TITLE:
Impact of Chromium Propionate Supplementation and Days of Adaptation on Energy Status in Newly Weaned Steer Calves*
AUTHORS:
Zachary Kidd Foster Smith
KEYWORDS:
Beef Steers, Chromium, Feedlot Adaptation, Insulin, Newly Weaned
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.13 No.4,
October
10,
2023
ABSTRACT: The objective of this research
was to evaluate the influences that supplemental dietary chromium propionate
(CrP; 0 or 0.4 mg·kg-1 added to the total diet on a DM basis) has on
plasma indicators of energy status in newly weaned steers upon introduction to
the feedlot. For this experiment single source, Angus steers (n = 28; BW = 289
± 12.0 kg) from a ranch in Western South Dakota were weaned and immediately
shipped 579 km to the Ruminant Nutrition Center (RNC) in Brookings, SD. Steers
were allotted to one of four 7.6 m × 7.6 m pens (2 pens/diet; 7 steers/pen) at
4 d post-arrival to the RNC and test diets were
initiated. No anabolic implant was used in this study. Subsequent BW measurements were obtained at 1400 h, to accommodate
a post-prandial timing for blood sampling. This was 4 h after initial
access to feed, and immediately prior to the afternoon feed delivery. Weights
and blood sampling occurred on d 5, 12, 19, and 33. Whole blood samples were
collected from all steers via jugular venipuncture and separated as plasma.
There were no diet x day interactions (P ≥ 0.51) for plasma glucose, insulin,
or urea-N. Plasma glucose, insulin, and urea-n levels were similar
between diets (P ≥ 0.35). Plasma glucose and urea-n levels were not different
across days (P ≥ 0.59). Insulin levels differed as a result of days of
adaptation and were greatest (P = 0.01) on d 12 regardless of diet. There
tended (P = 0.12) to be a diet x day
interaction for NEFA levels. Plasma NEFA levels tended to be lower (P = 0.13)
for calves fed CrP on d 5, and were greater (P = 0.09) on d 12 in calves fed
CrP. The shift in NEFA on d 12 coincided with the spike in insulin levels. Both
events occurred at the time that NEg intake was approaching the acclimated
plateau and neither event impacted glucose status. In non-ruminants, elevated insulin concentrations
decrease circulating NEFA levels. We detected minimal differences in regard to
plasma indicators of lipid metabolism in this study due to chromium
supplementation. These data indicate that ruminants may differ from
non-ruminants in the regulation and maintenance of glucose status and body fat
catabolism during the post-absorptive state.