The beneficial impacts of dietary phycocyanin supplementation on growing rabbits under high ambient temperature

Figures & data

Table 1. Ingredients and nutrient contents of the basal diet of growing rabbits (% as fed).

Items	Basal diet
Ingredient	%
Maize	20
Soybean meal	20
Wheat bran	16
Berseem hay	30
Barley grain	10
Molasses	2
Limestone	1
NaCl	0.5
Premix*	0.5
Calculated composition, %**
ME, MJ/kg	7.95
Crude protein	17.50
Calcium	0.88
Available phosphorus	0.20

*Each 1 kg of premix (minerals and vitamin mixture) contains vit. A, 20,000 IU; vit. D3, 15,000 IU; vit. E, 8.33 g; vit. K, 0.33 g; vit. B1, 0.33 g; vit. B2, 1.0 g; vit. B6, 0.33 g; vit. B5, 8.33 g; vit. B12, 1.7 mg; pantothenic acid, 3.33 g; biotin, 33 mg; folic acid, 0.83 g; choline chloride, 200 g. **Calculated according to NRC (1977).

ME: Metabolizable Energy.

Figure 1. Calculated temperature-humidity index (THI) throughout the experimental period.

Table 2. Effect of different levels of dietary supplemental phycocyanin on growth performance of growing rabbit PC150(nPC150 PC150=PC150 30/ treatmentPC150) exposed to high ambient temperature PC150(MeanPC150 PC150±PC150 SEMPC150)

Variable	Phycocyanin level^1				Pooled SEM	P-value
	PC0	PC50	PC100	PC150
Initial body weight	795	803.75	808.75	811.25	14.4	0.984
Final body weight	1707.5b	1905a	1887.5ab	1872.5ab	31.7	0.042
Total weight gain	912.5	1101.25	1078.75	1061.25	17.3	0.542
Average daily weight gain PC150(g /dayPC150)	18.62	22.48	22.01	21.66	1.54	0.621
Total feed intake	422.36	448.51	454.09	500.88	12.32	0.322
Daily feed intake PC150(g/dayPC150)	8.62	9.15	9.27	10.22	1.62	0.451
Feed conversion ratio PC150(g feed/g gainPC150)	3.29ab	2.89c	3.12bc	3.48a	0.066	0.002

¹PC0, PC50, PC100 and PC150PC150 PC150=PC150 0, 50, 100 and 150PC150 mg phycocyanin /kg DM diet; respectively.

^{a, b, c} Means within a row without a common superscript letter differ at p PC150< 0.05.

Table 3. Effect of different levels of dietary supplemental phycocyanin on hematological variables of growing rabbit (n = 5/treatment) exposed to high ambient temperature (Mean ± SEM).

Variable	Phycocyanin level*				Pooled SEM	p-value
	PC0	PC50	PC100	PC150
Erythrocytes
RBCs	5.16^b	6.3^a	6.0^a	5.3^b	0.15	<.0001
Platelet	812.3^b	1010.7^a	912.3^a,b	845.3^b	27.94	.023
Haemoglobin	9.97^b	12.1^a	11.4^a	11.3^a	0.26	.002
Haematocrit	37.17	37.3	37.1	37.3	0.07	.818
MCV	96.3	116.3	99.3	97.6	3.29	.077
MCH	32.01	29.4	30.4	30.2	0.40	.133
MCHC	29.01	30.4	29.4	29.3	0.36	.587
Leucocytes
WBCs	7.56^a	5.08^b	4.71^b	4.65^b	0.45	.033
Basophils	0.26	0.3	0.3	0.3	0.01	.855
Eosinophils	0.41	0.4	0.4	0.4	0.01	.146
Neutrophils	12.83	13.3	13.0	13.2	0.29	.957
Lymphocytes	83.58	86.9	85.3	84.5	0.50	.084
Monocytes	1.22	1.0	0.9	1.1	0.04	.050

RBCs: red blood cells (10⁶); MCV: mean corpuscular volume (%); MCH: mean corpuscular haemoglobin (%); MCHC: mean corpuscular haemoglobin concentration; WBCs: white blood cells (10³).

*PC0, PC50, PC100 and PC150 = 0, 50, 100 and 150 mg phycocyanin/kg DM diet; respectively.

