Evaluation of different feeding options on growth response and carcass characteristic of yearling Kereyu-Bulls to attain local/export market weight

The study was conducted at Adami Tulu agricultural research center on growth performance and carcass characteristics evaluation of one year old 24 Kereyu bulls. The objectives of the fattening trial were: to evaluate different feeds options on one year aged Kereyu bulls for them to attain 300kg export market weight gain, to evaluate the carcass characteristics of the animals under fattening and to identify the most economical feeding options to obtain the targeted export market weight gain. Three feeding treatments ( T1=Rhodes hay +20% molasses+ 40% wheat bran+ 40% Noug cake, T2 = Rhodes hay +20% maize grain+45% wheat bran+35% Noug cake and T3= Rhodes hay + 65% wheat bran+ 35% cotton seed cakes) were evaluated. Complete Randomized Block Design was implemented to assign nine Kereyu bulls to the three treatments. All the experimental bulls were supplemented with their respective feed rations at 2.5% of their body weight per day during the whole experimental period. The result of the fattening trials revealed that there is no signifi cant difference in daily weight gain, total weight gain, fi nal body weight and carcass characteristic of bulls received the three dietary feeds for 179 fattening days. Research Article Evaluation of different feeding options on growth response and carcass characteristic of yearling Kereyu-Bulls to attain local/export market weight Ashebir Worku*, Tesfaye Alemu, Mieso Gurru, Aman Gudeto, Firehiwot Messele and Genet Dadi Oromia Agricultural Research Institute; Adami Tulu Agricultural Research Center, Batu, Oromia, Ethiopia Received: 21 May, 2019 Accepted: 16 July, 2019 Published: 17 July, 2019 *Corresponding author: Ashebir Worku, Oromia Agricultural Research Institute; Adami Tulu Agricultural Research Center, Batu, Oromia, Ethiopia, E-mail:


Introduction
Ethiopia has the largest cattle population in Africa with an estimated 59.5 million heads of animals [1]. Cattle with their large number and diverse products contribute about 12% and 33% of the total and the agricultural GDPs, respectively. However, the earning from exporting of live animals and processed meat is very small as compared to the potential of the country. The average Ethiopian beef yield per animal of 135 kg is by far less than the 146 kg for Africa and 205 kg for the whole world [2][3][4].
Different feed options fed to cattle of different age groups for different length of fattening periods played a signifi cant role in bringing the animals to export market weight required. In addition to the effect of dietary feeds, various fi xed effects have their own role on growth performance and carcass characteristics of animals among these factors breed and age of the animals played an important role.
The effort made so far regarding fattening of beef cattle at different research centers less targeted the export market weight demand. Mainly they targeted domestic markets. To solve the underlying constraints different research proposals were developed by different agricultural research institutions in order to release feasible and promising fattening technologies for end users. To this end, previous studies [5][6][7], conducted to evaluate different feeding options on different cattle breeds of varied ages groups has played a vital role in improving the foreign currency earning the country can get from the sale of meat and live animal. Moreover, conducting such cattle fattening activities can bring a signifi cant change on income of the fatteners. Hence, this study on evaluation of feeding options for one year old Kereru bulls was developed to cover the following objectives.

Objective
To evaluate and identify the most economical feeding options for one year old Kereyu bulls fed on different feed options for the bulls to attain export market weight of 250 -300kg.
To evaluate the growth and carcass characteristics of Kereyu bulls.

Description of the study area
The experiment was conducted at Adami Tulu Agricultural Research Center, which is located in mid rift valley at 167 km from the capital city Addis Ababa, Ethiopia at an altitude of 1650 m above sea level. The agro ecological Zone of the area is semi-arid and sub humid with acacia woodland vegetation type. The mean annual rain fall of the area is 760 mm and its mean minimum and maximum temperatures are 12. 6 and 27 o C, respectively.

Experimental animals
For this experiment 24 one year old Kereyu bulls were purchased from Fantale market. The purchased bulls were transported to Adami Tulu agricultural research center and the animals were kept under quarantine in a separate barn and were treated against internal and external parasites before the commencement of the fattening trial. The animals were also vaccinated to control the most important diseases in the area.
The DM, total CP and TDN content of the feeds is depicted in table1.

Feeding the experimental animals
In addition to hay feeding, every day all the experimental bulls were supplemented with the above mentioned concentrate feeds at the rate of 2.5% of their body weight throughout the fattening period. This provision of concentrate was adjusted every two weeks depended on the weight change of the experimental bulls during the whole fattening period.
All experimental animals were individually fed their respective diet for the whole experimental period. The daily allocated feed was divided into two equal amounts to offer twice per day; half in the morning and half in the afternoon. Feeding of the experimental bulls was extended to 179 days until the bulls had attained, on average, the required export body weights of 250-300kg.
Average daily weight gain (ADG) of the bulls was calculated using the following formula.

