A study was conducted to evaluate the effect of age and breeds (Arsi, Borana, HF-Cross and Harar) on carcass and meat characteristics of bulls finished under similar feeding conditions. The feeding experiment was conducted for 90 days at Beef farm of Haramaya University. In this experiment, 24 bulls were fed with roughage (60%) which contained grass hay and wheat straw and concentrate (40%) which contained wheat bran, noug (gucia abysica) cake, maize grain, limestone, salt and ruminant premix. The bulls were transported to Bishoftu ELFORA export abattoir for slaughter following the procedure of the abattoir. The result of the study revealed that the average slaughter weight, hot carcass weight, cold carcass weight, shrink loss, commercial dressing and true dressing percentage were 179.1 kg, 86.8 kg, 82.7 kg 4.7%, 48.8% and 78.3%, respectively. Total edible and nonedible offal were significantly (P < 0.01) influenced by breed and age. Pelvic fat was significantly (P < 0.01) influenced by breeds. Meat yield percentages of Arsi, Boran, Harar, and HF-crossbred were 78.1%, 77%, 72.8% and 77.2% respectively. Meat yield was predicted from fat thickness and ribeye area with 61% accuracy. Arsi bulls attained the highest (78%) meat yield at early age but decreased by 0.713 rate as age of animals advanced by one digit whereas the meat yield from other breeds showed increment in meat yield percentage with the rate of 1.98, 1.1 and 0.1 for cross, Borana and Harar breed bulls, respectively as age advanced.

Understanding the interaction of livestock production and climate change is currently the main issue in global warming. This paper reviews the contribution of livestock production in greenhouse gas emission and its mitigation strategies. The potential contribution of individual large ruminants are 200-500 litters of methane per day while small ruminants produces 20-40 litters of methane per day. The major greenhouse gas related to livestock production are methane and nitrous oxide which contribute approximately about 14.5% global GHG emissions. Limiting emissions from livestock, without compromising food security, is an important limit greenhouse gas emissions. The main choices for reducing greenhouse gas emission in livestock production are more related to improving animal production. Mitigating emission of CH4 by means of improved management of biogas and manure, reducing CH4 emission from enteric fermentation through improved efficiency and diet, husbandry as well as genetic management are some of strategies used in mitigating enteric emission of methane from livestock. The other one is mitigating emission of nitrous oxide through more efficient use of nitrous fertilizer, proper manure management and by using different feed additives.

It is easy to anticipate that most production of tropical livestock production and productivities are declined when the climate condition is not comfortable. On the other hand, global demand for livestock product is expected to increasing in the future due to human population and the need for animal protein is increasing. Therefore, this review was show the prospect of climate change on livestock production. It is obvious that there is an interaction between livestock production and climate change. Therefore, The potential impacts of climate change on livestock in the future will result in negative changes in production and quality of feed crop and forage, reduced water availability and quality that may affect the hygienic quality of their products, reduced meat, milk and egg production, change in diseases situation in terms of distribution and occurrence, reproduction problem and biodiversity loss.

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Background: The study was conducted to evaluate the fattening performance of Arsi, Borana, Harar and Holstein Friesian crossbred bulls finished under similar feeding condition at the beef farm in Haramaya University. A total of 24 bulls with age categories of 2–3 and 4–5 years were used in the complete block design for the experiment. Total mixed ration was provided at 3% of their body weight during experimental periods.Results: The average daily weight gain of the four breeds range from 0.49 to 0.71 kg. Feed conversion efficiency also ranges from 0.11–0.15. Simple linear regression models were used to explore the relationship between live body weight change and change in body condition score as well as seven linear body measurements for all age groups. An average change for a unite of body condition score was equivalent to 20.3, 20.61, 22.42 and 27.78kg for Borana, Arsi, Harar and Holstein Friesian crossbred bulls respectively. Body condition score was significantly influenced by breeds. There was a significant breed by age interaction effect on the initial body condition score of the four breeds. There was a significant and positive strong association between change in body weight and body condition score. There was a significant and strong correlation between change in body weight and change in Total topline, neck length, heart girth, flank circumference and rump length having correlation coefficient ranges from 0.57 to 0.97. Higher net profit of 7,380.47 ETB per head was recorded by Borana bulls followed by Harar bulls, Arsi and Holstein Friesian crossbred with net profit of 5,406.86, 5193.29 and 3,384.98 ETB per head respectively.Conclusion: Borana bulls are more superior in weight gain and net profite. Body weight change could be predicted based on body condition score change during fattening period.