Nutrient accumulation in leaf tissue of rapid‐cycling brassuca oleracea responds to increasing sodium selenate concentrations

Brassica oleracea L. are important economic vegetables, and are capable of selenium (Se) enrichment to enhance human nutrition and health. Because Se enrichment may influence the nutrient balance of this crop, a study was done to test the effects of selenate‐Se on plant nutrients. Plants of a rapid‐cycling B. oleracea population were grown in nutrient solutions amended with Na₂SeO₄at 0.0, 3.0, 6.0, and 9.0 mg L^‐1. Leaf tissue was then analyzed for nutrient content. Boron (B) (P=0.01), iron (Fe) (P=0.01), and phosphorus (P) (P=0.01) content decreased, while Se (P=0.01), sulfur (S) (P=0.01), and potassium (K) content (P=0.01) increased with increasing selenate‐Se treatments. Significant quadratic responses were found for magnesium (P=0.01) and molybdenum (P=0.01). No significant differences in leaf fresh or dry weight were detected. Changes in plant nutrient content can be expected when Brassicas are enhanced for delivery of beneficial organic Se.     

Analysis of BioOne Journal Collections: Their Quality,Indexing Coverage,and Scholarly Content

This study examined the 130 current full-text titles in the BioOne.1 and BioOne.2 collections to determine whether they are peer-reviewed, contain book reviews, and are supplied by document delivery vendors. We identified indexing coverage in 11 major databases in agriculture and life sciences: Aquatic Sciences and Fisheries Abstracts (ASFA), AGRICOLA, Biological Abstracts, BIOSIS Previews, CAB Abstracts, Current Contents, Environmental Sciences and Pollution Abstracts, GeoRef, Scopus, ISI Web of Science, and Zoological Record. We concluded that the majority of the titles in BioOne collections are refereed and scholarly, indexed in several of the major indexing and abstracting journals in the field of agriculture and life sciences, and available via several major document delivery vendors. We find both BioOne collections to be valuable, useful, cost-effective journal aggregations.     

Predicting yield and processing quality of potato breeding selections

The linear relationship between “site mean” and potato cultivar performance was used to develop predictive models for total yield, yield of US No 1 grade, per cent US No 1 grade, specific gravity and fried chip color. The best fitting linear expression for each of the traits was determined by linear regression for specific cultivars. Common limits for “site means” could then be substituted into the expressions for predictive purposes. Application of this method to large and small data sets demonstrated its use for interpreting preliminary yield trial information for the identification of superior breeding selections.     

Accumulation of 60Co and 134Cs in Lake Whitefish in a Canadian Shield Lake

Radionuclides were added to the anaerobic hypolimnion of a Canadian Shield lake during the summer of 1989 to simulate nuclear fuel waste leakage into the bottom waters of a lake with deep groundwater flow. Lake whitefish (Coregonus clupeaformis) were sampled in mid-October each year from 1989 to 1994, except for 1992, to determine the concentration of ⁶⁰and ¹³⁴Cs in their tissues. The radionuclides remained in the hypolimnion until lake mixing in the autumn. Subsequently, there was more loss of ⁶⁰than¹³⁴Cs from the water. After one year, 4% of the⁶⁰Co and 15% of the ¹³⁴Cs remained in the water. This decreased to about 0.4% of the ⁶⁰and 0.6% of the ¹³⁴Cs in the water after five years. Little ⁶⁰and ¹³⁴Cs were present in lake whitefish the first autumn following the radionuclide addition. In fish, the highest concentrations were recorded in October, 1990, after which concentrations gradually decreased. Cobalt-60 concentrations were lower than ¹³⁴Cs concentrations, probably because ⁶⁰has a high affinity for organic particles and was not available for uptake. The relatively high ¹³⁴Cs concentrations in fish reflects its tendency to remain in the water and its continued availability to biota. Both ⁶⁰and ¹³⁴Cs concentrations were high in the soft tissues. Co-60 was mainly distributed in the flesh, gut, gill, kidney, and liver, whereas¹³⁴Cs was mainly distributed in the flesh. The occurrence of relatively high ¹³⁴Cs concentrations in lake whitefish five years after their addition to the lake, long after ¹³⁴Cs concentrations are no longer detectable in lake water, attests to the continued persistence of this contaminant in aquatic biota.     

