Average Daily Growth Research Articles

The effect of mineral complexes on the growth intensity of young bulls for sustainable agriculture

The article presents the material on the study of the influence of mineral granular complexes developed from mineral raw materials at the enterprise of JSC “United Chemical Company “URALCHEM” according to different recipes on the growth intensity, clinical-physiological and hematological parameters of Ayshir bulls. It was found that the young animals that received a mineral granular complex, developed according to four recipes, surpassed the analogues from the control in live weight by 7.17, 5.44, 6.01 and 8.56%, average daily growth by 17.61, 13.19, 14.74 and 19.82%. In the blood of young animals of the experimental groups, in comparison with analogues from the control, an increase in the content of erythrocytes by 0.53-5.74% and hemoglobin by 2.8, 0.4, 1.6 and 3.3 g/l were noted. The total protein in their blood serum contained more by 4.79, 1.67, 2.47 and 8.97% and albumins, respectively, by 10.15, 6.25, 3.82 and 17.02%. The use of mineral granular complexes in the feeding of bulls is economically expedient. Additional products for 32844-49368 rubles were obtained for groups of bulls who consumed mineral granular complex. The complexes developed according to recipes No. 1 and 4 showed the highest efficiency.

Influence of mineral and organic artificial substrates on productivity of covered ground tomato under additional lighting

The article presents the results of studying the reaction of tomato plants to an artificial substrate on which they are grown with all other things being equal — lighting, nutrition, temperature, and etc. Among the studied parameters, the plants reacted to the greatest extent with an average daily growth, filling of fruits, which mainly influenced the yield of tomatoes.

Determination of the Therapeutic Effect of the Use of Bacillus Coagulans in Calf Dyspepsia

The relevance of this study lies in the use of the probiotic strain of the microorganism B. coagulans ALM 86 for the treatment of diarrhoea in dairy calves and the reduction of the use of antibiotics in animal husbandry. The purpose of this paper was to establish the therapeutic effect in the treatment of diarrhoea in calves, the composition of the microflora, physiological indicators and metabolism using Bacillus coagulans ALM 86. The study used the following methods: microbiological, microscopic, biochemical, physiological, statistical. Studies have shown that the use of B. coagulans ALM 86 contributes to a decrease in the number of opportunistic microflora E. coli – by 90.8%, S. aureus – by 92.4%, S. enterica – by 88.01, an increase in Lactobacillus sp. by 130.8–151.58% and Bifidobacterium sp. by 272.7–469.8%. Administration of B. coagulans ALM 86 at a concentration of 1×109, CFU/g at a dose of 3–5 g helped stop diarrhoea and accelerate the development of scar digestion for four days in dairy calves, compared to the group where the antibiotic was used. An increase in average daily growth and feed consumption was found in the first experimental group by 19.7–15.0%, in the second – by 23.4–19.9% ​​(р≤0.05). A decrease in the level of total cholesterol with the use of B. coagulans ALM 86, an increase in the level of total protein by 18.57–22.6%, as a result of an increase in the content of total globulins by 49.3–57.37%, respectively (р≤0.05), were proven. Administration of B. coagulans ALM 86 at a concentration of 1×109, CFU/g at a dose of 3–5 g helped stop diarrhoea and accelerate the development of scar digestion for four days in dairy calves, compared to the group where the antibiotic was used. The obtained results of the study indicate the absence of toxic effects of the proposed dose of B. coagulans ALM 86 for the treatment of dyspepsia in calves and obtaining a positive effect. The practical value of the obtained results lies in the possibility of using B. coagulans ALM 86 in the treatment of diarrhoea in dairy calves without the use of antibiotics on animal farms of various designation.

