Methane production,nutrient digestion,ruminal fermentation,N balance,and milk production of cows fed timothy silage- or alfalfa silage-based diets

The objective of this study was to investigate the effects of changing forage source in dairy cow diets from timothy silage (TS) to alfalfa silage (AS) on enteric CH₄ emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio of 60:40, dry matter basis), with the forage portion consisting of either TS (0% AS; 0% AS and 54.4% TS in the TMR), a 50:50 mixture of both silages (50% AS; 27.2% AS and 27.2% TS in the TMR), or AS (100% AS; 54.4% AS and 0% TS in the TMR). Compared with TS, AS contained less (36.9 vs. 52.1%) neutral detergent fiber but more (20.5 vs. 13.6%) crude protein (CP). In sacco 24-h ruminal degradability of organic matter (OM) was higher for AS than for TS (73.5 vs. 66.9%). Replacement of TS with AS in the diet entailed increasing proportions of corn grain and bypass protein supplement at the expense of soybean meal. As the dietary proportion of AS increased, CP and starch concentrations increased, whereas fiber content declined in the TMR. Dry matter intake increased linearly with increasing AS proportions in the diet. Apparent total-tract digestibility of OM and gross energy remained unaffected, whereas CP digestibility increased linearly and that of fiber decreased linearly with increasing inclusion of AS in the diet. The acetate-to-propionate ratio was not affected, whereas ruminal concentration of ammonia (NH₃) and molar proportion of branched-chain VFA increased as the proportion of AS in the diet increased. Daily CH₄ emissions tended to increase (476, 483, and 491 g/d for cows fed 0% AS, 50% AS, and 100% AS, respectively) linearly as cows were fed increasing proportions of AS. Methane production adjusted for dry matter intake (average = 19.8 g/kg) or gross energy intake (average = 5.83%) was not affected by increasing AS inclusion in the diet. When expressed on a fat-corrected milk or energy-corrected milk yield basis, CH₄ production increased linearly with increasing AS dietary proportion. Urinary N excretion (g/d) increased linearly when cows were fed increasing amounts of AS in the diet, suggesting a potential for higher nitrous oxide (N₂O) and NH₃ emissions. Efficiency of dietary N use for milk protein secretion (g of milk N/g of N intake) declined with the inclusion of AS in the diet. Despite marked differences in chemical composition and ruminal degradability, under the conditions of this study, replacing TS with AS in dairy cow diets was not effective in reducing CH₄ energy losses.     

Effect of bisphosphonates on the stimulation of macrophages by alumina ceramic particles: A comparison with ultra-high-molecular-weight polyethylene

Wear particle-induced osteolysis and loosening is a critical process that limits the longevity of total hip arthroplasty. Despite their potential value in the management of aseptic loosening, little is known about the cellular response to bisphosphonates (BPs) in the presence of particulate debris. In the present study, we compared the effect of pamidronate and clodronate, two structurally different bisphosphonates, on the induction of TNF-α release by alumina ceramic (Al₂O₃) and ultra-high-molecular-weight-polyethylene (UHMWPE) particles. We also looked, by Trypan blue exclusion, at the viability of J774 mouse macrophages incubated with Al₂O₃ and UHMWPE particles in combination with pamidronate or clodronate. Results showed that pamidronate and clodronate can inhibit UHMWPE particle-induced TNF-α release while they had no effect on Al₂O₃-stimulated TNF-α release. The co-incubation of pamidronate or clodronate and Al₂O₃ had no effect on the induction by Al₂O₃ of poly(ADP-ribose)polymerase (PARP) proteolysis and DNA fragmentation. On the other hand, UHMWPE particles had no effect on these apoptotic markers. However, the co-incubation of pamidronate or clodronate with UHMWPE particles led to the appearance of these markers of apoptosis. Al₂O₃ and UHMWPE particles had no effect on macrophage cell death or the number of macrophages at the end of experiments. Co-incubation of UHMWPE particles with pamidronate and clodronate led to a significant increase in cell death. Interestingly, the number of macrophages co-incubated with particles and pamidronate or clodronate significantly decreased. In conclusion, our results suggest that the effect of BPs on particle-stimulated macrophages is, at least in part, particle composition dependent.     

