| Abstract |
The obtained results could be summarized as follows:
1- The yield of forage and silage crop of single crosses increased by 10.77 and 10.55% compared to third crosses, respectively. Single cross Watanya-4 recorded the highest yield of forage and silage crop 7.27 and 6.94 ton DM/feddan, respectively). Single cross 10 recorded the highest yield of grain (2,55 ton DM/feddan), while third cross Pioneer-Dahab recorded the highest grain content (40.30%).
2- weight loss during ensiling was 0.20-0.37 ton DM / fed. Or 3.72-7.84% of forage yield, While ensiling losses as apercentage of weight loss re 62.65-78.84 % for soluble carbohydrates, 3.63-7.50 % for protein and 8.95-11.25 % for fiber.
3-The contents of OM and NFE increased and CP, CF, EE and ash decreased with increasing DM content. Also, the content of NFE increased with increasing grain content. Moreover, the contents of OM and NFE decreased and CP, CF, EE and ash increased after ensiling.
4- All corn variety and hybrids were agood quality silages except single cross 158, which had adark green color and sliminess texture.
Evaluation of silage quality should depend on the determination of various indices such as pH was 3.52-4.18 and the concentrations of lactic acid was 4.39-6.25 % of DM, TVFA's was 1.34-2.74 % of DM, total organic acids was 5.87-8.20 % of DM and NH3-N was 0.043-127% of DM or 3.61-9.06 % of total-N.
5- silage DM intake by sheep increased with increasing DM content which ranged from 985 to 1405 g/day.
6- Third cross Pioneer-Dahab had the highest digestion of DM (71.79% OM (73.28 %) and NFE (79.55 %) and subsequently the highest TDN value (72.54%), while third cross Neama-47 had the highest digestion of CP (70.08 %) and subsequently the highest DCP value 6.22%
7- The yield of TDN and DCP of single crosses increased by 9.82 and 7.04 % than those of third crosses. Single crosses Watanya-4 and 10 recorded the highest yield of 4.82 ton TDN and 353 kg DCP .
8- The output per feddan doubled 1.38 to 1.82 times when corn used as a silage compared with grain.
2- Performance of growing Friesian calves fed rations containing corn silage:
Twenty eight growing calves with average body weight of 176.68 kg and age of 8 months were divided randomly into for similar groups (seven for each group) according to live body weight and age.
Assigned randomly for the four experimental rations during the first (first 140 day of experiment) and second (from day 141 to rich 450 kg body weight) periods as follows:
R1:(control ration): 65% concentrate mixture + 15% fresh berseem (first period) or berseem hay (second period) + 20% rice straw.R2: 50% concentrate mixture + 50% corn silage.R3: 25% concentrate mixture + 75% corn silage.R4: 100% corn silage (first period) or 75% concentrate mixture + 25% corn silage (second period).
Eight digestible trails were conducted during the first and second periods to determine the digestibility coefficients and nutritive values of rim experimental rations by Friesian (three from each group) using acid insoluble ash as anatural marker.
Feed intake, rumen activity, blood constituents, nitrogen balance, live body weight gain, feed efficiency and economic evaluation were also studied during the feeding trials. At the end of experiment, three calves from each group were slaughtered to determine carcass characteristics.
The obtained results could be summarized as follows:
1-The contents of DM, CP, EE and ash increased with increasing the level of concentrate mixture, which control ration had the highest contents of DM, CP and ash and R2 had the highest content of EE.
While the contents of OM, CF and NFE increased with increasing the level of corn silage in the rations, which all corn silage ration had the highest contents of OM, CF and NFE.
2- The digestion coefficients of DM, OM, CF and NFE by Friesian calves and subsequently TDN value increased significantly (P<0.05)
with increasing the level of corn silage in the rations up to 75%, which calves fed R3 recorded the highest digestions of DM, OM and NFE and TDN value. While the digestion coefficients of CP and EE and
subsequently DCP value increased significantly (P<0.05) with increasing the level of concentrate mixture in the rations; which calves fed control ration recorded the highest digestion of CP and TDN value and those fed R2 had the highest digestion of EE.
3- Friesian calves fed R4 recorded significantly the least intakes of DM, TDN, CP and DCP than those fed the other rations.
4- Nitrogen balance as apercentage of nitrogen intake or digested increased significantly (P<0.05) with increasing the level of corn silage in the rations up to 75%, which calves fed R3 recorded the highest values (53.71 or 83.69 %, respectively).
5- Ruminal pH value increased, while ammonia nitrogen and total volatile fatty acids decreased significantly (P<0.05) with increasing the level of corn silage and decreasing the level of concentrate mixture in the rations, which R4 recorded the highest pH value and the least concentrations ofNH3-N and TVFA's.
6- Calves fed R4 had the highest concentration of hemoglobin and those fed R3 had the highest concentrations of total lipids and cholesterol. While calves fed control ration had the highest concentrations of total protein, albumin, globulin, urea-N, creatinine, GOT and GPT.
7- Average daily gain of calves fed 100 % corn silage ration (0.40 kg) was lower significantly (P<0.05) than those of calves fed Rl, R2 and R3 (1.24, 1.21 and 1.14 kg, respectively).
8- Friesian calves fed R4 (all silage ration) recorded the least feed and economic efficiency, while those fed R3 recorded the highest feed and economiceficiency.
1- Control ration had the highest contents of DM, CP, EE and ash; R3 had the highest contents of OM and NFE and R4 had the highest contents of CP and EE.
2- The highest digestion coefficients of DM,OM, CF and NFE and TDN value were recorded by calves R3,while the highest digestion coefficients of CP and EE and DCP value were recorded by Friesian calves R4 and those fed Rl recorded the highest digestion coefficient of CF
3- Friesian calves fed control ration (Rl) recorded the highest intakes, while those fed R4 recorded the least intakes of DM and TDN and those fed R3 recorded the least intakes of CP and DCP.
4-Nitrogen balance as apercentage of nitrogen intake or digested increased significantly (P<0.05) with increasing the level of corn silage in the rations, which calves fed R3 recorded the highest values (47.14 or 77.20 %, respectively).
5-Ruminal PH value increased, while ammonia nitrogen and total volatile fatty acids decreased significantly (P<0.05) with increasing the level of com silage, which calves fed R3 recorded the highest Ph value and the least concentrations ofNH3-N and TVFA's.
6- Calves fed R3 had the highest concentrations of hemoglobin,total and cholesterol.While calves fed R4 had the highest concentrations of glucose, total protein,albumin,globulin,urea-N,creatinine,GOT and GPT.
7-Calves fed R3 had the highest daily gain(1.36 kg), while those fed control ration had the least gain 0.89
8- Friesian calves fed R3 (25% concentrate mixture + 75% com silage)
recorded the highest feed and economic efficiency, while those fed control ration recorded the least feed and economic efficiency.
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