The experiment was conducted at Nogga Farms, located along Secretariat Road, Oju Local Government Area of Benue State, Nigeria. Oju town is located in latitude 6˚51'North and longitude 8˚25'East in South Guinea Savannah Zone of Nigeria. The area has an annual rainfall of 1200 mm to 1500 mm with an average minimum and maximum daily temperature of about 21˚C and 35˚C in the dry season and 16˚C and 37˚C in wet season respectively. The relative humidity ranges from 60% to 80% [13] [14] .

Euphorbia heterophylla plants were sourced from Oju metropolis and nearby communities. The plants were harvested by pulling them from the soil and the leaves detached from the stems. The leaves were washed in clean water and air dried under a shade by spreading them evenly on a mat with regular turning to avoid mould growth; they were milled in a hammer mill fitted with 2 mm sieve before being used to produce Euphorbia heterophylla leaf meal (EHLM). Prior to inclusion in the diet, the EHLM was sub-sampled and analyzed for proximate composition to guide in feed formulation.

The feeding trial conducted for one hundred and eighty (180) day old chicks of Ross 308 strain consisted of six (6) experimental diets tagged: T1, T2, T3, T4, T5 and T6 containing EHLM which replaced soybean meal at 0%, 5%, 10%, 15%, 20% and 25% respectively in starter and finisher diets as contained in Table 1 and Table 2 . Each treatment was replicated three times. The feeding trial lasted 56 days (8 weeks) in a completely randomized design.

The experimental animals were raised in a conventional deep litter poultry house with concrete floor, dwarf walls and zinc coated metal roofing with wire nettings, to enhance adequate ventilation and protection. Birds were given the experimental diets and water ad-libitum. The birds were administered Newcastle

Starter ¹Vitamin/mineral premix (Bio-mix brand) supplied per kilogramme: Vitamin A 450,000 IU, Vitamin D3 9000 IU, Vitamin E 900 IU, Vitamin K 75 mg, Vitamin B12 0.6 mg, Thiamine (B1) 60 mg, Riboflavin (B2) 180 mg, Pyridoxine (B6) 120 mg, Niacin 1200 mg, pantothenic acid 300 mg, folic acid 30 mg, Biotin 2.4 mg, Choline chloride 15 g, Antioxidant 3.75 g, Manganese 2.88 g, Zinc 1.8 g, Iron 0.72 g, Copper 0.18 g, Iodine 0.042 g, Selenium 7.2 mg, Cobalt 7.2 mg. EHLM—Euphorbia heterophylla leaf meal; SBM—Soya bean meal.

^ab*Means with different superscripts are significantly different (P < 0.05). PVC = Packed Cell Volume. RBC = Red Blood Cells; WBC = White Blood Cells; Hb = Haemoglobin; MCV = Mean Corpuscular Volume, MCH = Mean Corpuscular Haemoglobin; MCHC = Mean Corpuscular Haemoglobin Concentration; S.E.M = Standard Error of the Mean; EHLM = Euphorbia heterophylla leaf meal; LS = Level of Significance; S = Sifnigicant; NS = Not Significant.

vaccine (lasota) at the 4^th and 24^th day, while Gumboro vaccine was given at the 10^th and 16^th day. Multivitamin, mineral and glucose were administered in drinking water on arrival. Anti-coccidial drug (Pentacox^®) and antibiotic (Ciprofloxacilin^®) were given to the birds in drinking water in alternate week while anti-stress was administered when necessary.

Blood samples (5 mL) were collected twice between 8:30 am and 9:30 am by cutting the jugular vein of one bird per treatment replicate in sterile bottle containing about 2 mg of ethylene diamine tetra-acetic acid (EDTA) packed in ice pack to maintain cool and stable temperature and taken to laboratory to for analysis of red blood cells (RBC), White blood cells (WBC), packed cell volume (PCV), haemoglobin concentration (Hb) and mean corpuscular haemoglobin concentration (MCHC) using the standard procedures by [15] . Another 3 ml of blood sample was collected in an anticoagulants free tube and taken to laboratory for analysis of blood total protein, albumin, creatine using sigma kits. Glucose was analyzed according to [16] and cholesterol according to the procedure of [17] . Liver enzymes (AST, ALT and ALP) were analyzed as outlined by [18] .

