Validation d'une technique de réduction de la production de méthane d'origine digestive chez la vache laitière en conditions commerciales

L’objectif principal de la présente recherche était d’évaluer les effets d’un supplément de lin extrudé dans la ration de troupeaux laitiers québécois sur les performances de production et les émissions de méthane (CH4) par les vaches laitières. Trente fermes ont été sélectionnées et divisées en deux groupes. Un premier groupe de 15 fermes a servi de témoin; les producteurs n’y ont pas apporté de changement à l’alimentation des vaches. Les 15 autres troupeaux formaient le groupe lin; les producteurs ont ajouté de 200 à 900 g/jour de supplément de lin extrudé (moyenne de 700 g/vache/jour) dans l’alimentation selon le stade de lactation. La période expérimentale s’est déroulée pendant les mois d’avril à octobre 2013. L’ajout de supplément de lin extrudé dans la ration a fait augmenter la production laitière de 3 % chez les troupeaux recevant le supplément comparativement aux troupeaux du groupe témoin (P < 0,05). L’ingestion de matière sèche a été similaire entre les deux groupes expérimentaux. Puisque la production laitière a été augmentée, l’efficacité alimentaire s’est améliorée de 6 % pour les troupeaux recevant le supplément de lin extrudé (P = 0,02). La teneur et la production de matières grasses du lait ont été similaires pour les deux groupes expérimentaux. La teneur en protéines du lait a diminué (P < 0,01), mais leur production n’a pas été affectée (P = 0,17), tandis que la production de lactose a augmenté (P = 0,02) lors de l’ajout du supplément de lin extrudé dans la ration sans en influencer la teneur (P = 0,60). La teneur en acides gras ω-3 a augmenté de 38 % dans les matières grasses du lait des troupeaux recevant le supplément (P < 0,01). Lorsqu’exprimées sur une base d’unité de lait produit, les émissions de CH4 estimées à partir de la composition en acides gras du lait, ont été réduites de 9,4 % pour les troupeaux recevant le supplément de lin extrudé comparativement au groupe témoin. En conclusion, une supplémentation modérée de lin extrudé (700 g/vache/jour) constitue un moyen pour réduire les émissions de CH4 tout en améliorant les performances de production des troupeaux laitiers et la qualité nutritionnelle du lait.

A LIN inspired optical bus for signal isolation in multilevel or modular power electronic converters

Proposed in this paper is a low-cost, half-duplex optical communication bus for control signal isolation in modular or multilevel power electronic converters. The concept is inspired by the Local Interconnect Network (LIN) serial network protocol as used in the automotive industry. The proposed communications bus utilises readily available optical transceivers and is suitable for use with low-cost microcontrollers for distributed control of multilevel converters. As a signal isolation concept, the proposed optical bus enables very high cell count modular multilevel cascaded converters (MMCCs) for high-bandwidth, high-voltage and high-power applications. Prototype hardware is developed and the optical bus concept is validated experimentally in a 33-level MMCC converter operating at 120 Vrms and 60 Hz.

Prueba de dos insecticidas sistémicos en dos formas de aplicación, en el control del tórsalo (Dermatobia hominis) Lin. Jr

Con el objeto de determinar cuál es el insecticida más efectivo en el control del tórsalo y la mejor forma de aplicación, se llevo a cabo un experimento en el Departamento de Boaco en el lapso comprendido de Julio a Diciembre de 1967. En cada finca se utilizaron cuarenta animales. Los insecticidas aplicados fueron: Ruelene 25 E en dosis de diez y siete miligramos por kilogramo de peso vivo y Neguvón en dosis de cincuenta miligramos por kilogramo de peso vivo. Los insecticidas se aplicaron en la forma siguiente: Ruelene 25 E vertido Ruelene 25 E solución Neguvón vertido Neguvón solución Se efectuaron recuentos de parásitos al principio del experimento y a los tres días y a los ocho días después de la aplicación de los insecticidas. El diseño experimental usado fue de bloques al azar con repeticiones y análisis dentro de las fincas. Los dos insecticidas y sus formas de aplicación estadísticamente tuvieron la misma efectividad, con porcentajes de control similares. el ruelene 25 E fue el insecticida de menor costo, en las dos formas de aplicación. Durante el experimento no se observaron efectos tóxicos en ningún animal. Se observó que el poder residual del Ruelene 25 E fue mayor que el del Neguvón.

The LIN-3 gene of the nematode C. elegans is the vulval-inducing signal

The development of the vulva of the nematode Caenorhabditis elegans is induced by a signal from the anchor cell of the somatic gonad. Activity of the gene lin-3 is required for the Vulval Precursor Cells (VPCs) to assume vulval fates. It is shown here that lin-3 encodes the vulval-inducing signal.

lin-3 was molecularly cloned by transposon-tagging and shown to encode a nematode member ofthe Epidermal Growth Factor (EGF) family. Genetic epistasis experiments indicate that lin-3 acts upstream of let-23, which encodes a homologue of the EGF-Receptor.

lin-3 transgenes that contain multiple copies of wild-type lin-3 genomic DNA clones confer a dominant multivulva phenotype in which up to all six of the VPCs assume vulval fates. The properties of these trans genes suggest that lin-3 can act in the anchor cell to induce vulval fates. Ablation of the gonadal precursors, which prevents the development of the AC, strongly reduces the ability of lin-3 transgenes to stimulate vulval development. A lin-3 recorder transgene that retains the ability to stimulate vulval development is expressed specifically in the anchor cell at the time of vulval induction.

