Dietary zinc requirement of Labeo rohita juveniles fed practical diets

Figures & data

Table 1. Composition of basal practical diet.

Ingredient	Percentage (%)
Soybean meal	30
Corn-gluten	23
Sunflower meal	20
Fishmeal	15
Fish oil	5
Wheat flour	4.5
Vitamin premix^a	1
Zn free mineral mixture	1
Chromic oxide	0.5
Total	100

Notes: Vitamin A 15 M.I.U. Vitamin D3 3 M.I.U. Nicotinic acid 25,000 mg; Vitamin B1 5000 mg Vitamin E 6000 IU Vitamin B2 6000 mg; Vitamin K3 4000 mg Vitamin B6 4000 mg Folic acid 750 mg; Vitamin B12 9000 mg Vitamin C 15,000 mg Calcium pantothenate 10,000 mg.

^aEach Kg of vitamin premix contains.

Table 2. Composition of Zn free mineral mixture.

Salt	mg/g
CaCO3	316
KH2PO4	479
MgSO4.7H2O	153
NaCl	51
CoCl.6H2O	0.0816
AlCl3.6H2O	0.255
CuSO4.5H2O	210.67
FeSO4.H2O	100.67
MnSO4.5H2O	1l16.67

Table 3. Proximate composition of experimental diets.

Experimental Diets	Zn-gluconate Level (mg/kg)	Dry matter (%)	Crude protein (%)	Crude fat (%)	Crude ash (%)	Gross energy (kcal/kg)	Zn (µg/g)
Zn1	0	90.82	34.928	7.085	8.165	3926.875	43.97
Zn2	21	90.4	35.345	7.04	8.6	4000.905	60.44
Zn3	42	90.825	34.899	7.46	8.785	4074.865	80.39
Zn4	63	91.005	35.549	7.35	9.145	4002.54	101.03
Zn5	84	90.895	35.644	7.045	9.495	3958.665	117.13
Zn6	104	91.125	35.0045	6.93	9.7	4009.015	140.99

Table 4. Effect of graded levels of Zn on growth performance of L. rohita juveniles.

Zn-gluconate levels (mg/kg)	0	21	42	63	84	104	p-value
Experimental diets	Zn1	Zn2	Zn3	Zn4	Zn5	Zn6
Final weight (g)	15.03 ± 0.12^d	16.1 ± 0.601^c	17.57 ± 0.05^a	17.37 ± 0.07^a	16.93 ± 0.12^ab	16.44 ± 0.16^bc	.0006***
Absolute weight gain (g)	11.89 ± 0.07^d	12.96 ± 0.608^c	14.39 ± 0.06^a	14.22 ± 0.09^a	13.78 ± 0.106^ab	13.29 ± 0.15^bc	.0007***
Weight gain (%)	378.83 ± 2.64^c	412.1 ± 20.26^b	453.38 ± 3.01^a	451.59 ± 4.94^a	437.61 ± 1.40^ab	421.89 ± 3.04^b	.0010**
Specific growth rate (%)	1.74 ± 0.006^c	1.81 ± 0.04^b	1.90 ± 0.006^a	1.89 ± 0.009^a	1.86 ± 0.002^ab	1.83 ± 0.006^ab	.0010**
FI (g)	18.92 ± 0.24^a	16.97 ± 0.106^b	16.52 ± 0.03^c	16.85 ± 0.07^b	17.15 ± 0.07^b	17.12 ± 0.106^b	.0000***
FCR	1.59 ± 0.01^a	1.31 ± 0.06^b	1.14 ± 0.007^d	1.18 ± 0.002^cd	1.24 ± 0.01^bc	1.28 ± 0.007^b	.0001***
Survival rate (%)	97.22 ± 3.92	100 ± 0	94.44 ± 0	94.44 ± 7.85	100 ± 0	97.22 ± 3.92	.5876 ns

Notes: The data are means of two replicates. The data are presented in means ± standard deviation. Mean values sharing different superscript letters within a row are significantly different (p < .05). FI = feed intake; FCR = feed conversion ratio.

Figure 1. Graphical representation showing the dietary requirement of Zn for L. rohita juveniles.

Table 5. Effect of graded levels of Zn on muscle proximate composition of L. rohita juveniles.

