42 
Tuberculosis. 
the  two  are  left  together,  especially  indoors,  there  is  a very 
considerable  risk  that  the  calf  will  become  infected  before 
weaning-time.  At  the  same  time,  the  owner  who  finds 
separation  of  the  cows  and  young  calves  impracticable  need 
not  on  that  account  decide  in  advance  that  elimination  is 
impossible  for  him.  It  will  still  be  worth  his  while  to 
maintain  the  separation  between  the  reacting  and  the  non- 
reacting cows,  and  to  face  the  risk  involved  in  allowing  the 
former  to  rear  their  own  calves.  When  the  calves  thus  reared 
come  to  be  weaned,  the  tuberculin  test  properly  carried  out 
can  be  trusted  to  tell  him  which  of  them  have  escaped 
infection,  and  these  only  must  be  drafted  into  the  sound 
division  of  the  herd.  Should  the  plan  of  separating  the 
calves  from  their  mothers  be  adopted,  it  will  still  be  obligatory 
to  have  the  test  applied  to  the  calves  at  weaning  time  before 
concluding  that  they  are  sound. 
The  matter,  of  course,  works  out  more  simply  in  a milking  . 
herd  where  the  usual  custom  is  to  rear  the  calves  by  hand. 
When  the  reacting  and  non-reacting  cows  have  to  be  kept 
on  the  same  farms  (but  in  separate  houses),  a single  calf- 
house  will  serve  for  all  the  calves,  that  is  to  say,  it  is  not 
necessary  to  keep  the  calves  of  the  healthy  and  of  the  diseased 
cows  separate.  But  here  again  the  calf-house  must  be  a 
separate  building,  not  communicating  with  either  cow-house. 
If  sufficient  milk  for  all  the  calves  can  be  obtained  from 
non-reacting  cows  it  may  be  used  in  its  natural  state,  but  milk 
from  the  reacting  cows  should  not  be  used  for  the  calves 
unless  it  has  been  heated. 
The  question  whether  the  reacting  and  the  non-reacting 
animals  should  be  kept  apart  when  at  grass  as  well  as  when 
they  are  indoors  is  obviously  an  important  one,  and  it  demands 
an  answer  whether  the  two  sets  of  animals,  afte*  the  first  test, 
are  kept  at  different  farms  or  in  separate  houses  at  the  same 
steading.  In  the  former  case  the  question  is  raised  as  soon  as 
the  calves  of  the  reacting  cows  have  to  be  sent  to  grass. 
The  answer  to  the  question  must  be  that  when  the  circum- 
stances permit  it  it  will  certainly  be  best  to  keep  the  reacting 
and  non-reacting  animals  apart  in  the  fields  as  well  as  in  the 
houses,  but  again  it  may  be  said  that  if  an  owner  finds  this 
quite  impossible  he  may  still  with  advantage  adopt  all  the 
other  means  of  elimination  that  are  practicable.  The  risk  that 
some  of  the  sound  animals  may  contract  the  disease  at  grass 
will  be  more  than  appreciable,  but  very  much  less  than  when 
diseased  and  healthy  are  kept  under  a common  roof. 
Another  question  that  may  sometimes  have  to  be  con- 
sidered is  whether  a reacting  bull  may  be  used  for  the  healthy 
cows  What  has  already  been  said  in  the  first  part  of  this 
