الفهرس 
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Abstract
The current study was carried out at the Farm of Animal Production Department, Faculty of Agriculture, Ain Shams University, Shoubra El-kheima,Qalubia Governorate, and all chemical analysis were performed in the laboratories of the Animal Production Department, Faculty of Agriculture, Ain Shams University, Shoubra El-kheima,Qalubia Governorate, Egypt
The first experiment comprised as In vitro trial which used for evaluated diets containing different levels of cobalt whether inorganic or nano particles.
The second experiment comprised of three dietary treatments which used for evaluated the diets containing two different sources of cobalt (inorganic and nano) comparing with the control group without addilive.
Experimental design.
First experiment (In vitro gas production)
First experiment comprised by In-vitro trial that was used different cobalt levels 25, 50, 75, 100 and 125% of requirements of goat and sheep allowance according to NRC, (1985). These levels were tested as cobalt oxid compound in two pictures, inorganic or nano particle size for digestibility in laboratory tubes.
Second experiment: (feeding and metabolic experiment)
Twelve animals were used from Zaraiby goats. The experiment lasted for 60 days. The average initial animals’ weights were 10.71±0.23 kg and the age of the animals ranged from 5 to 6 months. Goats were weighed during the experiment every week before the morning meal to estimate average daily gain (ADG). Feeding requirements were adjusted biweekly according to weight changes.
Results
In vitro gas production
Nutrient degrability:
The results of These treatments showed that, after 24 hours of incubation, a significant increase (P<0.05) in DM degradability was reported for nanocobalt supplemented rations at level of 50 and 75 %, while maximum DM degradability was reported for rations supplemented with 25 and 50 %of the inorganic cobalt requirement, respectively. A major impact of supplementation with cobalt nanoparticles 25 and 50 % on OM degradability. Levels of cobalt either in nanoparticles or inorganic above 50% of cobalt requirements led to a significant (P<0.05) decrease in the degradability of OM. The values of NDF,ADF and cellulose degradability were higher by coblt additive either in nanoparticles or inorganic at all levels compared to control ration without additive. While, degradability values of NDF,ADF and cellulose were decreased with inorganic cobalt ration and increased with nano cobalt above level of 25%.
Fermentation parameters and total gas production
The addition to the experimental ration of ascending cobalt nanoparticles had no major effect on pH value and the ME metabolizable energy (Mcal/g). Significant (p<0.05) increases in the concentration of ammonia (mg/100 ml) and TVFA’S (meq/100 ml) were increased at level of 25, 50 and 75 % compared to other levels in the cobalt nanoparticles supplementation. Nanocobalt addition increased ruminal bacterial growth ,their activities and increased protein degradation,. Ration supplemented with cobalt nanoparticles at level of 125 percent of the cobalt requirements improved microbial mass protein (MP) and microbial mass efficiency (EMP) compared with control and inorganic cobalt oxide supplementation.
Kinetics of nutrients gas production
The gas output per gram of DM, OM, NDF, ADF, hemicellulose and cellulose is shown after 24 hours of incubation, the gas was significantly (p<0.05) influenced by cobalt level being applied to the ration . Results indicated that there were substation decreased in gas production per gram of DM,OM,NDF,ADF and hemicellulose and increased in cellulose value compared to control The results showed that the addition of nanocobalt to the ration improves cellulolytic bacteria’s growth and may increase cellulose fermentation.
Results in In vitro gas production after 24 hours of incubation indicated that the values of DMD and OMD of nanocobalt addition were a significant increased (P<0.05) when levels were 50 and 75% compared with other additives of nano cobalt ,while the highest values of DMD and OMD were found with inorganic cobalt ration supplementation (25 and 50%). The nanocobalt additives had no effect on pH but more effect on ruminal ammonia and TVF’s values, as well as degradability of cell wall constituents and microbial protein production. The extent of gas production was high in control ration, adding cobalt (100 %) and nanocobalt (25% and 50%) than other adding levels. Microbial protein (M P) and efficiency microbial protein (EM P) recorded high values in all different (25,50, 75, 100 and 125%) added of nanocobalt compared to control (0%) and cobalt. Gas production degradability after 24 hours incubation DM, NDF, ADF, cellulose and hemicellulose of 25% nanocobalt recorded a significant increase (P<0.05) values compared to any adding nanocobalt or inorganic cobalt and control.
Second experiment: (feeding and metabolic experiment)
Feed Intake, total gain and ADG
No significant (P>0.05) difference was observed among experimental groups for DMI (kg/h/d) or CPI (g/h/d) values while, feed intake as DMI and CPI values tended to slightly increased with nanocobalt addition . However, there was a significant (p<0.05) difference in favor of the nanocobalt group , it was the highest in total gain , ADG; and, feed efficiency (kg gain/ kg DMI); followed by the inorganic cobalt group. However, using nano cobalt may have more beneficial effect in cobalt efficiency.
Digestibility and nutritive values
Nutrient’s digestibility values of DM, OM, CP, CF, NFE and NDF in the treatment of nanocobalt were higher (p<0.05) significantly than inorganic cobalt and control group. The same trend was observed with those percentages of ADF, hemicellulose and cellulose. It’s higher (P<0.05) significantly with nanocobalt than inorganic cobalt and control groups. The percentage of TDN was significantly (P<0.05) higher with nanocobalt groups than those others groups. But the value of nitrogen balance in goats’ diet with nanocobalt group was less than that in inorganic cobalt and control group. While the DE (Mcal/Kg DMI) value had no significant differences among groups.
Rumen parameters
The data showed that after 3 and 6 hours the pH value in control group and the inorganic cobalt groups more (P<0.05) increased than that in nanocobalt group. It observed that, there were natural decrease in the pH value occurred after 3 hrs.in all groups due to digestion operation. The results revealed that NH3-N values after 3 hours, there were no significant difference between control group and that inorganic cobalt group in NH3-N (mg/100ml) value, while, adding nanocobalt had lower significant (P>0.05) values of NH3-N than those others groups. However, after 6 hours, there weren’t (P>0.05) differences among experimental groups. It is naturally observed that NH3 values were in increased at 3 hrs, after feeding then decreased after 6hrs. Generally, data indicated that adding nanocobalt to goats’ diets resulted in depress of ammonia-N values either at 3h or 6h after feeding compared with control and inorganic cobalt groups. But the control group remained the highest among them. After 3 and 6 hours, value of TVFA’s of nanocobalt group was the significant lower level than other groups; the control group was the highest values, followed by the inorganic cobalt group., The TVFA’s values increased after 3hrs according to maximum level of feed digestion process, and then declined again due to many factors’ effects on level of TVFA’s in the rumen.
Blood parameters and body measurements
No significant differences were found at 0, 3hrs and 6 hrs. after feeding for all blood parameters, which indicated that there were no harmful effects on the animal’s vital organs and animal health. While, regards of comparative treatments, there were slightly (P<0.05) increasing of glucose, urea and total protein (TP) values as overall mean in nanocobalt additive then inorganic cobalt comparing with control group. In addition to, liver function as AST and ALT values were increased with adding cobalt whether inorganic or nanocobalt, however, The highest value found in nanocobalt group. Furthermore, they reported that the effect of adding nanocobalt particle on lamb’s liver function were similar to adding inorganic cobalt. That confirmed by the other data of growth performance and digestion coefficients where animal received nanocobalt additive have positive results revealed on body measurements.
It could be concluded that adding nanocobalt 25% from requearments of goats’ rations enhanced growth performance, digestibility coefficients, rumen parameters and slightly body measurements without any diverse effect on animals’ health