This study examined the effects of recombinant bovine tumor necrosis factor-alpha (rbTNF) administration on metabolic and hormonal responses and lactational performance in dairy cows. Twelve lactating Holstein cows were injected subcutaneously with rbTNF (2.5 microg per kg per d) or saline (3 ml per head per d) at 1200 h daily for 7 d (d 0-6) and used in a crossover design. The rbTNF treatment induced increases in plasma haptoglobin, nonesterified fatty acid, cortisol, and growth hormone levels compared with the control levels. The rbTNF-treated cows had lower triiodothyronine and insulin-like growth factor-1 concentrations than control cows. In a somatoliberin challenge on d 6, the somatotropin response to somatoliberin (0.25 microg/kg) was smaller in the rbTNF group than in the control. The rbTNF treatment also produced increases of the nitrite plus nitrate concentration in plasma and milk during the period between d 1 and 7. Milk yield was reduced by rbTNF administration from d 1 to 8. The percentage of milk fat was increased on d 1-7 by rbTNF treatment, but milk protein content in the rbTNF group was decreased on d 5 and 7 as compared with that in the control group. These results support the possibility that tumor necrosis factor-alpha is responsible for the changes in hormone secretion, milk production and composition, and inflammatory parameters observed during coliform mastitis.

Endotoxin induces marked changes in lipid metabolism via its effects on cytokines. To evaluate the role of tumor necrosis factor-alpha (TNF) in mediating changes of lipid metabolism in ruminants, we performed a crossover saline-controlled study in Holstein heifers (n = 8; 394.0 kg average BW), investigating the metabolic effects of a single intravenous administration of recombinant bovine TNF (rbTNF, 5.0 microg/kg). Blood samples were taken from a jugular vein at 0 (1100, just before injection), 0.5, 6, 12, and 24 h after each treatment. Dry matter intake in the heifers was not affected by single administration of the rbTNF. The rbTNF produced early as well as later hypertriglyceridemia (P < 0.05) in dairy heifers. The rbTNF also induced an early and sustained rise (P < 0.05) in the plasma NEFA concentration. Plasma retinol concentration was decreased (P < 0.05) at 24 h after rbTNF injection, whereas the a-tocopherol concentration was not significantly affected by rbTNF treatment. At 0.5 and 24 h, there was an increase (P < 0.05) in the plasma concentration of the very-low-density lipoprotein (VLDL) fraction in rbTNF-treated heifers. Between 6 and 24 h after rbTNF treatment, concentration of the low-density lipoprotein fraction declined (P < 0.05) but the high-density lipoprotein fraction was not altered in the rbTNF-treated heifers. These results indicate that TNF produces a hypertriglyceridemic response associated with an increase of the VLDL fraction and a disturbance of retinol metabolism in dairy heifers.

Aims:  To investigate the effects of inoculating Lactobacillus casei or Lacobacillus buchneri on the production of biogenic amines (BA) in silage. Methods and Results:  Wilted festulolium (Lolium perenne × Festuca pratensis), whole crop maize or a total mixed ration, consisting of wet brewer grains, lucerne hay, cracked maize, sugarbeet pulp, soyabean meal and molasses, was ensiled with or without the inoculation of either L. casei (>106 CFU g−1) or L. buchneri (>106 CFU g−1). Silages were opened after 60 days of storage, and the concentrations of histamine, tyramine, putrescine and cadaverine were determined. The inoculation of L. casei decreased all the BA regardless of the silage type. The effects of L. buchneri varied between the three silages; the tyramine and putrescine were increased in maize but were lowered in festulolium. Histamine was reduced in festulolium and the by‐products, whereas no change was found in the maize silage. None of the inoculant strains produced the four BA in a synthetic medium, accounting for the actual ensiling except for tyramine and putrescine in maize. Conclusions:  Wide variation would be found in the production of BA owing to the ensiling materials. The inoculation of L. casei can lower the BA concentration, while the effects of L. buchneri may vary considerably. The screening of BA‐producing activity may help to reduce the risk of BA contamination in inoculated silage. Significance and Impact of the Study:  Strains of decarboxylase‐negative L. buchneri can enhance the aerobic stability of silage without a concern regarding the large production of putrefactive BA.

Two experiments were conducted to study the effects of wilting and inoculating Lactobacillus casei or Lactobacillus buchneri on the fermentation and aerobic stability of grass silages. Chopped Italian ryegrass (IR) and Festulolium (FE) were ensiled with or without wilting and added L casei (>10 6 cfu g −1 fresh matter (FM)) or L buchneri (>10 6 cfu g −1 FM). Silos were opened after 120 days and microbial counts, fermentation products and aerobic stability were determined. Addition of L casei increased lactic acid and decreased acetic acid and dry matter loss regardless of wilting and forage species. Inoculation of L buchneri decreased lactic acid and increased acetic acid and 1,2-propanediol, while the effects appeared greater in direct-cut than in wilted grass silages. Although 1,2-propanediol accumulated in FE silage, the diol was degraded further to propionic acid and 1-propanol in IR silage. The activity of 1,2-propanediol degradation was lowered when IR was wilted prior to ensiling; 1,2-propanediol remained and the production of propionic acid and 1-propanol was less than one-third of that in direct-cut silage. Regardless of forage species, addition of L buchneri increased dry matter loss compared with the untreated control, whereas the loss was not significant in wilted silages. Ammonia production was increased by L buchneri in direct-cut but not in wilted silages. No heating was observed with or without inoculation in direct-cut IR silage after exposure to air. Other silages were deteriorated when L buchneri was not inoculated, while the spoilage was accelerated when L casei was added to FE.

White clover (Trifolium repens L.) living mulch, a cover crop cultivation system, has been shown to improve phosphorus (P) nutrition and increase the yield and arbuscular mycorrhizal colonization rate of the main crop without inoculation of fungi. However, it remains unclear whether the P uptake of corn (Zea mays L.) in living mulch is promoted directly by arbuscular mycorrhizal colonization. We performed a pot experiment to test the hypothesis that living mulch increases the P uptake of corn by promoting arbuscular mycorrhizal colonization. The experimental design was a 2 Â 2 factorial arrangement using fungicide treatment (fungicide application or no fungicide application) and cropping system (living mulch or no mulch). The fungicide dazomet was used to inhibit arbuscular mycorrhizal colonization. Without fungicide application, the P concentration and dry weight of the corn shoots were greater in the living mulch than in the no mulch treatment, indicating that living mulch improved the P nutrition and growth of corn. Fungicide application in living mulch, however, decreased the P concentration, dry weight of corn shoots, and arbuscular mycorrhizal colonization compared with no fungicide application. These results suggest that living mulch increases the P uptake of the main crop by promoting arbuscular mycorrhizal colonization by indigenous fungi.