Prepartum dietary energy strategies for Holstein dairy cows: Effects on markers of negative energy balance and performance

Abstract Text:

Study objectives were to compare different dry cow nutritional strategies and their influence on peripartal concentrations of β-hydroxybutyrate (BHBA) and nonesterified fatty acids (NEFA) as analytes related to negative energy balance and periparturient dry matter intake (DMI) and milk yield. Cows (n=84) were dried off 57 d before expected calving and assigned to one of three diets: a controlled-energy diet (L) that was formulated to meet, but not greatly exceed, energy requirements for the entire dry period; a step-up approach (I) in which animals received diet L for the first 4 wk of the dry period and after that a diet supplying 125% of energy requirements until calving; and a higher energy diet (H) formulated to contain 150% of requirements for the entire dry period. Data measured over time were subjected to repeated measures ANOVA using PROC MIXED with treatment, time and parity as fixed effects (Table 1). Energy content was 1.28, 1.35 and 1.42 Mcal NEl/kg DM for the L, I and H diets respectively. Animals fed L had lower concentrations of BHBA during both the prepartum and postpartum periods than cows fed H. Concentration of NEFA in cows fed L was higher prepartum compared with the other two treatments, while being lower in cows fed L or I compared with H postpartum. Yields of milk and energy-corrected milk (ECM) were not different among treatments. Although sample size was not sufficient to study health outcomes, results suggest positive effects on metabolic health by feeding a controlled energy diet during the dry period.

Table 1. Least squares means for energy metabolites, DMI and milk yield.

Parameter		Treatment				Fixed effects
		L	I		H	Treatment	Treatment x Time
		LS means ± SE				p
BHBA,            mmol/dL	prepartum	0.29 ± 0.01a	0.30 ± 0.01ab	0.34 ± 0.01b		0.04	0.03
	postpartum	0.63 ± 0.06a	0.77 ± 0.06ab	0.85 ± 0.06b		0.05	0.19
NEFA,     uEq/L	prepartum	237.1 ± 12.4a	179.5 ± 12.7b	175.4 ± 12.5b		0.001	0.03
	postpartum	659.1 ± 36.4a	664.6 ± 36.7a	795.7 ± 39.5b		0.02	0.37
DMI,         kg/d	prepartum	14.2 ± 0.3a	15.3 ± 0.3b	16.4 ± 0.3c		˂0.0001	0.03
	postpartum	22.3 ± 0.6	22.4 ± 0.6	22.4 ± 0.6		0.99	0.75
Milk yield, kg/d		43.8 ± 1.2	43.6 ± 1.2	43.9 ± 1.2		0.98	0.31
ECM yield, kg/d		46.1 ± 1.2	47.0 ± 1.2	48.3 ± 1.3		0.48	0.94

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Keywords:

Energy, peripartal, controlled