Susceptibility of dairy cows to subacute ruminal acidosis is reflected in both prepartum and postpartum bacteria as well as odd- and branched-chain fatty acids in feces

Table 2 Average DMI and reticular pH characteristics in the 1-week prepartum period (based on real calving dates) as well as the 3-week postpartum period in relation to variation in SARA susceptibility over the first 3 weeks postpartum¹

Item	Prepartum			SEM⁴	P-value	Postpartum				SEM⁴	P-value
Item	SU	MO	UN	SEM⁴	P-value	SU	MS	MU	UN	SEM⁴	P-value
Average DMI, kg/d	14.7	14.5	15.8	0.37	0.311	19.6	20.0	19.8	21.9	0.43	0.164
Reticular pH
Median time of pH below 6, min/d	193^a	13.3^a	0.00^b	31.870	0.006	321^a	46.4^b	10.0^c	0.0^d	26.75	< 0.001
Mean time of pH below 6, min/d	182^a	8.00^ab	0.00^b	31.933	0.014	356^a	104^b	32.5^c	2.78^d	26.963	< 0.001
Days with time of pH below 6 > 330 min/d²	1.30^a	0.00^b	0.00^b	0.256	0.004	8.82^a	1.57^b	0.00^c	0.00^c	0.775	< 0.001
Mean daily area under curve pH below 6³	185.9^a	8.44^a	0.00^b	36.476	0.006	882^a	293^b	50.1^c	3.85^d	77.548	< 0.001

¹Postpartum grouping: susceptible group (SU; n = 10): mean or median of time below pH 6 of at least 180 min/d; moderately susceptible group (MS; n = 7): 60 min/d < mean time of pH below 6 < 180 min/d and median time of pH below 6 < 180 min/d; moderately unsusceptible group (MU; n = 11): 10 min/d < mean time of pH below 6 < 60 min/d and median time of pH below 6 ≤ 30 min/d; unsusceptible group (UN; n = 10): median time pH below 6 = 0 min/d and mean time pH below 6 < 10 min/d. Due to early calving, 10 cows were from the SU group, the UN-group only contained 9 animals in the prepartum period and MS (n = 3) and MU (n = 7) cows were merged into a single group (MO, n = 10)
²Days with time of pH below 6 > 330 min/d during 7 d prepartum or 21 d postpartum
³Total area under the curve pH below 6.0 (pH × min) during 7 d prepartum or 21 d postpartum
⁴SEM = standard error of the mean
^a,bMeans within a row with different superscripts differ significantly (P ≤ 0.05)

ISSN: 2049-1891