Influence of Sunflower Meal, Dry Disstiler’s Grain and Alfalfa Silage as Protein Sources in the Feeding of Lambs after 25 kg

The aim of the present study is to compare the effect of including in rations sunflower meal, dry disstiler’s grain and alfalfa silage as protein sources when feeding breeding lambs after 25 kg live weight. 30 male and female lambs from the Pleven blackface sheep breed were used. The intake of concentrated feed from one animal is highest in lambs fed alfalfa silage (0,866 kg DM / day).The lowest cost for KER is observed for lambs fed on a dry disstiler’s growth based ration. The average daily growth on the 14th day is the highest, in the group fed with a ration based on dry disstiler’s grain - 294g. While on the 28th day, the average daily gain was highest in the group of lambs fed silage (296g), and on the 42nd day the same group maintained its highest growth (292g) compared to the other two groups. The lambs fed with three rations based on three protein sources (alfalfa silage, sunflower meal and dry disstiler’s grain) achieved an average daily growth of up to 0,291 g, and the differences in growth between the three groups of lambs were insignificant.

БИОЛОГИЧЕСКИ АКТИВНЫЕ ДОБАВКИ В КОРМЛЕНИИ ПОДСОСНЫХ СВИНОМАТОК И ПОРОСЯТ

The effect of feed additives Abiopeptide and Bio Iron on the productive qualities of suckling sows and piglets was studied. It has been established that their use leads to an increase in the milk production of sows, the average daily growth and safety of piglets.

DYNAMICS OF GROWTH OF LIVING WEIGHT OF UKRAINIAN RED-BROWN DAIRY BREED HEIFERS OF DIFFERENT LINES

The article presents the results of research on the dynamics of live weight growth, absolute, average daily and relative growth of heifers of the Ukrainian red-spotted dairy breed, obtained from breeders of different lines. The aim of the research was to establish the influence of linear affiliation on the growth dynamics of live weight of heifers. For this purpose, a database of 288 heifers was developed, which belongs to six lines: Chief, Elevation, Cavalier RF, Cadillac RF, Marshall and Starbuck. Live weight and gains were studied from birth to 15 months of age with an interval of 3 months according to generally accepted methods. Feeding and housing conditions for animals of all groups were the same. As a result of the conducted researches it is proved that live weight and gains of heifers depend on linear affiliation and age period. The average daily gain of heifers from birth to 3 months of age was in the range of 782.2-871.9 g, and was the highest compared to other age periods, except for heifers of the Cavalier RF. With age, the average daily gain decreased and reached its minimum in the last study period of 12-15 months - 598.6-687.9 g. For the entire study period from birth to 15 months of age, the average daily gain of heifers of all lines was 833.1-898, 0 g. In terms of linear affiliation, the best growth dynamics and increments were characterized by heifers originating from the breeders of the Marshall line. At 15 months of age, Marshall heifers weighed 387.4 kg, which is 7.8-26.3 kg more than their peers. Studies have shown that under the same conditions of feeding and keeping heifers obtained from the broods of the Marshall line grow faster and earlier reach the required live weight for the first insemination.

The effect of the genotype of servicing bulls on the growth and development of Hereford young stock

In the studies, the growth and development indicators of the Hereford young stock were studied, depending on the origin. The average daily growth of calf bulls aged 824±16.4 g, 8 months – 962.5±14.6 g, 9 months – 981.5±18.6 g, 12 months – 986.1±19.2 g. The height at hips of calf bulls aged 205 days was 109±11.7 cm, 8 months – 111±9.4 g, 9 months – 112±6.8 cm, 12 months – 124±7.9 cm. The average daily increase in heifers aged 205 days was 853.6±11.3 g, 8 months – 854.2±17.5 g, 9 months – 870.3±18.2 g, 12 months – 850±10.5 g, 15 months – 831.1±15.6 g, 18 months – 777.8±16.5 g. The height at hips of calves aged 205 days was 106±9.8 cm, 8 months – 109±7.8 g, 9 months – 110±11.1 cm, 12 months – 118±8.9 cm, 15 months – 121±10.9 cm, 18 months – 125±13.2 cm. It was found that the growth rate of calves and calf bulls on fattening is influenced by the father genotype. When comparing the average live weight of young stock at the age of 18 months, the best results were in calf bulls received from the bull Perets 3989 – 375.8±17.5 kg, this is 3.8 kg more than the same indicator for calf bulls received from the bull Timeline 2930348, and 7.8 kg more than the bull Emulation 2909514, and by the live weight of heifers at the age of 18 months the leader is the Timeline 2930348- 352.6±25.2 kg.

