Livestock Research for Rural Development 29 (12) 2017 Guide for preparation of papers LRRD Newsletter

Citation of this paper

The utilization of feather meal to increase duck production, carcass quality and feathers growth of local Bali ducks

A Pertiwi, E Widodo, M Nur Ikhsan and B Sundu1

Animal Husbandry Faculty, University of Brawijaya, Malang, Indonesia
b_sundu@untad.ac.id
1 Animal Husbandry Department, University of Tadulako, Palu, Indonesia

Abstract

Raw feather waste has been an environmental problem as the production of feather has been increasing from year to year due to increased population of poultry. Since feather meal is considered to be a low quality feedstuff, hydrothermal processing with enzymatic treatment is one of the ways to improve its quality Two studies were conducted to determine the effects of enzymatically hydrolyzed feather meal (EFM) on feed intake, body weight gain, feed conversion ratio (FCR), carcass weight and carcass percentage (Experiment 1), feather percentage and total number of pinfeathers (Experiment 2). In experiment 1, a total of 108 day-old local Bali ducks were used and placed in the pens and the same number of ducks was used in the experiment 2. The ducks were kept for 10 weeks and fed the experimental diets. The experimental diets were the same in both experiments; CTL: control basal diet, EFM01: basal diet + treated feather meal with 0.01% enzyme (Allzyme FD) and EFM02: basal diet + treated feather meal with 0.02% enzyme. Parameters measured were feed intake, protein intake, body weight gain, feed conversion ratio and carcass percentage in experiment 1 and feather percentage and number of pinfeathers in experiment 2. A completely randomized design was used with 3 different treatment diets and 6 replicate cages in both experiments. Any significance found in the analysis of variance was further tested by Tukey Test.

Results indicated that the supplementation of the diets with enzymatically hydrolyzed feather meal (EFM01 and EFM02) improved feed intake, protein intake, body weight gain, feed conversion ratio and carcass percentage. Ducks fed EFM02 had better body weight gain and FCR than those of ducks fed the EFM01. In experiment 2, ducks fed the enzymatically hydrolyzed feather meal had more and heavier feather production at weeks 7 and 8, but less numbers of protruding pinfeathers and non-protruding pinfeathers than those ducks fed the control basal diet.

In conclusion, the supplementation of the diets with enzymatically hydrolyzed feather meal increased duck performance, carcass percentage and feather percentage and decreased total number of protruding pinfeathers and non-protruding pinfeathers.

Keywords: enzyme, performance, pinfeathers


Introduction

Demands for meat duck in Indonesia have slightly been increasing over the last two decades, from 25,782 ton in 2009 to 36,346 ton in 2015 (Dirjen Peternakan dan Kesehatan Hewan 2015). Supplies of ducks for meat were previously from culled local ducks reared for eggs. Scavenging herding system is still commonly practiced and contributed most of the duck meat in the Indonesia’s market. Since the duck meat business is a rural based and practiced by small holder farmers, the duck meat industry is relatively small in comparison to the broiler industry. The slow growth of duck industry in Indonesia was partly due to low production and carcass quality as Indonesia’s duck industry relies much on local ducks, with commonly having black or dark feather. These particular dark color ducks are commonly found in tropical countries as ducks need to be able to adapt with high intensity of sunlight (Galvan and Solano 2016).

The appearance and quality of carcass can determine preference of consumers. The dark color feather is not preferred by the consumers due to the fact that pinfeathers were still left on the carcass of duck after commercial de-feathering. Mechanical pluckers with revolving tuber finger were usually used to remove most of the feathers. A lot of dark / black feather follicles (pinfeathers) left on the skin (protruding pin feathers) or just below the skin (non-protruding pinfeathers) produced carcasses that look dirty. To have the carcass free from pinfeathers takes much time as these pinfeathers must be removed by hand. There is scarcely practical solution for the removal of pinfeathers unless the ducks were kept much longer up to all the pinfeathers growing longer. However, this solution creates problem of meat toughness of older ducks.

Nutritional approach might be able to cope with the problem of dirty carcass by accelerating the growth of duck feathers, including the pinfeathers. This can be made by providing nutrients matching to the nutrients profile of feathers. The uses of feather meal in poultry diets have been practiced for decades. The uses of this waste product in the diet are not only to supply the nutrients for feather growth but also to minimize environmental pollution of poultry waste material. The problem of poultry waste has been a main concern in Indonesia since Indonesia is one of the largest poultry producer in the world, with a total production of 3,2750.000 tons in 2015 (Dirjen Peternakan dan Kesehatan Hewan 2015). This is equivalent to 32,750 tons feather meal production in 2015 (Rutkowski et al 2003).

