Nutritive value of rumen contents for monogastric animals

Animal Feed Science and Technology, 2 (1977) 351--360 351 © Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

NUTRITIVE VALUE OF RUMEN CONTENTS FOR MONOGASTRIC ANIMALS

MILOVAN JOVANOVI(~ and MARGITA ~UPERLOVIC

Institute for the Application of Nuclear Energy in Agriculture, Veterinary Medicine and Forestry, Ze mun-Beograd (Yugoslavia) (Received 4 February 1977)

ABSTRACT Jovanovid, M. and ~uperlovi6, M., 1977. Nutritive value of rumen contents for monogastric animals. Anim. Feed Sci. Technol., 2: 351--360. Rumen contents were investigated as a possible feed for farm animals. Although their composition varied to some extent, an average sample contained 21.8% crude protein, 30.3% crude fibre, 6.1% fat and 11.5% ash in the dry matter. Of total crude protein, 73.4% was amino acids. The raw rumen material was dried using the "organic carrier method" by previous mixing with maize meal (3 parts raw rumen contents/1 part maize meal). The product, RM meal (12.5% crude protein, 10.8% crude fibre, 5% fat, 4.9% ash), was used for feeding broiler chicks. The nutritive qualities of dried rumen contents (DRC) were assessed by biological tests on rats. Two levels of DRC (10% and 24%) were included in diets containing blood meal as a protein source and maize (Experiment I). The lower level of DRC (10%) did not reduce the growth rate of young rats (2.4 g/day), but the food consumption was increased. The total body composition of the rats was not changed (55.3% crude protein, 34.1% fat, 9.6% ash). The higher concentration of DRC decreased the growth rates markedly, as well as the apparent digestibility of dry matter and protein, and changed the body composition of rats. The apparent digestibility by rats of rumen protein in a semi-synthetic diet containing 50% DRC (Experiment II) was 44.6% and of dry matter, 56%. The RM meal was given to broiler chicks (0--8 weeks of age) as 23% or 60% of the diet which also contained soya bean meal, blood meal and sunflower meal as protein supplements (Experiment III). The chicks consumed all diets readily. The diet containing 23% RM meal (corresponding to 6.4% DRC) supported a better performance than the control diet. The larger amount of RM meal (corresponding to 17% DRC) reduced the final body weights of chicks.

INTRODUCTION I n t h e r u m e n n u t r i e n t s s u c h as c e l l u l o s e a n d n o n - p r o t e i n n i t r o g e n are c o n v e r t e d b y t h e m i c r o b e s i n t o m i c r o b i a l p r o t e i n , so t h a t t h e r u m e n a c t s as a n a t u r a l c o n t i n u o u s c u l t u r e s y s t e m f o r t h e p r o d u c t i o n o f s i n g l e cell p r o t e i n s . T h e q u a l i t y a n d b i o l o g i c a l v a l u e o f t h e m i c r o b i a l p r o t e i n s o b t a i n e d is s u c h that they may satisfy mest of ruminant requirements for proteins and amine acids.

