Selasa, 17 September 2019

Minggu, 15 Oktober 2017

Selasa, 29 Desember 2015

Poultry Water Management and the Role of Water pH

Sumber naskah asli dari :
http://www.joneshamiltonag.com/poultry-water-management-and-the-role-of-water-ph/

Water management for poultry operations is a subject of much conversation between growers, veterinarians and live production personnel. The usage of water acidification as a preventive or treatment tool for disease management or to improve bird performance is probably one of the most poorly understood areas of poultry husbandry. This stems partly from the fact that until recently, no controlled research had been done investigating the preferred pH for poultry water consumption. Water acidification protocols for the prevention or management of certain bacterial diseases had been developed, but in many instances required a drinking water pH at bird level of 4.0 or below to be effective. Due to the lack of solid information on what type of water turkeys and chickens preferred, many within the industry were reluctant to acidify the drinking water to those biologically effective low levels. A high-pH crop environment (pH greater than 7.0) favors microflora that can hurt poultry performance. Poultry water treatment through acidification of the drinking water acidifies the crop, thereby encouraging the growth of favorable microflora while discouraging microflora that can harm intestinal integrity and function. Water acidification is most critical during the establishment of intestinal microflora and at each feed change when nutrient shifts can create instability in the normal intestinal microflora ecology. Using an animal feed grade mineral acid such as sodium bisulfate (PWT^® water acidifier, Jones-Hamilton Co.) to reduce the pH of drinking water to 4.0 during the critical periods of intestinal development helps the birds maintain the stability of intestinal microflora throughout the growing period. The establishment and maintenance of healthy intestinal microflora improves live production performance and cost.

How Crop Acidification Works

The reduction of Salmonella, Staph and Clostridium at the farm level focuses on creating a hostile environment to reduce horizontal spread from bird to bird and to reinforce the bird’s natural protection mechanisms. This is most critical when the birds are first placed into the house, when they are moved into the whole house or to the growout barn, and when they are withdrawn from feed.

Acidifying drinking water for poultry with sodium bisulfate for the first seven days of life provides a second layer of protection to the lactic acid producing bacteria (LAPBs) that are part of the crop’s normal ecology. This helps the newly hatched poult to maintain a low crop pH until it has established its own population of stable LAPBs. A low crop pH reduces the number of Salmonella or Clostridium that pass farther along the digestive tract and enables the bird to colonize with normal gut flora first. Once the crop’s LAPB population has been established, the bird will be able to maintain a low crop pH on its own as long as feed is available. When feed is withdrawn or turkeys are not eating for any reason, the normal population of LAPBs dies off and Salmonella will multiply in the crop. Acidifying the drinking water to a pH of 3.5 or below during times when feed is not available will prevent the crop pH from becoming too high.

Necessary Characteristics to Acidify Water without Affecting Consumption

A target pH of 3.5-4.0 is critical for bacterial control programs to work. Therefore, it is important to choose a mineral acid that birds will drink readily at that low pH. If the birds refuse to drink the water at the proper pH for crop acidification, the program will not work.

PWT^® water acidifier is the first FDA approved feed grade mineral acid water treatment available to the poultry industry. Due to the unique chemistry of PWT^®, the consumption of treated water is not decreased at higher concentrations as has been reported for organic acids. This advantage gives producers the flexibility for administration in a wide range of applications in all livestock and poultry species. All of the acids currently marketed to the poultry industry are weak organic acids, i.e. citric, acetic, lactic, that have poor taste profiles and limited pH reducing capabilities. Because PWT^® has a low pKa, it has a cleaner taste profile and profound acidification properties that should overcome all of the issues of using the weak organic acids.

An organic acid is an acid that has carbon in it such as lactic, acetic (vinegar) or proprionic acids. Organic acids are often characterized as being sour due to their pKa being above the solution pH (a lazy acid). Some suggest that organic acids will work anyway at a high pH but research on bacterial killing ability shows that final pH is the determining factor and not organic acid concentration. Field experience seems to support this as the final pH at bird level seems to be the determining factor of efficacy rather than organic acid concentration.

The ability to significantly reduce water pH without impacting water consumption is also of great advantage in cleaning water lines during the flock. The periodic cleaning of water lines with birds in the house is very desirable especially in areas with high levels of iron in the water. The use of organic acids to clean the water lines with birds in the house results in decreased water consumption during the cleaning period. With PWT^® water acidifier, the lines can be cleaned frequently without negatively impacting bird health or performance. In most houses a shift in pH is sufficient to clean the lines. In houses with iron water, the pH of the water at bird level should be a 4.0 or less during cleaning in order to reduce the negative impact of the iron content.

Finally, it is critical to use an animal feed grade or human food grade acid in the drinking water. Industrial grade liquid acids are not approved by FDA for animal consumption. PWT^® water acidifier contains Sodium Bisulfate Animal Feed Grade and is produced under the guidelines for “Manufacturing, Packaging and Distribution of Animal Feeds and Feed Ingredients.” It is produced in a manner that assures the quality required for consumption by food-producing animals and meets requirements that are necessary to minimize the potential for contamination. PWT^® is approved by the FDA for use in animal feed and water.

Sabtu, 19 September 2015

DAMPAK PEMBATASAN PRODUKSI DOC

Oleh : Muhammad Misbachul Munir

19 September 2015

Secara singkat, dapak posisif dari pembatasan DOC Broiler adalah :

1. Harga DOC akan terkendali dalam sesaat

2. Perusahaan pembibit akan mengalami kepastian harga DOC jualnya.
3. Perusahaan pembibit yang besar akan tetap besar

Sedangkan dampak negatif adalah :

1. Perusahaan pembibitan ayam sekala kecil akan gulung tikar

2. Rencana Aksi Nasional Pangan Dan Gizi 2011 – 2015 terganggu

3. Harga pakan ayam akan meningkat

4. Dalam jangka waktu tertentu akan ada stok bahan baku pakan terlalu lama

5. Point 4, akan memicu penyakit unggas yang tidak diketahui penyebabnya

6. Point 4, juga akan meningkatkan kompalin kualitas DOC

7. Produksi daging dalam negeri akan turun akibat pembatasan DOC dan point 5.

8. Pemotongan produksi terlampau besar pada perusahaan besar dalam
jangka pendek berdampak pada pendapatan perusahaan yang rendah.
9. Pemegang saham perusahaan pembibitan akan melepas sahamnya,
sehubungan poin 8.

