Hello Salma 

please specify which gene you mean ,

so many quantitative trait genes were cloned successfully.

for example , growth hormone gene which cloned to increase the growth rate of fish and other animals .

regards

Many thanks, Dr/ Hayder

The milk production  trait in cattle controlled by genes located on different chromosomes. So ,can  we enter these  genes in several  vectors ?

 And then, how can we link  between  them to obtain the final product, even if we assume that we deal with proteins produced by each vector.

this is very difficult,  the milk contain so many proteins and it will be very difficult to clone all of their genes . 

an other approach is to clone the main milk protein ( the casien ) and use additives to produce synthetic milk ,

on the other hand it will be easier to clone a gene responsible  for a hormone which control the milk production in cattle , in this case we will produce transgenic animal which can produce high quantity of milk .

best regards .