Effect of feeding 25-hydroxyvitamin D3 with a negative cation-anion difference diet on calcium and vitamin D status of periparturient cows and their calves

Abstract

Holstein cows (>1 gestation) were fed 1 of 3 diets during the last 13 d of gestation (ranged from 22 to 7 d). The control diet (16 cows) was formulated to provide 18,000 IU/d of vitamin D3 and had a dietary cation-anion difference (DCAD) of 165mEq/kg (DCAD=Na + K - Cl - S). The second diet (DCAD + D) provided the same amount of vitamin D3 but had a DCAD of -139mEq/kg (17 cows). The third diet (DCAD + 25D) had no supplemental vitamin D3 but provided 6mg/d of 25-(OH) vitamin D3 [25-(OH)D3] with a DCAD of -138mEq/kg (20 cows). Diets were fed until parturition and then all cows were fed a common lactation diet that contained vitamin D3. Negative DCAD diets reduced urine pH, with the greatest decrease occurring with the DCAD + D treatment. Urinary Ca excretion was greatest for cows fed DCAD + 25D followed by cows fed DCAD + D. Urinary pH was negatively correlated with urinary excretion of Ca for cows fed DCAD + D. No such correlation was observed with the DCAD + 25D treatment because substantial excretion of urinary Ca occurred at moderate urinary pH values for that treatment. Cows fed DCAD + 25D had greater serum concentrations of 25-(OH)D3 than other treatments from 5 d after supplementation started through 7 d in milk. Concentrations of 1,25-(OH)2D3 in serum were greatest in DCAD + 25D cows starting at 2 d before calving and continued through 7 d in milk. Serum Ca concentrations 5 d before calving were greatest for cows fed DCAD + 25D, but at other time points before and after parturition treatment did not affect serum Ca. Incidence of clinical hypocalcemia was not statistically different between treatments, but cows fed DCAD + 25 had the highest incidence rate (12.5, 0, and 20% for control, DCAD + D, and DCAD + 25D). Calves born from cows fed DCAD + 25D had greater concentrations of 25-(OH)D3 in serum at birth than calves from other treatments (before colostrum consumption), but concentrations were similar by 3 d of age. Concentrations of 25-(OH)D3 in colostrum and transition milk were increased by feeding DCAD + 25D, but by 28 d in milk treatment effects no longer existed. Overall, feeding 25-OH vitamin D with a negative DCAD diet increased vitamin D status of the cow and her newborn calf but had minimal effects on calcium status and did not have positive effects on the incidence of hypocalcemia.

Effects of prepartum dietary cation-anion difference on aspects of peripartum mineral and energy metabolism and performance of multiparous Holstein cows

“…Another mechanism of action for low DCAD diets in preventing hypocalcemia in the transition period is through increases in urinary Ca excretion prepartum. Decreasing DCAD consistently increases urinary Ca excretion to some degree (Gaynor et al, 1989;Joyce et al, 1997;Goff et al, 2014), and the magnitude of increase is highly correlated with urine pH (Grünberg et al, 2011;Weiss et al, 2015). A potential mechanism for this effect on urine Ca flux is a direct inhibition of Ca reabsorption from the filtrate in the kidney due to the additional acid load (Stacy and Wilson, 1970), which is supported by the strong linear relationship observed between urine pH and urine Ca-to-creatinine ratio in the current trial as well as in a previous study (Grünberg et al, 2011).…”

“…Early work on low DCAD feeding consistently showed decreased DMI during the prepartum period for negative DCAD rations, as summarized in the metaanalysis by Charbonneau et al (2006). More recently, the combination of minimizing basal dietary cations to reduce the amount of supplemental anions that need to be included in the ration, as well as the adoption of more palatable commercial anion sources, has resulted in several trials in which anions were supplemented to reach urine pH values close to the range of the current trial with no effect on prepartum intake (Moore et al, 2000;DeGroot et al, 2010;Weich et al, 2013;Weiss et al, 2015) or minimal effects that did not result in evidence of impaired metabolic health (Ramos-Nieves et al, 2009). The quadratic effect on prepartum intake in our trial suggested that cows fed MED had the highest intake in the prepartum period, with the lowest intake in cows fed LOW; however, absolute differences between groups were relatively small and we found no effects of treatment on peripartum plasma concentrations of glucose, NEFA, or BHB.…”

“…However, the critical threshold for acid-base balance at which PTH sensitivity is restored has not been identified. Increased urine Ca flux has been shown to become more pronounced as urine pH decreases (Grünberg et al, 2011;Weiss et al, 2015). Together, this indicates that more significant alterations in acid-base balance may have greater potential effects on Ca metabolism.…”

“…A meta-analysis by Charbonneau et al (2006) suggested that reducing DCAD resulted in linearly decreased prepartum DMI, discouraging lower DCAD feeding strategies. Since the publication of that metaanalysis, several studies have reduced urine pH to less than 6.5 without negatively affecting DMI (Moore et al, 2000;DeGroot et al, 2010;Weich et al, 2013;Weiss et al, 2015). Charbonneau et al (2006) also described a curvilinear relationship between DCAD and urine pH, suggesting that some threshold in DCAD must be reached before significant alterations in acid-base balance occur.…”

A Dairy Herd Case Investigation with Very Low Dietary Cation–Anion Difference in Prepartum Dairy Cows

“…Due to the use of these strategies, the prepartum cows should develop a mild metabolic acidosis. As a result, the activity of PTH will be enhanced, with an expected response of less hypocalcemia around parturition (2, 15). …”