Application Of Phytosterols And Its Mechanisms In Dairy Cows

The present study was conducted to investigate the effects of phytosterols on rumen fermentation, milk production and blood components to estimate the possibility of phytosterols being used on dairy cow.Experiment one:The present study was conducted to investigate the effect of phytosterols on rumen fermentation in vitro. The phytosterols were added at levels of 0.1, 3 and 6μg and dissolved in 6ml ethyl acetate (8.3%) against 200 mg mixture common diet in rumen fluid. In vitro gas production (GP) was recorded at 3.6,12.18 and 24 h incubation. The incubation was stopped at 6h,12h and 24h and then the inoculants were determined for rumen fermentation parameters. The GP in treatments was higher than control all the time and was 41.13 ml.39.83 ml,44.5ml at 24h. The pH of ruminal fluid was slightly lower, but all values were in the normal range. The content of lactate and ammonia-N in treatmentⅢat 12h and 24h and ammonia-N in treatmentⅡat 24h was significant lower than the control (P<0.05). That DMD in treatments was 37.45%,41.60%, 45.62% was significant higher than the control (P<0.05). The content of MCP at 6h which kept little changes from that of the control, but treatmentⅢwas significant higher than the control (P<0.01). All VFAs had increase tendency obviously as rumen fermentation continue. It is suggested that with lower level of phytosterols could modify the rumen fermentation which was profitable on improving nutrient utilization and animal health. The group of adding 6μg is more obvious.Experiment two:Thirty-three Chinese-Holstein cows entered the study. The cows were divided into 3 groups (11 cows/treatment) according to the age. number of lactations, milk production and days in milk. The cows were fed a diet containing 0,200 and 800 mg/d of phytosterols. Total experiment lasted 63 days. Milk yield was recorded twice a week and milk samples from each lactating cow were taken at 1430h of midweek. Average milk production of the treatment cows were 1.71 kg/day and 0.44kg/day higher than that of the control. Milk fat content in treatments was 0.1 and 0.08 percent higher in treatment cows. A tendency of decreased milk protein, Lactose, non-fat solids, total solid percentage, and somatic cell count (SCC) were observed in the treatment cows, but the differences were not significant (P>0.05). Milk ketone (11.51mg/dl,10.70mg/dl) and milk urea nitrogen (MUN) (18.85 mg/dl,16.50 mg/dl) in treatments were decreased with the increasing level of phytosterols and the differences were significant between the control and treatment groups (P<0.05). It is suggested that with the inclusion of low level of phytosterols could balance energy and protein intake, keep the health and increase milk production of dairy cow. Supplementation of 200 mg phytosterols cow/day/cow? is more economic and effective.Experiment three:The design was the same as Experiment one and blood was taken by puncture in the jugular vein at 0830 h on Day 10.30 and 50 during the trial period. Blood plasma was collected for later analysis. Total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) in treatments had a decreased tendency comparing with that of control. The contents of total triglyceride (TG) and non-esterified fatty acid (NEFA) had increase tendency and decrease tendency as the experiment lasted, respectively, but the treatments were higher than the control. The content of 17(3-estradiol (E2) in treatments was higher than the control, except that treatmentⅡin Day 10 was significant higher than the control (P<0.05). There was little difference for growth hormone (GH) between treatments and control. Glutamic-oxalacetic transaminase (GOT) in the treatmentⅡwas higher than the control group on Day 10 (P<0.05), but all treatments was lower on Days 30 and 50. The content of superoxide dismutase activity (SOD) and glutamic oxalacetic transaminase (GSH-Px) except SOD in treatmentⅠat Day 10 was higher than the control. Malondialdehyde (MDA) was lower in the treatment groups than that of control all the time as the content being lowing, except that treatmentⅡwas significant lower than the control at Day 30 and Day 50 (P<0.05). It seems that phytosterols could decrease the activity of lipases. The activity lipoproteinesterase (LPL). hepatic lipase (HL) and total lipase (LA) was lower than the control except Day 30 (P<0.05). It is suggested that with the inclusion of low level of phytosterols could decrease cholesterol concentrations, balance energy and protein intake and remove spare free radicals of dairy cow. Supplementation of 200 mg phytosterols cow/day/cow is more economic and effective.