Vitamin and mineral supplementation and rate of gain in beef heifers: Effects on concentration of trace minerals in maternal and fetal liver at day 83 of gestation

The objective of this study was to evaluate the effects of feeding vitamin and mineral (VTM) supplement and two different rates of gain during the first 83 days of pregnancy on trace mineral concentrations in maternal and fetal liver. Thirty-five crossbred Angus heifers (initial body weight [BW] = 792.6 ± 15.7 pounds [lb.]) were assigned randomly to one of four treatments in a 2 × 2 factorial arrangement with main effects of vitamin and mineral supplement (VTM or NoVTM) and rate of gain (GAIN; low gain [LG], 0.62 pounds per day [lb./d], vs. moderate gain [MG], 1.74 lb./d). The VTM treatment (113 grams [g]/ heifer/day) was initiated at least 71 days before artificial insemination (AI). At breeding, heifers were maintained on their respective diets (target gain of 0.62 lb./d) or fed a starch-based protein/energy supplement (target gain of 1.74 lb./d). Heifers were ovariohysterectomized on day 83 of gestation and samples of maternal and fetal liver were collected. Samples then were analyzed for concentrations of Se, Mn, Cu, Co, molybdenum (Mo) and zinc (Zn). In maternal liver, a VTM × GAIN was observed for Se (P = 0.02) and Mn (P = 0.03); Se concentrations were greater for VTM-LG than all other treatments, while Mn concentrations were greater for VTM-MG than VTM-LG heifers. Further, maternal liver from VTM had increased concentrations of Cu (P < 0.01) and Co (P = 0.04), whereas GAIN affected concentrations of Mo, with greater concentrations (P ≤ 0.02) in MG heifers. Greater concentrations of Se (P < 0.01), Cu (P = 0.01), Mn (P = 0.04) and Co (P = 0.01) were observed in fetal liver from VTM than NoVTM, while Mo (P ≤ 0.04) and Co (P < 0.01) in fetal liver were greater in LG than MG. In conclusion, concentrations of Se, Cu, Mn and Co were greater in fetal liver from VTM dams, while greater concentrations of Mo were observed in the liver of fetuses from LG dams. Concentrations of Zn were not affected by any of the nutritional strategies evaluated. These data provide insights into how nutritional management of beef heifers affect fetal liver stores of trace minerals, which may be beneficial for offspring health and productive performance.

The first trimester of gestation is a critical period for fetal development, when the placenta and all vital organs are developed. Many producers don’t realize that at that stage, not only the dam, but also the fetus, require proper trace mineral nutrition.

However, several biological processes, such as carbohydrate, protein and lipid metabolism, hormone and DNA synthesis are dependent on trace minerals (Van Emon et al., 2020). Further, the fetus is completely dependent on the dam for trace mineral supply; thus, an inadequate maternal trace mineral consumption can compromise reproduction and negatively affect embryonic and fetal development (Hostetler et al., 2003), which can have long-term consequences on offspring health and performance.

Therefore, developing studies evaluating how maternal nutritional strategies can affect the supply of trace minerals to the fetus is important. The current experiment characterized a research model we developed to evaluate the effect of managerial inputs on maternal and fetal trace mineral concentration. The primary aim of this study was to test the hypothesis that vitamin and mineral supplementation and rate of gain during the first trimester of gestation influences the concentrations of trace minerals in maternal and fetal liver.

All procedures were approved by the North Dakota State University Institutional Animal Care and Use Committee.

Thirty-five crossbred Angus heifers (initial BW = 792.6 ± 15.7 lb.) were assigned randomly to one of four treatments in a 2 × 2 factorial arrangement with main effects of vitamin and mineral supplementation (VTM or NoVTM) and rate of gain (GAIN; low gain [LG] 0.62 lb./d or moderate gain [MG] 1.74 lb./d). Briefly, the VTM supplement was initiated at least 71 days before artificial insemination.

At breeding, heifers were maintained on their respective diets (LG) or fed a starch-based protein/energy supplement (MG). This resulted in the following treatment combinations: 1) No vitamin and mineral supplement, low gain (NoVTM-LG; n = 9); 2) No vitamin and mineral supplement, moderate gain (NoVTM-MG; n = 9); 3) Vitamin and mineral supplement, low gain (VTM-LG; n = 9); 4) Vitamin and mineral supplement, moderate gain (VTM-MG; n = 8). Heifers were fed individually using Calan gates, and supplements were top dressed over the total mixed ratio (Table 1).

1 - Total Mixed Ration: Proportion of ingredients: prairie grass hay (55%), corn silage (38%) and dried distillers grains plus solubles (7%).
2 - NoVTM: No vitamin mineral supplement was a pelleted product fed at 0.99 lb./ heifer/day with no added vitamin and mineral supplement.
3 - VTM: Vitamin mineral supplement was a pelleted product fed at 0.99 lb./heifer/ day (consisting of 113 grams (g) of a vitamin and mineral supplement [Purina Wind & Rain Storm All-Season 7.5 Complete, Land O’Lakes Inc., Arden Hills, Minn.] and 337 g of a carrier).
4 - Starch-based protein/energy: An energy/protein supplement formulated with a blend of ground corn, dried distillers grains plus solubles, wheat midds, fish oil and urea; targeting gain of 1.74 lb./d for moderate gain and 0.62 lb./d for low-gain heifers.

