تأثير التبريد برش الماء المتبوع بالتهوية على بعض الصفات الفسيولوجية و الإنتاجية في أبقار الفريزيان بعد الولادة تحت ظروف بيئة المناطق الجافة

الملخص EN

The present study was carried out at the Agricultural Research Station (Animal Production Research Farm) located in Hada Al-Sham of the Jamoum Region.

Experimental Procedures 1.

Experimental Animals Thirty lactating purebred Friesian cows of 430-480 Kg.

body weight were clinically normal and free from diseases.

The cows were paired into two similar groups according to their age, parity, body weight, and preview yield.

The first group was exposed to normal managerial conditions and used as a control group, whereas the second group was exposed to cooling as a treatment group.

1.

The first group was kept between 10-00 and 16-00 hr.

under cooling system.

Cows were sprinkled for 30 seconds, followed by forced ventilation for 4.5 minutes.

The cooling cycles were repeated every half an hour.

2.

The second group was kept under normal conditions and served as a control group.

The cows received their daily feeding allowances two times a day in two equal amounts of rations.

Daily allowances were offered in amounts to cover the animal requirements.

Drinking water was available continuously.

The ambient temperature and relative humidity were recorded through the experimental period.

The main results were : a) Physiological reactions ; 1.

Overall means of respiration rate were (56.11–0.12 vs 59.50–0.28 rpm) in the cooling and control groups, respectively.

Difference between the two groups was statistically significant (P < 0.01).

2.

Overall means of pulse rate were (62.75-0.22 vs 70.94–0.25 rpm) for the cooling and control groups respectively.

Difference between the two groups was statistically significant (P < 0.01).

3.

Overall means of rectal temperature was (38.18–0.02 vs 39.25–0.02¡C) for the cooling and control groups, respectively.

Difference between the two groups average was statistically significant (P < 0.01).

4.

Overall means of white skin temperature (WST) and black skin temperature (BST) for the group kept under cooling were lower than those of control group, and the black skin temperature (BST) for the two experimental groups were higher than that of white skin temperature (WST).

b) Hematological and biochemical Parameters: 1.

Averages of RBCs were : (7.50–0.15 X 1012 / L.

vs 6.91–0.12 X 1012 / L.) in the cooling and control groups, respectively.

Difference between the two groups average was statistically significant (P < 0.01).

While averages of WBCs were (7.39–0.15 X 109 / L.

vs 7.05–0.17 X 109 / L.), for the cooling and control groups, respectively.

Difference between the two experimental groups lacked statistical significance.

2.

Mean hematocrit values were: (31.28–0.57 vs 29.66–0.65) for the two groups, respectively.

MCV values were (45.56–0.48 vs 45.43–0.54) 3, Creatine Kinase (CK) (49.90–1.60 vs 52.89–1.82 IU / L), total bilirubin (TBIL) (0.19–3.95 vs 4.22–2.70 mg / dL), liver enzyme AST (60.37–1.24 vs 56.32–1.63 IU / L), total protein (9.32–0.20 vs 8.56–0.23 g / dL), albumin (1.33–0.06 vs 1.45–0.07 g / dL), glucose (27.31–1.38–1.38 vs 67.39–1.75 mg / dL), creatinine (0.08–1.32 vs 1.63–0.09 mg / dL), lactic dehydrogenase (LDH) average (574.82– 12.60 vs 663.20–14.23 IU / L), Alkaline phosphatase (ALP) (7.44–1.12 vs 17.27–1.27 IU / L), Gamma Glutammyl Transferase (GGT) (25.23–0.75 vs 33.22–0.85 IU / L), Uric acid (URCA) (0.65–0.02 vs 0.53–0.03 mg / dL), for the experimental groups respectively.

Differences between averages, generally lacked statistical significance.

The results also showed that calcium (Ca) (0.93–0.22 vs 4.27–0.27 mg / dL) and phosphorus (P) (6.42– 0.15 vs 7.81–0.17 mg / dL) for the two experimental groups, respectively.

Differences between averages were statistically significance.

Total milk yield during different pregnant intervals in the cooling group was higher than that of control group (1951 Kg vs 1095 Kg) in the two groups, respectively.

It was concluded from this study that the adopted cooling system had efficiently ameliorated the depressive effects of sum mer heat stress prevailing in Saudi Arabia on the performance of Friesian cattle.

It seems that the water sprinkling followed by forced ventilation technique is a simple safe and practical method for decreasing the heat stress effects in dairy cows and consequently improve productivity and reproductivity of cows in hot climate.