Characterization of Staphylococcus aureus strains associated with food poisoning outbreaks in France

Enterotoxins produced by Staphylococcus aureus are responsible for staphylococcal food-poisoning outbreaks (SFPO). In France, SFPO are the second cause of food-borne diseases after Salmonella. However, very little is known about the strains involved. The objective of this study was to characterize the staphylococcal strains related to these SFPO through phenotypic and genotypic analyses. A total of 178 coagulase-positive staphylococcal isolates recovered from 31 SFPO (1981-2002) were screened through biotyping. Thirty-three strains representative of the different biotypes in each SFPO were further examined for SmaI macrorestriction-type, phage-type, resistance to various antimicrobial drugs, presence of staphylococcal enterotoxin (se) genes sea to sei, and production of enterotoxins SEA to SED. All these 33 strains were identified as S. aureus species: 27 were of human biotypes and six ovine or non-host-specific biotypes. Most (74.1%) strains reacted with group III phages. Eleven strains were resistant to at least two classes of antibiotics and among them, two were resistant to methicillin. Twenty-nine strains carried one or several of the eight se genes tested; the gene sea was most common (n=23), and often linked to sed (n=12) or seh (n=5). The novel se genes seg-i were in all cases associated with se genes sea to sed except for one strain which carried only seg and sei. Pulsed-Field Gel Electrophoresis (PFGE) of SmaI macrorestriction digests of the 33 strains discriminated 32 PFGE patterns grouped into nine biotype-specific clusters. All five strains carrying sea and seh were grouped together into the same sub-cluster. Three of the four se-gene-negative strains were in one PFGE cluster: all four should be tested for se genes not included in this study and, if negative, be further investigated for the presence of unidentified SEs.     

Effect of feeding whole, unprocessed sunflower seeds and flaxseed on milk production, milk composition, and prostaglandin secretion in dairy cows

Four multiparous Holstein cows were used in a 4 x 4 Latin-square design experiment to study the effects of different fat sources on milk production and composition, N utilization, follicular development, and prostaglandin secretion. Cows were fed 4 total mixed rations (TMR) based either on calcium salts of palm oil (Megalac), whole flaxseed, whole sunflower seed, or no supplementary fat (control). Feed intake and digestibilities were generally similar among treatments, except that ether extract digestibility was the lowest for cows fed the control diet. Milk yields were greater for cows fed whole flaxseed and Megalac (32.1 and 31.5 kg/d, respectively) than for those fed sunflower seed and control (25.9 and 24.8 kg/d, respectively). Milk protein concentration was significantly lower for cows fed Megalac (3.68%) compared with those fed flaxseed (3.87%) or control (3.92%). Concentrations of n-3 fatty acids and the n-6 to n-3 fatty acids ratio in milk were the highest and lowest, respectively, for cows fed whole flaxseed. There was an interaction between treatment and time for levels of 13,14-dihydro-15-keto-PGF(2alpha) in plasma; they were greater 30 and 45 min after the oxytocin challenge for cows that were fed sunflower seed compared with those fed either Megalac, flaxseed, or control. Moreover, when concentrations of 13,14-dihydro-15-keto-PGF(2alpha) in plasma were expressed as the area under the overall response curve from 0 to 120 min after the oxytocin injection, it tended to be greater for cows that were fed the sunflower diet compared with those fed either Megalac or flaxseed. In general, follicle dynamics were similar among treatments. These results suggest that feeding diets with high proportions of n-6 fatty acids (61% of total fatty acids for the sunflower seed diet) tended to increase the secretion of series 2 prostaglandins in blood.     