Although the protein profiles of feather meal is matching to the feather growth, most of the protein in feather meal (90%) is in the form of keratin, which is categorized by high stability and low solubility due to the presence of Sulphur to Sulphur bound between cysteine amino acids (Brebu and Spiridon 2011). Accordingly, this waste product is regarded a low quality feedstuff. Treatments to improve the quality of feather meal have been done through fermentation (Mulia et al 2016), chemical treatments (Staron et al 2014), Hydro-thermal application (Kormanjos et al 2015) and enzymatic treatment (Rutkowski et al 2003). The aim of these treatments is to disrupt the structure of keratin in feathers to make the protein available to non ruminant animals. Two studies have been carried out to determine the effect of feather meal treated with enzyme on duck performance, carcass percentage and feather growth.


Materials and methods

Production of enzymatically hydrolized feather meal.

The waste of broiler’s feather was collected locally from broiler slaughter house. The wet feathers were gathered and cleaned from any foreign contamination such as blood, feed material and excreta. The feathers were oven-dried for three consecutive days at 60oC. A total of 100 and 200 g enzyme (Allzyme FD) were diluted in 50 ml tap water and sprayed onto the 10 kgs dried feather meal to have 0.01 and 0.02% inclusion of enzyme respectively. During spraying, the feather meal was stirred evenly. The mixtures between enzyme and feather meal were placed into an autoclave previously heated to 60oC for 20 minutes. After 1 hour the temperature was raised at120oC with 2.5 atmospheres. The feather was then oven dried for 3 days at 60oC prior to grinding with hammer mill. Enzymatically hydrolyzed feather meal EHFM was produced and used as a feedstuff.

Ducks and feeds

A total of 108 day-old male Bali ducks were purchased locally and used as experimental animals for growth and carcass study (Experiment 1) and another 108 day-old male Bali ducks were used for feather growth study (Experiment 2). The ducks were allocated in the three brooder cages for 2 weeks based on treatments and then transferred into 18 pens. The animals were kept for 10 weeks.

Experimental design

The experimental diets used in this study were:

CTL: 100% control basal diet

EFM01: 95% basal diet + 5% feather meal treated with 0.01% enzyme (Allzyme FD)

EFM02: 95% basal diet + 5% feather meal treated with 0.02% enzyme (Allzyme FD).

Experimental diets

The experimental diets used in this study are shown in Tables 1 and 2. The nutrient contents of the basal diet were based on NRC (1994). The ducks were allowed to consume the basal and treated diets. Water and feed were supplied at all times throughout the study.

Table 1. Composition of the experimental starter diets (%)

Ingredients

CTL

EFM01

EFM02

Soybean meal

28,0

26.6

26.6

Maize

57,7

54.8

54.8

Fish meal

9.0

8.6

8.6

Rice bran

2.0

1.9

1.9

Copra meal

2.0

1.9

1.9

Palm oil

0.0

0.0

0.0

Dicalcium phosphate

0.10

0.10

0.10

Limestone

0.10

0.10

0.10

Salt

0.2 0

0.19

0.19

Lysine

0.50

0.47

0.47

Vitamin and Mineral Mixture

0.40

0.38

0.38

Enzymatically Hydrolyzed feather meal

0.0

5.0

5.0

Calculated:

Crude protein

22.8

25.7

25.8

Crude fibre

4.9

4.7

4.7

ME (K Cal/kg)

2905

2877

2876

Lysine

1.18

1.24

1.25

Methionine

0.18

1.20

1.21

Calcium

0.77

0.75

0.75

Phosphorus

0.7

0.69

0.69



Table 2. Composition of the experimental grower diets (%)

Ingredients

CTL

EFM01

EFM02

Soybean meal

15.0

14.3

14.3

Maize

53.2

50.5

50.5

Fish meal

7.2

6.8

6.8

Rice bran

3.9

14.4

14.4

Copra meal

5.2

4.9

4.9

Palm oil

2.0

1.9

1.9

Dicalcium phosphate

0.63

0.60

0.60

Limestone

0.53

0.50

0.50

Salt

0.27

0.26

0.26

Lysine

0.30

0.29

0.29

Vitamin and Mineral Mixture

0.47

0.45

0.45

Enzymatically hydrolysed feather meal

0

5.0

5.0

Calculated:



