Effects of partial substitution of soybean meal with heat treated-dehulled Sweet lupin seed meal (Lupins angustifolius) on growth and carcass performances of broiler chickens

Alem Dida^1,2, Tegene Negesse² and Aberra Melesse²

¹ College of Agriculture and Natural Resource, Department of Animal Science, Selale University P O Box 245, Fitche, Ethiopia
alemdida32@gmail.com
² College of Agriculture, School of Animal and Range Sciences, Hawassa University, P O Box 05, Hawassa, Ethiopia

Abstract

The experiment was conducted with the objective to evaluate the effect of partial substitution of soybean meal (SBM) with heat treated dehulled lupin (Lupinus angustifolius) seed meal (SL) on performance of Cobb 500 breed of broilers. Two hundred unsexed day old chicks with similar weight were randomly assigned to four dietary treatments in completely randomized design with five replicates. Four dietary treatments were prepared with increasing level of SL replacing SBM at SL 0% (zero), SL 8% (SL8), SL 16% (SL16) and SL 24 % (SL24) based diets. Dietary treatments had similar crude protein (CP) content of 20.4, 20.5, 20.7 and 20.8 % for zero, SL8, SL16 and SL24 based diets, respectively. Total feed intake (g/bird) was 4110, 4156, 4225, and 4231 for zero, SL8, SL16, and SL24, respectively and was similar (p>0.05) among the dietary treatments. This could indicate that SL has comparable biological value with SBM on feed intake. Final body weight, daily body weight gain (DBWG) and total body weight gain were similar among zero, SL8, SL16 and SL24. The mean values of DBWG were 31.80, 30.67, 32.47, and 30.71 g/head/day for zero, SL8, SL16, and SL24, respectively. The carcass characteristics were similar among the dietary treatments. Dressing percentages were 70.7, 69.6, 68.8 and 69.0 % for zero, SL8, SL16 and SL24, respectively. Results indicated that substitution of SBM with SL up to 24% could be used safely as source of protein without any negative effect on growth performance and carcass components. Therefore, SL could be used as alternative protein source where SBM is scarce and unavailable for feeding Cobb 500 broiler chickens.

Key words: alternative feed sources, carcass, Cobb-500 broilers, feed conversion ratio, growth rate

Introduction

Around the world, the most commonly used dietary protein sources in poultry feed formulations are soybean meal, fish meal, and meat and bone meal. In recent years, however, future availability and the increasing cost and higher demand of soybean meal as a protein source in animal feed and ban of animal by-products, these ingredients are becoming serious threats to the continued expansion of the poultry industry (Nalle 2009). As a result, it has become necessary to search for alternative protein sources which can fully or partially substitute the conventional protein sources in poultry feed formulation. Among the conventional alternative protein sources that can be used for poultry feed formulation is sweet blue lupin seed (L. angustifolius) which is alkaloid free (L. angustifolius) which belongs to the family Fabaceae, are important sources of protein for monogastric animals and are considered as alternatives to the soybean meal (Al-sagan et al 2020). The use of lupin seed as feed of poultry primarily because of its high protein content (44 %DM) and high crude fat content (10.69% DM) (Mierlita 2015).

Lupin is a good source of nutrients, contains high proteins depending on the species 28-48% DM, rich in lysine and arginine; also good source lipids, minerals, and vitamins (Sobotka et al 2016). However the presence of anti-nutritional substances limit the importance of legume seed protein though the alkaloid content of sweet lupin seed is less than 0.01% (Yeheyis et al 2012). Moreover, lupin seed is characterized by low levels of starch, high levels of Non-Starch Polysaccharides (NSP). These properties affect the utilization of energy and contribute to the reduction of feed intake and digestibility, mainly in monogastrics. Improving the nutritional composition of lupin seed in addition to breeding efforts, other mechanisms like mechanical and biological processing methods such as grinding, soaking, heating, and dehulling etc., could be effective to reduce the anti-nutritional factors of lupin grain (Embaby 2010; Chilomer et al 2012; Omer et al 2016; Pieper et al 2016). Struti et al (2020) indicated that the dehulling process could reduce the deleterious effects of anti-nutritional factors such as tannins and fiber, with the remaining kernel having higher energy and protein contents. Mera-Zuniga et al (2019) reported that dehulling of lupin seed (L. angustifolius) increased protein from 25.0% to 31.1%, apparent metabolizable energy 1408.9 to 2101 kcal/kg. Raw sweet Blue lupin can be substituted in broilers' diets at 10% and results were similar in performance to the soybean meal diet, but the increasing level to 20% decreased performance and caused wet droppings (Al-sagan et al 2020). The suitability of various levels of L.angustifolius in broiler diets have been evaluated in several studies but no agreement have been reached with respect to the maximum level of lupin that could sustain broiler growth rates similar to those of a control diet. In the sight of these aspects, it is an important in extending our outlook on sweet lupin seed and help to promote its use as an important source of alternative protein feed in poultry diets. Therefore, the purpose the present experiment was to investigate effects of partial substitution of soybean meal with heat treated dehulled lupin seed meal at different levels on growth and carcass characteristics of Cobb-500 broiler chicken.

