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The replacement value of fish silage for fish meal in practical broiler rations
Biological Wastes 25 (1988) 117-125
The Replacement Value of Fish Silage for Fish Meal in Practical Broiler Rations Anthony D. Ologhobo, a Adebisi M. Balogun b & 'Bukola B. Bolarinwa a * Department of Animal Science, b Department of Wildlife and Fisheries Management, University of lbadan, Nigeria (Received 20 October 1987; revised version received 15 January 1988; accepted 22 January 1988)
ABSTRACT In a 9-week feeding experiment, 270 day-old broiler chicks were fed four dried fish silage-based diets as a substitute for fish meal. Optimum growth andfeed efficiency were obtained with fish meal and neutral maize-fish silage diets. The acidic maize-fish silage and acidic cassava-fish silage diets gave the poorest performance and the highest (P < 0"05) percentage mortality. Nitrogen- and lipid-retention values were significantly ( P < 0.5) influenced by dietary treatments. Metabolizable energy increased for fish meal but was uniformly low in allfish silage-based diets. The substitution offish meal byfish silage also significantly reduced broiler carcass quality. Total edible meat, breast cuts and weights of giblets offish meal and neutral maize-fish silage diets were not significantly different, but dressed and eviscerated carcass weights were significantly ( P < 0.05) highest in fish meal diets and lowest in acidic maize-fish silage and acidic cassava-fish silage diets. Costs offeed per kilogram diet and per kilogram body weight gain were only slightly reduced when fish silage substituted fish meal in broiler feed formulation.
INTRODUCTION Existing projections o f world f ood supply suggest that within the foreseeable future there is likely to develop an increasing deficiency o f the raw materials used in formulating feed concentrates for intensive or semi-intensive systems !17 Biological Wastes 0269-7483/88/$03.50 © 1988 Elsevier Applied Science Publishers Ltd, England. Printed in Great Britain
118
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of animal production. In Nigeria the problem is a dual one: that of overcoming decreasing food production to feed the ever-increasing population and that of foreign exchange scarcity. The lack of foreign exchange has made it impossible to import livestock feed ingredients to offset great shortages at home and this has resulted in a drastic decline in animal production. According to the Poultry Association of Nigeria (1985), broiler production witnessed a 75% reduction, from 8 million in 1984 to 2 million in 1985. The report in fact indicated that stock population decrease was embarked upon by farmers in order to meet increasing production costs which were largely dictated by feed ingredient non-availability. If the estimates above are reasonably valid, then at least part of the deficit will have to be made by encouraging the use of locally available raw materials. Several of these in relatively ample supply include residues from cereals and legumes, forest crops, animal by-products and fish wastes. Fish wastes may be ensiled to produce animal feed by processes which require less technology than for the production of fish meal (Rao & Gilberg, 1976). Balogun & Oyeyemi (1986) reported that with appropriate precautions in the preparation and handling of fish before ensilation, fish silage can be incorporated into nutritionally balanced diets for broiler chickens without detrimental effects on growth or carcass quality. Other studies (McNaughton et al., 1978; Kompiang et aL, 1980) have indicated that dietary levels of 100 g/kg and higher are possible and pose no problems for broiler chickens. The study reported in this paper was undertaken to test the effects of complete replacement of fish meal by fish silage made from herring fish wastes (offal) on the performance, carcass characteristics and economics of production of broiler chicks.
METHODS About 100 kg of herring (Clupea harengus) fish offal (head, fins and viscera) were obtained from Astra. Sea Foods in Lagos, Nigeria. These parts are usually discarded as waste during fish-canning operations. The offal was chopped into small pieces and ensiled in large plastic containers at room temperature for 3 days. To prevent the growth of moulds, spoilage and pathogenic bacteria, a pH of 4.5 was maintained (Tatterson, 1982). This pH was achieved by the addition of 850ml formic acid (1% by weight) and 1700ml hydrochloric acid (2%) to 80kg of fish offals. The mixture was thoroughly stirred and the containers agitated to ensure complete liquefaction. At the end of 3 days, a liquid fish silage product, in which all parts of the
Fish silage for broilers
119
fish were digested was obtained. This was divided into two equal parts; one part was neutralized to pH 7 using sodium hydroxide, while the other part was left at pH 4.5. The liquid fish silages were mixed with filler materials: 1 kg of acidic or neutral liquid fish silage was added to 0-5 kg of maize or cassava flour, plus 0.3kg of groundnut cake and 0"2kg of wheat offal. This preparation gave four fish silage products: acidic maize-fish silage, acidic cassava-fish silage, neutral maize-fish silage and neutral cassava-fish silage. These were sun dried in shallow trays for 5 days. A total of 270 day-old cobb broilers were divided into 15 groups of 18 chicks each, according to their body weights, and were randomly assigned to compartments. The chicks were kept in battery brooders with raised wire floors until they were 4 weeks old, after which they were transferred to floor pens. Five dietary treatments of three replicates each were used. A control diet containing fish meal was fed as one treatment and the four fish silage diets were formulated by replacing the whole of the fish meal with each of the acidic or neutral dried fish silage products (Table 1). All diets were calculated to provide 23.00% crude protein and 2900 kcal/g metabolizable energy, but TABLE 1 Composition of Experimental Rations (23% crude protein; 2900 kcai/kg ME)
Ingredients
Maize Groundnut cake Fish meal Fish silage Blood meal Dried brewers' grain Wheat offal Bone meal Oyster shell Salt Premix Palm oil
Control fish meal diet
Neutral maize silage
Acidic maize silage
Neutral cassava silage
Acidic cassava silage
54.6 19'4 6.0 -3.0 6"0 4"0 3.5 0-5 0-5 0.5 2'0
50.6 24-4 . 6.0 5"0 4-0 3"0 3.5 0'5 0.05 0"5 2.0
50-6 24.2
48-4 26.6
6.0 5.0 4.0 3"0 3-5 0-5 0-5 0-5 2"0
48.4 26.6 . 6.0 5.0 4"0 3'0 3-5 0"5 0.5 0-5 2-0
23.00 10.00 13"10 46-81 0-19 4"34
22"60 10-50 18.00 48.82 0-08 4.27
22-5 8-60 10-00 42"99 0-09 4.26
Determined chemical composition (% dry matter) Crude protein (N x 6"25) 22"99 22.60 Ether extract 10.00 I 1.00 Crude fibre 15.00 10-00 Carbohydrates 35"43 42.32 Ash 0'08 0-08 Gross energy (kcal/g) 4"07 4.36
.
