Effects of linseed processing method (ground versus extruded) and dietary crude protein content on performance, digestibility, ruminal fermentation pattern, and rumen protozoa population in growing lambs

Figures & data

Table 1. The ingredients and chemical analysis of experimental diets (% of DM, unless differently shown).

	Treatments^a
	GLS		ELS
	12CP	15CP	12CP	15CP
Ingredients
Alfalfa hay, chopped	30	30	30	30
Wheat straw, chopped	10	10	10	10
Barley grain, grounded	25	25	25	25
Corn grain, grounded	15	13	15	13
Wheat bran	7	4	7	4
Soybean meal	1	6	1	6
Grounded linseed	10	10	0.00	0.00
Extruded linseed	0.00	0.00	10	10
Mineral–vitamin mix^b	1.10	1.10	1.10	1.10
Salt	0.40	0.40	0.40	0.40
Calcium carbonate	0.50	0.50	0.50	0.50
Chemical composition based on %, otherwise stated
Dry matter	90	90	90	90
Crude protein	12.00	15.00	12.00	15.00
Rumen degradable protein	7.95	9.93	8.20	10.18
Rumen undegradable protein	4.05	5.07	3.80	4.82
Organic matter	92.60	92.40	92.80	92.80
Ether extract	5.91	5.73	5.89	5.63
Neutral detergent fibre	36.20	36.50	36.10	36.40
Non-fibre carbohydrate^c	38.70	35.90	39.00	36.60
Metabolisable energy^c, MJ/kg	10.80	10.83	10.78	10.71
Fatty acid profile, %
C14:0	0.53	0.59	0.50	0.55
C16:0	15.77	15.83	15.69	15.72
C16:1	0.84	0.71	0.78	0.69
C18:0	3.41	3.48	3.37	3.33
C18:1; n9	14.16	13.87	14.00	13.96
C18:2; n6	43.73	43.58	43.86	43.97
C18:3; n3	20.01	20.26	20.19	20.31
Other fatty acids	1.55	1.68	1.61	1.47

^aTreatments were: 1) Ground linseed (GLS) with 12% dietary protein content (GLS-12CP); 2) Ground linseed with 15% dietary protein content (GLS-15CP); 3) Extruded linseed (ELS) with 12% dietary protein content (ELS-12CP); 4) Extruded linseed with 15% dietary protein content (ELS-15CP).

^bEach kg of the supplement contained vitamin D (100,000 IU), vitamin A (600,000 IU), vitamin E (3000 IU), calcium (185 g), phosphorus (35 g), magnesium (21 g), sodium (24 g), manganese (3 g), copper (0.8 g), iron (2 g), zinc (4 g), iodine (50 mg), selenium (14 mg), cobalt (29 mg).

^cCalculated based on NRC (2001) equations [non-fibrous carbohydrate (NFC) was calculate as 100 – (CP + NDF + EE + ash).

Table 2. Least square means for performance and nutrient digestibility in lambs fed diets with different linseed processing method (ground vs. extruded) and dietary protein content (12% vs. 15%, DM basis).

	Treatments^a
	GLS		ELS				p-value^b
Item	12CP	15CP	12CP	15CP		SEM	LS		CP	LS × CP
Performance
Initial body weight, kg	24.20	24.40	24.60	24.70		0.67	.58		.79	.84
Final body weight, kg	39.80	41.10	37.20	40.10		0.76	.04		.01	.27
Dry matter intake, g/d	1365	1401	1286	1361		25.30	.02		.03	.46
Metabolisable energy intake, MJ/d	14.72	15.16	13.85	14.55		1.34	.03		.05	.34
Protein intake, g/d	162.30	210.00	155.20	204.30		9.12	.02		.04	.38
Average daily gain, g/d	222^a	237^a	180^b	221^a		8.57	.01		.02	.05
Feed conversion ratio	6.44	6.23	7.68	6.48		0.38	.03		.04	.06
Nutrient digestibility,%
Dry matter	73.78	75.21	71.66	72.98		1.03	.04		.18	.95
Organic matter	77.45	78.03	71.89	73.47		1.69	.03		.49	.78
Crude Protein	67.66	68.97	61.73	65.22		1.51	.01		.15	.72
Neutral detergent fibre	52.81	53.64	51.28	51.92		2.78	.37		.69	.95
Acid detergent fibre	43.68	44.54	42.10	42.51		2.14	.09		.54	.82
Ether extract	81.35	81.19	78.12	78.86		1.77	.08		.84	.76

^aTreatments were: 1) Ground linseed (GLS) with 12% dietary protein content (GLS-12CP); 2) Ground linseed with 15% dietary protein content (GLS-15CP); 3) Extruded linseed (ELS) with 12% dietary protein content (ELS-12CP); 4) Extruded linseed with 15% dietary protein content (ELS-15CP).

SEM = Standard error of means; LS = Linseed; CP = Crude protein.

^bStatistical comparisons: LS = linseed processing method (ground linseed vs. extruded linseed); CP; 12 vs.15% dietary protein content based on the dry matter; LS × CP = interaction of linseed processing method and dietary protein content.

Table 3. Least square means for rumen fermentation profile and protozoa population in lambs fed diets with different linseed processing methods (ground vs. extruded) and dietary protein content (12% vs. 15%, DM basis).