Materials and methods

Experimental site

The study was conducted at Batu (Ziway) town in a privately owned poultry farm. The area is located 160 km South East of the capital, Addis Abeba, Ethiopia. Geographically located at latitude of 7^o52’ East and longitude of 38°43’ North, with average altitude of 1640 masl. The average annual rainfall of the area is 760mm. The mean annual minimum and maximum temperature are 22 ^oC and 27 ^oC respectively.

Ingredients of the experimental diets

The dietary ingredients used in this experiment were maize (Zea mays), SBM (Glysine max), wheat bran, sweet lupin seed meal (L. angestifolius), wheat grain, limestone, fat (animal fat), lysine, and salt. All ingredients except the limestone and lupin seed meal were purchased from the local market. Limestone were purchased from chemical corporation industries (sodash). Sweet lupin seed (Lupinus angestifolius) were harvested from Adamitulu Agricultural Research Center in mid rift valley of Ethiopia under rain fed during the summer season (2018-2019). It is situated between 6°4′ N latitude and 37°34′ E longitude and at an altitude of 1,200 m above sea level. Seeds were harvested carefully and packed in bags of 100 kg capacity and transported to the experimental site.

Experimental feed

Processing of sweet lupin seeds- The raw sweet blue lupin seed were roasted on metal pan at a temperature of 130 ^oC for 15 minutes; it was then allowed to cool down. After cooling, the roasted seed was dehulled with the aid of a roller mill and the hulls were separated from the cotyledons by air (wind). The dehulled seed was then grounded using hammer mill as described by Laudadio et al (2010).

Experimental design

The experiment was conducted as a completely randomized design consisting of four dietary treatments each replicated five times. The experimental diets contained the controlled diet (zero) consisting of maize-soybean meals and three experimental diets (SL8, SL16 and SL24) in which the protein from SBM were partially replaced by SL at a rate of 8%, 16% and 24%, respectively.

Experimental birds and management

Before the start of the actual experiment, the experimental pens, watering and feeding troughs were thoroughly cleaned and disinfected. Each pen was having a dimension of 1.5 x 1.5m (2.25 m²); the floors of 20 pens were covered with sawdust and each pen was equipped with 250 watts infrared heat lamp brooder, feeding and watering troughs. Day old 200 Cobb-500 broiler chicks of similar body weight were used for the feeding trial. They were purchased from Alema Farms PLC Debre Zeit, Ethiopia. The chicks were first examined for outer anatomical defects and then individually weighed by a sensitive balance. The experimental chicks were randomly assigned to 20 pens, 10 chicks per pen (each treatment were replicated 5 times). The chickens were vaccinated against major poultry viral and bacterial diseases including Marek’s disease, Newcastle, infectious bursal disease (Gumboro), fowl typhoid and fowl pox diseases according to the schedule provided by the company where the chicks were purchased. The vaccines were obtained from National Veterinary Institute (Debre Zeit, Ethiopia). The chicks were provided with measured amount of feed on plastic tray for the first two weeks and on hanged round feeder for the next six weeks of age. Clean and fresh water was provided ad libitum with round type of waterer.

Data on feed intake body weight and feed conversion ratio (FCR)

Broiler chickens were fed on replicate basis and each day a measured amount of feed was offered at 08.00 AM and 16.00 PM. The amount of feed offered was adjusted on weekly basis. The leftover feed was always collected in the next morning before feed is offered and weighed. Feed intake was then determined by subtracting the leftover from the offered feed. Body weight was taken at the beginning of the experiment (considered as initial weight) and then on weekly basis in the morning at 7:00 AM before feeding. The body weight taken at the end of the experiment was considered as final body weight. Total body weight gain was then computed by subtracting the initial body weight from the final. Feed conversion ratio (FCR) values were calculated as a ratio of total feed intake (TFI) to total body weight gain (TBWG).