.
6.0 5.0 4'0 3-0 3.5 0-5 0-5 0-5 2.0
120
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protein content was reduced to 20% at the finisher phase. Mortality was recorded as it occurred. The chicks were weighed individually at the beginning of the experiment, and weekly thereafter until they were 9 weeks old when the experiment was terminated. The food consumption of each group was recorded. At the end of the ninth week, three chickens whose body weights were closest to the mean of the group were selected and placed in metabolic cages with facilities for individual feeding, watering and collection of droppings. The droppings were collected on alternate days for a week and sprayed with 1% boric acid to reduce bacterial decomposition of protein. Samples for each bird were bulked, wrapped in aluminium foil and oven dried at 85°C for 24 h. Total dry weight of faeces, and feed consumption, were recorded. At the end of the metabolic studies, the three birds selected per replicate were killed by neck dislocation. Each bird was wet plucked, head and feet removed and the carcass eviscerated for calculation of dressing percentages. Proximate analyses of fish silage products, diets and faeces were carried out according to the procedures of the AOAC (1975). The gross energy (GE) values were determined with a ballistic bomb calorimeter and metabolizable energy (ME) values of diets calculated based on the total collection procedure. Dry matter digestibility and apparent retention of nitrogen and fat were calculated as the difference between the amount of the constituent contained in the diets and the faecal samples collected. All data were subjected to analysis of variance and the means separated by multiple range tests (Duncan, 1955). RESULTS The proximate compositions of the different fish silage preparations are shown in Table 2. The performance, cost of production, and nutrient utilization by experimental birds, expressed as means from triplicate pen observations, are shown in Tables 3 and 4. Feed intake was highest in birds fed on fish meal and neutral maize-fish silage rations, but significantly (P < 0.05) reduced in birds fed acidic maize-fish silage, acidic cassava-fish silage or neutral cassava-fish silage diets. Acidic cassava-fish silage gave the lowest (P < 0.05) feed intake, while the differences between fish meal and neutral maize-fish silage diets were not significant. Body weight gains followed a similar trend to feed intake. Gains on fish meal were, however, superior to those on neutral maize-fish silage diet. Cost of feed per kilogram body weight gain and cost per kilogram of diet were slightly lower for all fish silage-based diets than for the fish meal. Nitrogen- and lipid-retention values showed significant (P < 0.05) dietary differences. While the nitrogen-retention value was highest for fish meal but
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TABLE 2 Proximate Composition of Fish Silage Products (Herring offal: Head, Fins and Viscera) Final pH
4-5
Filler material (Liquid fish silage :filler ratio) Fish silage 1
4-5
Fish silage I
7.0
Maize :
0.5
1
0.3
0.5
0.3
0-5
Wheat offal 0-2
:
Wheat offal 0-2
Groundnut meal :
:
Wheat offal 0.2 Wheat offal
0-3
:
0-2
0.3
Cassava :
:
Groundnut meal :
Maize :
Fish silage 7-0
Groundnut meal :
Cassava :
Fish silage 1
4.5 4.5 7.0 7-0
0'5
Groundnut meal :
Moisture 1%)
Protein (N x 6"25)
Oil (%)
Crude fibre (%)
Ash (%)
Gross energy (kcal/g)
10-00 9-68 9-76 10-35
34.1 30-8 ! 30.90 26.48
11.0 14.5 14.0 11.0
5.12 5.42 5.55 5.33
0-14 o- 16 0.13 0-13
4.20 4.00 4.32 4.05
s i g n i f i c a n t l y r o d u c e d in t h e fish silage diets, lipid r e t e n t i o n w a s l o w e s t in t h e fish m e a l a n d s i g n i f i c a n t l y ( P < 0"05) i n c r e a s e d in the s i l a g e - b a s e d diets. M e t a b o l i z a b l e e n e r g y v a l u e s r a n g e d b e t w e e n 3.01 a n d 3 . 5 0 k c a l / g , b e i n g s i g n i f i c a n t l y ( P < 0.05) h i g h e s t f o r t h e f i s h - m e a l d i e t a n d l o w e s t f o r a c i d i c c a s s a v a - f i s h silage. V a l u e s f o r n e u t r a l m a i z e - f i s h silage, a c i d i c m a i z e - f i s h TABLE 3 Performance and Economics of Production of Broilers on Fish Silage Diets Parameters
Fish meal diet
Neutral maize silage
Acidic maize silage
Neutral cassava silage
Acidic cassava silage
SE
Feed intake (kg) Body weight gain (kg/bird) Feed efficiency (food/gain) Mortality (%)
3-88° 1.51 ° 2.56 b 2.0c
3-71 ° 1"06b 3.50* 3.25 b
3.20 b 0"93~ 3.45* 4.37*
3.40 b 1'03 b 3.31 ° 3.45 b
3.05 b 0"89c 3.43* 4.66*
0-15 0.11 0.17 0.47
Cost of production: Cost of feed/kg body weight (-~) Cost of feed/kg diet (:N:)
0.16 0-66
0.12 0-60
0.13 0'61
0.12 0-61
0.12 0-61
0.01 0-01
Means differently superscripted are significantly different from one another (P < frO5).
