| Livestock Research for Rural Development 30 (6) 2018 | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
The study investigated the effect of fat and enzyme on utilisation of cassava peel meal by broiler. Total of 250 Ross 308 broiler chicks, 10 d-old, were allotted to five diets consisting of a control and 4 diets containing CPM with fat and enzyme singly or in combination.
Feed intake, feed: gain, relative weights of carcass, thigh and drumstick were not affected (10-41 d). Weight gain was reduced (P<0.05) on CPM but addition of fat, enzyme or fat plus enzyme markedly improved weight gain. Breast muscle deposition was depressed on the groups fed CPM alone but this was corrected by fat or enzyme addition with the maximum deposition in the fat and enzyme supplemented groups. Enzyme supplementation resulted in a heavier liver while the weights of crop and pancreas were increased on CPM alone. There were no treatment effects on the relative weight of proventriculus and gizzard. Feeding CPM with challenzyme or fat plus enzyme reduced the weight of small intestine while caeca weight was increased on CPM fed alone. Replacement of 40% maize with CPM adversely affects broiler performance but enzyme and tallow supplementation restores performance. More research is recommended into higher levels of CPM, source and concentrations of fat and enzyme products and nutrient utilisation.
Keywords: alternative feed resources, diet composition, feed processing, broiler performance
The increasing world price of maize due to competition between food and biofuel industries has reduced its availability for poultry feeding. According to USDA (2015) the price of maize increased by about 71% from September 2005 to September 2015. There has been increased research interest into alternative cheap energy sources for poultry feeding. Cassava (Manihot esculenta) root has been used as energy source in poultry diets with promising results. Currently however, there is growing demand for cassava root for food and industrial uses, mainly starch production. During cassava processing for food and industrial uses, large quantities of peels are produced which are rarely utilised in most cassava producing countries. In 2009, Fiji was reported to have produced about 42,300 metric tons of cassava, which is slowly replacing other traditional food crops in Fijian diets (FAO 2009 cited in Babatunde 2013). Taking cassava peel as 13-20% of the tuber weight (Obadina et al 2006; Oladunjoye et al 2010) this would account for about 6,345 to 8,460 tonnes of cassava peel produced in Fiji in 2009. According to Babatunde (2013) this by-product still remains underutilized in Fiji and often poses disposal problems.
There are reports of the feeding of cassava peel meal to broilers but recommendations have been variable. The high fibre and low energy density, low protein content, dustiness and likely content of hydrocyanic acid (HCN) have limited the full utilisation of cassava peel in monogastric feeding (Ravindran 1991). Fat addition reduces dustiness and boosts the energy levels and of cassava peel meal based diets (Oke 1978). Many enzyme products have been used to improve the utilisation of dietary fibre by poultry (Tabook et al 2006; Sundu et al 2009). Hydrocyanic acid is heat labile which can be reduced below toxic levels by sun-drying (Eggum 1970; Osei 1990; Ravindran 1991). In addition, sweet cassava varieties have been bred for low HCN content.
Replacement of 20% maize with cassava peel meal had no adverse effect on broiler performance (Oyebimpe et al 2006) but 30% replacement was found to reduce feed intake and weight gain in both starter and finisher broilers (Tewe 1983; Odunsi et al 2001). Supplementation of cassava peel meal-based broiler diets with enzyme products (Midau et al 2011; Bhuyian et al 2012) and fat (Ogbonna and Adebowale 1993; Kana et al 2014) has been studied but combined effect of fat and enzyme in the diet is not reported. A preliminary study was undertaken to ascertain the effects of fat and challenzyme supplementation on the utilisation of high cassava peel meal-based by broiler chickens.
