| Livestock Research for Rural Development 25 (6) 2013 | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
This study was carried out to determine the performance of broilers fed diets containing wild cocoyam meal (WCM) using sundrying, soaking or cooking as processing methods to improve its nutritive value as a replacement for maize in broiler diets. Seven experimental diets were formulated with diet 1 (control) containing 0% WCM, while diets 2 to 7 contained sundried (Su), soaked (So) or cooked (Co) wild cocoyam meal each at 10% and 20% inclusion levels respectively.Two hundred and fifty two (252) one-day old broiler chicks sourced from a commercial hatchery were allocated into 7 treatments of 12 birds in 3 replicates in a completely randomised design and dietary treatment lasting 56days.
Soaking and cooking significantly reduced the anti-nutritional factors in wild cocoyam meal better than sundrying. Final body weight, average weight gain and average daily weight gain were significantly different (P<0.05) among the treatments. Control, So10, Co10 and Co20 showed better utilisation of feed than Su10, Su20 and So20. However, total feed consumption and average daily feed intake were not significantly different among the treatments. There were no significant differences in the overall carcass characteristics between the control diets and the varying levels of inclusion. It can be concluded that soaking and cooking were adequate to remove toxic phytochemicals in wild cocoyam meal to tolerable levels for broiler diets and inclusion up to 20% is advisable. At this level, growth and carcass characteristics were not significantly affected compared to the control diet. However, sundrying may be used as a treatment method when inclusion level is limited to 10% of total ration.
Key words: anti-nutritional factors, oxalate, Taro, tannins, toxicity
The increasing cost of feed resources in livestock production have been identified as a serious impediment to meeting the demand for animal protein particularly in developing countries (Adejinmi et al 2000). Poultry production relies mainly on maize as the main energy source but it suffers intense competition as food for humans resulting in higher demand than supply, higher cost and thus lower profit margin for poultry producers. This scenario is worsened among smallholder producers who find it increasingly hard to break even under the present circumstances. However, the ever-increasing cost of poultry feeds with attendant increase in cost of poultry products (meat and eggs) makes it necessary to explore the use of alternative feed ingredients that are cheaper, locally available and of low human preference (Agbede et al 2002,Tuleun et al 2009). Non-conventional feedstuffs offer cheaper and less competitive alternatives to producers especially during periods of scarcity of specific ingredients. Wild cocoyam is an herbaceous perennial crop which produces underground roots as corms containing high levels of fine starch. The leaves and other foliage have been reported to contain high protein content and extensively used as soups in many cultures, the stem tuber is very rich in soluble carbohydrate (Rodríguez and Preston 2009). Utilisation of the corms as source of energy have been documented for poultry (Onu et al (2006), leaves and foliage as source of protein for pigs (Buntha et al 2008) and as a soup ingredient for humans (Agwunobi et al 2002, Hang et al 2011). Wild cocoyam yields high quantity of biomass and corms (Hang and Kien 2012), is drought hardy and tolerateswater logged conditions (Apata et al 2012, Hang et al 2013).
Limitations to the use of non-conventional feedstuffs like wild cocoyam in animal production include their digestibility, bulkiness, palatability and more importantly the presence of anti-nutritional factors. These anti-nutritional factors have serious implication on the performance and health status of animals when considerable amounts are ingested in feed. They include Tannins, hydrocyanic acids, oxalates, antitrypsin inhibitors etc. Wild cocoyam corms have been reported to contain high content of oxalates, tannin, phytate and hydrocyanide (Okereke 2012, Hang and Binh 2013). Simple biotechnological methods such as soaking in water, dilute acids, sun-drying, toasting, boiling, cooking, ensiling etc. have been found suitable to destroy or reduce the anti-nutritional factors inherent in non-conventional feedstuffs and make them useful as livestock feed (Amaefule et al 2000). Various methods have been used in processing wild cocoyam, making them suitable for livestock consumption. Such treatment methods include ensiling the foliage (Hang and Preston 2010, Hang and Binh 2013), baking (Savage et al 2009), soaking in cow milk or coconut milk (Savage 2009) and in the underground corms by cooking (Agwunobi et al 2002, Onu 2006, Olajide et al 2011), soaking in water (Onu et al 2001, Ijadunola and Adejoro 2012) and sun-drying (Agwunobi et al 2002). The ability of a processing technique to reduce the anti-nutritional factors present in any feedstuff to safe levels or improve its utilisation potential will thus justify its continued use as a processing method in livestock feed processing. The objective of this study is to compare sun-drying, soaking and cooking in boiling water on the nutritive value of wild cocoyam meal, its effect on performance and carcass characteristics of broilers at ten and twenty percent inclusion levels respectively.
