Effects of Delayed First Feeding Effects of Delayed First Feeding on the Development of the on the Development of the Digestive Tract and Skeletal Digestive Tract and Skeletal Muscles of Nile Tilapia, Muscles of Nile Tilapia, Oreochromis niloticus niloticus L. L. Oreochromis Melodina D. D. Fabillo Fabillo* , Annabelle A. Herrera, Ph.D.* * , Jose S. * , Annabelle A. Herrera, Ph.D.* * , Jose S. Melodina Abucay* * * , Ph.D * * * , Ph.D . Abucay . * University of the Philippines in the Visayas * University of the Philippines in the Visayas Tacloban Tacloban College College * * University of the Philippines, Diliman Diliman, , Quezon Quezon City City * * University of the Philippines, * * * Freshwater Aquaculture Center, College of Fisheries, Central * * * Freshwater Aquaculture Center, College of Fisheries, Central Luzon State University Luzon State University
I NTRODUCTI ON I NTRODUCTI ON During the last half century, fish farmers throughout the tropical and semi-tropical world have begun farming tilapia. Today, more than 90% of all commercially farmed tilapia are Nile tilapia, Oreochromis niloticus L. (Popma and Masser, 1999).
I NTRODUCTI ON I NTRODUCTI ON Second to milkfish, tilapia now ranks as the most important cultured fish in the Philippines (Guerrero, 1994). Tilapia farming is not only associated with its potential as a source of food, but also as an attractive source of investment (Bimbao and Smith, 1988).
I NTRODUCTI ON I n a NATURAL ENVI RONMENT where predators abound, female tilapias delay the release of their fry for protection. I n COMMERCI AL HATCHERI ES, delay in first feeding occurs when farmers fail to notice that the fry had already totally absorbed their yolk and are ready to receive exogenous food.
OBJECTI VES OF THE OBJECTI VES OF THE STUDY STUDY To trace the development To trace the development of the digestive tract and of the digestive tract and skeletal muscles of Nile skeletal muscles of Nile tilapia, O. O. niloticus niloticus L. from L. from tilapia, 0- -150 days post 150 days post- -feeding feeding 0 when first feeding is when first feeding is delayed delayed
SI GNI FI CANCE OF SI GNI FI CANCE OF THE STUDY THE STUDY essential to the understanding of whether the development of certain organs in nile tilapia larvae is most vulnerable during starvation allows tilapia farmers to decide the cost effectiveness of rearing previously starved fry up to their marketable size
MATERI ALS AND MATERI ALS AND METHODS METHODS Egg incubation and rearing of larvae – – 1 month 1 month Egg incubation and rearing of larvae Preliminary testing – – 10 days 10 days Preliminary testing Starvation and feeding experiments – – 5 months 5 months Starvation and feeding experiments Histology Histology Light Microscopy Electron Microscopy Light Microscopy Electron Microscopy (SEM and TEM) (SEM and TEM) Statistical analysis Statistical analysis
BREEDI NG AND REARI NG OF BREEDI NG AND REARI NG OF FRY OR LARVAE FRY OR LARVAE X X XX YY XX YY XY XY Genetically male tilapia (GMT) Genetically male tilapia (GMT)
PRE- - TRI AL EXPERI MENT TRI AL EXPERI MENT PRE 200 fry 200 fry 200 fry 1 st batch – one parental source 2nd batch – one parental source Starved until total mortality was observed Actual Experimentation
ACTUAL EXPERI MENTATI ON ACTUAL EXPERI MENTATI ON 1000 fry were used 1000 fry were used 200 200 200 200 200 T1 (control): T2: T3: T4: T5: fed starved starved starved starved immediately for 2 for 4 for 6 for 8 after yolk days days days days absorption sampling stocking in “hapas” sampling sampling 2 days 2 days 4, 6, 8, 20, 30, 60, 90, 150 days 4, 6, 8, 20, 30, 60, 90, 150 days
SAMPLI NG SAMPLI NG T2- T2 -starved starved T3- T3 -starved starved T4- T4 -starved starved T5- T5 -starved starved T1 (control) T1 (control) 2 days 2 days 4 days 4 days 6 days 6 days 8 days 8 days Day 0 Day 0 5 5 5 5 5 5 5 5 5 5 Day 2 5 5 5 5 5 Day 2 5 5 5 5 5 5 samples – – histology histology 5 samples Day 4 5 5 5 5 5 Day 4 5 5 5 5 5 Day 6 5 5 5 5 5 Day 6 5 5 5 5 5 3 samples– – SEM SEM 3 samples Day 8 5 5 5 5 5 Day 8 5 5 5 5 5 3 samples– – TEM TEM 3 samples Day 20 Day 20 5 5 5 5 5 5 5 5 5 5 3 samples - - histochemistry histochemistry 3 samples Day 30 Day 30 5 5 5 5 5 5 5 5 5 5 Day 60 5 5 5 5 5 Day 60 5 5 5 5 5 Day 90 5 5 5 5 5 Day 90 5 5 5 5 5 Day 120 Day 120 5 5 5 5 5 5 5 5 5 5 Day 150 14 14 14 14 14 Day 150 14 14 14 14 14
