By Sigrid Beth Rasmussen, Junior Quality Manager, DanBred
Are you aware that the correct vitamin D status will allow gilts and sows to reach their optimal KPI’s in production, helping to maximise their genetic potential? Vitamin D is essential for the absorbtion of calcium and phosphorus, promoting healthy bone growth, helping to ensure correct conformation and longevity. Focusing on optimising the diets for gilts by the correct inclusion level of vitamin D will help to set a prime starting point for significant lifetime productivity.
Skeletal development and bone strength in gilts
Conformation is one of the important selection criterias when choosing gilts for future production, and a strong skeletal framework is essential in order to exploit the full genetic potential of a DanBred breeding animal. Good legs and a strong back will set a prime starting point for a long productive life.
Vitamin D is vital for skeletal development, as it has a direct effect on the dietary absorption of calcium (Ca) and phosphorus (P) – both key components in bone mineralization and bone strength. To obtain optimal bone strength and structure, the amount of vitamins and minerals supplied in the feed should always reflect the current nutritional recommendations.
Supplementing vitamins and minerals above recommendation is never advised. Overdosing dietary supplementation of vitamin D, Ca and P can lead to severe bone mineralization- causing rigid bones, decreased mobility, as well as a diminished ability to mobilize Ca and P. Therefore mineral overdosing is not only making the feed unnecessarily expensive, it will also impair the productivity and longevity of the animals.
Absorption of vitamin D
Vitamin D is one of four fat-soluble vitamins, essential for metabolism and the embedding of Ca and P into bone tissue. Naturally occurring vitamin D comes in two types- D2 and D3. In animals, the predominant form is D3 also known as cholecalciferol. Vitamin D is normally supplemented in feed, since raw materials usually contains a limited amount of naturally occuring D3.
Vitamin D supplied in feed is in general biologically inactive- meaning that it does not have an effect on the body in that state by itself. Upon absorption, the vitamin is hydroxylated (broken down by oxidation) within the body in several steps into the prehormone known as calcifediol or 25(OH)D3 and secondly into calcitriol or 1,25-(OH)2-D3. Calcitriol is often referred to as the biologically active form of vitamin D. It is the calcitriol which enhances the absorption of both Ca and P via the intestinal cells which are key factors in skeletal development and bone strength.
In addition to the Ca and P absorption, calcitriol also affects some immune functions that helps to reduce the effects of inflammation- another way in which vitamin D plays an important role in the development of healthy and strong gilts.
Reduce dosage if using a calcifediol additive
It has been shown that health and productivity can benefit from supplements of calcifediol additives, sometimes called HyD. Danish research has compared calcifediol to regular vitamin D3 and found that with identical concentrations in the feed, the blood content of calcifediol was twice as high when using calcifediol additives when compared to regular vitamin D3 additives (Burild, et al., 2016)
This knowledge can be transferred into a positive effect on sow productivity- particularly in weaning weight as the biologically active form of vitamin D is more easily transferred to the foetuses and sows’ milk than regular vitamin D3.
However, it seems that the positive effect is not directly transferable to growing pigs. A trial carried out by Maribo, Nielsen, & Jakobsen in 2007 concluded that with increasing supplements of calcifediol in growing pigs the bone strength was significantly diminished.
No trials have concluded on the long-term effect of high doses of calcifediol and calcium during the growth period. However, there are strong indications that reducing the dosage calcifediol compared to regular vitamin D3 can influence bone and leg strength in growing pigs including gilts.
Therefore when feeding growing pigs- especially gilts- it is imperative to adjust the added dose of calcifediol additives in the feed compared to regular vitamin D3 additives. (Tybirk, et al., 2018). Doing so will set a prime starting point on the road to release the genetic capability for optimum lifetime performance.
Take home message
Follow the nutritional recommendations on vitamin and mineral supply – avoid overdosing as this (aside from additional costs) can have unforeseen negative consequences on gilt Development.
If using a calcifediol additive for gilts, it is advised to reduce the dosage compared to regular vitamin D3 additives. This storage form of vitamin D is absorbed more efficiently, so a smaller dose is required to achieve the desired effect.
References
Bruun, T. S., & Tybirk, P. (2019). Pas på poltenes ben og led . Danish Pig Research Centre.
Burild, A., Lauridsen, C., Faqir, N., Sommer, H. M., & Jakobsen, J. (2016). Vitamin D3 and 25-hydroxyvitamin D3 in pork and their relationship to vitamin D status in pigs.
Maribo , H., Nielsen, D. H., & Jakobsen , J. (2007). Afprøvning af to D3-vitmaminkilder: 25-Hydroxy D3-vitamin som alternativ til den traditionelt anvendte D3-vitamin kilde . Danish Pig Research Centre .
Starkey, J. (2014). A role for vitamin D in skeletal muscle development and growth. Journal of Animal Science(92), s. 887-892.
Sørensen, G., & Nielsen, M. F. (2016). Hy-D in sow feed increases litter weight at weaning by 3.6 kg. Danish Pig Research Centre.
Tybirk, P., Sloth, N. M., Kjeldsen, N., & Shooter, L. (2018). Danish Nutrient Standards.
