Body weight and carcass characteristics of Washera sheep fed urea treated rice straw supplemented with graded levels of concentrate mix

Abebe Hailu, Solomon Melaku^*, Berhan Tamir^** and Asaminew Tassew^***

Woreta ATVET College, P. O. Box 06, Woreta, Ethiopia
* Haramaya University, P. O. Box 138, Dire Dawa, Ethiopia
** Faculty of Veterinary Medicine, Addis Ababa University, P. O. Box 34, Debre Zeit, Ethiopia
*** College of Agriculture and Environmental Sciences, Bahir Dar University, P. O. Box 276, Bahir Dar, Ethiopia
atassew2005@yahoo.com

Abstract

An experiment was conducted for ninety days of feeding trial to evaluate the response of Washera sheep on body weight gain and carcass parameters when fed urea treated rice straw (UTRS) and supplemented with graded levels of concentrate mix consisting of wheat bran (WB), brewers dried grain (BDG) and noug seed cake (NSC) at a ratio of 35: 30: 35, respectively at Woreta ATVET College, North Gondar, Ethiopia. The treatments were UTRS alone (CM0), UTRS + 200 g concentrate mix (CM200), UTRS + 300 g concentrate mix (CM300) and UTRS + 400 g concentrate mix (CM400) on dry matter base / head /day. At the end of the feeding trial, sheep were slaughtered for carcass parameter determination.

Total DM intake was higher (P<0.001) for the supplemented treatments compared to the control. The DM intake of UTRS excessively decreased (P<0.001) with the increase in the level of supplementation. Final body weight, daily body weight gain and empty body weight were higher (P<0.001) for supplemented sheep than for sheep on the control treatment. The mean slaughter weight was significantly lower (P<0.001) for CM0 than CM400. CM200 was better in terms of live weight gain, and carcass component than the sheep in other treatments.

Conduct on farm trials using similar treatments and rice straw as basal feed supplemented with other source of proteins and energy found in the area and/or improving rice straw with different levels of urea or other non conventional protein source should be evaluated to assure this study for actual uses at farmer levels.

Key words: Body weight gain; carcass parameters; feeding trial; slaughter weight

Introduction

In spite of the high population and wide distribution, the present productivity of sheep in Ethiopia is very low. For instance average carcass output per sheep is estimated to be 10 kg (FAO 2001). The same source also confirmed that meat production per head is lower for sheep in Ethiopia than in neighboring countries such as Sudan, Somalia, Djibouti and Kenya, which respectively produce 13, 13, 12, and 13 kg/head. This low productivity of sheep in Ethiopia could be particularly attributed to poor nutrition, since studies (Seyoum and Zinash 1995; Tsige 1999) reported poor nutrition to be the major constraint for livestock production in Ethiopia.  

Crop residues and other agricultural by-products once categorized as wastes have become major components of livestock feed in many countries in the world. On the other hand, most crop residues are low in metabolizable energy (ME) (<7.5 MJ/kg DM), low in digestibility (<50%), low in crude protein (CP) (<6%) and low in minerals as well as vitamin content (Owen 1985). Similar to other crop residues, the nutritive value of rice straw is low with chemical composition of 31.5% CF, 44% TDN, 1.9 MJ ME /kg DM, 4.3% CP, 0.04% Ca, 0.09% P, and 12-13% silica (Ensminger et al 1990). The digestibility and feed intake of rice straw is low due to its high cell wall (790 g/kg DM), cellulose (330 g/kg DM) and lignin (70 g/kg DM) contents (Ranjhan 2002). Therefore, this study was conducted to assess the effect of urea treatment and supplementation with graded levels of concentrate mix on the improvement in the utilization of rice straw. 

Materials and methods

Study area

The study was conducted at Woreta Agricultural Technical and Vocational Education Training (ATVET) College in the Amhara national regional state, Ethiopia. Wereta is located at about 45 kms south-east of Bahir Dar, the capital of Amhara region. It has an average altitude of 1802 m a.s.l. and receives mean annual rainfall of 1259 mm and has a mean temperature range of 19.9°C to 28.2°C.  

