Effect of supplementing urea treated barley straw with doum palm meal (Hyphaene thebaica) on growth of sheep

Twenty-four highland fat-tailed male sheep 6-8 months old; 22.42 kg body weight (BW) were used in the trial and randomly assigned to four treatments of six animals each. Each treatment had 6 lambs with two replicates of 3 in each group. The groups were subjected to 90 days feeding trial to examine the effect of feeding varying amounts of doum palm meal (DPM) on feed intake, water intake and BW of sheep fed a basal diet of urea treated barley straw. Feed and water intake were recorded daily whereas BW was recorded weekly. The sheep were fed an ad libitum basal diet of urea treated barley straw with graded levels of DPM0, DPM100, DPM200 and DPM300 g/head per day of doum palm meal.

Doum palm meal was high in nitrogen free extract (57.3%). The crude protein (CP) content of barley straw was improved from 4.2% to 11.9% following urea treatment. Average dry matter intakes of straw during the experimental period were 908, 923, 993 and 1016 g/animal for DPM0, DPM100, DPM200 and DPM300 respectively. Sheep in all the four treatments ADGed weight. The average daily gain (ADG) obtained for sheep fed urea treated barley straw supplemented with 100g, 200g and 300g doum palm meal (DPM100, DPM200 and DPM300)was significantly different (p<0.05) from sheep fed urea treated barley straw (control diet). Supplementation of 300g of doum palm meal was significantly higher (p<0.05) from sheep fed urea treated barley straw with 100 g and 200 g of doum palm meal (DPM200 and DPM300). Daily water consumption of the sheep was significantly (p<0.001) increased with increasing the level of doum palm meal in the diet. The feed conversion was 30.99, 23.73, 21.63 and 18.92 kg feed/kg ADG for DPM0, DPM100, DPM200 and DPM300 respectively.

Supplementing doum palm meal in combination with urea treated barley straw increased the BW and total feed intake of sheep. The study indicated that doum palm meal can be an alternative animal feed resource in Eritrea.

Introduction

Livestock play a significant role in the Eritrean economy and are essential for food security of the rural population. They are closely integrated with crop production.

One of the major limiting factors to animal production in Eritrea is shortage of feed. Yet this country has feed resources that are inefficiently used and could make a major impact on ruminant livestock production. There are various types of crops grown in Eritrea like wheat, barley, sorghum, taff and millet producing large quantities of crop residues of low nutritive value and intake. The nutritive value and intake of such low quality crop residues can be improved through chemical treatments such as urea treatment.

The bulk of livestock feed in Eritrea comes from grazing on pastures and stubble, conserved crop residues and agro-industrial by products. Agro-industrial by products (AIBP) that include sesame cake, cottonseed and cottonseed cake and wheat bran are available only in limited amounts (Kayouli 2003).

In Eritrea, AIBP used for intensive livestock production are expensive and scarce commodities. It would be advantageous to look for some alternative feed resources such as doum palm meal. According to FAO (1981) doum palm meal supplemented with other protein sources to animals contributes to increase in production. Doum palm (Hyphaena thebaica), is one of the most important species widely available in lowland areas of Eritrea especially in riverine forests such as Gash, Setit and Barka. The riverine forests contain significant amounts of doum palm trees and this resource is so far relatively unexploited as animal feed. The forest of doum palm is important as a habitat for wildlife and enhancing soil and water conservation. The fruits are used as human food. The tree provides an opportunity for income-generating activities for people living in rural areas, particularly women. The leaves are used for thatching the roofs of houses, making fences, mats, ropes, brooms and baskets. Its timber provides termite resistant strong wood used in railroads and as poles for houses. The leaves of the tree provide feed for livestock during the dry season.

The objective of this trail was to examine the effect of feeding different levels of doum palm meal on feed and water intake of sheep fed urea treated barley straw basal diet.

Materials and methods

The experiment was conducted at the College of Agriculture, University of Asmara. The area lies at an altitude of 2342 meter above sea level and receives an annual rainfall of about 500 mm with an average temperature of 18 ^oC (7-22 ^oC).

Doum palm meal was purchased from a private doum palm fruit processing plant around the riverine forest.

Urea treatment was carried out above ground using plastic sheets to cover the treated straw. Five kilograms of urea dissolved in 50 liters of water was sprayed on a 100 kg of barley straw. The solution was sprinkled uniformly over straw using watering cans. The stack was covered tightly with plastic sheets to exclude the entrance of oxygen and prevent ammonia from evaporating. The treated straw was kept for a month before opening for feeding.