Evaluation of carcass characteristics
At the end of the experimental period three fattened bulls were randomly selected from each treatment group and slaughtered at Adami Tulu Agricultural Research Center abattoir. Then the animals were skinned, all important internal organs such as kidney, heart, liver, lung, spleen, empty gut, heart fat, kidney fat, mesenteric and omental fat were eviscerated and the required carcass parameters were individually measured. The hot carcass were dissected symmetrically into right and left parts with the help of modern electrical carcass cutting machine and the weight of each part of the entire carcass was measured before the carcass was put into cold room at -4 o c for about 24 hours. After 24 hours stay, the cold carcasses parts were measured again to evaluate the difference in weight change between the hot and the cold carcass of each slaughtered animal. To evaluate the chilled carcass characteristics, the right parts of each slaughtered bull were cut into fi ve major carcass parameters.

Partial budget analysis
All costs incurred for fattening the experimental bulls using the three dietary feeds were recorded in order to calculate economic returns of fattening the bulls. Total variable costs incurred, such as animal purchase, transportation, feeds, labor and veterinary costs were collected. The gross output/revenues from the bulls were estimated at the end of the fattening period by the help of three persons who have enough knowledge on prices of fattened animals. Fixed costs incurred and the cost of grazing was not included in the analysis. Hence, this partial budget analysis indicates only gross margin of fattening bulls using the three different feed options.

Statistical analysis
Data of all live weights and carcass parameters were analyzed using the general linear model (GLM) of Statistical Analysis System [8]. The estimated least squares means were separated using the Duncan's Multiple Range Test at P< 0.05.

Effects of dietary feeds on weight gains
Least-square means (LSM) of fi nal body weight (FBW), total weight gain (TWG) and average daily weight gains (ADG)  [7], for two years-old Kereyu bulls and Tewodros et al., [9], for two years old Fogera bull fed with the same type of feeds.
The fi nal body weight attained in the present study was almost similar with what Tesfaye et al., [7], reported for two years-old Kereyu bulls fed on the same feeding options .
The daily weight gain (807.26 gm) of bulls fed on T3 is more or less similar with the fi nding of Tesfaye A.T., et al., [7], who reported the daily weight gain of 810 gm for two years old Kereyu bulls fed with similar ration. The one year old Kereyu bulls approached more or less the required 250 to 300 kg of export market weight demand at 179 days of feeding. This is duration is shorter when compared with the 224 fattening days taken by one year old Borana bulls to reach a 300 kg body weight [6]. On the other hand, the fi nal body weight of the one year old Kereyu bulls at 179 fattening days is similar with the FBW of attained by two years old Kereyu at 168 fattening days [7]. The trend of daily weight gain of each experimental bulls fed on three different feeds ration over the whole 179 fattening day is indicated in fi gure 1. The weight change of one year old Kereyu bulls were steadily decreased as the number of the fattening period is increased from 140 days to the end of the fattening periods. This result disagree with report of Mieso G., et al., [6], whom reported the ADG of one year old Borana bulls were decreased as the number of the fattening period is increased from 70 days.

Effects of dietary feeds on carcass components
The result of carcass evaluation of the bulls fed on the three different feed options is shown in table 3. As the result reveals the carcass composition of the experimental bulls fed on different feed options did not vary statically. However experimental bulls fed T3 registered higher SWT, HCW, and lower Bone, lean and Fat parameters when compare to bulls fed on T1 and T2. Animals fed on T3 (Rhodes hay + 65%wheat bran+ 35% cotton seed cakes) had lower fat composition than animals fed on the other two treatments. This result is similar with the fi nding of Mieso et al., [6], who indicated the absence of signifi cant difference in carcass components among yearling Borana bulls The bone, fat and muscle ratios of the bulls fattened for 179 days on the three different feeds option is indicated in fi gure 2.

Dietary effect on non-edible parts (Offals)
Even if slight variations were observed among bulls fed different rations in some non-edible parts; there were no signifi cant differences in all of the offal measurements among the bulls. This is indicated in

Economic return on fattening of one year old Kereyu bulls
The result of partial budget analysis of fattening the one year old Kereyu bulls fed on the three different feeds for 179 days is indicated in table 5. The results showed that experimental bulls fed on T1 had higher gross margin per animal (4813.00) than bulls fed on T2 (4521.23) and T3 (3638.30). Feeding with T3 is found to be less profi table as compare to feeding with       were provided for all of the experimental animals. Economic analysis of the different dietary treatment groups showed that, all the three feeding options are profi table for fattening growing Kereyu bulls and to obtain the required export market weight. Therefore, cattle fatteners can use one of the three feed options, depending on availability and accessibility of the feeds, for fattening one year old Kereyu bulls for export/local markets as the animals could attain the required weight of 250-300kg within 179 days of feeding.