Comparative nutritive value of Atella and industrial brewers grains in chicken starter ration in Ethiopia

Solomon Demeke

Jimma University College of Agriculture and Veterinary Medicine
 PO Box 307, Jimma, Ethiopia
solomon20089@yahoo.com

Abstract

Atella is a residue of home brewed beer in Ethiopia. The comparative nutritive values and protein qualities of Atella and Industrial Brewers Grains (BG) were studied using Noug  Seed Cake (NSC) protein as reference.Atella, BG and NSC were subjected to chemical analysis followed by feeding trials comprising of five treatments containing either Atella, BG, NSC, 50% Atella plus 50 % NSC or 50% BG plus50% NSC as a sole source of proteins using White leghorn baby chicks. Nutrient composition, body weight gain and Protein Efficiency Ratio (PER) were used as the major  evaluation parameters.

The results showed that both Atella and BG are low in dry matter and inferior to NSC in feed value for poultry as measured by cell wall contents. The crude protein content of the dry matter of Atella and BG are comparable (21% and, 24%). However, 6.23% of the proteins of Atella was heat damaged and nutritionally unavailable due to the effect of the traditional production method. Inclusion of Atella as the sole sources of protein in starters ration had significantly (P< 0.05) lower feed intake, weight gain and PER value than the others. There was improvement in the performance of the experimental chicks as a result of partial substitution of proteins of Atella and BG by NSC protein, indicating that NSC proteins supplement both the proteins of Atella and BG in starter ration.

Key Words: Fermentation residue, growth performance, protein quality, White leghorn

Introduction

In Ethiopia, availability and cost of feed is one of the major limitations to poultry production. This is true because of the fact that there is shortage of cereal grains, protein sources, vitamins and mineral supplements required to formulate balanced poultry rations. This situations warrants the evaluations of agricultural and agro-industrial by products and incorporation of suitable ones in to poultry rations. Some of the cereal grain by- products, particularly fermentation residues from alcoholic drinks and beverages are abundant in some parts of the country. The Ethiopian local beer by products Atella is produced in large amounts the year round. Currently small proportion of this by product is used as dairy cattle feed and large quantities accumulate at production sites causing disposal and public health problems.

The inclusion of the whole stillage as it is recovered from industrial distilling and brewing in to poultry ration, dates back to the 1930s. However, the increase in volume of production of the residues encouraged fractioning and drying of the stillage to facilitate storage, milling and shipping  (Vandepopulier 1981). Examinations of the production process of the residue raised the possibility that trace elements, B-complex vitamins, yeast metabolites or combinations of these may be responsible for some special dietary value of the dried stillage for poultry. Numerous elements including selenium compounds along with the proteins, vitamins and other trace minerals have been implicated on the intrinsic nutritional properties of these by products (Jensen et al 1974; Maurice and Jensen 1978; Underwood 1977; Jensen et al 1978; Eldred et al 1975). Unfortunately however, very little or nothing has been done in Ethiopia to determine the nutritional value of Atella for poultry. Although the principles of alcoholic fermentation remain the same, there seems to be difference in the nutritive value of Atella and industrial Brewers grains attributed to the difference in the raw materials and production methods used. The major objective of this research project was to study the comparative nutritive value and protein qualities of Atella and industrial Brewers grains in layers type starters ration in  Ethiopia.

Materials and methods

Atella collection and processing

This study was conducted at Jimma University, College of Agriculture and Veterinary Medicine after the raw materials and the traditional beer brewing method practiced by local beer makers in and in the vicinity of Jimma town were assessed. Based on the results of the assessment, adequate quantity of Atella used in the study was obtained on contractual basis. Adequate quantity of brewer's grains was also obtained from Bedele Brewery located at 140 km southwest of Jimma town. Both residues were sun dried, weighed pounded in local mortar, screened through a 0.33 cm sieve and stored until required for chemical analysis and feeding trials.

Laboratory chemical analysis

Representative samples of Atella, Brewers grains and Noug seed cake were milled to pass through 1mm screen. Sucrose and cooking oil were tested for nitrogen content while the other three were subjected to complete laboratory analysis. Dry matter, crude proteins, ether extracts and total ash  were determined according to the Proximate method of analysis (AOAC 1975). Neutral and acid detergent fibers, acid detergent fiber nitrogen and lignin were determined according to Goering and Van Soest (1970). Total digestible dry matter, total digestible nutrients and digestible and  metabolizable energies were estimated by employing regression and summative equation of Goering and Van Soest (1970) and NRC (1971).

Formulation of treatment rations

Five iso-caloric and iso-nitrogenous starter rations containing either Atella, Brewers grains, Noug seed cake, equal parts of Atella and Noug seed cake or equal parts of Brewers grains and Noug seed cake as the sole sources of proteins were formulated on the basis of laboratory analytical data (Table 1). Commercial premixes were offered for two consecutive days each week according to the recommendation of the manufacturer.