Carcass Analysis

At 56 days, two birds were randomly selected from each replicate, fasted overnight and slaughtered. The dressed carcass weight of birds were measured after removing head, shank and all visceral organs. The dressing percentage were calculated as the proportion of dressed carcass weight to slaughter weight multiplied by hundred.

Chemical analysis

Samples of feed ingredients, heat treated dehulled sweet blue lupin seed and feeds offered and refusal were analyzed for dry matter (DM), ash, ether extract (EE) and crude fiber (CF) by proximate analysis procedures (AOAC 1995). All samples except crude protein, calcium and phosphorus were analyzed in duplicates at Animal Nutrition Laboratory of School of Animal and Range Sciences, Hawassa University while the rest were analyzed in duplicates at Holeta agricultural research center. Total nitrogen content of the feed was determined using micro-Kjeldahl method and the (CP) was then calculated as nitrogen × 6.25. Calcium and phosphorus was determined by atomic absorption spectrophotometer (dry ashing) as described by AOAC (1995). The metabolizable energy (ME) of diets was estimated using the equation of Wiseman (1987: ME = 3,951+54.40 fat – 88.70 CF – 40.80 ash).

Statistical analysis

The experimental data collected on feed intake, body weight gain, feed conversion ratio and carcass analysis were subjected to one way analysis of variance in Complete Randomize Design (CRD) using SAS (SAS, 2002).

The following model was fitted to analyze the experimental data:

Yij = μ + ti + Ɛij,

Where; Yij = response variable, μ = overall mean, ti = treatment effect, and Ɛij = random error. The treatment means were separated using Tukey’s treatment comparison test at a significant level of α = 5%

Results and Discussion

Chemical composition of experimental diets

The chemical composition of dietary treatments and the feed ingredients used in the study are shown in Table 2. The crude protein contents of SL(L. angustifolius) used in the present study was 37.1% which was comparable with the value (37.22%) reported by Juoda et al (2017). However, it was lower than the value of 51.69% CP reported by Struti et al (2020) in sweet dehulled lupin seed. The CP content of sweet lupine ( L. angustifolius) could range from 27.5% to 44.9 % (Yeheyis et al 2012; Gebremedhn et al 2014; Smulikowska et al 2014). The different in CP content could be due to variety difference, rate and date of fertilizer application, agronomic condition and stage of harvesting, soil type and other factors (Yeheyis et al 2012). The CP content and metabolizable energy values of the dietary treatments were comparable and meet the protein and energy requirement of broilers (NRC 1994).

Ether extract (EE) content of SL was comparable to the value of 10.75-12.86 % of white lupin (Lupinus albus) and 11.3% of dehulled white lupin (L. albus) reported by Sturti et al (2020) and Mierlita (2018), respectively. The EE content of SL was also comparable to SBM (12.9 vs. 12.5%). Crude fiber (CF) content of SL was comparable to SBM (11.2 vs. 12.5%). Pieper et al (2016) stated that heat treatment and dehulling of sweet lupin seed meal increased the content of EE and reduce the CF which subsequently reduced the level of non-structural polysaccharides (NSP) that affect the utilization of energy (Vecerek et al 2008). In terms of Calcium (Ca) and Phosphorus (P) content of SL, the Ca and P content was lower than 0.207% DM and 0.45% DM, respectively reported by Laudadio et al (2010). In comparison to SBM the Ca and P content were lower in SL. Generally, SL is good source of CP, EE, and ME values.

Feed intake

As shown in Figure 1, the average weekly feed intake of broiler chickens fed different levels of SL based diets were comparable among dietary treatments. Similarly, Al-Sagan et al (2020) reported that blue lupine and/or probiotics did not significantly affect feed intake, body weight gain of broiler chickens. Furthermore, Tufarelli et al (2015) found that the inclusion of micronized dehulled lupin meal at 240 g/kg in the guinea fowl diet did not negatively affect the growth rate of birds during the whole feeding trial while the average daily feed intake was reduced in the lupin group. In contrary, Mera-Zuniga et al (2019) reported that broilers fed diets containing maize-dehulled lupine (L. angustifolius) seed with enzymes feed intake was increased in broilers fed maize-dehulled lupine than those fed maize –soybean meal diet. The increase in feed intake could be due to enzyme supplementation. In other study, Olkowski (2018) concluded that complete substitution of soybean meal with yellow lupin meal in the diet of broiler chickens led to significant decline of feed intake and growth rate. Results of the present study indicate that SL inclusion up to 24% in the diet did not affect the feed intake of broiler chickens.

