Effect of Replacing Fish Meal by Soybean Meal on the Performance, Nutrient Utilization and Egg Quality of Khaki Campbell Ducks in Late Laying Phase

India ranks second in world duck population, with a total duck population of around 33.5 millions according to the 20^th livestock census of India, 2019 (BAHS,2019 and Naik et al., 2022). Duck egg and meat are relished by people next to chicken and has higher market value. Fish meal is cherished by farmers and Nutritionists in developing countries because it is composed of higher content of digestible crude protein, essential amino acids, fats, vitamins and minerals (Blair, 2008 and Chadd, 2008). The nutritive value of fish meal is comparable to soybean meal in many aspects, but its protein quality and effectiveness of some unknown growth factors vary extensively (Swain and Chakurkar, 2011). Earlier studies revealed that protein from fish meal can be completely replaced by soybean meal protein with supplementation of 0.10% methionine in broiler ration economically (Aziz et al., 2001). Fish meal can be replaced by soybean meal as a main protein source along with supplementation of synthetic amino acids in the diet for ducklings and broilers (Yuan, 1989 and Okan and Ogun, 1988). Fish meal is an exceptional protein source for poultry feeding as it has ample quantity of all essential amino acids particularly lysine and methionine required by poultry (Scott et al., 1982). It is a excellent source of mysterious factors (Bondi, 1987). However, inadequate accessibility in recent years, want for consistency and elevated market price compared to vegetable protein sources has restricted its inclusion in broiler diets (Blair, 2008 and Chadd, 2008). Soybean meal has high protein and essential amino acid contents to meet the nutrient requirement of poultry (Yasothai, 2016). Therefore, the present study was conducted to evaluate the effect of replacing fish meal by soybean meal along with supplementation of additional lysine and methionine in the diet on the performance, nutrient utilization and egg quality of Khaki Campbell laying ducks in late laying phase.

The experiment was carried out at ICAR-Directorate of Poultry Research Regional Station, Bhubaneswar during April to July 2022. A control diet with fish meal and two experimental diets (Table 1) were formulated by replacing fish meal with soybean meal and supplementation of additional lysine and methionine i.e. T₁ (Fish meal 7%), T₂ (Fish meal-0%) and T₃ (Fish meal 0% + Lysine + Methionine). All the diets were made isonitrogenous and isocaloric. Seventy two Khaki Campbell laying ducks (83 weeks) were divided into three groups (each group had three replicates with 8 laying ducks per replicate) and were randomly fed above three diets for an experimental period of 16 weeks. All the birds were reared on deep litter system following standard management practices. The weekly feed intake, daily egg production and weekly egg weight were recorded and FCR was calculated as amount of feed consumed in kg to produce one dozen egg. The external egg quality parameters i.e. egg weight, length, width and shape index as per formula of Shultz (1953) were recorded. The internal egg quality parameters i.e. height of the albumen and yolk, length and width of the albumen and yolk were recorded and albumen index, yolk index and haugh unit were calculated as per the formula of Heiman and Carver (1936), Sharp and Powell (1930) and Haugh (1937), respectively. The feed cost to produce dozen egg was calculated. The proximate composition of fish meal, soybean meal and standard layer diet was analyzed (AOAC, 2005, Table 2). At the end of the biological trial, a metabolic trial was conducted with 4 days collection period by keeping the laying ducks in individual metabolic cages. A known quantity of feed was offered daily and excreta voided over 24 hr period was collected quantitatively. The aliquots of excreta were collected daily after mixing it well for dry matter and nitrogen estimation. For dry matter estimation the excreta samples were kept in hot air oven at 70°C for 72 hr (Sahoo et al., 2014). For faecal nitrogen estimation samples were preserved in 25% sulphuric acid in duplicate (Pathak and Kamra, 1999). The samples of feeds, residues and faeces were analyzed for proximate composition (AOAC, 2005). The metabolizability of the nutrients was calculated as the difference between nutrient intake and nutrient voided.
 

 

       
The data on various parameters were analysed (Snedecor and Cochran, 1989).  The  significant differences between the means were tested by Duncan’s multiple range test (Duncan, 1955).

