Acacia nilotica, Acacia seyal and Sesbania sesban as supplements to tef (Eragrostis tef) straw fed to sheep and goats

ELSEVIER

Small Ruminant Research 18 ( 1995) 233-238

Acacia nilotica, Acacia seyal and Sesbania sesban as supplements to tef (Eragrostis tef) straw fed to sheep and goats C. Ebong Natnulonge Agricultural

and Animal Production Research Institute, P.O. Box 7084, Kaqmla, Accepted

Uganda

18September I994

Abstract Fifteen sheep and 15 goats were fed isonitrogenous amounts (7.2g N day-‘) of A. nilotica, A. seyd and S. sesbun as supplements to ad libitum allowance of tef straw in a randomized block design. Sheep consumed more straw and total DM than goats fed on the same browses. Digestibility of DM and NDF were higher (P <0.05) in goats than in sheep. Differences between browse species in intake of straw were not observed; however apparent N digestibility, rumen ammonia, and N retention were consistently lower in animals fed A. seyal than when animals were fed A. nilotica and S. sesban. It was concluded that differences in intake between sheep and goats could be attributed to differences in retention times and hence digestibility of DM and NDF. Differences between browse species are attributed to types and levels of tannin and related polyphenols in the leaves; and their effect on N metabolism in the rumen. Use of the faecal N fractionating technique as a non-invasive method of determining N degradability in ruminants may not be applicable to high tannin feeds. Keyword.s: Acacia; Tannin; Straw: Sheep; Goats

1. Introduction

Cereal straws and leguminous tree species are valuable feed resources for ruminant livestock in developing countries. The straws are usually deficient in protein, vitamins and critical minerals. The converse is true in the leaves of most browse species (Le Houerou, 1980). However most contain tannin and related polyphenols (Reed, 1986; Glyphis and Puttick, 1988). These compounds are astringent (Bate-Smith, 1973)) inhibit intake (Donnelly, 1954) and reduce digestibility (Donnelly and Anthony, 1969). In ruminants, tannin have beneficial effects, protecting proteins from degradation by rumen microorganisms and promoting the utilization of endogenous N in the rumen (Barry and Manley, 1984). This improves the amount and quality of post-ruminal amino acid 0921~4488/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSD10921~4488(95)00676~1

absorption (Waghorn et al., 1987). The balance between adverse and beneficial effects is likely to vary with species of plant materials and animals. This study was undertaken to examine effects of tannin in three browse species (A. seyal, A. nilotica and S. sesban) on intake, digestibility and N metabolism in the rumen and its excretion patterns in urine and faeces of sheep and goats.

2. Materials

and methods

Animals used were randomly selected from those in a growth trial for 90 days (C. Ebong, unpublished data, 1990). They had been fed isonitrogenous amounts (7.2g N day- ’ ) of the three browse species (A. nilotica and S. sesban) as supplements to ad libitum tef (E. tefl

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C. Ebong /Small Ruminant Research 18 (1995) 233-238

straw. Five animals from each treatment group were randomly selected and confined individually in metabolic cages. They were fitted with urine collection funnels and maintained on the same dietary treatments used during the growth trial. Ten days were allowed for adaptation to the harnesses. Thereafter collection and measurements of daily faeces and urine outputs were undertaken for 9 days. Urine was recovered and preserved in bottles containing 5 ml of 12N H2S04. Faeces were recovered in metallic basins placed underneath the cages. During the collection period, daily feed offered and refused were weighed. Samples (5%) of daily outputs of faeces and urine from each animal were bulked across the 9 days of collection. Urine and faeces were kept at 4°C and - 2O”C, respectively, for subsequent analysis. On day 10 of collection the harnesses were removed, animals were retained in the cages on the same dietary treatments. Rumen fluid was taken from each animal immediately before feeding (0 h) and 2, 4 and 9 h subsequently using a stomach tube inserted through the oesophagus into the.reticulo-rumen. For preservation 2 ml of 12N sulphuric acid was added immediately. Portions (5 ml) of rumen fluid from the same animals were bulked across the sampling times and stored at 4°C for subsequent analysis. 2. I. Laboratory analysis Samples of feed offered or refused and of faeces were analysed for contents of DM according to AOAC ( 1980). NDF and ADF were analyzed as described by Goering and Van Soest ( 1970) ; while N was analyzed Table 1 Composition

of the feeds used (g kg-’

Components

(AbsS50nm g-’ NDF)

2.2. Data analysis Intake was calculated as the difference between offers and refusals corrected for DM contents of the respective feed components. Digestibility was calculated as the proportion of the ingested feed components that was not recovered in the faeces. N retention was calculated as the amount ingested less the amounts excreted in the faeces and urine. Data were analyzed by General Linear Model on SAS Inc. statistical package available to the International Livestock Centre for Africa (ILCA), Addis Ababa, Ethiopia.

