Influence of transition diets on the performance and metabolic profile of dairy cows both pre- and post-calving

The primary objective of this experiment was to compare the effects of ad libitum access to grass silage alone, or to a total mixed ration of grass silage and concentrates for the final 4 weeks of gestation on post-calving production performance. Sixty non-lactating Holstein-Friesian cows were blocked according to expected calving date, body condition score and live weight, and assigned at random to one of four treatments: silage (digestibility 773 g/kg dry matter) only pre-calving followed by a total mixed ration, containing proportionally either 0.35 or 0.55 concentrate, post-calving and a total mixed ration containing proportionally 0.3 concentrate pre-calving followed by a total mixed ration, containing proportionally either 0.35 or 0.55 concentrate, post-calving. Individual dry matter intake was measured at approximately 16 days pre-calving and 23 days post-calving. Blood samples were taken from the coccygeal vessels at the start of the experiment, at calving, and at 2 and 4 weeks post-calving to assess energy and protein status. There was no interaction between pre- and post-calving treatments. Post-calving milk yield (22.7 v. 23.3 kg/day, s.e.d. 1.01), milk protein concentration (33.4 v. 33.3 g/kg, s.e.d. 0.49), milk fat concentration (43.6 v. 43.3 g/kg, s.e.d. 1.06), daily live-weight loss (0.68 v. 0.57 kg, s.e.d. 0.146) and weekly body condition score loss (0.08 v. 0.09, s.e.d. 0.014) were not affected by pre-calving feeding treatment. Pre-calving dry matter intakes were not significantly different between treatments (8.1 kg/day for silage only v. 9.2 kg/day for total mixed ration, s.e.d. 0.66). At 2 weeks post-calving, blood metabolites indicated a superior nutritional status for the animals on the total mixed ration pre-calving. There was a significant increase in production performance with higher concentrate proportion post-calving. In this study post-calving performance was not improved by concentrate supplementation during the 4 weeks before parturition when the available forage was of high quality.