Experimental feeds and treatment of rice straw 

Rice straw and urea used in this experiment was purchased from local farmers and Woreda Bureau of Agriculture, respectively. Before treatment of straw with urea, the straw was chopped to about 5-10 cm size. Four kg of urea dissolved with 80 litter water was used to treat 100 kg of rice straw (Chenost and Kayouli 1997). The treated straw was filled in to pit to which the walls are covered with polyethylene sheet, compacted to make it air tight and sealed with polythyline sheet and loaded by soil on top. The ensiled straw was left unopened for three weeks for proper treatment to occur as recommended by Sundstøl and Owen (1984).

The ensiled stocks were aerated overnight under shade before offer to animal to eliminate volatile ammonia that causes ammonia toxicity if fed to animals without aeration. Supplement feeds, namely, Noug Seed Cake (NSC) and Wheat Bran (WB), were purchased from Woreta town and brewery dry grain (BDG) was purchased from Gondar Dashen Breweries factory. The breweries grain was air dried under shade. Common salt block was purchased from local market in the area.  

Animals and feeding management

Twenty yearling intact male Washera sheep with mean body weight of 17.15±1.35 kg purchased from the local market were used. The experimental animals were housed in individual pens equipped with feeding and watering troughs. They were quarantined for 15 days to observe any disease situation and were vaccinated against ovine pasteurellosis, sheep pox, blackleg, and anthrax, dewormed against internal parasites and sprayed against external parasites. 

Experimental design and treatments

The experiment was conducted using a randomized complete block design (RCBD). The animals were blocked into five blocks of four animals each based on their initial body weight. The treatments consisted of supplementing three different levels of concentrate mix (CM) on dry matter (DM) basis to experimental sheep fed on urea treated rice straw (UTRS). The CM consisted of 35% NSC, 35% WB and 30% BDG. The proportion of the CM was formulated based on TDN for maintenance and growth requirements (NRC 1985) by considering initial average body weight of 16-20 kg of experimental animals with expected 30 g weight gain per day at the low level of supplementation. 

The treatments were:

• CM0: Urea treated rice straw

• CM200: Urea treated rice straw + 200 g DM concentrate

• CM300: Urea treated rice straw + 300 g DM concentrate

• CM400: Urea treated rice straw + 400 g DM concentrate

 The four treatments were randomly assigned to animals in each block, resulting in five animals per treatment.  

Data collection

Daily feed offered and refused was collected and recorded for each animal throughout the experimental period. Body weight was taken at every ten days interval after overnight fasting using suspended weighing scale.At the end of the experiment, all the experimental sheep were fasted for 12 hours, weighed and slaughtered. The animals were slaughtered following the standard slaughtering procedures for sheep. Blood was collected into a bucket and weighed. The external and internal offals such as head + horn, skin + feet, testis + penis, kidney, lungs + trachea, heart, liver, spleen, reticulo-rumen with contents, omaso-abomasum with content, intestine with content were weighed and recorded.

The carcass was chilled overnight in a refrigerator for proper cutting. Both the right and left halves of the carcass were cut between 11^th and 12^th ribs perpendicular to the backbone to measure a cross-sectional area of the rib eye muscle by tracing on graph paper and then determining the area using Planimeter. Empty body weight was calculated as the difference between slaughter and gut contents. Percentage of total edible offal components (TEOC) was calculated as the sum total of blood, lung+ trachea, heart, liver empty gut, and kidney. The percentage of total non-edible offal components (TNEOC) was considered as the sum of head, skin with feet, penis + testicle, omental fat from kidney and abdomen, spleen, gall bladder, and gut content. Both TEOC and TNEOC percents were calculated based on SBW. The dressing percentage was calculated on the hot carcass as proportion of the slaughter weight as well as empty body weight. 

