Enhancing growth rate, carcass yield and meat quality of Abergelle and Begait sheep breeds through feed management | |
| Author | Gebretsadik, Zelealem Tesfay |
| Call Number | AIT Diss. no.FB-13-01 |
| Subject(s) | Sheep breeds Ethiopia Sheep Ethiopia |
| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Philosophy in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. FB-13-01 |
| Abstract | The farm animal genetic resource (livestock) in Ethiopia has great importance in the livelihood of the small farm households. However, the farm genetic resources and their production constraints in the country are not efficiently characterized and hence, created difficulty for a better and efficient utilization of these resources. Therefore, knowing the animal genetic resources, their importance and constraints vis-à-vis the production system, agro ecology and genotype is inevitable. One of the farm animal genetic resources with significant importance to small households in Ethiopia is sheep. This study focuses on the identification of sheep breeds, their production systems, their values and ways of improving their products in yield and quality, thereby improve the livelihood of small households and microenterprises involved in sheep fattening and meat production. The study focusses on sheep breeds of Northern Ethiopia, more specifically of Tigrai region. Based on morphological characteristics and discriminant analysis, four breeds of sheep have been identified. These are Begait, Abergelle, Ille and the Common Tigrai Highland sheep. The discriminating phenotypes according to their strength of discrimination are face profile (accounting for 83.48% of the difference), tail type (accounting for 17.95% the difference) and compactness (accounting for 2.93% of the difference). Based on the production system assessment, it was possible to identify the major factors affecting flock structure, production constraints, major use of sheep and sheep market chain. The flock structure seems to be affected by the demand, requirement of breeding female, feed availability and the occurrence of disease and natural calamities. Farmers tend to keep more female sheep for longer (culling age of 5.9 ± 0.4 and 1.9 ± 0.5 for females and males respectively) for the reasons of feed shortage and requirement for breeding female. The ratio of male to overall female is small (1:6) and hence rams has maximum contact time with ewes that might contribute for inbreeding. The overall average age at puberty for female is 9-14 months. However, the presence of very young lamb rams and uncontrolled mating system led to early breeding of females which resulted in low conception rate, low birth weight, poor survival rates and in extreme cases causing inbreeding. The market structure for live animals in Tigrai region has four hierarchies with extremely poor infrastructure further affecting the provision of quality meat to the end consumer. In this survey was also noted that five critical control points such as choice of breed (especially sire), age of animals, feed & feeding, animal diseases & pests and the market infrastructures need to be given emphasis to ensure supply of live animal for better quality meat and profitability of the producers. In the effort to improve growth performance and meat quality of two sheep breeds (Abergell and Begait sheep). Thirty rams aged between six and eight months (fifteen each) from two sheep breeds were kept under three diet treatments containing two different ratios (3:2 and 1:1) of wheat bran and sesame seed cake along with grazing. The animals were not fed with wheat bran and sesame seed cake was kept as control. The total amount of supplement was 600 g per day. The animals were left for grazing at the same time with the same types and amount of materials. The growth performance, carcass characteristics, meat quality and fatty acid contents were assessed after two months of feeding trial. Abergelle breed has higher value for moisture (71.38%) and ash (2.55%) contents and dressing percentage (49.13%) (p < 0.001). Begait breed had higher values (p <0.01) for hot and cold carcass yield (12.43 kg and 12.24 kg respectively). Over 51% dressing percentage was achieved in supplemented groups compared to 45% for non-supplemented groups. Generally it was managed to attain a daily growth rate of 160- 180g and 173-175g for Abergelle and Begait breed respectively on grazing rams supplemented with 600g of SSC and WB mixture. Water holding capacity and pH (after 24 h of stored meat; pH24) were found similar for both breeds [(15.64-15.76) and (5.6) for water holding capacity and pH24 respectively] (p > 0.05). However, cooking loss and tenderness showed significant difference (p < 0.01) between breeds. Begait breed had lower values for cooking loss (24.68 Vs. 26.55). Long chain fatty acids such as Palmitic (C16:0), Stearic (C18:0), Oleic (C18:1n-9) and Linoleic (C18:2n-6) have showed a significant differences among the breeds (p < 0.01). Meat form Begait sheep had higher concentration of C18:0 (18.18 Vs. 16.47) and C18:1n-9 (36.46 Vs. 35.52) while meat form Abergelle sheep had higher values for C16:0 (25.02 Vs. 24.36) and C18:2n-6 (6.58 Vs. 6.30). Supplementation of wheat bran and sesame seed cake brought significant change on concentration of Pentadecylic (C15:0) and Linoleic (C18:2n-6) only, with other fatty acid concentrations showed no change (p >0.05). Based on the meat quality measurements and the fatty acid profile, it was concluded that the meat from the two breeds (Abergelle and Begait) had acceptable levels of fatty acids especially the Oleic and Linoleic; and had optimum levels of cooking loss and WHC. |
| Year | 2013 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. FB-13-01 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Anal, Anil Kumar |
| Examination Committee(s) | Athapol Noomhorm;Rakshit, Sudip Kumar;Yakupitiyage, Amararatne |
| Scholarship Donor(s) | Ministry of Agriculture, Ethiopia |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2013 |