3. Results and discussions Palatability of leguminous fodder species is associated with contents of condensed tannin (Jones et al., 1976). The contents of insoluble proanthocyanidins (Table 1) and the gelatin precipitating properties of the three browses (Reed et al., 1985) suggested that A. seyal would be more astringent and less readily consumed than A. nilotica and S. sesban. The converse was observed in this experiment, and no difference in acceptability of the three browses was apparent. How-

DM) Eragrostis

tef DM OM N NDF ADF Lignin Soluble phenolics Insoluble proanthocyanidins

by micro-Kjeldhal procedure (AOAC, 1980). Soluble phenolics and insoluble proanthocyanidins were extracted and assayed according to Reed et al. ( 1985). Samples of urine were analyzed for N, rumen fluid samples for ammonia N by steam distillation into boric acid and back titration with O.lN HCl (AOAC, 1980) ; and concentration of various volatile fatty acids (VFA) by Gas Liquid Chromatography (GLC) .

929 853 5.5 715 406 54

Acacia nilotica

Acacia se.val

Sesbania sesban

923 855 25.1 179 104 39 338

929 843 27.8 261 133 48 295

920 796 48.1 168 111 24 157

21.3

39.8

11.0

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Ruminant Research 18 (1995) 233-238

235

Table 2 Intake (g per kg’.“) and digestibility (g kg-’ intake) in sheep and goats fed tef (Eragrostis tef, straw in combination with isonitrogenous (7.2g N day-‘) amounts of A. nilotica, A. seyal and S. sesban Browse

Goats A. nilotica

Straw intake Total DMI Digestibility DM OM NDF Digestible DMI

Sheep A. seyal

36.2 a 60.4 b

40.7 b 64.7 c

643’ 639 ’ 527 a.b 38.8 b

606 b.C 594 b.C 517 a.b 39.3 b

S. sesban

37.7 a.b 55.5 a 551 a 541* 488 a 30.6 a

A. nilotica

SEM A. seyal

S. sesban

43.7 b 70.2 d

43.1 b 69.3 d

51.6’ 69.0 d

1.61 1.53

589 a,b 576 a,b 494 a.b 41.4 b

569 a 544” 494 a.b 37.6 b

552 a 544” 562 b 38.1 b

1.20 2.40 1.70 3.50

a.b.c.dValues with the same letters in a row are not different (P> 0.05)

ever goats fed S. sesban took 2-3 weeks longer to adapt and finish the browse allowance. A. seyal leaves may have lost astringency due to reduced contents of tannin during drying (Ahn et al., 1989). Similarly, A. nilotica contains hydrolysable tannin (Self et al., 1986)) which has been implicated in gallic acid poisoning (Kumar and Singh, 1988). However no toxic effects were observed in sheep and goats used in this experiment. Under grazing conditions goats consume more browse than sheep (Harrington, 1986). In this experiment no difference between these animals in browse preference was observed. Hence browse intake was assumed to have little contribution to difference in total DMI between sheep and goats. There was also no consistent effect of browse on intake of straw. Sheep consumed more straw (P 0.05) (Table 2). This observation is contrary to findings of Alam et al. (1983; 1985) and pertains to situations where selective feeding habits of goats have been suppressed (Owen and Aboud, 1987; Pfister and Malechek, 1986). This was achieved by fine ( l-2 cm) chopping of tef straw before feeding. In animals fed acacias, the difference in total DMI between sheep and goats could be attributed to longer retention times in goats than in sheep (Alam et al., 1985). This contention is corroborated by higher DM and NDF digestibility in goats than in sheep fed A. nilotica and A. seyal. High intakes of straw and total DMI by sheep fed S. sesban than goats fed on the same browse reflect the difference in NDF digestibility between the two species. The reason for reduced NDF digestibility in goats fed S. sesban is not known.

