The Use of Sapu-Sapu Fish (Hypostomus plecostomus) as Substitute of Commercial Feed to Improve Production Performance of Mojosari Ducks

MATERIALS AND METHODS

Experimental site: This study was performed in local farm in Mataram city of Lombok Island, Indonesia. Egg quality was evaluated in Animal Production Laboratory, Animal Husbandry Faculty, Mataram University. Cholesterol evaluation was performed in Hepatika Laboratory, Mataram, Indonesia.

Materials and research tools: One hundred 4-5 months old Mojosari laying ducks were obtained from local farmers in the Lombok Island. Twenty cages were made by bamboo partition. Each unit has a 1.5 m length and 1m width. Feeding and drinking apparatus were provided in each unit. Duck feed used in this study consisted of rice bran and sapu-sapu fish.

Sapu-sapu fish (SSF) was collected from rivers around Town of Mataram. Fresh fish was crushed using an 8 HP diesel engine prior to feeding.

Research procedure: The duck was weight using Ohause scale, to get uniform body weight and then distributed into 20 cages, 5 ducks for each cage. SSF was minced and mixed as treatment designed in Table 1.

Feed was given twice a day, in the morning and in the evening. The duck was adapted to treatment for one month period, before data collection. Eggs collection was performed in the morning, followed by feeding according to treatments. Evaluation of outer and inner part of egg quality and cholesterol content was performed after adaptation time of one month.

Data collection: Feed consumption is amount of feed consumed every day. Feed consumption was measured by amount of feed given to the duck minus feed left in the feed container every day. Daily eggs production was calculated by the number of eggs every day, divided by number of ducks from each treatment.

Weight gain was determined by taking duck weight at the end, minus at the beginning of study (g), beside the individual duck was weight every two weeks. Feed conversion ratio is an indicator of an efficient feed consumption. It was calculated as taking the amount of feed consumed and divided it by weight gain and eggs weight.

Eggs weight (g) was performed by using Ohaus scales. Eggs length (mm) was measured from the blunt part to the sharp part of egg, by using caliper scale. The distance of both sides of eggs was found to measure eggs width (mm) by using caliper. Eggs index was calculated by dividing the eggs width (mm) by eggs length (mm) and multiplied by 100. Eggs shell weight was found by breaking the eggs and let them dry, then weight it using “Ohaus” scale. Eggs shell thickness was measured by caliper.

Height of albumin was measured by putting it on a flat glass using depth micrometer. Albumin weight was measured using “Ohaus” scale by separating it from yolk using egg separator. Weight of egg yolk was measured using “Ohaus” scale after separated it from albumin. Color of eggs yolk was observed by breaking an egg, then separated it from albumin using separator and the yellow color was compared using Roche yolk color fan.

Haught Unit (HU) was calculated using the following equation as described by of Romanoff and Romanoff⁷:

Where
H : Height of albumin (mm)
W : Eggs weight (g)
G : Constants of gravitation (32.2)

At the end of the study, one egg was taken as a sample from each replication and send to Hepatika Laboratory, Mataram, Indonesia for the analysis of egg yolk cholesterol level using the method of AOAC 994.10:2012⁸.

Experimental design: The ducks were randomly assigned to four dietary treatments according to a completely randomized design (CRD). Each treatment consisted of five replicates with five ducks each. The dietary treatments were P0 consisted of 80% rice bran and 20% concentrate, P1 with 90% rice bran and 10% SSF, P2 with 80% rice bran and 20% SSF and P3 with 70% rice bran and 30% SSF.

Parameters measured: Feed intake and egg production were noted daily, while body weight was measured at the beginning and at the end of the observation period. The quality of the eggs was expressed in terms of egg weight (g), egg length (mm), egg depth (mm), egg shell weight (g) and thickness (mm), Haught Unit (HU), yolk color and meat cholesterol level was also measured.

Statistical analysis: Data were tabulated and analyzed using SPSS-17 software.

RESULTS AND DISCUSSION

Feed consumption: Production performances of Mojosari ducks fed on different levels of SSF is presented at Table 2. Feed consumption of the ducks fed diet containing SSF was not significantly (p>0.05) different from those given commercial feed. The feed consumption of ducks fed diet containing 20% commercial concentrate and those fed diet containing 10, 20 and 30% SSF were 171±7.26, 163±10.64, 171±10.3 and 163±16.0 g head‾¹ day‾¹ respectively.

