Abstract
The aim of this study was to examine the correlation between bovine casein (CN) mRNA expression levels in mammary epithelial cells and lactation period, the yields of milk proteins and other parameters. The cells were collected from each cow's milk, which contained somatic cell counts (SCC) of less than 100,000 cells/ml. The levels of αs1-, αs2-, β- and κ-CN mRNA expression were significantly correlated with each other in mammary epithelial cells (p<0.01). All cows produced either less than 30 kg/day/cow or a over 30 kg/day/cow level of milk yield (MY). It was shown that the CN mRNA expression levels decreased gradually from the calving period to late lactation, when MY was over 30 kg/day/cow. The SCC tended to increase gradually during the course of lactation, but it was negatively correlated with milk protein and CN yields (p<0.01) when MY was less than 30 kg/day/cow. Moreover, there was a tendency for a negative correlation between SCC and αs1-CN and β-CN mRNA expression level, when MY was less than 30 kg/day/cow (p<0.05). (Key Words : Casein mRNA Expression, Mammary Epithelial Cells, Lactation Period, Milk Yield, Casein Yield, SCC)
Highlights
IntroductionBovine casein micelle are made up of αs1-, αs2-, βand κ-casein (CN), while genetic polymorphisms have been found (Grosclaude et al, 1979)
Caseins are the major protein components in bovine milk
The aim of this study was to investigate whether the bovine CN mRNA expression levels in mammary epithelial cells collected from raw milk, in which the somatic cell counts (SCC) level was below 100,000 cells/ml, changed during the course of lactation and whether this increase or decrease was correlated with milk yield and other parameters
Summary
Bovine casein micelle are made up of αs1-, αs2-, βand κ-casein (CN), while genetic polymorphisms have been found (Grosclaude et al, 1979). The casein genes exist on chromosome 6 in the order αs1-CN, β-CN, αs2-CN, and κ-CN within the 200-kb casein locus cluster (Mercier and Vilotte, 1993). The mouse casein micelles consist of α-, β-, γ- and κ-CN, and these genes have a high sequence similarity with those of bovine αs1-, β-, αs2- and κ-CN respectively (Mercier and Vilotte, 1993; Kuraishi et al., 2000). In mouse β- and γ-CN mRNA, the length of the poly-(A) tail was decreased by weaning during 24 h after parturition, whereas the poly-(A) tail length for both CN mRNAs was increased after nursing during 12 h (Kuraishi et al, 2000). Travers et al (1996) reported that the level of Obihiro University of Agriculture and Veterinary Medicine, Obihiro-shi 080-8555, Japan
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
