The utilization by broiler chickens of poultry offal hydrolysed in formic acid

Animal Feed Science and Technology, 11 (1984) 2 4 7 ~ 2 5 9 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

247

THE UTILIZATION BY BROILER CHICKENS OF POULTRY OFFAL HYDROLYSED IN FORMIC ACID

D.H. MACHIN, D.A. HECTOR, B.S. CAPPER and P.M. CARTER

Tropical Products Institute, 56/62 Gray's Inn Road, London WCLx 8LU (Gt. Britain) (Accepted for publication 30 March, 1984)

ABSTRACT Machin, D.H., Hector, D.A., Capper, B.S. and Carter, P.M., 1984. The utilization by broiler chickens of poultry offal hydrolysed in formic acid. Anim. Feed Sci. Technol., 11: 247--259. This paper described the preservation of poultry offal by autolysis in the presence of formic acid, the subsequent preparation of broiler feed ingredients by drying the hydrolysate on wheat middlings and maize, and three feeding experiments in which broiler chickens received feed containing the dry hydrolysate. The poultry offal hydrolysate (POH) supplied 3.0--6.7% of the feed dry matter. After drying onto wheat middlings or maize meal, the mixtures supplied 17.5--35.0% of the dry matter of the feeds. In two of the feeding experiments, PCtI gave a poorer performance of chickens than did fish meal reference feeds. This was not considered to be due to any palatibility problems or nutritional problems associated with the POH, but to the use of high levels of wheat middlings in the POH feeds. In the other experiment in which all the feeds contained high levels of wheat middlings, no difference in- performance was noted between POH feeds and the reference feed, and the performance of all chickens was equal to published standards for the breed used. When poultry offal was processed by rendering and then included in chicken feeds, the performance of the chickens was inferior to that of chickens fed on POH. Bacteriological examination of carcases and feeds demonstrated the absence of a number of potantially pathogenic bacteria. These experiments indicate that POH made as indicated in this paper is palatable to chickens and has potential for use in poultry feeds as a replacement for fish meal and animal proteins. The POH also has a high fat content and would appear to be ideally suited for use in developing countries where ingredients rich in high-quality protein or energy are often expensive or in short supply.

INTRODUCTION Waste products from slaughter houses and poultry processing plants are t r a d i t i o n a l l y h e a t - s t e r i l i z e d b e f o r e b e i n g u s e d i n a n i m a l f e e d s . W h e r e t h e q u a n t i t y o f w a s t e t o b e p r o c e s s e d is s m a l l o r i r r e g u l a r i n s u p p l y , o p e r a t i n g c o s t s o f t e n p r e v e n t p r e s e r v a t i o n i n t h i s w a y . T h i s f r e q u e n t l y re-

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248 suits in these resources n o t being utilized, often in situations such as in developing countries where there m a y be a local shortage of animal feeding stuffs. There exists a need for a small-scale technique particularly directed at the ~preservation of small and/or irregular quantities of material. Work on fish silage has demonstrated the feasibility of chemical preservation techniques with small and irregular supplies of fish (Tatterson and Windsor, 1974; Disney and Hoffman, 1976). One technique which is in c o m m o n use involves chopping the waste materials, mixing with formic acid and allowing autolysis to occur. In temperate conditions, this results in lique~ faction of the flesh in 2--3 days (Disney et al., 1978). This technique has been applied to broiler processing plant waste, and its value as a wet feed for pigs was studied in t w o growth studies (Francis and Turnbull, 1978; Machin et al., 1983). In the first study, it was shown that poultry offal hydrolysate (POH) providing 10% of the diet dry matter could replace meat and bonemeal in the diet o f growing pigs, whilst in the second study, 20% POH dry matter replaced good-quality fish meal in pig meat production. Owing to its high moisture content, POH has n o t been considered suitable for direct inclusion in conventional poultry diets. However, work with fish silage (Disney and Hoffman, 1976) has shown that silage can be dried o n t o a carrier, and this p r o d u c t can be used in poultry feeds. Therefore, the aim of these studies was to establish if POH dried onto carriers could be used successfully in broiler chicken feeds in ways suitable for application in developing countries. Three experiments are reported. In the first, POH dried onto wheat middlings was given to 7-day-old chicks at two inclusion levels and their feed intakes, growth and performance were compared with those of chickens fed on two reference diets; the first contained a commercial rendered poultry meal (RM} with 20% feathers, and the other contained good-quality fish meal. In the second experiment, the growth and performance of chicks given feeds containing a similar POH p r o d u c t to that used in Experiment 1, b u t with a much lower level of wheat middlings, were compared with those of chickens given a reference feed containing fish meal. In this experiment, day-old chicks were used and broiler starter and finisher feeds were prepared. The high energy concentration of the POH suggested that it could be used to increase the energy levels of feeds containing ingredients such as wheat milling offals, which are low in energy. Materials of this t y p e are frequently available in developing countries, whereas whole cereals have to be specially imported with limited foreign exchange. Foreign exchange savings have also led to considerable interest in the use of cassava as a feed energy source. Consequently, the third experiment examined the use of starter and finisher feeds containing a high proportion of either wheat middlings or cassava, on to which POH had been dried. The feed

