Estimating unit costs of nutrients from market prices of feedstuffs

The determinations of nutrient costs and breakeven prices of feedstuffs are important activities in the field of nutritional economics. Current methods are either extensions of the Petersen method, which dates back to 1932, or mathematical programming methods generally set as linear programming problems. Both sets of methods have severe limitations that make them unsuitable or biased for deriving unit costs of nutrients and aggregate breakeven costs of feedstuffs in a given market. We propose a least-squares method that, under verifiable conditions, yields maximum likelihood estimates of unit costs of nutrients and breakeven prices of feedstuffs. Assumptions to the maximum likelihood estimates are verified with studentized residuals, leverage values, and variance inflation factors. The method has been programmed into a Windows application and can be used by those with little formal training in statistics.     

Effects of 2-hydroxy-4-(methylthio) butanoic acid (HMB) on microbial growth in continuous culture

2-Hydroxy-4-(methylthio) butanoic acid (HMB) positively affects milk composition and yield, potentially through ruminal actions. Four continuous culture fermenters were used to determine the optimal concentration of HMB for digestibility of organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose and synthesis of microbial N. A highly degradable mix of hay and grain was used as a basal diet to simulate a typical lactation diet. Three concentrations of HMB (0, 0.055, and 0.110%) and one concentration of dl-Met (0.097%) were infused into the fermenters according to a 4 x 4 Latin square design. Digesta samples were collected during the last 3 d of each of the four 10-d experimental periods. Digestibility of OM, hemicellulose, and NDF was largely insensitive to treatment. Digestibility of ADF showed a quadratic effect to supplementation of HMB, with 0.055% having lower digestibility than 0 or 0.110%. Total production of VFA was not influenced by HMB supplementation, but differences in concentration and production of individual VFA were seen. Isobutyrate increased linearly with increasing HMB supplementation. Propionate concentration decreased linearly with increased HMB supplementation, but propionate production showed a quadratic trend (P = 0.13). A higher concentration of acetate was detected for dl-Met compared with the highest HMB concentration. There were trends (P < 0.15) for dl-Met to decrease the production of isobutyrate and to lower the concentration of butyrate when compared with HMB. Microbial efficiency was not different among treatments. The proportion of bacterial N produced from NH3-N decreased linearly with increasing HMB, and bacteria receiving dl-Met synthesized more N from NH3-N than those receiving HMB. These data suggest that supplementation of HMB may have a sparing effect on branched chain volatile fatty acids because the fatty acids are not needed to provide carbon for synthesis of valine, isoleucine and leucine with ammonia. Comparisons of bacterial community structure in the fermenter effluent samples using PCR amplicons containing the ribosomal intergenic spacer region and its flanking partial 16S ribosomal RNA gene showed no distinct banding patterns, though treatments tended to group together. Both Met and HMB affect the rumen microbial population, but Met supplied as dl-Met does not act identically to that supplied as HMB.     

Forecasting herd structure and milk production for production risk management

Substantial increases in milk price volatility have resulted from changes in federal dairy policies. For a dairy farm, however, monthly gross milk receipts are a function of unit price and quantity produced. Both can vary substantially over time. Therefore, to be effective, risk management strategies must address milk and input price volatility (price risk management) and fluctuations in milk production per cow and cow numbers (production risk management). Herd milk production through time can be modeled as a discrete stochastic process using finite Markov chains. Cows at time t = 0 are assigned to homogeneous production cells in four-dimensional arrays with coordinates determined by parity (1, 2, 3), week in milk (1, ..., 104), pregnancy status (0, 1), and week pregnant (1, ..., 40). The processes of aging, pregnancy, involuntary cull, voluntary cull, abortion, dry-off, and freshening from week i-1 to week i are accounted for, using nonstationary transition probabilities. Bayesian estimates of transition probabilities are derived from historical herd data, assuming that individual outcomes are from Bernoulli distributions. The values of parameters theta(i) for the Bernoulli distributions are unknown but have prior distributions that follow beta distributions with parameters alpha(i) and beta(i) estimated from historical data. Herd observations are then used to generate posterior distributions of theta(i), also from beta distributions. Projecting from one week to the next is accomplished by moving virtual animals from one production cell to the next based on the transition probability assigned to that path. Summing production estimates and variances of all independent cells provides for an expected herd production with an associated variance. As expected, the forecast variance increases with time, reflecting increased uncertainty of distant projections. Model validation presents an interesting problem because future observations used for validation are under human control and are not independent of the forecast.     

A Framework for the Development of an Environmental Management System: A Case Study in a Thermal Power Plant

A framework for the development of an environmental management system that satisfies the requirements of the ISO 14001 standards is presented. The framework is developed for NB Power, a company producing electricity for the province of New Brunswick in Canada. A case study is carried out in a thermal power plant called Coleson Cove. An initial review of the existing environmental management programs is presented. The environmental policy is evaluated, and the environmental aspects and impacts of the plant's activities are identified and prioritized according to prespecified criteria of severity, frequency, degree of control, and existence of regulation. Environmental objectives and targets are set and recommendations are presented.     