The experiment was conducted at the Teaching and Research farm, College of Animal Health and Production Technology, Moor Plantation, Ibadan, Oyo state in 2012.
Wild cocoyam was collected from the wild at Omi-Adio in Ibadan. The Root tubers were washed to remove dirt followed by chopping using kitchen knife. The chopped tubers were subjected to three different processing methods as a means of improving its nutritive value. The method of Uchegbu et al (2010) was used in preparing the sundried wild cocoyam meal. Washed tubers of wild cocoyam were sliced and spread on an even surface to sundry. Sundrying was done for seven consecutive days until crisp textured.Chopped wild cocoyam tubers were soaked by submerging in water for 9 days. The soaked tubers were removed from the water and dehydrated for 3 days until dry. This was followed by milling to obtain the soaked wild cocoyam meal (SOWCM) (Ijadunola and Adejoro 2012). Chopped wild cocoyam tubers were immersed in boiling water at 100oC and allowed to boil continuously for thirty minutes, cooled, drained and dehydrated. This method was previously described by Olajide (2010). Six experimental diets were formulated from the sun-dried, soaked and cooked wild cocoyam meal at 10% and 20% inclusion in a broiler diet for the performance trial.
A total of two hundred and fifty two day-old broiler chicks were sourced from a commercial hatchery in Ibadan and allocated into seven dietary treatments of twelve birds per treatment in three replicates. The birds were brooded and raised on a conventional open-sided deep litter house. All vaccination schedules and management procedures were followed. Feed and water were provided ad-libitum and the experiment lasted for 56 days.
Daily feed consumption was recorded as difference of feed offered and the left-over. Weight gain was measured weekly. Feed samples were collected for analysis.
Proximate composition of the wild cocoyam meals from the three processing methods was analysed using the method of AOAC (2000), while the presence of anti-nutritional factors were analysed as described for tannins by the Folin-Denis method (AOAC 1990), Oxalate (Oke 1966, Adeniyi et al 2009), Hydrocyanide (AOAC 1990) and Phytate (Stewart 1974).
Experimental data were subjected to analysis of variance (ANOVA) using SAS (2009) software. Means were separated with Duncan multiple range test at 5% level of significance.
Table 1 shows the chemical composition of the sundried, soaked and cooked wild cocoyam meal.The result shows that the effect of processing on the ether extract and ash content of the meal was not significantly (P<0.05) differentfrom each other. However, Crude protein and NFE were significantly reduced in the soaked and cooked wild cocoyam meal compared to the sundried meal. This may be attributable to solubilisation and leaching of soluble starch and other nutrient content of the meal as a result of the water treatment (Mbajunwa 1995). Levels of tannin, oxalates, phytates and hydrocyanide recorded were within the range reported by Olajide et al (2011). These anti-nutritional factors were significantly (P<0.05) reduced in the soaked and cooked meal as compared to the sundried meal. Levels of tannin recorded in all treatments were below 0.5-2.0% range reported as capable of depressing growth and egg production in poultry (Giner-Chavez, 1996). This result agrees with the findings of Ogun et al (1989). Sundrying alone may not be an effective method of reducing the toxic chemicals present in the meal to safe levels for poultry ration. The result of this study was also consistent with the findings of Ndimantang et al (2006) in a study where soaking in water, soaking in EDTA, cooking to doneness and roasting in fire were used as a means of reducing the oxalate, phytate and tannin content of two different cocoyam species. The result shows that all treatment methods significantly (P<0.05) reduced the total oxalate and phytate content but noted that the reduction of tannin was very slight and insignificant. Earlier results shows that boiling has been noted to leach the soluble oxalate content of the corms below detectable levels into the boiling water while baking method was observed to concentrate the oxalates into the tissue of the corms resulting in marginal oxalate reduction (Catherwood et al 2007). In Vietnam, Wild cocoyam has been noted to contain higher proportions of insoluble to total oxalate in leaves than in stems for most varieties (Hang and Binh 2013). Catherwood et al (2007) reported 60.6% proportion of soluble oxalate in total oxalate content of raw corms. Proportion of soluble to insoluble oxalate in a feed will influence the effectiveness of processing methods such as boiling, cooking, sundrying and baking because the ability of the oxalate to solubilise in solution and its heat susceptibility will influence the residual proportion. Specific solubility characteristic of the oxalate contents present in corms and foliage of wild cocoyam cultivars available in Nigeria have however not been well documented.
