Eating time of dairy cows: a study focusing on commercial farms

Figures & data

Table 1. Descriptive characteristics of 779 dairy cows and rations of the farms involved in the study.

Item	Total
	Mean	SD	Q25^1	Q75^1
Animal traits
Parity (n)	2.1	0.9	1	3
DIM (d)	182	111	102	249
Diet characteristics
Particle size (mm)	6.46	2.73	5.14	7.07
DM (%)	60.48	11.04	56.02	64.25
Ash (%DM)	7.14	0.76	6.85	7.49
CP (%DM)	14.98	1.69	13.81	16.84
EE (%DM)	2.89	0.64	2.39	3.34
NFC (%DM)	35.40	4.85	32.59	37.90
NDF (%DM)	39.58	6.16	34.13	43.96
ADF (%DM)	23.05	4.46	18.51	26.25
ADL (%DM)	4.18	1.10	3.18	5.26
NDFd (%NDF)	64.15	6.59	60.27	69.14
NEL (Mcal/kgDM)	1.48	0.17	1.36	1.63
peNDF (%DM)	40.97	6.71	36.42	43.54
Performance
FPCM (kg/d)	29.82	8.55	23.69	35.60
Milk Yield (kg/d)	30.41	9.11	24.49	36.50
Milk fat (%)	3.87	0.82	3.35	4.34
Milk protein (%)	3.42	0.29	3.21	3.61
Milk lactose (%)	4.80	0.29	4.74	4.97
Milk urea (mg/dL)	23.09	6.02	18.75	26.80
SCC (× 1000/mL)	214	515	33	142
BCS (points)	3.24	0.61	2.75	3.75
Behaviour
ET (min/d)	227.6	66.1	179.6	273.4
RT (min/d)	536.0	58.0	501.1	577.4
Feed management
Feed delivery (n/d)	1.50	1.22	1.00	1.00
Feed pushing (n/d)	11.43	10.01	3.50	24.00
COf (kg/d)	3.84	1.54	2.70	4.80

DIM: days in milk; DM: dry matter; CP: crude protein; EE: ether extract; NFC: nonfibre carbohydrates; NDF: neutral detergent fibre; ADF: acid detergent fibre; ADL: acid detergent lignin; NDFd: neutral detergent fibre degradability; NE_L: net energy for lactation; peNDF: physical effective NDF; FPCM: fat– and protein – corrected milk (Kok et al. 2016); SCC: somatic cell count; BCS: body condition score; ET: eating time; RT: rumination time; COf: compound feed offered; ¹Q_25: 25^th percentiles; Q₇₅: 75^th percentiles.

Figure 1. Results of the principal component analysis (PCA) analysis for the variable related to eating time class. a: component map with factor scores of numerical variables; b: component map with factor scores of levels. (a) FP: number of feed pushing per day; DIM: days in milk; ADL: acid detergent lignin (%DM); EE: ether extract (%DM); CP: crude protein (%DM); NFC: nonfibre carbohydrates (%DM); NDFd: neutral detergent fibre degradability (%NDF). (b) ETC: eating time class. ETC-1 ≤ 180 min/d; ETC-2 from >180 to ≤220 min/d; ETC-3 from >220 to ≤260 min/d; ETC-4 from >260 to ≤300 min/d; and ETC-5 > 300 min/d. Parity 1: primiparous; Parity 2: multiparous (2 parities); Parity 3: multiparous (>2 parities); HF: Holstein Friesian; IS: Italian Simmental.

Table 2. Estimated marginal means of milk yield and composition, body condition score and ruminating time as affected by eating time class and breed.

Item	Eating Time Class (ETC)^1					Breed		SEM	Breed, p -value	ETC, p-value	Contrasts, ETC p-values
	1	2	3	4	5	HF	IS				Linear	Quadratic
HF:IS ratio	27:73	29:71	39:61	36:64	23:77	–	–	–	–	–	–	–
Parity (n)	2.3	2.2	2.0	1.9	1.8	–	–	–	–	–	–	–
DIM (n)	199	170	185	183	170	–	–	–	–	–	–	–
Milk yield (kg/d)	27.04^E	28.72^D	29.89^C	30.23^B	31.91^A	30.60	28.46	0.058	<.01	<.01	<.01	.01
FPCM (kg)	26.71^e	27.97^d	29.28^c	29.54^b	31.08^a	29.56	28.21	0.059	<.01	<.01	<.01	.13
Milk composition
Fat (%)	3.87	3.84	3.82	3.87	3.77	3.77	3.90	0.213	.80	1.00	1.00	1.00
Protein (%)	3.45	3.44	3.40	3.39	3.41	3.37	3.47	0.196	.83	1.00	1.00	1.00
Lactose (%)	4.80	4.79	4.80	4.80	4.79	4.80	4.79	0.078	.96	1.00	1.00	1.00
Urea (mg/dL)	23.58^A	22.76^B	22.95^B	22.63^B	22.65^B	23.17	22.66	0.107	.03	<.01	<.01	<.01
SCC (x 1,000/mL)	224^a	255^a	189^a	179^a	118^b	222.5	157.1	11.36	.02	<.01	<.01	.13
BCS (points)	3.24^a	3.19^ab	3.10^ab	3.13^ab	3.05^b	2.81	3.47	0.024	<.01	.02	<.01	.72
RT (min/d)	520.9^E	531.3^C	532.3^B	528.7^D	536.1^A	540.1	519.8	0.06	<.01	<.01	<.01	<.01

¹ETC: eating time class. ETC-1 ≤ 180 min/d (n = 197); 220 min/d ≤ ETC-2 > 180 min/d (n = 179); 260 min/d ≤ ETC-3 > 220 min/d (n = 174); 300 min/d ≤ ETC-4 > 260 min/d (n = 111); ETC-5 > 300 min/d (n = 118). DIM: days in milk; FPCM: fat- and protein-corrected milk (Kok et al. 2016); SCC: somatic cell count; BCS: body condition score; RT: rumination time; HF: Holstein Friesian; IS: Italian Simmental; ^A, ^B, ^C, ^D, ^E means of ETC in the same row with different superscript are significantly different (p <.01); ^a, ^b, ^c, ^d, ^e means of ETC in the same row with different superscript are significantly different (p <.05).

Table 3. Correlation coefficient (r_s) between ETC and variables included in principal component analysis (PCA).

	Parity	Breed	DIM	FP	Particle size	CP	EE	ADL	NFC	NDFd
ETCt	–.18**	–.02	–.06	.30**	.44**	–.48**	–.46**	.54**	–.62**	–.59**
ETCHF	–.30**	–	.01	.32**	.52**	–.48**	–.45**	.51**	–.52**	–.52**
ETCtIS	–.13**	–	–.08	.27**	.42**	–.54**	–.58**	.57**	–.65**	–.67**

DIM: days in milk; FP: number of feed pushing per day; CP: crude protein (%DM); EE: ether extract (%DM); ADL: acid detergent lignin (%DM); NFC: nonfibre carbohydrates (%DM); NDFd: neutral detergent fibre degradability (%NDF); ETC: eating time class; Parity 1: primiparous; Parity 2: multiparous (2 parities); Parity 3: multiparous (>2 parities); breed: Holstein Friesian (HF), 1; Italian Simmental (IS). **: p < .01.

Kok A, van Middelaar CE, Engel B, van Knegsel ATM, Hogeveen H, Kemp B, de Boer IJM. 2016. Effective lactation yield: a measure to compare milk yield between cows with different dry period lengths. J Dairy Sci. 99(4):2956–2966. doi: 10.3168/jds.2015-10559.

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Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.