Energy Partitioning and Latent Heat Flux Driving Factors of the CAM Plant Pineapple (Ananas comosus (L.) Merril) Grown in the South Subtropical China

Elucidation of different vegetation energy partitioning and environmental control factors at the agro-ecosystem levels is critical for better understanding and scientific management of farmland. Pineapple (Ananas comosus (L.) Merril) is a tropical plant widely cultivated in the southern subtropical region of China; however, the energy partitioning of crassulacean acid metabolism (CAM) plants like pineapple and their interactions with the environment remain not well understood. In this study, we investigated the energy partitioning patterns of pineapple fields and latent heat flux (LET) response to environmental factors using the Bowen ratio energy balance system and meteorological observation field data. The results showed that the CAM plant pineapple energy partitioning was significantly different from the common C3 and C4 crops during the study period, which was mainly attributed to the complex interactions between CAM plant transpiration and the environment. Specifically, sensible heat flux was the main component of net radiation (Rn), followed by the LET, accounting for 65.0% and 30.8% of the Rn, respectively. Soil heat flux accounts for a very small fraction (4.2%). The mean values of the Bowen ratio were 2.09 and 1.41 for sunny and cloudy days during the daytime and 0.74 and 0.46 at night, respectively. LET is a key factor in responding to crop growth status and agricultural water management, and the path analysis indicates that its variation is mainly influenced directly by Rn with a direct path coefficient of 0.94 on sunny days, followed by vapor pressure deficit, air temperature and relative humidity, which indirectly affect LET through the Rn pathway, whereas soil moisture and wind speed have a low effect on LET. On cloudy days, the effect of Rn on LET was overwhelmingly dominant, with a direct path coefficient of 0.91. The direct path coefficients of the remaining factors on LET were very small and negative. Overall, this study is an important reference for enhancing the impact of pineapple as well as CAM plants on the surface energy balance and regional climate.

Effects of a phytogenic feed additive on weaned dairy heifer calves subjected to a diurnal heat stress bout

The study objective was to evaluate the effects of a phytogenic feed additive (PFA) on dry matter intake (DMI), average daily gain (ADG), inflammation, and oxidative stress markers of heifer calves exposed to a heat stress bout in the summer. A total of18 Holstein and 4 Jersey heifer calves (192 ± 5 kg of body weight at 162 ± 16 d of age) housed in indoor stalls were assigned to 1 of 2 dietary treatments (n = 11; 9 Holstein and 2 Jersey): (1) a basal total mixed ration (CTL), and (2) CTL top-dressed with 0.25 g/d of PFA. Following 7 d of acclimation, baseline measurements were made over 7 d under regular summer conditions [average temperature-humidity index (THI) = 79 from 0900 to 2000 h, and 75 from 2000 to 0900 h]. Calves were then subjected to a 7-d cyclic heat stress bout (HS) by turning on barn heaters and increasing the barn temperature to 33.0°C only during the daytime (the average THI = 85 from 0900 to 2000 h). The study continued for an extra 4-d period after HS ended (post-HS). The HS increased rectal temperature, skin temperature, and respiration rate from the baseline by 1.0°C, 4.0°C, and 49 breaths/min, respectively. The drinking water intake increased by 32% in response to HS, and calves continued to consume more water (44%) than the baseline consumption even after HS ended. The treatment × time interactions were not significant for feed intake, ADG, partial pressure of O2 in the blood, and blood concentrations of inflammation markers such as haptoglobin and lipopolysaccharide binding protein (LBP), and antioxidant markers such as protein carbonyl and thiobarbituric acid (TBARS). The PFA tended to increase daytime DMI (0.24 kg/d) compared with CTL throughout the experiment but did not affect ADG, which decreased from 1.12 kg/d to 0.26 kg/d in response to HS. Both DMI (13%) and ADG (85%) increased during post-HS relative to baseline, indicating compensatory performances that were not affected by the PFA. Serum haptoglobin and plasma LBP concentrations of PFA calves were 44% and 38% lower than that of CTL calves across all time points. The PFA decreased O2 pressure and tended to decrease protein carbonyl concentration in the blood across all time points. The PFA tended to decrease TBARS concentration on the first day of HS and increase and decrease the ratio of reduced to oxidized glutathione in the blood during the baseline and post-HS periods, respectively. Despite the lack of growth improvements, feeding PFA seems to increase O2 levels in the blood and alleviate oxidative stress and inflammation of heifer calve exposed to diurnal heat waves (~7 d) in the summer.