|
Table 1: Chemical composition of sundried, Soaked and Cooked wild cocoyam meal |
|||||
|
Composition (%) |
Sundried (Su) |
Soaked (So) |
Cooked (Co) |
SEM |
Prob. |
|
Dry Matter |
89.44 |
88.53 |
90.94 |
0.08 |
0.01 |
|
Crude Protein |
4.82a |
3.62b |
3.03b |
0.005 |
0.03 |
|
Crude fibre |
6.76 |
6.42 |
6.47 |
0.020 |
0.03 |
|
Ash |
3.10 |
3.02 |
2.98 |
0.030 |
0.10 |
|
Ether Extract |
0.73 |
0.55 |
0.48 |
0.67 |
0.11 |
|
NFE |
74.03a |
72.35b |
71.86b |
0.018 |
0.03 |
|
Anti-nutritional Factors (%) |
|||||
|
Oxalate |
0.75a |
0.41b |
0.35b |
0.002 |
0.07 |
|
Hydrocyanide |
4.18a |
3.24b |
3.28b |
0.001 |
0.06 |
|
Phytate |
1.25a |
0.25ab |
0.40b |
0.003 |
0.02 |
|
Tannin |
0.35a |
0.30a |
0.18b |
0.007 |
0.02 |
Table 2 and 3 shows the gross composition of the experimental diet as well as the performance of the broilers following the 56-day trial. This result shows that the inclusion of processed wild cocoyam meal did not significantly (P<0.05) reduce feed consumption of the birds in all treatment groups but weight gain was reduced with increasing inclusion levels in the three processing methods. Compared to control diet, feed utilisation was depressed significantly (P<0.05) in all test treatments except in the soaked wild cocoyam at 10% inclusion. Similarly, feed conversion ratio indicated that the most efficient utilisation of feed resources was in treatment1 followed by treatment 4,6,7,5, 2 and 3 respectively. Poorer weight gain in sundried wild cocoyam meal could be as a result of the phytochemicals interfering with the digestive processes. This was similar to the report of Abdulrashid et al (2009) who observed poor feed/gain value in broiler finisher diets containing uncooked cocoyam meal. Uchegbu et al (2010) showed that raw sundried cocoyam meal can be used in the diet of finisher broilers up to 15% inclusion level without being detrimental to their performance. However, 10% cocoyam inclusion level is the best in a single phase feeding in terms of daily weight gain and feed conversion ratio. Ten percent inclusion limit was similarly set by Apata et al (2012) for sundried wild cocoyam meal. Trypsin inhibitors and tannins have been implicated to depress nutrient absorption in animals by binding and precipitating proteins (Giner-Chavez, 1996). Highest weight gain was recorded in soaking at 10% inclusion (So10) followed by control diet, cooking at 10% inclusion (Co10), cooking at 20% inclusion (Co20), soaking at 20% inclusion (So20), sundrying at 10% (Su10) and sundrying at 20% (Su20) respectively.
The deleterious effects of feeding raw wild cocoyam meal to broiler chickens have been documented by Onu et al (2001). In that report, wild cocoyam meal caused depressed feed intake and reduced feed utilisation. This has been attributable to the presence of anti-nutritional factors ranging from phytates, oxalates, hydrocyanic acids and tannins. Oxalates have been reported to form complexes with mineral particularly calcium thereby making them unavailable to the body, cause irritation of the gut and resulting in low feed intake, inhibit protein and energy utilisation in broilers (Agwunobi 2002, Ndimantang et al 2006; Okereke 2012,). Phytates impairs the utilisation of protein and some minerals resulting in poor performance while tannins inhibits digestive enzymes and causes irritation of the gut. Not only does oxalate interfere with calcium absorption in the digestive tract, it also limits nitrogen retention (Hang and Preston 2009, Hang and Binh 2013). From the results of the average daily intake and weight gain, sundried wild cocoyam meal may be used in poultry ration only about 10% inclusion while soaking and cooking are adequate treatment methods when inclusion levels up to 20% is desirable. This result further validates the assertion of Onu et al (2006) that cooked wild cocoyam meal can be included in broiler finisher diet up to 20% of total ration.
