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Utilization of concentrate diets containing acorns (Quercus aegilops and Quercus coccifera) and urea by growing Awassi lambs
Small Ruminant Research 29 Ž1998. 289–293
Utilization of concentrate diets containing acorns žQuercus aegilops and Quercus coccifera/ and urea by growing Awassi lambs R.A.M. Al Jassim ) , K.I. Ereifej, R.A. Shibli, A. Abudabos Faculty of Agriculture, Jordan UniÕersity of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan Accepted 13 October 1997
Abstract Thirty individually penned Awassi lambs Žmean BW 25.3 " 0.45 kg and 4–5 months of age. were used in a growth experiment. This was followed by a digestion and nitrogen balance experiment using 12 lambs Žmean BW 35.5 " 0.43 kg and 6 months of age.. Lambs in both experiments were divided into three equal groups and fed one of the three concentrate mixes, two of which contained ground acorns Ž Quercus aegilops and Quercus coccifera. at 25% and 50% levels of DM Ž% dry weight.. The aim of the work was to evaluate the usefulness of acorns as an alternative energy source for growing lambs. Concentrates were given according to BW Žrestricted to 3.5% of BW.. Daily weight gain ŽDWG. of lambs fed the control diet or 25% acorn diet was similar Ž186 and 189 g. but higher Ž P - 0.01. than lambs on the 50% acorn diet Ž142 g.. Feed conversion ratio Žkg DMrkg LW gain. was lower Ž P - 0.01. for the 50% acorn diet. Digestibility coefficients of dietary constituents ŽDM, OM, ash, NDF, ADF, and N. were reduced Ž P - 0.001 and P - 0.01. as a result of acorn substitution for barley. Nitrogen retention Žgrday. was also lower Ž P - 0.05. for acorn diets, but similar Ž P ) 0.05. across treatments when expressed as percentage Ž%. of apparently digested N. The low cost of acorns compared with barley suggest that substitution of acorns for barley at a maximum level of 25% would be economically advantageous. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Quercus aegilops; Quercus coccifera; Growth rate; Digestibility; Awassi lambs
1. Introduction The cost of sheep feeding in Jordan can account for more than 85% of the total cost of production. Barley and wheat bran are the major components of the concentrate diet locally used. Local production of )
Corresponding author. Department of Animal Science, University of New England, Armidale NSW 2351, Australia. Tel.: q61-2-6773-5124; fax: q61-2-6773-3275; e-mail: [email protected]
grains is less than the national requirement and it fluctuates from year to year depending on rainfall and market. Until recently, the government in Jordan provided a subsidy for these concentrates but only when given to breeding ewes. Now, sheep holders are forced to search for alternative feed sources. For this reason and because of the high cost of locally available animal feed, lambs are sold for slaughter as rapidly as possible. A recent report from FAO Ž1994. showed that lambs are often slaughtered at a greatly reduced live weight ranging between 18–22 kg in
00921-4488r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 9 2 1 - 4 4 8 8 Ž 9 7 . 0 0 1 2 4 - 7
290
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293
good rainy years and 16–20 kg in bad drought years. The most important challenge is to reduce feeding cost and encourage sheep holders to practise feedlot fattening in order to exploit the high growth potential of lambs over a limited production period. Significant potential exists for the use of locally available non-conventional feed resources such as olive cake, poultry litter, tomato pomace and acorns. Two species of oak trees Žviz. vallenea oak Ž Quercus aegilops . that produce large sweet fruits and kermes oak Ž Quercus coccifera. that produce small bitter fruits. are the most abundant in Jordanian forests ŽMinistry of Agriculture, 1995.. The tentative number of oak trees in Jordan might exceed the number of olive trees that probably number over 6 millions. The estimated annual oak fruit production is about 60,000 tonnes, based on an estimated annual productivity of an average 10 kgrtree Žpersonal communication, Directorate of the Department of Afforestation and Forestry, Ministry of Agriculture, Amman, Jordan.. The objective of this study was to assess the nutritional value of acorns as a substitute energy source in place of barley.