249

intake, growth and performance of broiler chicks given these feeds were compared with those of birds given reference feeds containing fish meal. M A T E R I A L S AND METHODS

Production of a dry meal containing poultry offal hydrolysate Poultry offal consisting of the viscera, heads and toes o f eviscerated table birds, including a few livers and gizzards, was obtained in broadly biological proportions from a large poultry packing station. The offal was thoroughly washed in cold water and then coarsely g r o u n d through the 8-mm plate of a 0.7 kW H o b a r t electric mincer at a rate o f 5 kg min -1. Batches o f the minced offal (30 kg) were made into slurries by hand-mixing for 2 min with 12.5% water (on a volume to weight basis) before 3% (v/w) concentrated formic acid (95%) was added. The final mixture was stirred with w o o d e n paddles for a further 2 min. Acid fumes were evolved during addition of acid to the minced offals, so acid addition was carried o u t in a well-ventilated area, with the mixing bin covered with polythene sheeting. The acidified mixture was placed in covered high-density polypropytene bins (70 l) at an ambient temperature of 25°C and stirred for 5 min twice daily for 10 days. At the end of this t i m e , hydrolysis was considered complete and the poultry offal hydrolysate was a homogeneous and stable viscous liquid. Before production of a dried meal, an antioxidant (butylated h y d r o x y toluene) dissolved in propylene glycol was vigorously mixed into the wet hydrolysate at 150 m g k g -1 of the estimated fat content. The wet POH was then mixed with the appropriate carrier, at 20% b y weight of wheat middlings or 40% b y weight of maize meal. These proportions had been shown from previous experiments to be the minimum necessary for the production of dried meals that could easily be incorporated into feeds and had non-compactable crumbs (D.A. Hector, unpublished results, 1978). The resultant mixtures were spread on drying trays to a.depth of 2.5 cm, placed in an oven at 50°C, turned twice daily and dried for 3 days. After drying, the materials which could n o t be ground in a hammer mill owing to its high fat content was minced through the 4-mm screen of the mincer to ensure homogeneity.

Production of rendered poultry offal meal Poultry offal consisting of offal and blood in biological proportions together with 20% by weight of feathers was processed at a temperature of 125--130°C and a pressure of 2 atmospheres to produce a rendered full-fat poultry offal meal. Water was added to give a moisture content comparable with the hydrolysate (75%), and the meal was dried onto wheat middlings (20% by weight) in the same manner as the hydrolysate.

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Bacteriological assessment The POH dried onto wheat middlings (POHW) and the rendered meal (RM) prepared for Experiment 1 were microbiologically examined for the following bacteria, although no experiments were undertaken to measure recovery of added organisms: (a) total viable counts, 27 ° C, 37°C aerobic and 37°C anaerobic; (b) total spore counts, 37 and 55°C; (c) most probable number of cOliforms; (d) Staphylococcus aureus, Clostridium spp. and Salmonella spp. Facilities for examining viruses were not available for use with the experiments reported here; studies on this subject will be reported separately.

