View Full Table | Close Full ViewTable 1.

Body weight and BCS of nonlactating dairy cows receiving diet to meet their ME requirements without Cr supplementation (MAN; n = 4), diet to exceed their ME requirements without Cr supplementation (HIGH; n = 4), or HIGH with 2.5 g/d of chromium propionate (HIGHCR; n = 5, with 10 mg of Cr/cow daily)1

 
Item HIGH HIGHCR MAN SEM P-value
Body weight, kg
    Initial BW (d 0), kg 702 658 707 48 0.72
    Final BW (d 88), kg 722 693 721 49 0.88
    Average BW during experiment, kg 712 675 714 49 0.80
    BW change, kg 20.5a 35.0b 14.0a 4.9 0.03
BCS2
    Initial BCS (d 0) 4.00 3.85 3.75 0.23 0.77
    Final BCS (d 88) 4.25 4.10 3.69 0.25 0.34
    Average BCS during experiment 4.12 3.97 3.72 0.23 0.51
    BCS change 0.25 0.25 –0.06 0.12 0.09
a,bMeans with different superscripts differ (P < 0.05).
1During the experimental period (d 0 to 88), MAN cows received (DM basis) 6.3 kg/d of a total-mixed ration (TMR) whereas HIGH and HIGHCR cows received 11.2 kg/d of the same TMR. Cows individually received the TMR through self-locking head gates twice daily (0700 and 1900 h), which were initially formulated to provide 100% of daily ME requirements of MAN cows and 177% of daily ME requirements of HIGH and HIGHCR cows. Chromium propionate (2.5 g of KemTrace 0.4% Cr; Kemin Agrifoods South America, Indaiatuba, São Paulo, Brazil) was mixed with 97.5 g of semolina and top-dressed daily into the TMR of HIGHCR cows.
2According to Wildman et al. (1982).



View Full Table | Close Full ViewTable 2.

Serum parameters and revised quantitative insulin sensitivity check index (RQUICKI) of nonlactating dairy cows receiving diet to meet their ME requirements without Cr supplementation (MAN; n = 4), diet to exceed their ME requirements without Cr supplementation (HIGH; n = 4), or HIGH with 2.5 g/d of chromium propionate (HIGHCR; n = 5, with 10 mg of Cr/cow daily)1

 
Item HIGH HIGHCR MAN SEM P-value
Weekly collections2
    Serum glucose, mg/dL 95.6a 91.1b 92.7ab 1.3 0.09
    Serum NEFA, mmol/L 0.176a 0.139b 0.144ab 0.012 0.08
    RQUICKI 0.578a 0.780b 0.841b 0.072 0.05
Glucose tolerance test3
    Glucose (area under the curve, mg/dL·min) 18,638 17,708 16,971 1,650 0.45
    Insulin (area under the curve, mg/dL·min) 6,324a 3,668b 4,918ab 1,394 0.04
    Glucose clearance rate, %/min 0.949 1.163 1.049 0.173 0.61
    Glucose half-life, min 101.7 77.4 78.1 21.9 0.68
a,bMeans with different superscripts differ (P < 0.05).
1During the experimental period (d 0 to 88), MAN cows received (DM basis) 6.3 kg/d of a total-mixed ration (TMR) whereas HIGH and HIGHCR cows received 11.2 kg/d of the same TMR. Cows individually received the TMR through self-locking head gates twice daily (0700 and 1900 h), which were initially formulated to provide 100% of daily ME requirements of MAN cows and 177% of daily ME requirements of HIGH and HIGHCR cows. Chromium propionate (2.5 g of KemTrace 0.4% Cr; Kemin Agrifoods South America, Indaiatuba, São Paulo, Brazil) was mixed with 97.5 g of semolina and top-dressed daily into the TMR of HIGHCR cows.
2Blood samples collected immediately before (0 h) and 2 h after the 0700 h feeding twice weekly (Mondays and Fridays) during the experiment for determination of serum glucose, insulin, and NEFA (0 h only) concentrations.
3Glucose tolerance tests were performed on d 32 and 88 by intravenously infusing cows with 0.5 g of glucose/kg of BW. Blood samples were collected at –15, 0, 10, 20, 30, 45, 60, and 90 min relative to infusion and analyzed for serum concentrations of glucose and insulin. Area under the curve for glucose and insulin were calculated with the trapezoidal method (Shiang, 2004). Glucose clearance rate and half-life were calculated with the equations described by Bernhard et al. (2012).