2.2. Diets Acorns from both species Žlarge sweet and small bitter. were collected from four areas in northern Jordan ŽAjloun, Kufrassed, Salhoob and Zay.. The whole fruits Žshells and dicotyledons. were ground fresh, using a local commercial grain mill fitted with 2.5 mm pore size sieve. The ground fruits were then spread under shed to reduce moisture content from initial 47% to less than 20% before being mixed with other dietary ingredients. Partially dried ground acorn mixtures Ž20% large sweet and 80% small bitter. were mixed with other concentrate ingredients ŽTable 1. to provide diets with three levels of acorns Ž0, control; 25 and 50% DM.. Chemical composition of acorns Žshells and dicotyledons. as compared with barley is shown in Table 2. Ingredients and chemical composition of the experimental diets are shown in Table 1. Diets were iso-nitrogenous with similar composition of other Table 1 Ingredients and chemical composition of experimental diets Level of acorns a , Ž% DM. 0
2. Materials and methods 2.1. Lambs and their management Thirty Awassi weaned male lambs Žmean BW 25.3 " 2.44 kg and 4–5 months of age. were randomly selected from the Agricultural Research Centre farm of the Jordan University of Science and Technology, northern Jordan Ž32836X N, 35857X E.. They were divided into three approximately equal blocks based on body weight following the statistical procedure of Sturges Ž1926., and housed in a shed in individual pens with access to fresh water. The experiment included a 14 day Žadaptation. period to enable the lambs to adapt to feed and surroundings and 49 day growth measurement period. Feed offered and refused was weighed daily and BW was recorded weekly Žto the nearest 0.25 kg. prior to feeding. Feed offered was restricted to 3.5% BW. Weight gain was determined by the difference between initial and final BW. Feed conversion ratio was calculated as kg DM intake per kg live weight gain.
25
50
Ingredients (% DM) Barley Corn Wheat bran Soybean meal Acorns Urea Ž46% N. Salt Dicalcium phosphate Minerals and vitaminsb
50 10 25 13 y y 0.5 1.4 0.1
25 10 24.3 13 25 0.7 0.5 1.4 0.1
y 10 23.6 13 50 1.4 0.5 1.4 0.1
Feed costrtonne, ŽUS$.
208.40
183.90
159.40
Chemical composition (% DM) DM 89.0 OM 95.2 CP 18.2 NDF 29.6 ADF 11.7 EE 3.14 GE ŽMJrkg DM. 18.5
85.0 94.6 18.4 35.8 16.3 3.53 18.8
83.0 94.9 18.8 43.2 21.9 3.13 18.6
a
Acorns: whole fruits Žshells and dicotyledons.. Minerals and vitamins mixture Žcomposition per 1000 g.: vitamin A, 450,000 IU; vitamin D3, 1,100,000 IU; vitamin E, 3.18 g; Mn, 10.9 g; I, 1.09 g; Zn, 22.73 g; Fe, 22.73 g; Cu, 2.73 g; Co, 0.635 g; Mg, 100 g; Se, 0.1 g plus antioxidant.
b
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293 Table 2 Chemical composition of fresh acorns Ž Q. aegilops and Q. coccifera. as compared with barley Ž% DM unless otherwise stated. Acorns Žshells and dicotyledons. Q. aegilops Oven DM OM Ash CP CF NDF ADF EE GE ŽMJrkg DM. a
a
53.0 97.6 2.4 3.9 23.6 51.6 35.1 2.5 17.91
Barley
Q. coccifera 53.7 97.2 2.8 2.9 25.3 49.8 26.4 2.3 17.72
86.0 97.4 2.6 10.8 5.3 20.6 6.8 1.7 18.4
Values are the means of six analyses.
nutrients except for NDF and ADF. Urea was used as a source of N to cover the deficit in N content of the acorn diets caused by the substitution of acorns for barley. 2.3. Digestibility and nitrogen balance experiment Twelve Awassi lambs Žmean BW, 37.8 " 3.4 kg and 6 months old. were divided into three equal groups and allocated to the same three experimental diets as were used in the growth study. Lambs were housed in individual pens and allowed 14 day to adapt to the experimental diets, before being transferred into metabolism cages. They had free access to fresh water. Lambs were allowed 7 days to adapt to the cages followed by a 7-day collection period, during which separate collections of total faeces and urine were made. 2.4. Chemical analyses Dry matter concentration of feeds, refusals and faeces was determined by drying samples to constant weight at 1008C in a forced air oven and OM calculated as weight lost during ashing at 5508C for 6 h. Nitrogen concentration was determined by the Kjeldahl method and oil was extracted with petroleum spirit in a Soxhlet extractor ŽAOAC, 1984.. Neutraldetergent fibre and ADF were determined by the methods of Goering and Van Soest Ž1970.. Gross energy content of feeds and faeces was measured using a bomb calorimeter ŽParr Instrument, Moline, IL, USA..
