Growth performance,duodenal morphology and the caecal microbial population in female broiler chickens fed glycine-fortified low protein diets under heat stress conditions

1. This study was undertaken to examine the effect of feeding glycine (Gly)-fortified low protein (LP) diets on the growth performance, duodenal morphology and caecal microbial populations of broiler chickens raised under unheated, cyclic or constant heat stress environmental conditions.

2. From d 1 to 21 (starter phase), an equivalent number of birds were fed either a normal protein (NP) diet or a LP diet fortified with Gly. From d 22 to 42 (grower phase), an equivalent number of birds from each starter diet were distributed to one of the following dietary groups: (i) an NP diet during the starter and grower phases (NPNP), (ii) an NP diet during the starter phase and a LP diet during the grower phase (NPLP), (iii) an LP diet during the starter phase and an NP diet during the grower phase (LPNP) or (iv) LP diets during both phases (LPLP).

3. Commencing from d 22, an equivalent number of birds from each dietary group were exposed to (i) 23 ± 1°C throughout (unheated), (ii) 34 ± 1°C for 7 h each day from 10:00 to 17:00 (cyclic heat) or (iii) 34 ± 1°C throughout (constant heat).

4. Feeding the LP diet during the starter phase resulted in feed intake (FI), weight gain (WG), feed conversion ratios (FCR) and energy efficiency ratios (EER) similar to those for the NP diet. The birds fed the LP diet had a significantly higher protein efficiency ratio (PER) compared with the birds fed the NP diet.

5. During the grower phase, there were significant diet × temperature interactions for F, WG, FCR, PER, EER, villus height, crypt depth and caecal Clostridia. The birds fed the NPLP and LPLP diets had lower FI, WG and EER, higher FCR, shorter villus height and crypt depth and higher caecal Clostridia compared with the birds fed LPNP and NPNP diets under constant heat stress. However, feeding birds the NPLP and LPLP diets resulted in FI, WG, EER, FCR, morphology parameters and caecal Clostridia equivalent to the birds fed LPNP and NPNP diets, as well as improved PER, under unheated and cyclic heat stress conditions.

6. In conclusion, our results indicate that Gly-fortified LP diets can be fed to broilers under normal and acute heat stress environmental conditions without any adverse effects on performance. However, the use of such LP diets can be detrimental to broilers under chronic heat stress conditions.     

Manganese Mobility in Egyptian Soils as affected by Inoculation with Manganese Reducing Organisms

The capacity of three active Mn(IV)-reducing isolates to dissolve Mn in sterilized samples of two Egyptian soils and a pure sand enriched with MnO₂ were studied. These isolates were identified as Penicillium variable (P. v.), Aspergillus niger (A. n.) and Streptomyces exfoliatus (S. e.). The data indicated that inoculation with the fungi and actinomycete mentioned increased the soil contents of water soluble + exchangeable manganese (Mn_ws+ex) but decreased the easily reducible form (Mn_er). The increase in Mn-mobility depended on soil type, organism used and time of incubation. The maximum level of Mn_ws+ex appeared after 14 days in the 3 soil samples. The release of Mn (II) ranged from 19.6 to 49.4 ppm in the sand samples, from 34.8 to 53.3 ppm in samples of a clay loam soil and from 9.9 to 19.8 ppm in samples of a calcareous sandy loam soil. The increase in Mn_ws+ex was at the expense of Mn_er but not in stochiometric amounts. The organisms tested can be ranked according to their capacity to reduce MnO₂ in the following order (for all soils) Streptomyces exfoliatus > Aspergillus niger > Penicillium variable. Statistical analysis of the data revealed significant differences due to inoculation, soil type, incubation time and their interactions.     

The 18O/16O and 17O/16O ratios in atmospheric nitrous oxide: A mass-independent anomaly

Measurements of the oxygen isotope ratios (18O/16O and 17O/16O) in atmospheric nitrous oxide (N2O) from La Jolla, Pasadena, and the White Mountain Research Station (elevation, 3801 meters) in California and the White Sands Missile Range in New Mexico show that N2O has a mass-independent composition. These data suggest the presence of a previously undefined atmospheric process. The La Jolla samples can be explained by a mixing between an atmospherically derived source of mass-independent N2O and biologically derived mass-dependent N2O. Possible origins of the mass-independent anomaly in N2O are discussed.     