Because of low contents of N in straw (Table 1) the differences in straw intake (Table 2) did not contribute significantly to N intake (Table 3). Faecal N output (grams per day) did not differ between animal species except when sheep and goats fed S. sesban were compared. However N excretion in faeces differed between browses (P < 0.01). In this respect sheep and goats fed A. seyal voided more N in faeces than respective animals fed A. nilotica and S. sesban. Consequently apparent N digestibility was 16.0-22.8% lower in animals fed A. seyal than those fed A. nilotica and S. sesban. A similar pattern was observed in urinary N excretion and N retention, where proportionately less N was excreted or retained in urine and tissues, respectively, in animals fed S. seyal than in those fed A. nilotica and S. sesban (P
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Ruminant Research 18 (I995) 233-238

Table 3 Nitrogen intake (g d-l), excretion (g dd ‘; and proportions of intake) pattern in faeces and urine, and retention in the body in sheep and goats fed tef (Eragrosris tef) straw in combination with isonitrogenous (7.2g N day - ‘) amounts of A. nilotica, A. seyal and 5. sesban Browse

Goats

Sheep

A. nilotica Intake Faecal excretion Apparent dig. (g Faecal NDFN (g (% N intake) Faecal NDSN (g (% N intake) Urine (g d-l) (% N intake) N retention (g d-

8.2 3.2 661 d 0.6 5.8 2.7 28.1 3.2 35.2 1.7

kg- ’ ) dd’) dd’)

‘)

a a a a a ’ b,C

A. seyal

S. sesban

9.0

9.8

5.0 b 441 a.b 1.3’ 14.4 d 3.7 b 41.0 b 2.3 a.b 25.2 = 1.7

3.1 688 d 0.6 5.6 2.5 25.6 4.0 40.3 2.6

A. nilotica

a a ’ = a d c

SEM A. seyal

9.3

9.1

3.9 a 582 =J 0.8 b 8.6 = 3.1 a 33.3 s.b 2.8 b.c 29.8 b 2.6

5.9 b 354 a 1.6’ 17.6 d 4.3 b.c 47.9 c 1.6a 18.1 = 1.6

S. sesban 10.7 5

,$ 0.6 6.1 4.6 42.5 3.2 30.1 2.3

’ b.C ’ b

0.4 0.4 5.2 0.08 1.05 0.4 4.7 0.3 4.1 1.4

NDFN, tibre bound N, neutral detergent soluble N. a.h.c~dValues with the same letters do not differ (P > 0.05).

The increase in faecal NDSN in ruminants fed tannin containing feeds therefore suggests that polyphenols in browse materials promote microbial growth in the rumen. This either negates the evidence of tannin-protein protection in the rumen (Jones and Mangan, 1977; Waghorn et al., 1987); or suggests that the use of NDS fractionation method is inappropriate for accessing protein degradability of tropical browses and tannin containing feeds. The corollary of this conclusion is that NDSN is primarily indigestibleN in feed. This situation pertains when hydrophobic predominate over hydrogen bonding in the formation of tannin-protein complexes (McManus et al., 1981; 1985). Concentrations of ammonia in rumen fluids differed between species of animals (P
Concentrations in rumen fluids obtained from goats were 72, 78 and 65% higher than observed in rumen fluids from sheep when animals fed on A. nilorica, A. seyal and S. sesban, respectively, were compared (Table 4). Comparison within species shows that the concentration of ammonia were lower (by > 70%) in rumen fluids obtained from animals fed A. seyal than in those from animals fed A. nilotica and S. sesban. The observation indicated that microbial growth and deamination was inhibited by tannin in A. seyal (Jones and Mangan, 1977; Waghorn et al., 1987). Nevertheless microbial growth in the rumen could be sustained on endogenous N recycling in the rumen. The latter phenomenon partially explains lower urinary N excretion in animals fed A. seyal (Table 3) and the progressive increments of duodenal non-ammoniaN flows that

Table 4 Concentrations of ammonia (mg loo-‘) and VFA components in rumen fluids of sheep and goats fed isonitrogenous A. seyal and S. sesban as supplements to ad libitum tef (Eragrostis tef) straw Browse

Ammonia Total VFA Acetate Propionate Isobutyrate Butyrate Isovalerate Valerate

Goats

amounts of A. nilotica,

SEM

Sheep

A. nilotica

A. seyal

S. sesban

A. nilotica

A. seval

S. sesban

22.0 = 81.5 b 66.0 h 9.8 a 0.25 ’ 4.8 ‘X 0.39 b 0.29 a

12.8 b 67.7 a 53.7 R 9.5 B 0.13” 3.8 a 0.17 a 0.30 =

20.8 ’ 89.7 ‘/.I 68.1 b 14.7 c 0.42 ’ 5.3 c 0.53 c 0.55 c

12.8 b 89.0 c.d 71.4 b.c 11.5b 0.19 b 5.1 c 0.40 b 0.29 ’

8;:: :,c 68.1 b 10.5 Lb 0.13 a 4.1 a 0.15 = 0.29 a

12.6 b 95.1 d 73.2 b.c 14.9 = 0.41 d 5.3 = 0.54 = 0.44 b

a.h.cValues with the same letters are not different (P > 0.05).