Expression of an obligate secreted form of the EGF domain of Lin-S from a heterologous promoter is sufficient to induce vulval fates in the absence of the normal source of the inductive signal. This result suggests that Lin-S may act as a secreted factor, and that Lin-S may be the sole vulval-inducing signal made by the anchor cell.

lin-3 transgenes can cause adjacent VPCs to assume the 1° vulval fate and thus can override the action of the lateral signal mediated by lin-12 that normally prevents adjacent 1° fates. This indicates that the production of Lin-3 by the anchor cell must be limited to allow the VPCs to assume the proper pattern of fates of so 3° 3° 2° 1° 2° 3°.

Étude préliminaire sur l'incorporation de liants dans un aliment composé pour poisson d'élevage en Côte d'Ivoire

Artificial feeding constitutes a very important aspect for intensive fish culture. Then, the physical properties, particularly water stability of feed, wider influence the fish production. By trying to find some answers to these problems, a preliminary study on water stability has been conducted at the LAYO aquaculture research station. This work consisted in incorporating different types of binders available in tropical countries in fish pellets of 3.5 mm and 6.0 mm diameters in order to identify an efficient binder allowing the improvement of the water stability of feed. From this experiment, it comes out that the use of wheat flour (A1) gives excellent quality pellets followed by cassava flour residue (A3). Moreover, this study shows that it exists an influence of the diameter on the crumbling of the pellets.

Studies on growth and mortality of Cyprinus carpio (Lin.) in floating ponds

Growth and mortality rate of Cyprinus carpio (Linnaeus) under five different dietary conditions were studied in fifteen floating net cages in ponds of the Bangladesh Agricultural University Campus, Mymensingh. Growth rate was found to vary under different dietary conditions. The feed with mixture of 25% rice bran, 5% wheat bran, 30% linseed oil cake and 40% water hyacinth leaf meal exhibited the highest growth rate. The gain of log of body weight per unit increase of log of total length was significant. Significant survivals of the fishes were found.

Some aspects of association and development of Lytocestus indicus Moghe in catfish Clarias batrachus (Lin.)

Some aspects of association and development of the caryophyllid cestode Lytocestus indicus Moghe, 1925 infecting the catfish Clarias batrachus (Linn.) from the Kailla Beel of Mymensingh, Bangladesh were studied. About 33.14% of Clarias batrachus were infected with a mean intensity of 3.75, mean density 1.25. The infection was not found throughout the year. Two seasonal occurrence of this cestode were observed, one in April-May and the other in August-September. However, maturation period of the worm coincided with the maturation of the host. The worm was found attached to the wall of the intestine of the host. At the site of attachment tissue layers were compressed due to mechanical injuries. Prevalence and mean intensity of infection increased with length groups. No variation in infection was significantly observed in different sexes of the host examined.

Effects of some selective supplemental feeds on the survival and growth of catfish (Clarias batrachus Lin.) fry

Feeding experiments were conducted for 21 days to study the effect of live food (Tubifex sp.) and three prepared supplemental feeds on the growth and survival of 13 day old magur (C. batrachus) fry. It was observed that the growth of fry varied significantly (p<0.05) with different diets. The best growth was shown by the fry fed with Tubifex sp. followed by those fed with the diet containing yeast (30%), milk powder (30%) and chicken eggs (30%). The poorest growth rate was given by the fry fed on yeast (45%) and fish meal (45%). There was no significant difference in survival rates and condition factors among the fry fed with live food and prepared feeds.

Culture feasibility of african catfish (Clarias gariepinus Lin.) fry in glass tank and synthetic hapa system using supplemental diets

An experiment was carried out with 1 0 days old Clarias gariepinus fry over a period of 42 days to determine the effects of different feeds on growth and survival of African catfish fry in glass tanks. The experiment was designed into four treatments each having three replications. Thus treatment 1 (T1) was named as Tank Tubifex (TT) and treatment 2 (T2) as Tank Sabinco (TS), treatment 3 as Pond Tubifex (PT), and treatment 4 (T4) as Pond Sabinco (PS). Live Tubifex (protein levels 64.48%) was supplied to treatments 1 and 3 and rest of the treatments were supplied Sabinco starter-1 (protein levels 40.13%). The highest and the lowest growth in total length and weight were 12.90cm, 18.77g and 6.17cm, 4.04g recorded from the treatments 3 and 2, respectively. Growth of catfish fry under treatment 3 in terms of both length and weight were significantly higher (P<0.01) than those of the other treatments. However treatment 2 showed the significantly lowest (P<0.01) growth performance among the various treatments. The highest survival rate (92%) was also obtained with treatment 3. Tubifex proved to be the best larval feed in respect of growth and survival rate.