Effectiveness of Bacillus subtilis (Vitafort) probiotic used for raising broiler chickens

Unbalanced nutrition as well as diseases of infectious and non-infectious etiology lead to a decrease in production and a significant loss of farm animals and birds. To mitigate these problems, various probiotic drugs (probiotics) are introduced into the diets of birds and animals for preventive purposes. The aim of the research was to study the effect of the Vitafort probiotic, containing antagonistic bacteria of the endophytic strain Bacillus subtilis B11, on the body of broiler chickens. The effect of Vitafort was assessed by measuring the live weight and average daily growth of birds. In addition, a morphological study of blood was carried out and the content of Bacillus subtilis in the small intestine was determined. It was found that the endophytic strain Bacillus subtilis B11 improved the intestinal microflora. Thus, on day 5 of its use, the number of microorganisms varied from 4.1 × 104 to 8.2 × 104 CFU/g, and on day 42 the same number varied from 4 × 108 to 5.8 × 108 CFU/g on day 42, the contents of red blood cells, haemoglobin, and white blood cells in the blood of chickens from the experimental group were higher by 6.44%, 3.44%, and 2.11%, respectively, than they were in the control group. Considering the above facts, it can be assumed that the absorption of nutrients in the intestine improved, and metabolic processes were activated due to an increase in the transport abilities of red blood cells.

Retracted] Application of Nanoscaffold Material Combined with Exercise Rehabilitation Therapy in the Treatment of Athletes with Hip Injuries

A nanoscaffold is a porous scaffold. It injects antibiotics, cells, and polymer particles into damaged cavities in the form of injectables and forms hydrogels after the molecules self‐assemble at the injection site. Sports rehabilitation is a new frontier field integrating sports, health, and medicine, also known as physical therapy. It is the use of various sports methods for the injured or disabled, so that they can fully recover their physical functions and spirits, and can make them reintegrate into society. It mainly studies the relationship between sports and health. Among the tissue engineering scaffolds used as seed cell carriers, nanomaterials are playing an increasingly important role in the study of joint injury and repair due to their unique effects such as cell adhesion and proliferation. The purpose of this paper is to study a reliable nanoscaffold material for the treatment of patients with hip injuries in athletes and to observe its actual effect in combination with sports rehabilitation therapy. In this paper, an electrospinning method was proposed to prepare nanoscaffold materials, and the nanoscaffold materials were applied to the exercise rehabilitation process of two groups of hip patients, and the data of the patients’ rehabilitation were calculated. The results showed that the OD value of the cells in the exercise rehabilitation therapy using nanofiber scaffolds increased significantly, and the average daily growth rate of the OD value was 0.112. And the rehabilitation after 5 months was 19.8 points higher in hip range of motion score, 11.3 points higher in overall function score, and 6.2% lower in complication rate compared with ordinary exercise rehabilitation therapy. Therefore, it can be concluded that the therapy of the nanofiber scaffold material combined with exercise rehabilitation can more efficiently help patients with hip joint injury to recover, and the probability of complications is lower compared with the traditional exercise rehabilitation therapy.

СОПРЯЖЕННОСТЬ МЕЖДУ МЕТАБОЛИЗМОМ ЖИРНЫХ КИСЛОТ ЛИПИДОВ КРОВИ И ВЕСОВЫМ РОСТОМ ЯГНЯТ СТАВРОПОЛЬСКОЙ ПОРОДЫ, НОСИТЕЛЕЙ ГЕНОВ GHBB; GHAA; CASTNN; CASTMM

The article discusses the use of correlation analysis with the calculation of Pearson correlation coefficients. Calculations were carried out using biometric software. The presented material provides general information on the assessment of the degree of closeness of the relationship between the fatty acid spectrum of blood lipids, live weight and average daily growth of Stavropol breed lambs of different genotypes.

