Effects of different levels of date pits on performance, carcass characteristics and blood parameters of broiler chickens

Abstract

The effect of date pits (DP) in diet of broiler chickens on performance, carcass characteristics and blood parameters was studied. A total of 192 day-old commercial broiler chickens were assigned randomly to four experimental diets containing 0, 10, 20, and 30% of DP kg⁻¹ dry matter. All diets were isonitrogenous and isocaloric, and formulated according to nutrient requirements of poultry. The birds and feed of each treatment were weighted weekly. At 6 weeks of age, bleeding from cardiac puncture performed for serum biochemical analyses. DP significantly decreased final weight, average daily gain and feed consumption (p<0.05). Additionally 20 and 30% of date fibre caused a significant increase in the feed conversion ratio. DP caused a significant decrease in thigh and increase in heart weight, as percent of dressed weight, but had no significant effect on dressed weight and kitchen carcass weight, and percentage of breast, gizzard and liver. However, there was significant difference (p<0.05) in heart and thigh percentage between treatments. The diets had no significant effect on blood parameters including cholesterol, triglycerides, high density lipoprotein, low density lipoprotein and very low density lipoprotein (p>0.05). Blood glucose of birds fed diet containing 20% DP was significantly more than control diet (p< 0.05), but there was no significant difference with diet containing 30% DP (p>0.05). DP could provide a cheap source of feed to birds and using 10% had no negative effects on performance, carcass characteristics and blood parameters.

Keywords:

• date pits
• broiler chickens
• final weight
• average daily gain

1. Introduction

The limited supply of good quality raw materials such as soybean meal, maize and cotton seed meal for the poultry feed industry has resulted in a continuous increase in the cost of production, and thereby causing a phenomenal rise in the unit cost of products (Laudadio and Tufarelli 2010). Thus, these products have become too expensive for the majority of the population in different regions (Tewe, 2003; Esonu et al. 2003). The date seeds are considered a waste by-product of date during use of date for various purposes such as confectionery, prepare date syrup and so on. At present, seeds are used mainly as animal feeds in the cattle, sheep, camel and poultry diets. World production of dates reached 6.9 million tons in 2004, from these approximately 863,000 tones of date seeds are produced in Iran (FAO 2007). Date pits (DP) (grinded stones, kernels or seeds of date) form 6 to 12% of the date fruit depending on variety and quality grade. DP has some advantage, as produced in large quantities in Iran, is cheap and high in energy content. The chemical compositions of DP include 3.1–7.1% moisture, 2.3–6.4% protein, 5.0–13.2% fat, 0.9–1.8% ash and 22.5–80.2% dietary fibre. Also, seeds contain high levels of phenolics (3102–4430 mg Gallic acid equivalents/100 g), antioxidants (580–929 µm trolox equivalents/g) and dietary fibre (78–80%; Al-Farsi et al. 2007), together with 12.53 MJ metabolisable energy (Al-Hiti 1978).

A study by Vandepopuliere et al. (1995) showed that untreated DP from 5 to 27% could be included in broiler diets to support growth performance. Kamel et al. (1981) fed DP to broiler chickens at levels of 5–47% as a replacement for corn and reported that the highest level depressed weight gain and feed efficiency. When they were fed dates meal substituting for corn at 0, 5 and 10% of diets, broiler weight gain and feed conversion ratio (FCR) improved with increasing level. However, Jumah et al. (1973) found that diets containing graded levels (0, 5 and 15%) of DP caused a proportional, gradual reduction in broiler weight gain compared with the control diet. Substitution of high levels (12.5 or 15%) of dietary corn with palm kernel cake (PKC) has been associated with increased feed intake and lower efficiency of feed utilisation in broiler chickens (Osei and Amo 1987). The objective of the present study was to assess the effect of different levels of untreated DP (the mixed varieties of Khuzestan province DP species) in broiler rations on growth performance of broiler chickens and carcass characterises.

