Effect of dry period length on rumen adaptation in dairy cows

Abstract

The objective of this study was to evaluate the effect of length of dry period on rumen papillae dimensions of dairy cows around parturition. Twelve rumen-cannulated Holstein dairy cows were assigned to a dry period length of 60 (G60), 30 (G30) or 0 (G0) days. The experiment started 60 d before expected calving date and lasted until wk 8 postpartum for each individual cow. Cows received ad libitum forage mixtures of corn silage, grass silage and straw (containing 12% CP, 5.3 MJ NEL/kg DM for dry cows and 15% CP, 6.4 MJ NEL/kg DM for lactating cows). Concentrates were fed individually starting 10 d antepartum with 1.0 kg/d, gradually increasing up to 8.5 kg/d at d17 postpartum. Milk yield and DMI were recorded daily. The rumen contents of each cow were evacuated at wk-9, wk-6, wk-2, d3, d7, d14, d28 and d56 relative to parturition. At each time, biopsies were taken to determine papillae dimensions at 3 locations: the right dorsal sac cranially of the dorsal coronary groove (DS), the right wall of the caudodorsal blind sac (DB) and the ventral wall of the caudoventral blind sac (VB). Treatment effects were tested by mixed model analysis using REML procedure. Data are presented as means ± SE. Mean DMI postpartum was 21.2, 22.2 and 23.7 (±0.6 kg/d) for G60, G0 and G30 respectively (P <0.05). Average daily milk yield postpartum was significantly lower for G0 (P <0.05) compared with G30 or G60 (35.1 vs. 41.4 and 41.8 ± 3.1 kg/d, respectively). For cows with a dry period (G30 and G60), papillae surface area decreased prepartum (P <0.05). More importantly, during the first 2 weeks postpartum the papillae growth was significantly delayed for G60 compared with G30; mean papilla surface was 42.5, 58.6 and 60.6 (±7.1, P <0.05) mm2 for G60, G30 and G0 respectively. Irrespective of treatment, rumen papillae were largest at VB and smallest at DS and papilla surface increased approximately 50% postpartum (P <0.05). In conclusion, a shortened dry period of 30 vs. 60 d increases papillae surface in the first weeks of lactation and herewith may improve absorption capacity of volatile fatty acids, without a negative effect on milk yield as found with 0 d dry