Impact of blood plasma calcium on lifetime performance

First published in International Dairy Topics Volume 18.4.

The plasma calcium level around parturition has been shown to have a major effect on fertility. The economic impact of improving the calcium level at calving – obtained by supplementing the pre-partum animals with the product X-Zelit, as reported by Kerwin et al. (2018, 2019) – was simulated using the Simherd model.

Reproduction and yield

Supplementing X-Zelit (Vilofoss) in the late part of the dry period is known to increase fertility (Fig. 1) and milk yield (Fig. 2). Fig. 1 shows the proportion of cows not pregnant. Median time to pregnancy was 19 days earlier for cows fed X-Zelit.
This highly improved reproduction result corresponds to a study in New Zealand in which pasture-fed multiparous cows were supplemented with X-Zelit. The cows which were given X-Zelit became pregnant 7.5 days earlier in lactation compared to the control group. In this study, pregnancy was also assessed in relation to when seasonal insemination begins, and it was found that cows in the X-Zelit group became pregnant 13.8 days earlier in the season compared to the control group.
Also, in a trial conducted by Martinez et al. (2012), the normocalcaemic group had 15 fewer empty days compared to the hypocalcaemic group. In the same trial, the probability of a positive pregnancy in normocalcaemic cows was estimated to be 1.61 times higher than the probability in hypocalcaemic cows.

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Over the last year we have been taking a good look at our dry cow processes to improve health and fertility. As part of this we spoke to a number of farmers with herd sizes ranging from 90 through to 2000 cows and they all recommended using X-Zelit pre-calving. So, we tried X-Zelit in a dry cow nut and we were really impressed with it. Since using it, we’ve had very few issues with our calving cows, they are calving really easily and cleanly. I’m not too sure why it works but it just does, it’s a great product!