Prediction of ruminal pH from pasture-based diets

This study identified suitable predictors of ruminal pH and identified relationships between ruminal pH and animal measures for diets based on fresh pasture. Animal and dietary variables (121 treatment means from six countries) were collated from 23 studies of lactating dairy cows fed pasture. Mean daily ruminal pH ranged from 5.6 to 6.7 across studies. Within studies, a low ruminal pH was associated with higher (P < 0.05; r2 > 0.40) microbial N flow from the rumen, total and individual volatile fatty acid concentrations, milk and milk component yields, and dry matter intake, and with lower (P < 0.05; r2 > 0.30) concentrations of milk fat, fat:protein, and acetate:propionate. Large variation between studies meant that these ruminal and production variables could not be used to make reliable predictions of ruminal pH in future pasture-based studies or feeding scenarios. Ruminal pH was positively related (P < 0.05; r2 < 0.15) to forage neutral detergent fiber (NDF) and NDF content within study, and negatively related (P = 0.001; r2 = 0.14) to nonstructural carbohydrate across studies. No single dietary variable, or group of variables, could be used to make a reliable prediction of ruminal pH. Estimates of effective fiber for diets containing only pasture were made using the Cornell Net Carbohydrate and Protein System ruminal pH equation. Mean effectiveness of fiber in pasture was 43% of NDF, and ranged from 17 to 78% across studies. High flows of microbial nitrogen, milk, milk fat yield, and dry matter intake suggested that the performance of cows fed high quality pasture was not limited when mean ruminal pH decreased to 5.8.     

Short communication: relationship between body growth and mammary development in dairy heifers

Our objective was to determine if prepubertal rate of body weight (BW) gain, independent of diet, was related to mammary development of dairy heifers. Data from two studies recently conducted at Michigan State University were used to identify factors, within a dietary treatment group, that would account for variation in first lactation milk production or amount of mammary parenchymal DNA at the time of puberty. Factors analyzed for variation in milk production during first lactation were: postpartum BW, prepubertal BW gain, gestational BW gain, postpartum BW gain, body condition score (BCS) at breeding, and BCS at calving. Factors analyzed for variation in mammary parenchymal DNA at puberty were: BW at slaughter, age at puberty, prepubertal BW gain and body protein and body fat content at slaughter. For both analyses, prepubertal BW gain did not account for any of the variation in mammary development. The only significant covariate for the milk production model (r2 = 0.44) was BCS at breeding. Similarly, the only significant covariate in the parenchymal DNA model (r2 = 0.22) was body fat content at slaughter. These results suggest that, within a dietary treatment, heifers that grow faster do not have impaired mammary development, and increased body fatness may be a better predictor of impaired mammary development than BW gain.     

Inhibition of bacterial foodborne pathogens by the lactoperoxidase system in combination with monolaurin

The lactoperoxidase system (LPS) and monolaurin (ML) are potential natural antimicrobial agents for use in foods. The LPS is considered to have greatest activity against Gram-negative bacteria while ML is usually considered to have greatest activity against Gram-positive bacteria. An LPS-ML combination system (utilizing lactoperoxidase (LPX) in the range 5-200 mg kg(-1) and ML in the range 50-1,000 ppm) inhibited growth of Escherichia coli O157:H7 and Staphylococcus aureus. Growth of S. aureus was inhibited more strongly in broth than in milk, in milk than in ground beef A similar pattern was observed for E. coli O157:H7, though enhanced inhibition by LPS-ML systems over that obtained in comparable LPS only systems was not observed in ground beef The inhibitory action of the LPS in combination with other lipids was also examined, with progressively weaker inhibition observed in combinations including palmitoleic acid, monopalmitolein, lauric acid, caprylic acid, and sodium lauryl sulphate.     

Empirical model building based on Weibull distribution to describe the joint effect of pH and temperature on the thermal resistance of Bacillus cereus in vegetable substrate

A total of 296 lactic acid bacteria (LAB) isolated from spoiled, vacuum-packaged 'gravad' rainbow trout stored at 3 and 8 degrees C were characterised and identified using a molecular approach. The isolates were initially grouped according to their HindIII restriction endonuclease profiles and further identified to species level using an rRNA gene restriction pattern (ribotype) identification database. Lactobacillus sakei, L. curvatus and Carnobacterium piscicola were the three main species detected. Only one isolate was identified as C. divergens. Most of the carnobacteria were found in the samples stored at 3 degrees C. The relative proportion of L. sakei was higher in the samples stored at 8 degrees C.     

