Effects of increasing calcium propionate in a finishing diet on dry matter intake and glucose metabolism in steers

Abstract

The objective of this study was to determine whether increasing propionate alters dry matter intake (DMI), glucose clearance rate, blood metabolites, insulin concentrations, and hepatic gene expression in steers fed a finishing diet. Holstein steers (n = 15; BW = 243 ± 3.6 kg) were individually fed a finishing diet ad libitum. Steers were allocated by body weight (BW) to receive: no Ca propionate (Control), 100 g/d Ca propionate (Low), or 300 g/d Ca propionate (High) in the diet. Orts were collected and weighed daily to determine DMI. Blood samples were collected on days 0, 7, and 21, and BW recorded on days 0, 14, and 28. An intravenous glucose tolerance test (IVGTT) was conducted on days 14 and 28 of the trial. Liver biopsies were collected on day 33 for gene expression analysis. Blood samples were analyzed for whole blood glucose and lactate, plasma non-esterified fatty acids (NEFAs), and insulin concentrations. Data were analyzed using a mixed model with treatment, day and their interaction included, with day and minute as a repeated measure. The control treatment had greater (P < 0.01) DMI than low and high steers. Body weight was increased in control steers on days 14 and 28 compared with the steers receiving the High treatment (P = 0.03 for the interaction). Blood glucose concentrations tended (P = 0.09) to be higher on day 21 than days 0 and 7 but was not affected by treatment (P = 0.58). Plasma NEFA concentrations were lower (P = 0.05) for control steers than other treatments, and greater (P = 0.002) on day 0 than days 7 and 21. Blood lactate concentrations were greater (P = 0.05) on day 7, than days 0 and 21, but not affected by treatment (P = 0.13). High steers had greater plasma insulin concentrations in response to the IVGTT than steers on the other treatments (P = 0.001). There was no treatment (P ≥ 0.16) or day effect (P ≥ 0.36) on glucose peak, plateau, or clearance rate. High steers had greater expression of solute carrier family 16 member 1 (SLC16A1; P = 0.05) and tended to have greater hepatic expression of solute carrier family 2 member 2 (SLC2A2; P = 0.07). These data indicate that increased propionate may decrease DMI and insulin sensitivity.

Keywords: cattle; finishing diet; glucose metabolism; intravenous glucose tolerance test; propionate.

Figure 1.

The interaction of treatment and day on steer dry matter intake (DMI; P = 0.24). Steers were fed a finishing diet that was top dressed with calcium propionate at 0 g/d (control, ● ), 100 g/d (low, ● ), or 300 g/d (high, ● ). P-values for the main effects of both treatment and day for DMI were <0.001. DMI was greater for control steers from days 0 to 35 compared with both low and high steers. DMI was not included for days 13 and 27 as steers were fasted for the 12 prior to intravenous glucose tolerance tests on days 14 and 28.

Figure 2.

The interaction of treatment and day on steer body weight (BW; P = 0.027). Steers were fed a finishing diet that was top dressed with calcium propionate at 0 g/d (control, ● ), 100 g/d (low, ● ), or 300 g/d (high, ● ). P-values for the main effects of treatment and day for BW were 0.25 and <0.001, respectively. Body weight was greater for control steers from days 0 to 28 compared with both low and high steers.

Figure 3.

The interaction of treatment and minute on steer blood glucose during intravenous glucose tolerance tests (P = 0.020). Steers were fed a finishing diet that was top dressed with calcium propionate at 0 g/d (control, ● ), 100 g/d (low, ● ), or 300 g/d (high, ● ). Intravenous glucose tolerance tests were conducted on days 14 and 28 following a 12 h fast. P-values for the main effects of treatment and minute for blood glucose were 0.11 and <0.001, respectively.

Figure 4.

The interaction of treatment and minute on steer plasma insulin during intravenous glucose tolerance tests (P = 0.001). Steers were fed a finishing diet that was top dressed with calcium propionate at 0 g/d (control, ● ), 100 g/d (low, ● ), or 300 g/d (high, ● ). Intravenous glucose tolerance tests were conducted on days 14 and 28 following a 12 h fast. P-values for the main effects of treatment and minute for plasma insulin were 0.20 and <0.001, respectively..