The effect of the source and level of dietary vitamin D in the sow's gestation diet and the creep on growth and bone metabolism of the offspring were studied by A-K. M. Witschi of the ETH in Zurish and co-authors there and in Aarau and Basel. Their paper is published in a recent issue of the Journal of Animal Science.

Piglets are born with reduced plasma concentrations of 25-hydroxycholecalciferol (25-OH-D₃) and are thus highly predisposed to vitamin D deficiency, explain the paper's authors. Furthermore, sow milk contains little vitamin D and the slow intestinal vitamin D absorption of sows limits the efficacy of dietary vitamin D supplementation. Hence, the neonatal piglet depends, to a large extent, on the vitamin D stores built up in foetal tissues from maternal sources.

The study was undertaken to evaluate whether the source and quantity of dietary vitamin D provided to the gestating and lactating sow, and also directly in the form of creep feed to the piglet, would influence the vitamin D status, growth performance and skeletal development of piglets.

A total of 39 primiparous and multiparous sows were randomly assigned to one of three dietary treatments (13 in each treatment), supplemented with either 5 or 50µg of the commonly used cholecalciferol (vitamin D₃) or 50µg of 25-OH-D₃ per kilogram of feed. By week 3 of lactation, piglets were offered a creep diet with vitamin D supplementation according to the treatment of the dam, and they were offered the same creep diets after weaning at day 35 of age until they reached a bodyweight of approximately 20kg.

When dietary 25-OH-D₃ was provided, circulating concentrations of 25-OH-D₃ in piglet serum increased (P<0.05) as early as day 21 and later at day 33 and 77, indicating greater body stores in those animals. Bone-breaking strength and cortical bone mineral content and density at the tibial mid-shaft of piglets were reduced (P<0.05) when vitamin D₃ was supplemented at 5µg/kg compared with the bone traits of other groups but no differences (P>0.05) were observed between the two other groups.

After weaning, average daily feed intake (ADFI) was greater (P<0.05) and growth performance tended (P=0.08) to improve when doses of 50µg/kg were administered, regardless of the vitamin D source.

Witschi and co-authors concluded that supplementation of the diet with 50µg/kg of either source of vitamin D was adequate to meet the needs of gestating sows and in permitting the accumulation of vitamin D in foetal tissues, as well as for normal skeletal mineralisation and growth in the offspring.

Furthermore, they said, the markedly improved vitamin D status of piglets whose mothers received 25-OH-D₃ possibly resulted from greater tissue reserves present at birth and a greater availability of vitamin D when released from those stores.

Reference

Witschi, A-K. M., A. Liesegang, S. Gebert, G. M. Weber and C. Wenk. 2011. Effect of source and quantity of dietary vitamin D in maternal and creep diets on bone metabolism and growth in piglets. J. Anim. Sci., 89 (6): 1844-1852.

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