Twelf lactating Friesian cows at 6 weeks of lactation period with an average
body weight of 450 ! 0.17 kg, in the 2nd to the 4th lactation were used in complete
switch-back design and divided randomly into four similar groups according to body
weight, milk yield and number of lactations (3 cows in each). Cows in the first group
were fed a control ration (R1) that consisted of 60% concentrate feed mixture (CFM),
15% rice straw (RS) and 25% berseem hay (BH). The other three groups were fed
rations which consisted of 50% CFM, 15% RS and 35% from both berseem silage
(BS) and orange waste silage (OWS) at different ratios, 75:25 for the second group
(R2), 50:50 for the third group (R3) and 25:75 for the forth group (R4). Contents of
CP, CF and ash were lower, while EE and NFE contents were higher in OWS
compared with BS. Contents of CP, CF and ash increased, while OM, EE and NFE
contents decreased with increasing level of BS and decreasing level of OWS in the
rations. Cows fed R3 recorded significantly (P<0.05) the highest digestibility
coefficients of OM, OM, CF, EE and NFE and subsequently TON and ME values.
While, cows fed R2 had significantly (P<0.05) the highest digestibility coefficient of CP
and subsequently OCP value. Cows fed R1 showed the highest intake of CFM, RS,
OM, TON, ME and CP compared with the other silage groups. While, cows fed R2 had
significantly (P<0.05) the highest intake of OCP.
Ruminal pH values were nearly similar for different experimental groups.
Cows fed R3 recorded the highest ruminal TVFA's concentration (P<0.05). While,
NH3-N concentration in rumen liquor inecreased significantly (P<0.05) with increasing
level of BS and decreasing level of OWS in the rations. Concentrations of total
protein, albumin, globulin and creatinine significantly (P activities of GOT and GPT significantly (P<0.05) decreased with increasing level of BS
and decreasing level of OWS in the rations. Cows fed R3 recorded significantly
(P<0.05) the highest yield of actual milk, 4% FCM and milk contents followed by cows
fed R2. Cows fed the control ration recorded significantly (P<0.05) the highest fat and
lactose contents in milk and those fed R3 had the highest total solids content
(P<0.05). While, there were no Significant differences in protein, solids not fat and ash
contents among the experimental groups. Cows fed R3 showed the highest feed and
economic efficiencies, while those fed the control ration had the lowest values
(P<0.05).