الفهرس 
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Abstract
The main objective of this study was to evaluate the effect of supplementation of fibrolytic enzyme (Fibrozyme) during heat stress on the performance of lactating cows and in Sheep.
This study included two experiments in two commercial Farms. The first experiment was conducted in Talaat Mostafa Dairy Farm Company (450 lactating Dairy cow) located in El-Nubaria City, Behera Ggovernorate, Egypt for 5 week, during July and August, 2009. The second experiments were conducted in Eleman Sheep Farm located in EL-Saf, Helwan Governorate, Egypt for 5 weeks during July and August, 2010.
The objective of first experiment was to evaluate the effect of supplementation with Fibrolytic enzyme ”Fibrozyme” during heat stress on the performance of lactating dairy cows. The objective of second experiment was to evaluate the effect of supplementation during heat stress on nutrient digestibility and rumen parameters of Barki lambs.
First experiment
Natural hot summer conditions during the experimental periods were recorded during the day and night using thermohygrometer, where ambient temperature and relative humidity averaged 35 Co and 54 %, respectively which was equivalent to THI of 86-89 during day.
The first study included two groups (with and without Fibrozyme supplementation). The changes in Body temperature, respiration rate, Feed intake, feed conversion, milk production, milk composition, some blood biochemical parameters, thyroid hormone concentrations indices of heat-stressed dairy cows under the previous conditions were determined in all groups.
Ninety two Holstein dairy cows were used in this experiment (G1 = 46. G2 = 46): were G1: received total mixed ration without fibrolytic enzyme and G2: received total mixed ratio with fibrolytic enzyme (Fibrozyme) 15g / h/ d
Second experiment
The second experiment included four groups (Fibrozyme and shaded group, without Fibrozyme shaded group, Fibrozyme and un- shaded groups, without Fibrozyme un-shaded group,). The changes in feed intake, nutrient digestibilities, feeding values, some rumen liquor parameters and feed efficiency indices of heat-stressed sheep under summer conditions were determined in all groups.
Twelve male Barki lambs were used in this experiment (Three ber group): were G1and G3 received in their concentrate portion 10 g of fibrolytic enzyme (Fibrozyme) per head per day
The results are summarized as follows:
First experiment
Under the conditions of this experiment, the obtained results indicated that supplementation of Fibrozyme reduced the average of RR and RT. On the other hand no significant difference was recorded of feed intake as fresh TMR, feed intake as DM, CP, and TDN.
feed conversion as kg DM, CP, TDN, and NEL were significantly improved for cows fed supplemented diet with Fibrozyme (0.835, 0.157, 0.515, and 1.328 kg, respectively in comparing with cows fed without supplementation (1.012, 0.193, 0.624, and 1.609 kg/kg FCM).
Milk yield was significantly increased in cows fed on Fibrozyme compared to those fed control diet (+3.328 kg/d) and that increase was significantly (P<0.05).
There was a significant increase in milk production between all groups in the early, mid and late lactation period.
Milk production increased significantly in supplemented group compared with un-supplemented group in multiparous cows but in primiparous cows the supplemented group increased numerically but not significantly compared with multiparous cows
Milk fat yield, FCM yield, and total solids yield were significantly increased (1.128, 28.67 and 3.67 kg) for cows fed diet supplemented with Fibrozyme compared with (0.865, 23.4, and 3.091 kg/h/day) for cows fed control diet, respectively. While the yield of protein, lactose, and solids not fat were insignificantly increased with Fibrozyme supplementation.
Milk composition was not significantly affected by adding Fibrozyme, except milk fat percentage was significantly increased (3.84) for cows received Fibrozyme compared with un-supplemented cows (3.32 %)
Fibrozyme supplementation caused significant increase in serum total protein content (7.55), glucose (58.55), T3 (, 78.60), total bilirubin (0.22), and Globulin (3.74) compared with 7.20 g/dl, 51.48 mg/dl, 64.88 ng/dl, 0.15 mg/dl and 3.42 g/dl for cows fed without supplement. A/G ration was significant effect for control group compared with supplement group. But contents of albumin, ALT, AST, and urea numerically increased but not significant.
Second experiment
Under the conditions of this experiment, the obtained results indicated that supplementation of Fibrozyme had significant effect on DMI as concentrate, roughage and total DMI (g/h/d) (872.9, 664.0 and 1536.9) vs (918.8,534.6 and 1453.4), Nutrient digestibilities war not significantly affected by adding Fibrozyme as DM,OM, but CP, CF and EE was significant effect for supplemented group (78.06,66.27 and 82.05) compared with control group ( 73.96,55.9 and 75.74)
Feeding values had significant effect by adding Fibrozyme as NFE and TDN (80.46 and 71.89 vs 77.29 and 67.12) but DCP had no significant affect
Using shades affected significantly DMI as a concentrate and roughage (918.8 vs 872.9 and 612.12 vs 586.4) and affecting significantly nutrient digestibilities as DM, OM, CF, EE and NFE ( 78.61,82.11,69.0,79.22 and 70.83 vs 72.69,77.25,53.17,68.56 and 66.62) but CP value was not significant affected. Feeding values as TDN had significant effect (66.86 vs 60.63) but DCP had no significant effect
The Fibrozyme supplement had no significant effect on Rumen liqueur PH value and TVF’S production but shading affected significantly in 3hr. post feeding, Rumen liqueur ammonia concentration in control group was significantly higher than Fibrozyme group and shading group was significantly higher than un-shaded group
It can be concluded that supplementing the diets with Fibrozyme alleviated the heat stress effect in dairy cows through modulating most blood metabolites to its normal range and improving both thyroid activity and feed utilization and enhance milk production, composition of heat-stressed dairy cows under Egyptian summer conditions. It also alleviated the heat stress effect in sheep through improving DMI, nutrient digestibilities and feeding value. It also enhanced some rumen liquor parameters and improved feed efficiency.