Symposium review: The impact of absorbed nutrients on energy partitioning throughout lactation

Most nutrition models and some nutritionists view ration formulation as accounting transactions to match nutrient supplies with nutrient requirements. However, diet and stage of lactation interact to alter the partitioning of nutrients toward milk and body reserves, which, in turn, alters requirements. Fermentation and digestion of diet components determine feeding behavior and the temporal pattern and profile of absorbed nutrients. The pattern and profile, in turn, alter hormonal signals, tissue responsiveness to hormones, and mammary metabolism to affect milk synthesis and energy partitioning differently depending on the physiological state of the cow. In the fresh period (first 2 to 3 wk postpartum), plasma insulin concentration and insulin sensitivity of tissues are low, so absorbed nutrients and body reserves are partitioned toward milk synthesis. As lactation progresses, insulin secretion and sensitivity increase, favoring deposition instead of mobilization of body reserves. High-starch diets increase ruminal propionate production, the flow of gluconeogenic precursors to the liver, and blood insulin concentrations. During early lactation, the glucose produced will preferentially be used by the mammary gland for milk production. As lactation progresses and milk yield decreases, glucose will increasingly stimulate repletion of body reserves. Diets with less starch and more digestible fiber increase ruminal production of acetate relative to propionate and, because acetate is less insulinogenic than propionate, these diets can minimize body weight gain. High dietary starch concentration and fermentability can also induce milk fat depression by increasing the production of biohydrogenation intermediates that inhibit milk fat synthesis and thus favor energy partitioning away from the mammary gland. Supplemental fatty acids also impact energy partitioning by affecting insulin concentration and insulin sensitivity of tissues. Depending on profile, physiological state, and interactions with other nutrients, supplemental fatty acids might increase milk yield at the expense of body reserves or partition energy to body reserves at the expense of milk yield. Supplemental protein or AA also can increase milk production but there is little evidence that dietary protein directly alters whole-body partitioning. Understanding the biology of these interactions can help nutritionists better formulate diets for cows at various stages of lactation.

Effect of voluntary waiting period on metabolism of dairy cows during different phases of the lactation

An extended calving interval (CInt) by extending the voluntary waiting period (VWP) could be associated with altered metabolism in dairy cows. The aim of this study was first to evaluate the effects of VWP on metabolism and body condition during the first 305 d after the first calving in the experiment (calving 1), around the end of the VWP, and during pregnancy (280 d before calving 2). Second, the effects of the VWP on metabolism were determined from 2 wk before until 6 wk after calving 2. Third, individual cow characteristics were used to predict milk production and body condition of cows after different VWP. Holstein-Friesian cows (N = 154, 41 primiparous [PP], 113 multiparous [MP]) were blocked for parity, milk production, and lactation persistency, randomly assigned to a VWP of 50, 125, or 200 d (VWP50, VWP125, or VWP200) and followed from calving 1 until 6 wk after calving 2. In the first 6 wk after calving 1 and from 2 wk before until 6 wk after calving 2, weekly plasma samples were analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate, glucose, insulin, and insulin-like growth factor 1 (IGF-1). From wk 7 after calving 1 until 2 wk before calving 2, insulin and IGF-1 were analyzed every 2 wk. Fat- and protein-corrected milk (FPCM) and body weight (BW) gain were measured weekly. Cows were divided in two parity classes based on calving 1 (PP and MP) and remained in these classes after calving 2. During pregnancy, MP cows in VWP200 had greater plasma insulin and IGF-1 concentration and lower FPCM compared with MP cows in VWP125 (insulin: 18.5 vs. 13.9 µU/mL, CI 13.0-19.7, P < 0.01; IGF-1: 198.5 vs. 175.3 ng/mL ± 5.3, P = 0.04; FPCM: 22.6 vs. 30.0 kg/d ± 0.8, P < 0.01) or VWP50 (insulin: 15.8 µU/mL, P < 0.01; IGF-1: 178.2 ng/mL, P < 0.01; FPCM: 26.6 kg/d, P < 0.01) and had a greater daily BW gain compared with cows in VWP50 (3.6 vs. 2.5 kg/d ± 0.2; P < 0.01). After calving 2, MP cows in VWP200 had greater plasma NEFA concentration (0.41 mmol/liter) compared with MP cows in VWP125 (0.30 mmol/liter, P = 0.04) or VWP50 (0.26 mmol/liter, P < 0.01). For PP cows, the VWP did not affect FPCM or body condition during the first lactation in the experiment, or metabolism after calving 2. Independent of the VWP, higher milk production and lower body condition before insemination were associated with higher milk production and lower body condition at the end of the lactation. Variation in these characteristics among cows could call for an individual approach for an extended VWP.

A New Quantitative Gait Analysis Method Based on Oscillatory Mechanical Energies Measured near Body Center of Mass

Human locomotion involves the modulation of whole-body mechanical energy, which can be approximated by the motion dynamics at the body’s center of mass (BCOM). This study introduces a new method to measure gait efficiency based on BCOM oscillatory kinetic energy patterns using a single inertia measurement unit (IMU). Forty-seven participants completed an overground walk test at a self-selected speed. The average oscillatory energy (OE) at BCOM during walking was derived from measured acceleration data. The total OE showed a positive correlation with forward-walking velocity. The ratio of total OE to constant forward kinetic energy for healthy adults varied from ~1−5%, which can be considered the percent of oscillatory energy required to maintain gait posture for a given forward-walking velocity. Mathematically, this ratio is proportional to the square of the periodic peak-to-peak displacement of BCOM. Individuals with gait impairments exhibited a higher percentage of oscillatory energy, typically >6%. This wearable IMU-based method has the potential to be an effective tool for the rapid, quantitative assessment of gait efficiency in clinical and rehabilitation settings.

