January, 1938] Dairy Herd Replacements 19 



slaughter purposes and not to other farmers or to cattle dealers for con- 

 tinued production to obtain a more attractive price. It would seem, 

 then, that cows sold for slaughter should fall into a ditferent category 

 from those sold for production, and yet some of the reasons for selling 

 are common to both groups but differ in times mentioned. Breeding 

 and calving troubles accounted for more than one-fourth of the 297 

 cows slaughtered for which detailed information was tabulated. The 

 greater part of this was of the nature of Bang's disease. Only one- 

 fifth were slaughtered because of old age. Udder trouble accounted for 

 17.5 per cent of the cows slaughtered, usually taking the form of one or 

 more defective quarters. Undoubtedly the greater part of this was 

 mastitis. Only 25 per cent of the cows slaughtered because of udder 

 trouble were purchased cows, compared with 49 per cent of those sold 

 because of breeding and calving troubles. Thus, proportionately more 

 of the raised cows were sold because of udder trouble and proportion- 

 ately more of the purchased cows were sold because of breeding trouble. 

 Only 17 cows were said to be .slaughtered because of culling out. 



About as large a proportion of the cows sold for slaughter was raised 

 on the respective farms as in the case of those sold for production. Thir- 

 ty-two per cent of those slaughtered were purebreds compared with 28 

 per cent of those sold for production. Slaughtered cows averaged more 

 than one year older, and although they attained the same maximum pro- 

 duction about 30 days after freshening, they had on the average a short- 

 er lactation period. In general slaughtered cows were of poorer qual- 

 ity but perhaps to a lesser degree than might be expected. 



Disease and Replacement Practices 



Another important reason given by farmers for raising their own re- 

 placements was that it is easier to keep the herd free from contagious 

 diseases. The three diseases most prevalent among dairy cows in the 

 northeast are bovine tuberculosis. Bang's disease or contagious abor- 

 tion, and mastitis. 



The Tuherculm Test. Although bovine tuberculosis was practically 

 eradicated from New Hampshire herds before the period of this survey, 

 some information was obtained for general knowledge concerning the 

 results of the test, and for the purpose of observing the relation of re- 

 placement methods to the prevalence of this contagious disease. These 

 data were employable for 164 of the 200 herds surveyed, and included 

 2837 cows tested (Table 12). Fifty-nine per cent of these cows were 

 raised on the respective farms where tested. Forty per cent of all the 

 cows tested were classed as reactors for which state and federal indem- 

 nity has been available since 1917. Proportionately more of the pur- 

 chased cows reacted than of those raised, the percentages being 54 and 

 29 respectively. In general, losses declined with an increase in the per 

 cent of the herd that was raised. More than two-thirds of the 51 herds 

 which consisted only of cows raised proved to be free of tuberculosis ; 

 whereas, in the case of herds which were partly raised and partly pur- 

 chased, only a small percentage was clean. 



There was a tendency for herds tested in the later years to involve 

 greater losses (Table 13). This trend is associated with replacement 