Evaluation on propagation of common carp (Cyprinus carpio Lin.) with hormonal and natural stimuli

The success of breeding of common carp (Cyprinus carpio) using hormonal inducement and environmental stimuli was evaluated considering different sex ratios, and natural and artificial substrates. A total of 18 females (weighing 250 to 2200g) divided into 6 treatments were investigated. A successful spawning was observed in all the treatment groups, only. 66.66% female responded successfully to LHRH-A combined with dompheridone and 83.33% female in natural stimuli. Females induced with LHRH-A and dompheridone found prompt ovulation than that of natural stimulation. A significant variation (F=7.45, P<0.05) was found among the different treatment groups. The number of eggs released appear to depend on body weight (t=15.72, P<0.05), sex ratio (t=7.96, P<0.05) and percentage of ovulated females (t=5.34, P<0.05). Although environmentally stimulated females released more eggs than injected female (t=5.18, P<0.05) but their survival rate was similar (t=1.77, P<0.05). Comparison between the two approaches under the conditions of AIT hatchery shown that both are suitable for spawning induction in common carp. However, environmental stimulation is advantageous because of the less labor and lower cost required for ovulation.

Rearing of Clarias batrachus (Lin.) larvae with formulated diets

An experiment was carried out for a period of 20 days using 7-day old Clarias batrachus larvae of initial total length of 7.4 ± 0.49 mm and weight of 2.9 ± 0.83 mg. Three artificial diets were used for the study having three replication of each. Among these, diet-I was formulated using 20% fish meal (FM), 30% powdered milk and 30% boiled egg yolk (BEY), diet-II using 27% FM, 20% Baker’s yeast (BY), 30% BEY and 3% agar and diet-III using 20% FM, 20% BY and 45% whole egg. The larvae fed on diets-II and III showed significantly (P<0.05) better length and weight gain than those of the larvae fed on diet-I. The larvae fed on diet- III showed the best survival rate (70%). However, the condition factor of the larvae fed on diet I was significantly better than those of the larvae fed on other two diets. The results of the study showed that C. batrachus larvae could be successfully reared with diet containing 45% whole egg, 20% yeast and 20% fish meal.

Rearing of catfish (Clarias batrachus Lin.) larvae with live and prepared feeds

Provision or live feed (Tubificid worms) attributed significantly better weight gain in the five days old Clarias batrachus larvae when reared for another 28 days compared to those fed mixed feed (live and artificial) and artificial feed only. Larvae fed mixed feed showed significantly better weight gain compared to those fed only artificial feed and the survival rate was similar to those fed only live feed. Both the weight gain and survival rate were the lowest for the larvae reared only on artificial feed.

Growth and survival of Clarias batrachus (Lin.) larvae fed on formulated diets

An experiment was conducted for a period of 28 days using 7-day old C. batrachus larvae of initial total length (±S.D.) of 7.4 ± 0.49 mm and weight (±S.D.) of 2.8 ± 0.75 mg. Five test diets viz. diets I, II, III, IV and V were prepared. Diet I was formulated using 30% fish meal (FM), 20% soybean meal (SM) and 20% Baker's yeast (BY), diet III using 15% FM, 20% SM, 15% cotton seed meal and 30% BY and diet IV using 20% FM, 30% BY and 30% powdered milk. The remaining two diets (diets II and V) were prepared using minced clam meat (96%) and BY (90%) respectively as the sole source of protein. Three replications were used for each treatment. The larvae fed on diet II exhibited significantly (P<0.05) better length gain and specific growth rate (SGR) than those of the larvae fed on diet III and there was no significant difference among the length gain and SGR of the larvae fed on diet I,II,IV and V. The larvae fed on diet II also showed significantly better weight gain and survival than those of the larvae fed on other diets. There was no significant difference between the condition factor of the larvae fed on diet II and IV. However, the larvae fed on diet II showed better condition factor than those of the larvae fed on other diets.

Growth and production performance of red tilapia and Nile tilapia (Oreochromis niloticus Lin.) under low-input culture system

Comparative production potential of red tilapia (a mutant hybrid of Oreochromis mossambicus) and Nile tilapia (Oreochromis niloticus) under low-input aquaculture was studied in six ponds of 360 m² each with an average water depth of 90 cm. Three ponds were stocked with fingerlings of O. niloticus (average weight 11.4±3.48 g) while three other ponds were stocked with red tilapia (average weight 10.72±2.5 g) at a density of 20,000 fingerlings/ha. Supplementary feed consisting of rice bran was given daily at 4-6% of standing biomass. Ponds were fertilized at fortnightly intervals with cattle manure 750 kg/ ha. After six months of rearing, gross fish productions of 3,218 and 3,017 kg/ha were obtained from O. niloticus and red tilapia ponds, respectively. Of this, table size fish (>80 g in size) production amounted to 2,366 and 2,823 kg/ha from O. niloticus and red tilapia culture, respectively. Analysis of cost and benefits showed higher benefit from red tilapia culture.