Liver phosphorus content in Holstein-Friesian cows during the transition period

Abstract

Hepatic lipidosis and hypophosphatemia are frequently observed in high-yielding periparturient dairy cows. Objectives of this study were to investigate the association of the liver P content with the degree of liver fat accumulation and serum P concentration and to characterize the change in liver P content throughout the transition period. In a cross-sectional study, liver biopsies obtained from 33 Holstein-Friesian cows 14 d postpartum (p.p.) were assayed for total lipid (TLip), triacylglycerol, DNA, P, Mg, K, Na, and Ca content. Serum samples obtained at the time of biopsy were analyzed for indices of liver function and injury and the serum P concentration was determined. From this cross-sectional study, 6 cows were selected for a longitudinal study and liver tissue obtained from the 6 cows on d -65, -30, -14, 1, 14, 28, and 49 relative to calving was assayed. The amounts of P, K, Mg, Na, and Ca were expressed as amount in dry weight (DW), wet weight (WW), nonfat wet weight (NFWW), and indexed to DNA. In the cross-sectional study, P(DW) and P(WW) decreased with increasing TLip, whereas P(NFWW) and P(DNA) were independent of TLip. Values for P(DNA) varied widely, whereas P(NFWW) varied within a narrow range. Stepwise regression analysis revealed the strongest associations between P(DW) and the amount of tissue water (partial R2 = 0.74) and the log to the base 10 of triacylglycerol (partial R2 = 0.05). The P(WW) was associated with the log to the base 10 of triacylglycerol (partial R2 = 0.20), but no associations were found for P(NFWW). These findings indicate that decreased electrolyte content in dry and wet liver tissue with increased liver lipid content is predominantly due to the decrease in tissue water and therefore the distribution volume of electrolytes. In the longitudinal study, P(DW), P(WW), and P(NFWW) were decreased on d 14 p.p. Similar directional decreases were found for K, Mg, and Na, but P was the only electrolyte that was significantly decreased in liver tissue at d 14 p.p. This finding indicates that the P content of liver tissue decreases in early lactation due to a reduction in hepatocellular cytosol volume as well as a decrease in cytosolic P concentration, with the latter having biological relevance. The clinical significance of decreased cytosolic P concentration in the hepatocytes of dairy cows in early lactation remains to be determined.

Serum Amyloid A and Haptoglobin Concentrations and Liver Fat Percentage in Lactating Dairy Cows with Abomasal Displacement

“…Our finding that [albumin] was not decreased in cattle with abomasal displacement suggests that albumin is not as sensitive an acute phase reactant as is SAA. Moreover, [albumin] is decreased for 2 weeks after calving in lactating dairy cattle, partly as a result of increased plasma volume and decreased albumin synthesis, 41,42 further decreasing the clinical utility of [albumin] as an acute phase reactant in postparturient cattle.…”

Effect of butaphosphan and cyanocobalamin on postpartum metabolism and milk production in dairy cows

“…In dairy cattle, the phosphorus content of liver tissue is decreased in early lactation (Grunberg et al, 2009). Phosphorus plays an important role in hepatic carbohydrate metabolism, as several intermediates in the gluconeogenic pathway must be phosphorylated.…”

Effect of multiple intravenous injections of butaphosphan and cyanocobalamin on the metabolism of periparturient dairy cows

“…Increased milk and milk protein yields have been observed following intramuscular cyanocobalamin administration (10 mg/cow per week) and oral cyanocobalamin supplementation (500 mg/cow per day; Girard and Matte, 2005;Graulet et al, 2007), but the effects on metabolism have been variable (Schuh, 1994;Fürll et al, 2006;Lohr et al, 2006). In dairy cattle, the phosphorus content of liver tissue decreases in early lactation due to a reduction in hepatocellular cytosol volume as well as a decrease in cytosolic phosphorus concentration (Grünberg et al, 2009). Phosphorus supplementation may therefore be indicated in periparturient dairy cows because phosphorus plays an important role in hepatic carbohydrate metabolism, in which all intermediates in the gluconeogenic pathway must be phosphorylated, and because the rates of gluconeogenesis and glycolysis are regulated by phosphorus availability (Berg et al, 2006).…”