Statistical analysis

All the data on feed intake, body weight change and carcass parameters were analyzed using the General Linear Model (GLM) procedure of the  statistical analysis system (SAS 2002). Treatment means were separated using least significance difference test. The model used for the analysis of growth, feed intake and carcass parameters was:

Y_ij = µ + T_i + B_j + e_ij

Where:    

Y_ij = The observation on body weight, feed intake and carcass characteristics

µ = Overall mean

T_i = The fixed effect of diet

B_j = Block effect

e_ij= effect of random error

Results and discussion

Feed intake

The feed intake of Washera sheep fed UTRS supplemented with graded levels of concentrate mixture is given in Table 1. The result of the experiment showed that there was significant difference (P<0.001) in UTRS dry matter intake (DMI) between treatments. UTRS DMI was higher (P<0.001) for the non-supplemented compared to the supplemented sheep. Among the supplemented sheep, UTRS DMI decreased (P<0.001) with increasing levels of concentrate supplementation. The result was similar to that of Mulu (2005) and Tesfaye and Solomon (2008) in which concentrate mix supplementation reduced intake of teff straw and hay basal diet with increasing supplementation levels. In addition, Solomon and Simret (2008) also reported similar results with the current study. 

The result of this experiment showed a significant difference (P<0.001) in total DM intake (TDMI) between the supplemented and control treatments. Accordingly, TDMI was higher (P<0.05) for the supplemented than non-supplemented treatment groups. The result of this study was in line with the result of other studies (Mulu 2005; Solomon and Simret 2008). The CP intake in relation to DMI was different (P<0.001) among treatment groups; it increased from the control to the higher levels of supplementatin. Similar to the results of the current study, Tesfaye and Solomon (2008) observed that increase in total DM intake with increase of supplementation of graded levels of concentrate mix to teff straw as a basal feed in Afar ram. Similarly, Dawit and Solomon (2008) reported that the decline in DM intake of urea treated barely straw (UTBS) at higher levels of supplementation with forage legumes hay. This could be attributed to the high proportion of the supplement in the total diet. This study also showed that TCP intake increased while CP intake from UTRS decreased as supplementation level increase. 

Body weight change

The mean final body weight and mean daily live body weight gain obtained in the present study was higher (P<0.001) for the supplemented treatments compared to the control treatment (Table 2). The weight loss from sheep fed on the control treatments could be attributed to the lower total DM intake and CP intakes as compared with those on supplemented treatments. The result of weight gain observed from this study is nearly similar with the value reported by Mulu (2005) for Wogera sheep fed grass hay basal diet supplemented with graded levels of BDG and by Solomon and Simret (2008) for Somali goats fed grass hay basal diet supplemented with concentrate mix. Contrary to this, Dawit and Solomon (2008) and Getahun (2001) reported higher weight gain per day than the weight gain observed in the current study in Arsi Bale sheep fed urea treated barley straw (UTBS)  supplemented with vetch and alfalfa and sheep fed urea treated wheat straw (UTWS) basal diet supplemented with different levels of Leucaena lecocephala, respectively. The reason for the supplemented groups have superior body weight gain than non supplemented ones, might be due to an increase in nutrient density as the result of protein supplementations and reflection of an increase in gastrointestinal fill as result of the higher total DM and nutrients intake of the animals.  

As observed in the control group, the daily gain was negative; this could be due to less nutrient density extracted from basal diet that did not fulfill the daily requirement of the animals, so they were forced to lose their body reserve. This idea was supported by McDonald et al (2002) in that feeds which have less than 8-9% CP do not support adequate microbial activity in the rumen, thus consequently limiting digestion rate in the rumen. This holds true in as the control sheep fed only UTRS the CP in DM was only 7.8%, which is marginal to the maintenance requirement of the animal. The results of this study agree with the importance of supplementation of a CP source feed animals fed fibrous diets (Devendra and McLeroy 1982). 

The linear regression  between the dependent variable of daily body weight gain, and the independent variable of CP as % of DM (Figure 1), indicated the importance of the protein supply as the primary determinant of thegrowth of sheep fed basal straw-based diets. Abule et al (1998) reported that goats supplemented with a concentrate mix gained more weight compared with non-supplemented ones. 

