The benefits of vitamin D are not only evident in humans. Scientists are discovering the importance of adequate Vitamin D levels in breeding animals as well. The SowBridge Breeding Herd Education Studies Program recently featured M.D. Lindemann and Y.D. Jang, both with the University of Kentucky Department of Animal and Food Sciences, who discussed the vitamin D needs of sows.
About Vitamin D
As one of the four fat-soluble vitamins, vitamin D is intimately involved in calcium and phosphorus utilization (Ca-P homeostasis and bone mineralization). In the human area, there has been renewed interest in vitamin D from the aspect of immune regulation. Known as the “sunshine vitamin,” it can be obtained from the body itself or can come from feedstuffs in the diet. Sunlight turns vitamin D into cholecalciferol.
“We supplement with vitamin D3 because some animals don’t utilize vitamin D2 as efficiently,” says Lindemann. He explains that when vitamin D is made in the body, two things have to happen.
A hydroxal group has to be added on to deliver the vitamin and the kidneys add on a hydroxal group.
Metabolites for vitamin D include:
- 7-dehydrocholesterol: Converted to cholecalciferol (vitamin D3) in skin under ultraviolet irradiation
- Cholecalciferol: Found in animals (called ergocalciferol in plants)
- 25-hydroxyvitamin D (25-OH D): Hydroxylated in liver
- 1, 25-dihydroxyvitamin D: Hydroxylated in kidney
- 24, 25-dihydroxyvitamin D: In the breakdown pathway
Hydroxylated vitamin D metabolites are distributed in pig plasma and tissues (including the liver, kidney and adipose tissue).
- 1,25-(OH)2D3 is the active compound found in the tissue more than in plasma (stored or active form)
- 25-OH D3 is much higher in the plasma than in the tissue, and is the best indicator for measuring Vitamin D because it has 20 to 30 days of plasma half-life. “This is what’s reported back to producers,” says Lindemann.
- 25-OH D2 has a lower concentration in animal tissues
- Vitamin D3 has five to seven days of plasma half-life
- 1,25-(OH)2D3 has four to eight hours of plasma half-life
More Incidence of Bone Disease
Lindemann reports increased cases of metabolic bone disease in swine, hence the impetus to further research vitamin D. Since more animals are raised in environmentally controlled conditions, he suggests the reason could be due to pigs receiving less sunshine than they once did. Horst and Littledike researched low vitamin D at birth (1982).
“The Veterinary Diagnostic Lab at Iowa State University has seen more incidents of bone disorders,” says Lindemann. “And if it’s a bone issue, it’s related to calcium and phosphorus. Work was published back in the 1980s in Iowa that shows lower levels in pigs at birth than in other species. And since this is the sunshine vitamin, if we block access to sunlight, are we compromising pigs’ vitamin D status.”
Vitamin D deficiency results in severe bone disease, including:
- Rickets: A failure in adequate bone mineralization
- Osteomalacia: A demineralization of formed bone
- Osteoporosis: A diminished bone mineral content and mass
Research by Jesse Goff et al. (1984) showed that intramuscular injection of vitamin D3 to sows at 20 days pre-partum resulted in the enhancement of its status in sows. Lindemann says that vitamin D status of sows is closely correlated to that of neonatal piglets.
“The improvement of maternal vitamin D status could be effective to enhance status of offspring if needed,” he says. “Goff’s research shows a clear relationship between vitamin D levels in the sow plasma and levels in the piglet plasma. Levels in the blood ranged from 40 on the low end to 200 on the high end (see chart). If we can change the sow status, we can change the piglet status."
Consider the comparison of two experiments in the accompanying chart to the right.
Experiment 1 results show vitamin D levels can be increased either by injection or by diet. Vitamin D levels at birth are similar between the two studies, and both studies indicate vitamin D levels can increase in the piglet blood by means of either injection or diet. In addition:
- 25-OH D3 concentrations in plasma of gilts and sows were linearly increased by increasing the level of vitamin D3
- 25-OH D3 supplementation was more efficient than vitamin D3 to increase its plasma status
“The 25 hydroxy is clearly higher than in the control animals,” says Lindemann. “We see increases in vitamin D levels in these gilts. We also see a significant reduction in the number of stillborn pigs.”
By 14 days after challenge, we have a significant response in the pigs that were given Vit. D. When you put a challenge into the system, you get a higher response.”
Based on available research, Lindemann says vitamin D3 supplementation to sows in gestation (either through dietary supplementation or injection) can improve 25-OH D3 status for both sows and their progeny. In addition, vitamin D3 administration to piglets can improve its serum status regardless of administration routes.
“Using an injection method is more efficient to enhance vitamin status than oral or dietary administrations,” says Lindemann. “The injectible route had the numerical highest serum 25-OH D3 concentrations compared to the oral route.”
Additionally, the researcher states vitamin D administration has the potential to boost immune response under disease-challenge conditions.