Feed consumption noted in this study was slightly higher than those reported by Agustina et al.⁹ who found that the feed consumption of the ducks given probiotics was 144.92±2.12 g head‾¹ day‾¹ and study by Wardoyo¹⁰ who found that feed consumption of Khaki Campbell laying ducks at the age of 7 months given fermented rice bran was 133.40 -152.22 g head‾¹ but in accordance with those reported by Sarengat¹¹ who found that the feed consumption of Tegal ducks fed diet with a protein content (15.95%) and metabolizable energy (2800 kcal kg‾¹) were 151.44 g head‾¹ day‾¹. Many factors govern the amount of feed consumed by poultry. The most prominent factors are the metabolizable energy and protein contents.

Body weight gain: Average body weight gain of Mojosari layer ducks fed diet containing different amount of SSF, for three months (observation period) was significantly different (p<0.05). Average body weight gain of ducks received diet supplemented with 20 and 30% SSF was significantly higher (p<0.05) than those given commercial feed and those given diet supplemented with 10% SSF. Although their feed consumption was not significantly different, higher dietary protein content in both diets (Table 1) have permitted higher protein deposition as indicated by higher body weight gain (Fig. 1).

Egg production: There was no significant difference in egg production of the ducks fed diet supplemented with 20 or 30% SSF or those fed on control diet but those fed diet supplemented with 10% SSF was significantly lower than other dietary treatment. This discrepancy might be due to the protein content of the diets. Table 1 shows that protein content of diet supplemented with 20 and 30% SSF was slightly higher than control while diet containing 10% SSF was much lower than other diets. This indicate that the addition of 20% SSF in the diet of Mojosari laying ducks is sufficient to replace a commercial feed. Dietary protein is the most important factor that govern egg production. Shen¹² stated that the increase in dietary protein level from 15-17.5% can increase the egg production of duck. A previous study found that a group of ducks that consumed feed with high protein content (17.5 and 20%) gave significantly better egg production than the group that consumed feed with protein levels of 15 and 12.5%¹³, Fig. 2 shows the weekly egg production.

Feed conversion ratios (FCR): Feed conversion ratios of all ducks received diet supplemented with SSF were not significantly (p>0.05) different from those given commercial feed. The FCR of the ducks fed diet containing 20% commercial feed, 10, 20 and 30% SSF were 6.768±0.94, 7.985±1.94, 6.760±0.87 and 6.727±2.08 respectively. Similar FCR was reported by Iskandar et al.¹⁴ who fed the ducks with a diet containing 20% Rucah fish.

Exterior egg quality: Exterior egg quality parameters were determined by the amount of egg weight, egg shape index, shell thickness and egg shell weight. The results of exterior egg quality are presented in Table 3.

The diet containing SSF was significantly heavier than the weight of the egg produced by the ducks fed on commercial feed. Table 3 indicates that the higher the levels of SSF in the diet the heavier the egg is produced. Heavier egg weight in this study was caused by higher protein intake. Wahju¹⁵ suggested that protein in the feed is the main factor that affecting egg weight. Each treatment has different protein content, where the higher content of SSF resulted in higher protein content of the diet (Table 1). The egg weight noted in this study was higher than egg weight reported by Rasetyo and Usanti¹⁶ who found that the egg weight of Mojosari duck at first laying was 53.69 g. In another study Juliambarwati et al.¹⁷ reported that the egg weight of Mojosari ducks fed shrimp waste was between 55.89-58.36 g.

Egg shell weights of Mojosari ducks in the present study were 9.6 g (14.19%) to 14.2 g (20.1%) and did not affected by the inclusion levels of dietary SSF. These results are higher than those reported by Juliambarwati et al.¹⁷ who found that the egg shell weight of the ducks given shrimp waste varied from 5.82 g (10.12%) to 6.17 g (10.58%). Stadelman¹⁸ stated that the egg shell weight was 9 to 12% of the total egg weight. It is caused by a content of protein; energy, Ca and P were almost the same. According to Clunies et al.¹⁹, the higher dietary Ca can increase shell thickness. Similar trend was also observed in egg shell thickness. These might be due to almost similar amount of Ca and P in the diets.

Sarwono²⁰ reported that the birds fed with high calcium content usually produce a thick egg shell, while the eggshell thickness will affect the eggshell weight. In this study, eggshell weight and shell thickness did not significantly (p>0.05) affected by feeding SSF. Wahju¹⁵ reported that eggshell quality is determined by the thickness and structure of the eggshell. The content of Ca and P in the feed contributes to the quality of the eggshell because the eggshell formation is necessary for the carbonate ions and Ca ions sufficient to form CaCO₃ of eggshell. Clunies et al.¹⁹ observed that higher calcium intake increase the quality of the eggshell. The average of eggshell thickness in this study was 0.46-0.49 mm. This result is higher than those reported by Juliambarwati et al.¹⁷ who found that eggshell thickness of ducks fed shrimp waste ranged from 0.35-0.36 mm.