Baca blog berikut ini :

PEMBATASAN PRODUKSI DOC BROILER

dan

MENJAGA DAN MENINGKATKAN SISTIM KEKEBALAN TUBUH AYAM BROILER MELALUI MANAJEMEN PAKAN

Siapa yang akan diuntungkan dalam pembatasan produksi DOC ini :

1. Perusahaan pembibitan sekala besar

2. Importir daging

3. Investor asing (karena nilai tukar rupiah rendah)

Mengutip pernyataan pembicara Mr Gordon Butland, konsultan perunggasan internasional pada ISeminar Perunggasan ke-8 ASOHI

"Hal penting yang dikemukakan adalah Brazil dan Thailand saat ini giat mengekspor produk unggasnya. Selain itu akan banyak perusahaan asing menjadikan India, Indonesia, China, dan negara di bagian Asia untuk target pasar ekspor."

PEMBATASAN PRODUKSI DOC BROILER

KEBIJAKAN PEMBATASAN BIBIT AYAM

Oleh : Muhammad Misbachul Munir, S.Pt., M.M.

(April 2015)

Sikap dengan sengaja menurunkan populasi DOC di saat harga rendah adalah tindakan yang kurang tepat, berikut analisanya

PEMAHAMAN PASAR INDUSTRI AYAM PEDAGING

Industri ayam pedaging masuk dalam pasar Oligopoli. Perusahaan dalam industri-industri seperti ini memiliki pesaing-pesaing, tetapi pada saat yang bersamaan tidak harus menghadapi kompetisi sehingga mereka menjadi price taker. Kaum ekonom menyebut sebagai kompetisi tidak sempurna.

Oligopoli memiliki struktur pasar dimana hanya terdapat sedikit penjual, masing-masing menjual barang yang sama atau identik dengan yang lain. Masing-masing perusahaan dapat membentuk persetujuan harga disebut Kolusi (Clollusion), dan perusahaan perusahaan yang bergerak dalam keseragaman disebut Kartel (Cartel). Jika suatu kartel terbentuk, maka pasar pada dasarnya dilayani oleh suatu monopoli. Tindakan semacam ini seringkali tidak mungkin dilakukan, karena adanya undang-undang antitrust.

Suatu kartel harus sepaham mengenai jumlah produksi total dan juga jumlah produksi masing-masing anggotanya. Tentu masing-masing anggota kartel mengiginkan keuntungan sama dengan anggota yang lain. Pertikaian diantara para anggota kartel mengenai pembagian keuntungan pasar seringkali membuat mereka tidak bisa bersatu. Semua anggota mengejar kepentingan masing-masing, hasil monopoli tidak bisa diraih dan keuntungan maksimal tidak akan bisa dicapai. Masing-masing berinteraksi dengan memilih strategi terbaik mereka dan dengan mempertimbangkan strategi yang dipilih oleh pihak lain hingga mencapai keseimbangan yang disebut Nash equilibrium.

Suatu contoh yang patut diperhatikan dalam memahami pasar Oligopoli adalah kartel dari produsen-produsen minyak dunia yang membentuk OPEC. Organisasi ini mencoba untuk meningkatkan harga minyak tetap tinggi dengan mengurangi produksi minyak yang diproduksi. OPEC mencoba mengatur tingkat produksi setiap negara anggotanya. OPEC sukses mengendalikan harga dari tahun 1973 sampai dengan 1985. Tetapi pada awal 1980-an negara-negara anggotanya mulai berselisih paham mengenai tingkat produksi, sehingga OPEC tidak efektif lagi. Sementara itu, kurangnya kerjasama antar negara penghasil minyak ini menyebabkan mereka mengalami kerugian (Mankiw, 2006).

Hal ini dapat dijelaskan dengan metrik berikut ini :

Ketika kartel mencoba untuk mempertahankan harga tetap pada posisi 4,0 satuan, dengan anggapan titik keseimbangan permintaan dan penawaran pada Q 93 satuan. Maka persusahaan A hanya akan memproduksi 17 satuan, sedangkan perusahaan D adalah 32 satuan. Tentu perusahaan A berkeinginan untuk memproduksi seperti perusahaan D. Oleh karena itu kebijakan pembatasan kuota produksi DOC yang sudah berlaku puluhan tahun ini tidak akan efektif.

SEBUAH KASUS PELANGGARAN UNDANG-UNDANG ANTITRUSH

Sumber : (Mankiw, 2006).

MENGAPA BERTAHUN TAHUN HARUS MENGURANGI PRODUKSI DOC BROILER

Marilah kita cermati data jumlah Perusahaan Peternakan Unggas dan Populasi ternak. Dari data terlihat bahwa jumlah Peternakan Perorangan semakin menurun dari tahun 2000 bahkan tidak ada sampai tahun 2013, akan tetapi jumlah peternakan PT/CV/Firma serta Yayasan semakin meningkat. Lalu jumlah ayam ras pedaging terus meningkat dari tahun ke tahun. Padahal dalam kenyataanya pemerintah beserta organisasi peternakan sering dan bahkan selalu melakukan pembatasan jumlah populasi unggas, terutama Broiler.

Mari kita baca lebih teliti, mengapa peternak perorangan justru menghilang mulai tahun 2008?, dan mengapa jumlah peternakan PT/CV/Firma dan Yayasan semakin berkembang.

Dari data tersebut di atas saja kita sudah tahu, bahwa “apakah benar kita sudah melakukan pembatasan jumlah ayam broiler?”. Jawabannya tentu pada data statistik tersebut di atas. Ternyata kita tidak sedang mengurangi populasi dan tidak bisa mengurangi populasi.

Apa yang semestinya dilakukan. Jawabnnya adalah meningkatkan permintaan DOC dengan menggeser kurva permintaan D1 ke D2, agar penawaran meningkat dari Q1 menjadi Q2, dengan demikian akan meningkatkan harga dari P1 ke P2.

Pertanyaan berikutnya, bagaimana menggeser kurve permintaan DOC dari D1 ke D2. Secara teoritis adalah dengan peningkatan pendapatan, harapan dan jumlah pembeli.

