510 



GENETICS IN RELATION TO AGRICULTURE 



more the decisive standard of excellence, a fact which is reflected in the 

 establishment of advanced registry records by pure-bred dairy cattle 

 associations for those animals which prove of superior performing or 

 breeding ability. Many experiment stations have enthusiastically 

 recommended the use of pure-bred sires in building up dairy herds, 

 a few have conducted investigations for the purpose of determining 

 precisely how much improvement may be expected from the use of 

 such sires. An investigation of this kind at the Iowa Station has pro- 

 ceeded far enough to warrant a preliminary report. For this investiga- 

 tion seven cows, six heifers, and one young bull were purchased in an 

 isolated region of Arkansas where it was practically certain that no 

 pure-bred bulls had ever been used. These were developed at the 

 station, and their records are available for comparison with those of 

 their daughters which have been sired by Guernsey, Holstein-Friesian, 

 or Jersey bulls. In Fig. 196 are shown the results of grading two gen- 

 erations to pure bred 



TABLB LXVIII. COMPARISON OP A SCRUB Cow, 



No. 52, WITH HER DAUGHTER, No. 69, SIRED 



BY A HOLSTEIN-FREIBIAN BULL (Data of 



Kildee and McCandlish) 



stein-Friesian bulls. The 

 first generation of grading 

 has given a heifer which is 

 intermediate in most char- 

 acters between its dam and 

 the general type of Hol- 

 stein-Friesian cow. She, 

 however, lacks the char- 

 acteristic color markings of 

 the Holstein-Friesian, a 

 fact which obscures some- 

 what her resemblance to 

 that breed's type. The 

 second generation calf, her 

 daughter, however, pos- 

 sesses characteristic Hol- 

 stein-Friesian markings and would pass for a very fair specimen of the 

 breed. The important consideration, however, is the comparative 

 excellence of these animals in milk and butter fat production. The 

 data relative to this question are given in Table LXVIII. The most 

 notable feature in these records is the increase of 64 per cent, in average 

 net returns. 



Table LXIX has been so compiled from the data of Kildee and Mc- 

 Candlish as to give a general re'sume' of their investigations. The cows 

 have been divided into three lots according to the kind of sire used in 

 grading. In the first lot scrub cows are compared with their daughters 

 which were sired by a Holstein-Friesian bull; in the second lot the scrubs 



