Eighteen crossbreed Friesian cows in the 2"4_3<11 season of lactation and
weighing an average of 450 Kg in their early lactation stage were assigned to three
balanced groups according to body weight and milk yield (six animals each). The first
group was received a diet containing concentrate feed mixture (CFM) + silage with
molasses + rice straw. 2nd ,iroup < /sup> received a diet containing CFM + silage with yellow
com + rice straw and the 3 group received a diet containing CFM + silage with chips
of sweet potato + rice straw. The diets were formulated to be iso-caloric and rso-
nitrogenous according to NRC (1988).
The tests 0 f silages indicate that, pH values, NFA's, lactic acid and NH3-N
concentrations were in normal values and could be classified as good quality silage.
Intake of CFM, RS, silages and total dry matter k glh/d 0 f cows was nearly similar
among tested groups. The highest (P<0.05) digestibility values of all nutrients were
shown when feed BS-Y and BS-P, while the values of ration containing BS-M
appeared to be the lowest. Similar trend was noticed for the NOF, hemicellulose and
TON values of experimental rations. However, no significant difference was detected
among different experimental rations for ADF and ADL digestibility.
No Significant effects on ruminal pH values among different experimental
rations were observed. Concentrations of NFA's were significantly differed with
feeding BS-P and BS-Y compared with feeding BS-M. The overall mean values of
acetic, propionic, butyric, ISO-butyric and valeric acid ware not affected significantly
when feeding different types of berseem silage. On the other hand, proportions of iso-
valeric acid increased with feeding BS-Y and BS·P compared with feeding BS-M. The
overall mean of total nitrogen (TN) was significantly higher (P and BS·P than those of BS-M silages. However, the values of NPN and NHJ were
taken the reflected trend with feeding BS-Y and BS-P compared to BS-M. The true
protein nitrogen (TPN) was Significantly decreased when fed BS-M compared with
either BS-P or 8S- Y at different times and also with overall mean. The microbial
protein nitrogen (MPN) was decreased only after feeding BS-Y, however no Significant
(P experimental diets in this respect.
Plasma constituents were increased (P< 0.05) for total protein and glucose with
added 8S-Y and BS-P compared to BS-M group. Feeding 8S-M, 8S-Y or BS-P had
no significant effects on the albumin, globulin albumin/globulin ratio. It is interest to
observe that, feeding BS-P and BS- Y decreased significantly (P<0.05) urea nitrogen,
aniline transaminase (AL T) and aspartate transaminase (AST) in' serum compared
with feeding BS-M. Milk production and fat corrected milk were increased significantly
(P<0.05) when feeding BS-P and BS-Y compared to BS-M. However. fat, protein,
lactose, total solid and solid not fat were not significantly differed among experimental
tested groups.
In conclusion, these results indicated that added sweet potato tubers compared
to use of either corn and EI-Mufeed as sources of energy for making berseem silage
could improve silage quality and could narrow the gap between caloric and protein
ratio. Also such situation could improve feed efficiency for lactating cows.