2. Materials and methods

2.1. Birds and sampling

The study was conducted in two phases; starter (0–21 days) and grower (21–42 days). Four diets were tested during this study. Diets contained 0, 10, 20 and 30% of the mixed varieties of Khuzestan, tropical province of Iran, dates pits (kg⁻¹ DM), and chemical compositions of DP (DM, Ash, fat and CF; AOAC 1990) are shown in Table 1. There was an attempt to make the diets isocaloric or isonitrogenous. The levels of other ingredients remained constant. The composition of the starter and finisher diets is shown in Table 2.

Table 1. Chemical composition of date pits (%).

	Nutrients
References	DM	CP	CF	Fat	Ash	Ca	p
This experiment	91.76	6.27	16.42	9.57	1.312	0.865	0.097
Kamel et al. (1981)	92.2	5.2	16.2	8.6	1.1	0.57	0.31
Siew et al. (1995)	–	6.5	22	10.4	1.1	0.49	0.12
DM, Dry matter; CP, crude protein; CF, crude fibre.

Table 2. The composition of experimental diets.

	Starter				Grower
	Diet 1control	Diet 2 (10% DP)	Diet 3 (20% DP)	Diet 4 (30% DP)	Diet 1 control	Diet 2 (10% DP)	Diet 3 (20% DP)	Diet 4 (30% DP)
Ingredient
Corn	59.00	49.00	39.00	29.00	63.00	53.00	43.00	33.00
Date pits	0.00	10.00	20.00	30.00	0.00	10.00	20.00	30.00
Soybean Meal-44%	32.03	32.70	30.91	30.86	27.79	26.40	24.50	22.50
Fish meal	3.00	3.00	4.70	5.20	2.50	3.92	5.70	7.45
Oil	1.81	2.03	2.40	2.66	3.25	3.82	4.42	5.03
DCP	1.50	1.20	0.90	0.35	0.90	0.50	0.10	0.00
Oyster	1.50	1.20	1.20	1.20	1.55	1.50	1.45	1.25
Vit. & Min. Premix	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50
Common salt	0.40	0.35	0.3	0.22	0.32	0.30	0.28	0.16
DL-Methionine	0.2	0.00	0.08	0.00	0.1	0.06	0.05	0.02
L-Lysine	0.07	0.02	0.01	0.00	0.09	0.00	0.00	0.00
Chemical composition
ME (Kcal/kg)	2950	2950	2950	2950	3100	3100	3100	3100
Protein (%)	21.20	21.20	21.20	21.20	19.37	19.37	19.37	19.37
Fibre (%)	3.66	5.29	6.76	8.34	3.43	4.93	6.39	7.85
Calcium (%)	1.10	0.96	0.98	0.91	0.96	0.94	0.92	0.91
p (%)	0.50	0.49	0.50	0.45	0.37	0.36	0.36	0.42
Lysine (%)	1.26	1.24	1.27	1.2	1.14	1.11	1.14	1.17
Met + Cys (%)	0.91	0.69	0.76	0.66	0.76	0.70	0.68	0.64
DCP, di calcium phosphate; Vit. & Min., vitamin and mineral; ME, metabolisable energy.

One hundred and ninety two Ross 308 strain male and female broiler type chickens were used for the study. At one day of age, the chickens were divided into 16 similar groups with 12 birds per each group. Four groups were used as replicates of one treatment. The average chicken weight was 45 g. The birds were brooded conventionally in a deep litter system from day-old to 6 weeks of age. Feed and water were given ad libitum. Feed intake and weight gain were recorded weekly.

At the end of 42 day old, two birds from replicate were randomly selected and humanely killed using CO₂ asphyxiation, defeathered and their dressed weights recorded (Raj et al. 1997). They were quickly split open, the organs removed and weighed, and then the eviscerated weights of the birds were recorded (Kabir et al. 2004). When the chickens reached 6 weeks of age, the feeding trial was terminated and 24 broilers from each treatment group (6 chicks for each replicate) were randomly selected and bleeding from cardiac puncture performed for plasma biochemical analyses. Plasma samples were analysed for total cholesterol, glucose, triglyceride, high density lipoprotein (HDL), low density lipoprotein (LDL) and very low density lipoprotein (VLDL) concentrations by diagnostic kits (Pars Azmon Co., Iran) using spectrophotometer.

