Débora_Santschi_1
ArticleVolume Number July 15, 2019
Débora SantschiPh.D., Agr.

Can I use the « Valacta » tape to estimate heifer weight before weaning?

Le ruban « Valacta » fonctionne-t-il pour évaluer le poids des génisses en pré-sevrage?
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Although monitoring heifer growth sometimes falls last on the list of favorite things to do, it is an essential step to ensuring that our future producers get off to a good start. In fact, recent studies clearly demonstrate a link between pre-weaning weight gain and a heifer’s future performance; an increase of 100 g/day of average daily gain (ADG) can mean 150-200 kg more milk in the first lactation. Taking the time to evaluate ADG early in a calf’s life is therefore a wise and profitable investment. 

Is the « Valacta » tape accurate enough? That’s what Marwa Hasnaoui, master's student at Laval University1, set out to evaluate.

We weighed and measured hundreds of heifers…

A total of 250 Holstein heifers were weighed (scale) and measured (chest girth, height at withers, hip width and height) several times between birth and weaning2.  Out of all of the measurements taken, the chest girth was the one that showed the best correlation with the weight on the scale, and the least residual error.

Is the « Valacta » tape reliable for estimating weight ?

Next, Marwa evaluated the reliability of the Valacta tape at predicting the weight of young heifers. The equation behind this tape was established almost 20 years ago using measurements of Quebec heifers from birth to calving. The results demonstrate that the estimated weight is still very reliable overall for heifer weights between 30 and 160 kg taken for this study (see graph).

                     

What about ADG ?

If the tape is used to estimate ADG between two measurements, the ADG estimate shows a difference of around 30 g/d from the scale (ADG average of  0.92 vs. 0.95 kg/day for the scale and tape respectively).

Yes, the Valacta tape works !

Now that we have established that the tape can adequately evaluate the weight of pre-weaning calves, be sure to take the time to validate that the early days of your future producers are on track.

Objective : 100 kg at 2 months of age, followed by a gradual weaning. And remember, you can't improve what you don’t measure! If you would like a tape, ask your Lactanet technician or advisor.

1. Project under the supervision of Édith Charbonneau, Agr., funded by CRIBIQ-Novalait-CRSNG.

2. Three times a week, in the first three weeks of life, and then every two weeks up to 76 days old.

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