352 The bulk amino acid composition of rumen bacterial population is fairly constant and independent of the type of ration given to the aninal (Weller, 1957; Meyer et al., 1967; Purser and Buechler, 1966; Hoogenraad and Hird, 1970; Czerkawski, 1976), although the overall nutritional quality can vary owing to differences in digestibility between various bacterial strains (Bergen et al., 1968a; Burris et al., 1974). The carbohydrate content of rumen bacteria and protozoa is markedly influenced by the type of diet and particularly by the time after feeding, as shown by Czerkawski (1976), while the variations in polysaccharide-free material are much smaller. The biological value to rats of microbial proteins from the rumen was found to be relatively high and the amino acid composition good; lysine and tryptophan concentrations were high, b u t sulphur-amino acids (Abdo et al., 1964) or histidine (Bergen et al., 1968b) were possibly limiting. Abdo et al. (1964) also emphasized the high concentrations of B-vitamins in the rumen liquor as a result of microbial ~ction. Besides the material of microbial origin, the rumen contains partially digested feed residues and this part of rumen contents may be considerably influenced by the type of diet and time interval between feeding and slaughtering. The practice at slaughter-houses to fast animals for 24 hours before slaughter and relatively standardised feeding of cattle on large farms diminish these effects. Moreover, by pooling large quantities of waste material before drying further unification will be achieved. Total rumen contents are much less often analysed than is rumen liquor. Some available data show that material collected at slaughter-houses contains 10--20% dry matter composed of: crude fibre (30--40%), crude protein (10-25%), fat (2--6%), N-free extract (38% or less) and ash (8--13%), according to Antongiovanni et al. (1973) and Jovanovi5 and ~uperlovic (1974). The digestibility of dry and organic matter is negatively correlated with crude fibre content (Antongiovanni et al., 1973). Some attempts have been made to dry rumen contents as collected at the slaughter-house and include them in diets for ruminants (Messersmith et al., 1974; Prokop et al., 1974) or poultry (Jarnicka-Postek et al., 1973). In practice, however, the contents of the rumen and abomasum are still regarded as useless waste products and considerable quantities are discarded. The isolation of protein from rumen contents, which will u n d o u b t e d l y be of much higher nutritional value than the whole material, would require costly technology. It is therefore of practical interest to investigate possibilities for more economic drying and better utilization of total rumen contents in animal nutrition. This work was done to determine the feasibility of incorporating total rumen contents in diets for monogastric animals. Nutritional effects of diets containing various proportions of dry rumen contents were determined in rats and chicks.

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MATERIAL AND METHODS Preparation o f r u m e n c o n t e n t s R u m e n c o n t e n t s were collected at the slaughter-house and dried in a c u r r e n t o f air at 50°C. When p r e p a r e d f o r feeding t o p o u l t r y , the raw material, containing 11.5% d r y m a t t e r , was m i x e d with maize meal (in the p r o p o r t i o n 3 : 1 ) b e f o r e drying, a c c o r d i n g to the so-called " o r g a n i c carrier m e t h o d " ( P . 1 6 6 4 / 7 6 ) . The w a t e r c o n t e n t o f the starting material was t h e r e b y r e d u c e d and the d r y i n g time c o n s i d e r a b l y s h o r t e n e d . The resulting d r y material was g r o u n d t o give r u m e n c o n t e n t - m a i z e meal (RM meal) c o n t a i n i n g a b o u t 28% dry rumen contents. The d r y r u m e n c o n t e n t s , maize meal used as carrier and the RM meal (Table I) were assayed f o r t o t a l n i t r o g e n b y the m i c r o Kjeldahl m e t h o d and for c r u d e fibre, c r u d e fat a n d ash b y s t a n d a r d m e t h o d s (JUS, 1963). A m i n o acid c o m p o s i t i o n was d e t e r m i n e d after acid h y d r o l y s i s using a B e c k m a n 1 2 0 B A m i n o Acid A n a l y s e r ( S p a c k m a n et al., 1958). TABLE I Analysis of dried rumen contents, rumen content-maize meal (RM meal) and maize meal Dried rumen contents Major components (g/l O0 g dry matter)

RM meal

Crude protein (N x 6.25) Crude fat Crude fibre Ash Total amino acids

12.5 5.0 10.8 4.9 10.6

9.0 3.9 1.7 1.5 9.0

7.7 4.5 4.8 17.0 6.3 4.8 6.7 1.9 5.5 2.9 4.0 10.6 3.8 4.7 6.0 2.9 4.8 1.1

6.5 3.8 4.9 18.3 8.7 4.0 7.5 2.4 5.3 2.2 3.9 11.9 4.1 5.0 3.1 2.8 4.8 0.7

21.8 6.1 30.3 11.5 16.0

Maize meal

Amino acid composition (g/l O0 g amino acids) Aspartic acid Threonine Serine Glutamic acid Proline Glycine Alanine Cystine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Lysine Histidine Arginine Tryptophan

11.0 5.7 4.5 15.5 4.7 5.3 6.0 0.8 5.5 1.3 4.3 9.0 3.5 4.5 8.8 2.8 4.8 2.0

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Feeding trials with rats. The nutritive value of rumen contents was investigated in two experiments with rats.

