Effect of replacing noug seed (Guizotia abyssinica) cake with dried brewers’ spent grain on feed intake, growth performance and dry matter digestibility in sheep fed a basal diet of hay and concentrates

Gebremedhn Beyene, Mulugeta Guesh¹, Kidane Hintsa and Awet Estifanos²

Department of Animal, Rangeland and Wildlife Sciences, College of Dryland Agriculture and Natural Resources, Mekelle University; P O Box: 231, Mekelle, Tigray, Ethiopia
gebremedhnb2008@gmail.com
¹ Wu kro Agricultural Polytechnic College, Tigray, Ethiopia
² Tigray Agricultural Research Institute, PO Box 492, Mekelle, Tigray, Ethiopia

Abstract

The study was conducted at Mekelle University to evaluate the effects of substituting noug seed cake (NSC) with dried brewers spent grain (DBSG) on body weight gain and feed conversion by Tigray highland sheep fed 90 days on a basal diet of 60:40 hay: concentrates. The sheep with an initial body weight 14.8 ±1.23 kg were assigned to four treatments in which dried brewers’ spent grains replaced noug seed cake at levels of: 0, 8, 16 and 30% of the dietary protein.

Feed intake, diet digestibility, growth rate and feed conversion of the sheep were not affected when the noug seed cake was completely replaced by iso-proteic quantites of dried brewers’ spent grains.

Keywords: by-product, daily gain, feed efficiency

Introduction

Ethiopia has 30.7 million sheep distributed from arid to highland areas of the country (CSA 2019).The feed resources for sheep production in Ethiopia are mainly natural grazing and crop residues (Shigdaf et al 2012). There is a seasonal variation in quality and quantity of feed resource (Rahmeto et al 2010). Especially, in the highlands of Ethiopia, grazing resources are diminishing due to increases in cropping land (Adane and Girma 2008). Therefore, during rainy season temporary abundance of forage is followed by long dry periods of scarcity.

Small ruminants require relatively low initial investment capital; they have shorter production cycles, faster growth rates and more environmental flexibility, and thus contribute a significant share to the small holder economy (FAO 2002). Among the small ruminants, sheep add to the livelihoods of resource-poor farmers living under extreme conditions in rural areas. They are essential protein sources in the diets of the poor and help to provide extra income and support survival for many farmers in the tropics and sub-tropics (FAO 2002). The benefits obtained from the sheep resource in Ethiopia are limited due to feed scarcity, inadequate utilization of indigenous sheep breeds, slow growth rate and high mortality of animals. Sheep feeds requirement in the tropics is aggravated by high cost of conventional feeds and lack of alternative source of feed particularly during the dry season when forages are scarce. Therefore, sheep take a long time to achieve the desired market weight, which decreases the farm productivity and overall profitability of the sector.

Noug seed cake is used across all the urban and peri-urban production systems in Ethiopia. Noug seed cake is becoming more expensive due to high grain price (shortage of raw materials) and competition due to less diversified animal feed in the country. However, brewer's spent grain (BSG) is an abundant by-product generated from the beer-brewing process, representing 85% of the total by-products obtained (Mussatto et al 2006). BSG is a raw material which can be used as a source of protein, energy and fiber in livestock diets because of its low cost, and availability throughout the year. Currently, a number of brewery industries are emerging and producing huge amounts of BSG in Ethiopia. This material is basically constituted by the barley grain husks and the residue from the wort (yeast) fermentation. However, little work has been done on the substitution value of brewer’s spent grain to noug seed (Guizotia abyssinica) cake in the ration of sheep. Therefore, this study was designed to evaluate the effect of substitution of noug seed cake with brewers’ spent grain on growth of Tigray highland sheep.

Materials and methods

Description of the study area

The experiment was conducted at the small ruminant farm in the Department of Animal, Rangeland and Wildlife Sciences, Mekelle University, located 783 km far from Addis Ababa, which is found in the Northern part of Ethiopia. Its altitude ranges between 2150 and 2250 meter above sea level and is lying between 13⁰ 28’N latitude and 39⁰ 29’E longitudes. The annual rainfall is 680 mm and mean annual temperature is 17 ⁰C (Alemayehu and Yaynshet 2011).

Experimental animals and their management

20 yearling intact male Tigray Highland sheep with initial live weight of 14.8±1.23 kg were purchased from a local market in Astbi-wenberta. During the 14-day quarantine period the sheep were vaccinated against ovine pasteurellosis and treated with albendazole, and Ivermectin through injection, and sprayed with diazonol against external parasites. The sheep were transferred to individual pens and fed experimental diets for fifteen days to get them adapted to the feeds prior to the commencement of the experiment.

Feeds and feeding management

The diet was a 60:40 combination of grass hay and concentrates. Grass hay was purchased from local farmers, chopped into 10-15 cm length, and offered ad libitum allowing 10-20% refusal. The ingredients of the concntrate (maize grain, wheat bran, cotton seed cake and noug seed cake) were purchased from the local market. Fresh wet brewers’ spent grain was obtained from the Raya Beer Factory and sun dried for three days.