A. D. Ologhobo et al.
122
TABLE 4 N u t r i e n t U t i l i z a t i o n by E x p e r i m e n t a l B i r d s F e d D i f f e r e n t F i s h Silage P r o d u c t s
Parameters
Fish meal control
Neutral maize silage
Acidic maize silage
Neutral cassava silage
Acidic cassava silage
SE
D r y m a t t e r digestibility ( % ) N i t r o g e n r e t e n t i o n (%) Lipid retention (%) Metabolizable energy (kcal/g) M E (kcal/g)
78-25 b 79-83 a 88.48 ~
86.33 ° 73.75 b 94-87 °
85-80 a 72.78 n 93.66 °
84-00 ° 72.88 b 93'83 °
84"60 ° 71-89 b 90.17 °h
1.44 1"43 1-22
3.14 b 2.87 b
3.01 b 2-72 b
0.13 0-09
73-54 b
70.66 b
2.64
Efficiency o f e n e r g y utilization (ME/GE%)
3.50 ° 3.27 ° 86.00 °
3.29 °b 3.10 ° 75-46 b
3.20 b 3.05 "b 73.73 b
M e a n s differently s u p e r s c r i p t e d a r e s i g n i f i c a n t l y different f r o m o n e a n o t h e r ( P < 0.05).
silage and neutral cassava-fish silage diets were significantly similar, although the value for neutral maize-fish silage was slightly higher than those for acidic maize-fish silage and neutral cassava-fish silage diets. Efficiency of energy utilization (ME/GE%) of fish meal was significantly (P < 0-05) higher than those of the fish silage diets. TABLE 5 C a r c a s s Q u a l i t y o f E x p e r i m e n t a l Broilers ( % B o d y Weigh't)
Carcass parameters
Dressed carcass Eviscerated carcass Total edible meat A b d o m i n a l fat Total bones Breast cut Back cut Drumstick Wing Neck Thigh Giblet Liver Heart Spleen Gizzard
Fish meal control 70.82 ° 62.05 ° 53.69* 1' 18 8.47* 12.94" 17.00 ° 16-36 ° 11-69 3-11 12.70 4.95 ° 2.54 0-47 0.10 2-49
Neutral maize silage 65.11 b 57.10 b 51-67 ° 1-09 5-32 b 10.43 ° 14.73 Qb 14.74 ° 10'66 2.87 11-69 4-024 2-50 0-44 0-10 2-36
Acidic maize silage 61.90 c 54.65 h 46.15 b 1.00 7.47 °b 9'56 °b 12-62 b 14-00 °b 9-04 2.70 10.85 3.74 b 2.63 0.43 0.09 2.22
Neutral cassava silage
Acidic cassava silage
SE
63.15 ~ 56-15 b 50-91 ° 1-10 6-00 b 9-87 °b 14.80 °b 13-86 b 10-70 3-00 11-61 3.88 °b 2-52 0-43 0.11 2-30
61.38 c 54.31 b 45'49 b 0-97 8'73 ° 9"00 b 12.40 b ! 1-60 b 9.00 2"69 11.00 3.44 b 2-49 0"41 0-08 2' 17
1.71 1"39 1.60 0-04 0.67 (}68 0.84 0'77 0-52 0-08 0.33 0-25 0.02 0-001 0.001 0.06
M e a n s differently s u p e r s c r i p t e d a r e s i g n i f i c a n t l y different f r o m o n e a n o t h e r ( P < 0"05).
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123
Data on carcass-quality parameters are summarized in Table 5. Dressed carcass, eviscerated carcass and total edible meat, expressed as percentages of live weight, showed significant (P < 0-05) treatment differences. In all cases, values were significantly higher for the diet containing fish meal than for diets containing fish silage. Also, values for acidic maize-fish silage and acidic cassava-fish silage diets were consistently lower than those for neutral maize-fish silage and neutral cassava-fish silage diets. Total bones were, however, similar in fish meal, acidic cassava-fish silage and acidic maize-fish silage diets but were significantly reduced in neutral cassava-fish silage and neutral maize-fish silage diets. DISCUSSION The crude protein levels obtained for the four dried silage products were much higher than values reported for liquid silage produced from herring fish offal by Tatterson (1982). The difference may be attributed to the effect of the fillers which raised significantly the crude protein content, and the drying which had a concentrating effect on the nutrients. This is consistent with the views of Balogun & Oyeyemi (1986) who have noted that the incorporation of fillers and drying had highly significant effects on the protein content of fish silage products. Judging from the present results, neutralization with sodium hydroxide appeared not to produce any significant effect on the protein content of the dried silage products. The performance of experimental birds showed that poorer feed intake, lower growth rate and reduced feed-efficiency were observed in broiler birds fed the various silage-based diets. However, while feed intakes of birds on acidic silage products were significantly lower than those on the control diet, neutralization improved feed intake of birds maintained on neutral maizefish silage ration was improved compared with that of the control. Body weight gains of the control group were higher than all other groups of birds. Fish waste may be ensiled to produce an animal feed by processes which require less technology than those used for the production of fish meal. McNaughton et al. (1978) and Kompiang et al. (1980) reported no adverse effect on growth when dried fish silage was included in the diet of broiler chickens. The present results are not in agreement with this observation but are consistent with the reports of Rao & Gilberg (1976), who showed that dietary fish silage can induce high mortality and depress growth of broiler chickens. In fact, significantly higher mortality rates and growth depression were attained with acidic silage diets than with the control and the neutralized silage diets. These observations may be explained by the fact that the acidic silage diets contained a high residual level of acid and may therefore have an acidic taste which resulted in lower feed intakes (Table 3).
