Track difficult calving to gain profit
Data that reveal the expected calving difficulty for specific bulls within breeds can generate huge cost savings in the long run for all producers in the industry. Producers who have a handle on their herd's calving difficulty can make decisions that reduce financial loss.
Hard calvings bring financial loss later on
The cost of difficult calving in individual herds can be large depending on the 'degree' of difficult births. In a study conducted in three Colorado dairies with over 7,000 observed calvings, more than one half of the births by first-calf heifers required some assistance. Calves born with difficulty were 15 times more likely to also be stillborn than calves born without assistance, were 1.7 times more likely to experience a respiratory disease, 1.3 times more likely to have a digestive disease, and more than 6 times more likely to die within the first 120 days.
Difficult calving, especially of first-calf heifers, increases veterinary costs and farm labor, and reduces reproductive efficiency and milk production during the subsequent lactation. A study of more than 50,000 Holstein births in Spain revealed that first-calf heifers were 17% more likely to be culled after a difficult calving. Additionally, cows that experienced calving difficulty incurred replacement costs that were more than $100 per cow greater than herdmates.
Calving ease evaluations in the U.S.
USDA analyzes DHI records and then reports calving ease as the expected percentage of difficult births for heifers calving for the first time. Two distinct traits are analyzed that deal with calving ease: 1) Sire calving ease is the expected influence of the service sire, and 2) Daughter calving ease is the expected influence of sires on the calving ease of their daughters when they deliver their first calf.
Calving ease is traditionally recorded on a scale from 1 (no difficulty) to 5 (extreme difficulty). These definitions may vary slightly from herd to herd, but the important thing is that there is a clear break between calvings considered 1 to 3 versus the more difficult ones that are the 4s and 5s. The table accompanying this article reviews specific definitions used by several dairies enrolled in studies with the University of Minnesota.
Definitions for calving ease
|Calving Ease Score||Definition|
|1||No problem (unobserved or less than 2 hours)|
|2||Slight problem (greater than two hours, but no assistance provided)|
|3||Needed assistance (hand pull)|
|4||Difficult pull (obstetrical chains with considerable force)|
|5||Extreme difficulty (mechanical puller or cesarean section)|
Currently, the Holstein breed average for sire calving ease is 7.8%, which means that about 8 of every 100 first calvings are expected to have substantial difficulty (4 or 5). However, other studies have estimated the Holstein breed at higher rates between 11 and 29%! Why do some field studies report more calving difficulty than USDA? Remember, the data available to USDA includes only herds enrolled in DHI, and these herds tend to have a higher average plane of management and are more likely to use AI.
Calving ease of crossbreds
Crossbreds combining Jersey, Brown Swiss, and Holstein have been evaluated in the U.S. in recent years, and calving ease is improved when Jersey is used as the breed of sire. However, Jersey crossbred cows have negative attributes for confinement dairying, so it is important to thoroughly evaluate breeds before selecting breeds for a crossbreeding program.
Several European dairy breeds are widely used in the U.S. for crossbreeding, and the Swedish Red breed looks promising for calving ease. Calving ease for calves resulting from the use of Montbeliarde sires on Holstein dams were evaluated in two University of Minnesota dairies. Calving ease for the Montbeliarde x Holstein calves was not significantly different from pure Holstein calves, despite a heavier birth weight of the Montbeliarde x Holstein calves when born to Holstein cows in 2nd and later lactation. In the same dairies, Montbeliarde sires were also used on Jersey x Holstein crossbred cows, and the Montbeliarde-sired calves were similar to pure Holstein calves for both birth weight and calving ease in all lactations of dams.
Additional research is underway to learn more about total profitability of crossbreeding, in general, and the impact on calving ease, specifically. Calving ease, stillbirth, calf weight, and gestation length are all inter-related traits. For pure Holsteins and several beef breeds, lower birth weight of calves tends to reduce calving difficulty and stillbirth. The relationships of these traits for crossbred dairy cattle are still under investigation; however, relationships of birth traits in crossbreds could be different than pure Holstein calves because of the shape of the calves, especially in the shoulder region.
Calving ease is an economically important trait. The Net Merit index now places breed-wide emphasis on calving ease of Holsteins. Dairy producers should consider sire calving ease and daughter calving ease when selecting AI bulls, and keep individual animal records to track calving difficulty.