The aim of the present study was to investigate the effect of glutamine (Gln) on growth performance, biochemical parameters, and antioxidant capacity in broilers exposed to medium-term chronic heat stress. A total of 300 twenty-two-day-old Arbor Acres broilers (half male and female) were randomly divided into 5 groups. The control group was housed at normal temperature (24°C) and fed a basic diet; 4 heat-stressed groups were housed under cyclic high temperature (8 h at 34°C, 16 h at 24°C, daily) and fed the basic diet supplemented with 0, 0.5, 1.0, and 1.5% Gln, respectively. After 2 wk, broilers exposed to high temperature had significantly lower (P < 0.05) body weight (BW), body weight gain (BWG), feed intake (FI), serum total protein, glutathione (GSH), total superoxide dismutase (T-SOD) activity, and total antioxidant capacity (T-AOC), but higher (P < 0.05) feed-to-gain ratio (FGR), serum glucose, and malondialdehyde (MDA). Dietary supplementation with 1.0 and 1.5% Gln significantly increased (P < 0.05) BW, BWG, FI, and serum TP, whereas dietary 1.5% Gln also significantly decreased (P < 0.05) FGR and serum glucose, compared to the heat treatment control group. Dietary supplementation with 1.0 and 1.5% Gln significantly decreased (P < 0.05) serum MDA, but significantly increased (P < 0.05) serum GSH, T-SOD activity, and T-AOC compared to the heat treatment control group. This study suggests that dietary Gln improves growth performance, serum biochemical profile, and antioxidant capacity in heat-stressed broilers.
Abstract Understanding the effect of land use on soil carbon, nitrogen, and microbial activity associated with aggregates is critical for thorough comprehension of the C and N dynamics of karst landscapes/ecosystems. We monitored soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC), and C mic : C org ratio in large macro- (>2 mm), small macro- (0.25–2 mm), and micro- (0.053–0.25 mm) aggregates to determine the changes in soil properties under different land uses in the karst area of Southwest China. Five common land-use types—enclosure land (natural system, control), prescribed-burning land, fuel-wood shrubland, pasture and maize fields—were selected. Results showed that pasture and maize fields remarkably decreased the SOC and TN concentrations in aggregates. Conversion of natural system to other land uses decreased MBC (except for prescribed-burning) and increased C mic : C org ratios in aggregates. The extent of the response to land uses of SOC and TN concentrations was similar whereas that of MBC and C mic : C org ratios differed across the three aggregate sizes. Further, the SOC concentrations were significantly higher in macro-aggregates than micro-aggregates; the MBC and C mic : C org ratios were highest in small macro-aggregates. Therefore, small macro-aggregates might have more active C dynamics.
Tillage leads to rapid loss of soil nitrogen (N) over a short period of time in karst areas. N leaching is the primary pathway of soil N loss and therefore is key to understanding the mechanisms of N loss induced by tillage. However, the factors affecting N leaching under tillage are not fully understood. Effects of tillage at various frequencies on leached N were examined in a one-year in situ simulation experiment using five tillage treatments: no tillage (T0), semiannual tillage (T1), and tillage every four months (T2), two months (T3), and monthly (T4). Concentration and amount of leached N had peaks in dry–rewetting months. Tillage significantly increased total amounts of leached N during the one-year experiment, and the largest amount of leached N was under tillage at the highest frequency. The primary form of N in leachate was NO3¯ (88.49–91.11%), followed by DON (7.80–9.87%), and then NH4+ with the lowest amount (1.09–2.10%). Tillage increased the amount of leached NO3¯ and DON, but had no significant effect on leached NH4+. Additionally, the amount of leached N had significantly negative correlations with 5–8 mm soil aggregate, NO3¯, DON, and sand content, and positive correlations with 2–5 and 0.25–2 mm. Soil 5–8 mm aggregate and DON were the main factors explaining the variation in leached N according to the RDA analysis. Tillage increased the breakdown of large aggregates, appearing to have increased the mineralization of organic matter, which resulted in increased N leaching. Our results emphasize the importance of reducing or eliminating physical disturbance indued by tillage and maintenance of large soil aggregates for decreasing N leachate in lime soil of karst regions.
The Musca domestica is a serious hygienic pest of poultry, humans, and livestock facilities with the immense ability for resistance development against chemical insecticides.The current study aimed to evaluate the susceptibility and resistance status of M. domestica against different classes of insecticides.For this purpose, adult M. domestica populations were collected from five different localities of Sargodha division (Sargodha, Khushab, Jauharabad, Mianwali, and Bhakkar), Punjab, Pakistan, and tested against selected insecticides.The resistance ratios (RR) at LC 50 ranged from 10.32-35.37 folds for deltamethrin, 17.49-38.13folds for fipronil, and 10.70-18.81folds for chlorpyrifos.The RR values at LC 50 for imidacloprid and pyriproxyfen ranged from 4.35-28.0and 10.56-21.45folds, respectively.The study showed varying levels of resistance in M. domestica populations from area to area and from insecticide to insecticide.Therefore, to control resistance development in M. domestica from livestock facilities, inappropriate and excessive use of insecticides must be controlled through proper mechanisms and strategies.
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