500 
Journal of Agricultural Research 
Vol. XXIX, No. 10 
The lambing period generally comes in 
the spring, enabling the lamb to get a 
good start before hot weather sets in. 
In the spring there is also an abun¬ 
dance of forage for the suckling ewe. 
The growth of the lamb is retarded by 
high temperature and humidity, by 
excessive rainfall and cold weather. 
The rutting season comes with a fall¬ 
ing temperature and possibly a rather 
wide range between the maximum and 
minimum temperatures. Unfavorable 
conditions at the rutting season or 
during the gestation period tend to 
produce a small fall of lambs, and often 
weak lambs. If these critical periods 
are greatly disturbed, sheep are not 
likely to be numerous or profitable. 
In Illinois, conditions of good sheep 
years are found to resemble the aver¬ 
age conditions prevalent in the best 
sheep countries. The bad years gen¬ 
erally have unfavorable conditions at 
some of the critical periods. The most 
serious condition here is the hot sum¬ 
mer with a high humidity. No prac¬ 
tical methods of overcoming these 
conditions are known. At Urbana, 
Ill., a mean temperature of over 70° F. 
accompanied by a mean relative 
humidity over 80 per cent, retards the 
growth of lambs. A higher tempera¬ 
ture can be tolerated if the humidity is 
lower. 
More attention should be given to 
finding breeds best suited to a locality, 
since the Rambouillets seem to stand 
the unfavorable conditions during the 
summer at Urbana, Ill., better than the 
Southdowns or Shropshires. 
In some sections the limits of suc¬ 
cessful sheep production can be ex¬ 
tended by proper methods of housing. 
The barn maintains a much more uni¬ 
form and higher temperature and hu¬ 
midity than the shed or out of doors. 
But conditions in the barn are not 
entirely satisfactory for the health of 
sheep. 
Sheep thrive best where cool sum¬ 
mers and mild winters prevail and 
where sufficient rainfall is afforded to 
provide good grazing. 
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