291
2.5. Statistical analyses Data were analyzed by analysis of variance of the randomized block design ŽSteel and Torrie, 1980.. If the F-test for differences amongst groups was significant, the least significant differences ŽLSD. was used to show these differences.
3. Results and discussion Acorns Žshells and dicotyledons. from the different areas and two species contained very little ash, CP and EE with values ranging between 24–28; 29–39 and 23–25 grkg DM for the three components, respectively. All lambs completed the experiment with no signs of health problem. Initial and final BW values, live weight gain, LWG, costrkg gain, costrtotal gain and feed conversion ratios, FCR are presented in Table 3. Lambs fed the 25% acorn diet grew at a similar rate to those fed the control diet. Complete substitution of acorns plus urea for barley Ž50% acorn diet. resulted in a reduction Ž P - 0.01. in LWG. FCR Žkg DMrkg gain. was reduced Ž P 0.01. at the 50% acorns level with no difference between the control and the 25% acorn diets. Digestibility coefficients of all organic constituents were lower Ž P - 0.001. for the acorn diets ŽTable 4.. Increasing the level of acorns in the diet from 25 to 50% resulted in a reduction Ž P - 0.001. in apparent digestibility of organic constituents. The apparent digestibility of the fibre fractions ŽNDF and ADF. were markedly reduced as compared with other organic fractions. The results indicate that acorns may possess some anti-nutritional factors that are responsible for such reduction in digestion of nutrients. Among the several anti-nutritional factors that may exist are polyphenols, a group of tannins that are found to be cellulolytic inhibitors which has been reported in many wild plant, tropical trees, shrubs and forage legumes browsed by ruminants ŽVan Soest, 1982; Jackson et al., 1996.. Flavonoid substances may also be present, although they are relatively harmless in nutrition but contribute to the bitter taste of acorns. Griffiths and Jones Ž1977. reported that tannins have the effect of reducing in vitro digestibility by reduc-
292
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293
Table 3 Effect of dietary substitution of acorns for barley upon live weight ŽLW. gain and food conversion ratio Diets
Number of lambs Initial LW Žkg. Final LW Žkg. LW gain Žgrday. Day 0 to 21 Day 22 to 49 Overall period Food conversion ratio Žkg DMrkg LW gain. Costrkg gain, ŽUS$. Costrtotal gain, ŽUS$.
P
Control
25% Acorns
50% Acorns
10 25.8 " 0.5 34.9 " 0.96
10 24.8 " 0.60 34.1 " 0.96
10 25.2 " 0.40 32.3 " 0.96
182 " 14 190 a " 12 186 a " 11
188 " 14 190 a " 12 189 a " 11
152 " 14 137 b " 12 144 b " 11
NS
4.68 a " 0.66 0.98 8.88
4.79 a " 0.57 0.88 8.19
6.01b " 1.20 0.96 6.80
))
NS
)) ))
)) a,b
P - 0.01; NS, non-significant. Means within same row followed by different superscripts are different Ž P - 0.01..
ing cellulase activity which might be the reason for the drastic reduction in fibre digestibility in our study. Although some tannins are known to have an adverse effect on protein digestion due to their ability to combine with proteins and form leather-like precipitates ŽVan Soest, 1982., moderate levels may
help in protecting soluble proteins from bacterial attack in the rumen ŽBarry et al., 1986; Wang et al., 1996; Perez-Maldonado and Norton, 1996.. Barry and Blaney Ž1987. reported that condensed tannins at low levels can decrease ruminal-N loss and increase intestinal amino acid absorption. In vitro studies of
Table 4 Digestibility coefficients Žmean values " s.e.. of DM, OM, NDF, ADF, CP and GE, energy values and N metabolism as affected by levels of acorns in the diets Level of acorns1 Ž% DM.
P
0
25
50
Digestibility coefficients DM OM NDF ADF CP GE DE ŽMJrkg DM. ME 2 ŽMJrkg DM.