2.2. Statistical analyses

Data were analysed using the general linear models (GLM) procedure of SAS (2001); SAS Inst. Inc., Cary, NC). Duncan's multiple range test was used to compare treatment means at p<0.05.

3. Results

The effects of substituting maize with DP on performance of growing broiler chickens are shown in Table 3. During the starter phase (0–21 days), body weight gain for the treatments were significantly different (p<0.05). Birds fed diet 1 (control) had the highest average daily gain (ADG) (26.462 g/day) while birds fed diets 4 had lowest ADG. However, there was no significant difference (p>0.05) between birds fed diet 2 compared with control. There was no significant difference (p>0.05) in feed intake between diets. Nevertheless, birds fed diet 4 (30% DP) had lower feed intake than other diets.

Table 3. Effects of data pits on performance of broiler starter and finisher chickens.

	Dietary treatments
Performance parameter	Diet 1 (Control)	Diet 2 (10% DP)	Diet 3 (20% DP)	Diet 4 (30% DP)	SEM
Starter phase
Weight gain (g)	555.7^a	505^ab	465.15^b	381.09^c	20.69
ADG (g/day)	26.462^a	24.048^ab	22.15^b	18.147^c	0.98
Feed intake (g)	1011.57^a	1029^a	1044.58^a	966.61^a	14.13
ADFI (g/day)	48.17^a	49^a	49.74^a	46.02^a	0.64
FCR	1.74^c	1.91^c	2.10^b	2.39^a	0.076
Grower phase
Weight gain (g)	1486.3^a	1268.33^ab	1092.41^bc	954.21^c	66.80
ADG (g/day)	70.776^a	60.397^ab	52.019^bc	45.438^c	3.18
Feed intake (g)	2883.2^a	2831.7^a	2726.7^a	2400.8^b	13.14
ADFI (g/day)	137.29^a	134.84^a	129.84^a	114.324^b	3.30
FCR	2.04^c	2.30^bc	2.64^ab	2.71^a	0.093
ADFI, average daily feed intake; ADG, average daily gain; FCR, feed conversion ratio; SEM, standard error of means.Means within a row with different superscript letters are significantly different (p< 0.05).

During the starter phase, FCR of treatments was significantly different (p>0.05). The control group had better FCR than other treatments; however, there was no significant difference (p>0.05) between control and diet 2 (10% DP) but difference between control and diets 3 and 4 was significant (p<0.05).

During the grower phase, body weight gain of diet 4 was significantly different (p<0.05) in comparison to control diet. The control diet had the highest ADG (70.77 g/day), which was significantly different from diet 4 (30% DP) (p<0.05). Birds on diet 4 had lowest feed intake (p<0.05). In this phase, control diet had the best FCR (p<0.05).

The effect of different levels of DP (0, 10, 20, and 30%) on broiler growth performance in whole of experiment is shown in Table 4. The results indicated final body weight was significantly lower when DP was included in the diet. There were no significant differences (p>0.05) in feed intake between control diet with diets 2 (10% DP) and 3 (20% DP), but there was significant difference (p>0.05) between control and birds fed diet 4 (30% DP).

Table 4. Effects of date pits on performance of broiler chickens (whole period).

	Dietary treatments
Performance parameter	Diet 1 (Control)	Diet 2 (10% DP)	Diet 3 (20% DP)	Diet 4 (30% DP)	SEM
Initial body weight (g)	45	45	45	45	–
Final body weight (g)	2087^a	1818.3^b	1602.6^bc	1380.3^c	85.62
ADG (g/day)	48.16^a	42.22^b	37.08^bc	31.79^c	75.60
Feed intake (g)	3894.8^a	3860.7^a	3771.3^a	3367.4^b	2.03
ADFI (g)	92.73^a	91.92^a	89.79^a	80.17^b	79.60
FCR	1.89^b	2.11^b	2.37^a	2.55^a	1.89
ADFI, Average daily feed intake; ADG, average daily gain; FCR, feed conversion ratio; SEM, standard error of means. Means within a row with different superscript letters are significantly different (p < 0.05).

