data collected pertaining to all the parameters were subjected to completely randomized block design as per Snedecor and Cochran (1994).

Results and Discussion

Live Weight

The live body weights of the birds from the groups A to H at the end of five weeks were 1804.46, 1879.17, 1919.45, 1882.48, 1913.59, 1900.60, 1919.92, and 1882.47 g, respectively. The birds from group G receiving diet with sunflower meal replacing soybean meal protein at 15% level recorded the highest live weight at the end of the five weeks followed by the birds from the groups C and E receiving diet with sunflower meal replacing soybean meal protein at 5% and 10% levels, respectively. The birds receiving sunflower meal protein replacing soybean meal protein at 5, 10 and 15% levels recorded 6.37, 6.05 and 6.40% higher live weights at the end of five weeks than control group, respectively. Further, it is evident that, as the level of the sunflower meal protein was increased in the diet, the average weekly live weights of the birds also increased. It is observed that the birds receiving control diet with protease supplementation recorded 4.14% higher live weights than the birds from its non-supplemented counterpart group A. However, among the groups receiving sunflower meal replacing soybean meal protein at 5, 10 and 15% levels, the birds from groups receiving diets with protease supplementation did not record higher live weights than their non-supplemented counterparts. The statistical analysis revealed that, the differences in the weekly live weights of the birds from different groups were statistically non-significant. Wang et al. (2006) found that supplementation of Versazyme, keratinase-based enzyme helped the broilers in recording significantly higher live body weighs. Rada et al. (2013) recorded marginal improvement in the body weights of broilers due to supplementation of protease. Yan et al. (2014) recorded that protease increased body weights significantly on 35 days (P =0.049) and numerically on 42 days (P= 0.060). Similar results were noted in the present trial.

Hence, it was concluded that the sunflower meal replacing soybean meal protein upto 15% level helps the birds for recoding higher live weights. The supplementation of protease to the birds receiving corn soybean based diet helps to get higher live body weights. However, the supplementation of protease does not give any beneficial effect on live body weights when the diets with sunflower meal replacing soybean meal protein upto 15% levels were given to the birds.

Gain in Weight

The total gain in weights of birds from the groups A to H at the end of five weeks were 1760.06, 1834.25, 1874.85, 1937.85, 1868.24, 1855.74, 1875.50 and 1837.76 g, respectively. The corresponding average weekly gain in weights of birds from groups A to H was 352.01, 366.85, 374.97, 387.51, 373.65, 371.15, 375.10 and 367.55 g. The birds from group D receiving the diet with sunflower meal replacing soybean meal protein at 5% level supplemented with protease enzyme recorded the highest gain in weight at the end of the five weeks followed by the birds from the groups G and C receiving diet with sunflower meal replacing soybean meal protein at 15% and 5% levels, respectively. It is revealed that the birds receiving sunflower meal protein replacing soybean meal protein at 5, 10 and 15% levels recorded 6.52., 6.15 and 6.56% higher gain in weights at the end of five weeks than the birds from control group, respectively. Further, it is evident that, as the level of the sunflower meal protein was increased in the diet, the average weekly gain in weights of birds also increased.

It is observed that the birds from group B receiving control diet with protease supplementation recorded 4.22% higher gain in weights than the birds from non-supplemented counterpart group A. Similarly, the birds from group D receiving diet with sunflower meal replacing soybean meal at 5% level with protease supplementation recorded 3.34% higher gain in weights than the birds from non-supplemented counterpart. However, the birds from group F and H receiving diets with sunflower meal replacing soybean meal at 10 & 15% levels along with protease supplementation, respectively, recorded lower gain in weights than the birds from their respective non-supplemented counterparts. The statistical analysis revealed that, the differences among the gain in weight of the birds from different groups were statistically non-significant. Angel et al. (2011) had reported that supplementation of protease compensated the reduction in body weight gain due to reduction in crude protein levels in the broiler diets.  Similar results were observed in this experiment.