Metabolic and hormonal control of energy utilization and partitioning from early to mid lactation in Sarda ewes and Saanen goats

In a recent study, we observed that starch-rich diets used in mid lactation induced lower milk production persistency and higher body fat accumulation in dairy ewes compared with dairy goats. Because these species differences could be linked to hormonal mechanisms that drive energy partitioning, in the same experiment, we explored the evolution of metabolic and hormonal status during lactation to test this hypothesis. Twenty mature Sarda dairy ewes and 20 mature Saanen goats [15-134 ± 11 d in milk (DIM), mean ± SD] were compared simultaneously. In early lactation, each species was allocated to one dietary treatment: high-starch diet [HS: 20.4% starch, on dry matter (DM) basis], whereas from 92 ± 11 DIM, each species was allocated to 1 of 2 dietary treatments: HS (20.0% starch, on DM basis) and low-starch (LS: 7.8% starch, on DM basis) diets. Blood samples were collected in the morning to analyze glucose, nonesterified fatty acids (NEFA), growth hormone (GH), insulin, and insulin-like growth factor I (IGF-I). Data were analyzed using the PROC MIXED procedure of SAS with repeated measurements (SAS Version 9.0). The HS and LS diets applied in mid lactation did not affect metabolic status of the animal within species; thus, only a comparison between species was carried out. From early to mid lactation, plasma glucose concentration was higher in ewes than in goats (54.57 vs. 48.35 ± 1.18 mg/dL), whereas plasma NEFA concentration was greater in goats than in ewes (0.31 vs. 0.25 ± 0.03 mmol/L). Goats had higher plasma GH concentration and lower plasma insulin content than ewes (4.78 vs. 1.31 ng/mL ± 0.47; 0.11 vs. 0.26 μg/L ± 0.02). Plasma IGF-I concentration did not vary between species. The comparison of metabolic and hormonal status of lactating Sarda dairy ewes and Saanen goats, carried out by studying simultaneously the 2 species in the same stage of lactation and experimental conditions, suggests that the higher insulin and glucose concentration observed in Sarda ewes explains why they partitioned more energy toward body reserves than to the mammary gland, especially in mid lactation. This can justify the negative effect of high-starch diets in mid-lactating Sarda ewes. Conversely, the highest GH and NEFA concentration observed in Saanen goats explain why they partitioned more energy of starch diets toward the mammary gland than to body reserves and justify the positive effect of high-starch diet in mid lactation. Together, these different responses contribute to explain why specialized dairy goats, such as the Saanen breed, have a higher milk production persistency than specialized dairy sheep breeds, such as the Sarda.

Review: Control of feed intake by hepatic oxidation in ruminant animals: integration of homeostasis and homeorhesis

Feed intake is controlled through a combination of long- and short-term mechanisms. Homeorhetic mechanisms allow adaptation to changes in physiological states in the long term, whereas homeostatic mechanisms are important to maintain physiological equilibrium in the short term. Feed intake is a function of meal size and meal frequency that are controlled by short-term mechanisms over the timeframe of minutes that are modulated by homeorhetic signals to adapt to changes in the physiological state. Control of feed intake by hepatic oxidation likely integrates these mechanisms. Signals from the liver are transmitted to brain feeding centers via vagal afferents and are affected by the hepatic oxidation of fuels. Because fuels oxidized in the liver are derived from both the diet and tissues, the liver is able to integrate long- and short-term controls. Whereas multiple signals are integrated in brain feeding centers to ultimately determine feeding behavior, the liver is likely a primary sensor of energy status.

Effects of high-starch or high-fat diets formulated to be isoenergetic on energy and nitrogen partitioning and utilization in lactating Jersey cows

The objective of this study was to determine the effects of high-starch or high-fat diets formulated to be isoenergetic on energy and N partitioning and utilization of energy. Twelve multiparous Jersey cows (mean ± standard deviation; 192 ± 11 d in milk; 467 ± 47 kg) in a crossover design with 28-d periods (24-d adaptation and 4-d collection) were used to compare 2 treatment diets. Treatments were high starch (HS; 30.8% starch, 31.8% neutral detergent fiber, and 1.9% fatty acids) or high fat (HF; 16.8% starch, 41.7% neutral detergent fiber, and 4.1% fatty acids). Diets were formulated to have net energy for lactation (NE_L) content of 1.55 Mcal/kg of dry matter according to the National Research Council (2001) dairy model. Nutrient composition was varied primarily by replacing corn grain in HS with a rumen-inert fat source and cottonseed hulls in HF. Gross energy content was lower for HS (4.43 vs. 4.54 ± 0.01 Mcal/kg of dry matter), whereas digestible (2.93 vs. 2.74 ± 0.035 Mcal/kg of dry matter) and metabolizable energy (2.60 vs. 2.41 ± 0.030 Mcal/kg of dry matter), and NE_L (1.83 vs. 1.67 ± 0.036 Mcal/kg of dry matter) content were all greater than for HF. Tissue energy deposited as body fat tended to be greater for HS (4.70 vs. 2.14 ± 1.01 Mcal/d). For N partitioning, HS increased milk N secretion (141 vs. 131 ± 10.5 g/d) and decreased urinary N excretion (123 vs. 150 ± 6.4 g/d). Compared with HF, HS increased apparent total-tract digestibility of dry matter (66.7 vs. 61.7 ± 1.06%), organic matter (68.5 vs. 63.2 ± 0.98%), energy (66.0 vs. 60.4 ± 0.92%), and 18-carbon fatty acids (67.9 vs. 61.2 ± 1.60%). However, apparent total-tract digestibility of starch decreased for HS from 97.0 to 94.5 ± 0.48%. Compared with HF, HS tended to increase milk yield (19.7 vs. 18.9 ± 1.38 kg/d), milk protein content (4.03 vs. 3.93 ± 0.10%), milk protein yield (0.791 vs. 0.740 ± 0.050 kg/d), and milk lactose yield (0.897 vs. 0.864 ± 0.067 kg/d). In addition, HS decreased milk fat content (5.93 vs. 6.37 ± 0.15%) but did not affect milk fat yield (average of 1.19 ± 0.09 kg/d) or energy-corrected milk yield (average of 27.2 ± 1.99 kg/d). Results of the current study suggest that the HS diet had a greater metabolizable energy and NE_L content, increased partitioning of N toward milk secretion and away from urinary excretion, and may have increased partitioning of energy toward tissue energy deposited as fat.

