Table 29.

Effects of access to pasture (or outdoor loafing) on mastitis prevalence or mean somatic cell count of dairy cows

Country	System (a)	Group comparisons	Variable	Analysis (b)	Effect	Reference
Bacteriological findings (BACT)
DE	Tie‐stall, loose housing	Heifers on pasture vs. heifers indoors whole gestation	Bacteriological proof of IMI	MA	ns	Krömker et al. (2012)
USA	Loose‐housing, tie‐stall	Pasture vs. no‐pasture	Coliforms in BM	MA	ns	Cicconi‐Hogan et al. (2013)
Clinical mastitis (CM)
AT	Cubicle, straw yard, tie‐stall	Regular pasture access	CM	MA	↓	Cicconi‐Hogan et al. (2013)
AT	Loose housing, tie‐stall	Pasture: 0 day/year, 30–90 day/year, 91–199 day/year, 200–275 day/year	CM/cow and year	MA	ns	Schenkenfelder and Winckler (2021)
		outdoor run: 0 day/week, 1–2 day/week, 3–4 day/week, 5–7 day/week	CM/cow and year	MA	ns
CA	Cubicle, straw yard, tie‐stall	Pasture vs. confined	CM/100 cow‐years at risk	MA	ns	Levison et al. (2016)
CA	Tie‐stalls, cubicle, straw yards	Pasture access, confined	CM incidence heifers	MA	ns	Elghafghuf et al. (2014)
		Pasture assess during DIM 0–13 confined	CM incidence in primiparous DIM 0–13	MA	↓
IT	na	Pasture (7 months) vs. zero‐grazing	CM	UA	ns	Pugliese et al. (2021)
IT	Tie‐stall, cubicles	Pasture access vs. no pasture access	Medial treated CM	MA	↓	Zanon et al. (2021)
			Medical dry‐off	MA	↓
		Pasture period > 45 days vs. ≤ 45 days	Medial treated CM	MA	↓
			Medical dry‐off	MA	↓
PT	na	≥ 8 h/day grazing with mobile milking vs. confined	Estimated score 1–5	UA	ns	Medeiros et al. (2021)
USA	Cubicle, group Straw yard, pasture or dry lot, tie‐stall	Grazing vs. Non‐grazing	CM/305‐cow‐days at risk	UA	( ↓ )	Richert et al. (2013)
Somatic cell count (SCC)
DE	Tie‐stall, loose housing	Heifers on pasture vs. heifers indoors whole gestation	SCC > 100 (c)	MA	↓	Krömker et al. (2012)
DE	Cubicles	Pasture access vs. zero‐grazing	SCC > 400	MA	↓	Gieseke et al. (2020)
DE	na	Zero‐/minor grazing (0 to < 6 h), 6 to < 12 h pasture access, ≥ 12 h pasture access	SCC ≥ 400	MA	( ↑ ) (≥ 12 h)	Wagner et al. (2017)
IT	na	Pasture (7 months) vs. zero‐grazing	SCC	UA	↓	Pugliese et al. (2021)
IT	Cubicles	Pasture vs. Confined	log10n SCC	MA	↓	Di Grigoli et al. (2019)
NL	169 cubicle, 4 others	Day & night grazing, during‐ the‐day grazing, zero‐grazing	SCC > 150	MA	↓ (d)	Santman‐Berends et al. (2012)
PT	na	≥ 8 h/day grazing and mobile milking vs. confined	Estimated log10SCC	UA	( ↑ )	Medeiros et al. (2021)
USA	No‐housing, tie‐stall, straw yard, cubicle, compost	Pasture = no‐housing system vs. different housing systems	BMSCC	MA	( ↑ )	Eckelkamp et al. (2016a)
USA	Cubicles	Confined vs. any kind of outdoor access (yard or pasture)	SCS	MA	ns	Dechow et al. (2011)
	Tie‐stall		SCS	MA	ns (with component feed), ↑ (Total Mixed Ration – TMR)

↓ = significantly less mastitis during (increased) grazing (p < 0.05), ns = no significant (p ≥ 0.05) or (↑) marginal (p ≥ 0.1) effect.

^(a)Housing systems or husbandry practices used on the investigated farms.

^(b)Statistical analysis: MA = multivariable analysis; UA = univariable analysis.

^(c)Only primiparous cows.

^(d)Day and night grazing of lactating cows (−5.9%; 95% CI: −10.6 to −1.3%) compared to zero‐grazing (during‐the‐day‐grazing in‐between) (p = 0.01).