1.8 3.3 2.7 0.6 0.02 0.3 0.04 0.03

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Ruminant Research 18 (1995) 233-238

could be expected with increasing levels of dietary tannin (Barry and Manley, 1984). One of the reasons often advanced for better utilization of fibrous crop residues by goats than sheep is the ability to concentrate ammonia N in the rumen (Alam et al., 1985). This phenomenon is associated with higher concentrations of urea in saliva of goats compared with sheep (Seth et al., 1976). Differences in concentrations of rumen ammonia between sheep and goats (Table 4) were possibly enhanced by higher DMI in sheep (Table 2)) which provided more energy for microbial growth in the rumen. This is consistent with higher VFA concentrations in rumen fluids of sheep than those from goats (P < 0.05) (Table 4). Lower concentrations of ammonia N in rumen fluids from animals fed A. seyal, compared to those obtained from animals fed on the other browse, was associated with higher concentrations of isobutyrate and isovalerate (Table 4). These VFAs are deamination products of leucine and valine, respectively. The contribution of endogenous N to rumen ammonia notwithstanding, this observation suggested that protein in A. seyal was less degradable in the rumen than protein in A. nilotica and S. sesban. The differences in degradability can be attributed to differences in types and levels of tannin and related polyphenols in the browses. The study underscores the role of tannin in protein nutrition of ruminants and the need for further understanding of the physiological and biochemical mechanisms involved.

Acknowledgement This study was sponsored by the International Livestock Centre for Africa (ILCA) as part of the Graduate Associateship Programme. The author is grateful to Dr. Scholten, J.D. Reed, and J.H. Topps, who facilitated and guided the study. The editorial comments of J. Ogwang and B. Khizza were useful in writing the paper.

References Ahn, J.O., Robertson, B.M., Elliot, R., Gutteridge, R.C. and Ford, C.W., 1989. Quality assessment of tropical browse legumes: Tannin content and protein degradability. Anim. Feed. Sci. Technol. 27: 147-156.

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Alam, M.R., Poppi, D.P. and Syke, A.R., 1983. Intake, digestibility and retention times of 2 forages by kids and lambs. Proc. 2nd. Symp. N. Z. Sot. Anim. Prod.,43: 119-121. Alam, M.R., Poppi, D.P. and Syke, A.R., 1985. Comparative intakes of digestible organic matter and water by sheep and goats. Proc. N. Z. Sot. Anim. Prod., 45: 107-l 11. AOAC., 1980. Official Methods of Analysis. 13th edn. Assoc. Off, Anal. Chem., Washington, DC. Barry, T.N. and Manley, T.R., 1984. The role of condensed tannins in the nutritional value of Lorus pendunculntus for sheep: 2. Quantitative digestion of carbohydrates and proteins. Bri. J. Nutr., 5 1: 493-504. Bate-Smith, E.C., 1973. Haemanalysis of tannins: the concept of relative astringency. Phytochem., 12: 907-912. Dinius, D.A., Lyon, C.K. and Walker, A.G., 1974. Evaluation of protein sunflower oil complex treated with formaledhyde. J. Anim. Sci., 38: 467-474. Donnelly, E.D., 1954. Some factors that affect palatability in Serecea lespedeza L. cunneata. Crop Sci., 46: 90-91. Donnelly, E.D. and Anthony, W.B., 1969. Relationship of tannin, dry matter digestibility and crude protein in Serecea lespedeza. Crop Sci., 9: 361-362. Ehohe, O.W., Thereza, Y.M., Buvendra, U. and Adu., I.F., 1983. The nutritive value of tannin-treated cotton seed cake for growing lambs. J. Anim. Prod. Res., 3: 15-25. Glyphis, J.P. and Puttick, G.M., 1988. Phenols in some Southern African Mediterranean shrubland plants. Phytochem, 27: 743751. Goering, H.K. and Van Soest, P.J., 1970. Forage fibre analysis (apparatus, reagents, procedures and some applications) Agricultural Handbook No. 379, Agric. Res. Serv.. USDA, Washington, DC, pp. l-8. Harrington, G.N., 1986. Herbivore diets in semi-arid Eucal.vptus poplar woodlands. Aust. J. Exp. Agric., 26: 426-429. Jones, W.T., Broadhurst, R.B. and Lyttleton, J.W., 1976. The condensed tannins of pasture legume species. Phytochem., 15: 14071412. Jones, W.T. and Mangan, J.L., 1977. Complexes of tannins in sainfoin (Onobpchus uiuiifolia) with fraction 1 protein and submaxillary mucoprotein and their reversal by polyethylene glycol at low pH. J. Sci. of Food and Agric., 28: 126-136. Kumar, R. and Singh, M., 1988. Tannins: their adverse role in ruminant nutrition. J. Agric. and Food. Chem., 32: 447-453. Le Houerou, H.N., 1980. Chemical composition and nutritive value of browse in tropical West Africa. In: le H.N. Houerou (Editor). Browse in Africa: The current state of knowledge. ILCA. Addis Ababa, 1989, pp. 261-289. Mason, V.C., 1969. Some observations on the distribution and origin of N in sheep faeces. J. Agric. Sci. Camb., 73: 99-l 11. Mason, V.C. and White., 1971. The digestion of baceterial mucopeptide constituents in sheep 1. metabolism of 2, 6 diaminopimelic acid. J. Agric. Sci. Camb., 77: 91-98. Mason, V.C., 1981, Factors influencing faecal N excretion in sheep. 1. digestibility and level of intake of pelleted diets. Z. fur Tierphysiol. und Futtermittelkd. 45: 161-173. McManus, J.P., Davis, K.G., Lilley, T.H. and Haslam, E., 1981. The association of proteins with polyphenols. J. Chem. Sot. (Chemical. Communications) 309-311.