Effects of Bulk Tank Milk, Waste Milk, and Pasteurized Waste Milk on the Intake, Ruminal Parameters, Blood Parameters, Health, and Performance of Dairy Calves.

Simple SummaryWaste milk (WM) is commonly used in the feeding of calves. Due to its legal prohibition in commercialization, the destination of WM has become an environmental issue for dairy farms. Many dairy farms pasteurize WM, focusing on reducing the microbial load and related sanitary challenges. However, pasteurized milk may still contain toxins of bacterial origin, spores, and antibiotic residues. Few studies have evaluated the effects of whole milk, WM, and pasteurized WM (PWM) on the intake, ruminal parameters, blood parameters, health, and performance of dairy calves. In our study, feeding WM or PWM did not show significant negative effects on the intake, ruminal parameters, blood parameters, health, or performance of dairy calves. Understanding the effects of using WM and PWM on the health and performance of dairy calves requires further investigation.The aim of this study was to evaluate the effects of bulk tank milk (BTM), WM, and PWM on the intake, ruminal parameters, blood parameters, health, and performance of dairy calves. Forty-five male crossbred dairy calves (Gyr × Holstein) were used. On their fourth day of age, animals were grouped according to body weight, serum protein levels, and genetic composition. Three treatments were assessed: BTM (n = 15), WM from cows in antibiotic treatment (n = 15), and PWM via high-temperature, short-time pasteurization (72–74 °C for 16 s) (n = 15). During the experimental period (from 4 to 60 d of age), animals were fed 6 L of milk/d, divided into two equal meals. Water and concentrate were provided ad libitum. Daily measurements were made for milk, concentrate, and water intakes, as well as for fecal and respiratory scores. Rumen fluid and blood were sampled weekly. The following parameters were evaluated: volatile fatty acids (VFAs), pH and ammonia-N in rumen fluid, and β-hydroxybutyrate (BHB) and glucose in blood. Animals were weighed at birth, 4 d of age, and weekly up to 60 d of age. At the end of the experimental period (60 ± 1 d), all animals were euthanized for pulmonary evaluation. The randomized complete design with an interaction between treatment and week was the experimental method of choice for testing the hypothesis of the treatment’s effect on all evaluated outcomes. Animals in the BTM treatment had higher milk dry matter intake (DMI), followed by WM and PWM calves. Concentrate DMI was lower for BTM in comparison to WM and PWM calves. However, total DMI showed no significant differences between treatments. The rumen fluid from calves receiving PWM had higher concentrations of acetate and propionate than that of BTM and WM animals. No differences were observed between treatments for blood glucose and BHB concentrations. Health parameters (fecal and respiratory scores) and pneumonia occurrence showed no significant difference between treatments. No differences were observed for average daily gain (ADG) or body growth. Feeding WM and PWM did not show significant negative effects on the intake, ruminal parameters, blood parameters, health, or performance of dairy calves.

Комплексная кормовая добавка для бройлерного откорма утят

Abstract. The purpose of the research is to develop an effective feed additive with an optimal content of raw protein in combination with flavoring additives for ducklings, which allows to increase zoo technical and economic indicators with broiler technology of fattening young animals. Research methods. A scientific and production experiment was conducted on three groups of analog ducklings from a daily age to 49 days old. The studied indicators are: the dynamics of live weight by fattening phases, absolute and average daily growth, the safety of young animals, feed conversion, slaughter indicators, the European fattening efficiency indicator, the profitability of meat production. Results. The use of compound feeds with an optimal level of protein content in combination with flavoring additives prepared on the basis of developed feed additives intended for fattening broiler ducklings in the fattening phases contributes to an increase in: live weight by 11.4 %, the safety of young animals by 3 %, feed consumption and conversion by 3.9 and 7.6 %, slaughter yield of 1.1 %, the European fattening efficiency indicator from 246 to 308 units and the profitability of meat production by 24.5 %. Scientific novelty. For the first time, a complex feed additive has been developed, which, according to the age periods of fattening, includes three varieties: “Prestart”, intended for intensive fattening of young animals from daily to 10 days of age inclusive, “Start” for ducklings from 11 to 21 days and “Finish” from 22 to 49 days. The rate of introduction of the additive is 30 % of the mass of mixed feed. The composition of the supplement includes high-protein feeds, premixes, amino acids and flavoring substances (monosodium glutamate, acetic and citric acids, a mixture of phytogenics: oregano, cinnamon, red pepper).