Level and source of fat in the diet of gestating beef cows: I. Effects on the prepartum performance of the dam and birth weight of the progeny1

A 2-yr study was conducted to evaluate the effects of level and source of fat in the diet of gestating beef cows on their prepartum performance and birth weight of progeny. Each year, 75 multiparous (≥3 calving) pregnant Angus cows were stratified by BW (663 ± 21.5 kg) and BCS (2.6 ± 0.12; 1 to 5 scale) and randomly assigned to 1 of 15 outdoor pens. Subsequently, each pen was randomly assigned to 1 of 3 (n = 5) treatments: a low-fat diet (LF; 1.4 ± 0.12% EE) consisting of grass-legume hay, barley straw, and barley grain, or 1 of 2 high-fat diets (HF; 3.3 ± 0.20% EE) that included either a canola seed (CAN) or a flaxseed (FLX) based pelleted feed. Diets were formulated to meet the requirements of pregnant beef cows during the last 2 trimesters of gestation (0.183 ± 4.8 d), adjusted for changes in environmental conditions, and offered such that each pen on average received similar daily amounts of DE (31.2 ± 2.8 Mcal/cow), CP (1.36 ± 0.13 kg/cow), and DM (12.9 ± 1.0 kg/cow). Data were analyzed as a randomized complete block design with contrasts to separate the effects of level (LF vs. HF) and source (CAN vs. FLX) of fat. After 160 d on trial, conceptus corrected-BW (CC-BW) of LF cows (708 kg) and the proportion of overconditioned cows (13.2%) were greater (P ≤ 0.04) than those of HF, with no difference (P ≥ 0.84) between CAN and FLX for CC-BW (697 kg) and proportion of overconditioned cows (3.6% vs. 2.9%). Feeding FLX diet during gestation resulted in cows with a greater (P ≤ 0.01) concentration of conjugated linolenic acid (0.12% vs. 0.05%) and n-3 (0.58% vs. 0.37%) fatty acids, and a tendency (P = 0.09) for conjugated linoleic acid concentration (1.05% vs. 0.88%) to be greater in subcutaneous adipose tissue (SCAT) when compared with cows fed the CAN diet. By the end of gestation, serum NEFA concentration of LF cows (592 µEq/L) was lower (P < 0.01) than that of HF cows, and FLX cows had greater (P < 0.01) serum NEFA concentration than CAN cows (636 vs. 961 µEq/L). Cows receiving the LF diet during gestation gave birth to lighter (P < 0.01) calves compared with those receiving the HF diets (40.2 vs. 42.9 kg), with no difference (P = 0.24) between calves born to CAN (42.4 kg) and FLX (43.3 kg) cows. In conclusion, these results suggest a partitioning of the ME in pregnant beef cows that is dependent on the type of dietary energy, resulting in heavier calves at birth for cows fed high-fat diets. Also, the type of fatty acid in the diet of gestating beef cows affected the fatty acid profile in SCAT and serum NEFA concentration.

Performance, nutrient utilization, and energy partitioning in broiler chickens offered high canola meal diets supplemented with multicomponent carbohydrase and mono-component protease

