32 AGRICULTURE HANDBOOK NO. 3 09, U.S. DEPARTMENT OF AGRICULTURE 



successive years. Others may go 

 through periods of 4, 8, or 10 weeks 

 when the does will not conceive or 

 the bucks are sterile. Extreme 

 cases in which no young are pro- 

 duced for 4 to 5 months may occur 

 in herds where bucks and does are 

 out of condition because the ration 

 has been inadequate in quality or 

 quantity, or both. If the herd has 

 been properly cared for, most bucks 

 and does should complete the bar- 

 ren period in 4 to 6 weeks. 



Because does and bucks vary so 

 much with respect to breeding, you 

 may well consider this factor care- 

 fully. In selecting breeding stock, 

 make your choice from offspring 

 of parents that produce regularly. 



Age. — Young does may not be 

 sexually mature at the time of serv- 

 ice, and old does may have passed 

 their period of usefulness and fail 

 to conceive. Do not attempt the 

 first mating until the does are sexually 

 mature and properly developed; 

 the proper age is discussed on 

 page 29. 



Does should reproduce satisfac- 

 torily as long as they maintain good 

 physical condition and properly 

 nurse their litters. Retain them if 

 younger and better stock is not 

 available for replacements. In 

 commercial herds, does that are 

 properly cared for should produce 

 litters until they are 2K to 3 years 

 old. An occasional individual rab- 

 bit may reproduce satisfactorily 4 

 to 6 years, or longer. 



Physical Condition. — Rabbits 

 that go "off feed," go into a pro- 

 longed or heavy molt, become 

 abnormally fat or thin, or become 

 out of condition for any reason, 

 may have their reproductive powers 

 impaired. The percentage that will 

 conceive will be low, since they may 

 become temporarily sterile. 



Disease. — Never mate rabbits 

 when they show any symptoms of 

 disease. Remove such animals 



from the herd and hold them in 

 quarantine until they recover. 



Artificial Insemination 



Artificial insemination has been 

 practiced with rabbits for experi- 

 mental purposes, but has not been 

 applied to commercial breeding to 

 any extent. 



The semen from bucks averages 

 about 0.5 cc. in volume, with a 

 range of 0.1 to 6 cc. It contains 

 about 700 million to 2 billion sperm 

 per cubic centimeter. The total 

 number of sperm per ejaculate 

 averages 250 million, which does not 

 mean a great deal, because of the 

 extreme variation. The total num- 

 ber of sperm per ejaculate may 

 range from 10 million to 12 billion. 



Semen is collected from the 

 bucks by means of an artificial 

 vagina. After the artificial vagina 

 has been prepared, the collection 

 is made by using a doe for a 

 mounting animal. The doe is taken 

 to the buck's cage and when the 

 buck mounts, the artificial vagina 

 is placed between the buck and the 

 doe. "Wlien the buck locates the 

 artificial vagina, he will ejaculate 

 into the open end with the same 

 behavior as when breeding natu- 

 rally. The operator must be alert 

 to prevent the buck from breeding 

 the doe. After the buck has been 

 trained, a dummy made of a 

 stuffed rabbit skin may be sub- 

 stituted for the mounting doe. If 

 the ejaculate contains a clear gela- 

 tinous plug, it should be removed 

 from the liquid portion of the 

 semen. 



A simple insemination tube has 

 been described for insemination of 

 the does. It consists of a glass 

 tube and rubber bulb similar to a 

 medicine dropper, with the last 

 half -inch bent at a 30° angle. The 



