Responses to nutrients in farm animals: implications for production and quality

It is well known that any quantitative (energy and protein levels) and qualitative (nature of the diet, nutrient dynamic) changes in the feeding of animals affect metabolism. Energy expenditure and feed efficiency at the whole-body level, nutrient partitioning between and within tissues and organs and, ultimately, tissue and organ characteristics are the major regulated traits with consequences on the quality of the meat and milk produced. Recent progress in biology has brought to light important biological mechanisms which explain these observations: for instance, regulation by the nutrients of gene expression or of key metabolic enzyme activity, interaction and sometimes cross-regulation or competition between nutrients to provide free energy (ATP) to living cells, indirect action of nutrients through a complex hormonal action, and, particularly in herbivores, interactions between trans-fatty acids produced in the rumen and tissue metabolism. One of the main targets of this nutritional regulation is a modification of tissue insulin sensitivity and hence of insulin action. In addition, the nutritional control of mitochondrial activity (and hence of nutrient catabolism) is another major mechanism by which nutrients may affect body composition and tissue characteristics. These regulations are of great importance in the most metabolically active tissues (the digestive tract and the liver) and may have undesirable (i.e. diabetes and obesity in humans) or desirable consequences (such as the production of fatty liver by ducks and geese, and the production of fatty and hence tasty meat or milk with an adapted fatty acid profile).     

Anthropogenic nitrogen sources and relationships to riverine nitrogen export in the northeastern U.S.A.

Human activities have greatly altered the nitrogen (N) cycle, accelerating the rate of N fixation in landscapes and delivery of N to water bodies. To examine relationships between anthropogenic N inputs and riverine N export, we constructed budgets describing N inputs and losses for 16 catchments, which encompass a range of climatic variability and are major drainages to the coast of the North Atlantic Ocean along a latitudinal profile from Maine to Virginia. Using data from the early 1990's, we quantified inputs of N to each catchment from atmospheric deposition, application of nitrogenous fertilizers, biological nitrogen fixation, and import of N in agricultural products (food and feed). We compared these inputs with N losses from the system in riverine export.The importance of the relative sources varies widely by catchment and is related to land use. Net atmospheric deposition was the largest N source (>60%) to the forested basins of northern New England (e.g. Penobscot and Kennebec); net import of N in food was the largest source of N to the more populated regions of southern New England (e.g. Charles & Blackstone); and agricultural inputs were the dominant N sources in the Mid-Atlantic region (e.g. Schuylkill & Potomac). Over the combined area of the catchments, net atmospheric deposition was the largest single source input (31%), followed by net imports of N in food and feed (25%), fixation in agricultural lands (24%), fertilizer use (15%), and fixation in forests (5%). The combined effect of fertilizer use, fixation in crop lands, and animal feed imports makes agriculture the largest overall source of N. Riverine export of N is well correlated with N inputs, but it accounts for only a fraction (25%) of the total N inputs. This work provides an understanding of the sources of N in landscapes, and highlights how human activities impact N cycling in the northeast region.     

A simple method to control the bacterial production of cellulosic films in order to obtain dried pellicles presenting a desired average thickness

During the bacterial production of cellulosic films on non-agitated liquid media, the mass of the system does not change. An equation is therefore proposed to evaluate the volume of inoculated medium to be placed in a given tray so that, when no more free aqueous medium may be detected under the wet pellicle produced, a dried film of a desired average thickness is produced.     

Process development with nitrogenase-producing Escherichia coli C-M74 (pUS1) CellS

A process for the continuous fermentation of the genetically modified, nitrogenase-producing Escherichia coli C-M74 (pUS1)-strain has been developed. This strain, which is able to fix molecular nitrogen, has the nifgenes of the bacterium Klebsiella pneumoniae. Cell growth and nitrogenase activity of the enzyme have been optimized both in batch and continuous fermentations. For the fermentations, trial runs were performed by cultivating the E. coli cells in 50-ml culture bottles. The medium composition was varied in order to provide high biomass production and nitrogenase activity. For an effective fermentation control, an on-line analysis was built up for the substrates ammonium and glucose. Other medium components such as ampicillin, citric acid, acetic acid, nitrogenase activity, and protein were measured by using different off-line methods. Modern optical methods like in-line microfluorometry for monitoring the culture fluorescence and laser flow cytometry for the estimation of DNA and protein content were also employed. Plasmid stability was also determined.     

牛α1-AT基因5’侧翼区新SNPS的鉴定及其与产奶性状的相关性

以中国荷斯坦奶牛(Chinese Holstein dairy cattle)为对象,以α1 抗胰蛋白酶基因(α1-AT)为候选基因,扩增5′侧翼区668 bp和999 bp的片段并进行测序.首次发现,在+3 142 bp处P1和+4 408 bp处P2分别发生C-T、T-C突变.随后采用PCR-RFLP方法对随机采自6个牛场,共计294头牛进行了检测,遗传变异和产奶性状分析结果显示：2个位点的等位基因在群体中都有分布,且处于中度多态.P1位点A和B等位基因的频率分别为50.34%和49.66%; AA、AB和BB基因型频率分别为23.81%、53.06%和23.13%;P2位点E和F等位基因的频率分别为30.61%和69.39%, EE、EF和FF基因型频率分别为11.90%、37.41%和50.68%. χ2适合性检验表明,该群体在P1位点的突变达到Hardy-Weinberg平衡状态（P>0.05）,在P2位点未达到平衡.基因与产奶性状关联分析表明,AB基因型个体产奶量与脂蛋比显著高于AA基因型个体(P＜0.05);FF基因型个体乳蛋白率显著高于EF基因型个体(P＜0.05);9种单倍型组合与乳脂率、乳蛋白率、体细胞数、产奶量及脂蛋比均存在不同程度相关性.     

