Vitamin D enriched milk production from UV-B irradiated yeast supplementation in dairy cow diet

Abstract

The objectives of this study were to optimize methodology for producing UV-B irradiated vitamin D enrich yeast, measure vitamin D concentration of rumen fluid supplemented with UV-B irradiated vitamin D enrich yeast at incubation for 24 hours and optimize concentration of UV-B irradiated vitamin D enrich yeast in dairy cow diet. The study was divided into 2 parts including vitamin D enrich yeast production and vitamin D enrich milk production in dairy cows. For vitamin D enrich yeast production, Baker’s yeast strain was tested in YPD broth media by exposing them to different UV-B irradiations for 0, 2, 4, 8, 10, 12, 16 and 24 hours. This study found that UV-B irradiation of all treated yeast enhanced the amount of vitamin D2 and the maximum amount of vitamin D2 at 10 hours (8,409,277.11±9,336 vs. 70.5±7.3 IU/100g DM) was significantly different (P <0.05). For vitamin D production comparison of two yeast strains, Baker’s yeast and S. cerevisiae were treated at 0, 2, 4, 8, 10, 12, 16 and 24 hours in an UV-B irradiation chamber in YM broth media. The result showed that the UV-B irradiation of both yeast strains could significantly enhance vitamin D2 to the highest amount at 16 hours compared to yeast without UV-B irradiation (3,623,174.08±7,331 vs. 814.49±58 IU/100g DM, and 2,437,194.38±5,508 vs. 1,569.87±37 IU/100g DM, respectively). The Baker’s yeast specimens revealed significantly increased amounts of vitamin D2 that were higher than S. cerevisiae after 16 hours of UV-B irradiation (P < 0.05). The UV-B irradiated Baker’s yeast was determined in vitro nutrient digestibility and vitamin D degradation in the rumen. The corn stover and TMR were used as experimental diet for determination of in vitro nutrient digestibility and vitamin D degradation in the rumen, which included three treatments that involved each type of feed, namely feedstuffs without yeast supplementation (Control), feedstuffs with live yeast supplementation (Yeast), and feedstuffs with UV-B irradiated vitamin D enriched yeast supplementation (UV-B Yeast). Gas accumulation of the live yeast supplementation group and the UV-B irradiated vitamin D enriched yeast supplementation group at 12, 24, 48, 72, and 96 hours of incubation time, were significantly higher than those of the control groups for both types of feedstuffs (P<0.05). At 24 hours of incubation time, the amounts of acetic acid and propionic acid in the live yeast supplementation group and the UV-B irradiated vitamin D-enriched yeast supplementation group were significantly higher than those in the control groups for both types of feedstuffs (P<0.05). The vitamin D content losses of the vitamin D enriched yeast supplementation groups were significantly lower than those of the commercial vitamin D groups (P<0.05). For vitamin D enrich milk production was divided into 2 experiments. In the first experiment to evaluate the effects of UV-B irradiated enrich yeast on milk production performance in dairy farm condition, twenty-seven Holstein-Friesian cows (8.6±1.4 kg/day), and body weight (BW; 540.0±30.0 kg) were assigned and analyzed using completely randomized design (CRD). There were divided into 3 treatments (7 days of preliminary and 21 days of collection periods). All of the treatments were fed with TMR which each group fed with different feed additive, including (1) TMR without yeast supplementation (CON), (2) TMR with 1.6 g/day non UV-B irradiation yeast (Non UV-B IY), and (3) TMR with 1.6 g/day UV-B irradiated vitamin D enrich yeast (200,000 IU/day; UV- B IVDRY). Milk yield was recorded every day, milk and blood samples were collected on days 0, 7, 14 and 21 of collection periods for milk composition and blood metabolites analysis. This study found that milk fat in the UV-B IVDRY group at day 14 was significantly higher than on day 0 of the experimental period (5.67 vs. 4.52%; P<0.05). UV-B irradiated enrich yeast supplementation had no effect on blood chemistry profiles in dairy cows. In the second experiment to evaluate the effects of UV-B irradiated enrich yeast on milk production performance and vitamin D content in milk, six Thai Friesian cows in the second lactation were grouped according to milk production (11.2 ± 2.0 kg/day), and body weight (BW; 415.0 ± 20.0 kg), were used in a replicated 3 x 3 Latin square design, with three treatments and three periods. Each period had a 49-day duration, where the first 14 days of each period were for adaptation to the diets, and the last 35 days were for data and sample collection. They were randomly allocated to one of three treatments: (1) basal diet without yeast (CON), (2) basal diet with 5 g of live yeast (LY), and (3) basal diet with 5 g of UV-B irradiated vitamin D enriched yeast (VDY; 150,000 IU/head/day of vitamin D2). Milk production was recorded daily, milk sample collection occurred on days 14 and 35 of each collection period, and blood plasma was collected on days 0, 7, 14, 21, 28, and 35 of each collection period. At 14 and 35 days of the collection period, dairy cows from the LY and VDY groups had milk lactose levels significantly higher than the CON group (4.37, 4.38 vs. 4.28 %, and 4.33, 4.34 vs. 4.23 %, respectively), and the VDY group had significantly higher vitamin D content in milk than the LY and CON groups (376.41 vs. 305.15, 302.14 ng/L and 413.46 vs. 306.76, 301.12 ng/L, respectively). Furthermore, dairy cows fed the VDY group had significantly higher 25(OH)D2 status in blood than the CON and LY groups. In conclusion, UV-B irradiation can produce vitamin D enriched yeast. UV-B irradiated vitamin D enriched yeast improved the in vitro ruminal degradation, while also preventing a loss in the amount of vitamin D that was degraded by the rumen microorganisms, as well as UV-B irradiated vitamin D enriched yeast supplementation in dairy cow diets were able to enhance vitamin D2 content in milk without detrimental effects on the health status and overall milk production.