Overfeeding energy increases visceral fat deposition and alters metabolic indices in Holstein cows

Our objective was to examine the effect of overfeeding a moderateenergy diet on performance, visceral depot weights, body condition score (BCS), body weight (BW), and blood metabolites in dry non-pregnant cows. Fourteen Holstein cows (BCS = 3.31 ± 0.14) were assigned to treatments in a randomized block design. All cows were fed individually a control diet (CON; NEL = 1.32 Mcal/kg) to meet 100% of NRC requirements for 3 wk, after which half of the cows were assigned to a moderate-energy diet (OVE; NEL = 1.54 Mcal/kg) and half of the cows continued on CON for 6 wk. The OVE diet was fed ad libitum and resulted in cows consuming energy at ~180% of NRC. CON cows were fed to consume only to 100% of NRC. The BW and BCS were measured from wk −3 to 6, while the blood samples were collected before slaughter and several metabolites and hormones were measured. The DMI was recorded from −1 wk through slaughter on a daily basis. The wk before slaughter, OVE cows had greater concentration of BHBA (0.43 vs. 0.22; P < 0.001), cholesterol (3.77 vs. 2.65; P = 0.008) and AST-GOT (78.77 vs. 64.33; P = 0.04); whereas, the concentration of NEFA (0.07 vs. 0.17; P = 0.002) and bilirubin (0.89 vs. 1.5; P = 0.005) was lower in OVE cows. OVE cows had greater (P < 0.001) BW (757.5 vs. 692.5), DMI (kg/d; 17.20 vs. 8.02) and DMI as a percentage of BW (2.20 vs. 1.18); whereas, the BCS (3.4 vs. 3.6) and empty carcass weight (468.43 vs. 525.91) remained unchanged. In OVE cows, weight of the mesenteric (15.49 vs. 8.1; P ≤ 0.01) and perirenal fat mass (11.17 vs. 3.39; P ≤ 0.04), and liver (11.4 vs. 7.82; P < 0.001) was greater. Omental fat mass (15.16 vs. 23.41) did not differ. The similar BCS between the 2 diets and the fact that OVE cows had greater internal fat deposition suggests that BCS provided little information on visceral fat mass. Overfeeding energy did not impair insulin sensitivity but seemed to affect hepatic function.