Effects of feeding rates on growth and production of Nile tilapia, common carp and silver carp polycultured in fertilized ponds

Abstract In an attempt to identify appropriate feeding rates for multispecies of fish raised in fertilized earthen ponds, the present work was conducted over a 19‐week experimental period to establish the growth performance, production and body composition of Nile tilapia, common carp and silver carp fed 0.0%, 0.5%, 1.0%, 3.0%, 5.0% biomass and to apparent satiation (treatments). Twelve ponds were stocked with a similar number and weight of each fish species. Two ponds were assigned to each of the treatments, and a 25% protein pelleted fish feed was used to feed fish at the specified rate of feeding. At the end of the experiment, growth, weight gain, survival, yield and body composition of fish groups were affected by the treatments. The economic effectiveness also varied among treatments. The most conspicuous attribute of the feeding rates was its lack of influence on growth (g day^?1), weight gain (g per fish), yield (kg ha^?1) or body composition of silver carp. The results of whole‐body proximate analysis indicated that various feeding rates had either an irregular pattern or no effects on the protein and ash gain per 100 g of fish body weight (bw) gain. The most notable exceptions were significant (P < 0.05) increases in body fat and gross energy gains in Nile tilapia, common carp and silver carp accompanied by decreases in percentages of moisture (but not in silver carp) as feeding rate increased. Among the six different feeding levels, feeding to apparent satiation (feed amount was equivalent to 2.67% of fish bw day^?1) appeared to be optimal, as it significantly (P < 0.05) supported the highest fish production, income and net profit compared with all other treatments except for the 3% feeding level, for which the differences in those measurements were comparable.     

Contrasted optimal environmental windows for both sardinella species in Senegalese waters

We investigate Sardinella aurita and Sardinella maderensis recruitment success relative to the variability of oceanographic conditions in Senegalese waters using generalized additive models (GAM). Results show that recruitment of both species is marked by a strong intra‐annual (seasonal) variation with minimum and maximum in winter and summer, respectively. Their interannual variations are synchronous until 2006 (recruitment decreasing), while from 2007 there is no synchrony. The model developed shows that sardinella recruitment variability is closely related to the tested environmental variables in the study area. However, the key environmental variables influencing the recruitment success are different for both species: the Coastal Upwelling Index and the sea surface temperature for S. aurita and S. maderensis, respectively. We report that recruitment success of S. aurita and S. maderensis are associated with distinct ranges of sea surface temperature, upwelling intensity, wind‐induced turbulence, concentration of chlorophyll‐a and north Atlantic oscillation index. Considering food security and socio‐economic importance of both stocks, we recommend that consideration is given to the environmental variability in the small pelagic fish national management plans, particularly in the context of climate change.     

Arbuscular mycorrhizal fungi improve the growth and phosphorus uptake of mung bean plants fertilized with composted rock phosphate fed dung in alkaline soil environment

Abstract

Inoculation effect of arbuscular mycorrhizal fungi (AMF) on phosphorus (P) transfer from composted dung of cattle with a diet supplemented with powdered rock phosphate (RP) and their successive uptake by mung bean plants was assessed in alkaline soil. The efficacy of composted RP fed dung alone or/and in combination with AMF inoculums containing six different species were compared with SSP in six replicates per treatment in pots. The results showed that the association of AMF with composted RP fed dung had a positive effect on mung bean shoot (3.04?g) and root (2.62?g) biomass, chlorophyll (a, b), carotenoid contents and N (58.38?mg plant^?1) and P (4.61?mg plant^?1) uptake. Similarly, the percent roots colonization (56%) and nodulation of mung bean plant roots and their post-harvest soil properties were also improved by the inoculation of AMF together with composted RP fed dung. It is concluded that the combined application of AMF with composted RP fed dung has almost the same effect as SSP for improving mung bean plants growth and their nutrients uptake. Moreover, AMF inoculants can be used as a suitable biofertilizer in combination with locally available organic sources of fertilizers for improving P status and growth of plants in alkaline soils.     

Tuna viscera protein hydrolysate: nutritive and disease resistance properties for Persian sturgeon (Acipenser persicus L.) larvae

The effect of fish protein hydrolysate (FPH) on the growth, feed utilization, digestive enzymes, gut microflora and resistance to bacterial challenge in Persian sturgeon (Acipenser persicus) larvae during a 45‐day feeding trial has been investigated. Artificial diets containing different levels of tuna visceral protein hydrolysate (PH0, PH10, PH25 and PH50) and live foods (Artemia: 5 days, Daphnia: 40 days) were fed to Persian sturgeon larvae. Larvae fed on the PH10 and PH25 had growth, feed utilization, protein content and trypsin activity significantly better than PH0 and PH50 groups (P < 0.05). Condition factors, survival rate and pepsin activity were not significantly different (P > 0.05). Brush border membrane enzymes to cytosolic enzyme ratio revealed that maturation had been occurred in 41 days post hatch (dph) at moderate FPH levels. In 54 dph larvae, this ratio was not affected by the level of FPH in the diet. No significant differences were observed in the total number of gut microflora or in the resistance to Aeromonas hydrophila (P > 0.05), whereas lactic acid bacteria was significantly higher in PH50 (P < 0.05). The results of this study show that application of moderate levels of FPH in Persian sturgeon diets could enhance larvae performance due to the early maturation in intestinal.     