^a,bMeans within a row without a common superscript letter differ at p < .05.

Table 4. Effect of different levels of dietary supplemental phycocyanin on kidney and liver functions of growing rabbit (n = 5/treatment) exposed to high ambient temperature (Mean ± SEM).

Variable	Phycocyanin  level*				Pooled SEM	p-value
	PC0	PC50	PC100	PC150
Kidney Function
Creatinine	1.06	1.13	1.09	1.10	0.014	.313
Urea	23.28^a	21.33^a,b	20.92^b	23.10^a	0.374	.015
Liver Function
TB	0.87^a	0.80^a,b	0.79^b	0.86^a,b	0.012	.018
DB	0.30^a	0.24^c	0.25^b,c	0.29^a,b	0.008	.003
TG	122.00	120.67	122.00	122.00	0.940	.961
GGT	45.00^a	35.33^b	36.00^b	42.67^a	1.382	.002

TB: total bilirubin; DB: direct bilirubin; TG: triglycerides; GGT: gamma-glutamyl transferase.

*PC0, PC50, PC100 and PC150 = 0, 50, 100 and 150 mg phycocyanin/kg DM diet; respectively.

^a,b,cMeans within a row without a common superscript letter differ at p < .05.

Table 5. Effect of different levels of dietary supplemental phycocyanin on inflammatory responses and antioxidants indices of growing rabbit (n = 5 rabbits treatment) exposed to high ambient temperature (Mean ± SEM).

Variable	Phycocyanin level*				Pooled SME	p-value
	PC0	PC50	PC100	PC150
Inflammatory responses
IL4	93.67^a	72.33^b	75.00^b	87.67^a	2.782	<.0001
INF-γ	78.33^a	66.33^b	68.67^b	76.33^a	1.593	<.0001
LYZ	1.24^b	1.28^a,b	1.30^a	1.24^b	0.008	.0110
NO	32.57^b	38.94^a	40.25^a	30.10^b	1.336	<.0001
Antioxidants indices
MDA	0.21^a,b	0.19^b,c	0.17^c	0.24^a	0.008	.0010
SOD	0.19	0.16	0.17	0.17	0.005	.1700
GSH	0.19^c	0.32^a	0.28^b	0.19^c	0.018	<.0001
TAC	0.16^b	0.24^a	0.25^a	0.18^b	0.012	<.0001

IL4: interleukin-4; INF-γ: interferonγ; LYZ: lysosome activity; NO: nitric acid; MDA: Malondialdehyde; SOD: superoxide dismutase; GSH: glutathione; TAC: total antioxidant capacity.

*PC0, PC50, PC100 and PC150 = 0, 50, 100 and 150 mg phycocyanin/kg DM diet; respectively.

^a,b,cMeans within a row without a common superscript letter differ at p < .05.

Figure 2. Effect of different levels of dietary supplemental phycocyanin on weekly growth performance of growing rabbit (n = 30/treatment) exposed to high ambient temperature.

Table 6. Effect of different levels of dietary supplemental phycocyanin on caecal microbiota in growing rabbit (n = 5 rabbits/treatment) exposed to high ambient temperature (Mean ± SEM).

	Phycocyanin level				Pooled SEM	p-value
Item*	PC0	PC50	PC100	PC150
Total bacteria	10.64^a	9.26^b	7.9^c	7.8^c	0.376	<.0001
Lactic acid	1.62^c	3.56^a	3.12^a	2.6^b	0.204	<.0001
Escherichia coli	5.19^a	3.70^b	3.43^b	3.40^b	0.227	<.0001
Salmonella	2.91^a	1.74^b	1.48^b,c	1.15^c	0.205	<.0001
Enterococci	6.72^a	5.34^b	4.68^c	4.66^c	0.262	<.0001
Yeasts and moulds	3.68	3.72	3.65	3.65	0.091	.990

*Microbiological count (log CFU/g). PC0, PC50, PC100 and PC150 = 0, 50, 100 and 150 mg phycocyanin/kg DM diet; respectively. Means in the column with different superscript letters are significantly different at p < .05.

NRC. 1977. Nutrient requirements of rabbits: 1977. Washington, DC: National Academies Press.

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