The objective of this study was to estimate the value of pregnancy for dairy cows. Effects of the stage of gestation, stage of lactation, lactation number, milk yield, milk price, replacement heifer cost, probability of pregnancy, probability of involuntary culling, and breeding decisions were studied. A bioeconomic model was used, and breeding and replacement decisions were optimized. A general Holstein herd in the United States was modeled. The average value of a new pregnancy was $278. The value of a new pregnancy increased with days in milk early in lactation but typically decreased later in lactation. Relatively high-producing cows and first-lactation cows reached greater values, and their values peaked later in lactation. The average cost of a pregnancy loss (abortion) was $555. The cost of a pregnancy loss typically increased with gestation length. Sensitivity analyses showed that an increased probability of pregnancy, an increased persistency of milk yield, and a smaller replacement heifer cost greatly reduced the average value of a pregnancy. The value of a new pregnancy was negative for relatively high-producing first-lactation cows when persistency of lactation and the probability of pregnancy were increased. Breeding was delayed when the value of pregnancy was negative. Changes in milk price, absolute milk yield, and probability of involuntary culling had less effect on the value of pregnancy. The value of pregnancy and optimal breeding decisions for individual cows were greatly dependent on the predicted daily milk yield for the remaining period of lactation. An improved understanding of the value of pregnancy may support decision making in reproductive management when resources are limited.

The objective was to describe the dynamics of culling risk with disposal codes for Holstein dairy cows reported by herds enrolled in the Dairy Herd Improvement program. Dairy producers could report 1 of 9 possible disposal codes or forego reporting a code. After edits, 3,629,002 lactation records were available for cows calving between 2001 and 2006 in 2,054 herds located in 38 states primarily east of the Mississippi river. The distribution of culled cows by disposal code was estimated by parity, days after calving, pregnancy status, cow-relative 305-d mature equivalent milk yield, herd-relative 305-d mature equivalent milk yield, and season. Of all herds, 57% reported all 8 different disposal codes excluding the codes dairy purposes and reason not reported. Hazard (risk) functions were calculated by parity, from 1 to 520 d since calving for open cows and from 1 to 280 d since conception for pregnant cows. Annualized live culling rate and death rate (reported code was death) were 25.1 and 6.6%, respectively. The primary disposal code was died (20.6% of all culling), followed by reproduction (17.7%), injury/other (14.3%), and low production and mastitis (both 12.1%). The risk of culling with various disposal codes varied with stage of lactation. Died and reproduction were the most frequently reported codes for cows leaving the herd during early and late lactation, respectively. Early lactation was also a critical period for culling with the disposal codes injury/other and disease, and the risk increased with days after calving for the codes low production and reproduction. The risk of culling with the disposal code died showed the greatest seasonal pattern with increased risk of death in spring and summer. A negative association was found between annualized live culling and death rates within herds. Compared with open cows, pregnant cows had a lower risk of culling with all reported disposal codes. In addition, the risk of culling was lower in high-producing cows with all disposal codes. In conclusion, the risk for culling by disposal code varied by parity, stage of lactation, season, pregnancy status, and milk yield.