Experiment I. Male albino rats weighing 160+20 g were divided into three groups (10 animals in each) and fed on three experimental diets for 20 days. The animals were kept in pairs, their food consumption was measured, their body weights were determined and faeces were collected. The composition of the experimental diets is shown in the first part of Table II. In this and other feeding trials the protein supplement used in combination with dry rumen contents was blood meal, since it is also a slaughterhouse by-product. The control diet A contained only maize and dried blood, combined with mineral and vitamin supplements. Diets B and C contained 10% and 24% of dry rumen contents, respectively, with less maize and dried blood. All three diets were isonitrogenous, but the level of metabolizable energy (ME) was reduced by the incorporation of rumen contents. The values for ME shown in Table II, were obtained by calculation, the ME of rumen contents being assumed, from the data of Antongiovanni et al. (1973),to be 1Mcal/kg. At the end of experimental period the animals were killed with ether and autoclaved whole. After homogenization the concentrations of crude protein (N × 6.25), total lipids (Bligh and Dyer, 1959) and ash in the carcass were determined. Experiment II. This experiment was done in order to determine the apparent digestibility of dry matter and nitrogen in a diet containing rumen c o n t e n ~ as the sole protein source. The control semi-synthetic diet contained starch (54%), sucrose (20%), corn oil (5%), cellulose (4%), casein (12%) and mineral and vitamin supplements. The isonitrogenous experimental diet (10% crude protein) included 50% dried rumen contents in place of the casein and part of the starch. Chromic oxide (0.3%) was added to both diets. Rats weighing 100+10 g (six animals per treatment) received these two diets for six days. During the last three days faeces were collected, the nitrogen concentration of the diets and faeces was determined, and the apparent digestibility of crude protein was calculated as described by Varnish and Carpenter (1975). Experiment III. (Feeding trials with chicks). Sixty commercial broiler strain chicks (Hybro) were randomly allotted to three treatments at one day of age. They were kept in electrically heated battery brooders with raised wire floors. Ten chicks were housed in each c o m p a r t m e n t and each of the test diets was given to the chicks in two compartments. Food and water were supplied ad libitum.

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TABLE II Effects of feeding rats with diets containing dried rumen contents (Experiment I) Experimental groups A

B

C

Composition of diets (%) Maize meal Dried rumen contents Dried blood Mineral and vitamin suppl.a

84.3 -8.7 7

75.8 10 7.2 7

63.7 24 5.3 7

15.3 1.2 2.6 3.15

15.1 5.5 3.9 2.92

15.7 9.5 3.5 2.58

1.04 0.62 0.74 0.94 0.43 2.01 0.95 0.61 0.55

1.09 0.58 0.78 1.02 0.56 1.74 0.96 0.65 0.50

0.78 0.44 0.57 0.77 0.49 1.28 0.73 0.49 0.46

Analysis of diets (%) Crude protein (N × 6.25) Crude fibre Crude fat Metabolizable energy (Mcal/kg) Amino acids Lysine Histidine Threonine Valine Isoleucine Leucine Phenylalanine Tyrosine Methionine+cystine

Parameters of feed utilization Initial body weight (g) Mean daily weight gain (g) Mean daily food intake (g) Apparent digestibility (%) Crude protein Dry matter

