Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

relay system has an advantage in that ewes coming into heat have access
to a fresh ram, On the other hand Lindsay and Robinson (1961la) found
that more ewes were served per ram in mating groups where at any one
time three rams were used rather than one., This could be important for,
in addition to achieving a more uniform distribution of matings over

the ewes in oestrus at a particular time, it also helps to overrule any

incompatibilities that might exist between particular males and females.

The results in group 3 are from a relay system employing three
rams together, The advantages accruing to this latter system as opposed
to those discussed are statistically significant (P<0,05) in terms of
the percentage conceptions at the induced oestrus. This three ram re-
lay system apparently incorporates the advantages of the other two

systems, while excluding the major disadvantages.
SUMMARY

While no clear effect of the timing of injection of PMS was evident
in the results, the administration of PMS did significantly enhance the
response to treatment, A significant difference is shown in favour of
joining the rams at pessary removal, Employing a group relay ram system
proved significantly superior to the other systems of ram management
studied,

REFERENCES
Gordon, I. (1958b) - Studies in the Extra-seasonal Production of Lambs -
J, Agric. Sci,, 50:: 152,

Crowley, J.P. (1964) - The Extension of the Breeding Season in Sheep -
Proc. 5th Int. Cong. Anim Reprod. A.I. (Trento) 2 : 378.

Robinson, T.J. (1965b) - Use of Progestegen Impregnated Sponges Inserted
Intravaginally or Subcutaneously for the Control of the Oestrus Cycle
in the Sheep - Nature (Lond). 206 : 39,

Roberts, E.M. & Edgar, D.G. (1966b)., - Timing of Injection of Pregnant
Mares Serum for the Anoestrous Breeding of Ewes - Nature (Lond). 212 :1048,

Lindsay, D.R. & Robinson, T.J. (1961la) - Studies on the Efficiency of
Mgting in Sheep; the Effect of Paddock Size on the Number of Rams -
To Agric. SCio 57 - 1370

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