Peels of a sweet variety obtained from a cassava processing plant in the study area were washed under running tap water to remove soil, chopped and sun-dried. Dried peels were then ground in a hammer mill to pass through a 2 mm sieve and labelled cassava peel meal (CPM). The meal was analysed for proximate composition (AOAC 1990; Table 1) and used in the formulation of the experimental diets.
|
Table 1. Composition of cassava peel meal, maize and wheat (% DM) |
|||
|
Constituents |
Cassava peelA |
MaizeB |
WheatB |
|
Crude protein |
4.20 |
8.24 |
10.92 |
|
Ether extract |
1.40 |
1.98 |
1.82 |
|
Crude fibre |
12.70 |
2.00 |
2.57 |
|
NDF |
48.10 |
1.43 |
10.60 |
|
ADF |
15.20 |
4.51 |
5.55 |
|
Ash |
8.70 |
1.30 |
1.98 |
|
ME (MJ/kg) |
11.10 |
1.42 |
13.45 |
|
A analysed values (ME calculated); B values from https://feedipedia.org/ |
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Five broiler starter and finisher diets were formulated to meet the requirements of Ross 308 broiler chickens (Ross, 2007). The diets consisted of a control based on maize and wheat as main energy sources and 4 diets in which CPM replaced 40% maize (116 and 154g/kg CPM in the grower and finisher diets respectively) with different combinations of tallow and Challenzyme a complex enzyme with 8 enzyme activities (U/g): β-glucanase, 800; xylanase, 15,000; β-mannanase, 100; α-galactosidase,100; amylase, 500; pectinase, 500; protease, 8,000 and cellulose, 300 (Tables 2 and 3). Copra meal level was kept constant in the diets at both phases. All diets, formulated on digestible lysine and methionine basis, were fed as mash at both the grower and finisher phases.
The experimental protocol was approved by the Animal Ethic Committee of the University of the South Pacific. A total of 300 day-old Ross broiler chicks were brooded together on commercial starter feed for the first 9 days. On day 10 all chicks were weighed individually and 250 chicks of similar weights randomly allotted to 25 open-sided floor pens (1.5 m x 1 m) containing 10 birds each. The experimental diets were fed each to birds in 5 replicate pens in a completely randomized design. Grower feed was fed from 10 to 21 days and finisher from 22 to 41 days. Feed and water were provided ad-libitum throughout the period of the experiment. The lighting programme consisted of 22 h per day.
Growth performance data were collected on feed intake, weight gain and feed: gain. Feed intake and body weight gain were recorded weekly by difference. Feed: gain was calculated as the ratio of feed consumed to weight gained. Mortality was recorded daily and feed: gain values corrected for the body weight of dead birds.
At the end of the experiment (Day 41), 2 birds per pen having the closest body weight to the mean of the pen were fasted overnight, stunned electrically and euthanised by decapitation. Slaughtered birds were scalded at 50oC for about 1 min, plucked manually, eviscerated and dressed. The dressed chicken and major carcass cuts (breast meat, thighs and drumsticks) were weighed and expressed in relation to the weight of the live chicken.
Gut segments (proventriculus, gizzard, small intestine and caeca) with contents and annex glands (liver and pancreas) were also weighed using an electronic scale sensitive to 0.01 g and expressed in relation to the weight of the live bird.
Cassava peel meal was analysed in duplicate for proximate composition according to AOAC (1990). Dry matter was determined after 24 h in a forced-air oven (103oC). Nitrogen was analysed by Kjeldahl method (AOAC, ID 954.01) and crude protein calculated as nitrogen × 6.25 (feed factor). Total fat, ash and crude fibre were analysed according to AOAC (ID 942.05, 920.39, 962.09, 2002.04 and 973.18 respectively).
Growth, carcass, gut and gland data were subjected to one-way ANOVA (Steel and Torrie 1980) of the GLM in SPSS (SPSS for windows, version 22.0; IBM Corp., Armonk, NY, USA). Pen mean was the experimental unit for growth parameters while carcass, gut and gland weights were taken on individual birds. Treatment means were compared using the least significant difference and significant differences reported at P = 0.05.
