170 Sheep-Farming 



at intervals of from fourteen to twenty-one days, 

 this gives a lambing time of the same length for the 

 ewes in lamb to service in the first or second heat 

 period after the ram is turned in. Considerable at- 

 tention is required for lambing ewes, especially for 

 those producing their first lambs. It is easier for 

 the shepherd to care for a number of ewes and young 

 lambs each day and night for a short time than to 

 have them come straggling along through several 

 weeks. The lambs are then uniform in size and get 

 well started under the same conditions. 



The number of lambs produced is determined by 

 the number of ova produced by the ewe. The ram 

 may sometimes be unable to produce spermatozoa 

 to fertilize the ovum, but there are no grounds for 

 believing that the reason for single or twin lambs lies 

 with the ram. It is true that the opinion is some- 

 times held that a ram that is a twin gets a larger 

 percentage of lambs than one that was a single 

 Iamb. The number of spermatozoa contained in the 

 seminal fluid at each service runs into the thousands. 

 Over-use or otherwise impaired conditions may lower 

 the number or suspend the production of the sper- 

 matozoa altogether, or it may cause them to be less 

 vigorous and active in traversing the passage toward 

 the ovum. For these reasons, the management of 

 the ram is an important factor. But it is most 

 improbable that if one spermatozoon should fertilize 

 an ovum, another ovum produced at the same time 