White blood cells differentials (lymphocytes, hererophills, monocytes, eosinophils and basophils) were also determined via slide reading under microscope after blood smear and staining.

The data obtained were subjected to one-way analysis of variance (ANOVA) in a completely randomized design using the procedure outlined in [19] . Where significant difference between treatment means occurred, they were separated using the Fisher’s method described in Minitab (2014). Fit Regression Model contained in [19] was used for the analysis. Formula – Y = A + B + C + D + E + F + G.

The haematological parameters of finisher broiler chicken ( Table 2 ) showed packed cell volume (PCV), red blood cells (RBC), haemoglobin concentration (Hb) were significantly (P < 0.05) influenced by the levels of EHLM inclusion with the highest values in the control (PCV = 45.67%, RBC = 2.30 × 10 U/L and Hb = 15.23 g d/L). Treatments 3, 4, 5 and 6 have similar values. The values ranged from 33.00 (T2) - 45.67% = PCV; 1.90 (T2) - 2.30 (10¹²/L) = RBC and 11.00 (T2) - 15.23 g/dL = Hb. Mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) were statistically similar with those of T1 (182.00 fl = MCV and 66.00 pg = MCH) which were also similar with the values of T4, T5, and T6. The values ranged from 173.53 (T2) - 206.50 fl for MCV and 58.07 (T2) - 68.67 pg for MCH. Lymphocytes, heterophils, and eosinophils varied significantly (P < 0.05) with range values of 44.33% - 50.67%, 45.67% - 50.67% and 1.00% - 4.00% respectively which were similar with the control. The white blood cell count (WBC), mean corpuscular haemoglobin concentration (MCH), monocytes and basophils did not show significant difference (P < 0.05).

Heamatology is available in assessing the physiological responses of chicken [2] [20] . PCV and Hb are two parameters of high significance in determining health status of broiler chickens. The parameters were affected by levels of EHLM inclusion but both values were within the normal range (PCV = 35.9% - 41.0%; 25.20% - 45.20% and 11.60 - 13.68 g/dL; 10.02 - 15.1 g/dL) described for healthy birds by [21] - [23] respectively. The PCV and Hb values in the present study are similar with values of 25% - 45% and 10.25 - 15.87 g/dL reported by [24] [25] for broiler in Nigeria and commercial Ross 308 strain respectively. The value of RBC is within the normal ranges of 1.58 - 3.8 (×10¹²/L) as reported by [22] which was also in agreement with the value of 2.00 - 3.00 (×10¹²/L) described by [26] [27] for broiler chicken in Nigeria. The similarity in the values of RBC in T1, T4 and T5, suggested that 15% and 20% of EHLM levels had no adverse effect on the blood profile. The increase in PCV in this study correlated with increase in RBC hence the diets with highest RBC values (T1, T4 and T5) had high PCV while the T2 and T6 had the lowest RBC and PCV. This agreed with [28] who reported that PCV rose while RBC increased. The high value of PCV in T3 (41.33%) with low RBC - 2.0 (×10¹²/L) was a chance effect. The significantly (P < 0.05) higher levels of PCV, RBC and Hb in T1 could be attributed to the higher level of protein in the diet and level of protein intake by the birds. This observation was consistent with the findings of [22] [29] . Significantly (P < 0.05) higher Hb value in T1 may be attributed to adequacy of critical nutrients such as iron, copper, vitamins and amino acids [41] . Though, there were significant (P < 0.05) effect in the values of PCV, RBC and Hb, with the highest value in the control, the values across the treatment groups fell within the normal range suggesting that feeding EHLM did not result in disturbances to erythrocyte indices that could adversely impact the health of broiler birds.