Crude protein

17.0

20.2

20.3

Crude fibre

4.7

4.5

4.5

ME (K Cal/kg)

3002

2969

2970

Lysine

0.84

0.91

0.91

Methionine

0.19

0.21

0.21

Calcium

1.01

0.98

0.98

Phosphorus

0.7

0.69

0.69

Parameters

The parameters measured in Trial 1 were feed intake, dry matter intake, body weight gain, feed conversion ratio, carcass weight and carcass percentage. At the end of the experiment, fifty four ducks (3 birds per replicate cage) were randomly selected for carcass measurements. The ducks were killed by cervical dislocation and dressed by removing the feathers using mechanical plucker. The eviscerated ducks were dressed by removing the neck, the shanks and the internal organs. The dressed ducks (carcasses) after manually removing the pin feathers were weighed and recorded.

In Trial 2, the measurement of feather growth was done at weeks 7, 8, 9 and 10 by slaughtering six ducks (one duck per experimental unit) per week. The parameters were total feather weight, feather percentage, total number of protruding pinfeathers and non-protruding pin feathers left after mechanical de-feathering. Protruding pinfeathers are the pinfeathers which have broken through the outer layer of skin, while non-protruding pinfeathers are the pinfeathers which have not pushed through the outer skin. The slaughtered ducks were eviscerated and dressed. The protruding pin feathers and non-protruding pin feathers of the dressed ducks were manually removed by hand and coun them all.

Statistical analysis

The two studies used a completely randomized design with three treatment diets and six replicate cages of 6 ducks each cage. Data collected from the studies were analyzed by analysis of variance using a Minitab14 Statistical Program (Minitab 2003). Differences among treatment means found in the analysis of variance were further tested by Tukey Test (Steel and Torrie 1980).


Results and discussion

The effect of enzymatically hydrolyzed feather meal in the broiler chicken diet on feed intake, body weight gain, feed conversion ratio (FCR), carcass weight and carcass percentage are shown in Table 3. The supplementation of the diets with enzymatically hydrolyzed feather meal improved feed intake, body weight gain, FCR, carcass weight and carcass percentage. Data on feather percentage, feather weight, number of pinfeathers, either protruding pinfeathers or non-protruding pinfeathers of the ducks at 7, 8, 9 and 10 weeks old fed the control diet and enzymatically hydrolyzed feather meal can be seen in Table 4. Feather percentage of ducks at 7 and 8 weeks old were higher in ducks fed the diets containing enzymatically hydrolyzed feather meal, but not in 9 and 10 weeks old ducks. Feather weight of ducks fed the feather meal treated with 0.01% enzyme (Allzyme FD) had heavier feather weight than those of the control ducks at all ages (7, 8, 9 and 10 weeks). The diets fed the enzymatically hydrolyzed feather meal had less protruding pin feather or non-protruding pin feather than those of the ducks fed the control diet.

Table 3. Effect of type of diets on final weight, body weight gain, feed intake, dry matter (DM) intake, FCR, carcass weight and carcass percentage of ducks kept for 10 weeks

Parameters

Treatments

P Value

SEM

CTL

EFM01

EFM02

Initial weight (g)

48.1

48.2

48.1

0.94

0.18

Final weight (g)

1243b

1447a

1477a

<0.001

25.6

Body weight gain (g)

1195c

1399b

1428a

<0.001

25.5

Daily gain (g/d)

17.1b

20.0a

20.4a

<0.001

0.37

Feed Intake (g)

6422c

6662a

6542b

<0.001

21.9

DM intake

5651b

5796a

5757a

<0.001

19.2

Protein intake (g)

1007b

1143a

1133a

<0.001

20.5

FCR

5.4a

4.8b

4.6c

<0.001

0.22

Carcass Percentage (%)

56.9b

57.9a

58.0a

<0.001

0.17

Carcass weight (g)

710b

841a

860a

<0.001

16.6

R1: control diet; R2: treated feather meal with 0.01% enzyme; R3: treated feather meal treated with 0.02% enzyme; SEM: Standard error means; FCR: Feed conversion ratio