FCR was minimum amount in control diet and addition of DP caused an increase in FCR.

The carcass characteristics of broilers fed different diets are presented in Table 5. Inclusion of 10, 20 or 30% of DP in broiler diets had no significant effect on dressed weight, kitchen carcass, breast muscle, gizzard and liver percentage (p>0.05) but had effect on heart and thigh percentage (p<0.05).

Table 5. Carcass characteristics of birds on experimental diets (percentage of dressed weight).

	Dietary treatments
Parameter	Diet 1 (Control)	Diet 2 (10% DP)	Diet 3 (20% DP)	Diet 4 (30% DP)	SEM
Dressed weight (% LW)	91.72^a	91.88^a	89.46^a	89.42^a	1.29
Kitchen carcass weight (% DW)	81.63^a	78.74^a	75.35^a	71.33^a	1.76
Thigh (% DW)	34.25^a	33.30^ab	35.24^a	30.71^b	0.65
Breast (% DW)	25.39^a	23.20^a	23.46^a	21.99^a	0.60
Back (% DW)	21.98^a	22.23^a	16.64^a	18.62^a	0.75
Gizzard (% DW)	3.89^a	4.68^a	4.40^a	4.61^a	0.17
Liver (% DW)	2.62^a	7.30^a	3.08^a	3.00^a	0.10
Heart (% DW)	0.62^b	0.73^ab	0.74^ab	0.97^a	0.05
LW, live weight; DW, dressed weight; SEM, standard error of means.Means within a row with different superscript letters are significantly different (p< 0.05).

The birds fed diet containing 20% DP had the highest thigh percentage, which had no significant different with control diet and diet containing 10% DP. The birds fed 30% DP had the lowest thigh percentage, which decreased by increasing the amount of DP in diet (p<0.05). Heart weight increased as amount of DP increased (p<0.05).

The effects of DP on blood parameters of broiler chicken are shown in Table 6. The experimental diets had no significant effect on blood cholesterol, triglycerides, HDL, LDL and VLDL (p>0.05). Blood glucose of birds fed diet containing 20% DP per kilogram DM of diet was significantly more than control diet (p<0.05), but there was no significant difference with diet containing 30% DP (p>0.05), totally, blood glucose was lower in the control group compared with other treatments.

Table 6. The Effects of date pits as feed ingredient of broiler chickens on blood parameters of broiler chickens.

	Diet (% DP/kg DM of diets)
Parameter	Diet 1 (control)	Diet 2 (10% DP)	Diet 3 (20% DP)	Diet 4 (30% DP)	SEM
Glucose (mg/dl)	154.38^c	206.10^bc	275.01^a	255.11^ab	14.05
Cholesterol (mg/dl)	100.89^a	162.94^a	151.89^a	113.18^a	12.71
Triglycerides (mg/dl)	29.76^a	47.34^a	58.28^a	38.58^a	7.19
HDL (mg/dl)	64.92^a	68.75^a	89.62^a	81.78^a	11.76
LDL (mg/dl)	30.02^a	84.72^a	50.61^a	23.68^a	9.86
VLDL (mg/dl)	5.95^a	9.46^a	11.65^a	7.71	6.92
HDL, hay density lipoprotein; LDL, low density lipoprotein; VLDL, very low density lipoprotein; SEM, standard error of means. Means within a row with different superscript letters are significantly different (p < 0.05).