Zn-gluconate levels (mg/kg)	0	21	42	63	84	104	p-value
Experimental diets	Zn1	Zn2	Zn3	Zn4	Zn5	Zn6
Dry matter (g/kg)	239.85 ± 0.54	242.03 ± 0.92	239.7 ± 0.93	239.96 ± 2.10	241.57 ± 1.49	239.51 ± 0.80	.3201 ns
Crude protein (g/kg)	171.49 ± 1.21	170.61 ± 3.20	171.46 ± 2.70	171.005 ± 0.89	171.89 ± 1.20	170.71 ± 1.54	.9808 ns
Crude fat (g/kg)	42 ± 0.46	42.16 ± 1.85	40.5 ± 1.64	39.86 ± 1.28	42.64 ± 0.16	42.08 ± 0.91	.2839 ns
Crude ash (g/kg)	19.18 ± 1.24	20.98 ± 0.49	19.47 ± 2.61	19.02 ± 0.25	20.45 ± 4.63	19.90 ± 0.23	.9346 ns

Notes: The data are means of two replicates. The data are presented in means ± standard deviation. Mean values sharing different superscript letters within a row are significantly different (p < .05).

Table 6. Effect of graded levels of Zn on Zn contents (µg/g) in bones, scales, intestine and faeces of L. rohita juveniles.

Zn-gluconate levels (mg/kg)	0	21	42	63	84	104	p-value
Experimental diets	Zn1	Zn2	Zn3	Zn4	Zn5	Zn6
Bones	136.5 ± 0.33^d	138.58 ± 0.35^c	141.57 ± 1.16^b	146.004 ± 0.13^a	147.51 ± 0.38^a	146.030.23^a	.0000***
Scales	88.56 ± 0.64^d	90.69 ± 0.01^c	94.95 ± 0.103^a	94.89 ± 0.03^a	92.84 ± 0.03^b	90.69 ± 0.07^c	.0000***
Intestine	345.71 ± 2.12^f	352.16 ± 0.68^e	357.07 ± 1.08^d	361.60 ± 1.81^c	369.92 ± 0.55^b	378.17 ± 0.97^a	.0000***
Faeces	35.40 ± 0.63^f	47.1 ± 0.43^e	60.3 ± 0.13^d	86.22 ± 2.11^c	102.65 ± 1.15^b	124.91 ± 1.68^a	.0000***

Notes: The data are means of two replicates. The data are presented in means ± standard deviation. Mean values sharing different superscript letters within a row are significantly different (p < .05).

Figure 2. Effect of graded levels of Zn on Zn absorption of L. rohita juveniles.

Table 7. Effect of graded levels of Zn on TBARS (mg/g protein) contents in kidney and spleen of L. rohita juveniles.

Zn-gluconate levels (mg/kg)	0	21	42	63	84	104	p-value
Experimental diets	Zn1	Zn2	Zn3	Zn4	Zn5	Zn6
Kidney	1.90 ± 0.04^a	1.63 ± 0.04^b	1.36 ± 0.04^c	1.06 ± 0.09^d	1.102 ± 0.04^d	1.43 ± 0.04^c	.0000***
Spleen	1.5 ± 0.14^a	0.90 ± 0.14^b	0.90 ± 0.04^b	0.76 ± 0.04^b	1.46 ± 0.09^a	1.5 ± 0.04^a	.0005***

Notes: The data are means of two replicates. The data are presented in means ± standard deviation. Mean values sharing different superscript letters within a row are significantly different (p < .05). TBARS = Thiobarbituric acid reactive substances.

Table 8. Effect of graded levels of Zn on ALP activity (U/g protein) in kidney and spleen of L. rohita juveniles.

Zn-gluconate levels (mg/kg)	0	21	42	63	84	104	p-value
Experimental diets	Zn1	Zn2	Zn3	Zn4	Zn5	Zn6
Kidney	175.32 ± 1.608^d	183.25 ± 2.23^bc	188.73 ± 2.02^ab	187.69 ± 1.45^ab	190.92 ± 3.11^a	178.96 ± 1.18^cd	.0015**
Spleen	46.92 ± 0.44^c	52.18 ± 2.32^b	57.63 ± 0.98^ab	58.87 ± 0.91^a	56.83 ± 2.29^ab	53.28 ± 1.48^b	.0021**

Notes: The data are means of two replicates. The data are presented in means ± standard deviation. Mean values sharing different superscript letters within a row are significantly different (p < .05). ALP = Alkaline Phosphatase.