الفهرس 
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Abstract
The main objective of this study was to achieve dairy farming sustainability by increasing corn silage level to decrees feeding cost and increasing level of vitamin E & selenium to enhance milk quality and safety. This study included three experiments the first one was the In vitro experiment were conducted in Regional Center for Food and Feed lab, Giza Governorate, Egypt in March, 2017, where the second one was In sacco experiment were conducted in King Marriott Research farm according to Desert Research Center located in Alexandria Governorate, Egypt in April, 2017 and the third experiment was In vivo trial were conducted in Al-Salhia Dairy Farm Company, farm two located in El-Salhia City, Sharkia Governorate, Egypt for 12 week, during May and July, 2017.
The objective of the first experiment was to evaluate the nutritional value of different silage samples from different location around the country by In vitro method, while the second experiment was to evaluate the nutritional value of silage samples using In sacco method and the last one was to reduce feed cost of dairy ration and increase milk quality & safety.
First experiment
Samples of silage were collected from four cites El-Nobaria, Janaklise, El-Salhia and El- Monofia. Silage chemical composition were analyzed for DM, OM, CP, EE, CF, ASH , ADF , NDF, cellulose, hemicellulose, lignin, growth energy and TDN were calculated , also fluids of silage samples were collected to measure rumen pH , ruminal ammonia concentration (NH3N) and total volatile fatty acids (VFA’s) to searching for the best nutritive values of the best corn silage sample.
Forage samples were incubated In vitro in rumen fluid in calibrated glass syringes. The syringes were incubated in a water bath at 39°C. To readings gas production after 0, 2, 4, 8, 16, 24 and 48 hours of incubation.
Second experiment
A study of artificial fiber bag technique were conducted using three mature Barki sheep about 60 kg and one year old. Each animal was fitted with a rumen cannula (40 mm in diameter) to determine the DM disappearance for corn silage samples in the rumen. The bags used in this experiment were mad of dacron material, the number of holes per cm was about 1940, the bags were made to assize of 8*5 cm. 5-gram samples dried and milled through a 3-mm sieve were weighed into nylon bags and incubated in the three rumen fistulated sheep for 2, 4, 8, 12 and 24 h. DM losses for each incubation time were determined.
Third experiment
The third study included three groups of Holstein lactating cows, control group (LSLF, low supplement (Se & Vitamin E) and low forage (silage)), High supplement low forage group (HSLF) and High supplement (Se & Vitamin E) High forage group (HSHF) .The changes in Actual milk yield, milk composition, milk quality milk safety, feed conversion efficiency and blood profile were determined in all groups. 98 Holstein lactating cows were used 33 for LSLF group, 32 for HSLF group and 33 for HSHF group. LSLF group is the control or farm ration group, HSLF group fed control ration of LSLF plus 50% over the requirement of NRC (2001) of selenium & vitamin E and HSHF group fed high level of corn silage and Selenium & vitamin E.
The results are summarized as follows:
The First experiment
Under the conditions of this experiment, the obtained results indicated that the chemical composition, characteristics of tested silage flued and In vitro study indicated that the best sample were El-Salhia sample
The Second experiment
Under the conditions of this experiment, the obtained results indicated that the higher total accumulated gas after 48 hour for different silage samples were 166 ml/g DM for El-Salhia sample , also the higher ME (Mcal/Kg DM) and SCFA (mmol /g DM) were 1.60 and 0.659 for El-Salhia sample also the highest degradation rate was recorded for El-Salhya sample. Ruminal kinetic parameters of different silage samples showed that the soluble fraction (a) were El-Salhia sample is the highest one, were the highest degradable fraction (b) is El-Nobaria sample. The un-degradable fraction (U) were the lowest one were El-Salhia silage sampleand the effective degradable dry matter (Eddm) was the same for all samples at 2% passage rate of maize silage.
According to the previous result the best silage sample was El-Salhia because its chemical composition values were the best one ( DM, OM, CF, NDF, CP , GE ), good quality characteristics sample ( PH, NH3-N – Ammonia ) , In vitro evaluation ( gas production , ME , SCFA), In sacco evaluation (Extant DMD, degradation rate ) so we decide using El-Salhia silage in the farm (third) experiment
Third experiment (In vivo farm experiment)
Under the conditions of this experiment, the obtained results indicated that increasing corn silage percent on DM basis resulted in significant increasing in milk fat while not affect significantly protein, lactose, ash and TS contents. The data showed slightly increase in MYfor HSHF compared to HSLF and LSLF. On the other hand there were significant increase in 4% FCMY and ECMY for HSHF compared to HSLF and LSLF. HSHF recorded for significant higher fat% and there is no significant differences between groups in protein total solid % ash and lactose.
Data showed the effect of increasing corn silage in lactating ration and Se &vitamin E supplementation on milk quality and safety, milk content from vitamin E and selenium as well as increase glutathione peroxidase activity for HSHF and HSLF compared to LSLF. Also increase corn silage percentage in the animal ration resulted in slightly increase in vitamin E , selenium and glutathione peroxidase activity compared to ration content lower percent of corn silage. The data clearly showed that significant decrease in sodium (Na+) content in milk for HSLF and HSHF compared to LSLF. Also vitamin E and selenium supplementation resulted in decrease potassium (K+) concentration for HSLF and HSHF compared to LSLF but the differences but the between, HSLF and HSHF were not significant. Also decrease total bacterial count and electrical conductivity for the supplemented group compared to unsupplemented.
Data showed that there were significant decrees in DMI/MY, DMI/FCMY4% and DMI/ECMY for HSHF. HSHF is more efficiency to convert TDNI to MY, FCMY and ECMY while HSLF more efficiency than LSLF. There is no significant difference between groups to convert CPI to MY. CPI/FCMY and CPI/ECMY were more significant efficiency for HSHF compared with HSLF and LSLF also PROT. EFF.(%) and Eng. Eff (M cal/l) were significant increase for HSHF compared HSLF and LSLF.
Liver function parameters were in normal range for all groups and no significant differences between them. No significant differences between groups in Kidney function parameters and all of them within normal range. Immunity parameters within normal rang for all groups and there were the most significant increase in GPx for HSHF compared with other groups and there is no significant difference between groups in selenium level
Data showed that using high corn silage ration plus high level of vitamin E and Se achieve more economic efficiency (43.61%) for HSHF group compared with control ration (LSLF) group (36.94) and 36.79% for HSLF group.