Though, the mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values showed significant (P < 0.05) effect, the value obtained in this study were similar with control except in T3 which also had the highest values (206.50 fl) of MCV and 88.67 pg of MCH). This high value of MCV and MCH in T3 which has low RBC 2.0 (×10¹²/L) could be attributed to mild haemolytic effect of saponin in the blood of the birds though the RBC level was within the normal level (1.58 - 3.80 (×10¹²/L) reported by [22] . However, since the MCV and MCH in 15%, 20% and 25% EHLM were statistically similar to the control (0% EHLM), the higher value in T3 (10% EHLM) could not be as a result of the effect of diet but strain effect. This suggests that the significant variation in MCV and MCH does not have negative impact on chickens. This agreed with the findings [25] who observed significant (P < 0.05) high values of MCV and MCH in Ross 308 broiler strain which was also used for this study but reported no negative impact on the chickens. The researcher reported a lower and upper limit values of 77.00 - 88.40 fl and 159.98 - 187.50 fl for MCV and 26.00 - 28.83 pg and 54.36 - 63.13 pg for MCH as normal values for Ross 308 broiler strain. More so, the value of MCV and MCH in this study is in agreement with normal reference range of 89 - 203 fl and 39 - 61 pg reported by [30] for MCV and MCH respectively and similar to the values of 175.30 fl and 55.80 pg observed for MCV and MCH by [31] who fed broiler chickens with graded levels of Artenia urmania powder. The report of [25] who observed that the variation in the values of MCV and MCH could be the consequence of the effect of the parameters such as age, sex, weight, type of diet, strain and climate on chickens, suggested that the significant (P < 0.05) difference in the value of MCV and MCH in this study may not negatively affect the birds as RBC, WBC, PVC, Hb and MCHC values were normal. The blood parameters with greater values observed in this study could also be a consequence of wide range of ambient temperature. This is consistent with the findings of [27] . Mean corpuscular haemoglobin concentration (MCHC) values were not affected (P < 0.05) by the diets. Values were within the normal range of 32.41 - 33 - 37 g/dL reported by [21] . The normal values of MCV, MCH and MCHC in this study indicated an intact immune system. This agreed with the report of [32] . The higher WBC values with increasing EHLM inclusion levels were reflected in significantly (P < 0.05) higher lymphocytes, heterophils and eosinophils differentials which suggested the potential of EHLM to stimulate immune response. This agreed with [10] who reported that immune-modulatory properties of quercetin (flavonoid) saponin and terpenes have effect on hormonal and cellular immunity. White blood cells (RBC) also called leucocytes are important medications of immune response in living organisms, and high WBC count have generally been regarded as efficient immune response [33] . According to [34] , increase in WBC differentials in the blood indicated enhanced immunological well-being of the body. The WBC count in T2, T3, T4, T5 and T6 which were similar with the control which had the lowest value suggested that the test ingredient has the potential to stimulate immune production to protect birds against diseases. The values obtained for WBC, lymphocytes, heterophils and eosinophil were within the normal ranges of 2.2 - 7.5 (×10 g/L) and 1.0 - 9.5 (×10³ u/L), 45% - 70%; 20% - 50% and 1% - 4% reported by [22] . The monocytes and basophils values showed no diet effect. The values agreed with the normal reference levels of 2% - 8% and 0% reported by [21] for broiler chickens in Nigeria.