124
A.D. Ologhobo et al.
This could also explain the growth depression and higher mortality rates observed in these groups of birds. Wirahadikusumah (1969) has explained that palatability and flavour due to high acidity are two important factors in the nutritional evaluation of acidic silage products. Of more importance in the present study, are the likely problems of amino acid balance and lipid oxidation products in the dried silage products. Amino acid composition of any feeding stuff is very important in determining its quality and value in the diet (Spencer, 1976). Although the amino acid composition of these products was not determined due to lack of facilities, there are reports which show that methionine (Jensen & Schmidtsdoff, 1977), tryptophan and histidine (Keay & Hardy, 1978) are growth limiting in fish silage. For acidic fish silage, Jensen & Schmidtsdoff (1977) have presented evidence to show that methionine and tryptophan are destroyed during the acid liquefaction process, thus accentuating the critically low level ofmethionine in the raw material. Histidine on the other hand is quickly degraded by spoilage bacteria at neutral pH and may be decomposed by enzymes in an acid silage (Gilberg, 1977). The relatively poor performance of the acidic silage products may be due to incomplete and imbalanced amino acid composition resulting from the destruction of these essential amino acids. It is also possible that the poor growth and performance of birds might have been caused by the presence of lipid oxidation products. Disney et aL (1978) showed that hydroperoxides were formed in relatively high amounts and were stable in a silage/carbohydrate feed. Hydroperoxides and secondary carbonyl products of lipid oxidation (Labuza, 1971) may react with proteins and amino acids (lysine) and thus cause some reduction in nutritional value. Generally, weakness and vitamin deficiency symptoms were also observed among the birds fed the different silage diets. These effects were drastically reduced when a vitamin formula was added to their drinking water after routine medication at 2, 3 and 6 weeks. This observation showed that some vitamins were also destroyed by oxidized lipids and is in agreement with the reports of Rao & Gilberg (1978) and Hansen et al. (1979). They reported that vitamins A, Bt, C and E could be destroyed by oxidized lipids already present in a silage/carbohydrate mixture. The substitution of fish meal by fish silage significantly reduced broiler carcass quality. This observation contradicts the work of Wirahadikusumah (1969), who reported that there were no significant effects on carcass cuts measured from the inclusion of acidic silage products up to a level of 10%. The data on costs of production show that it was cheaper to produce 1 kg of experimental diet when fish silage was used in the feed formulation than when fish meal was used. Fish meal was also more expensive than fish silage in the procurement of 1 kg of body-weight gain. Use offish silage would be a
Fish silage for broilers
125
great benefit to the poultry industry in Nigeria where at present the cost o f fish meal is prohibitive. However, as suggested by Balogun & Oyeyemi 0986), efforts should be made to make available simple equipment and materials that will aid the commercial production o f fish silage and silage products. It will also require considerable research effort to perfect production techniques and organized extension efforts to persuade poultry farmers to accept fish silage as a poultry feed component.
REFERENCES AOAC (1975). Official Methods of Analysis, 12th edn. Association of Official Analytical Chemists, Washington, D.C. Balogun, A. M. & Oyeyemi, I. E. (1986). Cost analysis of a small scale fish silage production from cannery wastes in Nigeria. J. West Afr. Fisheries, 2(1), 67-77. Disney, J. G., Hoffman, A., Olley, A., Barranco, A. & Francis, B. J. (1978). Development of a fish silage carbohydrate in animal feed for use in the tropics. Trop. Sci., 20(2), 129-37. Duncan, C. B. (1955). Multiple range and multiple F test. Biometrics, 11, 1-42. Giiberg, A. (1977). Properties of a propionic acid/formic acid in preserved silage cod viscera. J. Sci. Food Agric., 28, 647-56. Hansen, l., Graw, H. J., Steen, J. B. & Lysnes, H. D. (1979). Vitamin C deficiency in growing willow ptarmigan. J. Nutr., 109, 226-33. Jensen, I. & Schmidtsdoff, W. (1977). 'Fish silage'. Low fat and soluble fish protein products. In Proc. Syrup. I A F M M on Production and use offish meal, Szezean, Poland. Keay, J. N. & Hardy, R. E. (1978). Fish as food I. The fishers resources and its utilization process. Biochemistry, 13, 2-10. Kompiang, I. P., Arifudin, R. & Rao, J. (1980). Nutritional value of ensilaged bycatch fish from Indonesia shrimp trawlers. In Advances in Fish Science and Technology, ed. J. J. Connel. Fishing New Books, Farnham, Surrey, UK. Labuza, T. (1971). Kinetics of lipid oxidation in foods: Critical review. Food TechnoL, 2, 355-66. McNaughton, J. I., May, T. D., Reece, F. N. & Deaton, J. W. (1978). Broiler chick utilization of hydrolyzed fish protein. Poultry Sci., 1157-63. Poultry Association of Nigeria (1985). Communique report of the 9th Annual Conference of the PAN, held at Akure, Ondo State, Nigeria, 27-30 March. Rao, J. & Gilberg, A., (1976). Autolysis and proteolysis activity of cod viscera. J. Food TechnoL, II, 619-26. Spencer, H. (1976). Availability of proteins, minerals, and fluoride from fish protein concentrates. Clin. Nutr., 1, 28-34. Tatterson, I. N. (1982). Fish silage preparation, properties and uses. Food Sci. TechnoL, 9, 153-9. Wirahadikusumah, S. (1969). The effect of fish silage on the quality of hen's egg and meat of broilers. Lanthrukshogsk. Ann., 3J, 823-35.