Two broiler chicken experiments were conducted to investigate the effects of canola meal (CM) replacing soybean meal (SBM) in diets supplemented with carbohydrase and protease on performance and partitioning of energy. First, a 2 × 2 × 2 factorial arrangement of treatments was employed to evaluate: protein meals (CM vs. SBM), carbohydrase (none or 300 mg/kg), protease (none or 200 mg/kg), and their interactions. Each treatment was fed to 6 replicated pens of 16 male broilers (Ross 308) from d 10 to 35. In the second experiment, 32 broiler chicks were used in a 2 × 2 factorial arrangement to investigate CM and carbohydrase effects on energy partitioning. Birds were transferred into 16 closed-circuit calorimeter chambers (4 chambers/diet; 2 birds/chamber) to measure heat production (HP), metabolizable and net energy (NE) by gaseous exchange, and total excreta collection from d 25 to 28. There were no 3-way interactions among experimental factors for any of the performance parameters measured. Birds given CM diets consumed less feed, had lower BW, and exhibited higher FCR compared to the control birds (P < 0.01). Both enzymes, alone or in combination, improved final BW and FCR (P < 0.05). There was an interaction between carbohydrase and protease for FCR over the grower period (P < 0.01), in which the combination of the enzymes resulted in further improvement of FCR. Energy, DM, and crude protein digestibility values were higher in control birds (P < 0.05). There was an interaction of protein meal and carbohydrase for HP, respiratory quotient (P < 0.05), and NE:ME ratio of the diets (P = 0.06). Inclusion of CM without carbohydrase increased HP and decreased NE and NE:ME ratio of the diets (P < 0.05). Carbohydrase decreased HP and increased retained energy (P = 0.06) and NE and NE:ME ratio (P < 0.05). In conclusion, high CM in the diet negatively affects growth performance through reduction in feed consumption, nutrient digestibility, and NE of the diet, which could partly be restored by enzyme supplementation.

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation

To achieve functional but also productive females, we hypothesised that it is possible to modulate acquisition and allocation of animals from different genetic types by varying the main energy source of the diet. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66), a maternal line characterised by hyper-prolificacy; LP (n=67), a maternal line characterised by functional hyper-longevity; R (n=79), a paternal line characterised by growth rate. Females were fed with two isoenergetic and isoprotein diets differing in energy source: animal fat (AF) enhancing milk yield; cereal starch (CS) promoting body reserves recovery. Feed intake, weight, perirenal fat thickness (PFT), milk yield and blood traits were controlled during five consecutive reproductive cycles (RCs). Females fed with CS presented higher PFT (+0.2 mm, P0.05), particularly for those fed with AF. Moreover, LP females fed with AF progressively increased PFT across the RC, whereas those fed with CS increased PFT during early lactation (+7.3%; P<0.05), but partially mobilised it during late lactation (-2.8%; P<0.05). Independently of the diet offered, LP females reached weaning with similar PFT. H females fed with either of the two diets followed a similar trajectory throughout the RC. For milk yield, the effect of energy source was almost constant during the whole experiment, except for the first RC of females from the maternal lines (H and LP). These females yielded +34.1% (P<0.05) when fed with CS during this period. Results from this work indicate that the resource acquisition capacity and allocation pattern of rabbit females is different for each genetic type. Moreover, it seems that by varying the main energy source of the diet it is possible to modulate acquisition and allocation of resources of the different genetic types. However, the response of each one depends on its priorities over time.

The Synergistic Responses of Different Photoprotective Pathways in Dwarf Bamboo (Fargesia rufa) to Drought and Subsequent Rewatering

Dwarf bamboo-dominated forests are often subjected to temporary periods of drought due to rising air temperature and decreasing rainfall. Nevertheless, the relationship among CO2 assimilation, photoprotective pathways and metabolism of reactive oxygen species (ROS) remains unexplored in bamboo species. Changes in leaf gas exchange, chlorophyll fluorescence, energy partitioning, antioxidative system and compounds related to ROS metabolism in Fargesia rufa plants subjected to drought and subsequent rewatering were analyzed. Drought resulted in a reversible inhibition of photochemistry, particularly net CO2 assimilation, and lipid peroxidation due to ROS accumulation. Meanwhile, photoprotective pathways, including the water-water cycle (especially for moderate drought), and adjustment in antenna pigments, thermal dissipation and antioxidative defense capacity at organelle levels (especially for severe drought), were up-regulated at the stress phase. Conversely, photorespiration was down-regulated after drought stress. As a result, rewatering restored most of the photochemical activity under drought, especially moderate drought. Moreover, thermal dissipation under severe drought was still operated for avoiding high ROS levels after rewatering. Therefore, the synergistic function of these photoprotective pathways except photorespiration can protect the photosynthetic apparatus from oxidative damage in response to varying intensities of drought stress when CO2 assimilation is restricted. This is helpful for the gradual recovery of photosynthetic capacity after rewatering. Thus, F. rufa plants can withstand drought and is capable of survival in such environment.

HIGHLIGHTS

1. The effects of drought and subsequent rewatering on Fargesia rufa were studied.2. Drought resulted in a reversible inhibition of photochemistry.3. Photoprotective pathways except photorespiration were up-regulated at the drought phase.4. Rewatering rapidly restored photochemical activity, especially under moderate drought.5. Fargesia rufa plant is capable of resisting and surviving drought environment.