The serum biochemical indices of finisher broiler chickens ( Table 3 ) showed significant (P < 0.05) difference for serum total protein, Albumin and glucose. Serum total protein and albumin values were highest in T5 (7.63 g/dL) and T6 (2.30 g/dL) respectively. The values across the treatment groups were similar with the control apart from T5 that had the highest value. Serum protein had values range from 5.20 - 7.63 g/dL and 2.30 - 3.80 g/dL for albumin. Though the value of glucose was significantly (P < 0.05) affected by EHLM inclusion levels, the values across treatment groups were similar with the control (169.73 g/dL) apart from T6 (231.33 g/dL) and T5 (215.60 g/dL) and T2 (110.07 g/dL) which had the highest and least values respectively. Aspartate amino transferase (AST), Alanine amino transferase (ALT) and Alkaline phosphatase (ALP) showed significant (P < 0.05) diet effect on the birds. However, the values of 103.83 (T3) - 119.37 u/L (T4) = AST; 39.97 (T6) - 43.40 u/L (T4) for ALT and 46.23 (T2) - 61.30 u/L (T4) for ALP. Globulin, Albumin/globulin ratio, serum cholesterol and creatinine were not affected by the diet. However, cholesterol value decreased with increasing EHLM inclusion levels.

The use of biochemical indices as a pointer to conditions that may not be readily noticed by performance indices cannot be over-emphasized. Plane of nutrition is known to affect these values [35] . The observed significantly (P < 0.05) higher values of total serum protein (TSP) in this study which were similar to the control could be attributed to the significantly (P < 0.05) higher liver size and weight which results in the increased activities of the liver. This was activated by the effect of increased concentration of n-3 PUFA such as alpha-linolenic acids, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) in the liver of chickens fed EHLM. This resulted in increased activity of the liver, thus, the liver increased synthesis of serum protein (TSP) concentration in the blood. Furthermore, the intensity of the building of proteins into the tissues may significantly influence the concentration of proteins in the blood as well as their compositions as reported by [8] [36] . The values of serum protein in this study (5.20 - 7.63 g/dL) were higher than the normal reference values (3.0 - 4.9 g/dL and 3.55 - 4.96 g/dL) established by [22] [37] respectively but similar to the value of 4.96 - 6.40 g/dL and 5.49 - 6.25 g/dL reported by [38] [39] for Ross 308 broiler strain respectively. The high serum protein values in this study

^abc*Means with different superscripts are significantly different (P < 0.05). AST = Aspartate Amino Transferase; ALT = Alanine Amino Transferase; ALP = Alkaline Phosphatase; S.E.M = Standard Error of the Mean; EHLM = Euphorbia heterophylla leaf meal; LS = Level of Significance; S = Sifnigicant; NS = Not Significant.

agreed with [40] who reported that high serum protein was an indication of healthy liver because severe liver damage or prolonged protein deficiency usually leads to reduced plasma protein synthesis. The similarity in the values of serum protein among the dietary treatments with the control inferred that the high serum protein could be attributed to high protein and lipid profiles of EHLM and not any abnormality. The higher level of albumin correlated with the high value of serum protein which indicated higher clotting ability of the blood and enhance prevention of haemorrhages and this agreed with [35] . The non-significant (P < 0.05) variation in the globulin and albumin/globulin ratio could be due to the adequate protein in all the treatment diets. The globulin level was higher in T2, T4, T5 and T6 than in the control (2.40 g/dL) while the albumin/globulin ratio was higher in the control (1.70 g/dL) compared to other dietary treatments which inferred that EHLM has the greater ability to stimulate immunity to fight infection. This is in agreement with the findings of [35] [41] who reported that high levels of globulin and low albumin/globulin ratio was indicative of high immune production and ability to fight infections by birds. The values of albumin, globulin and albumin/globulin ratio were within the normal range of 2.43 - 3.86 g/dL; 2.0 - 3.5 g/dL and 0.75 - 1.53 g/dL established by [21] . The glucose values (110.07 - 231.33 mg/dL) in this study is similar to the normal reference value of 174 - 239 mg/dL reported by [37] [42] but lower than the values of 200 - 500 mg/dL established by [38] [43] except in treatments 6, 5 and 3. The low level of glucose obtained in this study especially in T2 (110.07 g/dL) could be attributed to low level of metabolizable energy in SBM (2420 (Kcal/kg) and EHLM (2339.79 (Kcal/kg) and low amount of fat and oil in EHLM. The serum cholesterol in this study was suppressed as the dietary EHLM increased. This is advantageous in the production of lean broiler carcass since fat is distasteful to the consumers of poultry meat because of incidence of cholesterol-related diseases [12] [44] . The cholesterol lowering effect of increasing CF as EHLM levels increased in the diets could be linked to the binding action of soluble fibre and lignin with the bile acids for excretion [12] . The reduction in cholesterol in this study is principally attributed to increased proportion of total polyunsaturated fatty acids (PUFA), n-3 PUFA, PUFA/SFA ratio and robust decrease in C18:2 n-6/C18:3 n-3 and n-6/n-3 ratios which regulates cholesterol levels in the muscles, plasma and adipose tissues of birds fed EHLM diets. This observation was consistent with the findings of [45] . Values (102.73 - 110.57 mg/dL) of the present study are within the normal range of 87 - 192 mg/dL reported by [37] but lower than the values of 179.50 - 181.50 mg/dL reported by [38] for Ross 308 broiler strain. This agrees with [46] who reported significant reduction of 18% in egg York cholesterol of laying hen fed E. heterophylla diet. The lowering effect of cholesterol in chickens is advantageous in improving heart and general health of the birds which can be attributed to production of lean broiler carcass. This agrees with the findings of [8] [10] [11] [44] who reported that the lowering effects of cholesterol are positively correlated with low fat deposition in adipose tissues, visceral organs and joints resulting in improved carcass and bone development and growth; production of lean carcass and improved meat quality of chickens.

