Effect Of Honeysuckle Extract On Skeletal Muscle Morphology And Meat Quality In Beef Cattle Under Hot Environment

High temperature and humidity environment in summer induced heat stress of beef cattle, which decreased the slaughter performance and meat quality. It is a key problem that how to improve meat quality of beef production in summer. Honeysuckle extract such as flavones and chlorogenic acid play a role in antioxidation and against oxidative damage on animals. The main purpose of this experiment is to study the effect of honeysuckle extract as feed additives on skeletal muscle morphological structure and meat quality of beef cattle under hot environment. The study was divided into three experiments as follows.The first experiment: This study was conducted to investigate the effect of honeysuckle extract on the antioxidant function and skeletal muscle morphological structure of beef cattle under hot environment. 15 Jinjiang yellow cattle with 360±20kg were randomly divided into 3 treatment group, each group of 5. cattle in normal temperature group were fed under the appropriate temperature in spring(THI<72), and others were fed under high temperature group in summer(THI>79). Cattle in honeysuckle group were fed Ponnisetum hydridumor and concentrate feed with honeysuckle extract by0.2%, but cattle in others were only fed Ponnisetum hydridumor and concentrate feed.During the trials, the temperature and relative humidity in the house of beef cattle were observed. Body temperature, respiratory frequency and serum endocrine hormone levels,antioxidase activity of experimental cattle was determined on the day of 20, 40 and 60, and at the end of this trail, all experimental cattle were slaughtered and their longissimus muscle morphosis were measured. The results showed that high temperature and humidity environment in summer caused a high heat stress of beef cattle. Body temperature,respiratory frequency and serum COR levels in high temperature group were higher than those in normal group. Serum T3 and T4 content of beef cattle in high temperature were lower than normal. High temperature stress decreased serum LDH and CK activity and declined antioxidase activity in beef. However, comparing with high temperature group,the activity of serum CK with the honeysuckle extract group were decreased by 105.09%(P<0.05), but the activity of T-AOC and the length of skeletal muscl segment were increased by 59.74% and 13.16%(P<0.05). Muscle morphosis damaged were restored to normal. These results indicated that high temperature and humidity environment induced the thermal stress reaction of beef cattle, and high temperature stress enhanced the body temperature, respiratory frequency and blood cortisol levels of beef, and decreased their contents of serum T3 and T4 levels. However, dietary supplemental with honeysuckle extract improved the antioxidant and restored the morphosis of muscle damaged, and relieved the stress response of beef cattle under hot environment.The second experiment: Muscle fibers is an important part of the skeletal muscle,normal muscle morphosis are related to meat tenderness and water-holding capacity. Thisstudy was conducted to investigate the effects of honeysuckle extract on meat quality in beef cattle under high temperature. The experimental animals and groups are the same as the first part. The results showed that 1) Meat quality: comparing with normal temperature group, high temperature environment increased the shear force values and drip loss of beef,but decreased a* values of longissimus muscle. The shear force values with honeysuckle extract group were declined by 8.73% and 19.68%(P<0.05), and the drip loss in honeysuckle group were decreased by 12.93% and 23.10%(P<0.05) at 45 min and 7d comparing with the high temperature group,but no difference was noticed about a* and b*values of longissimus muscle. 2) Fatty acid composition: the contents of C14:1, C16:1 and C17:1 with the high temperature group were higher than those in the normal temperature group, and especially the rate of n-6 and n-3 were increased by 38.05% comparing with the normal. Moreover, the contents of C10:0 and C12:0 with honeysuckle extract group were higher than those in the normal temperature group, and the levels of C14:1and C16:1 were increased by 122.50% and 77.49%(P<0.05) comparing with the normal. 2) Amino acid composition: comparing with the normal temperature goup, the contents of glutamic acid,phenylalanine, total amino acids and essential amino acids of the high temperature group were declined, but no changes about other amino acids. The contents of glutamic acid with honeysuckle extract group were higher by 18.73%(P<0.05) but glycine content were lower by 27.08%(P<0.05) than that of the high temperature group.These results indicated that high temperature stress induced their meat quality worse, but dietary supplemental with honeysuckle extract enhanced beef tenderness and color, and increased the contents of monounsaturated fatty acid and glutamic acid, and improved meat flavor and quality.The third experiment: The expression levels of calcium protease system have an important influence on beef tenderness. To study the effect of honeysuckle extract on the m RNA and protein expression of calpain and calpastatin of beef cattle under hot environment. The results show that the activity of Ca-ATPase in longissimus muscle were declined, but the m RNA expression of calpain1 and calpain 2 were increased comparing with normal temperature. No difference was noticed on the contents of calpain1,calpain 2and calpastatin of longissimus muscle between the normal temperature and high temperature group. However, comparing with high temperature group, the activity of Ca-ATPase were increased by 36.11%(P<0.05), but the gene expression of beef calpastatin were declined by 23.00%(P>0.05) with honeysuckle extract group. No difference was noticed on the m RNA expression and protein levels of calpain 1 and calpain2. These results indicated that high temperature stress declined the activity of Ca-ATPase in longissimus muscle, but did not influence the expression of calpain1,calpain 2 and calpastatin of longissimus muscle. Dietary supplemental with honeysuckle extract enhanced the activity of Ca-ATPase, and decreased the m RNA expression of beef calpastatin.