78.7 a " 0.4 81.0 a " 0.6 63.1a " 0.4 46.8 a " 0.5 74.0 a " 0.6 80.1a " 0.6 14.9 a " 0.2 12.0 a " 0.2
71.7 b " 0.4 73.7 b " 0.4 45.9 b " 0.5 28.7 b " 0.7 69.0 b " 0.0 75.0 b " 0.6 14.1b " 0.3 11.4 b " 0.2
66.0 c " 0.4 68.3 c " 0.4 38.3 c " 0.3 9.8 c " 0.7 63.3 c " 0.6 68.8 c " 0.3 12.8 c " 0.1 10.4 c " 0.1
N metabolism Intake Žgrday. Urine Žgrday. Faeces Žgrday. Retained Žgrday. Ž% of digested.
25.92 " 0.0 12.14 a " 0.3 6.72 a " 0.2 7.06 a " 0.2 36.13 " 1.2
25.60 " 0.0 11.49 a " 0.3 7.89 b " 0.2 6.22 b " 0.2 35.20 " 1.2
26.72 " 0.0 10.34 b " 0.2 9.81c " 0.3 6.57 b " 0.2 38.85 " 1.2
1
))) ))) ))) ))) ))) ))) ))) )))
)) ))) )
NS
Acorns: Whole fruits Žshells and dicotyledons.. ) P - 0.05; ) ) P - 0.01; ) ) ) P - 0.001; NS, non-significant. In vivo estimate from ME s 0.81 DE ŽMAFF, 1977.. a,b,c Means within the same row followed by different superscript are different Ž ) P - 0.05; ) ) P - 0.01; ) ) ) P - 0.001.. 2
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293
Waghorn and Shelton Ž1997. showed that proteolysis was reduced to a greater extent than gas production by the presence of condensed tannins. However, condensed tannins at high levels Ž) 5% of dietary DM. can impair ruminant performance by reducing voluntary intake and DM and N digestibility ŽBarry and Duncan, 1984; Galyean and Goetsch, 1993.. The present experiment showed an increase Ž P - 0.001. in faecal output of N, reduction Ž P - 0.01. in urine output and retained N. However, when retained N was expressed as percentage of apparently digested N there was a tendency toward higher value for the 50% acorn diet although differences were not significant. Higher retention could occur, for example, from increases in the supply to the small intestine of limiting amino acids in the dietary proteins that were complexed with acorn tannins and thus protected from rumen degradation. In the lights of our results, the inclusion of acorns in the concentrate mixture of sheep can be economically advantageous ŽTable 3.. To justify the use of higher levels of acorns in diets, the lower animal performance must be weighed against the lower cost of the acorn diet.
Acknowledgements The authors would like to acknowledge The Scientific Research Deanship of the Jordan University of Science and Technology for support. They would also like to thank Dr. John Nolan for reading the manuscript.
References AOAC, 1984. Official Methods of Analysis, 14th edn. Association of Official Analytical Chemists, Arlington, VA, pp. 152–157. Barry, T.N., Blaney, B.J., 1987. Secondary compounds of forages. In: Hacker, J.B., Ternouth, J.H. ŽEds.., The Nutrition of Herbivores. Academic Press, New York, pp. 91–119. Barry, T.N., Duncan, S.J., 1984. The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. Br. J. Nutr. 51, 485–491.
