. Author manuscript; available in PMC: 2019 Jun 13.

Published in final edited form as: J Dairy Sci. 2018 Oct 11;101(12):10911–10921. doi: 10.3168/jds.2018-15071

Table 2.

Effect of diet composition investigated in 3 experiments on the daily rhythm of rumination (% of day) fit as a cosine function with a 24-h period

Experiment¹	Amplitude²				Acrophase³				24-h Cosine fit⁴
1: Fiber	High NDF		Low NDF		High NDF		Low NDF		High NDF		Low NDF
	CONV	BMR	CONV	BMR	CONV	BMR	CONV	BMR	CONV	BMR	CONV	BMR
	0.046^a	0.048^ac	0.038^b	0.053^c	1302^a	1306^a	1447^b	1510^b	<0.001	<0.001	0.052	0.022
2: Starch	High starch		Low starch		High starch		Low starch		High starch		Low starch
	DG	HM	DG	HM	DG	HM	DG	HM	DG	HM	DG	HM
	0.101^a	0.118^c	0.085^b	0.070^d	1620^a	1649^c	1509^b	1616^a	<0.001	<0.001	<0.001	<0.001
	FA supplement				FA supplement				FA supplement
3: Fat	CON	SFA	UFA	MIX	CON	SFA	UFA	MIX	CON	SFA	UFA	MIX
	0.071^a	0.093^b	0.073^a	0.097^b	1241^a	1204^b	1159^b	1237^a	<0.001	<0.001	<0.001	<0.001

Experiment 1 was a 2 × 2 factorial design of brown midrib (BMR) and isogenic conventional (CONV) corn silage in a high (38%) or low (29%) NDF diet. Experiment 2 was a 2 × 2 factorial design of dry ground (DG) and high-moisture ground (HM) corn in a high (32%) and low (21%) starch diet. Experiment 3 used a low-fat control and 3 fatty acid supplements: CON = no-supplement fat control; SFA = prilled saturated fatty acid supplement (Energy Booster-100, Milk Specialties Inc., Eden Prairie, MN) at 2.5% of diet DM; UFA = calcium salts of unsaturated fatty acids (Megalac-R, Church and Dwight Co. Inc., Ewing, NJ) at 2.5% of diet DM; MIX = 50:50 mixture of SFA and UFA at 2.5% of diet DM.

Amplitude reported as the difference from peak to mean.

Acrophase is time at peak.

⁴

Cosine fit reported as the P-value of the zero-amplitude test.