Application effects of three ventilation methods on swine in winter

AbstractAn appropriate housing ventilation system is needed to ensure livestock and poultry health. In this study, 315 90‐d‐old Duroc × Landrace × Yorkshire (DLY) crossbred swine were distributed to three experimental swine houses. Each house had 105 swine, with 15 swine in each pen (including seven males and eight females). The ventilation systems for three houses were naturally ventilated, intermittent negative pressure longitudinal mechanical ventilation, and tunnel ventilation. The experiment was monitored for 28 consecutive days. The average temperature and relative humidity of the tunnel‐ventilated swine house were 19.22 °C and 60.79%, respectively, which were higher than other two swine houses (P < .05). The NH3 and CO2 concentrations in the tunnel‐ventilated swine house were lower than the other systems (P < .05). The average daily growth of swine in the tunnel ventilated was 14.9% higher (P < .05) than that in the natural ventilation. The feed/gain (F/G) ratio was 11.44% higher (P < .05) and abnormal behavior was lower in the tunnel ventilated swine house than those in the naturally ventilated swine house. Our results indicate that the tunnel ventilation is the best ventilation system for swine houses during the winter in northern China.

Analysis of Phytoplankton Structure Community, Water Quality and Cultivation Performance in Litopenaeus vannamei Intensive Pond Located in Tembokrejo Village, Muncar, Banyuwangi

Phytoplankton plays an important role in Litopenaeus vannamei cultivation. It plays a role as natural feed, water quality control, and indicator of shrimp cultivation success. The community structure of phytoplankton can be influenced by organic matter concentration in ponds. On the other hand, water quality and phytoplankton community structure also influence the productivity of shrimp cultivation. The research aimed to analyze the phytoplankton structure community, cultivation performance and the water quality in one of vananmei shrimp cultivation located in Muncar District. The research used the descriptive method. The research was conducted in two shrimp intensive system ponds in Tembokrejo Village, Muncar District, Banyuwangi, on February-March 2020. Parameters observed were composition, diversity, and density of phytoplankton, water quality parameters, and production performance in each pond. Based on the results, five phytoplankton classes was found: Bacillariophyceae (12 genera), Chlorophyceae (4 genera), Cyanophyceae (8 genera), Dinophyceae (2 genera), and Euglenophyceae (1 genus). Based on the density, Cyclotella and Chlorella were dominated in both ponds. Diversity index values on ponds 1 and ponds 2 were 1.64 and 1.71, respectively. The productivity of both ponds was 10.794 kg.ha-1 and 11.698 kg.ha-1, FCR (Feed Conversion Ratio) were 0.99 and 1.18, and ADG (Average Daily Growth) on both ponds were 0.16 g.day-1. Water quality parameters in both ponds showed an optimal range for vannamei cultivation, except phosphate, which is quite high. Overall, the cultivation performance of both ponds in our research showed good results. However, cultivation performance obtained in this research was not on its best performance yet due to Infectious Myonecrosis (IMNV) infection.Keywords: Cultivation performance, Litopenaeus vannamei, muncar, phytoplankton.

