Dairy Sheep Symposium - the Department of Animal Sciences ...

In 1999, 119 ewes ended their lactations between February 1 st and June 1 st . Individual ewes in
that group had lactated for as few as 75 days up to as many as 391 days. As they were taken from
the parlor, they were added to the breeding group that included the light control ewes from
January of that year. Of these ewes, 82 percent were marked, and 60 percent lambed that Fall,
indicating that the 20-hour day length worked for out of season breeding, even when the ewes
were lactating while exposed to extended day lengths.
In 2000, 155 ewes ended their lactations between February 1 st and June 1 st , and were folded
into the appropriate light control breeding groups. Of those 155 ewes, 67 percent lambed that
Fall.
In 1997, before starting the light treatment protocol, thirty percent of ewes that ended their
lactations between those dates lambed in the Fall and in 1998 only six percent of ewes with
lactations ended between February 1 st and June 1 st lambed in the Fall.
Percentage
100
80
60
40
20
0
Ewes that left parlor in Spring and lambed in Fall
20
6
60
1997 1998 1999 2000
Year
67
Natural
Light Treatment
For the 2000 Fall lambing season we started 225 ewes in the light treatment protocol, in five
different groups. Forty production ewes started the 20-hour days on December 15 th in 1999; 43
production ewes and 45 elite ewes (mostly replacements) were started in separate groups on
January 15 th 2000; and 24 elite ewes (also mostly replacements) and 73 production ewes, in
separate groups, were started on February 15 th , 2000. Each of these groups was taken out of the
light control barn as their 60-day periods were completed.
The results were as follows:
• The 12/15/1999 Production Group: 69 percent of the 40 ewes lambed in the fall of 2000
• The 1/15/2000 Production Group: 55 percent of the 43 ewes lambed in the fall of 2000.
• The 1/15/2000 Elite Group: 8 percent of the 45 ewes lambed in the fall of 2000.