4. Discussion

The results of feeding broiler chickens by starter diet containing 10% DP (diet 2) on growth performance were almost similar to those obtained by Hussein et al. (1998b) who found that body weight gain and FCR of broiler chickens at four weeks of age were not significantly different by the control diet. The observations of Gualtieri and Rapaccini (1990) were similar to the present study, where they stated that using 10% DP in broiler starter diets produced growth performance similar to that gained from a corn–soybean diet. In contrast, it was reported by Jumah et al. (1973) that adding DP to broiler diets caused a reduction in body weight gain compared with the control diet. Kamel et al. (1981) and Hussein et al. (1998a) fed broiler chickens by diets containing 5–15 and 8% DP, and they concluded that addition of DP to broiler rations gave similar results regarding the efficiency of feed utilisation as the control diet. These agreed with the results of the represent study.

Birds fed diet 4 (30% DP) had the lower body weight gain than control group. This could be due to presence of the high fibre in DP and its gritty nature, which reduce digestibility and possibly the availability of nutrients especially amino acids (Yeong 1983; Onwudike 1986). The fibre in DP, according to Babatunde et al. (1975), has lingocellulosic structure; therefore, reducing digestive enzyme action on DP protein and availability of the protein.

The results of feeding broiler chickens with grower diets containing 10% DP (diet 2) on growth performance were almost similar to those obtained by Hussein et al. (1998a) who reported that the inclusion of 10% acid-treated or untreated DP in broiler finisher diets supported and enhanced chickens body weight gain and FCR similarly to those fed the control diet at the end of 6 weeks of age. Also, Gualtieri and Rapaccini (1990) fed chickens by a grower diet containing 10% DP during the finishing period and reported that the inclusion of DP in broiler diets was suitable for supporting growth performance similar to those in the control group. The findings of Hussein et al. (1998a) and Gualtieri and Rapaccini (1990) were in agreement with the results obtained in the present study, since the inclusion of 10% DP in the finisher rations was suitable to support chickens growth performance as well as in the control group.

The results of present study (Table 3) indicated that weight gain was the lowest when 30% DP were added to diet. The results were similar to the result of Ezieshi and Olomu (2008) who found that body weight gain of broiler chickens at finishing period was significantly lower than control when palm kernel meal (PKM), a pure homogenous processed material produced under high temperatures required for the extraction of palm kernel oil) was included in the diet.

Final body weight was significantly low when DP used in diets. The birds fed diet containing DP had lower final weight than control group. This could be due to the high fibre level of DP and its gritty nature, which reduce digestibility and possibly the availability of nutrients especially amino acids (Yeong 1983; Onwudike 1986). According to Babatunde et al. (1975), the structure of DP is fibrous, and therefore may reduce digestive enzyme action on DP protein and availability of the protein. In agreement with present study, Jumah et al. (1973) found that adding DP to broiler diets observed a reduction in body weight gain compared with the control diet (0% DP). Garcia et al. (1999) reported that body weight gain decreased as the levels of palm kernel meal increased to 40% of diet. Also, the results of present study were in agreement with Ezieshi and Olomu (2004) who observed decreased weight gain when up to 30, 43 or 75% of the maize fraction of the control diet was replaced by PKC (residual after expeller/press extraction of palm kernel oil). This finding was disagreement with Kamel et al. (1981), Gualtieri and Rapaccini (1990), Vandepopuliere et al. (1995) and Hussein et al. (1998a) who found that growth of chickens fed diets containing DP was similar to those fed control diet. Also, Osei and Amo (1987) reported that feeding different levels of PKC in isonitrogenous diets reduced feed efficiency but had no effect on body weights of broilers.

There were significant differences (p<0.05) in feed intake between diet 1 (control group) with 2 (10% DP) and 3 (20% DP). This result had adverse relation with the report of Olomu and Offiong (1980) and Olomu (1995) and was disagreement with those obtained by Ezieshi and Olomu (2004, 2008) and Iyayi and Davies (2005). In earlier, feed intake increased as metabolisable energy of diet decreased. The increase in feed intake invariably resulted in increased intake of crude protein and associated essential amino acids that were necessary for the optimum performance of birds.