Dengan menghubungkan data statistik “Dirjen Peternakan”sebenarnya kita segera tahu bahwa ribuan peternak dari tahun 2000 sudah tidak terdaftar lagi sejak tahun 2008, tetapi tumbuh dan berkembang PT/CV/Firma serta Yayasan. Meskipun jumlah perusahaan ini sedikit, ternyata mampu menyerap sejumlah populasi yang selalu meningkat dari tahun ke tahun. Jadi untuk menaikkan harga, kartel ataupun pengambil keputusan harus meningkatkan jumlah permintaan. Dengan kata lain adalah meningkatkan jumlah peternak. Bukan melalui pengurangan populasi ternak seperti saat ini.

Jika kartel atau pengambil keputusan (pemerintah) lebih memilih pengurangan populasi DOC dari Q1 ke Q2, memang akan menggeser (menaikkan harga dari P1 ke P2), tapi mengakibatkan penawaran akan menurun dari S1 ke S2. Artinya akan mengurangi produksi perusahaan hulu. Karena sesuai dengan law of diminishing return perusahaan “Breeding” skala kecil akan tidak efisien, akibatnya akan gulung tikar, dan sebaliknya bagi perusahan “Breeding” skala besar yang lebih efisien akan tetap bertahan.

Disamping itu, apakah tindakan seperti ini tidak tergolong dalam upaya dari kartel perusahaan “Breeder” menjadi sebuah usaha yang monopoli?. Jika ini benar, maka hal ini bertentangan dengan undang-undang antitrust.

Selanjutnya, apabila jumlah populasi ternak ayam bergeser turun atas kebijakan penurunan populasi DOC dalam jangka panjang tentu akan menurunkan persediaan protein hewani asal daging ayam. Artinya Indonesia akan kalah dengan bangsa-bangsa lain sebagaimana tersebut pada tabel di bawah ini :

Sumber : http://www.slideshare.net/fransiscuswelirang.com/prospek-bisnis-unggas-ke-depan

Sumber : http://i1.wp.com/duniaindustri.com/wp-content/uploads/2015/09/ayam-malindo.jpg

Dan juga akan menggalkan “Rencana Aksi Nasional Pangan Dan Gizi 2011 – 2015” dari “Kementrian Perencaan Pembangunan Nasional”.

Dalam jangka pendek, upaya penurunan populasi DOC dari Q1 ke Q2 akan menguntungkan pihak-pihak tertentu. Sebagai gambaran adalah :

Jika kartel beserta pemerintah tetap menurunkan jumlah produksi DOC secara parsial dari Q1 ke Q2 dalam jangka waktu tertentu, maka akan memberikan dampak pada harga ayam pada jangka waktu tertentu pula. Bukankah DOC untuk menjadi daging layak konsumsi perlu waktu minimal 28 hari?. Untuk memperjelas, mari kita telaah kurve di bawah ini :

1). Anggap saja keseimbangan harga DOC semula terjadi pada Q1 (2,5 satuan) dengan harga P1 (23 satuan). Permintaan tinggi pada Q1 ini terkait dengan jumlah kandang yang belum terisi.

2). Karena jumlah kandang seluruh indonesia hanya itu itu saja, maka pada saat semua kandang sudah banyak yang terisi – permintaan DOC akan menurun dari Q1 (2,5 satuan) ke Q2 (1,5 satuan). Karena itu, harga terpengaruh turun dari P1 menjadi P2.

3). Ketika semua pelaku bisnis tahu bahwa harga DOC turun, maka kartel industri bisnis ayam broiler berupaya untuk menaikkan kembali harga DOC ke tingkat yang normal (anggap saja kembali pada P1). Jika jalan yang ditawarkan adalah mengurangi populasi DOC dari Q1 ke Q2, maka harga DOC tetap saja pada posisi P2, karena memang permintaan pada posisi Q2.

4). Jika pada evaluasi “penurunan populasi DOC” dari Q1 ke Q2 tidak mengubah harga DOC ke P2, lalu akan terus dilakukan upaya penurunan populasi lagi pada posisi Q3 misalnya, maka dampaknya dapat dilihat pada kurve di bawah ini :

5). Pada keadaan jumlah DOC Q2 saja, maka populasi ayam akan berkurang. Apabila permintaan akan daging ayam tetap (D1-ayam), maka seharusnya memerlukan jumlah populasi ayam Q1-ayam dengan harga P1-ayam.

6). Karena jumlah DOC menurun sampai level anggaplah Q2 saja, maka suatu saat jumlah populasi ayam – sama dengan populasi DOC (jika daya hidup 100%).

7). Karena populasi ayam pada posisi Q2-ayam akibat penawaran bergerak dari S1 turun ke S2, maka harga ayam akan meningkat dari P1-ayam ke P2-ayam.

8). Dengan demikian, untuk memenuhi permintaan pasar daging ayam masih memerlukan tambahan sebesar segitiga yang diarsir. Cara yang akan ditempuh pemerintah adalah import daging ayam.

9). Yang paling realistis adalah membeli ayam selagi harga rendah, lalu disimpan dalam keadaan beku di Cold Storage. Kemudian untuk memasok kekurangan suplay tersebut ketika harga P2-ayam.

10). Mengapa lebih menguntungkan membeli ayam ketika harga DOC rendah?. Karena ketika harga DOC rendah – harga ayam panen (1-1,2 Kg) juga rendah. Hal ini dapat dibuktikan dengan hasil analisa statistik dari data Mei 2009 - Agustus 2011 sebagai berikut :

Keterangan :

Sumberdata : Pinsar Unggas Nasional tahun 2009 – 2011

Jadi, amat sangat menguntungkan membeli ayam (panen) ketika harga DOC rendah.

11). Setelah panen, tentu kandang perlu diisi ayam kembali. Pada saat itulah kebutuhan akan meningkat dengan sendirinya dan menggeser kurva permintaan dari D2 ke D1. Dampaknya adalah meningkatkan harga dari P2 ke P1 kembali.

Jadi, sikap dengan sengaja menurunkan populasi DOC di saat harga rendah adalah tindakan yang kurang tepat. Jika harga rendah, tentu penawaran dengan sendirinya menurun dari S1 ke S2 (tanpa harus diturunkan ) sampai mencapai titik keseimbangan sendiri (Q3).

Permintaan DOC pada level Q3, mengakibatkan penawaran dari pihak perusahaan akan menurun secara alami. Dalam kondisi semacam ini perusahaan-perusahaan dengan skala kecil tidak akan mampu bertahan. Jika hal ini tetap saja dilakukan maka akan mempercepat proses gulung tikar pada industri “Breeder” skala kecil.