Heifers were ovariohysterectomized on day 83 ± 0.27 of gestation. Liver biopsies were obtained from all heifers at surgery day. Following ovariohysterectomy, fetuses were harvested and dissected, and samples of fetal liver were collected. Samples were placed in 2 milliliter microtubes and snap frozen on dry ice and stored at minus 80 C for subsequent trace mineral analysis.

Concentrations of Se, Mn, Cu, Co, Mo and Zn were determined via inductively coupled plasma mass spectrometry at the Veterinary Diagnostic Laboratory at Michigan State University. Data were analyzed using the MIXED procedures of SAS for effects of VTM, GAIN and a VTM × rate of gain interaction. Differences were considered significant at a P- value ≤ 0.05.

In maternal liver (Table 2), a VTM × GAIN was observed for Se (P = 0.02) and Mn (P = 0.03); Se concentrations were greater for VTMLG than all other treatments, while Mn concentrations were greater for VTM-MG than VTM-LG heifers. Further, maternal liver from VTM had increased concentrations of Cu (P < 0.01) and Co (P = 0.04), whereas GAIN affected concentrations of Mo, with greater concentrations (P ≤ 0.02) in MG heifers.

1 - NoVTM: No vitamin and mineral supplement was a pelleted product fed at a 0.99 lb./heifer/day with no added vitamin and mineral supplement.
2 - VTM: Vitamin mineral supplement was a pelleted product fed at a 0.99 lb./heifer/day (consisting of 113 g of a mineral and vitamin supplement, formulated to deliver similar levels of vitamins and minerals that were fed pre-breeding, and 337 g of a carrier).
3 - Heifers fed a pelleted blend of ground corn, dried distillers grains plus solubles, wheat midds, fish oil and urea, targeting a gain of 1.74 lb./d.
4 - NoVTM-LG (n = 9); NoVTM-MG (n = 9); VTM-LG (n = 9); VTM-MG (n = 8).
ab - means without a common superscript differ (P ≤ 0.05).

In fetal liver (Table 3), greater concentrations of Se (P < 0.01), Cu (P = 0.01), Mn (P = 0.04) and Co (P = 0.01) were observed in fetal liver from VTM than NoVTM dams, while Mo (P ≤ 0.04) and Co (P < 0.01) concentrations were greater in fetal liver from LG than MG dams.

1 - NoVTM: No vitamin and mineral supplement was a pelleted product fed at 0.99 lb./heifer/day with no added vitamin and mineral supplement.
2 - VTM: Vitamin mineral supplement was a pelleted product fed at 0.99 lb./heifer/day (consisting of 113 g of a mineral and vitamin supplement, formulated to deliver similar levels of vitamins and minerals that were fed pre-breeding, and 337 g of a carrier).
3 - Heifers fed a pelleted blend of ground corn, dried distillers grains plus solubles, wheat midds, fish oil and urea, targeting a gain of 1.74 lb./d.
4 - NoVTM-LG (n = 9); NoVTM-MG (n = 9); VTM-LG (n = 9); VTM-MG (n = 8)

We would expect greater concentrations of all trace minerals in maternal and fetal liver in response to vitamin and mineral supplementation. However, that was not the case for two of the six trace minerals evaluated, Mo and Zn, whose concentrations were not affected by VTM supplementation.

Interestingly, heifers with moderate rates of gain had greater liver concentrations of Mo than LG heifers, but the opposite relationship was observed in fetal liver. We may speculate that the protein/energy supplement provided to MG heifers already was providing enough minerals to meet fetal requirements, therefore unsupplemented heifers (LG) had to mobilize more nutrients to the developing fetus to ensure an adequate supply and consequently liver storage.

Fetal liver stores of trace minerals are important for the neonate because bovine milk is poor in essential trace minerals (Abdelrahman and Kincaid, 1993). Additionally, an adequate trace mineral reserve is crucial in early life to maintaining health status (Van Emon et al., 2020).

In conclusion, concentrations of Se, Cu, Mn and Co were greater in fetal liver from VTM dams, while greater concentrations of Mo were observed in the liver of fetuses from LG dams. Concentrations of Zn were not affected by any of the nutritional strategies evaluated. These data provide insights into how nutritional management of beef heifers affect fetal liver stores of trace minerals, which may be beneficial for offspring health and productive performance.

The authors thank Purina Animal Nutrition LLC (Land O’Lakes Inc., Arden Hills, Minn.) and the North Dakota Agricultural Experiment Station for providing financial support for this research. The authors also thank the North Dakota State Board of Agricultural Research and Education Graduate Research Assistantship program for their support for this effort. Appreciation is expressed to personnel at the Central Grasslands Research Extension Center and the Animal Nutrition and Physiology Center for assistance with animal handling and feeding, and the NDSU Animal Science Nutrition Laboratory

Abdelrahman, M.M., and Kincaid, R.L. 1993. Deposition of copper, manganese, zinc, and selenium in bovine fetal tissue at different stages of gestation. J. Dairy. Sci. 76: 3588-3593. doi:10.3168/jds.S0022-0302(93)77698- 5.

Hostetler, C.E., R.L. Kincaid and M.A. Mirando. 2003. The role of essential trace elements in embryonic and fetal development in livestock. Vet. J. 166(2):125-139. doi:10.1016/S1090- 0233(02)00310-6.

Van Emon, M., C. Sanford and S. McCoski 2020. Impacts of Bovine Trace Mineral Supplementation on Maternal and Offspring Production and Health. Animals. 10(12): 2404. doi:10.3390/ani10122404.