Duck performance

The efficacy of using enzymes to improve the quality of the diet has been succesfully used in palm kernel meal diet (Iyayi and Davis 2005), soybean (Jackson et al 1999), barley (Classen et al 1985) and copra meal (Sundu et al 2008). The results of the current study on the effect of enzymatically hydrolyzed feather meal add up this consistency. Ducks fed the enzymatically hydrolyzed feather meal (EFM01 and EFM02) had higher body weight gain than the ducks fed the control diet (CTL). This might be due to the fact that ducks fed the enzymatically hydrolyzed feather meal diet ate more than the ducks fed the control diet, particularly in protein intake. Our study on digestibility of the same diets indicated that there was an improvement in metabolizable energy from 3257 kcal/kg for control diet to 3281 kcal/kg for either 0.01% or 0.02% of feather meal treated with Allzyme FD (Pertiwi, unpublished). The improvement in metabolizable energy, along with an improved protein intake might play roles of the increased body weight gain. Among the ducks fed the enzymatically hydrolyzed feather meal (EFM01 and EFM02), the supplementation of the diets with feather meal treated with 0.02% Allzyme FD (EFM02) had heavier body weight than the ducks fed the feather meal treated with 0.01% Allzyme FD (EFM01). Interestingly, this increase was nothing to do with feed intake since the ducks fed the feather meal treated with 0.02% Allzyme FD (EFM02) consume less diets than the ducks fed the diets supplemented with feather meal treated with 0.01% Allzyme FD (EFM01). This possibly indicates that there was an improvement in feather meal quality due to an increased concentration of enzyme in feather meal diet. Yuan et al (2008) found that relative activity of amylase in pancreas was increased by adding more enzyme in the diet. This might elaborate higher concentration of enzyme inclusion in the diet positively influence the quality of the diet.

Our findings also indicated that feed intake was also increased because of the supplementation of enzymatically hydrolyzed feather meal. The increase in feed intake was associated with an increase in body weight as heavier ducks consume more feed. It is not difficult to rasionalize this finding, due to the fact that the digestive tract on heavier ducks was bigger and thus could accommodate more digesta. Another possible reason is that increased feed intake might indicate that diet containing enzymatically hydrolyzed feather meal (EFM01 and EFM02) would speed up the flow of the digesta in the digestive system of broilers (Sundu 2009). Feed conversion ratio was also improved due to the supplementation of the diets with feather meal treated with Allzyme FD. It is understandable that when the body weight gain increased, FCR was improved.

Carcass percentage

The supplementation of the diets with feather meal treated enzyme increased carcass weight from 710 g (control ducks) to between 841 g and 860 g for ducks fed the enzymatically treated feather meal. The inclusion of 5% enzymatically hydrolyzed feather meal in the diet increased protein concentration of the diet by about 3%. The increase in protein diet due to feather meal inclusion probably helped to increase protein intake and availability for muscle growth and thus increase in carcass weight. It is also clear from the data that carcass weight curvilinearly improved over the increased enzyme concentration of treated feather meal (Y= 718.9 X 0.181; R2= 0.89). However, the increase in enzyme concentration from 0.01% (EFM01) to 0.02% (EFM02) did not enhance feather weight.

Ambara et al (2013) fed Bali duck with commercial diet and found that carcass weight of Bali duck at 9 weeks old was 865.5 g. These current findings indicate that the Bali ducks fed 5% enzymatically hydrolysed feathre meal in the diet were smaller than the previous findings of Ambara et al (2013). The difference in carcass weight was possibly due to different quality of diet in which Ambara et al (2013) used commercial diet while this present study used diet containing feather meal treated enzyme.

The same trend was also found in carcass percentage as carcass percentage is highly correlated to carcass weight. The inclusion of enzymatically hydrolyzed feather meal in the diet increased carcass percentage by about 1.8 to 1.9%. Increasing concentration of enzyme when treated to feather meal did not improve carcass percentage.

Feather growth

Wiradhana et al (2013) reported that Bali ducks at 10 weeks, feathers accounted for 6-7% of body weight. The percentage of feather in this current study was much lower, only about 3%. A couple of possible reasons related to the different feather percentage were experimental diets used and the temperature. We conducted our study at Palu Central Sulawesi, located exactly in the equatorial line which had warmer temperature (35 oC during the day) than the study site of Wiradhana et al (2013). The cooler temperature, coupled with the commercial diets used by Wiradhana et al (2013), produced ducks with more and heavier feather than our current findings.

