الفهرس 
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Abstract
A Syndrome of weak calves has a drastic economic impact on livestock production as it affects animal’s rate of body weight gain, marketing, day to the first calving, herd survivorship and future productivity(Radostits, et al.,1994; Underwood and Suttle, 1999). Ill thriftiness in calves is a symptom that can be caused by a large number of factors including genetics, management issues, poor quality colostrum, housing, improper adequate nutrition, trace element/vitamin deficiencies or infection. Oxidative stress may also be a cofactor in the development of such condition leading to serious systemic effects and impairing its vitality (Gitto et al., 2009; Guzelbektes et al., 2012 and Mutinati et al., 2013). Therefore, the present study aimed to determine the percentage of weak calves and possible causes related to calf weakness in our local area, investigate the status of glucose and total protein , oxidant biomarker (MDA) and enzymatic antioxidants in weak calves and their potential role in the healthy status of these animals, assessing trace elements (Zn, Cu, Fe ) which play an important role in enzymatic antioxidant.
A total number of 86 cow calves of both sex (1weeks -6 months) reared at small holder farms at some areas (Sohag governorate) were subjected to study, Assessing weak calf was carried out according to methods descried by Radostits et al., (2007), Ahmed and Nabil (2007), and Aref, et al., (2016).
Weak calf syndromedivided into 2 main groups according to clinical examination 1st group control including 28 healthy animal ,second diseased group including 58 diseased animal suffered from stunting or delayed growth which divided into 4 groups including 1. Ill-thriftiness(26), ill-thrift calf with Diarrhea(13), weak calf with respiratory distress(11) and Vesicular Stomatitis (suspect FMD) (8).
Weak calf syndrome showed signs of ill-thriftiness (67%) in 58 diseased animal in the form of stunting or delayed growth with alopecia, rough hair, poor body condition, emaciation, hypo motile rumen deprived appetite (eating mud, stones, plastic object) and pale mucous membrane.
Obtained results of biochemical analysis revealed highly significant reduction (P<0.001) reduction in the mean value (±SD) of the blood serum concentration of copper (67.91±13.64µg/dl), total iron (174.02±31.94µg/dl), zinc (72.24±13.47µg/dl), glucose (3.61±1.060mmol/L) and total protein (53.035±7.87g/L). There were highly significant reduction (P<0.001) in the activity of enzymatic antioxidants (CAT, SOD, GPx) associated with highly significant(P<0.001) increase in oxidative biomarker. The mean values (±SD) of CAT, SOD, GPx and MDA were 422.26±86.24U/L, 268.49±30.29U/ml, 48.82±6.29U/ml, 5.19±1.25nmol/ml, respectively.Ill thrift calves with diarrhea had highly significant reduction (P<0.001) in the blood level of Zn (80.19±10.86µg/dl),Cu (86.15±6.81µg/dl) and Fe (183.48±23.84µg/dl)compared to the control group while there were significant decreased (P<0.05) inblood glucose level (3.50±0.386mmol /L) and total protein (73.51±13.01 g/L) compared with control group.Data also revealed marked increase of the blood level of MDA (5.38±1.32nmol/l) and marked decreases ofCAT(409.57±60.62U/L), SOD (272.1±29.02U/ml) andGSHpx(44.81±6.22U/ml) in these animals compare to control ones. Weak calves with respiratory distresshad highly significant(P<0.001)increasein blood level of MDA (4.99±1.1nmol/ml). Furthermore, antioxidant systems enzymes were notablydepressed compered to control group. The Mean values (±SD) of SOD, CAT and GPx were 286.82±18.33U/ml, 470.78±69.05U/L and 48.82±6.29U/ml, respectively. Blood Zn and Fe were Highly significant decreased (100.78±17.85µg/dl) Fe (210.36±11.46µg/dl) while there was non-significant variation the blood Cu level(113.31±16.68µg/dl). There was highly significant decreased in the blood of glucose level (3.33±0.813mmol /L)there was non-significant variation in total protein(58.42±8.94g/L) compared to control groups.Serum analysis of oxidative and antioxidant parameters in weak calves suffered from vesicular stomatitis (suspect FMD) revealed a high significant increase in serum level of MDA (8.37±0.77nmol/ml) and significant reduction in enzymatic antioxidant levels:SOD (238.43±28.77U/ml) , CAT (265.03±24.1U/L)andGSH Px (38.63±6.68U/ml). There was marked reductionin the serum level of total protein (50.95±4.64 g/L),zinc(89.18±8.73 µg/dl)andtotal iron (169.78±21 µg/dl). However, there wasmarked increase in the blood glucose and copper levels, (5.15±0.591mmol /L and 134.53±16.52 µg/dl, respectively).
In conclusion, early weaning, improper nutrition and management, diseases (parasitic infestation, diarrhea, respiratory discress and vesicular stomatites FMD) and others factors are possible risk factors related to WCS in small householders.Marked increase of MDA with depressed antioxidant systems (SOD, CAT and GPx enzymes) were notably in WCS that strongly suggeted oxidative stress observed in weak calf syndrome (WCS).Hypocuprosis, hypozincemia, and hypoferremia were reported in WCS in the present study and could be due to illthrift, infection and stress increase an animal’s mineral needs and tends to exacerbate existing mineral deficiencies.Total protein levels were affected by health and nutrition as total protein level decrease in case of ill thriftiness, , diarrhea, respiratory and vesicular stomatites (FMD).Energy levels were affected by health, and nutrition as glucose level decrease in WCS due to ill thriftiness, but surprisingly increase in vesicular stomatites suspect (FMD). from the aformentioned, we could recommend that avoiding or minimizing risk factors of weak calves syndrome during earlystage of life is essential to promote normal growth and improve vitality and health condition of calves. The periodic assessments of oxidative status in ruminants is necessary and could be used as early biomarkers for evaluating health condition of calves. Antioxidant and immune stimulant drugs are highly recommended during treatment of diseased calves to enhance their body defense system.