Dairy Herd Management recently published a pair of articles (Get a handle on dystocia data and Every delivery is special) that discussed the need for record-keeping as part of a calving management program. I agree very strongly with the importance of data collection. Without accurate information about calving performance it is difficult to identify and address problems. However, I must respectfully disagree with Dr. Frank Garry, who recommends the use of a three-point scale for recording dystocia because we already have a five-point scale (Table 1) that has been used as the basis for the national calving ease genetic evaluation program since it began in 1978. The success of this program is demonstrated by the 26,001,868 calving records that dairy farmers have provided as of the August 2014 genetic evaluation run.

The dairy genetics community, including university and government scientists and the National Association of Animal Breeders, has been working to reduce rates of dystocia and stillbirth for almost 40 years. Predicted transmitting abilities calculated using data from dairies around the US have been included in the lifetime net merit index (NM$; http://aipl.arsusda.gov/reference/nmcalc-2014.htm) since 2003, and they receive 5% of the overall emphasis in the new 2014 NM$. Holstein Association USA's Total Performance Index (http://www.holsteinusa.com/genetic_evaluations/ss_tpi_formula.html) and Genex's Ideal Commercial Cow index (http://genex.crinet.com/news2304/GenexICCSub-IndexesTargetFiveManagementAreas) also include calving traits. We also exchange information about the genetic merit of Holstein bulls with US daughters with 15 other countries through the Interbull calving traits system. The recent base change shows favorable phenotypic trends for sire and daughter calving ease and sire stillbirth, but a slight increase in daughter stillbirth. Genetic merit for all traits improved, which will result in reduced dystocia and stillbirth (http://aipl.arsusda.gov/reference/base2014.htm).

The scale that Dr. Garry proposed for dytocia (http://www.dairyherd.com/dairy-news/Get-a-handle-on-dystocia-data-274684591.html) is similar to ours in many respects, but it does not include a way of identifying cows that had some difficulty during calving but were able to give birth without intervention. This may seem like a strictly academic argument, but it could cause problems for the national genetic evaluation program because scores that are coded using the same value do not mean the same thing on each scale. For example, a score of 2 on Garry's scale corresponds to a score of 3 on our scale, and a score of 3 on Garry's scale is a score of either 4 or 5 on our scale. Only scores of 4 and 5 are counted as difficult births when the calving ease breeding values are calculated, so if a herd reports dystocia on Dr. Garry's scale then their difficult births will not properly counted. This could introduce a bias into the genetic evaluations that would result in bulls receiving more favorable evaluations than they should.

Table 1. Description of the 5-point calving ease scale used for the national genetic evaluations and the number of observations in each category for the August 2014 run.

Numerical score

Description

Number of calvings

Percentage

1

No problem

19,510,718

75.04

2

Slight problem

3,142,633

12.09

3

Assistance needed

2,354,471

9.06

4

Considerable force required

656,607

2.53

5

Extreme difficulty or surgical intervention

337,439

1.30

The scale used to record stillbirth information (Table 2) is very similar to that recommended by Dr. Garry, and genetic evaluations for Holstein stillbirth have been available since 2006 in the US. It may be the case that not everyone keeps their records as well as they could, but it is not accurate to say that “Our industry...largely overlooks losses in the first 48 hours of life” (http://www.dairyherd.com/dairy-news/Every-delivery-is-special-274684231.html). About 1/3 of the calving records in the national database do not have a useable stillbirth code, but much of the missing data is in the historical data. Over the last 5 years fewer than 13% of records having missing stillbirth codes. There is room here for improvement, and we should work towards the goal of recording calving ease and stillbirth scores for all births.

Table 2. Description of the 4-point calving ease scale used for the national genetic evaluations and the number of observations in each category for the August 2014 run.

Numerical score

Description

Number of calvings

Percentage

0

Not reported

9,249,429

35.57

1

Calf born alive

15,750,780

60.58

2

Calf born dead

967,496

3.72

3

Calf born alive, but died within 48 h of birth

34,163

0.13

 

While the current discussion is focused on calving traits, it is important that occurrences of all common health disorders be entered into the on-farm record system. This will allow your veterinarian to help you better manage the health of your herd, and it will provide the data that we need to produce genetic evaluations that you can use to breed healthier – and more profitable – cows. There is no one answer to the challenge of keeping cows healthy, and we all need to work together so that the US dairy farmer can continue producing healthful, nutrient-dense food to feed a growing world.