Jika jumlah Breeder berkurang, maka suplay DOC akan menurun dan suplay ayam broiler pun menurun. Akhirnya akan menurunkan konsumsi protein asal hewani. Jika bangsa kita memiliki asupan protein menurun maka kemungkinan besar kita memiki sumber daya dengan kemampuan yang rendah.

Rabu, 22 Juli 2015

SEMUT JEPANG (TENEBRIO MOLITOR)

APAKAH SEMUT JEPANG ITU ?

Istilah SEMUT JEPANG sudah banyak digunakan oleh masyarakat, tapi sebenarnya tidak mencirikan sebagai semut. Lebih cocok disebut kutu beras Tenebrio Molitor.

Perbedaan dari semut Jepang dibandingkan semut spesies lainnya yakni memiliki badan yang keras, bersayap namun tak bisa terbang, suka reproduksi, hidup secara berkelompok, bukan hewan kanibal.

Sumber : http://semutjepangdibogor.blogspot.com/2015_02_01_archive.html

BBPPTP Ambon, Ulat tepung (Tenebrio molitor) dikenal juga oleh kebanyakan masyarakat sebagai ulat hongkong. Imago dari serangga ini berupa kumbang yang termasuk dalam genusTenebrio yang memiliki warna merah kehitaman, hitam atau coklat gelap dan panjangnya 13-17 mm (Borror et al., 1982).

Sumber : http://ditjenbun.pertanian.go.id/bbpptpambon/berita-309-tenebrio-molitor-hama-pascapanen-yang-bermanfaat.html

Ciri dari semut jepang ini secara umum adalah memiliki tubuh berwarna hitam kecoklatan, berkaki enam dan tekstur tubuhnya cenderung keras. Hewan ini memiliki sayap yang mirip dengan kumbang. Namun semut jepang tidak dapat terbang seperti serangga bersayap lainya.

Sumber : http://mulaiusaharumahan.blogspot.com/2014/10/cara-budidaya-semut-jepang.html

Keunikan khas Semut jepang

Semut jepang memiliki ciri atau tanda seperti:

Suka atau cepat berkembangbiak
Hidup berkoloni atau berkelompok
Ruas badan lebih besar dari ruas kepala
Ukuran tubuh kecil hanya beberapa milimeter
Bukan tipe hewan pemakan daging/sesama
Memiliki sayap tapi tidak bisa terbang
Makanan ragi tape
Memiliki badan yang keras,
Memiliki kaki 6

Sumber : http://www.mearindo.com/2014/11/semut-jepang-solusi-untuk-asam-urat.html

Manfaat dan kegunaan dari semut Jepang menurut http://tipsdantrikampuh.blogspot.com/2014/09/manfaat-dan-kegunaan-dari-semut-jepang.html, adalah :

Semut Jepang berguna untuk menjadikan tingkat kolesterol di darah normal, khususnya untuk orang yang mempunyai kadar kolesterol tinggi pada darah.
Mengobati dan meringankan penyakit jantung.
Mengobati dan meringankan penyakit asam urat, khusus orang dengan kadar asam urat tinggi di tubuh.
Menjadikan jumlah gula di darah menjadi stabil, cocok untuk orang yang terserang penyakit diabetes.
Menjadikan tekanan darah stabil, khususnya untuk orang yang menderita hipertensi (penyakit darah tinggi).
Mampu menambah vitalitas dari pria maupun wanita, cocok bagi pria maupun wanita dengan jam kerja tinggi serta kesibukan untuk sehari-harinya, tubuh pun dapat menjadi lebih segar dengan semut Jepang.

Manfaat semut Jepang berdasarkan kajian ilmiah, kami paparkan sebagai berikut :

-------------------------------------------------------------

Sumber : http://en.cnki.com.cn/Article_en/CJFDTOTAL-HBNS200201007.htm

Hasilnya penelitian menunjukkan bahwa fungsi Tenebrio molitor pada tikus adalah dapat meningkatkan pertumbuhan, meningkatkan kemampuan belajar dan menghafal serta merupakan anti kelelahan dan kekurangan oksigen dan meningkatkan intelegent.

Sumber : http://en.cnki.com.cn/Article_en/CJFDTOTAL-HBNS200201007.htm

Hasilnya penelitian menunjukkan bahwa Tenebrio molitor merupakan protein alami berkualitas tinggi, namun penggunaannya baru sebatas hal yang terkait dengan kesehatan - karena keterbatasan teknologi.

Sumber : http://en.cnki.com.cn/Article_en/CJFDTOTAL-HBNS200703007.htm

Sumber : http://en.cnki.com.cn/Article_en/CJFDTOTAL-SPKJ200904103.htm

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Characteristics of Maize Flour Tortilla Supplemented with Ground Tenebrio molitor Larvae

Erick D. Aguilar-Miranda ,^† Mercedes G. López ,^‡ Clara Escamilla-Santana ,^§ and Ana P. Barba de la Rosa *^†

Instituto Tecnológico de Celaya, Avenida Tecnológico s/n, Celaya, Guanajuato 38010, México; Departamento de Biotecnología y Bioquímica, CINVESTAV-IPN, Km. 9.6 Libramiento Norte Carretera Irapuato-León, Irapuato, Guanajuato 36500, Mexico; and CES Internacional and Asociados, Cirilo Conejo 6, Querétaro, Querétaro, México

Abstract

The larva of the Tenebrio molitor, known as the yellow meal worm, is a plague of wheat and flours. Consumption of the raw insects is not well accepted because of their appearance. The objective of the present work was to grow T. molitor larvae under standard conditions, to analyze the chemical composition of the larvae powder, and to prepare supplemented maize tortillas. Protein and fat contents were performed with standard methods. Tenebrio larvae powder had a 58.4% protein content; this protein was rich in essential amino acids such as phenylalanine, tyrosine, and tryptophan; the found values satisfied those recommended by the Food and Agriculture Organization. Fatty acid composition was determined by GC-MS showing high contents of oleic acid and linoleic acid (19.8 and 8.51%, respectively). A large proportion of unsaturated fatty acids of longer chains was detected. Long-chain fatty acids having two or three double bonds have been claimed as highly beneficial to health. Tortillas supplemented with larvae powder had excellent consumer acceptance, and tortilla protein content increased by 2% as well as the amount of essential amino acids. These results show new ways to consume insects and at the same time increase the nutritional value of the original food products.