The Replacement Value of Fish Silage for Fish Meal in Practical Broiler Rations Anthony D. Ologhobo, a Adebisi M. Balogun b & 'Bukola B. Bolarinwa a * Department of Animal Science, b Department of Wildlife and Fisheries Management, University of lbadan, Nigeria (Received 20 October 1987; revised version received 15 January 1988; accepted 22 January 1988)
ABSTRACT In a 9-week feeding experiment, 270 day-old broiler chicks were fed four dried fish silage-based diets as a substitute for fish meal. Optimum growth andfeed efficiency were obtained with fish meal and neutral maize-fish silage diets. The acidic maize-fish silage and acidic cassava-fish silage diets gave the poorest performance and the highest (P < 0"05) percentage mortality. Nitrogen- and lipid-retention values were significantly ( P < 0.5) influenced by dietary treatments. Metabolizable energy increased for fish meal but was uniformly low in allfish silage-based diets. The substitution offish meal byfish silage also significantly reduced broiler carcass quality. Total edible meat, breast cuts and weights of giblets offish meal and neutral maize-fish silage diets were not significantly different, but dressed and eviscerated carcass weights were significantly ( P < 0.05) highest in fish meal diets and lowest in acidic maize-fish silage and acidic cassava-fish silage diets. Costs offeed per kilogram diet and per kilogram body weight gain were only slightly reduced when fish silage substituted fish meal in broiler feed formulation.
INTRODUCTION Existing projections o f world f ood supply suggest that within the foreseeable future there is likely to develop an increasing deficiency o f the raw materials used in formulating feed concentrates for intensive or semi-intensive systems !17 Biological Wastes 0269-7483/88/$03.50 © 1988 Elsevier Applied Science Publishers Ltd, England. Printed in Great Britain
118
A.D. Ologhobo et al.
of animal production. In Nigeria the problem is a dual one: that of overcoming decreasing food production to feed the ever-increasing population and that of foreign exchange scarcity. The lack of foreign exchange has made it impossible to import livestock feed ingredients to offset great shortages at home and this has resulted in a drastic decline in animal production. According to the Poultry Association of Nigeria (1985), broiler production witnessed a 75% reduction, from 8 million in 1984 to 2 million in 1985. The report in fact indicated that stock population decrease was embarked upon by farmers in order to meet increasing production costs which were largely dictated by feed ingredient non-availability. If the estimates above are reasonably valid, then at least part of the deficit will have to be made by encouraging the use of locally available raw materials. Several of these in relatively ample supply include residues from cereals and legumes, forest crops, animal by-products and fish wastes. Fish wastes may be ensiled to produce animal feed by processes which require less technology than for the production of fish meal (Rao & Gilberg, 1976). Balogun & Oyeyemi (1986) reported that with appropriate precautions in the preparation and handling of fish before ensilation, fish silage can be incorporated into nutritionally balanced diets for broiler chickens without detrimental effects on growth or carcass quality. Other studies (McNaughton et al., 1978; Kompiang et aL, 1980) have indicated that dietary levels of 100 g/kg and higher are possible and pose no problems for broiler chickens. The study reported in this paper was undertaken to test the effects of complete replacement of fish meal by fish silage made from herring fish wastes (offal) on the performance, carcass characteristics and economics of production of broiler chicks.
METHODS About 100 kg of herring (Clupea harengus) fish offal (head, fins and viscera) were obtained from Astra. Sea Foods in Lagos, Nigeria. These parts are usually discarded as waste during fish-canning operations. The offal was chopped into small pieces and ensiled in large plastic containers at room temperature for 3 days. To prevent the growth of moulds, spoilage and pathogenic bacteria, a pH of 4.5 was maintained (Tatterson, 1982). This pH was achieved by the addition of 850ml formic acid (1% by weight) and 1700ml hydrochloric acid (2%) to 80kg of fish offals. The mixture was thoroughly stirred and the containers agitated to ensure complete liquefaction. At the end of 3 days, a liquid fish silage product, in which all parts of the
Fish silage for broilers
119
fish were digested was obtained. This was divided into two equal parts; one part was neutralized to pH 7 using sodium hydroxide, while the other part was left at pH 4.5. The liquid fish silages were mixed with filler materials: 1 kg of acidic or neutral liquid fish silage was added to 0-5 kg of maize or cassava flour, plus 0.3kg of groundnut cake and 0"2kg of wheat offal. This preparation gave four fish silage products: acidic maize-fish silage, acidic cassava-fish silage, neutral maize-fish silage and neutral cassava-fish silage. These were sun dried in shallow trays for 5 days. A total of 270 day-old cobb broilers were divided into 15 groups of 18 chicks each, according to their body weights, and were randomly assigned to compartments. The chicks were kept in battery brooders with raised wire floors until they were 4 weeks old, after which they were transferred to floor pens. Five dietary treatments of three replicates each were used. A control diet containing fish meal was fed as one treatment and the four fish silage diets were formulated by replacing the whole of the fish meal with each of the acidic or neutral dried fish silage products (Table 1). All diets were calculated to provide 23.00% crude protein and 2900 kcal/g metabolizable energy, but TABLE 1 Composition of Experimental Rations (23% crude protein; 2900 kcai/kg ME)
Ingredients
Maize Groundnut cake Fish meal Fish silage Blood meal Dried brewers' grain Wheat offal Bone meal Oyster shell Salt Premix Palm oil
Control fish meal diet
Neutral maize silage
Acidic maize silage
Neutral cassava silage
Acidic cassava silage
54.6 19'4 6.0 -3.0 6"0 4"0 3.5 0-5 0-5 0.5 2'0
50.6 24-4 . 6.0 5"0 4-0 3"0 3.5 0'5 0.05 0"5 2.0
50-6 24.2
48-4 26.6
6.0 5.0 4.0 3"0 3-5 0-5 0-5 0-5 2"0
48.4 26.6 . 6.0 5.0 4"0 3'0 3-5 0"5 0.5 0-5 2-0
23.00 10.00 13"10 46-81 0-19 4"34
22"60 10-50 18.00 48.82 0-08 4.27
22-5 8-60 10-00 42"99 0-09 4.26
Determined chemical composition (% dry matter) Crude protein (N x 6"25) 22"99 22.60 Ether extract 10.00 I 1.00 Crude fibre 15.00 10-00 Carbohydrates 35"43 42.32 Ash 0'08 0-08 Gross energy (kcal/g) 4"07 4.36
.