Hence, it was concluded that the sunflower meal replacing soybean meal protein upto 15% level helps the birds for recoding higher gain in weights. The supplementation of protease to the birds receiving corn soybean based diet helped to get higher gain in weights. Moreover, the supplementation of protease also helped the birds to gain higher weights when the diet with sunflower meal replacing soybean meal at 5% level is given to the birds. However, the supplementation of protease does not give any beneficial effect on gain in weights when the diets with sunflower meal replacing soybean meal at 10 and 15% levels are given to the birds.

Feed Consumption

The total feed consumption of birds from the groups A to H at the end of five weeks were 3155.01, 3111.06, 3416.10, 3347.23, 3428,60, 3364.35, 3494.48 and 3241.18 g, respectively. The birds from group G receiving the diet with sunflower meal replacing soybean meal protein at 15% level recorded the highest feed consumption at the end of the five weeks followed by the birds from the groups E and C receiving diet with sunflower meal replacing soybean meal protein at 10% and 5% levels, respectively. It is revealed that the birds receiving sunflower meal protein replacing soybean meal protein at 5, 10 and 15% levels recorded 8.28, 8.67 and 10.76% higher feed consumption at the end of five weeks than the birds from control group, respectively. Further, it is evident that as the level of the sunflower meal protein was increased in the diet, the feed consumption of the birds also increased. It is observed that the birds from group B receiving control diet with protease supplementation recorded 1.39% lower feed consumption than the birds from non-supplemented counterpart group A. Similarly, the birds from groups D, F and H receiving diet with sunflower meal replacing soybean meal at 5, 10 and 15% levels, respectively, along with protease supplementation recorded 2.02, 1.87 and 7.25% lower feed consumption than the birds from their respective non-supplemented counterpart groups C, E and G. Thus, enzyme supplementation in general helped the birds to record lower feed consumption. The statistical analysis revealed that, the differences among the feed consumption of the birds from different groups were statistically non-significant. Angel et al. (2011) reported that supplementation of protease had no significant effect on the feed consumption of the broilers. Similar findings were observed in the present study.

Hence, it was concluded that as the level of the sunflower meal replacing soybean meal protein increases from 5 to 15%, the feed consumption of the birds increase. The supplementation of protease to the birds receiving corn soybean based diet as well as the diets with 5, 10 and 15% sunflower meal replacing soybean meal helped to reduce the feed consumption of the birds.

Feed Conversion Ratio

The average weekly feed conversion ratios recorded by the birds from groups A to H at the end of five weeks were 1.71, 1.62, 1.72, 1.66, 1.73, 1.71, 1.75 and 1.67, respectively. The corresponding cumulative feed conversion ratios recorded by the birds from groups A to H were 1.79, 1.70, 1.82, 1.82, 1.83, 1.81, 1.86 and 1.76. It is noted that the birds from group G receiving the diet with sunflower meal replacing soybean meal protein at 15% level recorded the poorest average weekly feed conversion ratio followed by the birds from the groups E and C receiving diet with sunflower meal replacing soybean meal protein at 10% and 5% levels, respectively. The birds from the group B receiving corn-soybean based diet supplemented with protease enzyme recorded better feed conversion ratio among all the treatment groups including control. It is revealed that the birds receiving sunflower meal protein replacing soybean meal protein at 5, 10 and 15% levels recorded 0.58, 1.16 and 2.34% poorer feed conversion ratio than the birds from control group, respectively. Further, it is evident that as the level of the sunflower meal protein was increased in the diet, the feed conversion ratio of the birds was deteriorated. It is observed that the birds from group B receiving control diet with protease supplementation recorded 5.26% better feed conversion ratio than the birds from non-supplemented counterpart group A. Similarly, the birds from groups D, F and H receiving diet with sunflower meal replacing soybean meal at 5, 10 and 15% levels, respectively, along with protease supplementation recorded 3.49, 1.16 and 4.57% better feed conversion ratio from their respective non-supplemented counterpart groups C, E and G. The statistical analysis revealed that, the differences among the feed conversion ration recorded by the birds from different groups were statistically non-significant.