By addition of DP the FCR significantly increased, which indicated poor utilisation of diets by the birds, probably due to higher crude fibre levels of the diets containing DP compared with the control diet. Kamel et al. (1981) and Hussein et al. (1998a) fed broiler chickens diets containing 5–15 and 8% DP, respectively. In contrast with this study, they concluded that addition of DP to broiler ration had no significant effect on efficiency of feed utilisation compare with control diet. Also, this result was disagreement with the findings of Ojewola and Ozuo (2006), Hussein and Alhadrami (2003) and Ezieshi and Olomu (2004).

The carcass characteristics of broiler chickens fed diets containing DP showed had same dressed weight, kitchen carcass weight, breast muscle, back, gizzard and liver percentage as control. Esuga et al. (2008) fed broiler chickens with diets containing Palm kernel meal and enzyme; they observed significant variation in the breast, neck, drumstick, wings, head, gizzard and intestinal length but no trend was established. The lungs, liver, kidneys, pancreas and intestines were within the normal range reported for chickens, suggesting the absence of toxic effects by the treatments. The results of carcass weight contradict with earlier reports. Garcia et al. (1999) reported that carcass weight was reduced when 6 and 10% PKC was used in broiler diets. The liver and lungs increased as the level of the PKC increased. Oloyo (1991) also reported higher liver weights when broilers were fed un-supplemented guinea corn/PKM-based ration. An increase in the percentage of heart in diet containing 30% DP probably was due to increase of its function. This agrees with Esuga et al. (2008) who reported that diet containing PKM without enzyme supplementation affects the relative size of some organs with relative reductions in the weights of such organs. A similar trend was observed with the liver as reported by Fasina et al. (2004) and Odunsi et al. (2006). Abonyi and Uchendu (2005) observed that finishing broilers fed 20% PKC had significantly higher final body weight and dressing weight percentage than control. Ojewola and Ozuo (2006) had earlier reported that growing cockerels fed 5% PKM as partial replacement for soybean meal had better performance indices than control birds, which is in disagreement with the results of present work.

Masoudi et al. (2010) reported that using DP reduces the cost of diets but had no significant effect on meat cost, as this could be due to the high fibre level of DP that were reported to reduce digestibility and possibly the availability of nutrients especially amino acids.

Addition of DP to diets resulted in a linear increase (p<0.05) of blood glucose concentration. This disagreed with the findings of Al-Bowait and Al-Sultan (2006) who reported that DP had no significant effect on glucose concentration of birds fed with diet containing DP; however, it agreed with the findings of Onifade (1997) who reported that glucose was accentuated high when fibrous diet was fed to broilers. It seems this effect of fibrous material contributed to increase in gluconeogenesis activity. The triglyceride concentration was not significantly different (p>0.05) between treatments. The control diet had lower triglyceride concentration (29.76 mg/dl) and diet 3 (58.28 mg/dl) had higher triglycerides concentration than other groups.

The HDL concentration was not significantly different (p>0.05) between diets. Treat 3 (20% DP) had higher HDL concentration than other treatments. LDL concentration had no significant difference (p>0.05) between diets. Control group had lower concentration (30.02 mg/dl) and group fed 10% DP had higher LDL concentration (84.72 mg/dl). Diets had no significant effect on VLDL concentration (p>0.05), the control group had lower and birds fed with 20% DP had higher VLDL concentration.

Since DP has a fibrous structure which supports low glucose than maize, maybe some effect of date pith on blood parameters contributes to its effect on increment of lipid metabolism for supporting the energy requirements of broiler. Increased total cholesterol and LDL levels may be related to an increased HMG CoA reductase activity (Qu et al. 2000).

5. Conclusion

The low protein and high fibre contents of DP are the major disadvantages that limit its use as feed ingredient for poultry, since birds require less fibre and more energy and protein in their diets. DP, however, could provide a cheap source of energy to birds if its digestibility is improved. Even though viscosity tends to decrease with aging (Peterson et al. 1993), it may well be that at higher levels of fibre occurrence in the diet; more enzymes are required to bring about the desirable viscosity that will enhance optimum nutrient absorption.