.
6.0 5.0 4'0 3-0 3.5 0-5 0-5 0-5 2.0
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A.D. Ologhobo et al.
protein content was reduced to 20% at the finisher phase. Mortality was recorded as it occurred. The chicks were weighed individually at the beginning of the experiment, and weekly thereafter until they were 9 weeks old when the experiment was terminated. The food consumption of each group was recorded. At the end of the ninth week, three chickens whose body weights were closest to the mean of the group were selected and placed in metabolic cages with facilities for individual feeding, watering and collection of droppings. The droppings were collected on alternate days for a week and sprayed with 1% boric acid to reduce bacterial decomposition of protein. Samples for each bird were bulked, wrapped in aluminium foil and oven dried at 85°C for 24 h. Total dry weight of faeces, and feed consumption, were recorded. At the end of the metabolic studies, the three birds selected per replicate were killed by neck dislocation. Each bird was wet plucked, head and feet removed and the carcass eviscerated for calculation of dressing percentages. Proximate analyses of fish silage products, diets and faeces were carried out according to the procedures of the AOAC (1975). The gross energy (GE) values were determined with a ballistic bomb calorimeter and metabolizable energy (ME) values of diets calculated based on the total collection procedure. Dry matter digestibility and apparent retention of nitrogen and fat were calculated as the difference between the amount of the constituent contained in the diets and the faecal samples collected. All data were subjected to analysis of variance and the means separated by multiple range tests (Duncan, 1955). RESULTS The proximate compositions of the different fish silage preparations are shown in Table 2. The performance, cost of production, and nutrient utilization by experimental birds, expressed as means from triplicate pen observations, are shown in Tables 3 and 4. Feed intake was highest in birds fed on fish meal and neutral maize-fish silage rations, but significantly (P < 0.05) reduced in birds fed acidic maize-fish silage, acidic cassava-fish silage or neutral cassava-fish silage diets. Acidic cassava-fish silage gave the lowest (P < 0.05) feed intake, while the differences between fish meal and neutral maize-fish silage diets were not significant. Body weight gains followed a similar trend to feed intake. Gains on fish meal were, however, superior to those on neutral maize-fish silage diet. Cost of feed per kilogram body weight gain and cost per kilogram of diet were slightly lower for all fish silage-based diets than for the fish meal. Nitrogen- and lipid-retention values showed significant (P < 0.05) dietary differences. While the nitrogen-retention value was highest for fish meal but
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TABLE 2 Proximate Composition of Fish Silage Products (Herring offal: Head, Fins and Viscera) Final pH
4-5
Filler material (Liquid fish silage :filler ratio) Fish silage 1
4-5
Fish silage I
7.0
Maize :
0.5
1
0.3
0.5
0.3
0-5
Wheat offal 0-2
:
Wheat offal 0-2
Groundnut meal :
:
Wheat offal 0.2 Wheat offal
0-3
:
0-2
0.3
Cassava :
:
Groundnut meal :
Maize :
Fish silage 7-0
Groundnut meal :
Cassava :
Fish silage 1
4.5 4.5 7.0 7-0
0'5
Groundnut meal :
Moisture 1%)
Protein (N x 6"25)
Oil (%)
Crude fibre (%)
Ash (%)
Gross energy (kcal/g)
10-00 9-68 9-76 10-35
34.1 30-8 ! 30.90 26.48
11.0 14.5 14.0 11.0
5.12 5.42 5.55 5.33
0-14 o- 16 0.13 0-13
4.20 4.00 4.32 4.05
s i g n i f i c a n t l y r o d u c e d in t h e fish silage diets, lipid r e t e n t i o n w a s l o w e s t in t h e fish m e a l a n d s i g n i f i c a n t l y ( P < 0"05) i n c r e a s e d in the s i l a g e - b a s e d diets. M e t a b o l i z a b l e e n e r g y v a l u e s r a n g e d b e t w e e n 3.01 a n d 3 . 5 0 k c a l / g , b e i n g s i g n i f i c a n t l y ( P < 0.05) h i g h e s t f o r t h e f i s h - m e a l d i e t a n d l o w e s t f o r a c i d i c c a s s a v a - f i s h silage. V a l u e s f o r n e u t r a l m a i z e - f i s h silage, a c i d i c m a i z e - f i s h TABLE 3 Performance and Economics of Production of Broilers on Fish Silage Diets Parameters
Fish meal diet
Neutral maize silage
Acidic maize silage
Neutral cassava silage
Acidic cassava silage
SE
Feed intake (kg) Body weight gain (kg/bird) Feed efficiency (food/gain) Mortality (%)
3-88° 1.51 ° 2.56 b 2.0c
3-71 ° 1"06b 3.50* 3.25 b
3.20 b 0"93~ 3.45* 4.37*
3.40 b 1'03 b 3.31 ° 3.45 b
3.05 b 0"89c 3.43* 4.66*
0-15 0.11 0.17 0.47
Cost of production: Cost of feed/kg body weight (-~) Cost of feed/kg diet (:N:)
0.16 0-66
0.12 0-60
0.13 0'61
0.12 0-61
0.12 0-61
0.01 0-01
Means differently superscripted are significantly different from one another (P < frO5).
