Developing a dynamic yield and growth model for maize under various water and nitrogen regimes

Better irrigation and nitrogen (N) scheduling and more efficient management of crop production require modeling of plant growth and crop yield. Models become more applicable if they are simple and require less and accessible inputs. The objective of this study was to use simple equations of soil water budget, evapotranspiration (ET), leaf area index (LAI), yield, and harvest index (HI)–transpiration function to develop a model for the prediction of growth and yield of maize under various water and N rates. The model was calibrated based on given data under sprinkler irrigation and verified based on independent data under furrow irrigation. The comparison between predicted and measured values of different crop parameters did not show any significant difference and the model was able to estimate LAI, ET, soil water content, HI, dry matter, and grain yield properly. Furthermore, an equation was presented to predict daily dry matter accumulation by a logistic curve for different water and N applications. It was concluded that the presented simple model was able to predict crop yield quite well and hence could be used for farm irrigation and N scheduling and management of both. Furthermore, the relationship between LAI and ET may be different in various environmental conditions that should be considered in using the model.     

Genetic parameter estimates for postweaning traits of beef cattle in a stressful environment

Postweaning growth data, collected from a Hereford herd located in the Southwest, were used to estimate genetic parameters for weights and gains. The herd was maintained on unsupplemented range forage, and average weight losses from weaning to yearling age were 9% for bulls and 12% for heifers. Data were grouped into years with poor and good environments based on contemporary group means for gain from 8 to 12 mo. Postweaning growth data (12- and 20-mo weights, 8- to 12-mo gain and 12- to 20-mo gain) were analyzed by least squares methods with a model that included year of birth, sire within year of birth, age of dam and a covariate of age for 12- and 20-mo weights. Heritability estimates of 12- and 20-mo weights for bulls were .58 +/- .15 and .55 +/- .22 in good environments vs .32 +/- .11 and 1.09 +/- .15 in poor environments; for heifers these estimates were .19 +/- .08 and .35 +/- .12 in good environments vs .38 +/- .07 and .47 +/- .09 in poor environments. Heritability estimates of 8- to 12-mo and 12- to 20-mo gain for bulls were .32 +/- .14 and .51 +/- .24 in good environments vs .16 +/- .11 and .09 +/- .14 in poor environments; for heifers these estimates were .21 +/- .08 and .14 +/- .10 in good environments vs .10 +/- .06 and .44 +/- .10 in poor environments. Genetic correlations among the preweaning traits of birth and weaning weight and postweaning weight traits were positive and of a moderate to large magnitude, with the exception of birth and 12-mo weight in a poor environment (-.06 +/- .49). Genetic correlations between 8- to 12-mo gain and birth weight in poor environment and weaning weight in all environments were negative (range from -.06 +/- .33 to -.53 +/- .41). Genetic correlations among 12- and 20-mo weights were large and positive in all environments. Relationships among gains were more variable.     

Targeted Deletion of Los1 Homologue Affects the Production of a Recombinant Model Protein in Pichia pastoris

Background:The methylotrophic yeast Pichia pastoris is an appealing production host for a variety of recombinant proteins, including biologics. In this sense, various genetic- and non-genetic-based techniques have been implemented to improve the production efficiency of this expression platform. Los1 (loss of supression) encodes a non-essential nuclear tRNA exporter in Saccharomyces cerevisiae, which its deletion extends RLS. Herein, a los1-deficient strain of P. pastoris was generated and characterized. Methods:A gene disruption cassette was prepared and transformed into an anti-CD22-expressing strain of P. pastoris. A δ los1 mutant was isolated and confirmed. The drug sensitivity of the mutant was also assessed. The growth pattern and the level of anti-CD22 ScFv expression were compared between the parent and mutant strains.Results:The los1 homologue was found to be a non-essential gene in P. pastoris. Furthermore, the susceptibility of los1 deletion strain to protein synthesis inhibitors was altered. This strain showed an approximately 1.85-fold increase in the extracellular level of anti-CD22 scFv (p < 0.05). The maximum concentrations of total proteins secreted by δ los1 and parent strains were 125 mg/L and 68 mg/L, respectively.Conclusion:The presented data suggest that the targeted disruption of los1 homologue in P. pastoris can result in a higher expression level of our target protein. Findings of this study may improve the current strategies used in optimizing the productivity of recombinant P. pastoris strains. Key Words: Aging, Longevity, Pichia pastoris, Recombinant proteins     

Effects of dietary administration of Echinacea purpurea on growth indices and biochemical and hematological indices in rainbow trout (Oncorhynchus mykiss) fingerlings

This study was conducted to evaluate the effects of Echinacea purpurea (EP) on growth and some hematological and blood biochemical indices of rainbow trout fingerlings. A basal diet was supplemented with 0 (control), 0.25, 0.5, 1, and 2 g EP kg?1 to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish with an initial average weight of approximately 8 g. After 8 weeks of feeding trial, fish fed diets with 0.25 and 0.5 g EP kg?1 showed highest final weight and SGR and fish fed with the control diet indicated the lowest final weight and SGR. There was a significant (P < 0.05) decrease in FCR between the control group and the groups fed with diets of 0.25 and 0.5 g EP kg?1. Biochemical parameters such as serum total protein content, albumin content, globulin content, and albumin/globulin ratio in the fish were evaluated. There were significant differences between hematological parameters including RBC, WBC, HB, lymphocyte, and neutrophil percentage in fish fed with dietary nucleotide compared with control treatment (P < 0.05). The results suggest that EP administration at 0.25 and 0.5 g EP kg?1 exerted positive effects on growth and biochemical and hematological indices in rainbow trout.     