Sumber : http://pubs.acs.org/doi/pdf/10.1021/jf010691y
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Energy-efficient food production to reduce global warming and ecodegradation: The use of edible insects

Shri Manakula Vinayagar College of Engineering and Technology, Puducherry, India.

Abstract

As the global population continues to rise, and attempts to increase arable land area come in sharp conflict with the necessity to retain forests on one hand and pressures of urbanization on the other, the wave of global food shortage that has hit the world recently is likely to hit us again and again.

The increasing pressure on land is making meat production from macro-livestock less sustainable than ever before. To add to the diminishing pastures and broadening demand-supply gap of food grains are the shortages arising due to the diversion of some of the food crops for biofuel production. There is also an increasing use of fodder for generating biomass energy. The result is that even as the demand for animal protein keeps on rising with the swelling global population, there is every possibility that attempts to meet this demand would face serious crises in the coming years. The adverse impacts of global warming are conspiring to make the situation even worse than it otherwise would have been.

The present review brings home the fact that one of the possible ways to get around this problem is to extend the practice of entomophagy – use of insects as human food. As of now entomophagy is practiced in some regions and some cultures, but, by-and-large, the bulk of global population stay away from it. It is even looked down in several cultures and forbidden in some others. The review brings out the irrationality of omitting edible insects from human diet given the generally higher quality of nutrition they contain as compared to food based on macro-livestock. This aspect, coupled with much lesser consumption of energy and natural resources associated with insect-based protein production, makes entomophagy an option which deserves urgent global attention.

The authors highlight the relatively stronger sustainability of animal protein production by way of insect farming because, pound to pound, the production of insect protein takes much less land and energy than the more widely consumed forms of animal protein. It is estimated that over a thousand insect species are already a part of human diet and the nutrition offered by several of the species matches or surpasses that which is contained in traditional non-vegetarian foods. The paper also deals with the relevance of entomophagy as a potentially more ecologically compatible and sustainable source of animal protein than the red and the white meat on which most of the world presently depends. In the emerging global pattern based on an expanding share of renewable energy sources, entomophagy fits in as a renewable source of food energy for the future.

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Larvae of mealworm (Tenebrio molitor L.) as European novel food

Copyright © 2013 Ewa Siemianowska et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

For centuries, insects have been used as food due to their availability and easiness in raising that is much less burdensome for environment than animal husbandry breeding. Mealworm (Tenebrio molitor L.) is a store-pest of which larvae are consumed by people. The aim of the work was to determine the nutritional value of larvae of mealworm (Tenebrio molitor L.). The material was a three-month-old mealworm larva 25 - 30 mm in length. Larvae were boiled for 3 min and next dried in 60˚C. Contents of water, ash, minerals, protein, fat and fat acids profile have been determined. Fresh larvae contained 56% of water, 18% of total protein, 22% of total fat and 1.55% of ash. High contents of minerals were found in the larvae: magnesium (87.5 mg/100g), zinc (4.2 mg/100g), iron (3.8 mg/100g), copper (0.78 mg/100g) and manganese (0.44 mg/100g). The proportion of n-6/n-3 fatty acids was very advantageous and amounted to 6.76. Larvae powder contained twice higher content of protein, fat, ash and minerals. Larva of mealworm is a valuable source of nutrients in amounts more profitable for human organism than traditional meat food. Powdered larva is a high-grade product to be applied as a supplement to traditional meals.

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A digestive prolyl carboxypeptidase in Tenebrio molitor larvae

Irina A. Goptar a, Dmitry A. Shagin b, c, Irina A. Shagina c, Elena S. Mudrik c, Yulia A. Smirnova d, Dmitry P. Zhuzhikov e, Mikhail A. Belozersky d, Yakov E. Dunaevsky d, Brenda Oppert f, *, Irina Yu. Filippova a, Elena N. Elpidina d

a Chemical Faculty, Moscow State University, Moscow 119991, Russia

b Shemiakin and Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya 16/10, 117997 Moscow, Russia

c Evrogen JSC, Miklukho-Maklaya 16/10, 117997 Moscow, Russia

d A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia

e Biological Faculty, Moscow State University, Moscow 119991, Russia

f USDA Agricultural Research Service, Center for Grain and Animal Health Research, 1515 College Ave., Manhattan, KS 66502, USA

ABSTRACT

Prolyl carboxypeptidase (PRCP) is a lysosomal proline speciﬁc serine peptidase that also plays a vital role in the regulation of physiological processes in mammals. In this report, we isolate and characterize the ﬁrst PRCP in an insect. PRCP was puriﬁed from the anterior midgut of larvae of a stored product pest, Tenebrio molitor, using a three-step chromatography strategy, and it was determined that the puriﬁed enzyme was a dimer. The cDNA of PRCP was cloned and sequenced, and the predicted protein was identical to the proteomic sequences of the puriﬁed enzyme. The substrate speciﬁcity and kinetic parameters of the enzyme were determined. The T. molitor PRCP participates in the hydrolysis of the insect’s major dietary proteins, gliadins, and is the ﬁrst PRCP to be ascribed a digestive function. Our collective data suggest that the evolutionary enrichment of the digestive peptidase complex in insects with an area of acidic to neutral pH in the midgut is a result of the incorporation of lysosomal peptidases, including PRCP.

Introduction

Prolyl carboxypeptidase (PRCP; PCP, lysosomal carboxypeptidase, angiotensinase C, EC 3.4.16.2) belongs to a group of proline speciﬁc peptidases (PSP) (Cunningham and O’Connor, 1997) that are involved in the regulation of various metabolic processes (Vanhoof et al., 1995). PSP represent a relatively small group of highly speciﬁc exo- and endo-peptidases that cleave bonds formed by proline residues in proteins and peptides. The unique activity of PSP is due to the structural features of proline, the only cyclic imino acid among 20 α amino acids found in proteins and peptides. Peptide bonds containing proline residues are not hydrolyzed efﬁciently by most peptidases, and a proline residue in the peptide chain serves to protect against degradation by enzymes with broad speciﬁcity. The ability of PSP to hydrolyze this bond determines the speciﬁc activity of the enzyme in the regulation of metabolic processes.

