Calves Born per Cow, Mortality, Sex Ratios, and Sterility Rates 



Mortality and culling rates for young stock were established on farms 

 operating under good management. If all potentially fertile female calves 

 were raised for replacements, cow numbers could be increased at the annual 

 rate of about 100 per 1,000 cows. Considering the annual rate of increase 

 from the viewpoint of possibilities for culling and herd improvement, it 

 would be possible to maintain a stable cow population and to cull about 

 100 replacements per 1,000 cows annually. 



Incidence of Disease, Herd Life, Age at Disposal, and Life Expectancy 



Purchased cows are no more prone to disease than raised cows. Of 

 herd removals of purchased cows, 43 percent were removed for reasons of 

 sterility, brucellosis, and udder trouble. Of the raised cows that were culled, 

 40 percent were removed for the same reasons. A study of a group of herds, 

 some composed of all raised cows and some composed of raised and pur- 

 chased cows, indicated that the number of removals because of disease 

 was not disproportionate between the two types. On farms with all raised 

 cows, 41 percent of the culled cows were removed because of udder trouble, 

 sterility, and brucellosis. On farms with some purchased animals, 37 per 

 cent of the culled cows were removed for these reasons. 



Purchased cows have a longer total productive life than raised cows. 

 The average age of disposal for nondairy purposes for purchased cows was 

 7.06 years, while that of cows raised on the farm was 5.74 years. 



The life expectancy of dairy cows decreases gradually with the in- 

 crease in age. This gradual decrease helps to explain the longer herd life 

 of purchased cows. The life expectancy of New Hampshire dairy cows 

 compares favorably with that estimated for cows in other areas of the 

 United States. 



Yields for Hay, Silage Crops, and Pasture 



A careful study of the farm records for sample dairy farms reveals 

 that differences in yields among crops were closely associated with man- 

 agement ability, the price of livestock, and supplies of feed. Both per acre 

 yields and total tons of hay equivalent harvested were larger for farmers 

 who did not buy replacements than for farmers who bought some of 

 their replacements. Total forage consumed per animal unit was 5.2 tons 

 per year on the farms with no purchased replacements and 5.8 tons on 

 the farms whose operators bought some replacements. On both types of 

 farms, some additional forage was purchased. 



Labor Available for Chore Work, and Requirements 

 for Cows and Young Stock 



The labor used on the dairy herds of farmers who raised all their 

 replacements and of those who bought replacements did not differ sig- 

 nificantly. Standard labor requirements for cows and young stock were 

 summarized from reports of previous studies in New Hampshire. 



Available Barn Space and Utilization by Cows and Heifers 



Most of the sample dairy farms visited had conventional stanchion- 

 type barns. Only about 10 percent of the farms fully utilized this space 