Both doum palm meal and urea treated barley straw were analyzed for DM, Ash, CP, CF, EE, Gross Energy and NFE according to the procedures of AOAC (1984).

Feed and feeding trial

Twenty-four highland fat-tailed sheep, six to eight months of age with an average initial BW of 22.42 kg were used in the experiment. The experimental animals were randomly allocated to four treatments of six animals each. Each treatment had 6 male lambs with two replicates of 3 in each group. Lambs were ear-tagged, and prophylaxis treatment was given against internal and external parasites with Ivermectin before the start of the experiment.

The study was conducted for 105 days of feeding consisting of 15 days adaptation period and 90 days of experimental period. Urea treated barley straw was given ad libitum at the rate of 120% of the intake. The supplement was given in separate feeding troughs in the morning and afternoon.

Treatments

Animals in all treatment groups had access to fresh water ad libitum daily. Each group was also provided with a mineral lick.

Initial BW was taken at the start of the experiment and thereafter measurements were taken every week before feeding and giving water. During the experiment, records on the urea treated barley straw DM intake (g/day), doum palm meal DM intake (g/day), total DM intake (g/day), water intake (Lit/day), BW change (g/day) and feed efficiency (kg of feed/kg of ADG) were taken.

Experimental design and statistical analysis

The trials were designed according to a completely randomized design (CRD). BW ADG, water intake and dry matter intakes (DMI) of the animals were analysed using one-way analysis of variance (ANOVA). BW for each group was considered as an experimental unit. Mean BW ADG, water intake and daily DMI were analysed with GENSTAT statistical software. Least significant differences of means (LSD) were used to determine differences between treatments.

Results and discussion

Chemical composition of experimental feeds

The chemical composition of doum palm meal, untreated and urea treated barley straw is shown in Table 1.

Table 1. Chemical composition of doum palm meal, untreated and urea treated barley straw used in the trial
Composition of DM	Doum palm meal	Untreated straw	Treated straw
DM, %	87	93	70
DM basis
CP, %	3.7	4.2	11.9
Ash, %	8.1	7.1	8.4
CF, %	30.5	42.4	42.7
EE, %	0.73	0.98	0.83
NFE, %	57.3	45.3	36
Energy, MJ/kg*	10.4	8.6	8.4
* Calculated value

In this study doum palm meal was used as a supplementary feed. The calculated value of energy in MJ/kg was 10.4 for doum palm meal. Aminah and Chen (1991) indicated that the energy values for most tropical native or improved grasses were between 7 to 11MJ/kg DM. Le Houerou (1996) reported that metabolizable energy of cacti varied from 8.4 to 9.6 MJ/kg DM. The energy content of doum palm meal was comparable to that of sisal pulp with 11.2 MJ/Kg DM (Gebremariam and Machin 2006). The crude protein (CP) and ether extract(EE) contents of doum palm meal were low. The crude protein content of doum palm meal was found to be below the minimum of 7% CP required for normal microbial activity in the rumen (Preston and Leng 1987). Therefore, animals fed with doum palm meal supplemented diets need an appropriate source of a protein supplement. Doum palm meal had 30.5% and 57.3% CF and NFE content, respectively (Table 1). The NFE of doum palm meal used in this study was comparable to that of spineless cactus with 58.16 % (Nefazoui and Ben Salem 2001) and sisal pulp with 59.6% (Daniel 2006). Energy and protein are the most important nutrients for grazing animal productivity (Crowder and Chleda 1982). In order to develop a feeding system using locally available feed resources, the first criteria would be to find an abundant and cheap source of carbohydrate (Preston and Leng 2009). The result of the study proves that doum palm meal is rich in energy content.

Urea straw treatment

Straw, the main source of roughage for most of the year for the majority of ruminant livestock is poor in energy and protein. Digestibility and crude protein content of straw can be improved by urea treatment.

The proximate chemical composition of untreated and urea treated barley straw is shown in table 1. The urea treatment was successful. There was a strongly pungent ammonia smell on opening of the plastic covering after a month. A dark brown color and no mould growth were observed.

Feed intake

The effect of feeding varying amounts of doum palm meal on feed intake of sheep fed urea treated barley straw is presented in table 2. The amount of doum palm meal offered to sheep in this study was restricted. It was highly palatable with no refuse.

