The present study was conducted to examine the effects of different plant oils or plant oil mixtures and high-temperature, microtime processing (HTMT) on the CLA content in Hanwoo steers. Experiment 1, consisting of 3 in vitro trials, was conducted to determine how the biohydrogenation of C18 fatty acids and CLA production were affected by fat sources (tallow, soybean oil, linseed oil, or mixtures of soybean oil and linseed oil) or HTMT treatment in the rumen fluid. The results showed that HTMT was capable of protecting unsaturated fatty acids from biohydrogenation by ruminal bacteria. The HTMT-treated diet containing 4% linseed oil (LU) and a supplement containing 2% linseed oil and 1% soybean oil treated with HTMT + 1% soybean oil (L(2)S(1)U+S(1)) produced an increased quantity of trans-11 C18:1 and cis-9, trans-11 CLA, and a reduced quantity of trans-10, cis-12 CLA. Based on these results, in vivo studies (Exp. 2) were conducted with LU and L(2)S(1)U+S(1). These 2 treatments increased the content of cis-9, trans-11 CLA in LM compared with the control diet. The content of trans-10, cis-12 CLA in subcutaneous fat was also increased in the L(2)S(1)U+S(1) treatment compared with other treatments. The subcutaneous fat thickness in the LU treatment was decreased compared with the L(2)S(1)U+S(1) treatment. The LU treatment significantly decreased fatty acid synthase expression but simultaneously increased leptin expression. In this report, we showed that diets containing LU and L(2)S(1)U+S(1) were capable of increasing CLA in the intramuscular fat of beef.

The present study was conducted to examine the effect of a stair-stepped feed intake pattern on growth, feed efficiency, and meat quality of Hanwoo steers. Twenty-seven 11-month-old Hanwoo steers were randomly divided into three groups. The control group was fed according to the Korean steer feeding program, and the other two groups were fed according to an alternated feeding schedule of 3-2-4-2 months. During the first three months of the experiment, treatment group 1 (T1) and treatment group 2 (T2) were fed 20% and 30% less than the control group, respectively. For the following two months, the T1 group was fed 20% more than the control group while the T2 group was fed 20% less than the control group. In the third step, T1 and T2 groups were fed 20% and 10% less, respectively, than the control group for four months. In the last two months, T1 and T2 groups were fed 20% more than the control group. After the stair-step feeding trial, steers were fed concentrated feed ad libitum for five months. The altered feed intake pattern did not affect daily body weight gain. However, daily feed intake tended to decrease and growth efficiency tended to increase in the two treatment groups compared to the control group. Altered feed intake also affected blood metabolite levels. The serum glucose and BUN level of the T1 group increased in the first re-fed period compared to the T2 and control groups. The serum cholesterol level of the T2 group decreased in the first restricted-re-fed growth period compared to the T1 and control groups. The serum NEFA levels of the two treatment groups increased from the first restricted period compared to the controls. The serum insulin level of the T2 group increased in the last period compared to the T1 and control groups. Regarding meat yield index, the control group was significantly higher than the T2 group (p<0.05). Regarding meat yield grade, the carcass back fat thickness of the T2 group was significantly higher than the control group (p<0.05). In marbling score, the T1 group was the highest (4.9), followed by the control group (4.1) and the T2 group (4.0). These results indicate that using a stair-stepped growth pattern (T1) can contribute to improvements in growth efficiency and muscle marbling.