Результаты выращивания молоди ленского осетра (Acipenser baerii Brandt) в УЗВ на различных рецептурах кормов

The effect of Aller Arrow S and Aller Trident S formula feeds on the growth, development and accumulation of fat in the muscles of Lena sturgeon juveniles raised in the conditions of ultrasonic testing for a repair herd was studied. The obtained results of cultivation indicate the effectiveness of the use of Aller Arrow feeds to reduce fat accumulation. It is shown that production feeds with a fat content of 14% and a higher (by 4%) energy-protein ratio contribute to an increase in the fatness coefficient and a decrease in the progonicity index, their use leads to an increase in liver weight by 48.5% (p≥0.05), and the gastrointestinal tract by 5.6%. The ratio of connective and adipose tissues, the density of muscle fibers indicates a more intensive accumulation of fat when using Aller Trident S, which indirectly indicates a higher energy (gastronomic) value of meat, due to an increase in its caloric content. According to the average final mass, mass accumulation coefficient, yield and growth of ichthyomass, relative growth rate, average daily growth, the best results were obtained in juveniles raised on production feed, the economic effect was 400 rubles/m3 of the pool.

Pertumbuhan Trepang Holothuria scabra yang dipelihara dalam kurungan dengan substrat berbeda di Perairan Pantai Bahoi

This research was conducted to examine the effect of different substrates on the growth of Sea Cucumber Holothuria scabra reared in cages in Bahoi Coastal waters. This research was conducted from April to June 2021 in Bahoi Coastal Waters, West Likupang, North Minahasa. The method used in this research is the observation method with three treatments: A (sand), B (mud), C (seagrass), and three replications. The cages are made of nets size 100 cm x 100 cm x 50 cm as many as 9 cages. The sea cucumber size data was collected every two weeks. Samples of sea cucumber were taken randomly from each cage, left for ± 10 minutes, photographed, weighed, then recorded. Data collection for water quality is carried out every week during the day at the lowest tide, between 12:00 to 14:00. Water quality parameters were measured using a thermometer, refractometer, and litmus paper. Based on the research results, the average absolute weight growth and daily growth rate of sea cucumber reared with mud substrate showed the best results, that is 0.55 g and 0.72%, while the sand and seagrass substrates showed negative values. The results of ANOVA (analysis of variance) showed that there was no significant difference between absolute growth and daily growth rate of Sea Cucumber H. scabra reared on sand, mud, and seagrass substrates.

MINI WHEEL APPLICATION ON HOUSEHOLD SCALE AQUACULTURE OF GIANT FRESHWATER PRAWNS (Macrobranchium rosenbergii)

Giant freshwater prawns, one of the freshwater aquaculture commodities which has high economic value and has wide market opportunity. Dissolved oxygen on giant freshwater prawn aquaculture is the one of necessary part on a prawn weight gain. Availability of dissolved oxygen can be increased by optimalization on mini wheel and blower use. Mini Wheel is a part of aquaculture technology application, especially on household scale aquaculture of giant freshwater prawn (M. rosenbergii). This assembly used recycle material which can still be used. This mini wheel was modified by 3 treatments, that A (blower without mini wheel pond treatment); B (one-propeller mini wheel pond treatment); C (two-propeller mini wheel pond treatment). This research used quantitative method and every treatment should has three repetitions. Aquaculture a household scale by applying mini wheel designed to find out its effect on water quality and growth of giant freshwater prawn (M. rosenbergii), with parameter ABW (Average Body Weight), ADG (Average Daily Growth), FCR (Feed Convertion Ratio) and SR (Survival Rate). This research showed that there is a significant difference between two-propeller mini wheel pond treatment, one-propeller mini wheel pond treatment and blower without mini wheel pond treatment. The optimum Dissolved Oxygen value on two-propeller mini wheel pond treatment was about 9 mg/L (morning and afternoon testing), Pond temperature on range 280C, and also pH has stability on 7. The best growth was found in two-propeller mini wheel pond treatment with Survival Rate (SR) 93%, Average Body Weight (ABW) 10 g/prawn, Average Daily Growth (ADG) 0.11 g/prawn, and Feed Convertion Ratio (FCR) 1.5.