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Barry, T.N., Manley, T.R., Duncan, S.J., 1986. The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep: 4. Sites of carbohydrate and protein digestion as influenced by dietary reactive tannins concentration. Br. J. Nutr. 55, 123–137. FAO, 1994. Sheep Production Under Extension Systems in the Near East, Jordan Pastoral System—A Case Study. Harb, M. ŽEd... Food and Agricultural Organization of the United Nation, Rome, p. 7. Galyean, M.L., Goetsch, A.L., 1993. Utilization of forage fibre by ruminants. In: Jung, H.G., Buxton, D.R., Hatfield, R.D., Ralph, J. ŽEds.., Forage Cell Wall Structure and Digestibility. International Symposium on Forage Cell Wall Structure and Digestibility. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, Madison, WI, pp. 33–71. Goering, H.K., Van Soest, P.J., 1970. Forage Fibre Analysis ŽApparatus, Reagents, Procedures and Some Application.. Agriculture Handbook No. 379, ARS, USDA, Washington, DC, USA, pp. 6–9. Griffiths, D.W., Jones, D.I.H., 1977. Cellulase inhibition by tannins in the test of field beans. J. Sci. Food Agric. 28, 983–989. Jackson, F.S., Barry, T.N., Lascano, C., Palmer, B., 1996. The extractable and bound condensed tannins content of leaves from tropical tree, shrub and forage legumes. J. Sci. Food Agric. 71, 103–110. Ministry of Agriculture, 1995. Training in management of forest and rangelands: Part 1. A management plan for Jordan for the period 1996–2005. Field document No. 8., Amman, Jordan, pp. 38. MAFF, 1977. Energy Allowances and Feeding Systems for Ruminants. Tech. Bull. No. 33. Her Majesty’s Stationary Office, London, pp. 1–4. Perez-Maldonado, R.A., Norton, B.W., 1996. The effect of condensed tannins from Desmodium intortum and Calliandra calothyrsus on protein and carbohydrate digestion in sheep and goats. Br. J. Nutr. 76, 515–533. Steel, R.G.D., Torrie, J.H., 1980. Principles and Procedures of Statistics. A Biometrical Approach, 2nd edition. In: Steel, R.G.D., Torrie, J.H. ŽEds... McGraw-Hill, New York, NY, pp. 137–139, 173–175. Sturges, H.A., 1926. The choice of class intervals. J. Am. Stat. Assoc. 21, 65–66. Van Soest, P.J., 1982. Nutritional Ecology of the Ruminant. O and B Books, Corvallis, OR, USA, pp. 132–134. Waghorn, G.C., Shelton, I.D., 1997. Effect of condensed tannins in Lotus corniculatus on the nutritive value of pasture for sheep. J. Agric. Sci. Cambridge 128, 365–372. Wang, W., Douglas, G.B., Waghorn, G.C., Barry, T.N., Foot, A.G., Purchas, R.W., 1996. Effect of condensed tannins upon the performance of lambs grazing Lotus corniculatus and lucerne Ž Medicago satiÕa.. J. Agric. Sci. Cambridge 126, 87–98.
Utilization of concentrate diets containing acorns žQuercus aegilops and Quercus coccifera/ and urea by growing Awassi lambs R.A.M. Al Jassim ) , K.I. Ereifej, R.A. Shibli, A. Abudabos Faculty of Agriculture, Jordan UniÕersity of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan Accepted 13 October 1997
Abstract Thirty individually penned Awassi lambs Žmean BW 25.3 " 0.45 kg and 4–5 months of age. were used in a growth experiment. This was followed by a digestion and nitrogen balance experiment using 12 lambs Žmean BW 35.5 " 0.43 kg and 6 months of age.. Lambs in both experiments were divided into three equal groups and fed one of the three concentrate mixes, two of which contained ground acorns Ž Quercus aegilops and Quercus coccifera. at 25% and 50% levels of DM Ž% dry weight.. The aim of the work was to evaluate the usefulness of acorns as an alternative energy source for growing lambs. Concentrates were given according to BW Žrestricted to 3.5% of BW.. Daily weight gain ŽDWG. of lambs fed the control diet or 25% acorn diet was similar Ž186 and 189 g. but higher Ž P - 0.01. than lambs on the 50% acorn diet Ž142 g.. Feed conversion ratio Žkg DMrkg LW gain. was lower Ž P - 0.01. for the 50% acorn diet. Digestibility coefficients of dietary constituents ŽDM, OM, ash, NDF, ADF, and N. were reduced Ž P - 0.001 and P - 0.01. as a result of acorn substitution for barley. Nitrogen retention Žgrday. was also lower Ž P - 0.05. for acorn diets, but similar Ž P ) 0.05. across treatments when expressed as percentage Ž%. of apparently digested N. The low cost of acorns compared with barley suggest that substitution of acorns for barley at a maximum level of 25% would be economically advantageous. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Quercus aegilops; Quercus coccifera; Growth rate; Digestibility; Awassi lambs
1. Introduction The cost of sheep feeding in Jordan can account for more than 85% of the total cost of production. Barley and wheat bran are the major components of the concentrate diet locally used. Local production of )