Agronomic traits at the seedling stage,yield, and fiber quality in two cotton (Gossypium hirsutum L.) cultivars in response to phosphorus deficiency

ABSTRACT

Cotton is critical for phosphorus demands and very sensitive for its deficiency. However, identifying the effect of low-phosphorus tolerance on cotton growth, yield, and fiber quality by reducing phosphorus consumption. This may help to develop phosphorus-tolerant high-yielding cotton cultivars. In a two-year repeated (2015 and 2016) hydroponic experiment (using 0.01 and 1 mM KH₂PO₄), two cotton cultivars with phosphorus sensitivity (Lu 54; a low-phosphorus sensitive and Yuzaomian 9110; a low-phosphorus tolerant) were screened on the base of agronomic traits and physiological indices through correlation analysis, cluster analysis and principal component analysis from 16 cotton cultivars. Low phosphorus nutrition reduced the plant height, leaf number, leaf area, phosphorus accumulation and biomass in various organs of seedlings. The deficiency negatively affected the morphogenesis of seedlings, as well as yield and fiber quality. Further, these screened cultivars were tested in a pot experiment with 0, 50, 100, 150, 200 kg P₂O₅ ha^?1 during 2016 and 2017. It was found to have a significant (P< 0.05) difference in boll number, lint yield, fiber strength, and micronaire at the harvest. Furthermore, after collectively analyzed the characteristics of Lu 54 and Yuzaomian 9110, there were six key indices that could improve the low phosphorus tolerance of cotton cultivars. These were root phosphorus accumulation, stem phosphorus accumulation percentage, leaf and total biomass of seedlings, seed cotton weight per boll and fiber length.     

Follicular dynamics and changes in oestradiol‐17β, progesterone and LH profiles following PGF2α induced oestrus in early and late ovulating Beetal goats

This study compares the factors associated with variable interval to oestrus and ovulation between early versus late ovulating goats following PGF_2α administration. The time of ovulation in Beetal goats (n = 38) was monitored through transrectal ultrasound at every 6 hr following a single dose of PGF_2α (experiment 1). Variations in oestrus and ovulation times were further explored through the changes in follicular dynamics, endocrine profiles and behaviour in another set of goats (n = 13) following single PGF_2α given randomly during the luteal phase (experiment 2). The ovulation time varied between 60 and 96 hr, and 57% of ovulations occurred by 72 hr following PGF_2α (experiment 1). Accordingly, the goats (n = 13) in the second experiment were retrospectively divided either into early and/or late ovulating, that is, ≤72 and/or ≥84 hr following PGF_2α. The onset of oestrus, peak estradiol‐17β concentration and LH surge after PGF_2α was first observed in early than late ovulating goats (p < 0.05). The goats ovulating early had larger follicle and smaller CL in diameter at the time of PGF_2α administration than those ovulating late (5.4 ± 0.2 vs. 4.3 ± 0.2 mm and 10 ± 0.6 vs. 11.8 ± 0.3 mm, respectively; p < 0.05). Likewise, plasma progesterone concentration tended to be lower (p = 0.087) in early than late ovulating goats. In conclusion, the size of dominant follicle and CL at the time of PGF_2a determines the interval to ovulation following a single dose of PGF_2a during the luteal phase.     

Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis

In ruminants, the ruminal epithelium not only has the function of absorbing nutrients but also is an important tissue to prevent harmful substances in the rumen from entering the blood circulation. Thus, the normal function of ruminal epithelium is critical for ruminants. However, subacute ruminal acidosis induced by high-concentrate diets often damages the barrier function of ruminal epithelium in ruminants. Recently, many studies have shown that dietary supplementation with thiamine is an effective method to alleviate subacute ruminal acidosis. In order to provide theoretical reference for the in-depth study of subacute ruminal acidosis and the application of thiamine in the future, this review introduces the effects of subacute ruminal acidosis on morphological structure, inflammatory response, and tight junction of ruminal epithelium. In addition, this paper summarizes the role of thiamine in maintaining ruminal epithelial function of ruminants during subacute ruminal acidosis challenge.     

Resource allocation tradeoffs in Manila’s peri-urban vegetable production systems: An application of multiple objective programming

This paper designed and developed a multi-objective programming (MOP) model to illustrate the dynamic relationship among technologies, productive activities, constraints and farmers’ objectives in the peri-urban vegetable production system and use the model as an economic tool in analysing probable consequences of a given action or innovation on the farm. The best compromise solution was generated using four analytical steps, as follows: single-objective optimization (to determine the ideal and anti-ideal values of the objective functions); constrained optimization (to generate the set of Pareto non-dominated solutions); cluster analysis (to trim down efficient set into smaller homogeneous groups); and compromise programming (to determine where the best compromise solution lies).