+_4.02 b 159 2.1 +- 0.09 12.1

157 +-5.85 2.4 -+0.09 14.7

162 +-2.88 1.0 +-0.07 16.0

83.3 83.6

78.2 80.3

53.2 62.8

55.5 33.2 10.3

55.3 34.1 9.6

59.5 29.6 9.9

Total body composition (%) Crude protein Crude fat Ash a Veterinarski Zavod, Zemun. b SE of mean. T h e c o m p o s i t i o n o f t h e t e s t d i e t s is s h o w n i n T a b l e III. T h e c o n t r o l d i e t D contained standard protein nutrients (soya bean meal, sunflower meal, blood m e a l ) , w h i l e i n d i e t s E a n d F a p p r o x i m a t e l y 1 5 % a n d 30%, r e s p e c t i v e l y , o f t o t a l d i e t a r y c r u d e p r o t e i n was s u p p l i e d b y R M m e a l . D i e t D also c o n t a i n e d 2 5 . 4 % o f w h e a t b r a n , w h i c h was o m i t t e d f r o m d i e t s E a n d F i n o r d e r t o o b t a i n c o m p a r a t i v e levels o f c r u d e f i b r e a n d ME.

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TABLE III Results of feeding trials with chicks (Experiment III) Experimental groups D

E

F

Composition of diets (%) Maize meal RM meal Wheat bran Blood meal Soyabean meal Sunflower meal Mineral and vitamin suppl.a

41.6 -25.4 4 19 5 5

42.6 23 -4.4 20 5 5

8.1 60 -6.9 20 -5

22.3 5.0 2.4

22.1 4.9 2.6

22.3 7.5 2.5

Analysis of diets (%) Crude protein Crude fibre Metabolizable energy (Mcal/kg) Essential amino acids Threonine Valine Isoleucine Leucine Tyrosine Phenylalanine Lysine Histidine Arginine

0.92 1.27 0.78 2.09 0.66 1.20 1.18 0.75 1.33

1.02 1.18 0.68 1.92 0.58 1.15 1.25 0.69 1.25

1.06 1.51 0.70 2.43 0.82 1.25 1.50 0.78 1.25

Results of feeding Initial body weight (g) Final body weight(g) Average daily gain (g) Feed efficiency (g/g)

41 -+0.7b 1620 +-52.9 28.2 2.9

42 -+0.7 1723 -+47.7 30.0 2.9

39 -+0.8 1498 +-32.8 26.1 3.0

a Veterinarski Zavod, Zemun. b SE of mean.

A f t e r 6 w e e k s o f age t h e level o f s o y a b e a n m e a l was r e d u c e d i n all t h r e e d i e t s a n d t h a t o f m a i z e i n c r e a s e d , so t h a t t h e c r u d e p r o t e i n level was a d j u s t e d t o 20%. T h e w h o l e f e e d i n g t r i a l l a s t e d 8 w e e k s . D u r i n g t h a t t i m e i n t e r v a l t h e body weights of chicks and food consumption were recorded. The concent r a t i o n o f c r u d e p r o t e i n , c r u d e f i b r e a n d a m i n o a c i d s i n d i e t s D, E a n d F w e r e a n a l y s e d as b e f o r e .

357 RESULTS AND DISCUSSION

Experiments with rats The rumen contents used in feeding trials with rats (Table I) contained 21.8% crude protein of which 73% was amino acids. The concentration of crude fibre (30.3%) was lower than the value determined by Antongiovanni et al. (1973) but the level of crude fat was higher. Therefore, it can be assumed that the ME content of our material was higher than the value given by Antongiovanni (0.88 Mcal/kg for total rumen content and 1.127--1.635 Mcal/kg for filtered contents dried by different procedures}. Nevertheless, it was undoubtedly lower than the ME of the blood meal and maize replaced by rumen contents in diets B and C, which led to the lower energetic value of these diets. Amino acid composition of the three experimental diets is shown in Table II. The replacement of blood proteins by rumen proteins was followed, by a reduction in basic amino acids and leucine (which are exceptionally high in blood meal} and an increase in isoleucine concentration, since it is the first limiting amino acid of blood meal. The growth rate of rats given diet B was faster than that of the control group A. The relatively lower digestibility and lower energy of diet B was compensated for by the higher food consumption. In group C, however, this was not possible and the rats grew significantly more slowly despite an increased food consumption. The apparent digestibility of the dietary protein in this group was only 53.2% and that of dry matter, 62.8%. The group C animals were leaner, containing relatively more crude protein and less crude fat than the animals from groups A and B. In Experiment II the apparent digestibility of protein was 44.6% when the protein originated from dry rumen contents, 82% with casein as the protein supplement. The apparent digestibility of the total dietary dry matter was 56% and 88% for the two diets, respectively. These experiments have shown t h a t moderate amounts of whole dried rumen contents (eg. 10% rumen material combined with 7.2% dried blood) included in the diet of rats give good results. Higher concentrations of dried rumen contents in the diet were in our case followed by a reduction in the ~ o w t h rate and performance of young rats. This effect can be explained by: (a) the high level of crude fibre in rumen contents and lower ME of diets containing this material, or (b) poorer utilization of microbial proteins by rats. The biological value to rats of rumen microbial proteins was found to be relatively high (Bergen et al., 1968), so that the first point is the more probable explanation for lower utilization of this material.