Chemical analysis Crude protein, ether extract, ash, calcium, phosphorus and salt (NaC1) determinations were carried out on the POH and RM before and after drying onto carriers (Table I) using methods given in the U.K. Fertilizers and Feedingstuffs (amendement) regulations (Ministry of Agriculture, Fisheries and Food, 1976). Similar analyses were also carried out on the finished diets (see Table III). Amino acid analysis was carried out on the POH (Table II) using a JEOL 6AM amino acid analyser. Hydrolysis of the samples was carried out by open flask re fluxing to 6 M HC1 for 24 h. Tryptophan was determined by the method of Miller (1967). Available lysine was determined by the method of Roach et al. (1967). TABLE II Amino acid composition of the poultry offal hydrolysate Amino acids

g 16 g-~ nitrogen

Amino acids

g 16 g-i nitrogen

Aspartic acid Threonine Serine Glutamic acid Proline Glycine Alanine Cystine Methionine

7.8 4.4 7.1 11.9 8.7 8.6 6.1 3.3 1.4

Isoteucine Leucine Tyro sine Phenylalanine Lysine Available lysine Histidine Arginine Tryptophan Valine

4.0 7.5 2.9 4.4 4.7 3.8 (80.9% available) 2.2 6.7 1.7 6.4

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Formulation and preparation o f diets Details of diet formulation and analysis are given in Tables III and IV. In the first experiment, 4 diets were computer-formulated to commercial broiler starter specifications so that in three of them, 6% of crude protein came from either fish meal (reference), POH in POHW or RM. In the fourth feed, 3% crude protein was supplied from POH in POHW. In the second experiment, broiler starter and finisher reference feeds were formulated in which fish meal contributed 6% of the feed dry matter. In the experimental feeds, POHW supplied 24 and 27.85%, respectively, o f the broiler starter and finisher feeds, and the POH provided 6.0 and 6.7% protein in the feed dry matter, respectively. In Experiment 3, feeds were again formulated to broiler starter and finisher specifications, so t h a t 6% of the crude protein in three o f the feeds came from fish meal (reference) POH in POHW, or POH which had been dried onto ground maize meal (POHM). In the fourth treatment, 6% crude protein was supplied by POH in POHW, but cassava was used as the carbohydrate source whilst maize meal was excluded. The POH has a high metabolizable energy content and to balance the energy c o n t e n t of feeds, high levels of wheat middlings were selected during formulation of the feeds using linear programming. Wheat middlings were also specifically included in the reference feed used in Experiment 1, in order that all feeds in this experiment should contain similar levels of this ingredient. In the other experiments, the wheat middlings shown in the formulation were chosen by linear programming alone.

Feeding trials In experiment 1, Ross day-old broiler chickens (60 males and 60 females) were housed in a Cope and Cope tier brooder and fed on a commercial broiler starter feed until 7 days of age. At this age, the chicks were wingtagged and weighed, and the 10 heaviest and lightest of each sex were removed. From the remaining 40 males and 40 females, groups of 20 chickens (10 males and 10 females) were assigned to each of the 4 treatments to give groups of similar weight-range. The chickens were fed on the experimental feed until 28 days of age, when half were killed for examination. Every second floor of the tier brooder was then removed to permit the remaining chickens to stay until 56 days of age, when t h e y were killed and the carcases eviscerated, weighed and skinned, and microbiologically examined for pathogenic bacteria. During the trial, individual weight of chickens was recorded at 7, 28 and 56 days of age, and group feed consumption at 28 and 56 days o f age. In Experiment 2, 100 Ross No. 1 day-old male chickens were randomly assigned in groups of 25 to 4 floor pens w i t h wood chippings as bedding. The fish meal reference and POHW feeds were given to duplicate groups

255 of chicks for 28 days. F o u r chickens from each pen were retained from Day 28 to Day 50 and fed on the broiler finisher feeds. Feed consumption and liveweight gain were recorded t h r o u g h o u t the experiment. The birds retained to 50 days were slaughtered and prepared as for the retail trade (New York dressed); dressing-out percentage and liver weight were recorded. Experiment 3 was carried o u t in a similar manner to Experiment 1, except that feeds used after 28 days of age were made to broiler finisher specifications and the carcases were prepared as for the retail trade. In all experiments the feeds were given as meals.