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Table 2. Composition of the experimental grower diets (g/kg as fed basis) |
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|
Ingredients |
Grower (10-21 d) |
||||
|
Control |
CPM |
CPM + |
CPM + |
CPM + tallow |
|
|
Maize |
290 |
174 |
174 |
174 |
174 |
|
Wheat |
189 |
187 |
184.5 |
186 |
182.5 |
|
Tallow |
- |
- |
20 |
- |
20 |
|
CPM |
- |
116 |
116 |
116 |
116 |
|
Pea meal |
298 |
299 |
279 |
289 |
280 |
|
Fish meal |
72 |
73.5 |
75 |
75.5 |
74.5 |
|
Copra meal |
37 |
37 |
37 |
37 |
37 |
|
Meat meal |
85.5 |
85 |
86 |
87.5 |
84 |
|
Challenzyme |
- |
- |
- |
3.5 |
3.5 |
|
1 Premix |
2.5 |
2.5 |
2.5 |
2.5 |
2.5 |
|
Lysine HCl |
2 |
2 |
2 |
2 |
2 |
|
DL methionine |
1 |
1 |
1 |
1 |
1 |
|
Salt |
3 |
3 |
3 |
3 |
3 |
|
Sand |
20 |
20 |
20 |
20 |
20 |
|
2 Calculated composition |
|||||
|
Crude protein |
200 |
200 |
200 |
200 |
230 |
|
Crude fibre |
29.6 |
42.4 |
41.8 |
42.2 |
42 |
|
Ether extract |
43.4 |
42.5 |
46.3 |
43.0 |
41.8 |
|
Lysine |
12.6 |
12.8 |
12.7 |
12.8 |
12.7 |
|
Methionine |
6.1 |
6.2 |
6 |
6.3 |
6.1 |
|
ME (MJ/kg) |
121 |
120 |
122 |
123 |
122 |
|
1 Supplied/kg diet: retinol 6.71 mg, cholecalciferol 0.134 mg, α-tocopherol 23 mg, niacin 27.5 mg, thiamine 1.8 mg, riboflavin 5mg, pyridoxine 3 mg, cyanocobalamin 0.015 mg, menadione 2 mg, pantothenic acid 7.5 mg; biotin 0.06 mg, folic acid 0.75 mg, choline chloride 300 mg, cobalt: 0.2 mg, copper 3 mg, iodine 1 mg, iron 20 mg, manganese 40 mg, selenium 0.2 mg, zinc 30 mg, anti-oxidant: 1.25 mg. 2 NRC (2012) feed ingredient Table values were used for calculations. |
|||||
|
Table 3. Composition of the experimental finisher diets (g/kg as fed basis) |
|||||||||
|
Ingredients |
Finisher (22-41 d) |
CPM |
CPM + |
CPM + |
CPM + tallow |
||||
|
Maize |
385 |
231 |
231 |
231 |
231 |
||||
|
Wheat |
200 |
200 |
188.5 |
199 |
189.5 |
||||
|
Tallow |
- |
- |
25 |
- |
25 |
||||
|
CPM |
- |
154 |
154 |
154 |
154 |
||||
|
Pea meal |
200 |
197.2 |
180 |
188 |
170 |
||||
|
Fish meal |
50 |
52.3 |
52 |
54 |
57 |
||||
|
Copra meal |
57 |
57 |
57 |
57 |
57 |
||||
|
Meat meal |
79.5 |
80 |
84 |
85 |
84.5 |
||||
|
Challenzyme |
- |
- |
- |
3.5 |
3.5 |
||||
|
1 Premix |
2.5 |
2.5 |
2.5 |
2.5 |
2.5 |
||||
|
Lysine HCl |
2 |
2 |
2 |
2 |
2 |
||||
|
DL methionine |
1 |
1 |
1 |
1 |
1 |
||||
|
Salt |
3 |
3 |
3 |
3 |
3 |
||||
|
Sand |
20 |
20 |
20 |
20 |
20 |
||||
|
2 Calculated composition |
|||||||||
|
Crude protein |
190 |
190 |
190 |
190 |
190 |
||||
|
Crude fibre |
39 |
56.6 |
53.9 |
55.1 |
53.2 |
||||
|
Ether extract |
47.3 |
42.6 |
44.7 |
45.5 |
44.4 |
||||
|
Lysine |
10.8 |
11 |
11.1 |
11.2 |
10.8 |
||||
|
Methionine |
5.0 |
5.2 |
5.1 |
5.1 |
4.9 |
||||
|
ME (MJ/kg) |
129 |
127 |
130 |
127 |
128 |
||||
|