Management of the experimental animals

A total of 500 White leghorn day-old chicks were randomly divided in to 10 groups of 50 chicks each. Each group was separately transferred to electrically heated battery brooder and kept on standard starters ration for seven days. At an age of seven days, 250 chicks were randomly picked, weighed and numbered. The extremes of light and heavy  body weight were discarded and compensated from the remaining. The balance were  randomly divided into 10 groups each with 25 chicks and approximate average weight of  45 g/ chick. Finally the five treatment rations showed in Table 1 were randomized to the  experimental chicks in completely randomized design with 2 replicates for study period of 4 weeks.

Feed consumed and refused were recorded daily and the chicks were weighed  once a week. Mortality and any abnormality encountered were recorded throughout the the entire experimental period. Mean daily feed and protein consumption, body weight gain and protein efficiency ratio were the major parameters used to evaluate the difference between the treatments along with mortality and health condition of the experimental chicks. Finally all the data collected were subjected to statistical analysis.

Result and discussions

Chemical composition

The chemical composition of Atella, Brewers grains and Noug seed cake are shown in Table 2.

Atella and Brewers grains as recovered from the brewing process are comparable in percentage composition of dry matter (20-30%) and are difficult for storage and transportation. The percentage composition of total insoluble ash of Atella and Brewers grains were also comparable and lower than that of Noug seed cake. On the other side the ether extract content of both Atella and Brewers grains were higher than that of Noug seed cake, which seems to be attributable to the degree of extraction of oil from the Noug seed.

The percentage composition of cell wall components of Brewers grains was slightly higher than that of Atella possibly due to the higher fiber content of barley grain compared to that of maize grains used as source of starch for alcoholic fermentation during the production process of Brewers grains and Atella respectively. Lignin content and degree of lignifications was significantly higher for Atella. Since all the cell wall components are completely indigestible by poultry, there is no difference between Brewer's grains and Atella in nutritive value as measured by percentage composition of  NDF and ADF. Nougseed cake was found to be superior to both Atella and Brewers grains in nutritive value for poultry as measured by percentage  composition of NDF.

The crude protein content of the dry matter of Atella and Brewers grains was 22% and 24% respectively both values of which are lower than that of Noug seed cake (36%). Nevertheless protein content of both Atella and Brewers grains can be considered good by NRC (1971) standard suggesting that both residues could be used as protein supplement in poultry ration. However, 6.23% of Atella crude protein exists as ADF-nitrogen indicating that Brewers grains are superior to Atella in protein nutrition. The close examination of the traditional production process of Atella shows that excessive heat is applied during the preparation of raw materials used as source of starch for the alcoholic fermentations. The application of heat results in the production of nutritionally unavailable dark colored amino -sugar complex, caused by the combination of amino groups of proteins and aldehyde groups of carbohydrates (Maynard et al 1984). It has been considered that feed materials containing above 0.3% ADF-nitrogen possess a detrimental level of heat damage (Goering 1970). This cut off point is arbitrary and is substantially higher than the normal range for undamaged feeds (Van Soest 1983). In this study percentage composition of ADF-nitrogen of 0.996 (6.23% crude protein) was obtained from Atella indicating that the nutritionally available crude protein of Atella is about 15.6%.

The estimated total digestible dry matter and total digestible nutrient content of Atella (Table 2) were lower than that of Brewers grains and Noug seed Cake, which could be due to the relatively high crude fiber and heat damage protein content, which in turn lower the energy content of Atella. This is further evidenced by the low estimated digestible and metabolizable energy value of Atella as compared to that of Brewers grains and Noug seed cake.

Feed consumption

One of the principal factors determining nutritive value of feed is the quantity animals consume when they have access to it. The mean daily feed consumption of the experimental chicks are given in Table 3.

According to the results of this study, the use of Atella as the sole source of protein in starters ration resulted in significantly (P<0.05) lower feed consumption than the use of either Brewers grains or Noug seed cake as the sole source of proteins. Partial substitution of Atella by Noug seed cake positively affected feed consumption of the experimental chicks but failed to bring statistically significant (P>0.05) improvement over the use of Atella as a sole source of protein, where as partial substitution of Brewer grains by Noug seed cake brought significantly ( P<0.05) higher feed consumption over the use of Brewer grains as a sole source of protein. On the other side total substitution of either Atella or Brewers grains by Noug seed cake was found to be superior to all the others in mean daily feed consumption. The low feed  consumption of the groups fed on the treatments containing higher proportion of Atella is attributed to the higher fiber content and low digestibility of Atella compared to the others, since feed and nutrient consumption are positively correlated with digestibility. The low digestibility of Atella in turn seems to have had a negative effect on voluntary intake of the experimental chicks. The results of this study clearly showed that Noug seedcake is superior to both Atellaand Brewers grains and Brewers grains is superior to Atella in nutritive value as measured by mean daily feed consumption of the  experimental chicks.

