Judul: Supplementation of humic acid in the diet of tilapia Oreochromis niloticus cultured at water contaminated with lead (Pb)
Abstrak: Cemaran logam berat seperti Pb banyak ditemukan di beberapa perairan, baik danau maupun sungai, di Indonesia.Oleh karena itu, penelitian ini bertujuan mengevaluasi pengaruh penambahan asam humat dalam pakan terhadap kinerja pertumbuhan, histologi, dan kualitas daging ikan nila yang dipelihara pada air tercemar Pb. Terdapat empat perlakuan, yaitu penambahan asam humat ke dalam pakan sebanyak 0,0, 0,8, 1,6, dan 2,4 g/kg. Pakan-pakan tersebut diberikan ke ikan nila yang dipelihara di dalam air yang mengandung Pb 0,023-0,037 mg/L. Ikan nila berukuran 17,36±0,01 g sebanyak 15 ekor dipelihara pada akuarium berukuran 90x45x45 cm selama 55 hari. Ikan diberi pakan tiga kali sehari secara at satiation. Pergantian air dilakukan setiap hari sebanyak 95%. Perlakuan penambahan asam humat memiliki nilai laju pertumbuhan spesifik, jumlah kebutuhan pakan, rasio konversi pakan, rasio efisiensi protein, serta bobot akhir yang lebih baik dibanding tanpa penambahan asam humat. Humat 1,6 g/kg memiliki nilai biomassa yang berbeda nyata hingga 28,5% lebih tinggi dibandingkan Humat 0,0 g/kg. Terjadi kerusakan jaringan insang, hati, dan ginjal di seluruh perlakuan dengan tingkat kerusakan hati dan ginjal terparah pada perlakuan humat 0,0 g/kg. Humat 1,6 g/kg merupakan dosis optimal untuk ikan nila. Tidak ditemukan akumulasi Pb di daging ikan nila. Kata kunci: Asam humat, Oreochromis niloticus, Timbal (Pb), Heavy metal contamination such as Pb is found in several waters, both lakes and rivers, in Indonesia. Therefore, this study aimed to evaluate the effect of the addition of humic acid in the feed on the growth performance, histology, and meat quality of tilapia reared in Pb polluted water. There were four treatments, namely the addition of humic acid to the feed either of 0.0, 0.8, 1.6, and 2.4 g/kg. The feeds were given to tilapia reared in water containing Pb 0.023-0.037 mg/L. Fifteen tilapia measuring 17.36±0.01 g were kept in an aquarium measuring 90x45x45 cm for 55 days. Fish were fed three times a day at satiation. Water changes were carried out every day as much as 95%. The addition of humic acid had a better specific growth rate, total feed requirement, feed conversion ratio, protein efficiency ratio, and final weight than without the addition of humic acid. Humic 1.6 g/kg has a significantly different biomass value up to 28.5% higher than Humic 0.0 g/kg. There was damage to gill, liver, and kidney tissue in all treatments with the worst level of liver and kidney damage in the humic treatment of 0.0 g/kg. Humic 1.6 g/kg is the optimal dose for tilapia. No accumulation of Pb was found in tilapia meat. Keywords: Humic acid, Oreochromis niloticus, Lead (Pb)
Keyword: Humic acid, Oreochromis niloticus, Lead (Pb)

Judul: Addition of Humic Acid to Nile Tilapia Feed Oreochromis niloticus Raised in Aquatic Environments Polluted with Cadmium MetalAddition of Humic Acid to Nile Tilapia Feed Oreochromis niloticus Raised in Aquatic Environments Polluted with Cadmium Metal
Abstrak: Pencemaran Cd pada perairan dapat menyebabkan terjadinya akumulasi Cd pada daging ikan nila. Penelitian ini bertujuan mengevaluasi pengaruh penambahan asam humat pada pakan terhadap kinerja pertumbuhan, histologi dan kualitas daging ikan nila yang terpapar Cd. Perlakuan dosis asam humat, antara lain; kontrol, 0 , 800, 1.600, dan 2.400 mg kg-1 pakan. Ikan nila sebanyak 15 ekor dipelihara pada akuarium yang berukuran 0,5 x 0,5 x 0,4 m3 selama 60 hari dengan kandungan Cd 0,208 – 0,223 mg L-1. Akumulasi Cd pada daging perlakuan 2.400 sebesar 86,25 µg kg-1, serta laju pertumbuhan spesifik 2,39 % hari-1 dan tingkat kelangsungan hidup 78,33%. Akumulasi Cd pada daging perlakuan 0 sebesar 213 µg kg-1, laju pertumbuhan spesifik 2,21 % hari-1, dan tingkat kelangsungan hidup 58,33%. Berdasarkan BPOM 2018, kadar maksimum Cd pada daging sebesar 100 µg kg-1. Kerusakan sel insang dan hati pada ikan nila paling banyak ditemukan pada perlakuan 0. Penambahan asam humat pada pakan dapat meningkatkan kinerja pertumbuhan, menurunkan akumulasi Cd pada daging, serta mengurangi kerusakan sel pada insang dan hati ikan nila., Cd pollution in water can cause Cd accumulation in Tilapia fish meat. This study aims to evaluate the effect of adding humic acid to feed on growth performance, histology and meat quality of tilapia exposed to Cd. Treatment doses of humic acid include; control, 0, 800, 1,600, and 2,400 mg kg-1 feed. A total of 15 tilapia fish were kept in an aquarium measuring 0,5 x 0,5 x0,4 m3 for 60 days with a Cd content of 0.208 - 0.223 mg L-1. The accumulation of Cd in meat treated 2,400 was 86.25 µg kg-1, and the specific growth rate was 2.39% day-1 and the survival rate was 78.33%. Cd accumulation in treatment 0 meat was 213 µg kg-1, the specific growth rate was 2.21% day-1, and the survival rate was 58.33%. Based on BPOM 2018, the maximum Cd level in fish meat is 100 µg kg-1. The most damage to gill and liver cells was found at 0 dose. The addition of humic acid to feed can improve growth performance, reduce Cd accumulation in meat, and reduce cell damage to the gills and liver of tilapia.
Keyword: Asam Humat, kadmium, nila

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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