|
Table 2: Gross Composition of Experimental Diets |
||||||||
|
Ingredient |
T1(Control) |
T2 (Su10) |
T3 (Su20) |
T4 (So10) |
T5 (So20) |
T6 (Co10) |
T7 (Co20) |
|
|
Maize |
54.00 |
44.00 |
34.00 |
44.00 |
34.00 |
44.00 |
34.00 |
|
|
SUWCM |
- |
10.00 |
20.00 |
- |
- |
- |
- |
|
|
SOWCM |
- |
- |
- |
10.00 |
20.00 |
- |
- |
|
|
COWCM |
- |
- |
- |
- |
- |
10.00 |
20.00 |
|
|
Soybean meal |
14.00 |
14.00 |
14.00 |
14.00 |
14.00 |
14.00 |
14.00 |
|
|
GNC |
15.55 |
15.55 |
15.55 |
15.55 |
15.55 |
15.55 |
15.55 |
|
|
PKC |
3.50 |
3.50 |
3.50 |
3.50 |
3.50 |
3.50 |
3.50 |
|
|
Wheat offal |
5.0 |
5.0 |
5.0 |
5.0 |
5.0 |
5.0 |
5.0 |
|
|
Fish meal |
5.00 |
5.00 |
5.00 |
5.00 |
5.00 |
5.00 |
5.00 |
|
|
Bone meal |
1.10 |
1.10 |
1.10 |
1.10 |
1.10 |
1.10 |
1.10 |
|
|
Oyster shell |
1.20 |
1.20 |
1.20 |
1.20 |
1.20 |
1.20 |
1.20 |
|
|
Salt |
0.20 |
0.20 |
0.20 |
0.20 |
0.20 |
0.20 |
0.20 |
|
|
*Premix |
0.25 |
0.25 |
0.25 |
0.25 |
0.25 |
0.25 |
0.25 |
|
|
Lysine |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
|
|
Methionine |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
0.10 |
|
|
Total |
100.00 |
100.00 |
100.00 |
100.00 |
100.00 |
100.00 |
100.00 |
|
|
Calculated analysis (%) |
||||||||
|
Crude Protein |
22.98 |
22.75 |
22.68 |
23.05 |
22.79 |
23.24 |
22.56 |
|
|
Crude fibre |
3.63 |
4.10 |
4.48 |
4.51 |
4.35 |
4.20 |
3.76 |
|
|
ME Kcal/g |
2979 |
2723 |
2967 |
2845 |
2980 |
3012 |
2946 |
|
|
*Contained per kg; Vit A, 12,000IU; Vit D3, 2000IU; Vit E, 7000; Vit b2, 4000mg; Nicotinic acid, 15,000mg; Calcium D-pentothenate, 8000mg; Biotin, 40mg; Vit b12, 10mg; Mn, 20,000mg; Fe, 50,000mg; Zn, 100,000mg; Cu, 10,000mg; Iodine, 750mg; Co, 3000mg. |
||||||||
|
Table 3: Growth performance of Broilers fed sundried, soaked cooked wild cocoyam meal at different levels of replacement for maize |
|||||||||
|
Parameters |
T1 (Control |
T2 (Su10) |
T3 (Su20) |
T4 (So10) |
T5 (So20) |
T6 (Co10) |
T7 (Co20) |
SEM |
Prob |
|
Initial body weight |
96.43 |
103.00 |
102.00 |
107.33 |
97.67 |
105.00 |
104.00 |
2.57 |
0.25 |
|
Final body weight |
2140.90a |
1733.70b |
1644.40b |
2161.10a |
1765.60b |
2080.64a |
1952.36a |
73.28 |
0.36 |
|
Total weight gain |
2044.50a |
1630.70b |
1539.40b |
2053.80a |
1667.90b |
1975.64ab |
1848.36ab |
72.67 |
0.22 |
|
Av. wt gain (g/bird/day) |
36.51a |
29.17b |
27.55b |
36.67a |
29.79b |
35.28a |
33.01a |
1.29 |
0.17 |
|
Total feed consumption |
5174.10 |
5080.20 |
4792.60 |
5288.50 |
5081.30 |
5170.02 |
5188.64 |
86.20 |
0.11 |
|
Av. Daily intake |
92.39 |
90.72 |
85.58 |
94.44 |
90.74 |
92.32 |
92.65 |
1.54 |
0.03 |
|
FCR |
2.54b |
3.11a |
3.12a |
2.58b |
3.04a |
2.61b |
2.80b |
0.09 |
0.08 |
|
Mortality |
5.55 |
8.33 |
5.55 |
5.55 |
8.33 |
2.77 |
5.55 |
1.26 |
0.11 |
The result of the carcass characteristics are presented in Table 4. The result indicated that the cut parts and internal organs did not differ significantly (P<0.05) from the control diet. The internal organs showed no significant differences among the treatments. This is a preliminary indication that there was no hypertrophy of any of the visceral organs. Relative organ weight, lack of abnormalities or gross pathologic lesions in the liver and other internal organs have been indicative of the absence of toxicity arising from feedstuff (Amaefule et al 2005). Effect of processing was significant on the overall feed value of the wild cocoyam meal. Mortality recorded during the experiment did not show any trend attributable to the type of diets given the animals.