Grazing effects on surface energy fluxes in a desert steppe on the Mongolian Plateau

Quantifying the surface energy fluxes of grazed and ungrazed steppes is essential to understand the roles of grasslands in local and global climate and in land use change. We used paired eddy-covariance towers to investigate the effects of grazing on energy balance (EB) components: net radiation (R_n ), latent heat (LE), sensible heat (H), and soil heat (G) fluxes on adjacent grazed and ungrazed areas in a desert steppe of the Mongolian Plateau for a two-year period (2010-2012). Near 95% of R_n was partitioned as LE and H, whereas the contributions of G and other components of the EB were 5% at an annual scale. H dominated the energy partitioning and shared ~50% of R_n . When comparing the grazed and the ungrazed desert steppe, there was remarkably lower R_n and a lower H, but higher G at the grazed site than at the ungrazed site. Both reduced available energy (R_n - G) and H indicated a "cooling effect" feedback onto the local climate through grazing. Grazing reduced the dry year LE but enhanced the wet year LE. Energy partitioning of LE/R_n was positively correlated with the canopy conductivity, leaf area index, and soil moisture. H/R_n was positively correlated with the vapor pressure deficit but negatively correlated with the soil moisture. Boosted regression tree results showed that LE/R_n was dominated by soil moisture in both years and at both sites, while grazing shifted the H/R_n domination from temperature to soil moisture in the wet year. Grazing not only caused an LE shift between the dry and the wet year, but also triggered a decrease in the H/R_n because of changes in vegetation and soil properties, indicating that the ungrazed area had a greater resistance while the grazed area had a greater sensitivity of EB components to the changing climate.

Dynamical Bifurcation in Gas-Phase XH- + CH3 Y SN 2 Reactions: The Role of Energy Flow and Redistribution in Avoiding the Minimum Energy Path

The gas-phase reactions of XH^- (X=O, S) + CH₃ Y (Y=F, Cl, Br) span nearly the whole range of S_N 2 pathways, and show an intrinsic reaction coordinate (IRC) (minimum energy path) with a deep well owing to the CH₃ XH⋅⋅⋅Y^- (or CH₃ S^- ⋅⋅⋅HF) hydrogen-bonded postreaction complex. MP2 quasiclassical-type direct dynamics starting at the [HX⋅⋅⋅CH₃ ⋅⋅⋅Y]^- transition-state (TS) structure reveal distinct mechanistic behaviors. Trajectories that yield the separated CH₃ XH+Y^- (or CH₃ S^- +HF) products directly are non-IRC, whereas those that sample the CH₃ XH⋅⋅⋅Y^- (or CH₃ S^- ⋅⋅⋅HF) complex are IRC. The IRCIRC/non-IRC ratios of 90:10, 40:60, 25:75, 2:98, 0:100, and 0:100 are obtained for (X, Y)=(S, F), (O, F), (S, Cl), (S, Br), (O, Cl), and (O, Br), respectively. The properties of the energy profiles after the TS cannot provide a rationalization of these results. Analysis of the energy flow in dynamics shows that the trajectories cross a dynamical bifurcation, and that the inability to follow the minimum energy path arises from long vibration periods of the X-C⋅⋅⋅Y bending mode. The partition of the available energy to the products into vibrational, rotational, and translational energies reveals that if the vibrational contribution is more than 80 %, non-IRC behavior dominates, unless the relative fraction of the rotational and translational components is similar, in which case a richer dynamical mechanism is shown, with an IRC/non-IRC ratio that correlates to this relative fraction.

[Characteristics of photosynthesis and light energy partitioning in Amorphophallus xiei grown along a light-intensity gradient.]

The objective of the present study was to examine the adaptation strategy of Amorphophallus xiei, a shade-demanding species, grown under different levels of light intensity. The responses of leaf to photosynthetic active radiation, CO₂ and simulated sunflecks were analyzed in A. xiei grown under 100% (high light), 32.6% (moderate light) and 5.98% (low light) of full sun. Meanwhile, chlorophyll a fluorescence parameter and light energy partitioning were also recorded and calculated in the above-mentioned responsive process. The results showed that in most cases, the maximum photosynthetic rate (P_max), dark respiration rate, apparent quantum yield and carboxylation efficiency in A. xiei significantly decreased with increasing the light level, however, the light compensation point, CO₂ compensation point significantly increased. The photosynthetic induction was quicker in individuals grown under moderate light (P<0.05), and the initial stomatal conductance (g_s-i) during dark adaptation increased significantly with increasing the light level. There was a ne-gative correlation between g_s-i and the time required to reach 30%, 50% and 90% of P_max during the process of photosynthetic induction. Moreover, the values of actual photochemical efficiency of PS2 (ΔF/F_m') in the light, phototochemical quenching of chlorophyll fluorescence (q_P) and photosynthetic electron transport rate (ETR) were higher and non-photochemical quenching (NPQ) recorded in photosynthetic induction was also higher in individuals grown under high light, nevertheless, the maximum photochemical efficiency of PS2 in the light (F_v'/F_m') was higher in individuals grown under low light. The proportion of light energy allocated to non-photochemical quenching (Ф_NPQ) was lower in individuals grown under high light, and, correspondingly, it was higher in ones grown under low light. The results obtained here suggested that, when exposed to high light stress, moderate- and low-light-grown A. xiei would activate the mechanism of energy dissipation to protect itself from injury. Correspondingly, high-light-grown individuals would employ the strategy of increasing heat dissipation and forming quenching complex to cope with high light stress, which, however, might be one of reasons for the sensitivity of A. xiei to high light environment.

