Salmonella gona infection in sheep

A field outbreak of salmonellosis due to Salmonella agona in sheep and some subsequent experimental work is described. While the field outbreak in pregnant ewes and neonatal lambs caused severe losses the experimental disease in non-pregnant sheep was mild and transient. S agona was not isolated from the carcases of the experimental sheep killed after 28 days post infection but it persisted for 69 days in the faeces of one ewe which was kept alive for three months. Media comparisons indicated that selenite enrichment broths incubated at 43 degrees C and plated on to brilliant green agar gave the most satisfactory cultural results.     

Radiographic assessment of pulmonary fluid clearance and lung aeration in newborn calves delivered by elective Caesarean section

The aim of this study was to develop a radiographic standard for the assessment of pulmonary fluid clearance and lung aeration in newborn calves. Caesarean‐delivered mature calves (n = 9) underwent lung assessment by thoracic radiography as well as arterial and venous blood gas analysis within the first 30 min, 1, 2, 3, 6, 12 and 24 hr after birth. The results indicated that newborn calves delivered by elective Caesarean section suffered from a physiological combined respiratory and metabolic acidosis with the dominance of respiratory acidosis, and an improvement in these conditions was recorded within 24 hr after birth. Concerning the radiographic results, clear lung fields, improvement in lung expansion, air content of the lung and absence of lung opacification occurred within 24 hr of birth. Furthermore, the ventral lung quadrant showed an improvement in radiographic opacification and lung expansion earlier than the dorsal lung regions. The findings of this study support the potential role of thoracic radiography in the assessment of pulmonary fluid clearance and lung aeration in newborn calves.     

Effect of oestrous synchrony between embryo donors and recipients,embryo quality and state on the pregnancy rate in beef cattle

This study aimed to evaluate the effect of oestrous synchrony between donors and recipients and the embryo quality on the pregnancy rate in beef cow recipients. The experiment was performed over two years at an embryo transfer (ET ) centre in Southern Brazil. Ninety Aberdeen Angus cows were subjected to superovulation (SOV ) protocols, resulting in the recovery of 1,048 transferable embryos. Eleven groups were formed with intervals of 6 hr, from ?30 to +30 hr, with respect to recipient versus donor oestrous detection. Evaluation of embryo quality was according to the IETS guidelines. The overall pregnancy rate was 52%. Effects related to donor and recipient oestrous synchronization on pregnancy rate were observed (p  =  .01), ranging from 36% to 50%. The embryo quality rate affected the pregnancy rate, where Grade I resulted in 57% and Grade III in 43% of pregnancy (p  <  .001). The embryonic state (frozen or fresh) showed no (p  >  .05) effect on pregnancy rate: 53% for fresh embryos and 44% for frozen embryos. The odds ratio for explanatory variables causing pregnancy indicated that Grade III embryos had 31% less chance of conception compared to Grade I. Thus, oestrous synchrony between donor and recipient, considering ±30 hr apart, can affect the pregnancy rate along with embryo quality.     

Indications and implications for testing of milk urea in dairy cattle: a quantitative review. Part 2. Effect of dietary protein on reproductive performance

DIETARY PROTEIN AND DAIRY COW FERTILITY: Feeding more dietary protein has been negatively associated with dairy cow fertility in some but not all studies. We used meta-analysis to examine the relationship between dietary crude protein and conception rate. While a higher intake of dietary crude protein significantly lowered conception rate, the potential for feeding less degradable dietary protein to modify this relationship was not demonstrated. MILK UREA CONCENTRATIONS AND DAIRY COW FERTILITY: The use of milk urea as an indicator of dietary energy and protein intake and as an indicator of reproductive performance has been questioned. We found that changes in urea concentration in body fluids explained only 25% (p = 0.08) of the variance in conception rate after conducting a meta-analysis of available studies. INTERPRETATION OF MILK UREA CONCENTRATIONS: High intakes of dietary protein may induce adaptations in urea metabolism, and the negative relationship identified between high intakes of dietary protein and fertility for Northern Hemisphere dairy herds may not necessarily apply in Australasian dairy herds. Because of the potential for cows to adapt to high protein diets, the use of a single milk urea determination on a herd will have limited value as an indicator of nutritional status and little value as a predictor of fertility.     

Chlamydia abortus in Cows Oviducts,Occasional Event or Causal Connection?

Fifty‐seven genital tracts of regularly slaughtered culled Piedmontese cows, aged 7.4 ± 4.3 years (mean ± SD), range: 2.6–15.6 years, were grossly and microscopically examined. DNA extracted from oviducts was subjected to PCR to evaluate the presence of Chlamydia spp. The 15 PCR‐positive oviducts were subjected to Sanger sequencing and showed the presence of Chamydia abortus, with an identity range between 99 and 100%. Nine of the PCR‐positive samples belonged to the 24 animals with a normal macroscopic appearance of the whole genital tract (percentage of positive oviducts in normal genital tracts 9/24 = 37.5%), while six belonged to the 33 genital tracts with lesions in one or more organs (percentage of positive oviducts in pathological genital tracts 6/33 = 18.1%); of these, a single animal had salpingitis. The detection of C. abortus in bovine oviducts is of particular interest because it has never been previously investigated or reported.     

