الفهرس 
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Abstract
This study was conducted at the Farm of Animal Production Department. Faculty of Agriculture, El-Minia University to estimate the convenient nutrient requirements of cow and Buffalo calves that Promote Favourable growth rate and carcass traits under the environment of EI-Minia Governorate. The effect of feeding level. sex, season of calving and stages of live body weight intervals on growth performance. The effect of feeding level and stages of live body weight intervals on blood constituents(Total protein, Total lipids and Cholesterol) of male Friesian and Buffalo calves were studied.
A total of 33 male calves (15 Buffalo and 18 Friesian) were slaughtered at 400-420 kg as average live body weight to examine the effect of feeding level, season of calving and slaughter age on carcass traits. The feeding value of feeds used in the feeding experiment were determined.
The results could be summarized as followes I. Growth performance
1.1. Daily gain:
Calves fed on 120 % level of feeding had the highest value of daily gain(0.59 and 0.53 kg/day). while calves fed on 80 % feeding level showed the lowest daily gain (0.47 and 0.40 kg/day). Calves fed on the 100 % feeding level had an interrmediat value (0.52 and 0.45 kg/day) for Friesian and Buffalo calves respectively.
Male calves had a significantly higher (P < 0.01) daily gain than femal calves in both speices (0.60 vs. 0.46 kg/day for Friesian and 0.51 vs. 0.41 kg/day for Bufalo calves) .
Season of calving had a significant effect (P < 0.01) on daily gain of Friesian calves, in favouring those born in winter season (0.54 vs. 0.52 kg/day). This effect was insiggnificant for Buffalo calves.
The average daily gain for Friesian and Buffalo calves along the experimental period were 0.53 vs. 0.46 kg/day respectively.
1.2. Feed conversion
Feeding level had a significant effect (P < 0.01) on feed conversion. The calves fed on 80 % feeding level showed the best feed conversion efficiency (6.14 vs. 6.29 kg TDN/kg gain) along the experimental period. This efficiency was (7.25 and 7.07 kg TDN/kg gain). for Friesian and Buffalo calves fed on 120 % level. Animals fed on 100 % feeding level had an intermediate value in this respect (6.90 and 6.93 kg TDN/kg gain), for Friesian and Buffalo calves respectively.
Male calves had significantly better (P < 0.01) feed connversion than female calves in both species (5.90 vs. 7.63 and 6.32 vs. 7.21) for male versus females of Friesian and Buffalo calves.
Calves born in winter season showed the better values of feed conversion than those born in summer season in both specieB.
Efficiency of feed conversion was significantly(P < 0.01) decreased in both species as animals getting heavier.
1.3. Feeding and labor costs:
Feeding level had a significant effect (P < 0.01) on the values of feed cost L.E/kg gain, feeding economics and labor cost L.E/head or kg gain. Feed cost/kg gain was increased, while feeding economics and labor cost/head or kg gain were decreased as the feeding level was increased from 80 to 120 % in both species.
The feeding and labor costs(L.E) of one kg gain was 3.07, 3.38 and 3.46 L.E for Friesian calves fed on 80, 100 and 120 % levels of feeding respectively. The corresponding values for Buffalo calves were 3.06, 3.24 and 3.24 L.E respectively.
Season of calving had a significant effect (P < 0.05) on feed cost L.E/kg gain and (P < 0.01) feeding economics in favouring calves born in winter season. While season of calving had insignificant effect on both values of feed cost L.E/kg gain and feeding economics for Buffalo calves.
Feed cost L.E/kg gain was increased, while the feeding economics was decreased as the animals getting heavier.
Buffalo calves had the better values of feed cost L.E/kg gain (2.71 vs. 2.92 L.E/kg gain) and higher feeding economics (1.64 vs. 1.56) than Friesian ones.
II. Blood constituents:
Feeding level had a significant effect on all blood constituents studied. As the feeding level was increased, total protein was decreased (7.45 and 7.38, 6.69 and 6.80 and 6.23 and 6.58 g/100 ml plasma for Friesian and Buffalo calves fed on 80. 100 and 120 % feeding level). Total lipids and cholesterol concentrations were positively correlated with the feeding level in both species.
As live body weight was increased all parameters of blood constituents studied were generally increased in both species.
III. Digestibility trail:
Inclusion of berseem to represet 50 % of the roughage (rice straw) portion improved the digestibility coefficients and the feeding value of the whole ration. The improvement achieved in crude protein digestibility and T.D.N value was 14.92 and 6.25 % respectively.
IV. Slaughtering traits IV.1. Carcass traits:
Feeding level had a significant effect (P < 0.01) on both percentages of empty dressing and visceral fat/F.B.W. As feeding level increased all carcass traits studied were increased in Friesian male calves. This effect was insignifiicant considering the Buffalo male calves. The 100 % feeding level had higher values of carcass weight. fast dressing %, percentages of edible parts and visceral fat/F.B.W, boneless meat% and meat: bone ratio than other two levels(80 and 120~),
Ihile empty dressing % was increased as feeding level was Increased.
Season of calving had insignificant effect on all carcass traits studied except value of empty dressing% in carcasses of mle Friesian calves.
Season of calving of Buffalo calves had a significant effect(P<O.OI) on percentage of edible parts/F.B.W and(P<0.05) fast dressing % in favouring calves born in winter season.
Friesian male calves had higher values of all carcass trai ts studied than Buffalo ones.
IV.2. Fore-and hind quarters traits and eye muscle area:
Eye muscle area was increased significantly as the feeding level was increased in both species. The figures were 99.07, 100.06 and 112.52 cm2 for Friesian male calves and 97.67,101.04 and 107.37 cm~ for Buffalo male calves fed on 80, 100 and 120 % levels of feeding respectively.
Season of calving had insignificant effect on fore-and hind quarters and eye muscle area in Friesian male calves but it had a significant effect on fore-and hind quarters/carcass in Buffalo male calves.
As the slaughter age was increased the hind quarter/ carcass percentage was decreased significnatly (P < 0.05) in Buffalo male calves carcasses.
IV.3. Proximal analysis of the 10 th rib cut :
As feeding level was increased. percentages of both moisture and protein were significantly (P < 0.01) decreased while percentage of fat was increased(P<O.OI) in Friesian male calves carcasses. Regarding Buffalo male calves. percentages of moisture. protein and ash were significantly decreased and the percentage of fat was significantly (P < 0.01) increased as the feeding level was increased.
Season of calving and slaughter age had insignificant effect on proximal analysis of the 10 th rib cut in both species.
Friesian male calves had higher values of fat content (13.07 %) and protein (21.51 %) but lower values of ash(4.84%) and moisture (60.58%) on fresh basis than Buffalo male calves. The corresponding figures were 12.13. 21.27. 5.41 and 61.20 % for fat. protein. ash and moisture in the 10 th rib cut of Buffalo male calves.