DDGS和酵母培养物对奶牛生产性能和乳成分的影响

选择16头泌乳天数为127±52d经产荷斯坦泌乳牛用于评价酵母培养物(达农威益康XP)和玉米酒糟及其可溶物(DDGS)在试验日粮中含有限草料纤维数量(草料中的中性洗涤纤维含量为19.3%,干物质基础)之情况下对产奶量和乳成分的影响及其它们之间的互作效应。本次试验采用4重复4×4拉丁方设计,试验时间为4个星期。处理组均按照2×2因子排列而设定,其中:1)日粮中不含酵母培养物和DDGS(对照组);2)日粮中含有20%DDGS,无酵母培养物(DDGS组);3)日粮中含有60g/d的酵母培养物益康XP(XP组);4)日粮中含有20%DDGS和60g/d的益康XP(XP+DDGS组)。本次试验结果表明:各处理组之间对奶牛体重和体况评分无显著的影响。日粮的处理并不影响干物质采食量(DMI),在使用草料纤维含量较低且添加20%DDGS的日粮情况下乳脂率会降低。添加益康XP的确能够提高产奶量及乳蛋白产量,但却不能够完全阻止因DDGS所造成的乳脂率下降的趋势。无论日粮中是否含有DDGS,益康XP都能够提高奶牛的生产性能。     

The spread of Corynebacterium pseudotuberculosis infection to unvaccinated and vaccinated sheep

SUMMARY The decrease in the prevalence of Corynebacterium pseudotuberculosis after two generations of vaccination against the disease it causes, was used to estimate the rate of control of caseous lymphadenitis (CLA). Three groups of 150 sheep, of which 50 in each group were artificially infected with C pseudotuberculosis and 100 in each group were uninfected sheep, were run separately for 40 months and shorn 5 times to promote the spread of CLA. One lot of 50 infected sheep and 2 lots of 100 uninfected sheep were vaccinated against CLA. The rate of spread of CLA was recorded. Sheep vaccinated against CLA and naturally exposed to infection had a 74% lower infection rate than unvaccinated sheep. Sheep vaccinated against CLA and exposed to only vaccinated infected sheep had a 97% lower infection rate. Unvaccinated sheep had a 76% infection rate, with 77% of the transmission occurring at the 4th and 5th shearings, without any discharging CLA abscesses being observed. This study supports the view that in Australian wool producing flocks, CLA spreads mainly from sheep with discharging lung abscesses to sheep with shearing cuts. Vaccinated sheep infected with CLA have 96% fewer lung abscesses compared with unvaccinated infected sheep and are therefore less likely to spread this disease to other sheep .     

New infection with Corynebacterium pseudotuberculosis reduces wool production

SUMMARY The effect of natural Corynebacterium pseudotuberculosis infection on wool production and quality in sheep was examined in light of evidence that artificial C pseudotuberculosis infection causes wool production loss. A toxin ELISA was used to identify sheep that had been infected with C pseudo tuberculosis. Greasy and clean fleece weights and fibre diameter were compared in infected and uninfected sheep. C pseudotuberculosis infection caused a 3.8 to 4.8% decrease in greasy wool production and a 4.1 to 6.6% decrease in clean wool production. C pseudotuberculosis infection did not affect fibre diameter. The effects of caseous lymphadenitis (the disease caused by C pseudotuberculosis infection) cause an annual loss of about $17 million in wool production to the Australian wool industry.     

Challenges to controlling rabies in skunk populations using oral rabies vaccination: A review

Controlling rabies in skunk populations is an important public health concern in many parts of the United States due to the potential for skunk rabies outbreaks in urban centres and the possible role for skunks in raccoon rabies variant circulation. Oral rabies vaccination (ORV) programmes have supported wildlife rabies control efforts globally but using ORV to control rabies in skunk populations has proven more challenging than with other target species, like foxes, coyotes and raccoons. A review of published studies found that some ORV constructs are immunogenic in skunks and protect against virulent rabies virus challenges, especially when delivered by direct installation into the oral cavity. However, in field ORV programmes using currently available vaccine‐bait formats and distribution methods targeting other rabies reservoir species, skunks often fail to seroconvert. Field effectiveness of ORV in skunks appears to be limited by poor bait uptake or inadequate ingestion of vaccine rather than from poor vaccine efficacy. Observations of captive skunks revealed vaccine spillage when handling and biting into baits such that modification of bait formats might improve field effectiveness. In addition, a dose–response relationship between bait distribution density and post‐baiting seroconversion among skunks was observed across the limited number of field studies. Additional research is needed to identify opportunities to modify ORV baits and distribution strategies to improve the viability of ORV as a rabies control strategy in skunks.     

Growth environment and seedling age affect constitutive and inducible defence in radiata pine

There is increasing interest in induced resistance for crop protection. This study investigated effects of growth environment on inducible defences in developing radiata pine (Pinus radiata) seedlings. Seedlings were grown in the presence or absence of Trichoderma in either a temperature-controlled growth room or in a greenhouse. After 3, 5 or 7 months, seedlings were sprayed with 2.25 mm methyl jasmonate (MJ), 1 week before quantification of monoterpenes and total phenolics. The magnitude of induction of monoterpenes and total phenolics by MJ was inversely proportional to constitutive content, was greater in the greenhouse than the growth room and was greater at 3 months than at 7 months. This may indicate a cost-saving strategy to limit defence induction once constitutive defence reaches a certain threshold. Growth room seedlings expressed greater constitutive resistance to terminal crook (Colletotrichum acutatum) and to diplodia dieback (Diplodia sapinea) than greenhouse plants, consistent with the relative differences in constitutive defence chemistry. Indeed, while MJ induced resistance to diplodia dieback in both environments, there was no difference in terminal crook incidence (4.1%) between MJ-treated and untreated seedlings in the growth room. By the end of the study, growth room seedlings had c. 70% more β-pinene in stems and 140% more total phenolics in needles than greenhouse plants but were 40% smaller, indicating a defence–growth trade-off. Trichoderma did not have a significant effect on defence chemistry or on pathogen resistance. These results demonstrate the potential to manipulate defence in radiata pine by modification of the growth environment.