加拿大科学家研究了新的奶牛性别控制方法

生物谷

    　加拿大安大略省圭尔夫大学的博士Peter  Blecher以及他的父亲一起在研制如何选择奶牛的性别，这项研究似乎可以允许农民们使用人工受精的方式来选择他们需要的奶牛或者是猪的性别。这将会对整个农业造成极大的冲击。

　　但是Peter  Blecher博士称，没有一个发疯的科学家会使用基因技术来控制一种物种，我们只是消除精子中我们不需要的性别，我们并没有对基因物质进行变动，最终用来受精的精子根本没有被接触。这个已经申请了专利的技术就是使用一种可以聚集所有性别特定蛋白的抗体除去不需要的性别。这样可以提高奶农们对奶牛性别的选择性。

Sex  in  the  barnyard  may  never  be  the  same.

A  new  process  that  appears  to  allow  farmers  to  choose  the  sex  of  their  cows  and  pigs  in  artificial  insemination  has  the  potential  to  revolutionize  commercial  agriculture.

But  these  aren't  mad  scientists  using  genetic  technology  to  manipulate  a  species,  stresses  Dr.  Peter  Blecher,  whose  father  Stan  developed  the  process  at  the  University  of  Guelph.

"We're  just  removing  the  sperm  of  the  sex  we  don't  want,"  said  Blecher,  founder  of  Sequent  Biotechnologies,  whose  sperm-sexing  technology  inspired  a  recent  friendly  takeover  by  Microbix  Biosystems  Inc.  (TSX:BMX).http://www.microbix.com/

"There's  no  manipulation  of  genetic  material  at  all.  The  sperm  that's  used  in  the  ultimate  fertilization  is  untouched  in  any  way."

The  patented  technology  uses  an  antibody  that  can  clump  together  all  the  sex-specific  proteins  in  a  semen  sample  and  remove  whatever  sex  is  not  wanted.  That  can  mean  major  opportunities  for  producers  who  have  only  a  50  per  cent  chance  of  getting  the  sex  of  animal  they  want  through  artificial  insemination.

The  desire  to  pre-determine  sex  has  been  an  issue  for  centuries.

"Since  King  Henry  VIII  started  chopping  the  heads  off  his  wives  it's  been  something  that's  been  a  riddle  to  scientists,"  said  Blecher.  The  British  monarch  executed  two  of  his  six  wives,  blaming  them  for  not  being  able  to  produce  male  heirs.

But  while  baby  determination  is  an  ethical  minefield  among  humans,  it  represents  billions  in  increased  efficiency  to  livestock  producers  around  the  world.  For  example,  dairy  farmers  obviously  prefer  offspring  to  be  milk-producing  females.

Beef  producers  prefer  male  calves,  which  convert  feed  into  lean  muscle  mass  far  faster  than  females.  That  can  have  huge  implications  to  cattle  ranchers  who  operated  on  razor-thin  margins  even  before  the  mad  cow  crisis  ravaged  the  industry.  Female  pigs  are  easier  to  control.

"Look  at  any  major  global  business  that's  operating  on  a  50  per  cent  inefficiency,"  said  Blecher.  "That  would  be  considered  disastrous  by  any  standards."

Dairy  operator  Michael  Hall  says  the  technology,  if  proven,  would  be  a  natural  evolution  of  the  artificial  insemination  industry.

"If  I  could  pick  the  top  25  per  cent  of  cows  in  my  barn  and  make  sure  they  have  heifers  every  year,  that  would  be  a  significant  production  advantage,"  said  Hall,  a  director  with  the  Dairy  Farmers  of  Canada,  who  runs  an  operation  south  of  Ottawa.

Semen  sexing  has  been  available  in  the  United  States  and  Europe  for  several  years,  but  there  has  been  limited  uptake  across  the  industry  because  it  is  expensive  and  invasive,  says  reproduction  physiologist  Michael  Dyck.

"Artificial  insemination  has  revolutionized  the  dairy  industry,"  said  Dyck,  who  teaches  animal  science  at  the  University  of  Alberta  and  focused  research  on  embryonic  transfers  in  swine.

"This  could  be  a  very  nice  add-on  to  that."

Further  testing  and  field  trials  of  the  technology  will  be  done  over  the  next  three  years  by  Microbix,  which  specializes  in  the  development  of  biotherapeutic  drugs,  vaccines,  and  infectious  disease  diagnostics.  The  company  expects  a  market  launch  in  2008.

Dyck  doubts  there  will  be  many  ethical  concerns  raised.

"This  technology  has  been  developed  in  parallel  with  things  like  cloning  or  trans-genesis,"  he  said.  "So  when  you  put  this  alongside  that  kind  of  manipulation,  the  animal  rights  activists  are  probably  going  to  lean  more  toward  (protesting)  genetic  manipulation."

And  while  producers  across  Canada  have  embraced  artificial  insemination,  many  cattle  are  still  reproducing  the  old  fashioned  way  as  Nature  intended.

"There's  still  a  large  percentage  of  herds  that  .  .  .  still  use  a  barnyard  bull,"  said  Hall.