A. D. Ologhobo et al.
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TABLE 4 N u t r i e n t U t i l i z a t i o n by E x p e r i m e n t a l B i r d s F e d D i f f e r e n t F i s h Silage P r o d u c t s
Parameters
Fish meal control
Neutral maize silage
Acidic maize silage
Neutral cassava silage
Acidic cassava silage
SE
D r y m a t t e r digestibility ( % ) N i t r o g e n r e t e n t i o n (%) Lipid retention (%) Metabolizable energy (kcal/g) M E (kcal/g)
78-25 b 79-83 a 88.48 ~
86.33 ° 73.75 b 94-87 °
85-80 a 72.78 n 93.66 °
84-00 ° 72.88 b 93'83 °
84"60 ° 71-89 b 90.17 °h
1.44 1"43 1-22
3.14 b 2.87 b
3.01 b 2-72 b
0.13 0-09
73-54 b
70.66 b
2.64
Efficiency o f e n e r g y utilization (ME/GE%)
3.50 ° 3.27 ° 86.00 °
3.29 °b 3.10 ° 75-46 b
3.20 b 3.05 "b 73.73 b
M e a n s differently s u p e r s c r i p t e d a r e s i g n i f i c a n t l y different f r o m o n e a n o t h e r ( P < 0.05).
silage and neutral cassava-fish silage diets were significantly similar, although the value for neutral maize-fish silage was slightly higher than those for acidic maize-fish silage and neutral cassava-fish silage diets. Efficiency of energy utilization (ME/GE%) of fish meal was significantly (P < 0-05) higher than those of the fish silage diets. TABLE 5 C a r c a s s Q u a l i t y o f E x p e r i m e n t a l Broilers ( % B o d y Weigh't)
Carcass parameters
Dressed carcass Eviscerated carcass Total edible meat A b d o m i n a l fat Total bones Breast cut Back cut Drumstick Wing Neck Thigh Giblet Liver Heart Spleen Gizzard
Fish meal control 70.82 ° 62.05 ° 53.69* 1' 18 8.47* 12.94" 17.00 ° 16-36 ° 11-69 3-11 12.70 4.95 ° 2.54 0-47 0.10 2-49
Neutral maize silage 65.11 b 57.10 b 51-67 ° 1-09 5-32 b 10.43 ° 14.73 Qb 14.74 ° 10'66 2.87 11-69 4-024 2-50 0-44 0-10 2-36
Acidic maize silage 61.90 c 54.65 h 46.15 b 1.00 7.47 °b 9'56 °b 12-62 b 14-00 °b 9-04 2.70 10.85 3.74 b 2.63 0.43 0.09 2.22
Neutral cassava silage
Acidic cassava silage
SE
63.15 ~ 56-15 b 50-91 ° 1-10 6-00 b 9-87 °b 14.80 °b 13-86 b 10-70 3-00 11-61 3.88 °b 2-52 0-43 0.11 2-30
61.38 c 54.31 b 45'49 b 0-97 8'73 ° 9"00 b 12.40 b ! 1-60 b 9.00 2"69 11.00 3.44 b 2-49 0"41 0-08 2' 17
1.71 1"39 1.60 0-04 0.67 (}68 0.84 0'77 0-52 0-08 0.33 0-25 0.02 0-001 0.001 0.06
M e a n s differently s u p e r s c r i p t e d a r e s i g n i f i c a n t l y different f r o m o n e a n o t h e r ( P < 0"05).
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Data on carcass-quality parameters are summarized in Table 5. Dressed carcass, eviscerated carcass and total edible meat, expressed as percentages of live weight, showed significant (P < 0-05) treatment differences. In all cases, values were significantly higher for the diet containing fish meal than for diets containing fish silage. Also, values for acidic maize-fish silage and acidic cassava-fish silage diets were consistently lower than those for neutral maize-fish silage and neutral cassava-fish silage diets. Total bones were, however, similar in fish meal, acidic cassava-fish silage and acidic maize-fish silage diets but were significantly reduced in neutral cassava-fish silage and neutral maize-fish silage diets. DISCUSSION The crude protein levels obtained for the four dried silage products were much higher than values reported for liquid silage produced from herring fish offal by Tatterson (1982). The difference may be attributed to the effect of the fillers which raised significantly the crude protein content, and the drying which had a concentrating effect on the nutrients. This is consistent with the views of Balogun & Oyeyemi (1986) who have noted that the incorporation of fillers and drying had highly significant effects on the protein content of fish silage products. Judging from the present results, neutralization with sodium hydroxide appeared not to produce any significant effect on the protein content of the dried silage products. The performance of experimental birds showed that poorer feed intake, lower growth rate and reduced feed-efficiency were observed in broiler birds fed the various silage-based diets. However, while feed intakes of birds on acidic silage products were significantly lower than those on the control diet, neutralization improved feed intake of birds maintained on neutral maizefish silage ration was improved compared with that of the control. Body weight gains of the control group were higher than all other groups of birds. Fish waste may be ensiled to produce an animal feed by processes which require less technology than those used for the production of fish meal. McNaughton et al. (1978) and Kompiang et al. (1980) reported no adverse effect on growth when dried fish silage was included in the diet of broiler chickens. The present results are not in agreement with this observation but are consistent with the reports of Rao & Gilberg (1976), who showed that dietary fish silage can induce high mortality and depress growth of broiler chickens. In fact, significantly higher mortality rates and growth depression were attained with acidic silage diets than with the control and the neutralized silage diets. These observations may be explained by the fact that the acidic silage diets contained a high residual level of acid and may therefore have an acidic taste which resulted in lower feed intakes (Table 3).
