Different methods of eubiotic feed additive provision affect the health, performance, fermentation, and metabolic status of dairy calves during the preweaning period

Table 3 The effect of different methods of eubiotic feed additive provision on ruminal fermentation in dairy calves

Item	Time (day)²	Treatment¹				SEM	P-values
Item	Time (day)²	CON	MR	SF	MRS	SEM	P-values
Ruminal pH	28	5.29	5.72	5.71	5.59	0.02	0.49
Ruminal pH	56	6.04	6.20	6.44	6.21	0.08	0.53
SCFA³ molar concentrations (mmol/L)
Total SCFA	28	39.8	37.4	38.2	36.6	0.20	0.19
Total SCFA	56	70.6^b	79.2^a	75.3^ab	76.5^ab	0.11	0.012
Acetate	28	21.9	19.2	21.4	19.4	0.11	0.25
Acetate	56	32.2	32.9	35.7	34.5	0.09	0.25
Propionate	28	12.8	12.4	11.2	11.7	0.24	0.30
Propionate	56	27.7^b	32.2^a	27.3^b	29.3^ab	0.66	0.037
N-butyrate	28	3.76	4.70	4.35	4.26	0.06	0.19
N-butyrate	56	7.95^b	10.9^a	9.28^ab	9.48^ab	0.04	0.022
N-valerate	28	1.38	1.07	1.26	1.20	0.01	0.34
N-valerate	56	2.75	3.18	3.06	3.22	0.04	0.25
C₂: C₃ ratio⁴	28	1.71	1.64	1.73	1.73	0.08	0.08
C₂: C₃ ratio⁴	56	1.16	1.12	1.11	1.26	0.02	0.25
C₄: C₅ ratio⁵	28	2.72	4.39	3.45	3.55	0.06	0.09
C₄: C₅ ratio⁵	56	2.89	3.42	3.03	2.94	0.06	0.42
NH₃-N (mmol/L)	28	21.2	13.2	19.5	17.5	1.38	0.16
NH₃-N (mmol/L)	56	14.3	12.4	16.2	15.1	1.60	0.12

¹Treatment CON (control: without eubiotic feed additive in their milk replacer or their starter feed: n = 11), MR (eubiotic feed additive added to their milk replacer: n = 11), SF (eubiotic feed additive added to their starter feed: n = 11), MRS (eubiotic feed additive added to their milk replacer and their starter feed: n = 11)
²Time age of calf (day)
³ SCFA short-chain fatty acids
⁴C₂: C₃ ratio the ratio of ruminal acetate to propionate
⁵ C₄: C₅ ratio the ratio of ruminal butyrate to valerate, ^a–b Means within a column with different superscripts differ (P ≤ 0.05)

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