1 Supplied/kg diet: retinol 6.71 mg, cholecalciferol 0.134 mg, α-tocopherol 23 mg, niacin 27.5 mg, thiamine 1.8 mg, riboflavin 5mg, pyridoxine 3 mg, cyanocobalamin 0.015 mg, menadione 2 mg, pantothenic acid 7.5 mg; biotin 0.06 mg, folic acid 0.75 mg, choline chloride 300 mg, cobalt: 0.2 mg, copper 3 mg, iodine 1 mg, iron 20 mg, manganese 40 mg, selenium 0.2 mg, zinc 30 mg, anti-oxidant: 1.25 mg. 2 NRC (2012) feed ingredient Table values were used for calculations. |
|||||||||
The analysed composition of CPM and literature values for maize (Table 1) showed that cassava peel meal contained about 1.3, 1.5 and 2.0 times less ME, ether extract and crude protein respectively than maize. The test ingredient contained about 3 times more NDF, ADF, and 6 times more crude fibre than maize.
The growth performance results of the broilers are presented in Table 4. During the grower (10-21 d) period the group fed un-supplemented CPM consumed numerically less feed but the difference was not significant among diets. Weight gain was maximised on the group fed CPM supplemented with fat and challenzyme and depressed when CPM was fed alone. Birds fed CPM with fat and enzyme converted their feed better compared to those fed CPM alone or with fat. During the finisher phase (22-41 d), feeding CPM alone depressed feed intake compared to other CPM diets. Birds fed fat and enzyme supplemented CPM gained markedly more weight compared to the control, CPM alone and CPM plus fat. Feed: gain was not affected by dietary treatment. The overall growth period (10-41 d) showed no treatment effects on feed intake and feed: gain. Weight gain was significantly reduced on CPM but addition of tallow, enzyme or tallow and enzyme markedly improved gain.
|
Table 4. Growth performance of broilers fed cassava peel meal (400g/kg maize) with fat and Challenzyme |
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|
Parameters |
Control |
CPM |
CPM + |
CPM + |
CPM + Tallow |
SEM |
P value |
|
|
10-21 d |
||||||||
|
Feed intake (kg) |
5.02 |
4.8 |
5.12 |
5.19 |
5.11 |
0.146 |
0.399 |
|
|
Weight gain (kg) |
3.47ab |
3.21b |
3.42ab |
3.57ab |
3.71a |
0.207 |
0.022 |
|
|
Feed: gain |
1.44ab |
1.5a |
1.5a |
1.45ab |
1.38b |
0.131 |
0.020 |
|
|
22-41 d |
||||||||
|
Feed intake (kg) |
12.7ab |
11.77b |
13.15a |
13.07a |
13.87a |
0.606 |
0.034 |
|
|
Weight gain (kg) |
6.33c |
5.79d |
6.66bc |
7.01ab |
7.07a |
0.120 |
0.000 |
|
|
Feed: gain |
2.01 |
2.04 |
1.98 |
1.87 |
1.96 |
0.088 |
0.728 |
|
|
10-41 d |
||||||||
|
Feed intake (kg) |
17.7 |
16.6 |
18.3 |
18.3 |
19.0 |
1.498 |
0.444 |
|
|
Weight gain (kg) |
9.8b |
9.0c |
10.1ab |
10.6a |
10.8a |
0.226 |
0.002 |
|
|
Feed: gain |
1.81 |
1.85 |
1.81 |
1.73 |
1.76 |
0.059 |
0.648 |
|
|
SEM: standard error of the mean; abc: means within the row with different superscripts differ significantly. |
||||||||
Results of carcass measurements (Tables 5) showed no treatment effects on the relative weights of carcass, thigh and drumstick. Feeding CPM alone depressed breast muscle deposition but fat or enzyme addition corrected this depression. Breast meat deposition was maximised in broilers fed CPM with tallow and enzyme.