	Treatments^a
	GLS		ELS			p-value^b
Item	12CP	15CP	12CP	15CP	SEM	LS	CP	LS × CP
Rumen fermentation profile
pH	6.36	6.38	6.43	6.48	0.06	.14	.56	.82
Short-chain fatty acids, mmol/L	102.70	103.40	99.20	101.10	1.73	.09	.43	.71
Acetate, mM/100 mM	60.80	61.20	59.70	59.90	0.62	.12	.70	.83
Propionate, mM/100 mM	25.70	25.90	23.80	24.60	0.59	.03	.29	.47
Butyrate, mM/100 mM	10.80	9.50	12.90	11.70	0.47	.01	.02	.85
Acetate: Propionate	2.30	2.30	2.50	2.40	0.08	.13	.57	.48
Branched-chain volatile fatty acids, mM/100 mM	2.70	3.40	3.60	3.80	0.26	.05	.21	.26
NH3–N, mg/dL	13.40	14.70	15.50	16.00	0.58	.02	.09	.71
Protozoa population (×10^3 ml^–1)
Entodinium sp	605.60	617.80	511.30	567.70	47.16	.13	.45	.64
Holotrichs	19.20	21.10	15.90	17.80	2.47	.19	.34	.99
Cellulolytic^c	4.10	4.90	3.30	3.00	0.65	.03	.68	.36
Total	628.90	643.80	530.50	588.40	47.43	.11	.44	.65

^aTreatments were: 1) Ground linseed (GLS) with 12% dietary protein content (GLS-12CP); 2) Ground linseed with 15% dietary protein content (GLS-15CP); 3) Extruded linseed (ELS) with 12% dietary protein content (ELS-12CP); 4) Extruded linseed with 15% dietary protein content (ELS-15CP).

SEM = Standard error of means; LS = Linseed; CP = Crude protein.

^bStatistical comparisons: LS = linseed processing method (ground linseed vs. extruded linseed); CP; 12 vs.15% dietary protein content based on dry matter; LS × CP = interaction of linseed processing method and dietary protein content.

^cThe cellulolytic protozoa family was Epidinium + Eudiplodinium + Polyplastron.

Table 4. Least square means for urinary purine derivatives, microbial protein synthesis, and blood metabolites in lambs fed diets with different linseed processing methods (ground vs. extruded) and dietary protein content (12% vs. 15%, DM basis).

	Treatments^a
	GLS		ELS			p-value^b
Item	12CP	15CP	12CP	15CP	SEM	LS	CP	LS × CP
Urinary purine derivatives and microbial protein synthesis
Allantoin, mmol/d	8.34	8.96	6.14	8.03	0.65	.02	.05	.33
Uric acid, mmol/d	2.67	2.71	2.46	2.41	0.19	.21	.99	.83
Xanthine + hypoxanthine, mmol/d	1.21	1.28	1.03	1.12	0.12	.11	.43	.95
Total PD^c, mmol/d	12.21	12.95	9.64	11.57	0.84	.01	.04	.36
Microbial protein synthesis, g/d	65.70	69.73	51.79	62.13	3.59	.01	.04	.36
Blood metabolites and liver enzymes
Glucose, mg/dl	66.40	67.60	62.40	65.10	1.53	.03	.09	.56
Blood urea nitrogen, mg/dl	18.80	20.90	20.60	21.30	0.70	.04	.08	.29
Cholesterol, mg/dl	60.30	62.20	56.50	57.20	1.82	.02	.47	.73
HDL-cholesterol, mg/dl	37.90	39.30	33.80	35.30	1.64	.04	.41	.99
LDL-cholesterol, mg/dl	22.40	22.90	22.70	21.90	1.16	.74	.95	.60
Triglyceride, mg/dL	25.50	24.70	27.10	26.40	1.01	.09	.55	.84
Total protein, g/dl	5.60	6.00	5.30	5.90	0.34	.23	.06	.81
Aspartate aminotransferase, U/L	104.90	103.50	106.70	111.20	3.46	.21	.65	.34
Alanine aminotransferase, U/L	19.30	20.20	18.10	18.60	1.21	.26	.42	.84

^aTreatments were: 1) Ground linseed (GLS) with 12% dietary protein content (GLS-12CP); 2) Ground linseed with 15% dietary protein content (GLS-15CP); 3) Extruded linseed (ELS) with 12% dietary protein content (ELS-12CP); 4) Extruded linseed with 15% dietary protein content (ELS-15CP).

SEM = Standard error of means; LS = Linseed; CP = Crude protein; PD = purine derivatives; HDL = High density lipoporotein; LDL = Low density lipoprotein; DM = Dry matter.

^bStatistical comparisons: LS = linseed processing method (ground linseed vs. extruded linseed); CP; 12 vs.15% dietary protein content based on dry matter; LS × CP = interaction of linseed processing method and dietary protein content.

^cTotal PD (mmol/d) = allantoin + uric acid + xanthine + hypoxanthine.

NRC. 2001. Nutrient requirements of dairy cattle. 7th revised edition. Washington, DC, USA: National Academy Press,.

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Data availability statement

Data available on request due to privacy/ethical restrictions.