Consequential-based life cycle assessment of reducing the concentrates supply level in the diet fed to lactating cows in the alpine dairy farming system

Figures & data

Table 1. Descriptive statistics of farm area, herd composition (as livestock units -LU – with cattle >2 years: 1 LU, cattle 6 months to 2 years: 0.6 LU, cattle <6 months: 0.4 LU), and productive traits at the base scenario (t₀), before the reduction in the concentrate supply level (N = 40).

Variable	Unit	Mean	SD	Min	Max
Farm agricultural area (FAA)
FAA, permanent farm	ha	31	25	5	100
FAA, summer farm	ha	5	8	0	27
FAA, total	ha	36	27	5	107
Cropland	% FAA	3	7	0	28
Herd size
LU^1 dairy cows	N	31	21	5	99
LU lactating cows	N	27	18	4	86
LU replacement heifers	N	10	8	1	36
Stocking rate	LU/FAA	1.4	0.8	0.5	4.4
Productivity
Milk yield (fat and protein-corrected milk)	kg/dairy cow	6408	1632	3242	10336
Animal sold body weight (BW)	kg BW/LU	145	23	76	189
Concentrate supply level (CSL) as dry matter (DM)
Lactating cows	kg DM/head per day	4.5	2.8	1.1	11.3
Soybean meal, on CSL	% DM	17	13	0	50
Dry cows	kg DM/head per day	1.2	1.3	0.0	5.1
Soybean meal, on CSL	% DM	8	13	0	54
Replacement heifers	kg DM/head per day	0.6	0.4	0.1	1.6
Soybean meal, on CSL	% DM	9	18	0	100
Farm materials
Fuel	kg/LU	166	86	44	478
Electricity	kWh/LU	536	331	43	1648
Bedding (straw + sawdust)	kg/LU	504	534	0	1871

Table 2. Descriptive statistics of farms’ breeding composition and management traits (N = 40).

Variable		Percentage of farms
Breed composition	Simmental	50
	Mixed (different breeds and crossbreds)	18
	Holstein Friesian	17
	Brown Swiss	15
Housing	Stall loose	55
	Tie stall	45
Feeding administration	Total mixed ration	50
	Traditional feeding	50
Use of pasture, permanent farm	yes	65
	no	35
Use of pasture, permanent farm, by lactating cows	yes	48
	no	52
Use of pasture, summer farm	yes	48
	no	52
Use of pasture, summer farm, by lactating cows	yes	28
	no	72

Figure 1. Scheme for the ‘expanded_system’, covering the deficit in dairy products and fluid milk from the Alpine dairy system at t₁ (after the reduction in the concentrates supply level in the lactating cows’ rations) with respect to t₀ (base scenario).

Table 3. LSmeans and p-values of milk yield and diet composition for lactating cows at t₀, t₁75, and t₁50 (before and after reducing the proportion of concentrates in lactating cows’ diet, -25% in t₁75 and -50% in t₁50), per one lactating cow (N = 40). LSmeans with different superscripts (^a,b,c) within row differ significantly (p < 0.05).

	Unit	t0	t175	t150	p Value
Milk yield (fat- and protein-corrected milk, FPCM)	kg FPCM/d	21.0^a	19.1^b	17.4^c	<0.001
Dry matter (DM) intake	kg DM/d	19.6^c	19.2^b	18.7^a	<0.001
Net energy	MJ/kg DM	5.50^c	5.37^b	5.20^a	<0.001
Diet composition	kg DM/d
Hay		8.33^a	8.95^b	9.65^c	<0.001
Straw		0.09	0.09	0.09	0.32
Alfalfa hay		0.78	0.79	0.81	0.06
Grass silage		0.92	0.95	0.98	0.14
Maize silage		1.15	1.18	1.20	0.06
Concentrates		4.48^c	3.40^b	2.30^a	<0.001
Grass at pasture		3.89	3.83	3.82	0.06
Forage: concentrate ratio	.	75:25^a	79:21^b	84:16^c	<0.001
Diet self-sufficiency	%	67.9^a	70.3^b	73.1^c	<0.001

Figure 2. LSmeans and p-value of the impact categories and potentially human-edible energy conversion ratio, computed for the dairy farms plus dairy processing system and (N = 40). Three scenarios tested: 100% (t₀), 75% (t₁75) and 50% (t₁50) of the initial concentrate supply level in the rations fed to the lactating cows.

Figure 3. LSmeans and p-value of the single gases contribution (a) and land-based CO₂ (b) contributing to the global warming potential for dairy farms plus dairy processing system (N = 40). Three scenarios tested: 100% (t₀), 75% (t₁75) and 50% (t₁50) of the initial concentrate supply level in the rations fed to the lactating cows. Credit due to body weight sold and avoided production of mineral fertilisers.

Figure 4. LSmeans and p-value of the impact values, the system expanded to cover the product deficit in the Alpine dairy system (N = 40), covering based on Italian lowland fluid milk (a) or soy drink (b). Results were reported for the three tested scenarios: 100% (t₀), 75% (t₁75) and 50% (t₁50) of the initial concentrate supply level in the rations fed to the lactating cows.

Data availability statement

The data presented in this study are available on request from the corresponding author upon reasonable request.