Corresponding author. Department of Animal Science, University of New England, Armidale NSW 2351, Australia. Tel.: q61-2-6773-5124; fax: q61-2-6773-3275; e-mail: [email protected]
grains is less than the national requirement and it fluctuates from year to year depending on rainfall and market. Until recently, the government in Jordan provided a subsidy for these concentrates but only when given to breeding ewes. Now, sheep holders are forced to search for alternative feed sources. For this reason and because of the high cost of locally available animal feed, lambs are sold for slaughter as rapidly as possible. A recent report from FAO Ž1994. showed that lambs are often slaughtered at a greatly reduced live weight ranging between 18–22 kg in
00921-4488r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 9 2 1 - 4 4 8 8 Ž 9 7 . 0 0 1 2 4 - 7
290
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293
good rainy years and 16–20 kg in bad drought years. The most important challenge is to reduce feeding cost and encourage sheep holders to practise feedlot fattening in order to exploit the high growth potential of lambs over a limited production period. Significant potential exists for the use of locally available non-conventional feed resources such as olive cake, poultry litter, tomato pomace and acorns. Two species of oak trees Žviz. vallenea oak Ž Quercus aegilops . that produce large sweet fruits and kermes oak Ž Quercus coccifera. that produce small bitter fruits. are the most abundant in Jordanian forests ŽMinistry of Agriculture, 1995.. The tentative number of oak trees in Jordan might exceed the number of olive trees that probably number over 6 millions. The estimated annual oak fruit production is about 60,000 tonnes, based on an estimated annual productivity of an average 10 kgrtree Žpersonal communication, Directorate of the Department of Afforestation and Forestry, Ministry of Agriculture, Amman, Jordan.. The objective of this study was to assess the nutritional value of acorns as a substitute energy source in place of barley.
2.2. Diets Acorns from both species Žlarge sweet and small bitter. were collected from four areas in northern Jordan ŽAjloun, Kufrassed, Salhoob and Zay.. The whole fruits Žshells and dicotyledons. were ground fresh, using a local commercial grain mill fitted with 2.5 mm pore size sieve. The ground fruits were then spread under shed to reduce moisture content from initial 47% to less than 20% before being mixed with other dietary ingredients. Partially dried ground acorn mixtures Ž20% large sweet and 80% small bitter. were mixed with other concentrate ingredients ŽTable 1. to provide diets with three levels of acorns Ž0, control; 25 and 50% DM.. Chemical composition of acorns Žshells and dicotyledons. as compared with barley is shown in Table 2. Ingredients and chemical composition of the experimental diets are shown in Table 1. Diets were iso-nitrogenous with similar composition of other Table 1 Ingredients and chemical composition of experimental diets Level of acorns a , Ž% DM. 0
2. Materials and methods 2.1. Lambs and their management Thirty Awassi weaned male lambs Žmean BW 25.3 " 2.44 kg and 4–5 months of age. were randomly selected from the Agricultural Research Centre farm of the Jordan University of Science and Technology, northern Jordan Ž32836X N, 35857X E.. They were divided into three approximately equal blocks based on body weight following the statistical procedure of Sturges Ž1926., and housed in a shed in individual pens with access to fresh water. The experiment included a 14 day Žadaptation. period to enable the lambs to adapt to feed and surroundings and 49 day growth measurement period. Feed offered and refused was weighed daily and BW was recorded weekly Žto the nearest 0.25 kg. prior to feeding. Feed offered was restricted to 3.5% BW. Weight gain was determined by the difference between initial and final BW. Feed conversion ratio was calculated as kg DM intake per kg live weight gain.
25
50
Ingredients (% DM) Barley Corn Wheat bran Soybean meal Acorns Urea Ž46% N. Salt Dicalcium phosphate Minerals and vitaminsb
50 10 25 13 y y 0.5 1.4 0.1
25 10 24.3 13 25 0.7 0.5 1.4 0.1
y 10 23.6 13 50 1.4 0.5 1.4 0.1
Feed costrtonne, ŽUS$.
208.40
183.90
159.40
Chemical composition (% DM) DM 89.0 OM 95.2 CP 18.2 NDF 29.6 ADF 11.7 EE 3.14 GE ŽMJrkg DM. 18.5
85.0 94.6 18.4 35.8 16.3 3.53 18.8
83.0 94.9 18.8 43.2 21.9 3.13 18.6
a
Acorns: whole fruits Žshells and dicotyledons.. Minerals and vitamins mixture Žcomposition per 1000 g.: vitamin A, 450,000 IU; vitamin D3, 1,100,000 IU; vitamin E, 3.18 g; Mn, 10.9 g; I, 1.09 g; Zn, 22.73 g; Fe, 22.73 g; Cu, 2.73 g; Co, 0.635 g; Mg, 100 g; Se, 0.1 g plus antioxidant.