PRCP are serine peptidases that catalyze the cleavage of a substrate at the C-terminal amino acid linked to a proline residue. At present, only PRCP from human (Odya et al., 1978; Tan et al., 1993; Shariat- Madar et al., 2002), pig (Yang et al., 1970; Kakimoto et al., 1973), monkey (Suzawa et al., 1995), and bacterium Xanthomonas malto- philia (Suga et al., 1995) have been isolated and studied. The primary structure of the isolated enzyme, present as a dimer in solution, has been described only for human PRCP, and the enzyme was assigned to the S28 family of serine peptidases (Tan et al., 1993). The crystal structure was solved recently and revealed that PRCP has a unique peptidase structure, with closest identity to dipeptidyl peptidase 7 (DPP7), containing a conserved a/b hydrolase domain and a novel helical SKS domain that caps the active site with the catalytic Ser-Asp- His triad (Abeywickrema et al., 2010; Soisson et al., 2010).

PRCP is widely distributed in human tissues, but mostly it is localized to the lungs, liver and placenta (Tan et al., 1993). The enzyme was initially found in human lysosomes (Yang et al., 1970; Kumamoto et al., 1981), but later it was found as a membrane- expressed enzyme in cultured human umbilical vein endothelial cells, explained by the association of PRCP with speciﬁc membrane proteins after exocytosis (Shariat-Madar et al., 2004).

The exact physiological functions for PRCP are not completely understood. The key role for mammalian PRCP is in regulating blood pressure (Kumamoto et al., 1981; Tamaoki et al., 1994; Kaplan and Ghebrehiwet, 2010; Hagedorn, 2011), but PRCP is also involved in processes of proliferation (Duan et al., 2011), inﬂammation (Kumamoto et al., 1981; Ngo et al., 2009) and angiogenesis (Mallela et al., 2009). PRCP also regulates food intake by inactivating a- melanocyte stimulating hormone (Wallingford et al., 2009; Shariat- Madar et al., 2010; Diano, 2011; Jeong et al., 2012). The only report of insect PRCP details changes in expression of the PRCP gene in response to magnesium exposure in Culex quinquefasciatus larvae (Zhao et al., 2010).

The present research on insect PSP is a part of our studies of digestive enzymes in larvae of the yellow mealworm, Tenebrio molitor (Coleoptera: Tenebrionidae), a pest of processed grains and stored products. The complex of digestive peptidases in T. molitor larvae differs substantially from human digestive enzymes, although both the beetle and people have grain products as a pri- mary food source. The major digestive organ of the larvae is the midgut, where a sharp pH gradient is found, from 5.6 in the anterior midgut (AM) to 7.9 in posterior midgut (PM) (Terra et al., 1985; Vinokurov et al., 2006a; Elpidina and Goptar, 2007). This gradient restricts the activity of different digestive enzymes in speciﬁc compartments of the midgut, which is usually consistent with the pH-optima of their activity (Vinokurov et al., 2006b).

The major digestive peptidases in the AM of T. molitor larvae are cysteine peptidases, represented by four to six distinct enzymes (Terra and Cristofoletti, 1996; Vinokurov et al., 2006a,b; Prabhakar et al., 2007). The major cysteine peptidase activity is cathepsin L (Cristofoletti et al., 2005; Beton et al., 2012; Oppert et al., 2012) known as a lysosomal peptidase in eukaryotes (Turk et al., 2012). In the PM of T. molitor larvae, digestive enzymes are mostly serine peptidases, including four trypsin-like and ﬁve chymotrypsin-like serine peptidases (Tsybina et al., 2005; Elpidina et al., 2005; Vinokurov et al., 2006a,b) as well as a membrane-bound amino- peptidase (Cristofoletti and Terra, 1999, 2000) and soluble carboxypeptidase (Ferreira et al., 1990; Prabhakar et al., 2007).

The major dietary proteins of T. molitor larvae, prolamins, contain 30-50% glutamine and 10-30% proline residues (Shewry and Tatham, 1990; Shewry and Halford, 2002). Therefore, we analyzed the major post-glutamine cleaving activities in the T. molitor larval digestive complex and found that they were cysteine peptidases (Goptar et al., 2012). Based on the composition of their diet, we also predicted the occurrence of digestive PSP in T. molitor larvae. Indeed, we described the ﬁrst proline-speciﬁc digestive peptidase in the midgut, which was a serine peptidase that speciﬁcally cleaved after proline, had an acidic pH optimum (5.3), and was found mainly in the AM contents (Goptar et al., 2008a,b), but the enzyme was not identiﬁed. In the present study, we identify this enzyme as a PRCP and detail the substrate speci- ﬁcity and kinetic parameters of the ﬁrst puriﬁed PRCP in an insect. Our data suggest that PRCP is a digestive enzyme in T. molitor larvae, which is a novel function for PRCP.

Discussion

In this paper, the ﬁrst PRCP was isolated from an insect, T. molitor larvae. For PRCP puriﬁcation, a three-stage scheme was used. The ﬁrst stage was by gel ﬁltration. The application of this type of chromatography effectively separated PRCP, with a molecular mass of 105 kDa, from the major digestive serine and cysteine endo- peptidases, with molecular masses less than 40 kDa (Vinokurov et al., 2006b) and therefore prevented proteolysis by endopepti- dases during puriﬁcation. Additional puriﬁcation followed with anion exchange and hydrophobic chromatography, resulting in a relatively pure enzyme. The cDNA of the T. molitor larval PRCP was cloned and sequenced, and the identity of the predicted PRCP sequence to the primary structure of the isolated enzyme was conﬁrmed by mass spectrometry. The ratio of the calculated molecular mass of cloned PRCP and that determined by gel ﬁltration suggests that the enzyme is a dimer, and similar data are reported for the human lysosomal PRCP (Odya et al., 1978; Tan et al., 1993). Also similar to the human PRCP, T. molitor PRCP displays acidic pH optimum at pH 5.6, correlating with its localization in the acidic AM of T. molitor larvae (Goptar et al., 2008b).

Previously, the primary structure of the enzyme was solved only for human PRCP, and the enzyme was assigned to the S28 family of serine peptidases (Tan et al., 1993). When PRCP was compared with annotated sequences of serine carboxypeptidases and POP, there was a low degree of overall identity (10e18%), but a high (67%) identity in active site amino acid residues. The authors concluded that PRCP is an evolutionary link connecting two families, POP and serine carboxypeptidases, because they possess properties char- acteristic of both families. Like serine carboxypeptidases, PRCP catalyzes the hydrolysis of a C-terminal residue that has a free carboxyl group at acidic pH values. On the other hand, PRCP hy- drolyzes bonds formed by the carbonyl group of proline residues as do POP, and a speciﬁc inhibitor of POP, Z-Pro-prolinal, inactivates PRCP as well.

