Performance, Serum Biochemical Profile, Slaughter Characteristics and Nutrient Retention of Vanaraja Chicks Fed Rice-based Distillers Dried Grains with Solubles in Diet

Scarcity and increasing price of soybean meal have been making it imperative to use alternate protein sources in poultry diets to sustain production and reduce the cost of egg and chicken meat production. Distillers’ dried grain with solubles (DDGS) is an important alternate protein supplement, which is available in appreciable quantities in recent years. The DDGS is produced as a by-product of the fermentation of cereal grains like maize, wheat, sorghum, rice, etc. for ethanol production. The starch portion of cereal is used up in the fermentation leaving the residual DDGS rich in protein, amino acids and other nutrients. However, large variation exists in the nutritional profile of DDGS (Swiatkiewicz et al., 2008; Salim et al., 2010) as the processing conditions employed and the raw material used varies widely from plant to plant. Maize-based DDGS could replace up to 33% of maize weight/weight in the diet of multi-colored broiler chicks, but showed negative effects at higher levels (66 and 100%) of replacement (Raju et al., 2011). The use of DDGS in broiler diets up to 15% decreased feed cost by replacing a part of corn and soybean meal, without any negative effect on growth performance and meat quality (Choi et al., 2008). Rew et al., (2009) studied the effects of corn DDGS (0, 10 and 20%) on production performance and economics in laying hens and observed no adverse effect on the performance of hens.
        
In contrast to the maize-DDGS, rice-based DDGS (r-DDGS) is less researched upon and the information available is limited. Rice-based DDGS is a good source of protein (48.4% CP) (Dey et al., 2019), amino acids (Luu et al., 2000; Xue et al., 2012) and other nutrients. In a previous study conducted at this lab, r-DDGS could be used up to 10% in broiler chicken diet and 7.5% in layer chicken, whereas at 15% in diet, r-DDGS significantly depressed the layer performance (Rama Rao et al., 2016). Similar negative effects were observed with r-DDGS at 15% in broiler diet by Dinani et al., (2018; 2019), while Gupta et al., (2018) reported no detrimental effects with 10% r-DDGS in layers. Besides, the beneficial effects of r-DDGS on immunity were observed at moderate levels in the broiler (Dinani et al., 2018) and layer (Gupta et al., 2017) diets. Vanaraja is a dual-purpose chicken variety developed at ICAR-DPR for rural poultry farming, which is being advocated to be reared under intensive system during the juvenile phase of 0-6 weeks of age and later under free-range backyard system. In the present study, the feeding value of r-DDGS was evaluated in the diet of Vanaraja chicks during the nursery phase of rearing.

The experiment was conducted at ICAR-Directorate of Poultry Research, Rajendranagar, Hyderabad, India from July to August 2017.
 
Rice-DDGS samples and experimental diets
 
Two lots of r-DDGS, viz. high protein (57% CP) and medium protein (47% CP) were procured from the market (M/s M.I. Feed Industries, Thane, Maharashtra and M/s Prorich Agro Foods, Panchkula, Haryana, respectively) and analysed for proximate composition (AOAC, 2016). The amino acid profile of r-DDGS was analysed employing wet chemistry (courtesy Evonik, Mumbai, India). A maize-soybean meal-based diet was compounded to serve as the control. Another 2 sets of diets were compounded containing high protein and medium protein r-DDGS, each at 5 and 10% level in the diet, thus making a total of 5 experimental diets (Table 1). All the diets were maintained isocaloric and isonitrogenous so as to eliminate the possible influence of nutrient variation on the performance and other variables of chickens.
 

 
Chicks and management
 
A total of 300 numbers of Vanaraja straight run chicks were procured from the Experimental Hatchery of ICAR-Directorate of Poultry Research, Hyderabad at day-old and divided into 5 treatment groups with 10 replicates of 6 chicks each and housed in 3-tiered raised wire floor SS battery brooder pens (2' × 2.5'/replicate) in an open-sided poultry house. The chicks were brooded by providing supplementary heat till 4 weeks of age using incandescent bulbs. The chicks were vaccinated against Newcastle and Infectious bursal diseases as per the standard schedule. Each of these experimental groups was fed one of the five experimental diets ad libitum from 0 to 6 weeks of age (Table 1). The nutrient concentration of various diets was maintained uniform during the experimental period to meet the requirements of Vanaraja chicks. The chicks were maintained under uniform managemental conditions throughout the trial.
 