Bi-directional induction of matrix metalloproteinase-9 and tissue inhibitor of matrix metalloproteinase-1 during T lymphoma/endothelial cell contact: implication of ICAM-1

The mechanisms that lead to the expression of matrix metalloproteinases (MMP) and tissue inhibitors of MMP (TIMPs) during the invasive process of normal and transformed T cells remain largely unknown. Since vascular cells form a dynamic tissue capable of responding to local stimuli and activating cells through the expression of cytokine receptors and specific cell adhesion molecules, we hypothesized that the firm adhesion of T lymphoma cells to endothelial cells is a critical event in the local production of MMP and TIMP. In the present work, we show that adhesion of lymphoma cells to endothelial cells induced a transient and reciprocal de novo expression of MMP-9 mRNA and enzymatic activity by both cell types. Up-regulation of MMP-9 in T lymphoma cells was concomitant to that of TIMP-1, and required direct contact with endothelial cells. Induction of MMP-9, but not of TIMP-1, was blocked by anti-LFA-1 and anti-intercellular adhesion molecule-1 Abs, indicating that induction of MMP-9 and TIMP-1 in lymphoma cells required direct, yet distinct, intercellular contact. In contrast, the induction of MMP-9 in endothelial cells by T lymphoma cells did not necessitate direct contact and could be achieved by exposure to IL-1 and TNF, or to the supernatant of T lymphoma cell culture. Together, these results demonstrate that firm adhesion of T lymphoma cells to endothelial cells participates in the production of MMP-9 in both cell types through bi-directional signaling pathways, and identify intercellular adhesion molecule-1/LFA-1 as a key interaction in the up-regulation of MMP-9 in T lymphoma cells.     

The terminal O-acetyltransferase involved in vindoline biosynthesis defines a new class of proteins responsible for coenzyme A-dependent acyl transfer

The gene encoding acetyl CoA:deacetylvindoline 4-O-acetyltransferase (DAT) (EC 2.3.1.107) which catalyzes the last step in vindoline biosynthesis was isolated and characterized. The genomic clone encoded a 50 kDa polypeptide containing the sequences of nine tryptic fragments derived from the purified DAT heterodimer. However, cleavage of DAT protein to yield a heterodimer appears to be an artifact of the protein purification procedure, since the size of the protein (50 kDa) cross-reacting with anti-DAT antibody in seedlings and in leaves of various ages also corresponds to the size of the active recombinant enzyme. Studies with the intact plant and with developing seedlings showed that induction of DAT mRNA, protein accumulation and enzyme activity occurred preferentially in vindoline producing tissues such as leaves and cotyledons of light-treated etiolated seedlings. The ORF of DAT showed significant sequence identity to 19 other plant genes, whose biochemical functions were mostly unknown. The Mr of approximately 50 kDa, a HXXXDG triad, and a DFGWGKP consensus sequence are highly conserved among the 20 plant genes and these criteria may be useful to identify this type of acyltransferase. The involvement of some of these genes in epicuticular wax biosynthesis, fruit-ripening and in benzoyltransfer reactions indicates that the plant kingdom contains a superfamily of multifunctional acyltransferases which operate by a reaction mechanism related to the ancient chloramphenicol O-acetyltransferase and dihydrolipoyl acetyltransferase class of enzymes.     

Determination of rumen degradability and ruminal effects of three sources of methionine in lactating cows

Objectives were to quantify the ruminal effects and flows to the omasum of Met provided as 2-hydroxy-4-(methylthio)-butanoic acid (HMB), the isopropyl ester of HMB (HMBi), and DL-Met. Eight ruminally cannulated cows were used in a replicated 4 x 4 Latin square design. Treatments were 1) no Met (control), 2) HMB at 0.10% of DM, 3) HMBi at 0.13% of DM, and 4) DL-Met at 0.088% of DM. Diets were identical except for type of Met supplement and were based on corn silage and alfalfa hay at 30 and 13% of dietary DM, respectively. Samples of omasal fluid were used to determine the proportion of Met supplements passing out of the reticulorumen. Dry matter intake (20.1 kg/d) was restricted during the week of sampling to a maximum of 95% of ad libitum DMI determined during the first 2 wk of the period. Milk yields (37.7 +/- 0.8 kg/d) and fat concentration (3.42 +/- 0.15%) were not significantly different for control, HMB, HMBi, and DL-Met. Milk protein concentration (2.91, 2.95, 3.02, 2.96 +/- 0.07%, respectively) was significantly increased by the HMBi treatment. Rumen volatile fatty acids profile and NH3 concentrations were similar across treatments. Apparent ruminal digestibility of organic matter and neutral detergent fiber were higher for the three diets supplemented with Met sources than for the control diet. In situ rate of digestibility of CP from alfalfa hay, TMR, and corn silage was affected by Met sources. Passage rates of small particles (0.071/h) and fluid (0.167/h) were not affected by treatments. Protozoal counts in the rumen and omasum were not significantly affected by Met sources. Proportion of omasal N from bacterial N was not different (0.54 +/- 0.03), and bacterial N flow (305 +/- 24.4 g/d) was similar across treatments. The proportion of HMB that passed into the omasum was 5.3 +/- 1.5% of the amount consumed. Only a small amount (2.3%) of HMBi was found as HMB in the omasum. These results indicate that little HMB escapes ruminal degradation through passage to the omasum and that the site of HMBi absorption must be preomasal.     

Who profits from the Canadian nanotechnology reward system? Implications for gender-responsible innovation

Scientometrics - Gender equality is one of the primary dimensions of responsible research and innovation. Based on bibliometric and survey data of nanotechnology researchers in Canada, this paper...     

Effect of silica nucleants on the rates of crystallization of poly(ethylene terephthalate)

Studies of the crystallization of poly(ethylene terephthalate) (PET) by d.s.c., both isothermally and non-isothermally, show that the addition of silica causes marked increases in rate at loadings < 1 part filler in 100 parts polymer. At higher loadings the overall rate of crystallization decreases until it becomes less than that of un-nucleated PET. Modified silica, with an alkoxy-coated surface, causes similar but less pronounced changes in rate. The retardation in rate inspite of an increase in the number of spherulites is attributed to an increase in the viscosity of the polymer melt due to strong adsorption onto the silica particles.