Egg shape index is the ratio of the width to the length of the egg. Romanoff and Romanoff⁷ found that the ideal egg shape index is 73.68%. Results of the present study showed that egg shape index of ducks fed diet containing 20% commercial concentrate, diet supplemented with 10%, 20% and 30% SSF, were 80.15±0.731%, 77.45±3.013%, 76.32±8.99% and 80.66±3.55% respectively.

The inner quality of eggs: Inner egg quality is determined by the albumin height, albumin weight, yolk weight and yolk color index. Inner egg quality in this study is presented in Table 4.

Egg albumen levels are indicated by the level of viscosity. The higher albumen indicates that the eggs are more viscous. The results showed that the ducks fed diet containing 30% SSF resulted in higher viscosity than those of the ducks fed diet containing 20% commercial feed, 10 and 20% SSF. Wahju¹⁵ noted that the higher egg albumin is an indicator for viscosity, which is influenced by feeding regimes and storage time.

Haugh Unit (HU) is an indicator to assess the freshness of eggs, which is influenced by storage time of the eggs. The results showed that HU values were not significantly affected (p>0.05) by dietary treatments. It may also be due to the egg retrieval time and uniform measurement in the morning shortly after the eggs came from ovipositor. North and Bell²¹ stated that the value of HU depends upon egg storage time and age of hens. HU value is not influenced by the composition of the feed if the protein and metabolizable energy of feed is well balanced.

Egg yolk color scores of the ducks fed diet containing SSF and commercial feed was significantly different (p<0.05). The average yolk color score of the duck fed commercial diet was 10.56±0.932, higher than the yolk color score of the duck fed diet containing 10% (3.4±1.140), 20% (5.8±0.447) and 30% (6.8±0.45) SSF. This might be due to commercial feed which contained corn and other ingredients that contains xanthophylls which provide more yellow yolk color. Yolk color difference in each treatment is presented in Fig. 3.

Egg and meat cholesterol: The cholesterol content in eggs and meat of ducks fed diet containing SSF are presented in Table 5. The results of the present study showed that the yolk cholesterol levels of the eggs produced by ducks fed diet containing 10, 20 and 30% SSF were lower than those of the ducks fed diet containing 20% commercial feed and significantly different (p<0.05). Similarly, cholesterol levels in meat tends to decrease significantly (p<0.05). Low yolk cholesterol levels of the egg laid by ducks fed diet containing SSF was due to the presence of omega-3 fatty acid. Griffin²² found that one of the functions of omega-3 is to inhibit the biosynthesis of cholesterol. Piliang and Al Haj²³ found that omega-3 fatty acids play a role in the regulation of cholesterol metabolism which includes transport and excretion of cholesterol. Patrick and Schaible²⁴ stated that saturated fatty acids are very rapidly absorbed by the digestive system, whereas omega-3 fatty acids (unsaturated) in fish oil will inhibit the biosynthesis of cholesterol and lowering triglycerides and VLDL cholesterol in blood plasma. According to Keshavaz²⁵ the fatty acids in egg yolk is influenced by the composition of fatty acids in the diet. If the diet contain high levels of unsaturated fatty acid such as omega-3 fatty acids, then those fatty acids are found in the eggs too.

Previous study²⁶ showed that Lemuru fish contains lots of omega-3 fatty acids that can lower cholesterol levels in egg yolk of quail. Suripta and Astuti²⁶ reported that the use of Lemuru fish oil in feed significantly lowered the cholesterol content (from 120.32-54.82 mg/100 g) in the quail eggs. Saerang²⁷ stated that the use of Lemuru fish oil in quail feed can lower cholesterol levels of the egg from 147.63-145.68 mg. Fish oils are rich in omega-3 fatty acids, if that oils are used in the feed of laying hens, It can decrease the cholesterol content of eggs and blood serum²⁸.

CONCLUSION

The diet of Mojosari ducks layer can be formulated using 20% sapu-sapu fish and 80% rice bran to replace similar amount of comercial feed. Inclusion of sapu-sapu fish in the diet resulted in better eggs quality compared to commercial feed. However, the egg yolk color was lighter. Yolk and meat cholesterol contents of the ducks fed diet containing sapu-sapu fish was found lower than those duck fed comercial feed.