Interactive effects of biochar and polyacrylamide on decomposition of maize rhizodeposits: implications from <Superscript>14</Superscript>C labeling and microbial metabolic quotient

Purpose

The applications of biochar (BC) and polyacrylamide (PAM) may have interactive effects on carbon (C) dynamics and sequestration for improving the soil quality and achieving sustainable agriculture. Relative to BC and PAM, rhizodeposits act as C and energy source for microorganisms and may change the mineralization dynamics of soil organic matter (SOM). No attempt has been made to assess the effects of BC, anionic PAM, or their combination on the decomposition of different aged ¹⁴C-labeled rhizodeposits. The objective of this study was to investigate the effects of the treatments mentioned above on the decomposition of different aged ¹⁴C-labeled maize rhizodeposits.

Materials and methods

biochar (BC) at 10 Mg ha^?1 or anionic PAM at 80 kg ha^?1 or their combination (BC + PAM) was applied to soils with/without 2-, 4-, 8-, and 16-day-aged ¹⁴C-labeled maize rhizodeposits. After that, the soil was incubated at 22 °C for 46 days.

Results and discussion

After 2 days of incubation, the total CO₂ efflux rates from the soil with rhizodeposits were 1.4–1.8 times higher than those from the soil without rhizodeposits. The cumulative ¹⁴CO₂ efflux (32 % of the ¹⁴C input) was maximal for the soil containing 2-day-aged ¹⁴C-labeled rhizodeposits. Consequently, 2-day-aged rhizodeposits were more easily and rapidly decomposed than the older rhizodeposits. However, no differences in the total respired ¹⁴CO₂ from rhizodeposits were observed at the end of the incubation. Incorporation of ¹⁴C into microbial biomass and 66–85 % of the ¹⁴C input remained in the soil after 46 days indicated that neither the age of ¹⁴C-labeled rhizodeposits nor BC, PAM, or BC + PAM changed microbial utilization of rhizodeposits.

Conclusions

Applying BC or BC + PAM to soil exerted only minor effects on the decomposition of rhizodeposits. The contribution of rhizodeposits to CO₂ efflux from soil and MBC depends on their age as young rhizodeposits contain more labile C, which is easily available for microbial uptake and utilization.

     

Significance of sulfur in heat stressed cluster bean (Cymopsis tetragonoloba L. Taub) genotypes: responses of growth,sugar and antioxidative metabolism

A sand culture experiment was carried out to study the effects of sulfur deprivation on heat stress tolerance of two cluster bean (Cymopsis tetragonoloba L. Taub) cultivars (GC-1 and Pusa Nau Bahar (PNB)). Three weeks old sulfur-starved and sulfur-supplemented plants were subjected to heat stress (45°C/35°C) treatment for 24 h. Total dry weight, chlorophyll content, Chlorophyll a:b ratio, electrolyte leakage, malondialdehyde (MDA) accumulation, H₂O₂ content, sugar, glucose-6-phosphate (G-6-P), fructose-6-phosphate (F-6-P), ascorbate and glutathione concentrations and antioxidant enzyme activity (superoxide dismutase (SOD) and catalase (CAT)) were monitored, at the end of the heat stress treatment. Heat stress enhanced and sulfur starvation depleted the contents of sugar metabolites, but the accumulation of sugar, G-6-P and F-6-P were not related with heat stress tolerance. Antioxidant enzyme activities of SOD and CAT were influenced significantly more by sulfur starvation than heat stress. The results showed that under heat stress, the addition of sulfur helps to mitigate the oxidative damage in both the cultivars. However, GC-1 was more heat tolerant as it was characterized by significantly higher total dry weight, chlorophyll content, ascorbate and glutathione content and lower H₂O₂, MDA, electrolyte leakage than PNB.