Ultrasonographic findings in cows with left displacement of abomasum, before and after reposition surgery.

Background: The natural incidence of left displacement of abomasum (LDA) in dairy cows was high. The diagnosis of LDA usually relies on characteristic physical exam findings but that transabdominal ultrasound is a useful technique that has been applied to the diagnosis of gastrointestinal diseases of dairy cows in equivocal cases.

Methods: Forty dairy cows with LDA were clinically and ultrasonographically examined to determine the position and the echogenic property of the abomasum.

[Effects of drought stress on performance of photosystem II in maize seedling stage].

Maize cultivar Shandan 609 was used to determine the effects of drought stress on photosystem II, dry matter accumulation, protective enzyme activity and proline content at seedling stage in pot experiment. Two drought treatments (moderate drought and severe drought) were tested. The results showed that dry matter accumulation, leaf area and plant height of cultivar shaandan 609 decreased significantly with the increasing drought stress.

[Effects of low nitrogen stress on source-sink characters and grain-filling traits of different genotypes summer maize].

This paper studied the source-sink characters and grain-filling traits of six genotype summer maize varieties under 2 years (from 2007 to 2008) application of low dosage (105 kg x hm(-2)) and normal dosage (337.5 kg x hm(-2)) fertilizer nitrogen. Under low nitrogen stress, the population yield, leaf area index (LAI), source-sink characters, and grain-filling traits of test varieties differed significantly.

[Spatial variability characteristics of soil organic carbon and nitrogen reveal typical alpine meadow degradation on Qinghai-Tibetan Plateau].

The principle of geo-statistics method was used to analyse the spatial heterogeneity of soil organic carbon and total nitrogen (0-10 cm) of alpine meadow of the Qinghai-Tibetan Plateau. The results show that the mean contents of soil organic carbon and total nitrogen at depth 0-10 cm are 11.45 g x kg(-1) and 1.

[Effects of planting date and density on population physiological indices of summer corn (Zea mays L.) in central Shaanxi irrigation area].

By using D-saturation optimum design and the methods of crop population physiology, this paper studied the effects of planting date and density on the population physiological indices of summer maize Shandan 8806 and its yield in central Shaanxi irrigation area. The results showed that in the period from 13 June to 22 July, the delay of planting had negative effects on grain yield, dry matter accumulation (DMA), maximum leaf area index (LAImax), net assimilation rate (NAR), leaf area duration (LAD) and crop growth rate (CGR), with larger effects on LAD and CGR than on LAImax and NAR. Within the range of 45 000-65 918 plants .