Statistical analyses Owing to limited facilities, replication was n o t possible in Experiments 1 and 3, but in Experiment 2, duplication of experimental treatments allowed a simple analysis of variance (Snedecor and Cochran, 1967) to be carried out on weight gains, carcase weights, dressing out percentages and liver weights. Standard errors of the means are shown for all parameters in all experiments. RESULTS Chemical analysis of POH shows it to be a good source of protein and also, because of its high fat content, a particularly good source of energy. Amino acid analysis shows it to be a good source of amino acids, especially the most c o m m o n l y limiting essential amino acids, lysine, methionine and cystine. These were present at 4.7, 1.4 and 3.3 g/16 g N, respectively. The lysine was 80.9% available. Bacteriological assessment of the POH and RM demonstrated the absence of Staphylococcus aureus, Clostridial and Salmonella species and Coliforms in these preparations. Estimations of total viable counts and total spore counts were within normal acceptable limits for animal feedstuffs. Broiler chicken weight gain, feed consumption, feed conversion efficiency and dressing-out percentage are given in Table V. The health of all chickens was good t h r o u g h o u t all experiments, post-mortem examination of carcases revealed no abnormalities, liver weights were normal and no potentially pathogenic bacteria were isolated from any of the carcases examined. In Experiment 2, no significant differences between treatments (P~0.05) were detected for weights gains, carcase weights, dressing-out percentages and liver weights. In Experiment 1, the weight gain and food conversion ratio o f chickens fed on the reference feed during the starter period were superior to those of chickens fed on the experimental feeds. Of the latter, those fed on the rendered meal had the worst performance and those fed on the high in-

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257 clusion of POH, the best. By the end of the experiment, this difference between treatments had greatly diminished, although the chickens fed on the rendered meal still had the poorest performance and those fed on the reference feed, the best. The improvement in performance of chickens fed on POH feeds during the finisher stage of growth when compared with their performance during the starter stage is more striking in Experiment 3 than Experiment 1. For the first 28 days, the gain of chickens fed on POH was approximately two-thirds t h a t of chickens fed on the reference feed. The former also had inferior food conversion ratios. However, by the end of the experiment, the differences in weight gain had largely disappeared and there was no difference between the food conversion ratios. DISCUSSION The performance of Ross chickens in these experiments was similar, or slightly inferior, to published performance targets for such chicks (Ross Poultry Great Britain Ltd., 1977). In Experiment 1, growth was poorer with feeds containing POH than with t h e fish meal reference feed, but better than with RM. The latter difference was probably due to the inclusion of feathers in the RM but not in the POH, and to the effect of heat processing reducing protein quality. There was no difference in performance of chickens fed on the fish meal reference feed and those fed on the POH feeds in Experiment 2, whilst in Experiment 3, the performance of chickens fed on feeds containing POH was inferior to those fed on the reference feeds. Little difference was n o t e d between treatments including P O H in Experiments 1 and 3. The greatest difference was between experiments and between the fish meal reference feeds and feeds containing POH. The difference between experiments was probably due to differences in the accommodation used, and possibly to variation in the food specifications used. Experiments I and 3 were carried out on wire floors and Experiment 2 on deep litter. The better over-all performance of chickens in Experiment 2 is explained by the fact that chickens reared on deep litter generally perform better than those on wire. The poorer performance of chickens in Experiment 3 during the first 28 days compared with those in Experiment 1 is difficult to explain, since the composition o f POH used in the two experiments was similar and all chickens received diets formulated to the same specification. However, by slaughter, the over-all gain and f o o d conversion ratio for both experiments were similar, even though a broiler starter specification was used t h r o u g h o u t Experiment 1. In Experiment 3, the feeds were formulated to a broiler finisher specification for use after 28 days. Owing to the high fat c o n t e n t and the high metabolizable energy (ME) value of POH, it was necessary to include large quantities of highly ab-

258 sorptive, low ME, wheat middlings in feeds containing POH. Unfortunately, one of the main c o m p o n e n t s of wheat middlings is wheat bran, which has a very p o o r nutritive value for chicks (Qazi and Netke, 1975). This is attributed to poor digestibility (Summers et al., 1968) and low metabolizability of the dry matter of the feed (Summers et al., 1969). Eastwood (1973) considered that this was due to the water-holding capacity o f wheat bran causing a more rapid transit of food through the gut and to its absorptive properties altering the availability of some nutrients. Wheat middlings also have a high volume, and Valdivie (1978) considered that the pelleting of feeds containing wheat middlings would favour the performance of chickens. This would eliminate its high volume, increase intake and avoid the separation of the ration mixture and food selection. During the early stages of these experiments, the chicks selected from the mixture provided, showing a preference for non-wheat middlings particles; the degree of selection depended on the particle size of the wheat middlings used. To the opposite extreme, the presence o f growth factors active in poultry digestion have been described in wheat bran (Hedge et al., 1978). Quite clearly, t h e importance of dietary fibre and the use of materials such as wheat middlings in the nutrition of poultry is poorly understood. It is therefore quite possible that some of the variation recorded in this series of experiments could be due to the use o f high levels of wheat middlings. Pelleting and crumbling diets, especially for use during the starter period, and the use of lower levels of wheat middlings would probably have improved the performance of chickens fed on the POH. However, with regard to application in developing countries, changes of this t y p e would probably n o t be practicable, since pelleting and crumbling facilities are rarely available and bulky materials such as wheat middlings are often the m o s t c o m m o n t y p e o f raw material available. Acid hydrolysis does not involve h e a t sterilization, which is required by law in m a n y countries before carcase wastes can be given to livestock. The application of this process in these countries would therefore be subject to local animal health legislation and requirements. It should also be n o t e d that in these studies, blood was n o t included with the other wastes and if available should form a useful addition to the mix. From the results of these experiments, it would a appear that poultry offal hydrolysate produced as described in this paper could have considerable potential as a feed ingredient for use in poultry feed, and merits further investigation. ACKNOWLEDGEMENTS The authors thank Mr. B. Francis and Mr. A. Quaraishi for assistance with analyses of ingredients and diets. Mr. A. Barranco and Miss J. Sutherland assisted with the care of experimental birds.