Table 2. Mean values for feed intake of sheep fed urea treated barley straw supplemented with different levels of doum palm meal.
Feed intake (DM), g/head/day	Treatments
Feed intake (DM), g/head/day	DPM0	DPM100	DPM200	DPM300
Urea treated barley straw	908^c	823^bc	793^ab	716^a
Doum palm meal	0	100	200	300
Total DM	908^a	923^a	993^a	1016^a
Means in a row having different superscripts differ significantly (p<0.05)

Total DMI of all treatment groups did not statistically differ (p>0.05) from each other. Daily urea treated barley straw intakes were 908, 823, 793, 716 g/animal for DPM0, DPM100, DPM200 and DPM300 respectively. There was a difference (p<0.05) between the control group (DPM0) and the supplemented groups (DPM200 and DPM300). Significant difference (p<0.05) in straw intake was found between the DPM100 and DPM300. As the level of doum palm meal supplementation increased, the substitution level of urea treated barley straw intake by doum palm meal increased. This can be explained by substitutive effect of feed when replaced with a soluble source of carbohydrate (Ndlovu 1992 and Preston 1985). Such an effect was also reported by Njwe and Olubajo (1989) when they supplemented West African Dwarf goats fed fresh Guatemala grass (Tripsacum laxum) with increasing levels of cassava flour and ground nut cake. This substitution could have a negative effect because it decreases straw intake but it has a positive effect as it improves total DMI and animal performance. As the total DMI of sheep increases, the straw intake decreases. This could possibly be associated with a drop in rumen pH. Mould et al (1983) indicated that when roughages are supplemented with a readily fermentable carbohydrate, the rumen pH should remain between 6.0 and 6.1 for normal cellulolytic fermentation. Chenost and Kayouli (1997) indicated that the substitution effect is high for supplements rich in readily fermentable energy due to a fall in pH of the rumen following the rapid production of volatile fatty acids which doesn’t favor cellulolysis.

Increasing doum palm meal level had a positive effect on the total DMI and BW ADG. In this study approximately 90% of urea-treated barley straw offered was consumed. According to Kayouli (1996), treatment improved intake and about 70% of the treated crop residues were edible compared to 30 to 40% for the untreated ones. Improvement of straw intake after urea treatment may vary widely depending on straw quality and treatment conditions (Dass 2000 cited in Sharma et al 2004). Hadjipanayiotou (1982) found that the voluntary intake, crude fiber (CF) and DM digestibility of urea-treated straw were increased by 47, 40 and 26% respectively over the untreated straw.

Effect of doum palm meal supplementation on BW ADG

Table 3. Mean values for performance of sheep fed a basal diet of urea treated barley straw supplemented with varying amounts of doum palm meal.
Parameters	Treatments
Parameters	DPM0	DPM100	DPM200	DPM300
No. of animals	6	6	6	6
Initial LW, kg	22.4	22.4	22.2	22.4
Final LW, kg	25.0	25.9	26.3	27.2
Experimental period, days	90	90	90	90
ADG, g/day	29.3^a	38.9^b	45.9^c	53.7^d
Feed conversion, kg feed/kg ADG	30.9	23.7	21.6	18.9
Cost of feed, Nfa/kg ADG	102	84.0	81.7	75.7
^a ^{b c d}, Means with different superscripts in the same row differ significantly (p<0.05)

Sheep in all the four treatments ADGed weight. BW ADG of animals is highly correlated with DMI and its energy concentration (Moore et al 1999; Solaiman et al 1980). Supplementation of doum palm meal had a positive effect on daily BW ADG of the sheep. The BW ADG of the supplemented groups differed from each other slightly, but both exceeded that of control (Table 3). There was a significant difference (p<0.05) in BW ADG when urea treated barley straw was supplemented with doum palm meal. The reason for higher BW ADG of sheep of supplemented group could be due supplementation of doum palm meal which provided more energy. The NFE content of doum palm meal was higher than that of urea treated barley straw. Thus, the reason for the substitution observed with different levels of doum palm meal supplementation could be a result of better carbohydrate content in doum palm meal compared with treated barley straw. Chenost and Kayouli (1997) showed that a negative interactive digestive phenomenon between the forage and the energy-rich concentrates and substitution of forage by the supplement as the proportion of feed supplements increases. ADGing of BW with the supplemented groups could be due to availability of carbohydrates in the doum palm meal. Sheep fed highly fermentable feeds which include 3% oat hay, 25% maize flour, 15% molasses, 15% sucrose, 12.5% barley grain, 4.5% urea, and 0.5% minerals/vitamins ADGed BW of 45g daily, (Throckmorton and Leng 1984) lower than ADGs obtained in this study.

