This study aimed to analyze ruminal fermentation, methane emissions, and methanogen levels for different forage feed type and concentrate feed ratios. Alfalfa hay, oat hay, and a feed concentrate were used for in vitro fermentation experiments, at ratios of 9:1, 5:5, and 1:9 (forage:concentrate). After 24 h of incubation, rumen fermentation and methanogen level changes were evaluated. In the low forage treatments, the total gas, CH4, NH3-N, true dry matter digestibility, and total volatile fatty acid were higher than the other treatments, which were used as the parameters on which to assess rumen fermentation (P < 0.05). The feed ratio influenced the copy number for the total archaea and the genus Methanobrevibacter (P = 0.015, P = 0.010). The copy number result trend was like that for CH4 per digested dry matter (DDM). The PCR results and methanogen copy number analysis indicated that the composition of the methanogens affected the CH4 levels, not their copy number. The results of this study can be applied to predict rumen fermentation and methane emission patterns for cattle fed a variety of feedstuffs.

This study was conducted to improve growth performance of Hanwoo heifer and to produce high quality of meat with dietary means during growing and early fattening period. Particularly, additional energy diet to relieve estrus stress was main purpose in this study. The results of in vitro rumen fermentation indicated that there was no negative effect by additional energy diet as treatments. In the feeding trial, twenty Hanwoo heifers(average 10 months age) were allocated and distributed into two treatments in randomized block design based on body weight. There were three growth stages such as growing, early fattening and late fattening periods in this feeding program, respectively. In growing stage, there were two treatments consisting of only total mixed ration(TMR) as a control and TMR with additional energy treatment. The experimental diets were fed twice a day, and water and mineral were freely accessed. In additional energy treatment, 500 g of concentrate diet was fed daily to relieve estrus stress due to obese with high energy intake. Not outstandingly differences were found across the treatments during entiretrial period. While, unexpectedly greater feed conversion ratio in treatment compared to the control was found during late fattening period. It seems that the blood cortisol decreased with addition energy supplementation compared with the control during trail period. Carcass characteristics including carcass weight, back fat thickness, marbling score, meat color, fat color, maturity and texture were not significantly different each other. Rib-eye area, however, was greater in the control compared to the treatment(p<0.05). In addition, it appears that yield index was tended to be greater in the control. In conclusion, it is suggested that additional energy supplementation to Hanwoo heifer could get a potential in improving meat quality and relieving estrus stress.

The present study was conducted to evaluate the effects of dietary formulated feed additive on growth performance and carcass traits of Hanwoo steers. A formulated feed additive reported to reduce heat load in the rumen in our previous research was used (Cho et al., 2014). Total 32 herds of Hanwoo steers were assigned into two groups of control and treatment. Total mixed ration was provided as basal diet for cattle and 100 g of additive was supplemented on diet for treatment. Feeding trial was performed during 120 days before slaughter. For growth performance, 3 periods (0~90 days; 90~120 days; 0~120 days) were allotted and average daily gain, feed requirement and final body weight were determined. Loin meat between 12th and 13th rib was used for meat quality analysis after slaughtering. Only 1st period showed significantly improved growth performance of treatment (P<0.05) and there were no significant difference in other periods. At 3rd periods (overall), a trend of increased average daily gain was found at treatment (P=0.075). Carcass performance and quality did not show significant differences between treatment and control (P>0.05). In meat quality, treatment showed significant increment in all measured meat colors (P<0.05) and significantly less sharing force compared to the control (P<0.05). Although no significant difference in growth performance and carcass yield were found, remarkably improved economic status was detected in treatment group. In conclusion, it could be suggested that application of a formulated feed additive specialized in reduction of heat load in the rumen was able to increase economical balance through enhancing heat stress condition of ruminant and growth.