259 REFERENCES Disney, J.G. and Hoffman, A., 1976. A dried fish silage product. Proc. Torry Res, Stn. Symp. Fish Silage, Aberdeen, Scotland, Paper V, 14 pp. Disney, J.G,, Parr, W,H. and Morgan, D.J., 1978. Fish silage; preparation, utilization and prospects for development. Proc. IPFC, 18: 543--553. Eastwood, M.A., 1973. Vegetable fibre: its physical properties. Proc. Nutr. Soc., 32: 137--143. Francis, G.H. and Turnbull, A.T., 1979. The use o f formic acid-treated blood and broiler processing waste in the diet of finishing pigs. State Vet. J., 34(102): 210--215. Hedge, S.N., Rolls, B.A., Turvey, A. and Coates, M.E., 1978. The effects on chicks of dietary fibre from different sources: a growth factor in wheat bran. Br. J. Nutr., 40: 63--69. Lodhi, G.N., Daulat Singh and Ichhponani, J.S., 1976. Variation in nutrient content of feedingstuffs rich in protein and reassessment of the chemical method for metabolizable energy estimation for poultry. J. Agric. Sci., 86: 293--303. Machin, D.H., Hector, D.A., Swann, G. and Parr, W.H., 1983. Utilization of poultry offal hydrolysate as a feed for livestock in the tropics. Proc. Symp. Animals as Waste Converters, Wageningen, The Netherlands, November 1983. Miller, E.L., 1967. Determination of the t r y t o p h a n content of feedingstuffs with particular reference to cereals. J. Sci. F o o d Agric., 18: 381--385. Ministry of Agriculture, Fisheries and Food, 1976. The fertilisers and feeding stuffs (amendment) regulations. S t a t u t o r y Instrument No. 840, H.M.S.O., London, pp. 76. Qazi, A.M. and Netke, S.P., 1975. Studies on the improvement of nutritive value of wheat bran for growing chicks. Indian J. Anim. Sci., 45: 371--376. Roach, A.G., Sanderson, P. and Williams, D.R., 1967. Comparison of methods for the determination of available lysine value in animal and vegetable protein sources. J. Sci. F o o d Agric., 18: 274--278. Ross Poultry, 1977. Commercial Broiler Stock. Management Manual for the Commercial Ross 1 Broiler. Ross Poultry, Norwich, England, 25 pp. Snedecor, G.W. and Cochran, W.G., 1967. Statistical Methods. 6th Edn., Iowa State University Press, Ames, IA, 593 pp. Summers, J.D., Slinger, S.J., Pepper, W.F. and Moran, E.T., Jr., 1968. Biological evaluation of selected wheat fractions, from nine different wheat samples for energy and protein quality. Poult. Sci., 47: 1753--1760. Summers, J.D., Moran, E.T., Jr. and Pepper, W.F., 1969. Nitrogen digestibility of various selected reheat fractions. Can. J. Anita. Sci., 49: 105--112. Tatterson, I.N. and Windsor, M.L., 1974. Fish silage. J. Sci. F o o d Agric., 25: 369--379. Valdivie, M., 1978. Poultry production based on various feed products and by-products available in tropical climate countries. Cuban J. Agric. Sci., 12: 1--16.