BULLETIN 996, U. S. DEPARTMENT OF AGRICULTURE. 

 Table 3. — Effect of age of ewes on 'per cent of lambs dropped in experimental flocks. 



Age of ewes. 



Cases of 

 lambing. 



Lambs 

 dropped. 



Age of ewes. 



Cases of 

 lambing. 



Lambs 

 dropped. 



years. 

 2 . 



79 

 63 

 67 

 62 



Per cent. 

 111.4 

 123.8 

 143.3 

 143.5 



Years. 

 6 



49 



35 



22 



8 



Per cent. 

 161.2 



3 .. . 



7 



142.8 



4 



8 



113. 6 





9 



162. 5 





. 





TWIN PRODUCTION AS AFFECTED BY BREED OF EWE. 



Evidence as to inheritance of fertility makes it appear that vari- 

 ous breeds or strains have each an inherited limit of fertility and that 

 the obtaining of the full possibility in any one season will be deter- 

 mined by the extent to which the conditions and management favor 

 the full utilization of the inherited capacity. 



Records of actual returns from 189 flocks representing 9 breeds for 

 the seasons of 1919 and 1920 were obtained by the Animal Husbandry 

 Division through the kindness of breeders who reported. The aver- 

 age per cent of lambs in proportion to ewes, lambing in the spring, is 

 shown below, also the separate record of the 2-year-old ewes (drop- 

 ping lambs the first time) and the highest flock average reported for 

 each breed. The table gives the average of the two seasons' reports. 

 The high return for the breed is for a single season. 



Table 4. — Record of lamb crops, by breeds, from 189 flocks. 

 [Average of seasons 1919 and 1920.] 





Flocks. 



2-year-old ewes. Aged ewes. 



Total ewes. 



Highest flock. 



Breed. 



Ewes. 



Lambs 

 dropped. 



Ewes. 



Lambs 

 dropped. 



Ewes. 



Lambs 

 dropped. 



Ewes. 



Lambs 

 dropped. 





Number. 

 26 

 11 

 18 

 27 

 26 

 16 

 25 

 16 

 24 



Number. 

 215 



40 



96 

 138 

 549 



91 

 167 



84 

 186 



Per cent. 

 146 

 145 

 144 

 143 

 139 

 135 

 . 134 

 123 

 111 



Number. 

 566 

 106 

 214 

 378 

 857 

 190 

 402 

 184 

 667 



Per cent. 

 163 

 161 

 156 

 153 

 148 

 148 

 154 

 149 

 125 



Number. 

 7S1 

 146 

 310 

 516 

 1,406 

 281 

 566 

 268 

 853 



Per cent. 

 158 

 157 

 152 

 151 

 144 

 144 

 149 

 141 

 122 



Number. 

 6 



11 

 6 

 6 

 6 



23 

 6 

 8 

 9 



Per cent. 

 200 





191 



Oxford 



200 





200 





200 





200 





183 





200 



Rambouillet 



177 



TWIN PRODUCTION AS AFFECTED BY SIRE. 



A study of 334 cases of lambing from the services of 5 rams, none 

 of which were used less than three seasons or on less than 20 ewes, does 

 not indicate any important variation in proportions of twins that can 

 be attributed to the sire. Such differences as were shown in the 

 average number of lambs per service for each sire appeared to be due 

 to differences in the ewes to which they were bred. Records of 380 

 lambings from services of 8 different sires were studied in relation to 



