HYBRIDIZATION IN ANIMAL BREEDING ; 511 
Taste LXIX.—Comparative Recorps or Scrus Darry Cows anp THER GRADE 
Dauveuters (Data of Kildee and McCandlish) 
Average yearly records ee cents inclease 
No No. of grades over scrubs 
Let ot etree lle penedey | Powe Pounds | Pound 
ea ion ounds ounds Net ounds ounds Net 
WS | periods La of pubes pea acl or putear eae 
SChUDS sere yee era 4 17 | 3,156.6 | 158.10 |$18.42 
Scrubs X Holstein.| 4 12 | 5,428.5 | 230.10 | 23.86 | 71.90 | 41.50 29.9 
Scrubsee...5s-6 5 os 4 19 | 4,056.1 | 181.85 | 24.59 
Scrubs X Guernsey| 4 8 | 4,146.7 | 194.92 | 19.98 | 2.21 7.18 | —18.7 
Serubst:..4222 cass] 1 7 | 3,487.5 | 166.74 | 24.39 
Scrubs X Jersey...| 1 2 | 3,643.1 | 199.64 | 21.01 | 6.00 | 20.00 | —13.8 
which produced heifer calves to Guernsey bulls are compared with their 
daughters, and in the third lot a Jersey grade cow is compared with her 
scrub mother. 
This table must be interpreted with some care, because it suffers from 
the same fault which mars a large proportion of agricultural data; things 
are compared which are not directly comparable. In Table LXIX 
have been presented the indices which would have made it possible to 
evaluate these data with respect to milk production and butter-fat content, 
but the evaluation has not been made in this case. The comparison of 
scrub cows with their grade Holstein-Friesian daughters shows substantial 
increases in milk production, butter-fat production, and net returns, and 
this in spite of the fact that immature cows are compared with mature 
ones. The increases here are due to several things. The scrub cows of 
this lot were the most inferior of all, the Holstein-Friesian bull which 
was used probably came from better producing lines within his breed than 
did the bulls of the other breeds, and a more representative test has been 
made of the grade Holsteins than of either of the other two lots of grades. 
If proper allowance had been made for the immaturity of the Holstein 
grades, they would compare even more favorably with their dams. In 
the Guernsey class the average excellence seems to be somewhat lower 
than that of the dams. The scrub cows of this lot, however, were better 
producers than those of either of the other two lots. Moreover, the 
immaturity of the grades in this test has had more effect than in the 
Holstein class, because two of them are represented by first year records 
only. Three of them were sired by a Guernsey bull which had been 
loaned to the station, and he apparently was not a good sire of dairy 
quality. The fourth member of the lot was sired by a Guernsey bull 
belonging to the station and she showed an increase of over 100 per cent., 
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