254 Maine Agricultural Experiment Station. 1919. 



Transmitting Qualities for Milk Production, Butter-Fat 



Percentage and Butter-Fat of Guernsey Sires to 



Their Sons. 



In the report of last year 3 three tables were given to enable 

 the breeder to determine the worth of Guernsey sires for milk 

 production, butter-fat percentage and butter-fat.* 



The tables were made by determining the milk production, 

 butter- fat percentage and butter- fat corrected for age. For 

 the cow with more than one record the records were each cor- 

 rected for age and averaged and this average used for that cow. 

 In a similar paper on the Jersey sires 4 the record nearest 8 years 

 was chosen for correction if the cow had two or more year 

 records. The difference in arriving at the end results is obvi- 

 ous. Each method has its merits. The work of calculation for 

 the Guernsey sires was completed before it was discovered that 

 this difference in method existed in approaching the end results. 

 For the sake of uniformity and to enable the results to be com- 

 pared it was therefore determined to do the work for the 

 Guernsey breed all over again employing the method used for 

 the Jersey breed. This has been done. The records published 

 for the Guernsey sires in last year's report use the average pro- 

 ductions of the daughters with two or more records in deter- 

 mining a bull's worth. The records for the Guernseys in this 

 report and as will be hereafter published use the record nearest 

 8 years of age for those daughters which have two or more 

 records. Either method is correct and according to the prefer- 

 ences of the readers have their supporters. 



It is possible to determine what the transmitting qualities 

 of a sire to his sons may be by determining for those sons what 

 their daughters did in the way of milk production, butter-fat 



3 Gowen, John W., Report of Progress on Animal Husbandry Inves- 

 tigations in 1917. In 1918 Maine Agricultural Experiment Station 

 Annual Report, pp. 205-228, 1918. 



*These tables contained all Guernsey sires with 7 or more tested 

 daughters from advanced registry dams. The tables and the text matter 

 pertaining thereto were copied in their entirety by the Hoard Dairy- 

 man, 3. 



4 Studies in Milk Secretion. VII. Transmitting Qualities of Jersey 

 Sires for Milk Yield, Butter-Fat percentage and Butter-Fat in 1919, 

 Maine Agricutural Experiment Station Annual Report, pp. 89-204, 1919. 



