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

two-year-olds in 2001. East Friesian-sired F1 ewes (1/2EF) were mated to either East Friesian or
Lacaune rams to produce both 3/4EF and 1/2LA1/4EF lambs. Likewise, Lacaune-sired F1 ewes
(1/2LA) were mated to either Lacaune or East Friesian rams to produce 3/4LA and 1/2EF1/4LA
lambs. Lambs were raised on their dams or on milk replacer until 30 days of age. After weaning
at 30 days of age, lambs were raised on high-concentrate diets in confinement. Male lambs and a
few cull female lambs were marketed, and the majority of ewe lambs were retained as replacements.
The ewe lambs of 3/4 dairy breeding born in 2000 (n = 65) were also exposed to either East
Friesian or Lacaune rams in the autumn of 2001 and produced lambs of 7/8 dairy breeding in the
spring of 2001 of the following breeding: 7/8EF, 3/4EF1/8LA, 5/8EF1/4LA, 1/2EF3/8LA, 1/
2LA3/8EF, 5/8LA1/4EF, 3/4LA1/8EF, 7/8LA. Lambs were weaned from their dams at 30 days
of age. After weaning, lambs were raised on high-concentrate diets in confinement. Male lambs
and a few cull female lambs were marketed, and the majority of ewe lambs were retained as
replacements.
In future years, each breed group of ewe will continue to be mated to both East Friesian and
Lacaune rams. This mating plan will result in ewes that are of very high percentage dairy breeding
with breed groups representing a continuum from high percentage East Friesian and no
Lacaune breeding to various combinations of East Friesian and Lacaune breeding to high percentage
Lacaune and no East Friesian breeding. Some of the breed groups are now represented
in very small numbers, but these will increase as the study progresses.
Dairy ewe lambs were placed on our DY30 milking system for their first lactation at approximately
one year of age. The DY30 system is as follows: ewes nurse their lambs for approximately
30 days, after which lambs are weaned onto dry diets, and ewes are milked twice per day
until a test day on which their total daily milk yield is less than .5 lb. Second lactation dairy
ewes were placed on either the DY1 or MIX milking system. The DY1 system is as follows:
lambs are weaned from ewes within 24 hours of birth and raised on milk replacer until weaned
onto dry diets at approximately 30 days of age, and ewes are milked twice per day from 24 hours
postpartum until a test day on which their total daily milk yield is less than .5 lb. The MIX
system is as follows: for the first 30 days postpartum, lambs are separated from their dams
overnight, ewes are milked once per day in the morning, and lambs are returned with their dams
for the day; lambs are weaned onto dry diets at approximately 30 days of age, and after their
lambs are weaned, ewes are milked twice per day until a test day on which their total daily milk
yield is less than .5 lb.
Data were analyzed with the General Linear Models Procedure of the Statistical Analysis
System. For lamb growth traits, models included the effects of breed group, sex, birth type, dam
age, year of record, and two-way interactions. Models for reproductive traits included the effects
of breed group, ewe age, year of record, and two-way interactions. Lactation models include the
effects of breed group, weaning group, ewe age, year of record, and two-way interactions.
Results and Discussion
Growth. Tables 1, 2, and 3 present birth, weaning, and market weights for various breed
groups of lambs. When the information in all three tables is taken together, lambs with 1/2 or
greater East Friesian breeding tend to have greater birth (+.76 lb.) and weaning (+1.98 lb.)
weights than lambs of 1/2 or greater Lacaune breeding. However, market weights show the