LI GHT MI CROSCOPY LI GHT MI CROSCOPY PURPOSE: to trace the development of the PURPOSE: to trace the development of the skeletal muscles and organs of the digestive skeletal muscles and organs of the digestive tract from day 0 (day of hatching) to day 150 tract from day 0 (day of hatching) to day 150 (adult marketable size). (adult marketable size). Dehydrated in alcohol series, mounted in glass slides Dehydrated in alcohol series, mounted in glass slides
EMPHASI S EMPHASI S TISSUE TISSUE Stomach – – height of mucosal fold Stomach height of mucosal fold (µ µm) m) layer ( Height of muscularis muscularis layer Height of Anterior and posterior Anterior and posterior intestine - - height of mucosal fold intestine height of mucosal fold (µ µm) m) layer ( Height of muscularis muscularis layer Height of Number of goblet cells Number of goblet cells Liver – – diameter of hepatic portal Liver diameter of hepatic portal (µ µm) m) vein ( vein Skeletal Muscles – – diameter diameter Skeletal Muscles of muscle fibers (µ µm) m) of muscle fibers ( Esophagus Esophagus Pancreas Pancreas
TRANSMI SSI ON ELECTRON TRANSMI SSI ON ELECTRON MI CROSCOPY MI CROSCOPY PURPOSE: to trace the development PURPOSE: to trace the development of the cells in the anterior intestine of the cells in the anterior intestine of the adult marketable fish (day of the adult marketable fish (day 150). 150). Processing Processing
SCANNI NG ELECTRON SCANNI NG ELECTRON PURPOSE: to examine the surface features of the anterior intestine of the adult marketable fish (day 150). Tissue processing Tissue processing
STATI STI CAL ANALYSI S STATI STI CAL ANALYSI S - Data were presented as means Data were presented as means ± ± - standard error. standard error. - Means were tested using Analysis of Means were tested using Analysis of - Variance (ANOVA) followed by Variance (ANOVA) followed by Duncan’s Multiple Range Test Duncan’s Multiple Range Test (DMRT). (DMRT). - Analyses were performed using Analyses were performed using - Statistical Analysis Software (SAS). Statistical Analysis Software (SAS).
RESULTS AND DI SCUSSI ON
RESULTS RESULTS Figure 1 . Comparison of the effect of delayed first feeding on the weight (grams) of 0-150 dph unstarved and starved O. niloticus . 20 weight (grams) unstarved 15 2 days starved 10 4 days starved 6 days starved 5 8 days starved 0 0 4 8 30 90 150 age (dph) of fish
Figure 2 . Comparison of the effect of delayed first feeding on the length (centimeters) of 0-150 dph unstarved and starved O. niloticus samples. length (centimeters) 10 unstarved 8 2 days starved 6 4 days starved 6 days starved 4 8 days starved 2 0 0 4 8 0 0 0 3 9 5 1 age (dph) of fish
Figure 3. Comparison of the effect of delayed first feeding on the gut length (centimeters) of 30-150 dph unstarved and starved O. niloticus samples . 80 gut length (cm) unstarved 60 2 days starved 40 4 days starved 20 6 days starved 0 8 days starved 30 60 90 120 150 age (dph) 0f fish
STARVATI ON STARVATI ON To deprive the nile tilapia fry of exogenous food, notwithstanding their readiness, is a form of STARVATION, which delayed their growth and development for lack of basic nutrients. This deprivation is a type of STRESS that organisms often encounter in nature (www.biol.unt.edu.,2004). Many pathological changes occur in a starved animal: decrease in size and weight; atrophy in the musculature; digestive tract becomes empty.
METHODS USED TO STUDY METHODS USED TO STUDY STARVATI ON I N FI SH STARVATI ON I N FI SH Morphological, histological or biochemical Morphological measurements have the advantages of ease and practicality of application as an indicator of starvation (Dou et al ., 2002). For this study, however, it was helpful to also use histological examination of tissues during starvation to validate the practicality and applicability of the morphological indicators used.
Fig. 4. Cross- -section of the anterior abdominal cavity of 6 section of the anterior abdominal cavity of 6 Fig. 4. Cross days post- -hatch ( hatch (dph dph) Nile Tilapia, 100X. ) Nile Tilapia, 100X. days post star ved star ved Unstar ved Unstar ved
Fig. 5. Cross- -section of the esophagus, stomach, and section of the esophagus, stomach, and Fig. 5. Cross intestine of an 8 dph dph starved Nile Tilapia, 100X. starved Nile Tilapia, 100X. intestine of an 8 star ved star ved
Fig. 6. Cross- -section of the anterior intestine of 6 section of the anterior intestine of 6 dph dph Fig. 6. Cross Nile Tilapia, X1000. Nile Tilapia, X1000. unstar ved star ved unstar ved star ved
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