Follicular Dynamics in Heifers during Pre-pubertal and Pubertal Period Kept under Two Levels of Dietary Energy Intake

The objective of this study was to characterize follicular dynamics in pre-pubertal, pubertal and post-pubertal periods, as well as the effect of high-energy intake on follicular development and age at puberty in heifers. Thirty-one Nelore (Bos indicus) heifers, 6 months old, were randomly assigned to receive two different diets: one of low (GI) and other of high dietary energy intake (GII). Animals were evaluated in relation to body weight gain by being weighed every 21 days. Heifers were evaluated every other day by real-time linear ultrasonography to characterize ovarian structures development from weaning to post-pubertal period. Blood samples were collected to determine plasmatic concentrations of progesterone by RIA method. The ovulation was determined when progesterone concentrations were >1 ng/mL in three consecutive samples, and by ultrasound images of corpus luteum; and oestrous behaviour in some animals. Age at puberty differed among heifers of GII (17.00 +/- 0.46 months) compared with heifers of GI (19.87 +/- 0.47 months; p < or = 0.05). Maximum size of the dominant follicles at pre-pubertal period was greater in GII heifers than in GI (10.52 +/- 0.33 and 9.76 +/- 0.15 mm, respectively; p < or = 0.05). As heifers approached first ovulation time, size of dominant follicle increased (11.75 +/- 0.37 mm for GI and 12.52 +/- 0.91 mm for GII; p < or = 0.05). Body weight at puberty was not different in both groups (302.33 +/- 27.31 kg for GI and 326.19 +/- 27.78 kg for GII heifers; p > 0.05). We conclude that animals receiving high dietary energy intake attained the puberty earlier and the development of follicles were different than in low dietary energy intake.     

Pregnancy Loss in Dairy Cattle: Relationship of Ultrasound,Blood Pregnancy‐Specific Protein B,Progesterone and Production Variables

Objectives were to determine associations between percentage pregnancy loss (PPL) in dairy cattle and: (i) pregnancy diagnosis by ultrasonography; (ii) pregnancy diagnosis by serum pregnancy‐specific protein B (PSPB) concentrations, with or without serum progesterone concentrations; and (iii) production and environmental factors. This study included 149 822 pregnancy diagnoses conducted over 13 years in Holstein‐Friesian cows in Hungarian dairy herds. The following were determined: PPL in cows diagnosed pregnant by transrectal ultrasonography 29–42 days after artificial insemination (AI; n = 11 457); PPL in cows diagnosed pregnant by serum PSPB 29–35 days after AI (n = 138 365); and PPL and its association with serum progesterone concentrations, PSPB and production/environmental variables. The definition of PPL was percentage of cows initially diagnosed pregnant based on ultrasonography or PSPB, but not pregnant when examined by transrectal palpation 60 –70 days after AI. The PPL was lower (p < 0.001) in cows following ultrasonographic vs PSPB diagnosis of pregnancy at 29–35 days (8.1 vs 19.3%, respectively), but was higher in cows following ultrasonographic pregnancy diagnosis on 29–35 vs 36–42 days (8.1 vs 7.1%, respectively, P < 0.05). Furthermore, 72.9% of pregnancies with ultrasound‐detected morphological abnormalities resulted in pregnancy loss. As a subset of PSPB data, a fully quantitative PSPB assay was used for 20 430 samples; PPL in cows with a high PSPB concentration (>1.1 ng/ml) was lowest (15.0%), whereas cows with low concentrations of both PSPB and progesterone (0.6–1.1 and <2 ng/ml, respectively) had the highest PPL (76.3%; p < 0.0001). Furthermore, PPL was higher in cows with advanced parity and with high milk production, when ambient temperatures were high, although body condition score (BCS) had no effect on PPL. Finally, there were no significant associations between serum PSPB and environmental temperatures or number of post‐partum uterine treatments.     

Tracking the evolution of a hydrothermal event plume with a RAFOS neutrally buoyant drifter

The migration and evolution of a deep ocean hydrothermal event plume were tracked with a neutrally buoyant RAFOS float. The float remained entrained in the plume for 60 days, and the plume vorticity was calculated directly from the anticyclonic motion of the float. Concentrations of suspended particles, particulate iron, and dissolved manganese in the plume did not decay significantly during the 60 days, which indicates that event plumes would be easily detectable a year after formation.     

带拉杆的U形壳槽槽身横向内力计算有关问题的分析

在U形壳槽横向内力计算中,若不考虑槽底局部加厚对Φ=90°截面内力的影响,则计算所得的该截面弯矩绝对值偏小.温度变化对截面内力的影响较大,特别是温降引起多数截面的弯矩增加,而轴向力减少;温升引起Φ=90°截面弯矩与轴向拉力均增加,再考虑槽底局部加厚的影响,弯矩值还要增加.槽底局部加厚与温度变化的作用均不能忽略不计,否则,内力计算成果值会偏于不安全.用结构力学方法,推导出二者对内力影响的计算公式,并附有应用的算例.     

The efficacy of insecticides against the screw-worm fly (Chrysomya bezziana)

A number of insecticides used for ectoparasite control in the livestock industry were screened for their efficacy against larvae of the screw-worm fly, Chrysomya bezziana, using in vivo and laboratory tests. Proprietary screw-worm fly treatments (after exposure to outdoor conditions for up to 10 days) were also tested against eggs and adults of C bezziana. Three of these were also evaluated on naturally acquired screw-worm infestations. Residual protection was generally of short duration. Among the organophosphorus compounds, the most effective formulations contained relatively high concentrations (3 to 4% al) of coumaphos, 2.5% fenchlorphos or low concentrations (0.05 to 0.5% al) of diazinon, chlorfenvinphos and fenthion methyl. Two chlorinated hydrocarbon insecticides containing 3% lindane and 5% dieldrin were very effective but are now prohibited for use in Australia. Preparations had serious deficiencies when used under field conditions, especially for treating large, deepseated myiases for which systemic insecticides are recommended. A comparison of methods demonstrated that a laboratory test could supersede live animal experimentation, at least for the initial screening of potential insecticides.