b
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293 Table 2 Chemical composition of fresh acorns Ž Q. aegilops and Q. coccifera. as compared with barley Ž% DM unless otherwise stated. Acorns Žshells and dicotyledons. Q. aegilops Oven DM OM Ash CP CF NDF ADF EE GE ŽMJrkg DM. a
a
53.0 97.6 2.4 3.9 23.6 51.6 35.1 2.5 17.91
Barley
Q. coccifera 53.7 97.2 2.8 2.9 25.3 49.8 26.4 2.3 17.72
86.0 97.4 2.6 10.8 5.3 20.6 6.8 1.7 18.4
Values are the means of six analyses.
nutrients except for NDF and ADF. Urea was used as a source of N to cover the deficit in N content of the acorn diets caused by the substitution of acorns for barley. 2.3. Digestibility and nitrogen balance experiment Twelve Awassi lambs Žmean BW, 37.8 " 3.4 kg and 6 months old. were divided into three equal groups and allocated to the same three experimental diets as were used in the growth study. Lambs were housed in individual pens and allowed 14 day to adapt to the experimental diets, before being transferred into metabolism cages. They had free access to fresh water. Lambs were allowed 7 days to adapt to the cages followed by a 7-day collection period, during which separate collections of total faeces and urine were made. 2.4. Chemical analyses Dry matter concentration of feeds, refusals and faeces was determined by drying samples to constant weight at 1008C in a forced air oven and OM calculated as weight lost during ashing at 5508C for 6 h. Nitrogen concentration was determined by the Kjeldahl method and oil was extracted with petroleum spirit in a Soxhlet extractor ŽAOAC, 1984.. Neutraldetergent fibre and ADF were determined by the methods of Goering and Van Soest Ž1970.. Gross energy content of feeds and faeces was measured using a bomb calorimeter ŽParr Instrument, Moline, IL, USA..
291
2.5. Statistical analyses Data were analyzed by analysis of variance of the randomized block design ŽSteel and Torrie, 1980.. If the F-test for differences amongst groups was significant, the least significant differences ŽLSD. was used to show these differences.
3. Results and discussion Acorns Žshells and dicotyledons. from the different areas and two species contained very little ash, CP and EE with values ranging between 24–28; 29–39 and 23–25 grkg DM for the three components, respectively. All lambs completed the experiment with no signs of health problem. Initial and final BW values, live weight gain, LWG, costrkg gain, costrtotal gain and feed conversion ratios, FCR are presented in Table 3. Lambs fed the 25% acorn diet grew at a similar rate to those fed the control diet. Complete substitution of acorns plus urea for barley Ž50% acorn diet. resulted in a reduction Ž P - 0.01. in LWG. FCR Žkg DMrkg gain. was reduced Ž P 0.01. at the 50% acorns level with no difference between the control and the 25% acorn diets. Digestibility coefficients of all organic constituents were lower Ž P - 0.001. for the acorn diets ŽTable 4.. Increasing the level of acorns in the diet from 25 to 50% resulted in a reduction Ž P - 0.001. in apparent digestibility of organic constituents. The apparent digestibility of the fibre fractions ŽNDF and ADF. were markedly reduced as compared with other organic fractions. The results indicate that acorns may possess some anti-nutritional factors that are responsible for such reduction in digestion of nutrients. Among the several anti-nutritional factors that may exist are polyphenols, a group of tannins that are found to be cellulolytic inhibitors which has been reported in many wild plant, tropical trees, shrubs and forage legumes browsed by ruminants ŽVan Soest, 1982; Jackson et al., 1996.. Flavonoid substances may also be present, although they are relatively harmless in nutrition but contribute to the bitter taste of acorns. Griffiths and Jones Ž1977. reported that tannins have the effect of reducing in vitro digestibility by reduc-
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Table 3 Effect of dietary substitution of acorns for barley upon live weight ŽLW. gain and food conversion ratio Diets
Number of lambs Initial LW Žkg. Final LW Žkg. LW gain Žgrday. Day 0 to 21 Day 22 to 49 Overall period Food conversion ratio Žkg DMrkg LW gain. Costrkg gain, ŽUS$. Costrtotal gain, ŽUS$.
