Types and Market Classes of Live Stock 



199 



proximation by using purebred dairy bulls to grade up the ordinary 

 dairy cows of the country. There is no good argument in behalf of 

 keeping any except a purebred dairy bull at the head of any dairy herd. 

 No progressive dairyman will take chances in raising a heifer calf for 

 milk purposes whose sire is either a beef bull or a mongrel. The 

 necessity for using purebred sires to breed to common cows and the 

 financial advantage of such a policy was pointed out in Chapter IX, 

 in which the breeding of beef cattle for the market was discussed. 

 The arguments there presented apply with equal force to the breeding 

 of dairy cattle. 



Tests which strikingly illustrate the effect of a purebred sire in 

 improving a herd of scrub dairy cows have been conducted at the Iowa 

 Station^ by Kildee and McCandlish. The scrub cows were mated 

 with good purebred Holstein, Guernsey, and Jersey bulls, and the 

 daughters were in turn mated with similar bulls. The results presented 

 in the following table show the average yearly production of the 

 original scrub cows and the greatly increased ability of their daughters 

 and granddaughters. All were fed and cared for alike, and no animals 

 were weeded out during the experiment, so that the improvement 

 secured can be credited only to the use of good purebred sires: 



Average production by scrub cows and by their daughters and granddaughters sired by 

 purebred dairy bulls 



Scrub dams .... 



Daughters 



Granddaughters 



Milk 

 Pounds 



3,660 

 5,999 

 8,402 



Fat 

 Pounds 



172 

 261 

 358 



Increase over original 

 scrub cows 



Milk 

 Per cent 



Fat 

 Per cent 



64 

 130 



52 

 109 



The half-blood daughters, carrying 50 per cent of improved breed- 

 ing, showed an increase of 52 per cent in butter-fat production as com- 

 pared to their scrub dams. The granddaughters, carrying 75 per cent 

 of improved breeding, showed an increase of 109 per cent in butter-fat 

 production as compared to their scrub grandams. In other words, the 

 production of this herd was doubled in two generations through the 

 use of good dairy sires. 



J. C. McDowell of the Dairy Division, U. S. Department of 

 Agriculture, states: ^ "A scrub cow is almost worthless because she 

 yields no profit. A scrub bull is worse than worthless because he 

 quickly drags the remainder of the herd down to his low level. In a 

 year a scrub cow produced 146.8 pounds of butter-fat. Her daughter, 



iJowa Buls. 165, 188. 



2U. S. Dept. Agr. Yearbook, 1920, p. 410. 



