Recombined, late harvested ensiled alfalfa leaves and stems give comparable performance to normally harvested alfalfa silage

Abstract Text: Increased use of the perennial forage, alfalfa, on dairy farms could be accomplished by reducing the number of harvests, separately storing leaves and stems, and feeding at a ratio that maintains lactation performance. More use of alfalfa could also decrease the environmental impact of dairies. We compared the impact on lactation performance of normally harvested alfalfa silage (early bud stage) with a blend of separately harvested and ensiled alfalfa leaves and stems obtained from more mature plants (full bloom stage). Forty-four primiparous cows were randomly assigned to one of two diets using a randomized complete block design with a 2-week covariate period followed by a 3-week experimental period. Lactation performance was measured in the last week of each period. Experimental diets were formulated to provide similar concentrations of crude protein (CP) and neutral detergent fiber (NDF) by blending two whole-plant alfalfa silages (WP), or by blending separately ensiled alfalfa leaves and stems (LS). Urea (0.27%), as diet dry matter (DM), was added to LS to give equivalent CP. Diets were 60% forage, 17.2% CP, 24% starch, 26% ensiled alfalfa, and 34% corn silage on a DM basis. Milk production, energy-corrected milk production, and efficiencies of use of DMI and N did not differ between treatments. Milk urea nitrogen differed between treatments, but by less than 1 mg/dl. This may be due to slightly lower digestibility of LS vs. WP, or to the addition of urea, which likely differed from the soluble protein present in WP. Blending leaves and stems gave similar production performance as normally harvested alfalfa silage, but with the advantage that harvesting alfalfa leaves separate from stems allows large biomass accumulation in the field and fewer harvests.

Measure	WP	LS	SED	p-value
DMI, kg	23.8	23.9	0.62	0.82
Milk, kg	42.5	41.1	1.11	0.23
ECM, kg	45.2	44.3	1.37	0.52
MUN, mg/dl	10.7	11.5	.26	<0.01
ECM/DMI	1.92	1.86	0.09	0.50

Keywords: forage, alfalfa, dairy