Figure 1. Effect of different level of SL based diets on weekly feed intake of broilers

Growth performance of broilers

Table 3 indicate that there were no observed difference in final body weight (FBW), total body weight gain (TBWG), daily body weight gain (DBWG) and total feed intake among dietary treatments. The mean values of DBWG were 31.80, 30.67, 32.47, and 30.71 g/head/day for zero, SL8, SL16, and SL24, respectively. Similarly, Al-Sagan et al (2020) reported that comparable value of DBWG of broilers feed on 0%, 20% and 30% lupin seed meal based diets, wich were 55.5, 55.9, 55.5 g/day, respectively. Likewise, feed conversion ratio (FCR) did not vary across the treatment diets and indicated that inclusion of SL at 24% in the diet resulted in similar feed to gain ratio compared to SBM based diet. The present result is in agreement with Al-Sagan et al (2020), who reported that FCR of broilers fed on 0%, 20% and 30% lupin seed meal based diets were 1.45, 1.45 and 1.48, respectively. They reported that there was no significant difference in the FCR among broilers that were fed the 20% blue lupine diet and those that were fed the control or 30% blue lupine diets. However, Suchý et al (2010) reported increase in FCR as the level of lupin seed meal increased in the diets of broilers; which were 1.7, 1.82 and 1.87 kg feed / kg gain for the wheat-soybean (control), 15% lupin seed meal and 30% lupin seed meal based diet, respectively. Furthermore, Brand et al (2018) stated that poor FCR in broilers fed on lupin based diets were due to high and unable to utilize the NSP in the lupin seeds effectively, thus reduce total feed intake.

Figure 2 showed the trend in weekly body weight during the experimental period. The result shows that the inclusion of SL did not have much variation from those of the control treatment, which indicates that SL is a good replacer of SBM. Similarly, Tufarelli et al (2015) reported that inclusion of micronized dehulled lupin meal at 24 % in the guinea fowl diet did not negatively affect the growth rate of birds during the whole feeding trial. Krawczyk et al (2015) and Laudadio and Tufarelli (2011) also reported that the inclusion of yellow lupin seeds up to 24% in turkey diets and inclusion of treated lupin meal did not reduce the growth rate of chicks, respectively. However, Suchý et al (2010) stated that higher inclusion rate of lupin meal in diets might reduce the growth intensity of chickens. Mierlita and Diana (2013) reported that at the age of 21 days (end of starter phase) the average body weight was significantly higher in the case of control group of broilers.

Figure 2. Effect of different level of SL based diets on weekly body weight of broilers

Carcass characteristics of chickens

The effect of feeding different levels of heat treated dehulled sweet lupin seed meal on slaughter weight, dressed carcass weight and dressing percentage of different carcass components and organs of the experimental birds are presented in Table 4. Slaughter weights of chicken were different among the dietary treatments. Chickens fed with zero treatment diet had higher (p>0.05) slaughter weight compared to SL24 while those receiving SL8 and SL16 diets were comparable with that of the control diet. However, the results showed that there were no difference in main carcass components and dressing percentage among the dietary treatments. Similarly, Tufarelli et al (2015) reported no differences were observed on dressing percentage and major components of carcass (breast meat, drumstick, and thigh) in guinea fowl fed a diet with and without micronized-dehulled lupin meal. Furthermore, Laudadio and Tufarelli (2011) reported that replacing soybean meal with dehulled-micronised lupin meal at 24% in the diet of broiler chickens could produce meat with favourable lipid profile and quality, with no adverse effects on productive performance. This was fully in agreement with Nalle (2009). However, among the giblets, there were differences in liver weight among the dietary treatments; which were higher in the control (SBM) based diet compared to lupin containing diets. Similarly, Emiola et al (2007) reported that the presence of anti-nutritional factors in raw and dehulled kidney bean meals reduced the relative weights of the liver in birds. Other studies reported significant lower in slaughter weight and liver weight in broilers fed on heat treated dehulled lupin seed meal as compared to the control diet, which might be due to low bioavailability (biological value) of the nutrients in the diet with lupin seed meal compared to SBM (Mierlita and Diana (2013).

Conclusion

• Increasing level of substitution of SBM with SL up to 24% in broilers diet did not affect feed intake, body weight gain and feed conversion ratio.
  
  
• The result also indicated that dressing percentage and major carcass components were comparable among the diets.
  
  
• The overall result of this study showed that SL could substitute up to 24% of soybean meal in broiler rations without any adverse effect on growth performance and carcass characteristics of broiler chickens.

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