|
Table 4: Carcass Characteristics of Broiler Finishers Fed Graded levels of soaked Wild Cocoyam as partial replacement for Maize |
|||||||||
|
Parameters |
T1 (0%) |
T2 (Su10) |
T3 (Su20) |
T4(So10) |
T5(So20) |
T6(Co10) |
T7(Co20) |
SEM |
Prob. |
|
Live wt (g) |
2140a |
1733b |
1644b |
2161a |
1765b |
2080ab |
1848ab |
73.28 |
0.36 |
|
1Ewt |
80.31 |
80.00 |
81.31 |
79.15 |
80.15 |
81.15 |
79.60 |
0.43 |
0.03 |
|
1Dwt |
73.74a |
72.38ab |
74.80a |
70.79b |
73.44 |
74.91 |
71.30 |
0.53 |
0.01 |
|
2Breast |
25.39 |
23.42 |
25.65 |
23.55 |
25.40 |
24.21 |
23.52 |
0.50 |
0.02 |
|
2Back |
19.65 |
17.15 |
18.47 |
17.51 |
18.48 |
17.24 |
18.42 |
0.43 |
0.03 |
|
2Wing |
10.74 |
11.27 |
10.87 |
11.34 |
10.93 |
11.12 |
11.10 |
0.13 |
0.03 |
|
2Thigh |
15.23ab |
15.34a |
14.00b |
15.26ab |
15.24 |
14.02 |
14.36 |
0.23 |
0.01 |
|
2Drumstick |
12.88b |
14.00a |
13.35ab |
13.70ab |
13.44 |
13.24 |
12.87 |
0.23 |
0.01 |
|
2Neck |
6.40 |
5.35 |
5.27 |
5.87 |
5.46 |
6.24 |
6.18 |
0.30 |
0.03 |
|
2Head |
3.82 |
3.65 |
3.43 |
3.86 |
3.45 |
3.55 |
3.78 |
0.15 |
0.02 |
|
2Leg |
5.48b |
6.72a |
5.35b |
6.49a |
5.48b |
5.50b |
6.45a |
0.17 |
0.11 |
|
3Kidney |
0.70 |
0.67 |
0.53 |
0.63 |
0.60 |
0.55 |
0.58 |
0.04 |
0.01 |
|
3Gizzard |
4.34 |
4.11 |
4.29 |
4.61 |
4.10 |
4.30 |
4.25 |
0.11 |
0.08 |
|
3Heart |
0.71 |
0.86 |
0.75 |
0.72 |
0.82 |
0.79 |
0.81 |
0.11 |
0.00 |
|
3Lung |
0.74a |
0.95a |
0.76a |
0.75b |
0.81 |
0.73 |
0.75 |
0.03 |
0.01 |
|
3Liver |
2.56 |
2.62 |
2.68 |
3.00 |
2.63 |
2.59 |
2.61 |
0.09 |
0.01 |
|
3Spleen |
0.15 |
0.13 |
0.17 |
0.13 |
0.14 |
0.15 |
0.14 |
0.11 |
0.00 |
|
ab: means with the same superscript along the same row are not significantly different (P<0.05) Ewt-Eviscerated weight, Dwt-Dressed weight 1: Expressed as % of live weight 2: Expressed as % of Eviscerated weight 3: Expressed as % of Dressed weight |
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The result of this study shows that adequate soaking in water and cooking are sufficient methods of reducing the anti-nutritional factors in wild cocoyam to tolerable levels for broiler birds and inclusion up to 20% of ration is possible while sun-dried wild cocoyam contains significant oxalate content which limits its utilisation in broilers.
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Received 24 April 2013; Accepted 22 May 2013; Published 2 June 2013