EFFECT OF AGE AND BREEDS OF CATTLE ON CARCASS AND MEAT CHARACTERISTICS, EATING QUALITY, PROXIMATE COMPOSITION AND FATTY ACID PROFILE IN OROMIA NATIONL REGIONAL STATE, ETHIOPIA

Abstract

The objectives of this study were to determine the effect of age and breeds of cattle on carcass and meat characteristics, beef eating quality, fatty acid profile and proximate composition of meat. A total of 39 (Arsi 11, Borana 14 and Harar 14) cattle breeds with age categories of <3, 4-6 and 7-9 years were used. Arsi and Harar bulls were purchased from mixed crop livestock production system and Borana bulls from Didu Tiyura Ranch. Complete randomized design was used for the study. Both age and breeds of cattle had significant effect (P<0.05) on meat and carcass characteristic, eating quality, fatty acid profile and proximate composition. To meet the first objective, live and carcass weight, meat yield percent, fat characteristics, and primal beef cuts were determined.The live weight of bulls at <3, 4-6 and 7-9 years ranged 135-183, 167-181, and 155-433kg, respectively. The carcass weight, dressing percentage, forequarter, hindquarter, rib eye area, and fat thickness ranged 57-209.73kg, 41.8-51.6%, 11.7-56.42kg, 14.04-45.34kg, 4.78-10.25 square inches and 0.18-0.38 inches, respectively. At an early age category (<3 years) meat yield percentage of Arsi, Borana and Harar breeds were 50.86, 30 and 18.72, respectively, and as age shifted from one category to the next Harar increased by 13x and Borana by 2.9x and Arsi decreased by -0.93x indicating that as age advanced saleble meat yeild increase in Borana and Harar whereas decreased in Arsi. The mean rib percentage of Arsi, Borana and Harar were in the range of 7.98 – 9.57, 8.62 – 10.44 and 7.08 – 8.83, respectively. Meat yield was predicted from hot carcass weight with coefficient determination (R2) of 88.65% and 99.60% for Arsi and Borana, respectively and chuck with R2 of 94.6% for Harar breeds. . To meet the second objective instrumental and sensory tenderness, juiciness, flavor, color and water holding capacity were evaluated. At 7-9 years mean flavor of Borana was significantly better than (P<0.05) Arsi breed. At age <3 years mean sensory juiciness of Borana cattle was higher (P<0.05) than Arsi. At age < 3 years mean sensory tenderness of Borana was significantly (P<0.05) lower than Arsi. In all xvii age categories Arsi recorded higher (P<0.05) instrumental tenderness than Borana and Harar. The mean instrumental tenderness using Warner-Bratzler Shear Force (WBSF) values of Arsi, Borana and Harar at age category <3 years, between 4 and 6 and between 7 and 9 were 30.27, 15.83 and 15.12, 42.89, 20.49 and 16.97, and 55.52, 24.73 and 24.80, respectively. Mean flavor value of Arsi breed was lower (P<0.05) than Borana and Harar breeds. Mean Juiciness value of Borana breed was higher (P<0.05) than Arsi and Harar breeds. Except for beef from Arsi bulls between 4 and 9 years, the tender value in all age categories of the three breeds were in the range of very tender classification. Borana (<3 years) beef was higher (P<0.05) in lightness (L*) than Arsi and Harar indicating better quality beef. All breeds were similar in meat redness (a*), yellowness (b*) and water holding capacity across age categories. Beef flavor negatively correlated with juiciness, tenderness and L*. Beef lightness (L*) negatively correlated with a*, WHC and instrumental tenderness and positively correlated with b*. In the third study fatty acid profile and proximate composition were investigated. Up to 6 years (<3 to 6 years) of age Arsi deposited higher (P<0.05) Myristic acid than Borana and Harar. At younger age (<3 years) category Arsi deposited higher (P<0.05) Linolenic acid than Borana and Harar. At younger age (<3 years) categories Borana and Harar were better in Arachidonic acid concentration than Arsi. In all ages (<3 to 9 years) categories Harar contains higher concentration of Linoleic acid than Arsi and Borana. The concentration of Polyunsaturated Fatty Acid (PUFA) was higher than SFA in all breeds across age categories. The three breds were similar in Monounsaturated Fatty Acid (MUFA), n-3, n-6 and n-6: n-3 concentarations. Crud fat composition was significantly different among Arsi, Borana and Harar bulls at age categories under 3 years and 7-9 years. At younger age (<3 years), Harar bulls deposited higher (P<0.05) fat percentage in its carcass than Arsi bulls while not different from Borana bulls. Meat from Arsi bulls at age 7-9 years contained lower (P<0.05) mean fat percentage than meat from Borana and Harar bulls. At younger age (< 3 years) Arsi bulls produced higher (P<0.05) percent protein content than Borana and Harar bulls. Between 7 to 9 years Borana and Harar bulls meat contain higher (P<0.05) crud protein percent than Arsi. Based on the present work, it was concluded that the dressing percentage and meat yield percentage of the three breeds were relatively low. Borana bulls were potential for meat yield and carcass characteristics. xviii The increase in meat yield percentage for Harar bulls up to 9 years indicative of the presence of good management practice of Harar farmers for their bulls. Arsi bulls older than four years of age produced tougher beef suggesting the use of this breed for beef at early age. Borana and Harar produce very tender meat, and better for juiciness and flavor production. Arsi bulls up to 6 years and Borana at old age (7-9 years) had more Myristic acid compared to Harar bulls. All breeds produces essential fatty acid (linolenic and linoleic acids) which are good for human health. Nutritionally, meat from Harar and Borana bulls deposited relatively more fat and where as Arsi at early age accumulated more protein. Generally, the study suggested that breeds of cattle in the present study had potential for production of good meat yield; tender beef and healthy beef that can satisfy the demand by local and export market there by enhance the livelihood of farmers and can boost national economy. Therefore, to identify the causes for low meat yield of all breeds, tough beef and variation observed in fatty acid concentaration, and to develop strategies aiming to increase meat yield or dressing percentage, evaluation of the three breeds finished under similar condition and molecular characterization for early age (<3 years) are recommended.