Resolution of the 2.8 A crystal structure of the human lysosomal PRCP (Soisson et al., 2010) delineated the structural basis of the different substrate speciﬁcities of the two enzymes comprising the unique S28 family of PSP: carboxypeptidase PRCP and aminopep- tidase DPP7. PRCP has an extended active-site cleft that can accommodate proline substrates with multiple N-terminal resi- dues. In contrast, the substrate binding groove of DPP7 is occluded by a short amino acid insertion unique to DPP7 that creates a truncated active site selective for dipeptidyl proteolysis of N-ter- minal substrates.

The most speciﬁc substrate for T. molitor PRCP was N-protected peptide Z-PF, a selective substrate for PRCP, but the activity assay with this substrate was rather complicated. Because serine carboxypeptidases, unlike metallocarboxypeptidases, are able to hydrolyze chromogenic p-nitroanilide substrates with a detectable rate (Scheer et al., 2011), and due to the simplicity of the assay method, we used these substrates for monitoring of the puriﬁca- tion process and for the study of the substrate speciﬁcity. The best chromogenic peptide substrate was Z-AAP-pNA with the highest Vmax/Km value, despite the fact that the substrate had the lowest Km value. The hydrolysis of substrates Z-AP-pNA and AP-pNA occurred with equal efﬁciency, although Z-AP-pNA was more tightly bound to the enzyme, and AP-pNA was hydrolyzed faster. Lengthening or shortening the substrate by one Ala residue, substituting Ala at Gly, as well as removing the N-protecting group all led to an increase of the Km. The maximum rate of hydrolysis of Z-GP-pNA, a speciﬁc substrate for POP (Cunningham and O’Connor, 1997) and Z-P-pNA was an order of magnitude lower than for the other substrates.

Kinetic studies revealed complete competitive inhibition of T. molitor PRCP by Z-Pro-prolinal. In this type of inhibition, the in- hibitor interacts with the same region of the enzyme that binds substrate. Therefore the inhibitor competes with the substrate for interaction with the enzyme, as do other substrate-like inhibitors similar to Z-Pro-prolinal.

In contrast to human PRCP, which speciﬁcally functions as a regulatory enzyme affecting the blood system (Hagedorn, 2011; Adams et al., 2011), the PRCP from T. molitor is presumably a digestive enzyme. Earlier, we described the localization and func- tions of two PSPs from T. molitor larvae (Goptar et al., 2008a,b). We demonstrated that one of the PSPs had an acidic pH optimum, was localized in the AM contents, and the activity proﬁle changed in the digestive process similar to the general proteolytic activity, but these data were insufﬁcient for conclusive identiﬁcation of this peptidase. In this report, we identiﬁed this enzyme as PRCP and further demonstrate that T. molitor larval PRCP participates in gliadin hydrolysis that is reduced by a speciﬁc inhibitor of PRCP Z- Pro-prolinal.

Thus, we have isolated, puriﬁed, and identiﬁed the primary structure and further characterized a digestive PRCP from the larval midgut of an insect pest, T. molitor. The unique aspects of this enzyme are that it is the ﬁrst PRCP isolated from an insect, and the ﬁrst PRCP found to function as a secreted digestive enzyme. It is unknown if PRCP is involved in digestion in other animals. Speciﬁc digestive peptidases in insects that differentiate the mode of gliadin hydrolysis from that of human include cysteine peptidases with post-glutamine cleaving activity (Goptar et al., 2012), and PRCP with post-proline cleaving activity (this report). In eukaryotic organisms, these enzymes participate in the intracellular lysosomal degradation of proteins. Many insects rely on typical serine digestive peptidases, trypsin and chymotrypsin, but some groups of insects with an area of acidic to neutral pH in the midgut use cysteine cathepsins also for digestion (Terra and Ferreira, 1994). Our data suggest that the enrichment of the peptidase digestive complex in such insects during evolution is due to the adaptation of peptidases present in the lysosomes of eukaryotic organisms, such as cysteine cathepsins and PRCP.

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APAKAH "Prolyl carboxypeptidase" itu ?

Carboxypeptidase sikat enzim perbatasan pankreas yang membagi satu asam amino pada suatu waktu.
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Supplementation of l-carnitine in athletes:

does it make sense?

Heidrun Karlic, PhD, and Alfred Lohninger, PhD

From the Ludwig Boltzmann Institute for Leukemia Research and Hematology, Vienna, Austria; and the Department of Medical Chemistry, University of Vienna, Vienna, Austria

Abstract

Studies in athletes have shown that carnitine supplementation may foster exercise performance. As reported in the majority of studies, an increase in maximal oxygen consumption and a lowering of the respiratory quotient indicate that dietary carnitine has the potential to stimulate lipid metabolism. Treatment with l-carnitine also has been shown to induce a significant postexercise decrease in plasma lactate, which is formed and used continuously under fully aerobic conditions. Data from preliminary studies have indicated that l-carnitine supplementation can attenuate the deleterious effects of hypoxic training and speed up recovery from exercise stress. Recent data have indicated that l-carnitine plays a decisive role in the prevention of cellular damage and favorably affects recovery from exercise stress. Uptake of l-carnitine by blood cells may induce at least three mechanisms: 1) stimulation of hematopoiesis, 2) a dose-dependent inhibition of collagen-induced platelet aggregation, and 3) the prevention of programmed cell death in immune cells. As recently shown, carnitine has direct effects in regulation of gene expression (i.e., carnitine-acyltransferases) and may also exert effects via modulating intracellular fatty acid concentration. Thus there is evidence for a beneficial effect of l-carnitine supplementation in training, competition, and recovery from strenuous exercise and in regenerative athletics.

Correspondence to: Heidrun Karlic, PhD, Ludwig Boltzmann Institute for Leukemia Research and Hematology, Hanusch Hospital, H. Collinstr. 30, A-1140 Vienna, Austria.

INTRODUCTION

Dietary supplements to improve performance are familiar to many athletes. Manufacturers more or less aggressively claim that the substances improve the performance of athletes (i.e., act as ergo- genic aids) and/or speed up their recovery from exercise. Most of these claims are purely speculative and based on assumptions about how the dietary supplement influences metabolism. The substance L-carnitine has been particularly popular as a potential ergogenic aid because of its role in the conversion of fat into energy.1,2 For a scheme, the reader is referred to Figure 1.