The results of glands and gut weights are presented in Table 6. Birds fed challenzyme supplemented CPM diet had significantly heavier liver. Liver weight did not differ between the control and other CPM-based diets. The relative weight of pancreas was markedly increased on CPM alone compared to challenzyme or fat and challenzyme supplemented CPM groups. The weight of pancreas did not differ between the control and CPM-based diets. A heavier crop was recorded on the control. Crop weight did not differ between the CPM fed groups. There were no treatment effects on the relative weight of proventriculus and gizzard. Feeding CPM with challenzyme or fat and Challenzyme significantly reduced the weight of small intestine. Birds fed CPM had heavier caeca compared to the groups fed the control, CPM plus enzyme and CPM plus fat and enzyme.
|
Table 5.
Relative weights of carcass and commercial cuts (g/100g live
weight) of broilers fed cassava peel |
||||||||
|
Parameters |
Control |
CPM |
CPM + |
CPM + |
CPM + Tallow |
SEM |
P value |
|
|
Carcass |
66.86 |
66.59 |
70.55 |
71.60 |
70.22 |
2.928 |
0.664 |
|
|
Breast |
15.60ab |
14.22b |
16.99ab |
16.34ab |
17.90a |
1.127 |
0.044 |
|
|
Thigh |
11.71 |
11.81 |
11.97 |
11.43 |
11.03 |
0.661 |
0.865 |
|
|
Drumstick |
9.39 |
10.33 |
10.01 |
10.24 |
9.66 |
0.433 |
0.530 |
|
|
SEM: standard error of the mean; ab: means within the row with different superscripts differ significantly. |
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|
Table 6.
Relative weights of gut segments (g/100g live weight) of
broilers fed of cassava peel meal (400g/kg |
||||||||
|
Parameters |
Control |
CPM |
CPM + |
CPM + |
CPM + Tallow |
SEM |
P value |
|
|
Liver |
2.06b |
2.13b |
2.20b |
2.59a |
2.10b |
0.115 |
0.013 |
|
|
Pancreas |
0.26ab |
0.29a |
0.25ab |
0.24b |
0.23b |
0.088 |
0.042 |
|
|
Crop |
0.99a |
0.22b |
0.21b |
0.22b |
0.23b |
0.152 |
0.019 |
|
|
Proventriculus |
0.52 |
0.43 |
0.51 |
0.47 |
0.47 |
0.048 |
0.768 |
|
|
Gizzard |
2.44 |
2.27 |
2.27 |
2.24 |
2.32 |
0.078 |
0.425 |
|
|
Small intestine |
4.37a |
4.29a |
4.22a |
3.28b |
3.61b |
0.221 |
0.021 |
|
|
Caeca |
0.38bc |
0.57a |
0.42ab |
0.24c |
0.35bc |
0.052 |
0.014 |
|
|
SEM: standard error of the mean; abc: means within the row with different superscripts differ significantly. |
||||||||
The protein content of CPM used in this study is within the range 4.6 to 5.5% reported by Morgan and Choct (2016) but Sogunle et al. (2009) and Adeyemo et al (2014) reported higher crude fibre and ether extract in CPM than our values. Several factors including cassava cultivar, agronomic practices, stage of maturity have been reported to affect the composition of cassava products (Eggum, 1970; Ravindran 1991). The higher crude fibre, NDF and ADF of CPM compared to maize was reflected in the CPM-based diets.