P
Control
25% Acorns
50% Acorns
10 25.8 " 0.5 34.9 " 0.96
10 24.8 " 0.60 34.1 " 0.96
10 25.2 " 0.40 32.3 " 0.96
182 " 14 190 a " 12 186 a " 11
188 " 14 190 a " 12 189 a " 11
152 " 14 137 b " 12 144 b " 11
NS
4.68 a " 0.66 0.98 8.88
4.79 a " 0.57 0.88 8.19
6.01b " 1.20 0.96 6.80
))
NS
)) ))
)) a,b
P - 0.01; NS, non-significant. Means within same row followed by different superscripts are different Ž P - 0.01..
ing cellulase activity which might be the reason for the drastic reduction in fibre digestibility in our study. Although some tannins are known to have an adverse effect on protein digestion due to their ability to combine with proteins and form leather-like precipitates ŽVan Soest, 1982., moderate levels may
help in protecting soluble proteins from bacterial attack in the rumen ŽBarry et al., 1986; Wang et al., 1996; Perez-Maldonado and Norton, 1996.. Barry and Blaney Ž1987. reported that condensed tannins at low levels can decrease ruminal-N loss and increase intestinal amino acid absorption. In vitro studies of
Table 4 Digestibility coefficients Žmean values " s.e.. of DM, OM, NDF, ADF, CP and GE, energy values and N metabolism as affected by levels of acorns in the diets Level of acorns1 Ž% DM.
P
0
25
50
Digestibility coefficients DM OM NDF ADF CP GE DE ŽMJrkg DM. ME 2 ŽMJrkg DM.
78.7 a " 0.4 81.0 a " 0.6 63.1a " 0.4 46.8 a " 0.5 74.0 a " 0.6 80.1a " 0.6 14.9 a " 0.2 12.0 a " 0.2
71.7 b " 0.4 73.7 b " 0.4 45.9 b " 0.5 28.7 b " 0.7 69.0 b " 0.0 75.0 b " 0.6 14.1b " 0.3 11.4 b " 0.2
66.0 c " 0.4 68.3 c " 0.4 38.3 c " 0.3 9.8 c " 0.7 63.3 c " 0.6 68.8 c " 0.3 12.8 c " 0.1 10.4 c " 0.1
N metabolism Intake Žgrday. Urine Žgrday. Faeces Žgrday. Retained Žgrday. Ž% of digested.
25.92 " 0.0 12.14 a " 0.3 6.72 a " 0.2 7.06 a " 0.2 36.13 " 1.2
25.60 " 0.0 11.49 a " 0.3 7.89 b " 0.2 6.22 b " 0.2 35.20 " 1.2
26.72 " 0.0 10.34 b " 0.2 9.81c " 0.3 6.57 b " 0.2 38.85 " 1.2
1
))) ))) ))) ))) ))) ))) ))) )))
)) ))) )
NS
Acorns: Whole fruits Žshells and dicotyledons.. ) P - 0.05; ) ) P - 0.01; ) ) ) P - 0.001; NS, non-significant. In vivo estimate from ME s 0.81 DE ŽMAFF, 1977.. a,b,c Means within the same row followed by different superscript are different Ž ) P - 0.05; ) ) P - 0.01; ) ) ) P - 0.001.. 2
R.A.M. Al Jassim et al.r Small Ruminant Research 29 (1998) 289–293
Waghorn and Shelton Ž1997. showed that proteolysis was reduced to a greater extent than gas production by the presence of condensed tannins. However, condensed tannins at high levels Ž) 5% of dietary DM. can impair ruminant performance by reducing voluntary intake and DM and N digestibility ŽBarry and Duncan, 1984; Galyean and Goetsch, 1993.. The present experiment showed an increase Ž P - 0.001. in faecal output of N, reduction Ž P - 0.01. in urine output and retained N. However, when retained N was expressed as percentage of apparently digested N there was a tendency toward higher value for the 50% acorn diet although differences were not significant. Higher retention could occur, for example, from increases in the supply to the small intestine of limiting amino acids in the dietary proteins that were complexed with acorn tannins and thus protected from rumen degradation. In the lights of our results, the inclusion of acorns in the concentrate mixture of sheep can be economically advantageous ŽTable 3.. To justify the use of higher levels of acorns in diets, the lower animal performance must be weighed against the lower cost of the acorn diet.
Acknowledgements The authors would like to acknowledge The Scientific Research Deanship of the Jordan University of Science and Technology for support. They would also like to thank Dr. John Nolan for reading the manuscript.
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