Effects of ambient temperature, feather cover, and housing system on energy partitioning and performance in laying hens

Environmental factors, such as ambient temperature (T), feather cover (FC), and housing system (HS), probably affect energy requirements of laying hens. Using a 3 × 2 × 2 factorial arrangement, interaction effects of T (11, 16, and 21°C), FC (100 and 50%), and HS (cage and floor housing) on energy partitioning and performance of laying hens were investigated. Six batches of 70 H&N Brown Nick laying hens, divided over 2 respiration chambers, were exposed to the T levels in three 2-wk periods. Heat production (HP) was determined by indirect calorimetry. The ME intake was calculated by subtracting energy in manure/litter from that in feed and wood shavings. The NE was calculated by subtracting HP from ME. The ME intake increased by 1% for each degree reduction in T. In hens with intact plumage, HP was not affected by T, whereas at decreasing T, HP increased in hens with 50% FC (P < 0.01). At 21°C, HP was not affected by HS, whereas in the floor system, HP at 16 and 11°C was 5.8 and 3.0% higher, respectively, than in cages (P < 0.05). The NE for production was 25.7% higher in cages compared to the floor system (P < 0.05). In cages, 24.7% of NE for production was spent on body fat deposition, whereas in the floor system, 9.0% of NE for production was released from body fat reserves. The ME intake was predicted by the equation (R(2) = 0.74) ME intake (kJ/d) = 612 BW(0.75) - (8.54 × T) + (28.36 × ADG) + (10.43 × egg mass) - (0.972 × FC). Hen performances were not affected by treatments, indicating the adaptive capacity of young laying hens to a broad range of environmental conditions.

Milk production responses to a change in dietary starch concentration vary by production level in dairy cattle

The effects of dietary starch concentration on yield of milk and milk components were evaluated in a crossover design experiment. Holstein cows (n=32; 115±22 d in milk) with a wide range in milk yield (28 to 62kg/d) were assigned randomly within level of milk yield to a treatment sequence. Treatments were diets containing 30% dry ground corn (CG) or 30% soyhulls (SH) on a DM basis. Diets containing corn silage and alfalfa silage were formulated to contain 16% crude protein, 24% forage neutral detergent fiber, and either 27 or 44% neutral detergent fiber and 30 or 12% starch for CG and SH, respectively. Cows were fed a diet intermediate to the treatments during a preliminary 14-d period. Treatment periods were 28 d with measurements taken throughout the period for energy calculations and the final 5 d used for data and sample collection for production variables. Compared with SH, CG increased dry matter intake, and yields of milk, milk protein, milk fat, and energy-corrected milk, as well as milk protein concentration. Treatment did not affect milk fat concentration. Yield of de novo synthesized and preformed milk fatty acids increased with CG. Treatment interacted with level of preliminary milk production for several response variables (yields of milk, milk protein, milk fat, energy-corrected milk, and 3.5% fat-corrected milk). Compared with SH, the CG treatment increased energy-corrected milk in higher-producing cows with a lesser response to CG as milk yield decreased. The CG treatment increased milk:feed compared with the SH treatment, but not body weight or body condition score. In conclusion, higher-producing cows benefited from the high-starch diet, and lower-producing cows were able to maintain production when most of the starch was replaced with nonforage fiber.

Detection of Photosynthetic Performance of Stipa bungeana Seedlings under Climatic Change using Chlorophyll Fluorescence Imaging

In this study, the impact of future climate change on photosynthetic efficiency as well as energy partitioning in the Stipa bungeana was investigated by using chlorophyll fluorescence imaging (CFI) technique. Two thermal regimes (room temperature, T0: 23.0/17.0°C; High temperature, T6: 29.0/23.0°C) and three water conditions (Control, W0; Water deficit, W-30; excess precipitation, W+30) were set up in artificial control chambers. The results showed that excess precipitation had no significant effect on chlorophyll fluorescence parameters, while water deficit decreased the maximal quantum yield of photosystem II (PSII) photochemistry for the dark-adapted state (F v/F m) by 16.7%, with no large change in maximal quantum yield of PSII photochemistry for the light-adapted state (F V'/F M') and coefficient of the photochemical quenching (q P ) at T0 condition. Under T6 condition, high temperature offset the negative effect of water deficit on F v/F m and enhanced the positive effect of excess precipitation on F v/F m, F v'/F m', and q P , the values of which all increased. This indicates that the temperature higher by 6°C will be beneficial to the photosynthetic performance of S. bungeana. Spatial changes of photosynthetic performance were monitored in three areas of interest (AOIs) located on the bottom, middle and upper position of leaf. Chlorophyll fluorescence images (F v/F m, actual quantum yield of PSII photochemistry for the light-adapted state (ΦPSII), quantum yield of non-regulated energy dissipation for the light-adapted state (ΦNO) at T0 condition, and ΦPSII at T6 condition) showed a large spatial variation, with greater value of ΦNO and lower values of F v/F m and ΦPSII in the upper position of leaves. Moreover, there was a closer relationship between ΦPSII and ΦNO, suggesting that the energy dissipation by non-regulated quenching mechanisms played a dominant role in the yield of PSII photochemistry. It was also found that, among all measured fluorescence parameters, the F v/F m ratio was most sensitive to precipitation change at T0, while ΦPSII was the most sensitive indicator at T6.