The ADG of 300g doum palm meal supplementation (DPM300) was significantly higher (p<0.05) from sheep fed urea treated barley straw with DPM100and DPM300. There was also statistically significant difference (P<0.05) in ADG between (DPM100)and supplementation of 200g doum palm meal (DPM200). Supplementation with 300g of doum palm meal resulted in ADG of 53.7 g/day. This was more effective than the unsupplemented group (control), which had ADG of 29.3 g/day (table 3). The result was similar to that found by Habteab (2006) who reported ADG of 51.9 g/day when cactus was supplemented to a urea treated barley straw based diet. ADG of sheep fed 40% urea treated chopped sorghum straw, plus 60% concentrates was 61.7 g (Nianogo et al 1999). In this experiment sheep fed at half the level of concentrates (30%) had ADG (53.7 g/day) that were close to the ADGs (61.7 g/day) obtained by Nianogo et al (1999). Daniel (2006) found that sheep fed a basal diet of barley straw supplemented with 500 g (more than 50%) sisal pulp had BW ADGs of 53 g/day. Comparable BW ADGs were obtained in the current study with a lower (30%) level of doum palm meal supplementation. Supplementation is necessary to obtain adequate animal performance. In this study, supplementation with 300g of doum palm meal (DPM300) resulted in the highest ADG.

The feed conversion efficiency (FCE) increased with increasing levels of doum palm meal supplementation, the lowest being in DPM0 (control group). FCE was highest in DPM300, when urea treated barley straw was supplemented with 300g doum palm meal. The feed conversion was 30.9, 23.7, 21.6 and 18.9 kg feed/kg ADG for DPM0, DPM100, DPM200 and DPM300 respectively. This could be due to the high content of energy in doum palm meal.

Effect of doum palm meal supplementation on water intake

Water intake of sheep with increasing level of doum palm meal is shown in table 4.

Table 4. Water intake of sheep supplemented with varying amounts of doum palm meal
Water Intake	DPM0	DPM100	DPM200	DPM300
Water , Litre/day	1.37^a	1.51^b	1.53^b	1.6^b
Water intake, Litre/kg DMI	1.51	1.64	1.54	1.57
Means with different superscripts (a,b) in the same row differ significantly (p< 0.001);

The intake of water for each kg DMI of feed increased with the increase in doum palm meal supplementation. Daily water consumption of the sheep was significantly (p<0.001) increased with increasing the inclusion level of doum palm meal in the diet. There was statistically significant difference in water consumption between the unsupplemented group (DPM0) and doum palm meal supplemented group (DPM100, DPM200 and DPM300). The reason could be due to high dry matter content of doum palm meal and increasing DMI of sheep. Statistically there was no significant difference (p> 0.05) between the supplemented groups.

Conclusions

References

Aminah, A and CP Chen 1991 Future Prospect for Fodder and Pasture Production. In: Speedy A W and Sansoucy R (editors), Feeding Dairy Cow in the Tropics. FAO Animal Health and Production Paper 86: Rome, Italy http://www.fao.org/ag/aga/agap/frg/AHPP86/Aminah.pdf

AOAC (Association of Official Analytical Chemists) 1984 Official Methods of Analysis. 4^th Edition. AOAC, Washington D C

Crowder L V and Chleda H R 1982 Tropical Grassland Husbandry. Longmans: New York, U.S.A

Daniel Y 2006 Evaluation of Sun-Dried Sisal Pulp (Agave sisalana) as an alternative Ruminant Feed Resource in Eritrea. Unpublished paper

Food and Agriculture Organization 1981 Tropical Feeds: Feed Information Summaries and Nutritive Values. FAO Animal Production and Health Series No. 12. Rome, Italy http://www.fao.org/ag/aga/agap/frg/afris/default.htm

Habteab S 2006 Evaluation of Spineless Cactus (Opuntia ficus-indicus) as an Alternative Feed Resource for Ruminants in Eritrea. Unpublished paper

Hadjipanayiotou M 1982 The Effect of Ammoniation Using Urea on the Intake and Nutritive Value of Chopped Barley Straw. Department of Animal Production, Agricultural Research Institute, Nicosia, Cyprus. 37 (1), 89–93

Kayouli C 2003 “Manual on: methods of analysis and evaluation of feed resources and forages for animal production in Eritrea. (NARI-GCP/ERI/006/ITA)”

Kayouli C 1996 The role of feeding system based on cereal residues in integrated farming systems in Sub Saharan Africa, Livestock feed resource within integrated farming system; Second International Electronic Conference on Tropical feeds, FAO Feed Resource Group, Rome http://www.fao.org/ag/againfo/resources/documents/frg/conf96pdf/kayouli.pdf

Le Houerou H N 1996 The Role of Cacti (Opuntia spp.) in Erosion Control, Land Reclamation, Rehabilitation and Agricultural Development in the Mediterranean Basin. Journal of Arid Environments 33: 135-159.