Growth performance

The growth performance of the experimental chicks fed on the treatment rations containing Atella, Brewers grains and Noug seed cake as the sole source of proteins are shown in Table 3. Feeding of baby chicks with Atella, Brewers grains and Noug seed cake as the sole source of protein  brought mean daily body weight gain of 0.13, 0.35 and 1.11 g/head respectively, indicating that Brewers grains is superior to Atella and Noug seed cake is superior to Brewers grains in nutritive value as measured by chick growth performance. There was no significant difference between the groups fed on equal parts of Atella and Noug seed cake proteins and the groups fed on Brewers grains as the sole source of protein in mean daily body weight gain. The low growth performance of the experimental chicks fed on treatments containing higher proportion of Atella again seems to be attributed to low digestibility and low feed consumption.

Protein quality as measured by Protein Efficiency Ratio (PER) are also given in Table3. According to the results of this study, inclusion of Atella, Brewers grain and Noug seed cake as the sole source of protein in a starter ration brought PER value of 0.23, 0.37 and 0.69 respectively, again indicating that Noug seed cake is superior to the others in protein quality as measured by PER values followed by Brewers grains.

The nutritionally available protein content of Atella (15.6%) could satisfactorily contribute about 80% of the total crude protein requirement of baby chicks when adequately consumed and efficiently utilized. More over Atella, Brewers grains and Noug seed cake were included in to their respective treatment ration to contribute about 10% of available proteins. But since all proteins are not of equal value, their amino acid composition must be known to accurately to compare the nutritional value of proteins of Atella, Brewers grains and Noug seed cake in poultry ration. Although the  principles of alcoholic fermentation remain the same, there seems to be difference in protein and amino acid composition between Atella and industrial Brewers grains. The balance among the essential and the relation of the essential to the non-essential amino acids in Atella seems to be very low because of the excessive application of heat during the traditional production procedures of Atella which reduce the lysine, tryptophan, methionine and cystine as well as the biological value of proteins (Eggum 1973).

Lysine, methionine tryptophan, cystine and all the aromatic amino acids are regarded as the most heat sensitive amino acids (Van Soest 1983). Thus the low digestibility and the low essential amino acid content of Atella protein might had a negative effect on nitrogen retention nitrogen status and voluntary feed intake of the experimental chicks compared to that of Brewers grains proteins and amino acid composition. On the other side, according to Beyene (1976) with the exception of cystine and methionine the balance among the essential amino acids and the ratio of the essential to non-essential amino acids in Noug seed cake are very high. More over there were improvement in the production performance of the experimental chicks as a result of partial or total substitution of Atella and Brewers grain proteins by Noug seed cake proteins. There was no significant difference between equal parts of Atella and Noug seed cake, equal parts of Brewers grains and Noug seed cake and pure Noug seed cake proteins in PER values,  indicating that the protein quality of Noug seed cake is superior to that of Atella and Brewers grains. The result of this study is in agreement with that of Beyene (1976) and showed that there were improvements in the production performance of the experimental chicks as a result of partial or total substitution of Atella and Brewers grain proteins by Noug seed cake proteins. There was no significant difference between equal parts of Atella and Noug seed cake, equal parts of Brewers grains and Noug seed cake and pure Noug seed cake proteins in PER values, indicating that Noug seed cake protein supplements both Atella and Brewers grains proteins with certain essential amino acids in which they are deficient. .

Reference

AOAC 1975 Official method of analysis (12^th edition) Association of Official Analytical Chemist. Washington D.C

Beyene C 1976 Laboratory evaluation and estimation of nutritive value of some Ethiopian feed stuffs and formula feeds plus animal evaluation of Noug seed cake. PhD Thesis, Cornell University, Ithaca, New York.

Eggum B O 1973 A study of certain factors influencing protein utilization in rats and pigs. Publication 406. Institute of Animal Science. Copenhagen, Denmark.

Eldred A R, Damron B L and Harms R H 1974 Evaluation of brewers dried grain and yeast in laying hens diet containing various sulphur amino acid levels. Poultry Science 54: 856-860.

Goering H K and P J Van Soest 1970 Forage fiber analysis. Agri. Handbook No 397.

Jensen L S, Falen L and Change C H 1974 Effects of distillers dried grains with soluble on reproduction and liver fat accumulation in laying hens. Poultry Scienc53:586-592.

Jensen L S, Maurice D V and Murray M W 1978 Evidence for a new biological function of chromium. Feed Processing 37:404-410.

Maurice D V and Jensen L S 1978 Influence of diet composition of hepatic lipid accumulation and hemorrhage. Poultry Science 57;1690-1694.

Maynard L A, Loosli J K, Hintz H F and Warner R C 1984 Animal Nutrition (8^th edition). McGraw-Hill Book Company. Inc New York.USA.

National Research Council 1971 Nutrient requirement of poultry. NRC Publication .No5.

Underwood E J 1977 Trace element in human and animal nutrition (4^th edition). Academic Press, New York USA..

Vandepopulier M M 1981 Non ruminant nutritional use of gasohol production by-products. Feedstuffs 53:2.1

Van Soest P J 1983 Nutritional ecology of the ruminant. O and B Books Inc. USA

Received 24 October 2006; Accepted 30 October 2006; Published 1 January 2007

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