In addition to the well-studied effects in regulating calcium and phosphorus balance, vitamin D has many non-calcemic effects that include acting as an immune modulator or an antioxidant. Cows acquire vitamin D either from photosynthesis in the skin or through swallowing fungi in the forage or vitamin D supplements. Although vitamin D deficiency is rare, today we are facing an increasing number of vitamin D deficiencies in cows due to the indoor housing away from sunlight exposure. According to the NRC recommendation, to maintain the vitamin D serum concentration in the range of 20 to 50 ng/ ml, it is necessary to administer 21,000 IU/ d of vitamin D in cattle. In addition, considering the involvement of vitamin D in various calcemic and non-calcemic effects, it seems that previously recommend levels of vitamin D supplementation have not been enough for preventing many diseases and disorders in cattle. Vitamin D toxicity may also occur due to over-supplementation of vitamin D or overgrazing in plants with high amounts of vitamin D metabolites. This review article will discuss various roles of vitamin D in dairy cattle health, normal physiology, and disease prevention.

Vitamins play an important role in improving the performance, immune system, and growth of birds. In recent years, due to the increase of the price of synthetic vitamin supplements and also due to the limitation of the use of commercial antioxidants, plant-based antioxidant sources have been considered in the poultry industry. Therefore, this study aimed to investigate the effects of herbal vitamin E supplements on production traits, humoral immune responses, and some blood parameters of broiler chickens.

In a completely randomized design 480 Arian broiler chickens (one-day-old, mixed sexes) were allocated to four treatments, four replicates, and 30 birds in each replicate. Experimental treatments included: 1. basal diet (Contains 25 IU of synthetic vitamin E), 2. basal diet + 25 IU synthetic vitamin E, 3. basal diet + 50 mg herbal vitamin E supplement, and 4. basal diet + 100 mg herbal vitamin E Supplement. In this experiment, weight gain, feed intake, and feed conversion ratio (FCR) were measured. On day 40, two birds per replicate were randomly selected, weighed, and killed, and then the entire empty carcass and parts of the carcass including breast, thigh, neck back, and wings, abdominal fat, and some organs including heart and spleen were weighed. One day 40 days, to measure the concentration of total protein, albumin, triglyceride, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and the activity of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase enzymes, blood was collected from each replicate of 4 birds. On day 33 to measure antibody titer against Newcastle disease and influenza, 1 ml SRBC was injected into 4 birds in each repetition.

  The results showed that the experimental treatments had no effects on feed intake, body weight, and FCR. Also, carcass characteristics including carcass percentage, breast, thigh, back, and neck percentage, abdominal fat, heart, spleen, and blood parameters were not affected by experimental treatments. Antibody titer against sheep red blood cell injection had no significant effect.

In total, according to the recommendation of commercial strains, the requirement of vitamin E is 50 IU, therefore in case of providing 25 IU of synthetic vitamin E in the diet, it is possible to provide the rest of the need up to 50 IU by using the herbal vitamin E supplement (at the rate of 50 mg per kilogram of feed) considering there are economic considerations.