الفهرس 
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Abstract
The current investigation was carried out at the Animal Production Research Institute (APRI), Dokki, Giza, Egypt’s Mehallet Musa station in the Kafr ElSheikh governorate between October 2021 and December 2021. The aim of the present study was to look at how Egyptian buffalo calves productive performance, certain blood biochemical parameters, antioxidant activity, and rumen development were affected by sodium butyrate (SB) supplementation in both whole milk and starter mixture.
Experimental design:
WM -/SM- The control group was fed whole milk and starter mixture without sodium butyrate supplementation.
WM+/SM- The group received 0.3% sodium butyrate in whole milk only.
WM-/SM+ The group received 0.3% sodium butyrate in the starter mixture only.
WM+/SM+ The group received 0.3% sodium butyrate in both whole milk and starter mixture.
Studied parameters:
1. Body weight was recorded from the start of trial then every 3 weeks till 13 weeks of age.
2. Average daily gain (ADG) and relative growth rate (RGR).
3. Blood biochemical parameters including glucose, total serum protein, urea, beta-hydroxy butyric acid (BHBA), and glucose-1-phosphate dehydrogenase (G1PHD).
4. Antioxidant activity including glutathione peroxidase (GSH-PX), superoxide dismutase (SOD), and malionaldehyde (MDA).
5. Rumen fermentation parameters such as rumen pH, volatile fatty acid concentration (VFA), and ammonia concentration.
6. Ruminal and intestinal morphometry.
The main findings were:
• Body weight differences were found to be non-significant between groups. At the beginning of the trial (day 5 of age), the average body weight was (33) kg, but at the end of the trial, it was increased by (45-47.5) kg across all groups (day 88 of age).
• ADG and RGR were not significantly changed between groups. Control and WM-/SM+ groups expressed higher ADG (P>0.05) (0.60 and 0.59 kg/d, respectively) and RGR (84.4 and 83.9 %, respectively). But the lowest in both parameters was found in the WM+/SM+ group (ADG=0.56 kg/d and RGR=80.6%).
• SB supplementation was significantly increased the blood biochemical markers such as glucose, urea, and G1PHD. While total serum protein and BHBA levels did not differ significantly between groups.
• At day 25 of age, serum glucose levels were (87.9 and 89.5 mg/dl) in WM+/SM- and WM-/SM+ groups, respectively, compared to (51.4 mg/dl, P< 0.05) in the WM+/SM+ group. At other ages, there were no significant differences among all groups. Throughout the whole trial, the WM+/SM+ group recorded the lowest glucose level (65.7 mg/dl), while the highest glucose level was obtained in the WM+/SM- group (78.8 mg/dl).
• There was a significant difference in TP between the WM-/SM+ and control groups on day 25 of age (4.50 g/dl vs. 7.27 g/dl). Furthermore, at day 48 of age, the WM-/SM+ group had significantly lower TP levels than the WM+/SM- and control groups (4.78 g/dl vs. 5.15 and 5.17 g/dl, respectively). Throughout the whole trial, The highest level of non-significant total serum protein was observed in the WM+/SM+ group (5.35) g/dl, while the lowest level was discovered in the WM-/SM+ group (4.77) g/dl.
• Urea levels were significantly higher in the WM-/SM+ group compared to the WM+/SM+ and control groups at day 25 of age (48.3 mg/dl vs. 32.3 and 38.6 mg/dl, respectively). The WM-/SM+ group had the highest overall mean of blood urea throughout the trial, which differed significantly from the WM+/SM+ group (51.9 mg/dl vs. 44.6 mg/dl, P< 0.05).
• At day 66 of age, BHBA level increased significantly in the control group compared to the WM+/SM- group (0.43 mmol/L vs. 0.36 mmol/L).
• All SB-supplemented groups had significantly higher levels of G1PHD than the control group at day 25 of age. Additionally, the highest overall mean of G1PHD was expressed in the WM-/SM+ and WM+/SM+ groups (39.9 mM). In contrast, the control group showed a lower level of G1PHD (36.6 mM).