Experimental design and treatments

The animals in individual pens were allocated to four treatments in which BSG provided: 0, 6, 13 and 19% of the concentrate part of the diet replacing equivalent amounts of noug seed cake (Table 1).

Feeding system and measurement of digestibility

The concentrate was offered to the sheep in two equal portions at 9:30 and 4:30. Common salt and fresh water were offered ad libitum. Samples of feeds offered and refusals were collected from each sheep daily and pooled per treatment. The sheep were weighed at the beginning of the experiment and every 10 days of the 90 day experiment. During the last 5 days of the experiment, feces were collected from each sheep and stored at -20°C until the end of the collection period when they were bulked, and sub-samples retained for analysis.

Chemical analysis

Representative samples of feed offered, refusals and feces were ground to pass a 1 mm sieve mesh after drying the feces samples at 65^oC for 48 hours. The DM, ash and nitrogen contents of feed offered, refusals and feces were analyzed using the procedure of AOAC (1990). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were analyzed following the procedure of Van Soest and Robertson (1985). The results are in Table 2.

Statistical analysis

Data were analyzed using the General Linear Model in the ANOVA program of the SAS JMP10 software (SAS 2012). The model was: Y_ij = μ + t_i+ b_j+ e_ij

where; Y_ij = response variable; μ = overall mean; t_i= treatment effect; b_j = block effect; e_ij = random error.

Results

Feed intake and DM digestibility (Table 3) and growth and feed conversion (Table 4) of the sheep were not affected by replacing noug cake with dried brewers’ spent grains (Table 4).

Discussion

The comparable feeding value of dried brewers’ grains to noug cake reflects their similarity in the nature of their crude protein components, which are known to have characteristics that favor partial escape of the protein (bypass protein) from the rumen and hence potential better growth and feed conversion in ruminant animals (Preston and Leng 1987; Promkot and Wanapat 2003).

Conclusion

• Dried brewers’ spent grain fed to fattening sheep at levels providing 30% of the dietary protein supported comparable growth rate and feed conversion as comparable quantities of protein from noug seed cake.

Acknowledgements

The authors acknowledge Mekelle University for financial support to conduct this research work. The authors also acknowledge RAYA BEER Share Company for supporting the brewer’s spent grain for this research.

References

Adane Hirpa and Girma Abebe 2008 Economic Significance of Sheep and Goats. pp. 1-4. Ethiopia Sheep and Goat Productivity Improvement Program (ESGPIP).

Alemayehu Tadesse and Yaynshet Tesfay 2011 Comparative Chemical Composition Evaluation of Local Brewery and Liquor By-Products Made from Different Ingredients. Journal of the Drylands, 4(2):307-309.

AOAC 1990 Association of Official Analytical Chemists. Official Methods of Analysis (13 th ed). Washington D.C.

CSA 2019 Federal Democratic Republic of Ethiopia. Agricultural Sample Survey. Report on Livestock and Livestock Characteristics. Private Peasant Holding. Addis Ababa, Ethiopia.v

FAO 2002 FAOSTAT data (http://faostat.fao.org/faostat/collections?subset=agriculture, accessed on 25-April-2010). Feed Science and Technology, 114:31-41.

Mussatto S, Dragone G and Roberto I 2006 Brewers' spent grain: generation, characteristics and potential applications. Journal of Cereal Science, 43:1-14.

Preston T R and Leng R A 1987 Matching Ruminant Production Systems with Available Resources in the Tropics and Sub-Tropics. http://www.cipav.org.co/PandL/Preston_Leng.htm

Promkot C and Wanapat M 2003 Ruminal degradation and intestinal digestion of crude protein of tropical protein resources using nylon bag technique and three-step in vitro procedure in dairy cattle. Livestock Research for Rural Development. Volume 15, Article #81. http://www.lrrd.org/lrrd15/11/prom1511.html

Rahmeto B, Mebratu G, Solomon M, Fufa A, and Alemayehu R 2010 Gastrointestinal nematode infections in small ruminants under the traditional husbandry system during the dry season in southern Ethiopia. Tropical animal health and production, 42(6):1111-1117.

SAS 2012 SAS JMP statistical discovery Version10.0-HTD-lifetime by SaMeep. SAS institute Inc. Cary, NC.

Shigdaf M, Zeleke M, Mengistie T, Asresu Y, Habtemariam A and Aynalem H 2012 Traditional management system and farmers’ perception on local sheep breeds (Washera and Farta) and their crosses in Amhara Region, Ethiopia. Livestock research for rural development, 24.

Van Soest P J and Robertson JB 1991 Methods of analysis of dietary neutral detergent fiber and non-starch polysaccharides in relation to animal nutrition. Journal of Diary Science, 74:3585-3597.