The objective of this study was to compare the economic outcome of reproductive programs using estrus detection (ED), timed artificial insemination (TAI), or a combination of both (TAI-ED) using a stochastic dynamic Monte-Carlo simulation model. Programs evaluated were (1) ED only; (2) TAI: Presynch-Ovsynch for first AI, and Ovsynch for resynchronization of open cows at 32 d after AI; (3) TAI-ED: Presynch-Ovsynch for first AI, but cows underwent ED and AI after first AI, and cows diagnosed open 32 d after AI were resynchronized using Ovsynch. Evaluated were the effect of ED rate (40 vs. 60%; ED40 or ED60), accuracy of estrus detection (85 vs. 95%), compliance with the timed AI protocol (85 vs. 95%), and milk price ($0.33 vs. 0.44/kg). Conception rate to first service was set at 33.9% and then decreased by 2.6% for every subsequent service. Abortion was set at 11.3%. Cows were not AI after 366 d in milk, and open cows were culled after 450 d in milk. Culled cows were immediately replaced. Herd size was maintained at 1,000 cows, and the model accounted for all incomes and costs. Simulation was performed until steady state was reached (3,000 d), and then average daily values for the subsequent 2,000 d were used to calculate profit/cow per year. Net daily value was calculated by subtracting the costs (replacement, feeding, breeding, and other costs) from the daily income (milk sales, cow sales, and calf sales). The ED40 models resulted in greater profits than the TAI-85 model but lower profits than the TAI-95 model. Both ED60 models resulted in greater profits than the TAI-95 model. Combining TAI and ED increased profits within each level of accuracy or compliance. Adding TAI to ED would increase overall profit/cow per year by $46.8 to $74.7 with 40% ED, and by $8.9 to $30.5 with 60% ED. Adding ED to TAI would increase profit/cow per year by $64.2 to $99.4 with 85% compliance and by $31.8 to $59.7 with 95% compliance. Although combining TAI and ED increased profits within each level of accuracy or compliance, when evaluated separately, ED60 with 95% accuracy or TAI with 95% compliance were as profitable as or more profitable than TAI-ED with low ED, accuracy, or compliance. Therefore, producers can improve their profits by combining TAI and ED as reproductive management; however, if a herd can achieve high ED with high accuracy or have high compliance with injections, using only ED or TAI might be more profitable than trying to do both.

The average productive lifespan is approximately 3 to 4 years in countries with high-producing dairy cows. This is much shorter than the natural life expectancy of dairy cattle. Dairy farmers continue to cull cows primarily for reasons related to poor health, failure to conceive or conformation problems prior to culling. These reasons may indicate reduced welfare leading up to culling. Improvements in health care, housing and nutrition will reduce forced culling related to these welfare reasons. However, productive lifespan has remained similar in decades, despite large improvements in cow comfort and genetic selection for the ability to avoid culling. On the other hand, genetic progress for economically important traits is accelerating within the last decade, which should slightly shorten the average economically optimal productive lifespan. A major driver of productive lifespan is the availability of replacement heifers that force cows out when they calve. The average productive lifespan could be extended by reducing the supply of dairy heifers, which would also have benefits for environmental sustainability. Improvements in culling decision support tools would strengthen economically optimal replacement decisions. In conclusion, major factors of the relatively short productive lifespan of dairy cows are welfare-related, but other economic factors like supply of heifers, genetic progress and non-optimal decision-making also play important roles.

Widespread commercial application of sexed semen is expected within the next decade because of continued improvements in fertility of sexed semen and sorting capacity. The objective of this study was to explore the potential impact of widespread application of sexed semen on the structure of the dairy industry in the United States. Historically, female offspring from all heifers and cows were needed to produce enough dairy replacement heifers to replace culled cows. The use of sexed semen allows for a decoupling of breeding decisions necessary to obtain an adequate supply of dairy replacement heifers from those needed to achieve pregnancies needed to start new lactations. Application of sexed semen allows dairy producers to select among their herds' potential dams and produce dairy replacement heifers from only the genetically superior animals. The rate of genetic progress is expected to increase, but not more than 15% of the rate of gain accomplished through sire selection achieved through conventional (nonsexed) artificial insemination breeding. The supply of dairy replacement heifers is expected to grow to meet and temporarily exceed current demand, resulting in reduced prices for dairy replacement heifers. Consequently, herd turnover rates are expected to increase slightly, and herd expansions may accelerate. The rate of consolidation of dairy farms is expected to increase. Widespread application of sexed semen may temporarily increase the supply of milk, which would result in lower milk prices. The cost of milk production will be reduced as well. Many breeding options exist for the genetically poorer cows in the herd. The optimal breeding mix depends on the value of the various kinds of calves that could be produced. More crossbred calves for beef production may be produced; however, a market for these crossbred calves is not well established. Increased specialization is expected with more dairy producers deciding not to raise their own heifers but to purchase replacements. Other dairy farms might specialize in producing genetically superior dairy replacement heifers for sale. Depending on the value of calves not raised for replacements, artificial insemination organizations might market beef conventional semen or beef male sexed semen to dairy farms. The use of sexed semen should lower the cost of progeny-testing programs and embryo transfer and enhance the value of genetic markers. Eventually, the economic benefits from the use of sexed semen will be passed on to consumers.