• GSH-PX and MDA revealed non-significant differences between groups. The WM+/SM+ group had a higher non-significant amount of GSH-PX (366 mu/ml). While a higher non-significant MDA level was observed in the WM-/SM+ group (6.03 nmol/ml). On the other hand, there were significant differences between groups in SOD levels. The WM-/SM+ group exhibited the greatest amount (95.3) u/ml, and the control group exhibiting the lowest level (79.0) u/ml. SOD levels were higher in the WM-/SM+ group at day 25 of age (103 u/ml) versus (77.9 u/ml) in the control group. Additionally, on day 66 of age, the non-supplemented group had the lowest level (79.7 u/ml) compared to (102) u/ml in the WM-/SM+ and WM+/SM+ groups.
• Rumen pH differed significantly between groups at all time intervals. The rumen pH of calves that received SB in both whole milk and the starter mixture was low at all time intervals and throughout the experiment, while the highest levels were recorded in the WM+/SM- group except at day 48 of age, a higher pH level was recorded in the WM-/SM+ group. Throughout the whole trial, the WM+/SM- group had the highest overall rumen pH level (6.90), followed by the WM-/SM+ group (6.87), while the WM+/SM+ group had the lowest overall level (6.43).
• The WM+/SM- group showed higher non-significant levels of total VFA concentration and propionate (161 and 21.9 µm /L, respectively), but the lowest levels of total VFA and propionate were found in the control group (153 µm /L and 20.2 µm /L, respectively).
• Acetate was significantly decreased with SB supplementation. At day 48 and 66 of age, the control group was significantly higher than the WM+/SM+ group. Throughout the whole trial, the lowest levels of acetate was detected in the WM+/SM+ group (57.9) µm /L). On the other hand, the greater level of acetate was seen in the control group (61.2 µm /L).
• Butyrate was significantly increased with SB supplementation at day 25 of age and decreased at day 66 of life. The WM-/SM+ and WM+/SM+ groups had the greatest butyrate levels at day 25 of age (11.6) µm /L. While, at day 66 of life, the control group had a higher level (12.9) µm /L. On the other hand, the WM-/SM+ and WM+/SM+ groups had higher non-significant levels of isobutyrate (1.92) µm /L than the control group (1.78 µm /L).
• Valerate and isovalerate levels increased significantly by SB supplementation. Valerate and isovalerate were measured at higher significant levels in WM+/SM+ calves (3.27 and 2.25 µm /L, respectively), but the lowest levels were observed in the control group (2.83 and 1.51 µm /L, respectively). On the other hand, introducing SB to calves feed significantly reduced the acetate-to-propionate ratio (A-P ratio), where the lowest value was recorded in the WM+/SM+ group (2.70).
• Ammonia concentration in rumen fluid was not significantly affected by SB supplementation. The WM+/SM- group had the highest level of ammonia concentration (7.04 mg %), while the control group had a lower level (5.44 mg %). At day 25 of age, calves that received SB in WM only had a higher level of ammonia (7.48 mg%) compared to (4.35 and 4.50 mg%) in the WM-/SM+ and WM+/SM+ groups, respectively (P = 0.001). Furthermore, at the end of the trial, ammonia concentrations varied significantly between groups. The WM+/SM- calves had the highest levels of ammonia (7.13 mg%) compared to the control group (5.57 mg%) (P = 0.015).
• In comparing the SB-supplemented group with the control group, the rumen papillae (RP) length was (211 µm vs. 625 µm), width (188 µm vs. 194 µm), tunica muscularis (TM) thickness of the rumen (923 µm vs. 1169 µm), crypt depth of the small intestine (166 µm vs. 207 µm), and mucosal thickness of the large intestine (357 µm vs. 533 µm) for the SB-supplemented groups and control group, respectively. While the villous height did not differ significantly.
In conclusion, it is safe and enhances rumen growth and fermentation to add 0.3% of SB to WM, SM, or both. SB supplementation had little effect on body weight, but it had no significant influence on ADG and RGR, suggesting that the calves growth performance had not improved. Glucose, urea, and G1PHD levels were changed significantly with SB supplementation, while BHBA and total serum protein did not differ. This refers to faster tissue growth because glucose is a precursor to tissue growth. In addition, SB supplementation had a significant effect on the immune status of calves as was evidenced by significantly higher levels of SOD and the non-significant increase in GSH-PX and decrease in MDA levels.
A significant increase in rumen pH and the non-significant increase in total VFAs and ammonia content all contributed to an improvement in rumen fermentation. Also, the RP length and width, TM thickness of the rumen, crypt depth of the small intestine, and large intestine mucosal thickness were primarily enhanced in the SB supplemented groups compared to the control group. This indicates that SB supplementation had a powerful effect on rumen development.