Effects of different forage to concentrate ratios on performance, plasma metabolites, and feeding behaviour of weaned dairy calves from 70 to 120 days of age

Figures & data

Table 1. Ingredients, chemical composition and particle size of treatments.

	Forage: concentrate ratio
Item	20:80	35:65	50:50
Ingredients, % of DM
Alfalfa hay	20.0	35.00	50.0
Ground corn	31.1	24.70	18.60
Ground barley	17.9	13.40	10.30
Soybean meal	16.1	14.70	13.0
Wheat bran	11.7	9.00	5.0
Bicarbonate sodium	0.70	0.70	0.70
Mineral supplement^a	0.40	0.40	0.40
Vitamin supplement^b	0.40	0.40	0.40
Di-calcium phosphate	0.50	0.50	0.50
Salt	0.40	0.40	0.40
Calcium carbonate	0.60	0.60	0.50
Magnesium oxide	0.20	0.20	0.20
Chemical composition, % of DM
DM, % of as fed	89.40	90.10	90.0
OM	91.90	91.20	90.70
CP	17.00	16.80	16.40
Ether extract	2.90	2.60	2.30
NDF	25.20	29.90	34.20
ADF	10.90	14.20	18.50
NFC^c	46.80	41.90	37.80
NFC:NDF ratio	1.850	1.40	1.10
Starch	36.70	29.0	22.10
ME^d, Mcal/kg DM	2.71	2.52	2.33
% of DM retained on sieves
19.00 mm	8.20	10.10	19.50
8.00 mm	9.80	13.70	12.90
1.18 mm	28.50	23.20	21.90
Pan	53.40	52.90	45.60
peNDF8,^e % of DM	4.59	6.85	10.27
peNDF1.18,^e % of DM	11.86	13.53	17.21
GMPS^f, mm	2.02	2.30	3.39
SDPS^f, mm	2.37	2.53	2.87

DM: dry matter; OM: organic matter; CP: crude protein; NDF: neutral detergent fiber; ADF: acid detergent fiber. ^aContained (mg/kg): Co, 150; Cu, 4000; I, 170; Mn, 10,000; Zn, 16,000; Fe, 600; Ca, 240,000; Se, 90; monensin, 2000.

^bContained (U/kg): vitamin A, 1,200,000; vitamin D, 350,000; vitamin E, 12,000; biotin, 200 mg/kg.

^cNFC calculated as 100 – (% NDF + % CP + % ether extract + % ash) (NRC 2001).

^dMetabolizable energy was calculated using NRC (2001) equations with the values from the analyses for diet.

^epeNDF₈ and peNDF_1.18 = physically effective NDF determined as NDF content of forage or diet multiplied by physical effectiveness factor > 8 and physical effectiveness factor > 1.18, respectively.

^fGeometric mean of particle size (GMPS) and standard deviation of particle size (SDPS) were calculated as described by the American Society of Agricultural Engineers (ASABE 2003, method S319.3).

Figure 1. Mean dry matter (DM) intake (kg) in calves (15 per treatment) fed diets with different forage to concentrate ratio. Error bars represent the standard error of the mean at each time point. Values are shown separately for Holstein calves fed diet forage-to-concentrate ratio of 50:50 (F50; ●); forage-to-concentrate ratio of 35:65 (F35; ^), and forage-to-concentrate ratio of 20:80 (F20; ▼). During the study, p-values for the linear effects of treatments, day and interaction between treatments and day were .008, < .0001 and .89, respectively and SEM was .050.

Table 2. Dry matter intake, energy intake, body weight (BW), average daily gain (ADG), and feed conversion ratio for weaned Holstein heifers (n = 15 per treatment) fed diets with different forage to concentrate ratio.

	Forage: concentrate ratio			SEM	Contrast p-value
Items	20:80	35:65	50:50		Linear	Quadratic
Dry matter intake, kg/d
d 70–95	2.98	2.86	2.76	0.060	0.001	0.91
d 96–120	4.16	3.98	3.91	0.077	0.020	0.56
Overall (d 70–120)	3.57	3.42	3.34	0.050	0.002	0.60
Energy intake, Mcal/d
d 70–95	8.19	7.45	6.92	0.252	0.001	0.68
d 96–120	11.43	10.46	9.86	0.277	0.002	0.52
Overall (d 70–120)	9.81	8.96	8.41	0.250	0.0003	0.61
Average daily gain, kg/d
d 70–95	1.06	0.94	0.89	0.039	0.004	0.44
d 96–120	1.11	0.95	0.96	0.046	0.020	0.14
Overall (d 70–20)	1.08	0.94	0.93	0.032	0.001	0.14
Gain to feed ratio
d 70–95	0.35	0.33	0.32	0.008	0.01	0.52
d 96–120	0.26	0.23	0.24	0.011	0.13	0.21
Overall (d 70–120)	0.30	0.27	0.27	0.008	0.02	0.20
Energy to gain ratio, Mcal/kg
d 70–95	7.77	7.95	7.88	0.227	0.72	0.64
d 96–120	10.30	12.20	10.50	1.010	0.88	0.16
Overall (d 70–120)	9.10	10.10	9.20	0.560	0.84	0.18
BW, kg
d 70	71.50	72.40	71.10	1.430	0.84	0.55
d 95	98.20	94.70	94.30	0.950	0.005	0.17
d 120	126.20	119.60	118.40	1.240	0.0001	0.06
Faecal score	1.23	1.30	1.07	0.117	0.32	0.30
Days with score ≥ 3	0.40	0.53	0.13	0.140	0.19	0.13
Health score	1.01	1.04	1.01	0.009	0.85	0.02
Days with score ≥ 2	0.80	2.06	0.66	0.422	0.82	0.01

SEM: standard error of the mean. Faecal score = 1–4 (1 = normal, 2 = soft, 3 = runny, and 4 = watery).