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A.D. Ologhobo et al.
This could also explain the growth depression and higher mortality rates observed in these groups of birds. Wirahadikusumah (1969) has explained that palatability and flavour due to high acidity are two important factors in the nutritional evaluation of acidic silage products. Of more importance in the present study, are the likely problems of amino acid balance and lipid oxidation products in the dried silage products. Amino acid composition of any feeding stuff is very important in determining its quality and value in the diet (Spencer, 1976). Although the amino acid composition of these products was not determined due to lack of facilities, there are reports which show that methionine (Jensen & Schmidtsdoff, 1977), tryptophan and histidine (Keay & Hardy, 1978) are growth limiting in fish silage. For acidic fish silage, Jensen & Schmidtsdoff (1977) have presented evidence to show that methionine and tryptophan are destroyed during the acid liquefaction process, thus accentuating the critically low level ofmethionine in the raw material. Histidine on the other hand is quickly degraded by spoilage bacteria at neutral pH and may be decomposed by enzymes in an acid silage (Gilberg, 1977). The relatively poor performance of the acidic silage products may be due to incomplete and imbalanced amino acid composition resulting from the destruction of these essential amino acids. It is also possible that the poor growth and performance of birds might have been caused by the presence of lipid oxidation products. Disney et aL (1978) showed that hydroperoxides were formed in relatively high amounts and were stable in a silage/carbohydrate feed. Hydroperoxides and secondary carbonyl products of lipid oxidation (Labuza, 1971) may react with proteins and amino acids (lysine) and thus cause some reduction in nutritional value. Generally, weakness and vitamin deficiency symptoms were also observed among the birds fed the different silage diets. These effects were drastically reduced when a vitamin formula was added to their drinking water after routine medication at 2, 3 and 6 weeks. This observation showed that some vitamins were also destroyed by oxidized lipids and is in agreement with the reports of Rao & Gilberg (1978) and Hansen et al. (1979). They reported that vitamins A, Bt, C and E could be destroyed by oxidized lipids already present in a silage/carbohydrate mixture. The substitution of fish meal by fish silage significantly reduced broiler carcass quality. This observation contradicts the work of Wirahadikusumah (1969), who reported that there were no significant effects on carcass cuts measured from the inclusion of acidic silage products up to a level of 10%. The data on costs of production show that it was cheaper to produce 1 kg of experimental diet when fish silage was used in the feed formulation than when fish meal was used. Fish meal was also more expensive than fish silage in the procurement of 1 kg of body-weight gain. Use offish silage would be a
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great benefit to the poultry industry in Nigeria where at present the cost o f fish meal is prohibitive. However, as suggested by Balogun & Oyeyemi 0986), efforts should be made to make available simple equipment and materials that will aid the commercial production o f fish silage and silage products. It will also require considerable research effort to perfect production techniques and organized extension efforts to persuade poultry farmers to accept fish silage as a poultry feed component.
REFERENCES AOAC (1975). Official Methods of Analysis, 12th edn. Association of Official Analytical Chemists, Washington, D.C. Balogun, A. M. & Oyeyemi, I. E. (1986). Cost analysis of a small scale fish silage production from cannery wastes in Nigeria. J. West Afr. Fisheries, 2(1), 67-77. Disney, J. G., Hoffman, A., Olley, A., Barranco, A. & Francis, B. J. (1978). Development of a fish silage carbohydrate in animal feed for use in the tropics. Trop. Sci., 20(2), 129-37. Duncan, C. B. (1955). Multiple range and multiple F test. Biometrics, 11, 1-42. Giiberg, A. (1977). Properties of a propionic acid/formic acid in preserved silage cod viscera. J. Sci. Food Agric., 28, 647-56. Hansen, l., Graw, H. J., Steen, J. B. & Lysnes, H. D. (1979). Vitamin C deficiency in growing willow ptarmigan. J. Nutr., 109, 226-33. Jensen, I. & Schmidtsdoff, W. (1977). 'Fish silage'. Low fat and soluble fish protein products. In Proc. Syrup. I A F M M on Production and use offish meal, Szezean, Poland. Keay, J. N. & Hardy, R. E. (1978). Fish as food I. The fishers resources and its utilization process. Biochemistry, 13, 2-10. Kompiang, I. P., Arifudin, R. & Rao, J. (1980). Nutritional value of ensilaged bycatch fish from Indonesia shrimp trawlers. In Advances in Fish Science and Technology, ed. J. J. Connel. Fishing New Books, Farnham, Surrey, UK. Labuza, T. (1971). Kinetics of lipid oxidation in foods: Critical review. Food TechnoL, 2, 355-66. McNaughton, J. I., May, T. D., Reece, F. N. & Deaton, J. W. (1978). Broiler chick utilization of hydrolyzed fish protein. Poultry Sci., 1157-63. Poultry Association of Nigeria (1985). Communique report of the 9th Annual Conference of the PAN, held at Akure, Ondo State, Nigeria, 27-30 March. Rao, J. & Gilberg, A., (1976). Autolysis and proteolysis activity of cod viscera. J. Food TechnoL, II, 619-26. Spencer, H. (1976). Availability of proteins, minerals, and fluoride from fish protein concentrates. Clin. Nutr., 1, 28-34. Tatterson, I. N. (1982). Fish silage preparation, properties and uses. Food Sci. TechnoL, 9, 153-9. Wirahadikusumah, S. (1969). The effect of fish silage on the quality of hen's egg and meat of broilers. Lanthrukshogsk. Ann., 3J, 823-35.