Wang et al. (2006) found that supplementation of Versazyme, keratinase-based enzyme helped the broilers in recording significantly better FCR. Angel et al. (2011) had reported that supplementation of protease compensated the ill effect on the FCR due to reduction in crude protein levels in the broiler diets. Rada et al. (2013) recorded marginal improvement in FCR of the broilers due to supplementation of protease. Yan et al. (2014) recorded that protease significantly improved FCR of the birds fed diets containing low or high protein on 35 and 42 days. Similar results are observed in the present experiment.

Hence, it was concluded that as the level of the sunflower meal replacing soybean meal protein increases from 5 to 15%, the feed conversion ratio of the birds deteriorated. The supplementation of protease to the birds receiving corn soybean based diet as well as the diets with 5, 10 and 15% sunflower meal replacing soybean meal helped to record better feed conversion ratio by the birds.

Mortality

It was noted that the mortality of birds form different groups was well within the limit and hence it was concluded that the use of sunflower meal replacing soybean meal protein upto 15% level and the supplementation of protease did not have any ill effect on the health of the birds.

Economics of Production

The economics of production was calculated at the end of the trial period by considering feed cost as the only variable. The cost of production per bird of the broilers form groups A to H were Rs. 138.34, 138.00, 145.95, 144.92, 145.83, 144.96, 147.45 and 140.83, respectively. The profit calculated per bird for the groups A to H were Rs. 6.01, 12.34, 7.61, 5.68, 7.26, 7.09, 6.14 and 9.77, respectively. The corresponding profit per kg of live weight recorded by the birds from groups A to H were Rs. 3.33, 6.57, 3.96, 3.02, 3.79, 3.73, 3.20 and 5.19. It is observed from the table that the birds from the groups C and E receiving sunflower meal replacing soybean meal protein at levels of 5 and 10%, respectively, recorded better profit per kg live weight as compared to control group A. However, the birds from the group G receiving 15% sunflower meal replacing soybean meal protein recorded lower profit margin as compared to the birds from groups C and E as well as control. It is also revealed that the birds from groups B and H receiving protease supplementation recorded comparatively higher profits than the birds from their respective non-enzyme supplemented counterpart groups A and G, respectively. However, the birds from the groups D and F supplemented with protease recorded lower profits as compared to their respective non-enzyme supplemented counterpart groups C and E, respectively.

Hence, it can be concluded that the inclusion of sunflower meal replacing soybean meal protein at 5 and 10% levels helped to generate marginally higher profits. Moreover, the supplementation of protease is found to record comparatively higher profit margins from the birds receiving corn- soybean diet and the diet with 15% sunflower meal replacing soybean meal protein.         

Overall Performance

From Table 4 it is noted that the supplementation of protease enzyme helped the birds in recording better live weight, feed conversion ratio and considerably higher profit margins when the birds were fed with the corn-soybean based diet. It is also noticed that the birds receiving diets with the replacement of soybean meal protein with sunflower meal protein at 5 and 10% levels, when supplemented with protease enzyme did not give any beneficial effect in terms of production performance as well as profits. However, the birds receiving the diet with replacement of soybean meal protein with sunflower meal protein at 15% level, when supplemented with protease enzyme recorded better feed conversion ratio and higher profit margins as compared to its non-supplemented counterpart.

Conclusion

It can be concluded that the supplementation of protease enzyme with protease activity of 75,000 PROT/ g in feed @ 200 g/ T is helpful for recording better production performance and higher profit margins in broilers receiving the corn soybean based diets and diet with replacement of soybean meal protein with sunflower meal protein at 15% level.

Acknowledgements

DSM Nutritional Products

References

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