Difference in the Levels of Vitamin C Between High Versus Low Producing Dairy Cows
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Difference in the levels of Vitamin C between high versus low Producing Dairy Cows
By: Alecia P. Knapp, Advisor - J.H. Hampton
University of Wisconsin-Platteville Animal Science Department
Abstract
We hypothesize that high-producing dairy cows will have lower Vitamin C concentrations versus low-producing dairy cows due to their bodies’ higher demand for glucose. Lactating Holstein cows (n=40) were randomly selected from the University of Wisconsin Platteville milking herd and assigned to either high production (HP; n=20) or low-production (LP; n=20) group based on DHI predicted 305-day milk yields (Ag Cooperative Services). Cows in the HP group had predicted 305-day milk yields ≥27,000 lbs. of milk while cows in the LP group had predicted 305-day milk yields <26,999 lbs. of milk. Neither number of days in milk (DIM) or lactation number were significant between groups (P =.3041; P=.1983). Serum samples were used to measure Vitamin C concentrations using the Cayman Chemical Ascorbate Assay kit. The average Vitamin C concentration for the HP group was 17.871.03 and the LP group was 31.831.03 (P <0.0001). Results support previous studies, which showed that lactating cows may not have enough dietary glucose to produce milk and also produce enough Vitamin C (MacLeod, 1999). Further studies are necessary to determine if supplementation of glucose increases Vitamin C concentrations in high producing dairy cows.
Introduction
Vitamin C (C6H8O6) is a water soluble vitamin with antioxidant properties. Some species, such as humans, cannot manufacture their own, while others, including ruminants, can perform biosynthesis of vitamin C. Vitamin C biosynthesis in ruminants occurs in the liver and process glucose. Because ruminants are able to produce their own vitamin C a dietary requirement has yet to be determined. It is important that ruminants produce their own vitamin C as the bacteria in the rumen break down a high majority of any dietary supplements of the vitamin.
Glucose is a precursor to both vitamin C and milk, so it is in high demand in the body of a lactating dairy cow. Studies have shown that when a high producing dairy cow is lactating, her body allocates glucose to milk production over that of Vitamin C, which can lead to a shortage of Vitamin C.
A lactating dairy cow’s body is under a high level of stress, and antioxidants, such as vitamin C, help to manage that stress level. When there is a shortage of vitamin C this reduces the body’s ability to handle the stress from lactating, which can be measured via cortisol concentrations. Cortisol is a glucocorticoid produced by the bovine adrenal gland and is released in response to chronic stress. Cortisol increases coincident with peak lactation (40-60 days post-calving) in dairy cows (Sartin et al., 1988) indicating that during this time period cattle are under greater stress. Previous studies have indicated that Vitamin C, an antioxidant, has the ability to inhibit cortisol production (Montalvo et al., 2001). Thus, the effect of reduced vitamin C is amplified in high-producing versus low-producing dairy cows, since high producing dairy cows have higher blood concentrations of cortisol (Sartin et al., 1988).
We hypothesize that high-producing dairy cows will have lower Vitamin C concentrations versus low-producing dairy cows due to their bodies’ higher demand for glucose.
Materials and Methods
All procedures were approved by the University of Wisconsin-Platteville Animal Care and Use Committee. Lactating Holstein cows (n=40) were randomly selected from the University of Wisconsin Platteville milking herd and assigned to either high production (HP; n=20) or low-production (LP; n=20) group based on DHI predicted 305-day milk yields (Ag Cooperative Services). Cows in the HP group had predicted 305-day milk yields ≥27,000 lbs. of milk while cows in the LP group had predicted 305-day milk yields <26,999 lbs. of milk. Number of days in milk (DIM) ranged from 10-230, and lactation number ranged from 1st to 4th lactation. All cattle were housed at the University of Wisconsin-Platteville Dairy Center in 2 adjacent free-stall pens and were provided a balanced TMR, free choice mineral mix, and water.
Blood was collected from the coccygeal vein at the underside of the base of the tail. All samples were collected after morning milking, on the same day within four hours of each other. SST 8.5 mL BD Vacutainers with clot activator were used. After collection the blood was allowed to clot for approximately 30 minutes and then placed on ice. Samples were then centrifuged within two hours of collection for 30 minutes at 1800 G. Serum was then separated and put into deep well plates. Protocol was then followed to the point of sample storage for the Cayman Chemical Ascorbate Assay kit. Samples were then stored at -80◦ C until they were shipped to the Pennington Biomedical Research Center in Baton Rouge, Louisiana for the completion of the assay.
Results
All statistical measures were performed using SAS. Average DIM = 102 7 days, and was not significantly different between groups (P=0.3041). Average lactation number = 2.10.2, and was not significantly different between groups (P=0.1983). Predicted 305-day milk averages were 31,887± 606.23 lbs. of milk (HP) and 23,155±606.23 lbs. of milk (LP) and were significantly different (P <0.0001). Vitamin C concentration averages were significantly lower in the HP group (17.87±1.03) than the LP group (31.83±1.03) with P<0.0001 (Figure 1).
Figure 1: Serum Vitamin C levels in Lactating Dairy Cows with. High Production Mean =17.87 ±1.03. Low Production Mean = 31.83 ±1.03 (P <0.0001)
Discussion
Our results support the hypothesis that high producing dairy cows have a lower vitamin C due to reduced glucose availability. When both high and low producing dairy cows are feed the same ration, the lower producing cows will use less of the glucose gained from their diet for milk, leaving more left over for vitamin C production and other biological processes. Further research will need to be done comparing cortisol levels in high and low producing dairy cows to see if there is a correlation with the vitamin C levels. Also, research can be done looking at glucose supplementation and vitamin C levels in lactating dairy cows.
References
MacLeod, D. D., X. Zhang, L. Ozimeck and J. J. Kennelly.Ascorbyl-2-polyphosphate as a source of ascorbic acid for dairy cattle.Milchwissenschaft. 1999. V54:123-129.
Montalvo, CP, NH Díaz, LA Galdames, ME Andrés, and RE Larraín. Short communication: effect ofvitamins Eand C on cortisol production by bovine adrenocortical cells in vitro. Journal of DairyScience. 2011. V 94(7):3495-7
Sartin, JL, RJ Kemppainen, KA Cummins, and JC Williams.Plasma Concentrations of Metabolic Hormones in High and Low Producing Dairy Cows.Journal of Dairy Science. 1988. V71 (3):650-657