Alteration in the activities of serum enzymes, such as Aspartate aminotransferase (AST), Alanine aminotransferase (ALT) and Alkaline phosphatase (ALP) are often utilized as markers of toxicity for the assessment of biochemical and physiological health of vital organs and tissues, such as liver and heart [47] . It is established that damage to cellular membrane in tissues where these enzymes are normally localized results in their leakage into bloodstream giving an index of cellular integrity [47] the results of this study showed that EHLM diets have significant (P < 0.05) effect on the levels of AST, ALT and ALP. The values are similar with the control (0% EHLM) which fall within the normal reference range of 70 - 220 (u/L); 7 - 56 (u/L) and 40 - 130 (u/L) reported by [37] respectively. The values of the liver enzymes in this study may be positively influenced by the anti-inflammatory activities of the phytochemicals, flavonoids and terpenes in EHLM which maintained the integrity and improved the oxidative status of the liver. This observation was consistent with the findings of [48] who reported flavonoids and terpenoids suppressed the metabolism of inflammatory prostaglandins. Flavonoids and terpenes act by over expressing anti-oxidant enzymes which regulated the inflammatory process, hence prevented damages to the liver and regulating its functional activities [49] . Creatinine values were not significantly (P > 0.05) affected by the EHLM diets which indicated that there was no obvious muscular wastage because of the protein adequacy of the diets. This trend supported the report of [41] . Values from this study (0.59 - 1.17 mg/dL) are within the normal reference range of 0.5 - 1.20 mg/dL reported by [37] . The normal values of creatinine in this study might be influenced by the inhibitory activity of saponin in EHLM on microbial urease enzymes which resulted in decreased production of intestinal ammonia, enhanced the health, integrity and function of kidney. Intestinal ammonia is considered as an important health stress to the kidney [45] .

The result of the growth performance of starter and finisher broiler chickens fed graded levels of spurge weed (Euphorbia heterophylla) Leaf Meal (EHLM) indicated that the experimental diets improved significantly (P < 0.05) the growth of broiler chickens. The average weight gain (AWG) = 32.04 g (T2) to 34.06 g (T3) for starter chick which compared with the control 33.94 g) was affected (P < 0.05) by the diets. However, the AWG for finisher broiler chickens with values ranging from 45.13 g (T5) - 48.28 g (T2) which are similar with control (46.73 g) had diet effect (P > 0.05). The similarity in the values among treatment groups infers that EHLM supported the AWG of broiler chicken. This suggests that feeding EHLM to broiler at graded levels improved performance which is in agreement with [8] .