An experiment was conducted to determine the effect of prepartum plane of energy intake on metabolic profiles related to lipid metabolism and health in blood and liver.
Primiparous (n=24) and multiparous (n=23) Holsteins were randomly assigned by expected date of parturition to one of three prepartum energy intakes. A high energy diet [1.62 Mcal of net energy for lactation (NEL)/kg; 15 percent crude protein] was fed for either ad libitum intake or restricted intake to supply 150 percent (OVR) or 80 percent (RES) of energy requirements for dry cows in late gestation. To limit energy intake to 100 percent of National Research Council requirements at ad libitum intake, chopped wheat straw was included as 31.8 percent of dry matter for a control diet (CON; 1.21 Mcal of NEL/kg of dry matter; 14.2 percent crude protein).
Regardless of parity group, OVR cows had greater concentrations of glucose, insulin, and leptin in blood prepartum compared with either CON or RES cows; however, dietary effects did not carry over to the postpartum period. Prepartum nonesterified fatty acids (NEFA) were lower in OVR cows compared with either CON or RES cows. Postpartum, however, OVR cows had evidence of greater mobilization of triacylglycerol (TAG) from adipose tissue as NEFA were higher than in CON or RES cows, especially within the first 10 d postpartum. Prepartum β-hydroxybutyrate (BHBA) was not affected by diet before parturition; however, within the first 10 d postpartum, OVR cows had greater BHBA than CON or RES cows. Prepartum diet did not affect liver composition prepartum; however, OVR cows had greater total lipid and TAG concentrations and lower glycogen postpartum than CON or RES cows. Frequency of ketosis and displaced abomasum was greater for OVR cows compared with CON or RES cows postpartum. Controlling or restricting prepartum energy intake yielded metabolic results that were strikingly similar both prepartum and postpartum, independent of parity group.
The use of a bulky diet controlled prepartum energy intake in multiparous and primiparous cows, improved metabolic status postpartum, and reduced the incidence of health problems. When metabolic profiles are considered collectively, cows overfed energy prepartum exhibited an "overnutrition syndrome" with characteristics of clinical symptoms displayed by diabetic or obese nonruminant subjects. This syndrome likely contributed to metabolic dysfunction postpartum.
Source: N. A. Janovick, Y.R. Boisclair, J.K. Drackley/Journal of Dairy Science