Full Growth Period Research Articles

Automated Weighing of Group-housed, Growing-finishing Swine

A system for automated acquisition of the mean pig weight from a group of growing-finishing animals was developed and tested. Each time an animal entered a crate to obtain a drink of water, a time series of weights was recorded. A state machine representation was implemented to capture weight events and to put time series weight recordings into a queue. Three algorithms (mean, histogram, and median) were devised and evaluated to extract animal weight from the time series recording. Four tests were performed—short-term tests included test 1 with 12 animals of 64.5 to 96.4 kg initial weight; test 2 with 8 animals of 70.9 to 75 kg; test 3 with 3 individual animals of 45, 68, and 93 kg; and test 4 was for a full growth period with 10 animals. The first three experiments were used to develop and refine the system, and test 4 was used to assess the long-term performance and feasibility. Comparisons between estimated weight and “spot checks” with a mechanical scale were typically within about ±1% over test 4. The histogram algorithm was found to be the best for estimating average weight. Accuracy was not affected by variation in animal weight (tests 1 and 2); however, different length data windows affected accuracy and a 4-h window was best. A time series queue of at most 150 s of data was found to be adequate and the histogram algorithm was successful with as few as 10 data points. Locating the sole water supply within the weigh crate did not affect growth rate compared to a control group. A change rate (CR) index was devised to compare daily activity and to flag pen health problems

Dimensional weights and forage of Barclay willow and sweetgale on moose ranges in the wetlands of the Copper River Delta, Alaska

Above-ground shoots of Barclay willow ( Salix barclayi) and sweetgale ( Myrica gale var. tomentosa) from shrub-swamp on the wetlands of the Copper River Delta, Alaska, were harvested at the early-growth, full-growth, and early-dormancy stages of growth. Seven dimensional measurements (vertical height, basal stem diameter, upper stem diameter, basal stem length, crown depth, maximum crown diameter, second crown diameter) were made on each above-ground shoot before harvest. The cross-sectional area of the crown was calculated from crown diameters and also used as a non-destructive measurement. Each shoot was sorted into four individual (basal stem, branch, terminal twig, leaf) and two combined (crown wood, total above-ground) dimensional weight categories and the oven-dry weights of each category determined. Measurements were used as independent variables in forward, stepwise multiple regression to develop a ‘best model’ estimator of mean dimensional weight at each growth stage. The ability of the regression models to accurately predict mean dimensional weight at each growth stage was tested on an independent sample of above-ground shoots of both shrubs. The early-dormancy regression model predicted mean weights of basal stem, twig and total above-ground dimensional weights of Barclay willow within 1% of actual weights. The full-growth regression model gave the most accurate predictions of the mean dimensional weights of crown wood, branch and leaf of Barclay willow. The early-dormancy regression model provided the closest estimates of the mean weights of basal stem and crown wood of sweetgale. Total above-ground shoot and branch mean weights were best estimated by the regression model for the full-growth period. Neither regression model gave accurate estimates of the mean weights of sweetgale twigs and leaves. Digestibility, nutrient status and energy content of the material in each dimensional category were determined at each growth period.

Diagnostic nitrogen concentrations for cabbages grown in sand culture

The cabbage cv. Rampo was grown in sand culture with 5 nitrogen (N) levels, between 2 and 43 mmol/L, applied as nitrate each day in a complete nutrient solution. The youngest fully opened leaf (YFOL), which became the wrapper leaf at heading, the youngest fully expanded leaf (YFEL) and the oldest green leaf (OL) were harvested at a minimum of 2-week intervals over a 12-week growth period. Standard laboratory leaf total N and nitrate-N determinations and rapid petiole sap nitrate-N determinations were conducted on YFOL, YFEL and OL. Total N was also determined in bulked leaves. The relationship between growth rate relative to the maximum at each sampling time and leaf N concentration was used to derive diagnostic petiole sap nitrate-N, leaf nitrate-N and total N in YFOL, YFEL and OL and bulked leaf total N concentrations. Critical concentration corresponded to 90% maximum growth rate and adequate concentration corresponded to 9 1-1 00% maximum growth rate. Petiole sap nitrate-N concentration, which can be measured rapidly in the field, and leaf nitrate-N concentration were very responsive to N application where positive growth responses were recorded. Critical N concentrations are presented for all leaves at most sampling times throughout the growth period. Critical total N concentrations in YFOL, YFEL and bulked leaves were higher during the pre-heading growth stage (weeks 2-6) than the post-heading growth stage (weeks 8-12). Critical N concentrations were inconsistent over the growth period and it was not possible to present single values to represent the full growth period, with 2 exceptions. A critical petiole sap nitrate-N concentration for OL of 3.0 g/L can be recommended for the full growth period because it represents a percentage of maximum growth rate range of 88-95%. Similarly, for YFEL, a critical total N concentration of 4.10% pre-heading (range 4.10-4.38%) represents a percentage maximum growth rate range of 62-90% and a post-heading critical total N concentration of 3.10% (range 3.10-3.50%) represents a percentage maximum growth rate range of 76-90%. The concentrations of potassium, phosphorus, calcium, magnesium and sulfur in YFOL, YFEL, OL and bulked leaf corresponding to N treatments producing maximum growth rates are also presented.

A Study on Frost Formation : The Process of Frost Formation involving the Phenomena of Water Permeation and Freezing

The formation process consists of three periods : crystal growth frost layer growth and frost layer full growth period. This paper studies the process in the layer full growth period, which is characterized by the phenomena of water permeation and freezing in the layer. It was shown experimentally that this process could be classified largely into two formation patterns, depending on the diffusion rate of water vapour. The position of the freezing interface in the layer was related to the water quantity held on the surface by surface tension and the heat flux in layer. Further, the structure in this period was composed of a freezing layer and a porous layer, and the properties could be estimated from this structure.