Table 4. Feather percentage, feather weight and number of pinfeathers of ducks fed the diets supplemented with or without enzymatically hydrolysed feather meal.

Parameters

Treatments

P Value

SEM

CTL

EFM01

EFM02

Feather Percentage (%)

Week 7

2.5b

2.9a

3.0a

<0.001

0.058

Week 8

2.6b

2.9a

3.1a

<0.001

0.060

Week 9

2.9a

2.9a

3.0a

0.89

0.053

Week 10

3.2a

3.4a

3.2a

0.089

0.055

Feather weight (g)




Week 7

27.3b

33.7a

35.1a

<0.001

0.88

Week 8

29.8c

34.5b

37.4a

<0.001

0.84

Week 9

36.0b

38.1a

37.0ab

0.001

0.30

Week 10

43.1b

49.0a

46.8ab

0.017

0.91

Total number of PPF (pins)

Week 7

982a

769b

723c

<0.001

27.7

Week 8

670a

597b

572c

<0.001

5.67

Week 9

878a

749b

712c

<0.001

15.1

Week 10

934a

662b

602c

<0.001

15.7

Total number of NPPF (pins)

Week 7

812a

551b

348c

<0.001

46.3

Week 8

462a

384b

362b

<0.001

7.0

Week 9

303a

231b

222b

<0.001

6.9

Week 10

455a

291b

251c

<0.001

21.8

Number of PPF/kg BW

Week 7

899a

664b

622c

<0.001

7.72

Week 8

591a

506b

482c

<0.001

4.84

Week 9

717a

602b

569b

<0.001

12.16

Week 10

686a

465b

417c

<0.001

11.36

Number of NPPF/kg BW

Week 7

744a

476b

299c

<0.001

10.6

Week 8

408a

326b

305c

<0.001

5.99

Week 9

248a

186b

178b

<0.001

5.52

Week 10

334a

205b

173c

<0.001

17.1

R1: control diet; R2: treated feather meal with 0.01% enzyme; R3: treated feather meal treated with 0.02% enzyme; SEM: Standard error means; FCR: Feed conversion ratio; PPF: Protruding pinfeathers; NPPF: Non protruding pinfeathres; BW: Body weight

Feather percentage of ducks fed the diets with enzymatically hydrolyzed feather meal (EFM01 and EFM02) was higher than the control ducks at weeks 7 and 8. However, when the ducks got older (weeks 9 and 10), feather percentage of all ducks were statistically the same. The rationale of the increase in feather percentage of ducks fed the control diet at weeks 9 and 10 may be through a couple of reasons. First, when ducks got older, they consume more feed and thus more nutrients intake. Higher nutrients consumption of older ducks might be enough to produce an optimal feather growth. Second, this is only a matter of proportion of feather weight to body weight. Since the control ducks grow more slowly, in terms of body weight, feather percentage at weeks 9 and 10 was high and thus closed to those ducks fed the enzymatically treated feather meal. However, ducks fed the feather meal treated with 0.01% enzyme concentration had more and heavier feather than those of ducks fed the control diets at all ages (weeks, 7, 8, 9 and 10). The increase in feather percentage of ducks at weeks 7 and 8 might indicate that feather growth of ducks fed the enzymatically hydrolyzed feather meal (EFM01 and EFM02) was earlier and faster than those ducks fed the control diets in weeks 7 and 8. This is understandably due to the fact that diets with feather meal provide more amino acids, (particularly threonine and methionine) that are needed for the growth of feather.

The effect of diets on the growth and number of pinfeathers of ducks has not been reported in the data base. The presence of pinfeathers on the carcass made the carcasses look dirty and downgrade carcass quality. Accordingly, to improve carcass appearance and quality, the carcass should be free from pinfeathers. The number of protruding pinfeathers and non-protruding pinfeathers of ducks fed the control diets (CTL) was more than those ducks fed the enzymatically hydrolyzed feather meal diets (See Picture 1). This indicates that the quality of the carcass of ducks fed the control diets was adversely affected due to the presence of high number of pinfeathers. Supplementation of the diets with feather meal treated with enzyme decreased the number of protruding pinfeathers by about between 32 and 39% and non-protruding pinfeathers by about between 39 and 48% at week 10. It can be said that the supplementation of the diets with feather meal treated enzyme speeded up the growth of feather and thus made feathers grow longer. The long feather would be easily plucked during the mechanical de-feathering process and made the carcass of ducks fed enzymatically hydrolyzed feather meal had less pinfeathers. Accordingly, this particular treatment could produce better quality of carcass.