Figure 1. Regression of crude protein as percent of DM intake on daily body weight gain of Washera sheep fed UTRS basal diet and supplemented with graded levels of concentrate mix.

Carcass characteristics

The mean slaughter weight of CM400 was higher than the control treatment (Table 3). Empty body weight was not different among treatments. This result is in agreement with reports in other similar studies (Tesfaye and Solomon 2008; Abebe et al 2009). 

 In the present study, fat thickness and rib eye area was not different (P>0.05) among treatments. The rib eye area result of this study was higher than the result reported by Mulu (2005) with value of 5.20-8.80 cm² of rib eye on Wogera sheep, from 5.20-8.80 cm² for Hararghe Highland goats (Asnakew 2005). However, the rib eye area observed in this study was lower than that reported by Gebregzibiher et al (2003) for Horro lambs (29.7 cm²) supplemented with 800 g maize+1040 g Sesbania: concentrate mix.  

Supplemented treatment groups had higher (P<0.05) total edible offal contents. This result is in agreement to that reported by Mulu (2005) in Wogera sheep where the supplemented treatments had higher total edible offal than the non supplemented ones. There was no difference in total offal, total non-edible offal (%) between supplemented and control groups as well as between the supplemented treatments. In contrast to the current result Tesfaye and Solomon (2008) and Asnakew (2005) reported heavier total non-edible offal for Afar rams and Hararghe Highland goats fed on teff straw and hay basal diet and supplemented with concentrate, respectively. Similar other result was also reported by Mulu (2005).

Correlation between live weight change and carcass parameters

The orrelation analysis for live weight change and carcass parameters s presented in Table 4. The correlation analysis showed that daily weight gain (DWG) was significantly and positively (P<0.01) correlated with slaughter body weight (SBW), empty body weight (EBW), rib eye area (REA), back fat thickness (BFT), edible offal component (EOC) and non-edible offal components (NEOC). The SBW had a weak positive correlation (p> 0.05) with dressing percentage (DP) while, others such as EBW, HCS, REA, BFT, EOC and NEOC were significantly and positively (P<0.01) correlated with SBW like that of DWG.  Hot carcass weight (HCS) was highly and positively (P<0.01) correlated with DP and REA, and also significantly and positively (P<0.05) correlated with BFT and EOC. NEOC had weak but positive association with HCS. Dressing percentage (DP) was correlated negatively with NEOC and positively but weak association with EOC. The result of this study is in agreement with the result of Tesfaye and Solomon (2008) that reported positive correlations between rib eye area, slaughter body weight, hot carcass weight, dressing percentage, visceral fat, liver and kidney with daily weight gain in afar rams. Similarly, Asnakew (2005) also observed positive correlations between slaughter body weight, hot carcass, rib eye area (REA) and back fat thickness (BFT) in Hararghe highland goats. 

Conclusions

Supplementations of Washera sheep with concentrate mix had a positive effect on feed intake, weight gain and carcass parameters.  

Acknowledgements

The financial assistance provided by the Amhara Region Bureau of Agriculture and Rural Development is gratefully acknowledged.  

References

Abebe Tafa, Solomon Melaku and Kurt J. Peters 2009 Supplementation with linseed (Linum usitatissimum) cake and/or wheat bran on feed utilization and carcass characteristics of Arsi-Bale sheep. Tropical Animal Health and Production, 10.1007/s11250-009-9475-8

Abule E, Amsalu S and Tesfaye A 1998 Effects of supplementation of lablab (Dolichos lablab) for concentrate mix on growth tare and efficiency in post weaning native goats. Pp.264-268. In: proceeding of six annual conference of Ethiopian Society of Animal Production (ESAP). 14-15 may, 1998, Addis Ababa, Ethiopia.

Asnakew Awuk 2005 Feed lot fattening performance and carcass characteristics of intact male Hararghe highland Goats fed different levels of hay to concentrate ratios. MSc. Thesis Presented to the School of Graduate Studies of Alemaya University of Agriculture, Alemaya, Ethiopia.  81p.

