Weight tapes and hipometers are good ways to estimate the bodyweight of heifers. However, a new Canadian study shows they may be more accurate for certain age groups than others.

The study found that the bodyweight of Holstein heifers determined by heart-girth tape and hipometer came pretty close to the actual weight recorded by an electronic scale. That was particularly true for heifers between three and 15 months of age.

However, when it came to age groups outside that range, these tools just didn’t measure up to a scale. For instance, the weight of calves less than three months old determined with heart-girth tape was significantly less than that recorded by a scale. And for older heifers — those between 18 and 21 months old — the weights estimated by heart-girth tape and hipometer were significantly lower than the actual scale weight (For more details, please see the table below.)

Interpret these results with some caution, say the researchers. The number of heifers in some of the age groups was small, which makes it difficult to compare differences between the three measurement methods.

Overall, the study found that the weights estimated by the hipometer and heart-girth tape corresponded closely to the scale readings. However, to be the most accurate, use a calibrated scale to weigh animals less than three months and those at or above breeding age.

 The study results were reported in the October Journal of Dairy Science.

This table compares the bodyweight measurements of Holstein heifers of various ages using three methods.

                                     Number of animals                             Bodyweight     (pounds)

Age group                                                                    Electronic scale Hipometer        Heart-girth tape

Less than 3 months                 32                                163                             170                  128

3 to 5.9 months                         18                                289                              282                  284

6 to 8.9 months                         74                                452                              448                  439

9 to 11.9 months                      100                              587                              582                  576

12 to 14.9 months                     65                               756                              747                  747

15 to 17.9 months                     8                                1,067                           1,045               1,052

18 to 20.9 months                     5                                1,299                           1,200               1,222

21 months and older                9                               1,349                            1,303               1,319


Source: Adapted from the October 2006 Journal of Dairy Science, Vol. 89, p. 3992-3998.