克伦特罗和生长激素对猪的生长及胴体组成的影响

将 36头试验猪分成 4组 :β 肾上腺素能激动剂处理组即克伦特罗处理组 (1kg饲料添加克伦特罗 3mg ,连续 2 8d)、生长激素处理组 (按 1kg体重每日注射 0 1mg生长激素 ,连续 2 1d)、克伦特罗和生长激素混合处理组及空白对照。试验结束后 ,测定猪的胴体组成 ,结果表明 :克伦特罗处理组和生长激素处理组的日增重分别比对照组提高 17%和 19% ,而混合处理组的日增重则下降 38% ,饲料摄入量下降 39% ;克伦特罗处理组背最长肌面积增加 19% ,背膘厚下降 2 3% ,与之相比 ,生长激素能加强猪的基础合成代谢 ,因而胴体成分没有明显改变 ;克伦特罗和生长激素混合处理组的活重减轻 ,胴体和内脏的比例下降 ,胴体明显瘦于对照组 ,但最长肌面积相等。结果还表明 β 肾上腺素能激动剂和生长激素对猪的饲料摄入量和胴体组成有互作效应 ,有关机理还需进一步研究。     

Antagonistic effect of soil rhizosphere microorganisms on Bipolaris sorokiniana,the causal agent of wheat seedling blight

The biocontrol efficiency of Epicoccum purpurascens, Gliocladium roseum, three strains of Bacillus subtilis, and Pseudomonas fluorescens, isolated from the rhizosphere of wheat plants, was assessed in relation to seedling blight caused by Bipolaris sorokiniana. An in vitro study of the potential antagonist was performed using the dual culture technique and by ‘sowing’ wheat seeds pelleted with the saprophytes in plates with water agar?+?the pathogen. In vivo assays were carried out in the greenhouse and in the field with pelleted seeds sown in artificially infested soil. Both the number of living plants and the number of plants with necrosis on the leaves and the base of the stems and roots were assessed 15 days after sowing. Under greenhouse conditions, B. subtilis 3 and G. roseum reduced the level of infection of Buck Pucará and Trigomax 100 cultivars, respectively. In the field, biocontrol of the disease was not achieved.     

Livestock disease threats associated with intensification of pastoral dairy farming

This paper provides an overview of the changes in the pasture-based dairy systems of New Zealand and Australia that may influence the health of cattle.

There are relatively few available data that can be used to quantify the effects of increased intensification of milk production on the health of cattle. There is evidence that increased production increases the risk of mastitis and culling for udder health. Increased risks of mastitis with treatment with somatotropin support these findings; however, the risk of mastitis may decrease with increased milking frequency. Larger herds with greater stocking density should increase the risk for infectious disease, but evidence to support this contention is sparse.

Very intensive grazing patterns associated with higher grass yields achieved using better cultivars and greater use of fertilisers favour nematode parasites. There is some evidence of anthelmintic resistance in both nematodes and liver fluke. Veterinarians will need to be aware of the potential for these to reduce the productivity of cattle.

There have been benefits of improved nutrition on the efficiency of energy use for dairy production. Diseases such as bloat and ketosis appear to be of lower prevalence. It also appears that mineral nutrition of pasture-fed cattle is being better addressed, with gains in the control of milk fever, hypomagnesaemia and trace-element deficiencies. However, acidosis is a condition with a high point prevalence in pasture-based dairy systems where cows are fed supplements; one study in Australia found a point prevalence of approximately 11% of cows with acidosis. There is evidence from this study that the neutral detergent fibre (NDF) in pasture-based diets may need to be higher than 30% of the diet to maintain rumen stability. Laminitis and acidosis are different conditions with a similar pathogenesis, specifically highly fermentable diets. The prevalence of lameness was 28% in herds in Australia, suggesting that this condition must be a focus for preventive medical approaches, including the design of laneways, feedpads and dairies.     

Critical thermal maxima and minima for curimbatá, Prochilodus scrofa Steindachner, of two different sizes

Critical thermal maxima (CTMax) and minima (CTMin) were determined for Prochilodus scrofa Steindachner of two sizes (19.5 ±7.2 g and 249 ± 42.4 g). acclimated at 15. 20, 25, 30 and 35 ± 1°C. The CTMax and the CTMin for the smaller fish were 33.9. 36.7. 38.7, 40.3. 42.0°C and 5.0, 7.2. 9.2. 10.3. 13.4^oC and for the larger (Ish 33.3, 35.7, 38.2. 40.6. 42.6°C and 6.5, 8.2. 10.8. 12.4, 14.6°C. respectively, at each acclimation temperature. The CTMin from smaller fish were significantly lower than those from larger ones but the CTMax did not show any such difference. These results indicate that P. scrofa is suitable for culture in south-eastern and even in southern Brazil where winter temperatures may drop to very low levels, mainly at night. The zone of thermal tolerance calculated by CTMax and CTMin was equivalent to 1046°C² and 964.2°C², respectively, for smaller and larger fish, showing a high degree of eurythermicity.