Studies On Different Energy Density Of Close-up Diets On Energy Metabolism And Ruminal Adaption In Multiparous Holstein Cows

The objective of these experiments were to evaluate the effects of prepartum dietary energy density and dietary supplementation with sodium butyrate and calcium propionate on dry matter intake (DMI), lactation performance, energy metabolism, ruminal adaption, immunity and antioxidant capacity in multiparous Holstein cows.Part one was to determine the effects of reduced energy density of close-up diets on DMI, lactation performance and energy metabolism in multiparous Holstein cows. Thirty-nine dry cows were blocked and assigned randomly to three groups fed a high energy density diet [100NRC;6.8MJ of net energy for lactation (NEL)/kg], or a middle energy density diet (90NRC, n=13;6.2MJ NEL/kg), or a low energy density diet (80NRC, n=13;5.4MJ NEL/kg) from21day before expected day of calving. After parturition, all cows were fed the same lactation diet to70day in milk (DIM). The DMI and NEL intake prepartum were significantly decreased by the reduced energy density diets (P<0.05). The80NRC group consumed26.1%and63.2%more DMI and NDF, respectively, compared with100NRC group in the last24h before calving. The DMI, NEI and NDF intake of the first5wk of lactation, milk yield of the first10Wk of lactation and the milk lactose content of the first3wk of lactation were increased by the reduced energy density diet (P<0.05). The energy consumption for100NRC,90NRC and80NRC groups were149.8%,126.2%and101.1%of their calculated energy requirements prepartum(P<0.05), and72.7%,73.1%and75.2%during the first4wk postpartum, respectively. The reduced energy density diet increased the content of prepartum NEFA and postpartum glucose, decreased the postpartum NEFA and BHBA content (P<0.05). The hepatic PC mRNA abundance was improved (P=0.08), and the subcutaneous adipose HSL mRNA abundance was depressed (P<0.05) by the reduced energy density diet on3DIM. In conclusion, the prepartum reduced energy density diet was effective in controlling DMI change rate prepartum, and was beneficial in increasing DMI and milk yield, and decreasing the adipose tissue mobilization and alleviating negative energy balance postpartum.Part two was to evaluate the effects of reduced energy density of close-up diets on ruminal adaption in multiparous Holstein cows. Fourteen dairy cows were enrolled in the trail. The experimental design was same to part one. The ruminal pH of80NRC group was higher prepartum and lower during the first4wk of lactation compared with90NRC and100NRC groups (P<0.05).80NRC group had3sampling points of pH below5.6, which was determined at hourly intervals on7and8DIM, while there were not any for90NRC and100NRC groups. The reduced energy density diet depressed the average ruminal concentration of propionate and butyrate prepartum, and increased the concentration of volatile fatty acids (VFA), and decreased the ratio of acetate to propionate postpartum (P<0.05). The Fibrobacter succinogenes population for100RNC group was lower than that for90NRC and80NRC groups prepartum.80NRC group had higher population of Butyrivibrio fibrisolvens and Ruminococcus flavefaciens relative to100NRC and90NRC groups, and higher Megasphaera elsdenii population compared with100NRC group on7DIM. The results indicated that the cows fed reduced energy density diet prepartum had higher VFA concentration, but were more susceptible to subacute ruminal acidosis postpartum.Part three was to determine the effects of reduced energy density of close-up diets on immunity and antioxidant capacity in multiparous Holstein cows and newborn calves. The experimental design and cows were same to part one. The lower energy density diets increased the concentration of T-AOC and IL-4during the postpartum, and the concentration of T-AOC on the parturition day, and decreased the IgG concentration of colostrum (P<0.05). The immunity and antioxidant capacity of newborn calves at0h and24h were not affected by maternal energy intake during the close-up period.Part four was to estimate the effects of sodium butyrate and calcium propionate supplementation during close-up period on lactation performance, energy metabolism and ruminal fermentation in multiparous Holstein cows. Forty-five dairy cows were blocked and assigned randomly to1of3treatments. All the cows fed the same diet from-21d to28DIM which was same to the80NRC group diet of part one, and added0g/d (Control group),200g/d (1.5%group) and400g/d (3.0%group) sodium butyrate and calcium propionate to the3treatment diets during the close-up period, respectively. Sodium butyrate and calcium propionate supplementation increased the DMI on the parturition day(P<0.05), but had no effect on DMI prepertum and postpartum (P>0.05), improved the concentration of ruminal TVFA and acetate and blood glucose on-7d, and decreased NEFA concentration postpartum (P <0.05). The milk yields for1.5%and3.0%groups were1.21and1.07kg/d more than control group, respectively, during the first4wk of lactation(P>0.05). The results indicated that sodium butyrate and calcium propionate supplementation was beneficial in increasing DMI and milk yield, and alleviating negative energy balance during transition period.