Effect of precalving and postcalving dietary energy level on performance and blood metabolite concentrations of dairy XXXX throughout lactation.

@entity62 @entity291 @entity844
The effects of the level of energy intake (high E and low E) offered before and after calving on body condition score at calving, production performance, and energy status in the first 250 d of lactation were evaluated in a 2   2 factorial design experiment involving 80 Holstein-Friesian dairy animals (40 primiparous and 40 multiparous). From d 80 until d 21 precalving, primiparous animals were offered either high or low pasture allowances. Thereafter, these animals were housed and had ad libitum access to a high energy density diet (high E) or restricted access [6 kg of @entity62 ( @entity62 ) per d] to a low energy density diet (low E), respectively, until calving. From d 100 until d 42 precalving, multiparous animals were offered either ad libitum or restricted (10 kg of @entity62 /d) access to a late lactation diet, and thereafter, had ad libitum access to a high E diet or restricted access (7 kg of @entity62 complete diet/d) to a low E diet, respectively, until calving. The forage to concentrate (F:C) ratios ( @entity62 basis) of these high E and low E diets [d 42 (d 21 in primiparous animals) until calving] were 64:36 and 83:17, respectively. @entity291 offered high E and low E precalving diets were allocated to either a high E or low E postcalving diet [F:C ratio ( @entity62 basis) of 30:70 and 70:30, respectively] and remained on these diets until d 250 of lactation. Multiparous animals offered a high E diet precalving had a significantly higher body condition score at calving than those offered the low E diet precalving. This effect was not evident in primiparous animals. Precalving diet had no significant effect on plasma nonesterified @entity844 concentrations during the last 3 wk precalving in primi- or multiparous animals. Primiparous animals offered a high E diet precalving had significantly higher postcalving plasma concentrations of nonesterified @entity844 , suggesting greater mobilization of body reserves. Primi- and multiparous animals offered a high E diet postcalving had a significantly higher @entity62 intake, milk yield, and energy status postcalving compared with animals offered a low E diet postcalving. Milk yields of primiparous animals offered high E and low E diets postcalving were 29.7 and 24.8 kg/d, respectively, and milk yield of multiparous animals offered high E and low E diets postcalving were 33.5 and 28.2 kg/d, respectively. It is concluded that altering body condition score during the dry period is difficult but that specific dietary regimens applied precalving can have a significant influence on postcalving production and energy-related parameters.
