16 EXPERIMENT STATION BULLETIN 351 



lift the load but it has proven subject to rather serious difficulty such as 

 excessive drain on the battery and failure of the starter to disengage. A 

 power-driven hoist is a necessary time saver and further experimenting 

 will be continued on this mechanism by making a direct connection 

 through some part of the engine or final drive. 



Time trials are to be conducted during the 1943 harvest season in or- 

 der to determine the amount of time and labor saved by use of the buck 

 rake. A publication showing construction details and other pertinent 

 information will be available to New Hampshire farmers in time to con- 

 struct a similar rake for their own use on the 1944 hay crop. 



E. W. Foss, P. T. Blood, M. F. Abell 



DAIRYING 



Breed Analyses of Herd Management Practices 



A study of the lactation records of more than 4000 cows owned by 

 farmers who are members of the New Hampshire Dairy Herd Improve- 

 ment Association has been continued. The study involves five breeds of 

 dairy cattle including (in order of number of cows) Holstein, Guernsey, 

 Ayrshire, Jersey, and Milking Shorthorn. The data were tabulated to 

 facihtate a statistical analysis for each breed on the basis of twelve distinct 

 comparisons involving production, date of freshening, length of lactation, 

 grain-milk ratio, and age. 



Conclusions based on completed analysis indicate breed differences 

 in the response of dairy cows to certain management factors. For in- 

 stance, in studying the influence of the calving month on production. Jer- 

 seys showed no significant relation between these two factors, whereas 

 the other four breeds gave a picture resembling that commonly found by 

 other investigators, with the midsummer freshening causing lower lacta- 

 tion yields and late fall and winter freshenings in higher yields. Environ- 

 mental changes brought about by seasonal variations did not influence 

 milk production with Jerseys as it did with other breeds. 



In comparing the length of lactation with milk production (4 per 

 cent F. C. M.), Holsteins showed greater response in milk yield to long- 

 er lactation periods than did the other breeds. 



Another indication of breed differences was observed as a result of 

 comparing the milk-grain ratio with the yield of milk (4 per cent 

 F. C. M.). Ayrshires, Guernseys, and Holsteins showed positive correla- 

 tion between increased production and a widening ratio of milk to con- 

 centrates, whereas Jerseys showed a negative correlation. 



The length of lactation was not influenced significantly by the month 

 of freshening. 



In studying the effect of the month of calving on the ratio between 

 the grain fed during lactation and the lactation milk yield, the freshening 

 months of June, July, August, and September each showed low returns 

 of milk for grain fed for at least four of the five breeds studied. For July, 

 calving comparisons were significantly low, and in August four were 

 significantly low. Greatest returns of milk in relation to amount of grain 