Chenost M and C Kayouli 1997 Roughage utilization in warm climate, FAO (Food and Agriculture Organization of the United Nation), Animal Production and Health Paper 71 Rome. 34-56pp.

Dawit Abate and Solomon Melaku 2008 Effect of supplementing urea-treated barley straw with lucerne or vetch hays on feed intake, digestibility and growth of Arsi Bale Sheep.  Tropical Animal Health and Production, 10.1007/s11250-008-9227-1

Devendra C and B G McLeroy 1982 Goat and Sheep production in the tropics. Longman, London and Newyork. 192p.

Ensminger M E, E J Oldfield and W M Hernemann 1990 Feed and feeding. 2^nd (ed.). Ensminger publishing Campany, United State, California. Pp.925-926.

FAO (Food and Agricultural Organization) 2001 Production year book. Vol.55. FAO, Rome, Italy.

Gebregziabher G, Dirba G, Lemma G, Yohannes G and Gemeda D 2003 Effect of noug cake and sesbania sesban supplement on growth performance and carcass characteristics of Horro lambs. Proceedings of 10^th annual conference of Ethiopian Society of Animal Production (ESAP) held in Addis Ababa, Ethiopia, August 21-23, 2003.

Getahun L 2001 Growth pattern and carcass characteristics of Somali and Mid-rift valley Goats. MSc. Thesis presented to School of Graduate Studies of Alemaya University, 106p.

McDonald P, R A Edward, J F D Greenhalgh and G A Morgan 2002 Animal nutrition 6^th ed. Pearson Educational Limited. Edinburgh, Great Britain. 544p.

Mulu Moges 2005 Effects of feeding different levels of breweries dried grain on live weight gain and carcass characteristics of Wogera Sheep fed on hay basal diet.  MSc. Thesis  Presented to Alemaya University of Agri.  Dire Dawa. Ethiopia. 54p.

NRC (National Research Council) 1985 Nutrient requirements of domestic animals, 15. Nutrient Requirements of sheep: dairy and meat goat in temperate and tropical countries. National Academy Press, Washington D.C. USA. 91p.

Owen  E 1985 Crop residues as animal feeds in developing country –use and potential use. In: Wanapot, M and Devendra, C. (eds.). Relevance of crop residues in animal feeding in developing country. Funny  press, Bangkok. Pp. 25-42.

Ranjhan S K 2002 Animal nutrition in tropics. 5^th  (ed). Vikas publishing House. PVT.  LTD. 543P.

SAS (Statistical Analysis System) 2002 Procedures Guide for Computers. Version 6.12. SAS. institute.

Seyoum B and Zinash S 1995 Chemical composition, in vitro digestibility and energy values of Ethiopian feedstuffs. Pp. 307-311. Proceedings of the 3^rd  National conference of the Ethiopian Society of Animal Production (ESAP), Addis Ababa, Ethiopia,27-29 April 1995, ESAP, Addis Ababa.

Solomon Melaku and Simret Betsha 2008 Bodyweight and carcass characteristics of Somali goats fed hay supplemented with graded levels of peanut cake and wheat bran mixture. Tropical Animal Health and Production, 10.1007/s11250-008-9133-6

Sundstøl F and E Owen 1984 Straw and other fibrous by products as feed, Amesterdam Sci. pub. com, New York. Tokyo. 604 pp.

Tesfay Hagos and Solomon Melaku 2008 Feed intake, digestibility, body weight and carcass parameters of Afar rams fed tef (Eragrostis tef) straw supplemented with graded levels of concentrate mix. Tropical Animal Health and Production, 10.1007/s11250-008-9230-6

TsigeYohannes H 1999 Livestock feed security and associated impacts on sustainable agricultural development. pp. 51-61. Proceedings of the seventh annual conference of Ethiopia Society of Animal Production (ESAP), Addis Ababa, Ethiopia, 26-27 May 1999, Addis Ababa.

Received 28 December 2010; Accepted 14 May 2011; Published 3 August 2011

Go to top