The importance of ‘tooglies’ to the ethnography of F.E. Williams,government anthropologist

The theoretical orientation, encapsulated in the semi‐serious concept of ‘tooglies'of F.E. Williams, government anthropologist for the Territory of Papua in the inter‐war period, is considered. His ideas about culture change are contrasted with those of Bronislaw Malinowski, who acted as his mentor at one time. His treatment of the social organisational anomaly of Sogeri Koiari ‘sex affiliation’, often cited as a case of parallel bilineal descent, is compared with Margaret Mead's analysis of the ‘Mundugumor ropes’, which is classed as the opposite, cross‐sex bilineal descent. It is shown that Williams was able to get a clearer insight into this anomalous data than Mead and Fortune, and, on the whole, worked with an understanding of culture and Papuan social organisation that presages the relational approach of today.     

EFFECTS OF VARIATIONS IN LIGHT INTENSITY ON THE EFFICIENCY OF GROWTH OF SKELETONEMA COSTATUM (BACILLARIOPHYCEAE) IN A CYCLOSTAT1

The relative importance of respiration and organic carbon release to the efficiency of carbon specific growth of Skeletonema costatum (Grev.) Clave was evaluated over a light range from 1500–15 μE · m^?2· s^?1. Net growth efficiency ranged from 0.45–0.69 with a maximum at 130 μE · m^?2· s^?1. Respiration was 93% or more of the variations in growth efficiency. Organic carbon release ranged from 0–7% of gross production and increased with light intensity. Carbon specific particulate production was a hyperbolic function of incident light intensity and was related exponentially to particulate carbon production per unit chlorophyll a. Full sunlight conditions, 1500 μE · m^?2· s^?1, did not induce photoinhibition of gross production. Variations in the efficiency of growth of S. costatum were minimized over a wide range of light intensities mainly because of variations in cellular pigments which permitted the efficient utilization of available light energy, and a reduction in the losses of carbon which increases the growth rate, possibly as a consequence of the recycling of respired carbon within the cell.     

Effect of iron concentration on hydrogen fermentation

The effect of the iron concentration in the external environment on hydrogen production was studied using sucrose solution and the mixed microorganisms from a soybean-meal silo. The iron concentration ranged from 0 to 4000 mgFeCl₂ l⁻¹. The temperature was maintained at 37°C. The maximum specific hydrogen production rate was found to be 24.0 mlg⁻¹ VSSh⁻¹ at 4000 mgFeCl₂ l⁻¹. The specific production rate of butyrate increased with increasing iron concentration from 0 to 20 mgFeCl₂ l⁻¹, and decreased with increasing iron concentration from 20 to 4000 mgFeCl₂ l⁻¹. The maximum specific production rates of ethanol (682 mgg⁻¹ VSSh⁻¹) and butanol (47.0 mgg⁻¹ VSSh⁻¹) were obtained at iron concentrations of 5 and 3 mgFeCl₂ l⁻¹, respectively. The maximum hydrogen production yield of 131.9 mlg⁻¹ sucrose was obtained at the iron concentration of 800 mgFeCl₂ l⁻¹. The maximum yields of acetate (389.3 mgg⁻¹ sucrose), propionate (37.8 mgg⁻¹ sucrose), and butyrate (196.5 mg g⁻¹ sucros) were obtained at iron concentrations of 3, 200 and 200 mgFeCl₂ l⁻¹, respectively. The sucrose degradation efficiencies were close to 1.0 when iron concentrations were between 200 and 800 mgFeCl₂ l⁻¹. The maximum biomass production yield was 0.283 gVSSg⁻¹ sucrose at an iron concentration of 3000 mgFeCl₂ l⁻¹.     

Measurements of gross and net ecosystem productivity and water vapour exchange of a Pinus ponderosa ecosystem,and an evaluation of two generalized models

Net ecosystem productivity (NEP), net primary productivity (NPP), and water vapour exchange of a mature Pinus ponderosa forest (44°30′ N, 121°37′ W) growing in a region subject to summer drought were investigated along with canopy assimilation and respiratory fluxes. This paper describes seasonal and annual variation in these factors, and the evaluation of two generalized models of carbon and water balance (PnET‐II and 3‐PG) with a combination of traditional measurements of NPP, respiration and water stress, and eddy covariance measurements of above‐and below‐canopy CO₂ and water vapour exchange. The objective was to evaluate the models using two years of traditional and eddy covariance measurements, and to use the models to help interpret the relative importance of processes controlling carbon and water vapour exchange in a water‐limited pine ecosystem throughout the year. PnET‐II is a monthly time‐step model that is driven by nitrogen availability through foliar N concentration, and 3‐PG is a monthly time‐step quantum‐efficiency model constrained by extreme temperatures, drought, and vapour pressure deficits. Both models require few parameters and have the potential to be applied at the watershed to regional scale. There was 2/3 less rainfall in 1997 than in 1996, providing a challenge to modelling the water balance, and consequently the carbon balance, when driving the models with the two years of climate data, sequentially. Soil fertility was not a key factor in modelling processes at this site because other environmental factors limited photosynthesis and restricted projected leaf area index to ～1.6. Seasonally, GEP and LE were overestimated in early summer and underestimated through the rest of the year. The model predictions of annual GEP, NEP and water vapour exchange were within 1–39% of flux measurements, with greater disparity in 1997 because soil water never fully recharged. The results suggest that generalized models can provide insights to constraints on productivity on an annual basis, using a minimum of site data.