Culture of snubnose pompano, Trachinotus blochii (Lacepede, 1801) in indigenous re-circulatory aquaculture system using low cost fishmeal-based diet

An experimental culture of snubnose pompano, Trachinotus blochii was conducted for 210 days in low saline water to understand the growth potential in small indigenous Re-circulatory Aquaculture Systems (iRAS) using low cost fishmeal-based diet developed for pompano. In the present study, snubnose pompano has reached the marketable size (287.32±4.84 g) during the culture period with excellent feed conversion ratio of 1.74±0.01 and average daily growth of 1.32±0.02 g/day. Harvested fish showed viscerosomatic index, hepatosomatic index and intra-peritoneal fat ratio of 4.98±0.21, 0.99±0.09 and 1.45±0.16 %, respectively which enhanced the head-on muscle yield (80.57±3.25 %) and fillet yield (52.22±2.27 %). The survival percentage of T. blochii reared in the iRAS was 88.89±3.51 %. The cost of the diet developed for snubnose pompano is well below the commercially available marine fish feeds. The present study suggested that snubnose pompano can be successfully cultured in low saline sea water iRAS using low cost fishmeal-based diet.

Effect of Feeding Rate on Survival, Zootechnical Performance of Tilapia Oreochromis niloticus (Linnaeus, 1758) Brazil Strain Larvae Fed on 17-α-methyltestosterone Treated Feed

This study was conducted to evaluate the feeding levels on survival, growth performance and feed utilization in the Brazil strain of Nile tilapia Oreochromis niloticus. Four (4) batches of larvae with mean initial weight 0.012 ± 0.005 g and mean initial total length 9 ± 0.003 mm were formed in triplicate, three per feeding rate. The rationing rates according to fry biomass applied in this trial were: batch 1: 50, 40, 30 and 25%, batch 2: 40, 30, 25 and 20%, batch 3: 30, 25, 20 and 18% and batch 4: 25, 20, 18 and 15% of biomass. The different feeding rates were tested during the 1st, 2nd, 3rd and 4th week of larval rearing respectively. The fish were all fed a commercial feed (48% protein) distributed manually at a frequency of 5 meals per day. After 28 days of rearing, the results show that apart from the survival rate, the other parameters such as final average weight, daily growth and food consumption index were affected by the different rationing rates tested. The larvae of batch 2 rationed at 40, 30, 25 and 20 % of their biomass during the 1st, 2nd, 3rd and 4th week of rearing respectively recorded significantly higher growth parameters (MWF: 1.092±0.027 g and DG: 0.038±0.000 g) and a more interesting food converion ratio (0.88 ) than the other batches of fry. From this study, it is concluded that an optimal feeding rate of 40, 30, 25 and 20% of the larval biomass during the 1st, 2nd, 3rd and 4th week of rearing, respectively, should be applied in order to avoid either wastage or underfeeding of the subjects during hormone treatment with 17 α-methyltestosterone.

Effects of light source and photoperiod on growth of duckweed Landoltia punctata and its water quality

This study investigated the effects of light source [LED white (LW), fluorescent white (T5) and LED blue (LB)] and photoperiod (12:12, 16:08, 24:00 light/dark) on growth of duckweed Landoltia punctata and the resulting effects on its water quality for 16 days. The average daily relative growth rate (RGR) reached about 0.519 g d−1. Both light source and photoperiod had no significant difference on the mean RGR; however, their interaction had significant effects on duckweed's growth (p ≤ 0.05). Moreover, except T5 (24:00) > [T5 (12:12) ≥ T5 (16:08) ≥ LB (24:00)], LW (12:12) > [T5 (16:08) ≥ LB (24:00)], and LB (12:12) > LB (24:00), there were no differences in RGR in all pair-comparisons of treatment (p ≤ 0.05). Nitrate (NO3−) mostly influenced weight increment (WI), 70%. For light source and photoperiod effects on water quality, no total ammonia nitrogen (TAN) was detected in all treatments after 16 days, while NO3− increased gradually. In addition, results show that most of the total nitrogen (TN) was contributed from NO3− (R2 = 0.9999). Overall, our findings could contribute on producing duckweed in a controlled and programmed condition for maximum production and quality. Constructed models and practical application contribute in predicting nutrients sensitivity and proven useful in water management or water quality assessments.