The reason for similarity in feed intake during the grower phase and subsequent suppression on CPM during the finisher was not clear but probably due to the lower energy requirement of young broilers on one hand and the level of CPM in the finisher diet (11.6 and 15.4% in the grower and finisher diets respectively) on the other hand. Weight gain was suppressed on CPM during both stages of growth confirming the inability of broilers to utilise high levels of dietary CPM. These results support earlier recommendations (10-15%) of CPM for broilers (Babatunde 2013; Oyebimpe et al 2006). Longer digesta retention of structural feed components is known to reduce feed intake in poultry (Rougière and Carré, 2010; Svihus 2011; Meremikwu et al 2013). The un-supplemented CPM during the finisher phase might have been retained longer resulting in reduced intake of this diet. This reduced feed intake with resultant lower intake of individual nutrients, especially amino acids, may explain the poorer weight gain of birds fed CPM without supplementation. Broilers are known to be sensitive to dietary amino acids balance in terms of weight gain and feed efficiency (Kidd et al. 2004). Fat or enzyme addition restored weight gain but the combined effect of fat and enzyme was greater suggesting that both low energy and complex structure limit the utilisation of CPM by broilers. These results are in agreement with earlier reports that addition of enzyme (Midau et al 2011), fat/palm oil (Kana et al 2014) improved weight gain, and feed utilisation of broilers fed cassava peel meal. The effect of fat addition on weight gain was pronounced during the finisher than the grower periods probably due to the inability of young birds to efficiently utilise dietary fat. Katongole and March (1980) and recently Diarra (2018) observed that the ability of broiler chickens to utilise dietary fat increases with age and attributed this to the inability of young birds to recycle bile salts efficiently.
Despite the differences in feed intake, the relative weights of carcass, thigh and drumstick were not affected by the diet. Hickling et al (1990) and Yalcin et al (1999) observed increased deposition of breast muscle with increasing levels of methionine. Reduced feed intake and resultant lower intake of this amino acid on CPM without supplementation may be a reason for the inhibition of breast deposition on this diet compared to the group fed CPM plus fat and enzyme. Fat and enzyme supplementation resulted in a greater breast deposition than the single effect of fat or challenzyme compared to the control and un-supplemented CPM. The improvement in breast muscle deposition on CPM plus fat and challenzyme further elucidates the need of both amino acids and energy for tissue synthesis. Because amino acid transport is energy dependent, increased energy availability from fat and enzymatic hydrolysis on the CPM diet with added fat and challenzyme may explain the observed pattern of breast muscle synthesis.
The heavier liver weight on CPM plus enzyme and its subsequent reduction on CPM plus tallow and enzyme in this study could not be explained. The pattern of pancreas weight suggests a higher activity of this organ on the CPM diet probably in an attempt to increase its hydrolytic activity on this diet. The reduced crop weight on the CPM-based diets may be due to i) lower feed intake on the un-supplemented diet as a result of slow digesta transit and ii) increased rate of digesta passage on the other CPM diets. The effect of enzyme and fat supplementation on feed transit time is documented. Dänicke et al (1999) observed increased digesta transit time in all segments of the gut of xylanase supplemented rye-based diets in broilers because of increased digestibility. Mateos et al (1982) also reported a linear increase in transit time with increasing poultry fat in the diet. The pattern of small intestine and caeca weights in this study may further support increased hydrolysis of challenzyme supplemented CPM diets.
The financial support from the Research Committee of Faculty of Business and Economics, the University of the South Pacific, is acknowledged. Fiji Ministry of Agriculture is acknowledged for providing space and feed milling facilities for the research.
Authors declare no conflict of interest
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Received 28 March 2018; Accepted 30 April 2018; Published 1 June 2018