Essential and non essential amino acid content of infant cereals in different stages of industrial processing and its relationship with chemical scores of protein quality

The effect of technological process on essential and non essential amino acids contents in infant cereals, the protein and essential amino acids infant dietary requirements cover by infant cereals, and its quality using some chemical scores has been studied. Mix of raw flours, mix of roasted flours, mix of enzymatically, hydrolysed and drum dried flours and commercial infant cereals of four different types of infant cereals: "Multicereal" and "Wheat" (both with gluten), "Growth" and "Rice and carrot" (both gluten free) were evaluated. The technological process only show a significant effect on lysine, arginine (P < 0.05) and valine (P < 0.01) contents in "Rice and carrot" infant cereal. Protein of any studied infant cereals covers 17.4% of the daily infant requirements in, while for essential amino acids will cover about 25 to 200% until the third year of life. As we expected, the limitant amino acid was lysine in all flours. Chemical scores only were affected by technological treatment in "Rice and carrot" infant cereal, showing the gluten-free infant cereals higher values (36.7-69.5%) than gluten infant cereals (18.1%-30.7%) at the end of the processing. It should be standing out "Growth" infant cereal, because of it has a higher lysine content than other infant cereals due to the main ingredients rice and corn.     

Behavioral responses of the parsnip webworm to host plant volatiles

Sixth instars of the parsnip webworm, Depressaria pastinacella, orient by olfaction to bud, male flowers, and female flowers of their primary host plant, Pastinaca sativa. Because octyl acetate and octyl butyrate are characteristic of tissues consumed by the sixth instar, we investigated the influence of these esters on webworm feeding behavior and chemo-orientation. Although octyl acetate and octyl butyrate are feeding deterrents, and octyl butyrate is an olfactory repellent, octyl acetate serves as an olfactory attractant. In olfactometers, webworms do not show a preference when given a choice between octyl acetate and host plant tissues. These findings suggest that octyl acetate is a sufficient cue for olfactory orientation. Such behavior may explain differences in the relative abundance of these esters observed among populations of wild parsnip under differential selection pressure from these insects.     

Biomolecular screening with encoded porous-silicon photonic crystals

Strategies to encode or label small particles or beads for use in high-throughput screening and bioassay applications focus on either spatially differentiated, on-chip arrays or random distributions of encoded beads. Attempts to encode large numbers of polymeric, metallic or glass beads in random arrays or in fluid suspension have used a variety of entities to provide coded elements (bits)--fluorescent molecules, molecules with specific vibrational signatures, quantum dots, or discrete metallic layers. Here we report a method for optically encoding micrometre-sized nanostructured particles of porous silicon. We generate multilayered porous films in crystalline silicon using a periodic electrochemical etch. This results in photonic crystals with well-resolved and narrow optical reflectivity features, whose wavelengths are determined by the etching parameters. Millions of possible codes can be prepared this way. Micrometre-sized particles are then produced by ultrasonic fracture, mechanical grinding or by lithographic means. A simple antibody-based bioassay using fluorescently tagged proteins demonstrates the encoding strategy in biologically relevant media.     

Efficient and robust multiphoton data storage in molecular glasses and highly crosslinked polymers

As electronics become ever faster and more powerful, there is growing interest in three-dimensional laser-based optical data storage techniques, which can potentially provide efficient storage at densities significantly higher than those that are likely to be available from magnetic media. The development of inexpensive, efficient and robust media has been a major obstacle in optical data storage. However, we have discovered a class of materials that become highly fluorescent on multiphoton absorption of pulses of 800-nm light from a Ti:sapphire oscillator, making them excellent candidate storage media. The materials are inexpensive, of high optical quality, can be processed readily, and can take a number of useful forms, including molecular glasses and highly crosslinked polymers. Three-dimensional data can be stored at high densities in these materials, and are highly robust to readout.     

Optical properties of the synthetic nanocomposites SiO2/CdS/poly(styrene-co-maleic anhydride) and SiO2/CdS/poly(styrene-co-maleimide)

Hybrid materials consisting of SiO2/CdS particles dispersed in poly(styrene-co-maleic anhydride) and poly(styrene-co-maleimide) have been synthesized and characterized. The polymer nanocomposites were synthesised in situ in the presence of previously prepared inorganic fillers (SiO2/CdS). The nanocomposites were synthesized with the use of as-prepared or surface-modified SiO2/CdS fillers. For both types of nanocomposites, the optical properties were evaluated and the observation of size quantization effects in the optical spectra is discussed. In this context, the influence of the inorganic fillers and polymer matrices on the optical properties of the final nanocomposites was investigated.     

In vitro adhesion and biocompatability of osteoblast-like cells to poly(methylmethacrylate) and poly(ethylmethacrylate) bone cements

A bone cement, poly(ethylmethacrylate)/n-butylmethacrylate (PEMA/nBMA) has been developed with lower exotherm and monomer leaching compared to the traditional poly(methylmethacrylate)/methylmethacrylate (PMMA/MMA) cement. This study compares the in vitro biological response to the cements using primary human osteoblast-like cells (HOB). Cell attachment was qualified by immunolocalization of vinculin and actin cytoskeleton, showing more organization on PEMA/nBMA compared to PMMA/MMA. Proliferation was assessed using tritiated thymidine incorporation, and phenotype expression determined by measuring alkaline phosphatase (ALP) activity. An increase in proliferation and ALP activity was observed on PEMA/nBMA compared to PMMA/MMA. The results confirm the biocompatability of PEMA/nBMA, and an enhanced cell attachment and expression of differentiated cell phenotype.