L-carnitine was first discovered in muscle extracts by two Russian scientists3 who named the substance for the Latin word carnis (flesh or meat). Its chemical structure was established in 1927, and in 1935 a pioneer article about L-carnitine was published,4 which triggered numerous studies on the physiological functions of the chemical. In 1959 Fritz showed that carnitine increases long-chain fatty oxidation in liver and heart.5 Another name for L-carnitine was vitamin BT (T tenebrio) because the larva of black beetle Tenebrio molitor (Tenebrionidae, Coleoptera) requires L-carnitine as a growth factor in addition to folic acid and other known B vitamins. Considering the chemical structure, the choline-like metabolite L-carnitine (3-hydroxy-4-N,N,N- trimethylaminobutyrate, L-3-hydroxy-4-N-trimethylaminobutyric acid or-trimethylamino- -hydroxybutyric acid) is a quaternary amine. In phrenic nerve diaphragm preparations, its effect, namely induction of tetanic fade, can be reduced by addition of choline.6

FIG. 1. Role of L-carnitine in oxidative metabolism. L-carnitine’s primary function (blue arrows) is to “shuttle” fatty acids into the mitochondria by CPT-I. CPT-II mediates the further progression toward -oxidation. Car- nitine’s secondary function affects the CoASH/CoA ratio. CoASH is a two-carbon compound; CoA is a vitamin B derivative. Supplemental L-carnitine can react with some of the excess CoASH groups that accu- mulate during strenous exercise, thereby producing acetylcarnitine. This lowers the CoASH/CoA ratio, which in turn activates the enzyme PDH. PDH causes some pyruvate to be converted to CoASH as opposed to lactic acid. Less lactic acid can mean delayed fatigue. Further, L-carnitine reacts with the excess CoASH/CoA groups to form acetylcarnitine (green arrow), free CoA is released. Free CoA is necessary for continuous operation of the Krebs cycle. Moreover, stimulating PDH enhances flow through the Krebs cycle; as a consequence, maximum oxygen capacity (the capacity for aerobic regeneration of adenosine triphosphate) is increased. Together with a decreased respiratory quotient (the quotient of exhaled CO2 equivalents per inhaled O2), this can mean increased exercise performance. CoA, coenzyme; CoASH, CoASH, acetyl coenzyme A; CPT, carnitine palmi- toyltransferase; PDH, pyruvate dehydrogenase.

The function that has been investigated most thoroughly scientifically is the carnitine-dependent transport of fatty acids through the inner mitochondrial membrane. Other established functions of L-carnitine are the preservation of membrane integrity, the stabilization of a physiologic coenzyme A (CoA) acetyl-CoA (coASH) ratio in mitochondria, and the reduction of lactate pro- duction.7,8 In vitro investigations have strongly supported the notion that L-carnitine is able to inhibit apoptosis (programmed cell death)9 –11 (Figure 2).

The intracellular homeostasis of carnitine is controlled by different membrane transporters. The organic cation transporters (OCTNs), in particular OCTN2, physiologically the most important, operate on intestinal absorption and renal reabsorption of L-carnitine and play a major role in tissue distribution and varia- tions in transport rates. Inborn or acquired defects on this carnitine transport mechanism lead to primary or secondary carnitine deficiency. The OCTN2 mRNA content of cells is reduced with aging12 and by oxygen radicals.13 OCTN2 is directly inhibited by several agents and substances known to induce systemic carnitine deficiency.

Secondary carnitine deficiency is often seen in patients on regular hemodialysis,14 with metabolic disorders, and in pregnancy.15

L-carnitine, widely available over the counter, is also favored among athletes. Rumors that L-carnitine supplementation helped the Italian national soccer team to win the world championship in 1982 contributed immensely to its popularity. The most important claim relates to the role of carnitine in fat metabolism. L-carnitine is often advertized to improve fat metabolism, reduce fat mass, and increase muscle mass. In other words, the substance is portrayed as a “fat burner.” Therefore, carnitine is often recommended for conditions in which weight loss is indicated. Endurance athletes use carnitine to increase the oxidation of fat during exercise and spare muscle glycogen. This review critically examines whether the claims associated with L-carnitine are justified.

ROLE OF CARNITINE IN FAT METABOLISM

L-carnitine plays an important role in fat metabolism. In the overnight-fasted state, during the resting state, and during exercise of low to moderate intensity, longchain fatty acids represent up to 80% of the energy sources. The best described function of L-carnitine is in its role as a cofactor of carnitine, acyltransferases transporting long-chain fatty acids across the mitochondrial inner membrane.21 In the absence of L-carnitine, the inner mitochondrial membrane would be impermeable to long-chain fatty acids and fatty acyl-CoA esters. Once inside the mitochondria, these compounds can be degraded to acetyl-CoA through a process known as oxidation. Carnitine also plays a decisive role in maintaining the acetyl CoA/CoA ratio in the cell. During high-intensity exercise, there is a large production of acetyl-CoA. This increase in turn inhibits the pyruvate dehydrogenase (PDH) complex and reduces flux through the PDH complex.22 As a consequence, acetyl-CoA gives rise to lactate. Acetyl-CoA reacts with free carnitine to form acetyl-carnitine and CoA.

Carnitine therefore may supress the accumulation of lactic acid, thereby enhancing high-intensity exercise performance. This has been confirmed in several studies, which are summarized in Table I. Results from a pilot study in patients with the human immuno- deficiency virus receiving nucleoside analog therapy have sug- gested that L-carnitine may be helpful for patients who have nucleoside analog–related lactic acidosis with blood lactate levels higher than 10 mM/L.23 Sweeney et al.24 showed that addition of L-carnitine may improve the quality of platelet concentrates that are stored beyond 5 d by providing better pH preservation, less glucose consumption, and less lactate generation.

Historically, skeletal muscle was seen mainly as the site of lactate production during contraction, and lactate production was associated with insufficient muscle oxygenation and consequently fatigue. Later, it was recognized that skeletal muscles not only play an important role in lactate production but also in lactate clearance, and this improved understanding has led to a renewed interest in the metabolic fate of lactate in skeletal muscle and other tissues. Tracing studies using radioactive labeled lactate have shown that skeletal muscle extracts lactate from the circulation despite a substantial net lactate release, and that skeletal muscle has a large capacity for lactate oxidation; these processes are enhanced with exercise.