The egg production, duck day egg production percent, egg weight and feed intake were significantly (P<0.05) higher in ducks fed diet with inclusion of fish meal (Table 3). The feed conversion ratio and cost of feed/dozen egg were significantly (P<0.05) better in laying ducks fed fish meal diet. Similar to present findings, Mundhem and Opstvedt (1981) observed that inclusion of fish meal in the diet of layers significantly increased the egg production with improvement in the efficiency of feed utilisation compared to soybean meal. In an earlier study, significantly higher (P<0.05) egg production and better feed conversion ratio were reported in laying hens fed 3% fish meal compared to control group fed only soybean meal (Rowghani et al., 2007).  In contrast, Yuan (1989) reported that fish meal can be replaced by soybean meal supplemented with synthetic amino acids for ducklings. There was significant decrease in egg production (Nos), duck day egg production % and poor FCR and cost of egg production per dozen eggs (Table 1) due to replacement of fish meal by soybean meal along with additional lysine and methionine. This may be due to the high quality protein in fish meal compared to plant protein source like soybean meal (Fanatico et al., (2018); highly available form of calcium and phosphorous in fish meal (Mile and Jacob, 2011); fish meal is an excellent source of all essential amino acids particularly lysine and methionine (Scott et al., 1982); it is also a good source of unidentified factors (Bondi, 1987). Earlier researchers also observed that the egg production, fertility and hatchability have improved due to inclusion of fish meal in the diet of laying hens (Almayehu et al., 2015). The above extraordinary nutritional qualities in fish meal might have increased the egg production significantly with a great margin in ducks fed fish meal compared to those fed soybean meal with or without additional lysine and methionine. In contrast, Thongwittaya and Tasaki (1996) observed normal egg production in laying ducks fed on a diet based on soybean meal (21%) with no fish meal, however, supplementation with methionine and lysine increased the egg production. Results of an earlier study demonstrated that replacement of fish meal with either different vegetable proteins or synthetic amino acids gave better results in efficiency of production and cost of production (Rama Rao et al., 1998). The digestibility/retention of dry matter (DM), organic matter (OM), crude protein (CP) and crude fibre (CF) were higher in ducks fed diet with fish meal compared to those fed diet without fish meal and with amino acid supplementation (Table 4). Higher DM metabolizability was reported in white pekin ducks (Naik et al., 2021) and in Khaki Campbell ducks (Joshi et al., 2015). However, lower DM digestibility was reported in White Pekin and Khaki Campbell ducks, respectively (Sahoo et al., 2014). The OM digestibility was higher than the values reported by Sahoo et al., (2014) and similar to Joshi et al., (2015). The metabolizability of CP values were higher than the values reported by Naik et al., (2021) and Sahoo et al., (2014). The metabolizability of EE in present study was significantly higher in T₂ group (without fish meal) and higher than the values reported by earlier workers (Joshi et al., 2015). The CF metabolizability values were higher than the values (41.57 to 51.23 and 59.57 to 62.05) reported by earlier workers (Sahoo et al., 2014 and Naik et al., 2021). The nitrogen balance (2.69 to 2.98) and nitrogen balance as % of N intake (75.93 to 78.75) were higher in groups fed fish meal compared to other treatment groups. Similar values of nitrogen balance (2.35 to 4.22) and lower nitrogen balance as % of N intake (67.40 to 70.09) were reported by earlier researchers (Naik et al., 2021). The difference in the values of nutrient metabolizability among the findings of various studies might be due to the difference in the feeding regimes. The egg weight was similar for all the treatment groups. However, higher (P<0.05) egg weight was reported in laying hens fed 3% fish meal compared to those fed only soybean meal as a protein source (Rowghani et al., 2007).  On the other hand, significant (P<0.05) increase in egg weight was reported in egg laying ducks and Hy-Line laying hens as dietary lysine level was increased (Fouad et al., 2018 and Proschaska et al., 1996). The egg quality parameters i.e. shape index, albumen index, yolk index, haugh units, shell thickness with and without membranes and albumen % were significantly (P<0.05) better in laying ducks fed diets with SBM (without fish meal diet) and diet 3 with addition of lysine and methionine (Table 5). Earlier researchers reported that albumen quality increased with increased dietary lysine concentration (Balnave et al., 2000). Since, better albumen quality implies better albumen height which is a indication of better albumen index and  haugh unit .This may be the reason of better egg quality i.e. albumen index and haugh unit in ducks fed diet with soybean meal replacing fish meal  with or without additional lysine and methionine.
 

 



       
However, earlier workers reported that dietary supplementation of lysine had no effects on egg shape index and haugh unit (Fouad et al., 2018). In contrast, no improvement in haugh unit in Hy-Line Brown laying hens and Hy-Line W-36 laying hens was reported due to dietary supplementation of lysine (da Rocha et al., 2009 and Souza et al., 2014). The value of haugh unit ranged from 92.51-97.24 in present study. In contrast, lower value (87.80 -90.45) was reported in Khaki Campbell laying ducks in earlier study (Swain et al., 2020). 

It may be concluded that replacement of fish meal by soybean meal reduced the performance of Khaki Campbell laying ducks in the late phase of laying in terms of lower egg production and egg weight and poor FCR. However, the egg quality was improved due to replacement of fish meal by soybean meal and with additional lysine and methionine.

The authors are thankful to Indian Council of Agricultural Research (ICAR), New Delhi, for providing financial support to conduct this study.

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