Effect of dietary willow herb,Epilobium hirsutum extract on growth performance,body composition,haematological parameters and Aeromonas hydrophila challenge on common carp,Cyprinus carpio

The present study was conducted to evaluate the use of Epilobium hirsutum extract in diet of common carp, Cyprinus carpio (20 ± 2 g). Different levels of plant extract (0%, 0.5%, 1, 3% and 3%+2‰ multivitamin (2 g of multivitamin per kg diet) were spread on commercial diet. The feed was offered by 8 weeks. Results showed that fish fed experimental diets had no significant difference (P>0.05) in specific growth rates, condition factor, feed conversion ratios and survival compared with control. There were no significant difference (P>0.05) in moisture, crude protein, crude lipid and ash content of common carp fed diets containing various levels of plant extract. The mortality of fish challenged by Aeromonas hydrophila have been recorded for 30 days after challenging, results showed that mortality decreased significantly (P<0.05) in fish fed diet containing plant extract compared with the control. The lowest mortality observed in group fed diet containing 3% plant extract. Haematological parameters showed that white blood cells had significantly (P<0.05) increased in infected and uninfected groups compared with the control. Red blood cells, haemoglobin and haematocrit had no significant change (P>0.05) in infected and uninfected groups compared with the control.     

Prevalence of thin-walled <Emphasis Type="Italic">Sarcocystis cruzi</Emphasis> and thick-walled <Emphasis Type="Italic">Sarcocystis hirsuta</Emphasis> or <Emphasis Type="Italic">Sarcocystis hominis</Emphasis> from cattle in Iran

Bovine sarcocystosis is caused by Sarcocystis cruzi and is known to cause considerable morbidity and mortality in cattle. This species is distributed worldwide in cattle and is the most prevalent of the Sarcocystis species infecting cattle. There is high infection rate of sarcocyst in cattle in Iran, but to our knowledge, there is no study about identification of Sarcocystis species. This work aimed to survey prevalence of S. cruzi cyst in slaughtered cattle of Isfahan, Iran. In this study, esophageal and diaphragmatic muscles of 100 cattle were collected from Fesaran abattoir of Isfahan and examined for the presence of Sarcocystis spp. cysts macroscopically and microscopically. No macroscopic sarcocysts were found in any of the samples. In light microscopy, 89 out of 100 cattle (89%) had thin-walled cysts of S. cruzi, while 21 out of them (21%) had thick-walled sarcocysts. In addition to light microscopy, ultrastructural features of the thin-walled cyst confirmed the presence of S. cruzi.     

Relationships among udder shape, udder capacity, cow longevity and calf weights

Udder capacity and udder shape were scored on 3- to 10-yr-old cows from a large Hereford herd. Udder capacity was scored from 1 (small) and 5 (large) and udder shape was scored from 1 (balanced, udder level with ground) to 5 (unbalanced, funnel-shaped udder). Data were analyzed within age of cow for udder capacity scores from 1 to 4 and for udder shape scores from 1 to 3 because of the limited number of observations in other categories. Year of birth of cow was a significant source of variation in both udder capacity and udder shape. Days in lactation (ranging from 81 +/- 23 d in 3-yr-old cows to 71 +/- 25 d in 4-yr-old cows) was an important source of variation for udder capacity; as lactation progressed udder capacity score declined. Body condition of the cow was an important source of variation for udder capacity in 3- and 4-yr-old cows; cows with more external body condition had larger udder capacity scores. The heritability estimates of udder capacity and udder shape for 3-yr-old cows were .12 +/- .14 and .15 +/- .16, respectively; the repeatability estimates of scores over years were .14 +/- .02 and .16 +/- .03, respectively. Residual correlations between udder capacity and udder shape were low, ranging from -.10 in 3-yr-old cows to .10 in 6-yr-old cows. Neither udder characteristic affected the number of years a cow remained in the herd, but cows with unbalanced udders had more udder defects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of factors affecting the availability of air bubbles to subsurface drip irrigation emitters during oxygation

In this study, we sought to define system features that impact air delivery in subsurface drip irrigation systems. A 58 % decrease in emitter cross-sectional area caused a 71 % reduction in the water flow rate, but the 37 % decrease in emitter air flow rate was statistically non-significant. For emitters with symmetric connectors, delivery of air from the emitters depended on the length of the connector relative to the air layer flowing at the top of the pipe. Emitters with asymmetric connectors yielded greater air flow rates compared to those with symmetric connectors, a result ascribed to a low-pressure region at the tip of asymmetric connectors. When symmetric connectors were used, an increase in pipe diameter was directly related to an increase in the uniformity of emitter air flow rate distribution expressed by the Christiansen uniformity coefficient (CUC), and inversely related to the efficiency of air bubble delivery and mean emitter air flow rate. In contrast, when asymmetric connectors were used, an increase in pipe diameter was associated with a decrease in CUC, and an increase in the efficiency of air bubble delivery and mean emitter air flow rate.