EFFECT OF ONCE-DAILY MILKING AND CONCURRENT SOMATOTROPIN ON MAMMARY TIGHT JUNCTION PERMEABILITY AND YIELD OF COWS

Citation
K. Stelwagen et al., EFFECT OF ONCE-DAILY MILKING AND CONCURRENT SOMATOTROPIN ON MAMMARY TIGHT JUNCTION PERMEABILITY AND YIELD OF COWS, Journal of dairy science, 77(10), 1994, pp. 2994-3001
Citations number
19
Categorie Soggetti
Agriculture Dairy & AnumalScience","Food Science & Tenology
Journal title
ISSN journal
00220302
Volume
77
Issue
10
Year of publication
1994
Pages
2994 - 3001
Database
ISI
SICI code
0022-0302(1994)77:10<2994:EOOMAC>2.0.ZU;2-0
Abstract
Six pairs of monozygous Friesian twin cows during late lactation were used to assess the effect of once daily milking and bST treatment on y ields and tight junction permeability of mammary epithelial cells. Dur ing the first 7 d, all cows were milked twice daily; on d 8 through d 21, all cows were milked once daily, but one cow of each twin pair was treated daily with 20 mg of bST on d 13 through 21; and, finally, dur ing d 22 through 28, all cows were again milked twice daily. Once dail y milking, a common management practice in New Zealand, resulted in a small (7%) but significant decrease in milk yield. Treatment with bST increased milk yield by 19%, thereby exceeding the milk yield loss fro m once daily milking. The integrity of mammary tight junctions was ass essed indirectly by measuring concentrations of plasma lactose and mil k BSA. Once daily milking temporarily disrupted tight junction integri ty, based on 4- to 5-fold increase in plasma lactose and a 42 to 55% i ncrease in the concentrations of milk BSA. In the present study, bST d id not affect the permeability of mammary tight junctions.