Effects of Diet Energy Levels Fed During the Dry Period on Performance Parameters of Dairy Sectors21 May 2013
Dry cow feeding could affect dry matter intake and milk protein content, according to research undertaken at the University of Illinois that explored energy levels.
Metabolic disorders during early lactation are linked to energy intake during the dry period. Controversy arises whether controlling energy intake during the dry period would compromise cow performance after parturition.
The aim of this study was to assess if controlling energy intake during the dry period has negative effect on cow performance during early lactation.
Twenty-seven multiparous Holstein cows dried-off 50d before expected calving date were blocked by lactation, body weight (BW), body condition score
(BCS) and randomly assigned to one of three dry period diets.
Dietary treatments were: controlled-energy group (CE; n=11), fed a high-fiber diet to supply 100 per cent of NRC requirements for energy and all nutrients ad libitum; high-energy group (HE; n=7), fed a diet formulated to supply 160-180 per cent of energy (NEL) requirements at ad libitum intake; and restricted energy group (RE; n=8), fed to 80 per cent of their calculated NEL requirements by controlled intake of the high-energy ration.
After calving a single lactation diet to supply 100 per cent NRC requirements was fed to all cows. BW and BCS were measured weekly. Milk production and DMI were recorded daily.
Milk samples were collected twice weekly and analyzed for fat, protein, lactose, urea nitrogen (MUN), and somatic cell count (SCC). Cows remained in the experiment until 28d after calving. Data were analyzed using the MIXED procedure of SAS.
Results and Conclusion
Cows fed HE diet ad libitum had greater DMI (P < 0.001) during the dry period while cows fed the same diet at RE intake had lower BW (P = 0.08). In addition, a significant (P = 0.02) interaction of treatment by was observed for DMI during the dry period.
Despite no difference in milk production (P = 0.83), cows fed CE diet had higher milk protein content (P = 0.04) when compared RE fed cows. Fat, lactose, and SSC concentrations did not differ among treatments. A significant (P < 0.05) interaction of treatment by wk was observed for milk protein and MUN concentrations. After parturition, cows previously fed CE and RE diets during the dry period performed similarly to HE fed cows.