Influence of storage environment on maize grain: CO2 production,dry matter losses and aflatoxins contamination

Poor storage of cereals, such as maize can lead to both nutritional losses and mycotoxin contamination. The aim of this study was to examine the respiration of maize either naturally contaminated or inoculated with Aspergillus flavus to examine whether this might be an early and sensitive indicator of aflatoxin (AF) contamination and relative storability risk. We thus examined the relationship between different interacting storage environmental conditions (0.80–0.99 water activity (a_w) and 15–35°C) in naturally contaminated and irradiated maize grain + A. flavus on relative respiration rates (R), dry matter losses (DMLs) and aflatoxin B1 and B2 (AFB1-B2) contamination. Temporal respiration and total CO₂ production were analysed by GC-TCD, and results used to calculate the DMLs due to colonisation. AFs contamination was quantified at the end of the storage period by HPLC MS/MS. The highest respiration rates occurred at 0.95 a_w and 30–35°C representing between 0.5% and 18% DMLs. Optimum AFs contamination was at the same a_w at 30°C. Highest AFs contamination occurred in maize colonised only by A. flavus. A significant positive correlation between % DMLs and AFB1 contamination was obtained (r = 0.866, p < 0.001) in the irradiated maize treatments inoculated with A. flavus. In naturally contaminated maize + A. flavus inoculum loss of only 0.56% DML resulted in AFB1 contamination levels exceeding the EU legislative limits for food. This suggests that there is a very low threshold tolerance during storage of maize to minimise AFB1 contamination. This data can be used to develop models that can be effectively used in enhancing management for storage of maize to minimise risks of mycotoxin contamination.     

Abnormal XY interchange between a novel isolated protein kinase gene, PRKY, and its homologue, PRKX, accounts for one third of all (Y+)XX males and (Y-)XY females

XX males and XY females have a sex reversal disorder which can be caused by an abnormal interchange between the X and the Y chromosomes. We have isolated and characterized a novel gene on the Y chromosome, PRKY. This gene is highly homologous to a previously isolated gene from Xp22.3, PRKX, and represents a member of the cAMP-dependent serine threonine protein kinase gene family. Abnormal interchange can occur anywhere on Xp/Yp proximal to SRY. We can show that abnormal interchange happens particularly frequently between PRKX and PRKY. In a collection of 26 XX males and four XY females, between 27 and 35% of the interchanges take place between PRK homologues but at different sites within the gene. PRKY and PRKX are located far from the pseudoautosomal region where XY exchange normally takes place. The unprecedented high sequence identity and identical orientation of PRKY to its homologous partner on the X chromosome, PRKX, explains the high frequency of abnormal pairing and subsequent ectopic recombination, leading to XX males and XY females and to the highest rate of recombination outside the pseudoautosomal region.     

Characterization of biodegradable core–clad borosilicate glass fibers with round and rectangular cross-section

Here, we report on core–clad bioactive borosilicate fibers, that we have prepared both with round and rectangular cross-section profile. The exposed approach, which relies on the stacking and drawing of glass slabs, demonstrates our ability to develop bioactive-based glass fibers with tailored cross-section profiles. Tens-of-meters-long fibers were successfully drawn, although suffering from elevated losses in the case of the rectangular ones. The response of the fibers in simulated body fluid was studied for both geometries. We found that a round cladding can act as protective layer, tempering effects of the corrosion. We also noticed that rectangular fibers are more prone to degradation, the enhanced corrosion beginning from their sharp corners as they accumulated residual tensile stress during drawing. To the best of our knowledge, this is the first report on the effect of residual tensile stresses from surface tension deformations applied to the corrosion of rectangular fibers. As geometry plays a critical role on the biodegradation behavior of the fiberglass, we believe the enclosed results could lead to the design of fiber devices with tailored cross-section profile in order to tune their rate of degradation on solely based geometrical effects.