A member of the Solanaceae family, Solanum glaucophyllum contains a compound with vitamin D activity.
Dr Kevin Stickney, a nutritionist at Harbro feed, said he was aware of Solanum glaucophyllum, having been introduced to it in 2011, and then having used the material in laying hen feeds during 2013 to 2014.
He told us: “With the complexity of the metabolic pathway of conventional vitamin D3 requiring both fully functional kidney and liver and there being a number of question marks about guaranteed optimal hepatic function, be that due to fatty infiltration or mycotoxin exposure, a form of highly active vitamin D would be beneficial to any livestock production that places sizeable demands on calcium and phosphorus homeostasis.”
Stickney said that either a rapidly growing skeleton or an out-pouring of calcium into egg shell represent extremes of trace element demands that are heavily reliant on vitamin D.
“Thus, the ability to “stretch” the legal maxima imposed on in-feed vitamin D at times of high demand, via the use of what amounts to the true hormonal form of vitamin D, whether in the growing replacement breeding pig, the fast-growing broiler/turkey, the replacement pullet or the hen in the latter stages of its egg producing lifetime, represents a valuable opportunity to protect the respective livestock producers production outcomes, with close focus on protecting animal welfare,” he added.
EFSA said the findings of the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) Panel on Solanum glaucophyllum is the risk assessor’s first evaluation carried out under the revised framework for feed materials covered by Regulation 767/2009.
The most potent form of Vitamin D3 is 1,25-dihydroxycholecalciferol (1,25(OH)2D3), which is the nutritionally active substance in Solanum glaucophyllum.
“Consequently, the assessment of Solanum glaucophyllum dried leaves when used in feed refers mainly to the safety and efficacy of 1,25(OH)2D3,” said the EU risk assessor.
However, ingestion of excessive amounts of Solanum glaucophyllum leaves can cause hypercalcaemia - elevated calcium levels in blood - and could be a health concern for animals.
In view of that, the European Commission asked EFSA to assess the safety of Solanum glaucophyllum standardized leaves (PAN) as a feed material, with a particular emphasis on the content of glycoside of 1,25(OH)2D3 in the ground leaves and the supply with and physiology of Vitamin D in the target species.
They concluded that glycosylation of the vitamin molecule affected biopotency in poultry and rats, but not in ruminants.
And the Panel said the species-related differences in biopotency of glycosylated 1,25(OH)2D3 prevented the setting of a universal vitamin D bioequivalence of PAN in terms of international units.
“Based on the limited number of endpoints, up to 1,000 mg PAN per kg of complete diet was considered safe for chickens for fattening and piglets, considering the short feeding time of these animal categories under practical conditions,” found the EFSA experts.
The Panel said PAN concentrations meeting the chicken’s requirement for vitamin D in diets without supplemental vitamin D3 could not be ascertained.
And they found no evidence for an improvement in zootechnical parameters when PAN was added to diets already supplemented with vitamin D3 in chickens, laying hens and piglets.
In dairy cows, they said its use can help in the prevention of milk fever, but a safe use level could not be set.
“Similarly, no common safe level can be set for all animal species,” found the Panel.
The full opinion can be read here.