Health score = 1–3; (1 = normal, alert and no incidence of cough; 2 = slightly impaired, sporadic coughing, lop-eared, watery discharge or dry nose, slight watering eyes, swollen and without discharge navel; 3 = severely impaired, repeated coughing, purulent discharge nose, swollen and with discharge navel).

Table 3. Ruminal pH (n = 15 per treatment) and total tract nutrient digestibility (n = 8 per treatment) for weaned Holstein heifers fed diets with different forage to concentrate ratio.

	Forage: concentrate ratio			SEM	Contrast p-value
Items	20:80	35:65	50:50		Linear	Quadratic
Ruminal pH
d 95	6.42	6.95	6.62	0.114	0.22	0.005
d 120	6.23	6.55	6.72	0.109	0.004	0.61
Digestibility, % of DM
DM	79.2	72.5	79.8	2.590	0.87	0.03
OM	81.1	78.8	81.6	2.290	0.89	0.37
CP	76.1	76.5	81.7	2.580	0.14	0.44
EE	81.3	77.9	76.7	3.160	0.31	0.79
NDF	68.1	60.7	63.5	1.910	0.12	0.05
ADF	61.7	50.1	58.8	2.530	0.42	0.002

SEM: standard error of the mean; DM: dry matter; OM: organic matter; CP: crude protein; NDF: neutral detergent fiber; ADF: acid detergent fiber.

Table 4. Structural parameters for weaned Holstein heifers (n = 15 per treatment) fed diets with different forage to concentrate ratio.

	Forage: concentrate ratio			SEM	Contrast p-value
Items	20:80	35:65	50:50		Linear	Quadratic
Heart girth, cm
d 95	102.3	102.0	101.3	0.53	0.16	0.80
d 120	112.5	110.5	109.1	0.69	0.001	0.74
Abdominal girth, cm
d 95	124.2	126.1	126.3	0.93	0.12	0.43
d 120	137.8	136.7	138.2	1.37	0.82	0.45
Withers height, cm
d 95	90.8	90.4	89.5	0.41	0.02	0.68
d 120	97.0	96.2	94.7	0.45	0.001	0.51
Hip height, cm
d 95	95.6	95.2	94.8	0.47	0.24	0.95
d 120	101.8	101.2	100.2	0.50	0.04	0.78
Hip width, cm
d 95	23.8	23.6	23.5	0.22	0.29	0.98
d 120	26.9	26.2	26.3	0.24	0.08	0.30

SEM: standard error of the mean.

Table 5. Plasma metabolites for weaned Holstein heifers (n = 8 per treatment) fed diets with different forage to concentrate ratio.

	Forage: concentrate ratio			SEM	Contrast p-value
Items	20:80	35:65	50:50		Linear	Quadratic
Glucose, mg/dL
d 95	104.3	99.3	92.5	2.86	0.006	0.79
d 120	112.0	100.3	103.7	3.88	0.14	0.13
Cholesterol, mg/dL
d 95	64.6	67.6	71.0	4.48	0.33	0.96
d 120	71.9	76.0	73.6	4.57	0.80	0.56
Blood urea nitrogen, mg/dL
d 95	25.07	32.3	34.5	2.42	0.01	0.40
d 120	32.7	31.0	37.3	1.90	0.09	0.10
β-hydroxybutyric acid, mmol/L
d 95	0.24	0.42	0.43	0.034	0.001	0.05
d 120	0.25	0.31	0.29	0.043	0.46	0.41
Total protein, g/dL
d 95	6.9	7.2	7.0	0.14	0.75	0.23
d 120	7.2	7.1	7.0	0.21	0.78	0.81
Albumin, g/dL
d 95	3.7	3.8	3.7	0.08	0.52	0.53
d 120	3.8	3.8	3.8	0.07	0.53	0.92
Globulin, g/dL
d 95	3.2	3.3	3.2	0.11	0.90	0.61
d 120	3.4	3.2	3.3	0.15	0.87	0.70

SEM: standard error of the mean.

Table 6. Total time devoted to performing different behaviours during 8 h of observation for weaned Holstein heifers (n = 15 per treatment) fed diets with different forage to concentrate ratio.

	Forage: concentrate ratio			SEM	Contrast p-value
Items	20:80	35:65	50:50		Linear	Quadratic
Standing, min	82.3	73.4	67.7	9.98	0.14	0.81
Lying, min	190.6	151.2	159.3	14.86	0.04	0.06
Eating, min	96.3	114.5	109.1	11.54	0.27	0.24
Rumination, min	80.7	102.7	116.7	7.92	0.002	0.66
Non-nutritive oral behaviour, min	30.2	37.7	27.3	7.19	0.68	0.08

SEM: standard error of the mean.

NRC. 2001. Nutrient requirements of dairy cattle. 7th rev. ed. Washington (DC): National Academy of Sciences.

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ASABE. 2003. Methods of determining and expressing fineness of feed materials by sieving. Standard No. S319.3. St. Joseph (MI): American Society of Agricultural and Biological Engineers; p. 202–205.

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Data availability statement

The data that support the findings of this study are available from the corresponding author, [F. Hashemzadeh], upon reasonable request.