Picture 1.
pin feathers on the carcass of ducks t week 10


Conclusions


Acknowledgements

The authors wish to express special thanks to The head of department of Animal Husbandry, The University of Tribhuwana Tungga Dewa, Malang, for providing us research facilities. We are indebt to the Ministry of Research, Technology and Higher Education for financial support of this experiment.


References

Ambara A A, Suparta I N and Suasta I M 2013 Performan itik Cili (persilangan itik Peking itik Bali) umur 1-9 minggu yang diberi ransum komersial dan ransum buatan dibandingkan itik Bali. Jurnal Peternakan Tropika. 1: 20- 33

Brebu M and Spiridon I 2011 Thermal degradation of keratin waste. Journal of Analytical Applied Pyrolysis 91: 288-295

Classen H L, Campbell G L, Rossnagel B G, Bhatty R S and Reichert R R 1985 Studies on the use of hull less barley in chick diets: Deleterious effects and methods of alleviation. Canadian Journal of Animal Science, 65: 725-733.

Dirjent Jenderal Peternakan dan Kesehatan Hewan 2015 Statistik Peternakan Dan Kesehatan Hewan 2015. Direktorat Jenderal Peternakan dan Kesehatan Hewan Kementerian Pertanian Republik Indonesia

Galván I and Solano F 2016 Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution. International Journal of Molecular Science 17: 520–541

Iyayi E A and Davis B I 2005 Effect of enzyme supplementation of palm kernel meal and brewer’s dried grain on the performance of broilers. International Journal of Poultry Science 4: 76-80

Jackson M E, Fodge D W and Hsiao H Y 1999 Effects of beta mannanase in corn-soybean meal diets on laying hen performance. Poultry Science 7: 1737-1741

Kormanjos S, Kostadinovic L, Popovic S, Njezic Z, Radovic V and Puvaca N 2015 Influence of Feathers hydrothermal processing on bioactive substances in obtained feather meal. Annals of Biological Research 6: 6-11

Minitab 2003 Minitab user's guide. Data analysis and quality tools. Release 14 for windows. Minitab Inc, Pennsylvania, USA

Mulia D S, Risna T Y, Maryanto H and Purbomartono C 2016 Pemanfaatan Limbah Bulu Ayam Menjadi Bahan Pakan Ikan Dengan Fermentasi Bacillus subtilis; The utilisation of feather meal fermented with Bacillus subtilis as fish feed. Jurnal Manusia Dan Lingkungan, 23: 49-57

NRC 1994 Nutrient Requirements of Poultry. National Academy Press, Washington, DC.

Rutkowski A, Jozefiak D, Fratczak M and Wiaz M 2003 A note on the nutrtional value of enzymatically hydrolyzed feather meal for broiler chickens. Journal of Animal and Feed Sciences 12: 299-305

Staron P, Banach M, Kowalski Z and Staron A 2014 Hydrolysis of Keratin materials derived from poultry industry. Proceedings of ECOpole 8: 2

Steel R G D and Torrie J A 1980 Principles and procedures of statistics. New York, McGraw Hill.

Sundu B 2009 Gastrointestinal response and passage time of pelleted diets in the digestive tract of broilers. International Journal of Poultry Science 8: 976-979

Sundu B, Kumar A and Dingle J 2008 The effect of proportion of crumbled copra meal and enzyme supplementation on broiler growth and gastrointestinal development, International Journal of Poultry Science 7: 511-515

Wiradhana A P, Siti N W and Ariana I N T 2013 Berat potong dan bagian offal external Itik Bali jantan yang diberi pakan komersial disubtitusi pollar dan aditif duck-mix. Peternakan Tropika 1: 9–19

Yuan J, Yao J, Yang F, Yang X, Wan X, Han J, Wang Y, Chen X, Liu Y, Zhou Z, Zhou N and Feng X 2008 Effects of Supplementing Different Levels of a Commercial Enzyme Complex on Performance, Nutrient Availability, Enzyme Activity and Gut Morphology of Broilers. Asian - Australian Journal of Animal Science 5: 69 -700


Received 23 August 2017; Accepted 31 October 2017; Published 1 December 2017

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