Stocking Method Research Articles

Herbage allowance and stocking method effect on grazing systems: Results of a long‐term experiment

AbstractSward management is critical for animal performance in pastoral environments. We evaluated the performance of sheep grazing Italian ryegrass pastures under factorial combinations of two stocking methods (SM) (continuous and rotational) and two herbage allowances (HA) (10% and 20% of LWT) over 9 years. Average daily gain (ADG) was greater in continuous than in rotational stocking (p < .001) and in HA‐20% when compared with HA‐10% (p = .002). Weight gain per hectare was greater in HA‐10% than HA‐20% (p < .001). HA and total herbage production were the most important factors determining live weight (LW) gain per hectare, whilst sheep ADG relies upon sward parameters (i.e., sward height). Moreover, to increase sheep LW production per hectare in grazing systems, the amount of herbage production and its availability to animals is more important than the SM. These outcomes provide the basis to build sound grazing systems through the optimization of sward management.

Data Sparseness and On‐Line Pretest Item Calibration‐Scaling Methods in CAT

The purpose of this study was to compare and evaluate three on‐line pretest item calibration‐scaling methods (the marginal maximum likelihood estimate with one expectation maximization [EM] cycle [OEM] method, the marginal maximum likelihood estimate with multiple EM cycles [MEM] method, and Stocking's Method B) in terms of itern parameter recovery when the item responses to the pretest items in the pool are sparse. Simulations of computerized adaptive tests were used to evaluate the results yielded by the three methods. The MEM method produced the smallest average total error in parameter estimation, and the OEM method yielded the largest total error.

A Comparative Study of On‐line Pretest Item—Calibration/Scaling Methods in Computerized Adaptive Testing

The purpose of this study was to compare and evaluate five on‐line pretest item‐calibration/scaling methods in computerized adaptive testing (CAT): marginal maximum likelihood estimate with one EM cycle (OEM), marginal maximum likelihood estimate with multiple EM cycles (MEM), Stocking's Method A, Stocking's Method B, and BILOG/Prior. The five methods were evaluated in terms of item‐parameter recovery, using three different sample sizes (300, 1000 and 3000). The MEM method appeared to be the best choice among these, because it produced the smallest parameter‐estimation errors for all sample size conditions. MEM and OEM are mathematically similar, although the OEM method produced larger errors. MEM also was preferable to OEM, unless the amount of time involved in iterative computation is a concern. Stocking's Method B also worked very well, but it required anchor items that either would increase test lengths or require larger sample sizes depending on test administration design. Until more appropriate ways of handling sparse data are devised, the BILOG/Prior method may not be a reasonable choice for small sample sizes. Stocking's Method A had the largest weighted total error, as well as a theoretical weakness (i.e., treating estimated ability as true ability); thus, there appeared to be little reason to use it.

Determinação do fator de cobertura do melão cultivado sob diferentes lâminas e salinidades da água de irrigação

Dois experimentos foram conduzidos com objetivo de se comparar metodologias de determinação do coeficiente de cobertura do solo pelo melão, quando submetido a condições diferenciadas de lâminas e nível de salinidade da água, em Mossoró, RN. O delineamento experimental adotado foi o de blocos ao acaso, no arranjo fatorial 2 x 2 x 6. Foram testados dois métodos (Stocking e régua), dois níveis de salinidade da água de irrigação (0,55 e 2,65 dS m-1) e seis lâminas (0,55, 0,70, 0,85, 1,00, 1,15 e 1,30 da ETm). Os métodos de medida do fator de cobertura do solo mostraram-se eficientes, detectando-se, em ambos, diferenças significativas entre os efeitos da qualidade da água e da lâmina de irrigação no desenvolvimento do melão. Os resultados obtidos pelo método da régua diferiram do método de Stocking apenas nas fases inicial e de crescimento do melão.

A modified calibration technique for the split film sensor

A split film sensor is preferred over an X-wire probe for the measurement of reverse flow fields. However, the prevailing calibration techniques for the split film sensor are reliable for small pitch angles only. In this study, Stock's method for pitch angle response is improved to provide a more reliable calibration for a wide range of velocity magnitude and pitch angle. To show its usefulness, the proposed method is applied to a turbulent reattaching flow behind a rearward-facing step. The measured data compare favourably with those measured using conventional hot-wire anemometry.

Motility assay of human sperm by photon correlation spectroscopy.

Microscopic methods of performing motility assays of spermatozoa are slow, subjective, and involve a small number of spermatozoa. Laser light-scattering methods can analyze the motility of many spermatozoa within minutes. The swimming speed distribution of human spermatozoa was investigated by photon correlation spectroscopy. The sperm was diluted in seminal plasma to avoid modifying the viscosity. The swimming speed distribution was reconstructed from the correlation data by Stock's method of splines. When compared with a videomicroscopic assay, the reconstructed swimming speed distribution accurately reflects translational motion between 0 and 80 micrometers per second, while for speeds greater than 80 micrometers per second the distribution is distorted by the effects of rotational motion.