| Abstract |
Dietary protein sources, season of calving, number and stage of lactation were suggested to be seasonal, nutritional and managerial factors that have a significant effect in these aspects. Plasma total protein and its fractions, total lipids, cholesterol, GOT and GPT were estimated as the most metabolic parameters that are closely related to milk yield and composition.
A number of 24 crossbred (Friesian X Balady) cows were used in this study. Dietary protein was applied from Black seed meal (BCM), Roquette seed meal (RCM), undecorticated sunflower meal (SFM)and undecorticated cotton seed meal (CSM) in the ration of animals of 1 st , 2 nd, 3 rd , and 4 th groups respectively. Each protein source was substituted with 50% of the ration's protein ingredient.
I - Effect of dietary protein sources on:
A: Milk field and its Constituents:
Dietary protein sources had highly significant effect (P<0.00l) on average actual daily milk yield (MY), 4% fat corrected milk yield (FCM), fat yield (FY) and percentage (F%), protein yield (PY), and total solids yield (TSY) and percentage (TS%), solids-not-fat yield (SNFY) and percentage (SNF%), lactose yield (LY) and percentage (L%) and ash% (P<0.0l). On the other hand, protein percentage (P%) and milk PH value were not affected by dietary protein source. The higher average of MY (9.09 kg/cow/day), FCM (8.23 kg/cow/day) and yields of FY (305.8 g/cow/day), PY (288.2 g/cow/day), TSY (1091.97 g/cow/day), SNFY (786.1 g/cow/day) and LY (433.98 g/cow/day} was observed in cows fed ration containing black seed meal. However the milk from cows fed ration containing cotton seed meal had the highest average of F% (3.7), TS, SNF% (8.72 ), L% (4.78) and ash% (0.717).
B: Blood plasma constituents:
Dietary protein source had highly significant effect (P<0.00l) on blood plasma total proteins (TP), albumin (AL), globulin (GL), total lipids (TL) and total cholesterol (TC). On the other hand, plasma GOT and GPT showed no significant variation due to dietary protein source. Cows fed ration containing CSM had the highest average of plasma TP and GL (11.16 and 5.16 g/100ml, respectively). While, the highest average of plasma AL (6.53 g/100ml), TL (410.8 mg/l00ml) and GOT (41.88 V/I) was observed in cows fed ration containing RCM. The highest value of TC (211.2 mg/100ml) was observed in cows fed ration containing SFM.
II - Effect of season of calving on:
A: Milk vied and its Constituents:
Season of calving had highly significant effect (P<0.00l) on MY, FCM, PY, TS% and TSY, SNF% and SNFY, L% and LY, and ash%. Significant variation (P<0.05) was also found in FY and P%. On the other hand, milk F% and PH value were not significantly affected by season of calving. The highest average of MY(8.82 kg/cow/day), FCM (7.97 kg/cow/day) and FY, PY, TSY, SNFY (295.7, 274.1, 1050.0 and 754.5 g/cow/day, respectively) and ash % (0.738%) were observed in cows calved during spring months. However, cows calved during summer months had the highest average of P% (3.3), TS% (12.41), SNF% (8.87) and L% (4.85) and LY (419.4 g/cow/day) and PH value of milk (6.62).
B: Rectal temperature and body weight:
Highly significant variation (P<0.001) in rectal temperature and body weight of the cows were observed due to season of calving. The highest average (39.18 C) of rectal temperature was observed in cows calved during winter season. However, the lowest average (38.78 C) was observed in cows calved during autumn. On the other hand, the highest average (452.1 kg) of body weight was found in cows calved during spring. While the lowest average (413.9 kg) was observed in cows calved during winter.
B: Blood plasma constituents:
Season of calving had highly significant effect (P<0.00 1) on blood plasma TP, GL, TL and TC and (P<0.0I) on plasma AL,. On the other hand, season of calving did not affect plasma GOT and GPT levels. Cows calved during autumn months had the higher average of plasma albumin (6.46 g/100ml), total lipids (419.3 mg/l00ml), TC (232.4 mg/l00ml) and GPT (20.08 U/I) level. While, the highest average of plasma TP(11.06 g/100ml) and GOT (39.99 U/I) was observed in cows calved during summer season. On the other hand, the highest value of plasma GL (4.98 g/100ml) was found in cows calved during winter one.
III - Effect of lactation number on:
A: Milk vied and its Constituents:
Lactation number was found to have high significant effect (P<0.00 1) on average of MY, FCM, FY, PY, TS, SNFY and LY and percentages. Significant variations (P<0.01 and P<0.05) due to lactation number were observed in fat and protein percentage, respectively. On the other hand, ash percentage and milk PH value were not affected by number of lactation. The highest average of MY (9.80 kg/cow/day), F% (3.64%) and FY (346.2 g/cow/day), FCM (9.11 kg/cow/day) and yields of PY, TSM, SNFY and LY (305.3, 1164.0, 817.7 and 445.9 g/cow/day, respectively) was observed in cows having 4 lactations. However, the highest values of TS%, SNF% and L% (12.18, 8.74 and 4.84%, respectively) were found in cows having 1lactation. On the other hand, the highest mean of protein percentage (3.35%) was observed in cows having 2 lactation. However, the higher average of ash percentage (0.711 %) and milk PH value (6.58) was noticed in cows having 3 lactations.
B: Blood plasma constituents:
Lactation number had highly significant effect (P<0.00 1) on blood plasma total proteins, albumin, globulin, total lipids and total cholesterol. On the other hand, lactation number did not affect plasma GOT and GPT. The higher averages of plasma total proteins (11.59 g/100ml), albumin (6.79 g/l00ml), total lipids (475.4 mg/100ml), and GOT (40.47 V/I) were found in cows having 2 lactation. While, the highest average of plasma globulin (4.96 g/100ml) was observed in cows having 3 lactation. The highest total cholesterol level (218.0 mg/l00ml) was observed in cows having 4 lactations and higher plasma GPT level (20.34 V/I) was recorded in cows having 5 lactations.
IV - Effect of stage of lactation on:
A: Milk vied and its Constituents :
Stage of lactation had highly significant effect (P<0.00 1) on average of MY, FCM, milk F%, P%, TS%, SNF% and L% and LY and ash%. On the other hand, milk PH value was not affected by stage of lactation. The highest averages of MY, FCM (12.32 and 10.93 kg/cow/day, respectively) and FY, PY, TSY, SNFY and LY(400.4, 406.1, 1481.0, 1081.3 and 584.4 g/cow/day, respectively) were observed at the first week of lactation period. On the other hand, the highest values of F%, TS%, and SNF% (4.16, 13.11 and 9.00%, respectively) and milk PH value (6.56) were found at the end of lactation period.
B: Blood plasma constituents:
The stage of lactation had insignificant effect on all blood plasma constituents studied except plasma TC which was significantly affected (P<0.05) by this factor. The highest averages of plasma TP and AL (11.11 and 6.98 g/100ml), respectively) were estimated at the end of lactation period. While, the highest averages of plasma GL (5.07 g/100ml), total cholesterol (219.1 mg/100ml), total lipids (426.5 mg/100ml), GOT (44.33 VII) and GPT (20.98 V/I) were observed at the 13th, 17th, 33 th, 37th and 33 th week of lactation period, respectively.
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