Quantitative PCR amplifications were done with a final primer concentration of 0.5 mM. Primer design was done using the Primer Select program of the DNA Star software suite. The sequences, annealing temperatures and amplicon sizes of the oligonucleotides used in this study are provided in Table 1 . The PCR products obtained by quantitative PCR were evaluated by melting point analysis and agarose gel electrophoresis. Amplifications were done at 40 cycles of 15 sec. at 95uC, 15 sec. at the indicated annealing temperature and 30 sec. at 72uC. Data were collected at the end of each PCR cycle. Standard curves for all genes were generated from serial dilutions of a plasmid containing the cDNA for each gene. The crossing points obtained from the sample analysis was then correlated with the standard curves to provide a concentration of the individual PCR product. Expression of the casein genes was then correlated with expression of the reference genes (b-actin or GAPDH) in the same sample (expressed as pg of gene per pg of reference).