A dynamic model of N metabolism in the lactating dairy cow and an assessment of impact of N excretion on the environment

Improving N utilization in dairy cows and especially reducing N output in excreta is desirable due to global concerns of agricultural contribution of N to environmental pollution, particularly as ammonia. Data from five N balance experiments were used to develop a dynamic model that was evaluated with independent data. Model predictions of feces, urine, and milk outputs were close to observed values. Statistical analysis showed that 96% of mean square prediction error for feces and urine N output predictions was due to random variation. However, the model tends to overpredict milk N output, especially at higher N intake levels. Evaluation of model predictions for independent experimental observations from Agricultural Development Advisory Service at Bridgets (U.K.) showed good agreement between predicted and observed urine N output (95% due to random variation). However, there was a slight underprediction for fecal N output (14% mean square prediction error due to bias) and overprediction of milk N output (22% of mean square prediction error due to bias). The model predictions of N outputs in excreta were sensitive to changes in energy concentration of the diet. Dietary protein degradability had only a small influence on predicted fecal N output. However, the model was sensitive in its predictions of urine N when protein degradability was varied. Application of the model to assess reduction in ammonia emissions from dairy cows showed that increasing the energy concentration could potentially reduce ammonia emissions by up to 25% per cow. Similarly, reducing CP concentration in the diet to about 16% could reduce ammonia production by 20% and lower degradability of CP to match microbial requirement by 19% per cow. The model is a first step toward a mechanistic approach of nutrient modeling, and it is a valuable method for predicting N excretions and estimating N emissions from dairy systems.     

Evaluation of histopathologic and physiologic changes in cows having premature births after consuming Ponderosa pine needles

Premature calving, typified by early expulsion (17 to 43 days) of weak or dead calves and accompanied by retained placentas, was induced in 8 of 9 pregnant cows fed a mixture of Ponderosa pine needles and alfalfa hay. Five control cows of comparable gestation age fed only alfalfa hay maintained normal pregnancies until they were euthanatized at the time the pine needle-treated cows were producing premature calves. Serum specimens from all cows were assayed for progesterone concentration and ovaries and placentomes were examined for histopathologic changes. There were no bacterial, fungal, chlamydial, or viral agents determined to be associated with the premature births. Serum progesterone concentration in the treated cows decreased progressively and were 0.4 to 1.5 ng/ml at the time of premature calving. Histopathologic changes were evident in the placenta and corpora lutea of treated cows only. The number of binucleate trophoblastic giant cells in placentomes was less than normal and the number of necrotic luteal cells in corpora lutea was greater than normal.     

Technical note: A proposed method to determine the extent of degradation of a feed in the rumen from the degradation profile obtained with the in vitro gas production technique using feces as the inoculum

A method is proposed to determine the extent of degradation in the rumen involving a two-stage mathematical modeling process. In the first stage, a statistical model shifts (or maps) the gas accumulation profile obtained using a fecal inoculum to a ruminal gas profile. Then, a kinetic model determines the extent of degradation in the rumen from the shifted profile. The kinetic model is presented as a generalized mathematical function, allowing any one of a number of alternative equation forms to be selected. This method might allow the gas production technique to become an approach for determining extent of degradation in the rumen, decreasing the need for surgically modified animals while still maintaining the link with the animal. Further research is needed before the proposed methodology can be used as a standard method across a range of feeds.     

Monitoring distances travelled by horses using GPS tracking collars

Objective The aims of this work were to (1) develop a low-cost equine movement tracking collar based on readily available components, (2) conduct preliminary studies assessing the effects of both paddock size and internal fence design on the movements of domestic horses, with and without foals at foot, and (3) describe distances moved by mares and their foals. Additional monitoring of free-ranging feral horses was conducted to allow preliminary comparisons with the movement of confined domestic horses. Procedures A lightweight global positioning system (GPS) data logger modified from a personal/vehicle tracker and mounted on a collar was used to monitor the movement of domestic horses in a range of paddock sizes and internal fence designs for 6.5-day periods. Results In the paddocks used (0.8–16 ha), groups of domestic horses exhibited a logarithmic response in mean daily distance travelled as a function of increasing paddock size, tending asymptotically towards approximately 7.5 km/day. The distance moved by newborn foals was similar to their dams, with total distance travelled also dependent on paddock size. Without altering available paddock area, paddock design, with the exception of a spiral design, did not significantly affect mean daily distance travelled. Feral horses (17.9 km/day) travelled substantially greater mean daily distances than domestic horses (7.2 km/day in 16-ha paddock), even when allowing for larger paddock size. Conclusions Horses kept in stables or small yards and paddocks are quite sedentary in comparison with their feral relatives. For a given paddock area, most designs did not significantly affect mean daily distance travelled.