Effect of recombinant bovine somatotropin (RBST) administration on mammary gland function during pregnancy in Friesian cows

تأثير الحقن بهرمون النمو المخلق على نشاط الغدة اللبنية التخليقى اثناء الحمل في ابقار الفريزيان
Abstract: Ten multiparous pregnant lactating Friesian cows (2-3 months in pregnancy) were used in this study. Cows were between the 2nd and 5th parities and their live body weight was between 450-520kg at the beginning of the experiment. Experimental cows were divided into two equal symmetric groups; five as a control group receiving sterilized physiological saline (0.9%NaCl), and the other five cows were injected with 500mg long acting Recombinant Bovine Somatotropin (rbST, Somatech®, Elanco, Indianapolis, IN, USA) at injection intervals of 14 day.
Milk yield was recorded for each cow individually to compare milk productivity changes due to the experiment. Milk samples (50ml.) were divided into two equal halves (25ml each) were taken once a week as a composite sample for whole day milking (animals milked twice daily). Milk constituents (fat, total protein, lactose, total solids, and solids not-fat) as well as somatic cell count were determined immediately using Milkoscan® analyzer and Somatic®, respectively using the first half of milk samples. The other half was saved by adding potassium Dichromate as a preservative for sodium ion analysis.
Blood samples (10ml) were taken biweekly from the Jugular vein in a heparinized tube. Heparinized blood samples were divided into two parts; the first one was used for determination of hemoglobin concentration and hematocrit values. The other part of blood was centrifuged at 3000r.p.m for 20 minutes to separate blood plasma, which was stored at –20°C until hormonal (IGF-I) assay.
Mammary tissue biopsies were taken form the back left quarters from every cow surgically for histological examination. Histological measurements were done by using a computer image analysis using AutoCAD® program.
Hemoglobin and hematocrit were significantly decreased in rbST-treated cows. Plasma total protein, total lipids, and Creatinine were not significantly affected by rbST treatment. When plasma Urea, AST and ALT were significantly higher in rbST-treated cows than control cows.
Concentrations of plasma Insulin like growth factor-I were significantly increased by rbST treatment by 45.32%.
Actual milk yield and Adjusted milk yield for 305days in lactation were not significantly affected by rbST treatment. However, daily milk production and daily fat-corrected milk production significantly elevated by recombinant bST treatment.
There were not significant effect of rbST on milk Solids not fat, Lactose, total protein, ash percent, and sodium ion concentration.
Recombinant bST significantly decreased milk fat percent but not milk fat content and proportion of milk sodium ion to milk ash. However Somatic cell count (SCCX103) was decreased in saline-treated cows than rbST-treated group.
Mammary gland histological examination revealed that, the parenchymal tissue was significantly higher due to rbST treatment than controls by 38.01% when stroma percent was significantly decreased due to rbST treatment.
Generally recombinant bovine somatotropin exerts both lactogenic and mammogenic effects on the mammary gland of pregnant Friesian dairy cows in late lactation period.
Publication year 2005
Pages pp. 95
Availability location مكتبة معهد بحوث الانتاج الحيوانى-شارع نادى الصيد- الدقى - الجيزة
Availability number 921
Organization Name
Country Egypt
Author(s) from ARC
Agris Categories Animal physiology - Reproduction
AGROVOC
TERMS		 Cows. Fats. Lactose. Mammary glands. Milk yield. Pregnancy. Somatic cell count. Somatotropin.
Proposed Agrovoc Milk constituents;total solids;potassium Dichromate;
Publication Type Master Thesis
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