358

Experiment with chicks Rumen contents were given to poultry as RM meal (containing approximately 28% dry rumen contents) combined with blood meal (Table III). Wheat bran was used to give approximately equal levels of crude fibre and ME in the diets, but the ME content was lower than National Research Council (1973) recommendations. Relatively small proportions of dietary protein originated in diets E and F from rumen contents (approximately 6.5% and 17%, respectively). The amino acid composition of the protein complex showed slight inbalance between leucine and isoleucine in all diets, as a consequence of the leucine/isoleucine ratio in blood meal, which supplied 16% of total protein in diet D, 18% in diet E and 27% in diet F. The chicks consumed all three diets readily during the whole feeding period (0--8 weeks of age). Diet E, containing about 6.5% of dry rumen contents and 4.4% of dry blood, supported a better growth rate than the control diet D. Diet F, with a higher percentage of dried slaughter-house byproducts gave a lower final body weight. In this experiment rumen contents were used rather cautiously, since they provided a very unconventional supplement for broiler feeding. They were given with blood meal in order to utilize these two by-products together as they are obtained at slaughter-houses. The results were encouraging, indicating that dry rumen contents (prepared as RM meal) can be utilized in broiler feeding, at least in the proportions used in this experiment. Higher percentages of rumen contents would require the incorporation of a high° energy supplement (such as corn oil or fat) in diets to balance the relatively low ME value of rnmen contents. Some methodical comments and conclusions The procedure used for drying rumen contents in these investigations offers a number of advantages. Premixing the raw material with maize meal considerably reduced the initial moisture content and the product provided a greater surface to the air current. Drying was then faster with a smaller expenditure of energy. This is particularly important since the cost of drying is the first factor which might limit wider utilization of slaughter-house byproducts. Moreover, the material obtained (RM meal) was suitable for direct incorporation into diets. Maize enriched with rumen contents contained more crude protein and relatively more lysine in the protein than maize alone. On the other side, maize improves the energetic value of rumen contents and facilitates their utilization in feeds for monogastric animals. The main limitation for more extensive use of rumen contents in the nutrition of pigs or poultry remains the physiological incapability of these species to digest cell wall carbohydrates. Although some cellulose and hemicellulose digestion takes place in the intestine of pigs (Keys and DeBarthe, 1974) or rats (Yang et al., 1969) the extent of total fibre utilization is rela-

359

tively small. The protein quality of rumen microflora, however, is nutritionally very advantageous because of high concentrations of lysine, tryptophan and some other essential amino acids. This is particularly important in broiler feeding, where demands for these amino acids are very high. For instance, the supplementation of broiler diets with 10% dry rumen contents (or a b o u t 35% RM meal) would supply about 10% of broiler protein requirements, about 12% of the total lysine required and 15% of the tryptophan. Experiments with rats show that this percentage of rumen material is quite acceptable and it can be assumed that this would be a convenient level of rumen contents in broiler feeding also. The supplementation of diets with rumen contents has some additional benefits, such as the enrichment of diets with B-vitamins, b u t such aspects are not y e t sufficiently investigated. Because of the vast quantities of rumen contents which are produced (and discarded} at slaughter-houses, their efficient utilization in broiler feeding could have an important economic effect by giving this by-product a monetary value and by supplying more proteins for poultry feeding.