Moore J E, M H Brant, W E Kunkle and D I Hopkins 1999 Effects of Supplementation on Voluntary Forage Intake, Diet Digestibility, and Animal Performance. Journal of Animal Science 77: 122-135 http://jas.fass.org/cgi/reprint/77/E-Suppl_2/122

Mould F L, Ørskov E R and Mann S O 1983 Associative effects of mixed feeds. I. effects of type and level of supplementation and the influence of the rumen fluid pH on cellulolysis in vivo and dry matter digestion of various roughages. Animal Feed Science and Technology 10:1

Ndlovu L R 1992 Complementarity of Forages in Ruminant Digestion: Theoretical Considerations. Pp. 1-430. In: Stares J E S, A N Said and J A Kategile (editors) The Complementarity of Feed Resources for Animal Production in Africa. Proceedings of the Joint Feed Resources Networks Workshop Held in Gaborone, Botswana 4-8 March 1991. African Feeds Research Network. ILCA: Addis Ababa, Ethiopia http://www.fao.org/wairdocs/ilri/x5519b/x5519b06.htm

Nefzaoui A and H Ben Salem 2001 “Opuntia Spp: A Strategic Fodder and Efficient Tool to Combat Desertification in The WANA Region” In: Mondragon J C and G S Perez (Editors) Cactus (Opuntia Spp.) as Forage. FAO Plant Production and Protection Paper 169: Rome, Italy http://www.fao.org/DOCREP/005/Y2808E/y2808e0d.htm

Nianogo A J, Louis S L, Solaiman S, Charles L O and Arthur S 1999 Effect of Urea Treatment on Digestibility and Utilization of Sorghum Straw. Biotechnology, Agronomy, Society and Environment 3 (2), 78–85

Njwe R M and F O Olubajo 1989 Evaluation of Cassava Flour and Groundnut Cake as Concentrates Supplements for West African Dwarf Goats. Pp. 306-323. In: Said A N and B H Dzowela (editors) Overcoming Constraints to the Efficient Utilization of Agricultural by-products as Animal Feed. Proc, of The Fourth Annual Workshop Held at the Institute of Animal Research, Mankon Station, Bamenda, Cameroun, 20-27 October 1987. ARNAB (African Research Network for Agricultural by-products). ILCA (International Livestock Center for Africa): Addis Ababa, Ethiopia http://www.fao.org/wairdocs/ilri/x5490e/x5490e0o.htm

Preston T R 1985 Associated Effects and Interactions among Feed Ingredients. In: Sansoucy R, Preston, T R and Leng R A (editors), Proc. of the FAO Expert Consultation on the Substitution of Imported Concentrate Feeds in Animal Production Systems in Developing Countries. FAO Animal Production and Health Paper 63: Rome, Italy http://www.fao.org/ag/aga/agap/FRG/AHPP63/63-142.pdf

Preston T R and Leng R A 2009 Matching Ruminant Production Systems with Available Resources in the Tropics and Sub-Tropics. Penambul Books, Armidale NSW

Sharma K, Narayan D and Naulia U 2004 An on-Farm Appraisal of Feeding Urea-Treated Barley Straw to Buffaloes during Late Pregnancy and Lactation in a Mixed Farming System. Livestock Research for Rural Development 16:11 http://www.lrrd.org/lrrd16/11/shar16091.htm

Solaiman S G, F A Martz, M F Weiss and K L Baiyea 1980 Effect of Protein and Energy Supplementation of Guernsey Cow on the Kinetic of Digestion and Passage Orchard Grass versus Alfalfa. Journal of Animal Sciences 50: 2119-2129. http://jas.fass.org/cgi/reprint/68/7/2119.pdf

Throckmorton J C and Leng R A 1984 Effect of By-Pass Protein and By-Pass Starch on Milk Yield and BW ADG in Grazing Dairy Cows. Animal Production in Australia 15:628-630.