Data collection
 
The effect of r-DDGS on body weight, feed intake and FCR (feed/body weight gain) was assessed at weekly intervals. The body weight was recorded prior to feeding the chicks. At 6 weeks of age, about two to three ml of blood was collected through the brachial vein from 10 chickens in each treatment group into non-heparinised tubes. Subsequently, serum was separated and analysed for the concentrations of total protein and cholesterol using reagent kits (Qualigens, Mumbai, India). At 6 weeks of age, one bird from each replicate (total 10 birds per treatment) were killed by decapitation and data on dressing yields and weights of visceral and lymphoid organs were recorded. Abdominal fat was collected as per Fancher and Jensen (1989). The weights were expressed relative to kg live weight. A piece of breast muscle from each carcass was collected, dried in a hot air oven at 80°C for 12 hours and analysed for crude protein content (AOAC, 2016). At the end of the experiment, a 3-day digestibility experiment was performed on a total of nine chicks, selected at random from each treatment and housed in three pens (2'×2.5') with three chicks each. The relative digestibility of dry matter was estimated by determining the proportion of the consumed amount that was retained. The experiment was conducted as per the guidelines of the Institute’s Animal Ethics Committee with their due approval.
 
Statistical analysis
 
The data were subjected to one-way analysis of variance under completely randomised design (Snedecor and Cochran, 1968) using SPSS software (version 15) and the means were compared by multiple range test (Duncan, 1955). The level of significance was considered at P≤0.05. Each replicate group was considered as the experimental unit for the data on body weight, feed intake, FCR and digestibility estimates, whereas for serum biochemical variables, the data of individual birds were considered for statistical analysis.

The body weight of Vanaraja chicks remained unaffected till 4 weeks of age, but at 5 weeks, the highest body weight was recorded with the 5% level of both the types of r-DDGS (Table 2). At 6 weeks, the body weight was significantly (P≤0.05) higher at the 5% level of both the types of r-DDGS in comparison to control and at a further higher level of 10% r-DDGS, the body weight, however, was similar to that of control. Thus, both the types of r-DDGS didn’t show any negative effect on body weight at the higher level indicating that r-DDGS in the diet was safe for Vanaraja chicks when added to diet up to 10% on the iso-nutrient basis. The results obtained in the current study with dual-purpose rural type chickens corroborate well with the trends reported on broiler chicken by Dinani et al., (2019), where r-DDGS was observed to be safe for broiler chicken up to 12.5% and at a further higher level of 15%, significant depression in growth was recorded. However, when r-DDGS was used at 12.5% level in combination with rice gluten meal (15%), adverse effects were reported on the intestinal histomorphometry and microbiology in broiler chicken (Dinani et al., 2018). The highest level (10%) tested in the current study was lower than the safe levels reported from the cited previous studies.
 
 

The positive effect of r-DDGS observed on body weight at the lower level of 5% could be attributed to the fermentation solubles and yeast residues present in DDGS, which were known to favourably influence the performance of chicks when fed in the diet (Radfar et al., 2013). Absence of such beneficial effect at the higher level of r-DDGS may be because these performance-enhancing attributes present in DDGS (like mannan in the yeast biomass) operate to their optimum at a particular concentration in the diet. This appears tenable, since in a dose-response study involving mannan oligosaccharide between 0 and 3g/kg diet in broilers (Tucker et al., 2003), the optimal dose was found to be around 1.5 g/kg. Feed intake was higher in all the groups fed r-DDGS, the difference being statistically significant (P≤0.05) at 3 weeks. Amino acids in DDGS are known to be less digestible to chickens causing their deficiency when DDGS is used in the diet (Stein et al., 2006). The increased feed intake observed with r-DDGS feeding could be considered as an attempt of the chicks to overcome nutrient deficiency due to poor digestibility values. Though the feed intake was higher in the groups fed r-DDGS, the feed conversion efficiency was poor at the higher levels of r-DDGS, which could be attributed to its low digestibility in comparison to soyabean meal.
        
The serum concentration of protein and cholesterol, DM digestibility and protein retention (Table 3), carcass yields and organ weights (Table 4) were not affected. Attia et al., (2017) also reported no effect of maize-DDGS on nutrient retention and plasma constituents in laying chickens even at 20% level in the diet. Furthermore, the length of the intestine was not affected, whereas the weight of the intestine was reduced in the groups fed r-DDGS, which was probably due to the adverse effects of r-DDGS on intestinal morphometry as reported by Dinani et al., (2018) in terms of reduced villus height, villus width and villus height to crypt depth ratio, when r-DDGS was fed in combination with rice gluten meal. Breast protein content increased significantly (P<0.05) with HP r-DDGS, while moderate increment was observed with MP r-DDGS (Table 3). The differences recorded between the two types of r-DDGS might be due to the possible variation in their amino acid digestibility.
 

 

The results of the study thus indicate that r-DDGS samples of both high and medium protein contents did not show any negative effects on performance, serum biochemical profile, nutrient retention and dressing yields of Vanaraja chicks, when included in the diet up to 10% on isocaloric and isonitrogenous basis, while beneficial effects on performance were noted at the lower level of 5% of r-DDGS in the diet.