REFERENCES Abdo, K.M., King, K.W. and Engel, R.W., 1964. Protein quality of rumen microorganisms. J. Anim. Sci., 23: 734--736. Antongiovanni, M., Giorgetti, A. and Poli, B.M., 1973. Valore nutritivo del contenuto ruminale disidrato. Aliment. Anim., 17: 47--54. Bergen, W.G., Purser, D.B. and Cline, J.H., 1967. Enzymatic determination of protein quality of individual rumen bacteria. J. Nutr., 92: 351--364. Bergen, W.G., Purser, D.B. and Cline, J.H., 1968a. Effects of rations on the nutritive quality of rumen microbial protein. J. Anim. Sci., 27: 1497--1501. Bergen, W.G., Purser, D.B. and Cline, J.H., 1968b. Determination of limiting amino acids of rumen-isolated microbial proteins fed to rat. J. Dairy Sci., 51 : 1698--1700. Bligh, E.G. and Dyer, W.J., 1959. A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol., 37: 911--915. Burris, W.R. Bradley, N.W. and Boling, J.A., 1974. Amino acid availability of isolated rumen microbes as affected by protein supplement. J. Anita. Sci., 38: 200--206. Czerkawski, J.W., 1976. Chemical composition of microbial matter in the rumen. J. Sci. Food Agric., 27: 621--632. Hoogenraad, N.J. and Hird, F.J.R., 1970. The chemical composition of rumen bacteria and cell walls from rumen bacteria. Br. J. Nutr., 24: 119--127. Jarnicka-Postek, M., Lukasiewicz, W., Gwara, T. and Mazanowska, A., 1973. Pr6ba zastosowania tregci ~.wacza w tywieniu Kurczat. Zesz. Nauk. Akad. Roln. Wroclawiu, Zootech. 104: 175--184. Jovanovid, M. and ~uperlovid, M., 1974. Mogudnosti korisdenja nekih klanicnih otpadaka u ishrani ~ivotinja. Krmiva (Zagreb), XVI: 241--246. JUS, 1963. Jugoslav Standard Methods, JUS E. Al. 022--026. Slu~.beni List SFRJ, 35 (1.X.1963). Keys, J.E. and DeBarthe, V., 1974. Cellulose and hemicellulose digestibility in the stomach, small intestine and large intestine of swine. J. Anita. Sci., 39: 53--56. Messersmith, T.L., Fulton, W.R. and Klopfenstein, T.J., 1974. Dried paunch feed as a roughage source in beef finishing rations. J. Anita. Sci., 3 9 : 2 4 6 (Abstr.).

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Meyer, R.M. Bartley, E.E., Deyoe, C.W. and Colenbrander, V.F., 1967. Feed processing. 1. Ration effects on rumen microbial synthesis and amino acid composition. J. Dairy Sci., 50: 1327--1332. National Research Council, 1973. Nutrient Requirements of Poultry. Seventh revised edition. National Academy of Science, U.S.A. Prokop, M.J., Klopfenstein, T.J. and Messersmith, T., 1974. Blood and paunch meal in ruminant rations. J. Anim. Sci., 3 9 : 2 5 0 (Abstr.). Purser, D.B. and Buechler, S:M., 1966. Amino acid composition of rumen organisms. J. Dairy Sci., 49: 81--84. Spackman, D.H., Stein, W.H. and Moore, S., 1958. Automated recording apparatus for use in the chromatography of amino acids. Anal. Chem., 30: 1190--1206. Varnish, S.A. and Carpenter, K.J., 1975. Mechanisms of heat damage in proteins. 6. The digestibility of individual amino acids in heated and propionylated protein. Br. J. Nutr., 34: 339--349. Weller, R.A., 1957. The amino acid composition of hydrolysates of microbial preparations from the rumen of sheep. Aust. J. Biol. Sci., 10: 384--389. Yang, M.G., Manoharan, K. and Young, A.K., 1969. Influence and degradation of dietary cellulose in the caecum of rats. J. Nutr., 97: 260--266.