The data, sources, and calculations used in the Problems Inherent in Dairy Production infographic
"A cow typically remains in the dairy herd until about 5 years of age, although many cows are capable of remaining productive in the herd for 12 to 15 years. Following birth, the calf is usually removed from her dam after only a few hours."
...
"Each period of production or lactation lasts for 12 to 14 months or longer and spans the time period from calving to dry-off, which is when milking is terminated about 60 days before the next anticipated calving. Thus, cows are bred while they are producing milk, usually beginning at about 60 days after calving to maintain a yearly calving schedule. Indeed, dairy producers attempt to get cows bred precisely during the time they are producing the most milk, which has negative implications for cow fertility. Following the 2-month dry period, the cow calves again and lactation cycle begins anew. Cows average about 2.5 lactations, although many remain productive considerably longer. Cows tend to survive longer in less-intensive pasture systems than when on concrete all of the time. The leading reasons cows leave the dairy herd are low production, infertility, mastitis (inflammation of the udder), and lameness."
"We evaluated how the behavioural and heart rate response of dairy cows and calves to mutual separation was affected by two factors: the age of the calf at separation (1, 4 and 7 days) and the presence or absence of visual and auditory contact between the mother and her calf after separation."
...
"The results indicate that the response of cows and calves to separation is more intense and lasts longer when separation is delayed and that this effect is prolonged and further intensified when they are allowed visual and auditory contact after separation. On the other hand, delayed separation influences later social behaviour of calves in a way that may enhance their coping abilities."
"Maximum lifespan in domestic cows may exceed 20 years. However, lifespan is often limited by human culling."
Range lifespan
Status: captivityTypical lifespan
Status: captivity>20 (high) years 20 (high) years
Cattle Inventory by Class and Calf Crop — United States: January 1, 2014 and 2015 Class 2014 2015 Cows and heifers that have calved ... ... Milk cows 9,207,600 9,306,900 Heifers 500 pounds and over ... ... For milk cow replacement 4,548,700 4,615,400 Source: Cattle, 01.30.2015 (NASS) [PDF]
The goal calving interval of a dairy cow is 12 months[1], so it can be assumed that all cows in the dairy herd that have given birth at least once will then give birth to a calf each year afterwards until they are culled. It can also be assumed that half of these calves will be male.
9,306,900 dairy cows * 1 calf born/dairy cow / year = 9306900 calves born/year
9,306,900 calves/year * year/31,536,000 seconds = 0.30 calves/second = 1 calf/3.39 seconds
1 calf/3.39 seconds * 1 bull calf/2 calves = 1 bull calf/6.78 seconds
Federally Inspected Number of Head Slaughtered and Percent by Classification and Month — United States: 2014 and 2013 Total Classification 2014 Total 2013 Total Calves and vealers 557,600 751,000
557,600 calves/year * year/31,536,000 seconds = 0.02 calves/second = 1 calf/56.56 seconds
9,207,600 calves * 1 bull calf/2 calves = 4,603,800 bull calves
557,600 vealers/4,603,800 bull calves = 12.11%
Federally Inspected Number of Head Slaughtered and Percent by Classification and Month — United States: 2014 and 2013 Total Classification 2014 Total 2013 Total Dairy cows 2,815,600 3,124,900
2,815,600 cows/year * year/31,536,000 seconds = 0.09 cows/second = 1 cow/11.20 seconds