238

C. Ebong /Small Ruminant Research 18 (1995) 233-238

McManus, J.P., Davis, K.G., Bearte, J.E., Gaffney, S.H.,Lilley,T.H. and Haslam, E., 1985. Polyphenols interactions. Part 1. Introduction: Some observations on the reversible complexation of polyphenols with proteins and polysaccharides. J. Chem. Sot. (Perkins Transactions) II. 1429-1443. Nastis, A.S. and Malechek, J.C., 1981. Digestion and utilization of nutrients in oak browse by goats. J. Anim. Sci. 53: 285-299. Nishimuta, J.P., Ely, D.G. and Boling, J.A.. 1974. Ruminal bypass dietary soyabean treated with heat, formalin and tannic acid. J. Anim. Sci., 39: 952-957. Owen, E. and Aboud, A.A.O., 1987. Practical problems of feeding crop residues. In: Reed and Capper (Editors). Plant Breeding and Nutritive Values of Crop Residues, pp. 133-156. Plister, J.A. and Malechek, J.C., 1986. The voluntary forage intake and nutrition of goats and sheep in semi-arid tropics of northern Brazil. J. Anim. Sci., 63: 1078-1086. Reed, J.D., Horvath, P.J., Allen, M.S. and Van Soest, P.J., 1985. Gravimetric determination of soluble phenols including tannins from leaves by precipitation with trivalent ytterbium. J. Sci. of Food and Agric., 36: 255-261.

Reed, J.D., 1986. Relationship amoung soluble phenolics, insoluble proanthocyanidins and fibre in East African browses. J. of Range Manage., 39: 5-7. Reed, J.D. and Soller, H., 1987. Phenolics and N-utilization in sheep fed browse. 2nd. International Symposium on the Nutrition of Herbivores, Brisbane; 6th July, pp. 47-48. Self, R.E., Gallioti, J., Richii, U., Muller-Harvey, I., Hattley, R.D., Lea, A.G., Magnolato, D., Gupta, R. and Haslam, E., 1986. Fast atom bombardment mass spectrometty of polyphenols. Biomed. and Environ. Mass Spectrom. 13: 449467. Seth, O.N., Rai, G.S., Yodar, P.C. and Pandery, M.D., 1976. A note on the rate of secretion and chemical composition of parotid saliva in sheep and goats. Indian. J. Nutr., 54: 545-561. Wachira, J.D., Satter. L.D. Brooke, G.P. and Pope, A.L., 1980. Evaluation of formaldehyde treated protein for growing lambs and lactating cows. J. Anim. Sci., 39: 796-807. Waghom, G.C., Ullyat, M.J., John, A. and Fisher, M.J., 1987. The effect of tannins on the site of digestion of amino acids and other nutrients in sheep fed Lotuscorniculata. Br. J. Nutr. 57: 115126.