Regulatory roles for L-arginine in reducing white adipose tissue

As the nitrogenous precursor of nitric oxide, L-arginine regulates multiple metabolic pathways involved in the metabolism of fatty acids, glucose, amino acids, and proteins through cell signaling and gene expression. Specifically, arginine stimulates lipolysis and the expression of key genes responsible for activation of fatty acid oxidation to CO2 and water. The underlying mechanisms involve increases in the expression of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha), mitochondrial biogenesis, and the growth of brown adipose tissue growth. Furthermore, arginine regulates adipocyte-muscle crosstalk and energy partitioning via the secretion of cytokines and hormones. In addition, arginine enhances AMP-activated protein kinase (AMPK) expression and activity, thereby modulating lipid metabolism and energy balance toward the loss of triacylglycerols. Growing evidence shows that dietary supplementation with arginine effectively reduces white adipose tissue in Zucker diabetic fatty rats, diet-induced obese rats, growing-finishing pigs, and obese patients with type II diabetes. Thus, arginine can be used to prevent and treat adiposity and the associated metabolic syndrome.

BDNF contributes to the genetic variance of milk fat yield in german holstein cattle

The gene encoding the brain-derived neurotrophic factor (BDNF) has been repeatedly associated with human obesity. As such, it could also contribute to the regulation of energy partitioning and the amount of secreted milk fat during lactation, which plays an important role in milk production in dairy cattle. Therefore, we performed an association study using estimated breeding values (EBVs) of bulls and yield deviations of German Holstein dairy cattle to test the effect of BDNF on milk fat yield (FY). A highly significant effect (corrected p-value = 3.362 × 10(-4)) was identified for an SNP 168 kb up-stream of the BDNF transcription start. The association tests provided evidence for an additive allele effect of 5.13 kg of fat per lactation on the EBV for milk FY in bulls and 6.80 kg of fat of the own production performance in cows explaining 1.72 and 0.60% of the phenotypic variance in the analyzed populations, respectively. The analyses of bulls and cows consistently showed three haplotype groups that differed significantly from each other, suggesting at least two different mutations in the BDNF region affecting the milk FY. The FY increasing alleles also had low but significant positive effects on protein and total milk yield which suggests a general role of the BDNF region in energy partitioning, rather than a specific regulation of fat synthesis. The results obtained in dairy cattle suggest similar effects of BDNF on milk composition in other species, including man.

Physiological Response of Resistant and Susceptible Vitis vinifiera Cultivars to Meloidogyne incognita

The effect of Meloidogyne incognita on growth, general physiological response, and the concentration of reducing and nonreducing sugars at the nematode feeding sites of French Colombard (susceptible) and Thompson Seedless (moderately resistant) Vitis vinifiera cultivars was studied up to 2,100 degree-days (DD-base 10 C). Nematode stress dosage, measured as the product of cumulative number of juveniles and females and their total energy (calories) demand, accounted for up to 15 and 10% of the energy assimilated by French Colombard and Thompson Seedless plants, respectively. Total leaf area, total carbon dioxide fixed, transpiration rate, stomatal conductance, and internal leaf CO concentration were not affected, but energy assimilated into plant tissue and respiration were decreased by nematode infection in both cultivars. Energy consumed by nematodes accounted for most of the difference in total energy assimilated between infected and uninfected plants on French Colombard but not on Thompson Seedless, suggesting that the resistant cultivar may be using more energy to curtail the nematode's activity. Nematodes did not affect the concentration of reducing sugars, but the concentration of nonreducing sugars increased in French Colombard and decreased in Thompson Seedless. This indicates that there was more translocation of photosynthate to the feeding sites of the susceptible than to those of the resistant cultivar, and may explain why M. incognita causes more damage to French Colombard than to Thompson Seedless.

Impact of Meloidogyne incognita on Physiological Efficiency of Vitis vinifera

Four-week-old French Colombard plants rooted from green cuttings were inoculated with 0, 1,000, 2,000, 4,000, or 8,000 Meloidogyne incognita second-stage juveniles and maintained at 25 C night and 30 C day. Leaf area and dry weight and the rates of photosynthesis, stomatal conductance, and internal leaf CO concentration were measured at intervals up to 59 days after inoculation. Nematode stress dosage, measured as the product of cumulative number of juveniles and females and their total energy (calories) demand, was up to 3.4 kcal and accounted for up to 15% of the energy assimilated by the plants. There was a decline in the rate of leaf area expansion and leaf, stem, shoot, root (excluding nematode weight), and total plant dry weight with increasing nematode stress. Root weight including nematodes was not affected. Total respiration, plant photosynthesis, energy assimilated into plant tissue and respiration, and gross production efficiency decreased significantly with nematode stress. Photosynthetic rate, transpiration rate, stomatal conductance, and internal CO concentration were not affected. This study demonstrates that the energy demand for growth and reproduction of M. incognita accounts for a significant portion of the total energy entering the plant system. As a result, less energy is partitioned into leaf area expansion which, in turn, affects the energy entering the system and results in decreased productivity of nematode-infected grape vines.