Some factors affecting egg weight in domestic fowls

PART I. FACTORS AFFECTING EGG WEIGHT IN THE DOMESTIC FOWL.S.C. White Leghorn and White Wyandotte pullets housed behind ordinary glass and not given adequate amounts of vitamin D gave significantly lower average egg weights than comparable pens given adequate quantities of the anti-rachitic vitamin. The egg size was not significantly less in the irradiated ergosterol pen than it was in the cod liver oil pen. There was no significant difference in the egg weights for lighted and unlighted pens of Single Comb White Leghorn pullets. An all-in-one ration in pellet form gave significantly larger egg size than the same ration in mash form for both pullets and yearlings of the White Leghorn breed. Under the conditions of the experiment, both green food and oyster shell proved of value in increasing egg size when supplementing "All in one" rations. Fish meal proved definitely of greater value for egg size than decorticated extracted earth nut meal (peanut meal) and was slightly more valuable than extracted soya bean meal or meat meal. A mineral supplement did not materially increase the egg size when used with a meat meal ration, unlimited oyster shell being available. When a standard ration was fed to Cuckoo Leghorn Rhode Island Red cross pullets, egg size was not materially affected by the feeding of extra quantities of dried skim milk. When two rations of similar constitution and mineral analysis, but varying in protein content, were compared, there was no significant difference in egg size. There were no significant differences in egg size for either pullets or yearling Leghorns when fish meal replaced meat and bone meal, dried butter milk replaced dried skim milk, or decorticated earth nut meal (peanut meal) replaced extracted soya bean meal in a mixed protein ration. A mixed protein ration did not give a larger egg size than a simple protein ration. There were indications in several of the experiments that about April or May there is a turning point in an egg weight cycle. Further research is required to determine the relation of the protein and mineral content of the ration to the size of the eggs produced. It has not been possible to confirm previous work that proteins or minerals are of special value in regard to egg weight.PART II SEX LINKAGE IN THE DOMESTIC FOWL,PART III. A LEG COLOUR CHIMERA. A POSSIBT,F CASE OF SOMATIC MUTATION IN THE DOMESTIC FOWL.PART IV. A CASE OF POSSIBLE NON -DISJUNCTION IN THE DO /0STIC FOWL.PART V. THE INHERITANCE OF THE RE FACTOR IN THE RABBIT

Being, being human, becoming beyond human

The London-based New Scientist Magazine has been publishing popular science and technology news since 1956. Each year it holds a large four-day conference in London, called ‘New Scientist Live,’ hosting talks and exhibitions from many of Europe’s leading innovators and scientists, and attracting tens of thousands of visitors. The exhibition and speaker’s space is divided into five main stage areas: Cosmos, Earth, Humans, Technology, and Engineering. While these categories have always overlapped to varying degrees, their distinctions are increasingly becoming blurred. This imbrication of the body and manufactured forms invites new biosocial approaches to investigating the role of materials within the sociality of the body. The body has, to varying degrees, always been manipulated and ‘made’

Letter from Emilie T. Y. Parkhurst to [Jeanne C. Carr], 1891 Dec 5.

[letterhead]San Francisco, Dec. 5 1891Dearest of friends:Can you not write for us a biographical sketch of John Muir such as you outlined when I was visiting you: — one taken from his letters largely? I would like to publish it before the Century publishers the one by my father if possible. I have written to the Cosmopolitan and they promise an early appearance of your article : but that may mean some months yet. If we could afford the fifty dollars I would withdraw it from there & publish it in ours : but we cannot just yet. We can pay you about $25 for the Muir article. Will you do it? I am so grieved to learn that you have been ill, but trust that you are better again. Did you ever mail me the Doctor’s book? I never received it : but as you06390 wrote saying it would be sent by the same mail, I felt afraid of its possible miscarriage. I will have a copy of the Holiday magazine to send you in a few days. Have the winter excursionists begun to pour in yet? Take good care of yourself and God bless you.Lovingly your friendEmelie T. Y. Parkhurst.MRS. E. T. Y. PARKHURST.ASSISTANT EDITORCalifornian Illustrated Magazine.San Francisco, Cal

USING NONLINEAR GROWTH CURVES TO ESTIMATE HEAT STRESS IN PROCESSING FEEDLOT CATTLE

Summertime heat waves cause excessive discomfort and, in extreme cases, death of feedlot cattle. During such emergencies, extension specialists are called upon for recommendations of management practices to minimize heat stress. Since moving cattle is believed to raise body temperature 1 degree, one recommendation is to move cattle before mid-day or reschedule to another day. More knowledge of body temperature dynamics could lead to more specific recommendations of how far cattle can be moved without stress. Several models are investigated - especially those involving exponential growth(challenge) and decay (recovery) such as the bi-exponential, single compartment and other models in pharmacokinetics. Data from feedlot trials can be messy and judgement calls involving starting and ending times, model parametrization, and statistical assumptions can influence the results. Analyzes from SAS: proc NLIN and checks on nonlinear assumptions are discussed

USING THE BI-LOGISTIC MODEL TO ESTIMATE BODY TEMPERATURE IN FEEDLOT CATTLE

Processing and handling cattle require an expenditure of energy causing an elevation of body temperature, depending on the ambient conditions. More knowledge of body temperature, Tb, dynamics could lead to more specific recommendations of how far cattle can be moved without stress. The bi-Iogistic model has been used to describe the handling process. This model estimates several important biological parameters: rate of increase in Tb (rate of heat challenge), the maximum Tb (max Tb), time to reach maximum Tb (tmax) and recovery rate (rate of decrease in Tb). The objectives of this study are: to compare parameter estimates from the bi-Iogistic model with a segmented version of the model; to investigate the robustness of the model for different definitions of recovery; and, to check for hormetic behavior using switching functions

COMPARING EXPERIMENTAL DESIGNS FOR A BI-LOGISTICAL MODEL USED TO ESTIMATE HEAT STRESS WHEN MOVING FEEDLOT CATTLE

Processing and handling cattle requires expenditure of energy causing an elevation of body temperature, depending on the ambient conditions. Therefore, caution should be exercised in moving cattle, especially during summer. More knowledge of the dynamics of body temperature, (Tb), could lead to specific recommendations on how far and under what conditions cattle can be moved before becoming thermally challenged. Data comes from feedlot trials conducted over four days. A bi-logistic mixed model of Tb is used to describe the effects of moving and handling on Tb. This model provides estimates for several important biological parameters describing the thermal challenge and recovery: the maximum Tb challenge, challenge rate constant (rate constant for increase in Tb), time to maximum rate of challenge (challenge inflection point), baseline for recovery, recovery rate constant (rate constant for decrease in Tb) and time to maximum recovery rate (recovery inflection point). Fitting a nonlinear mixed model with six parameters under extremely variable animal and environmental conditions is difficult especially when the treatment factor (distance) is introduced into the model. Additional difficulties in fitting the model arise as the experimental design increases in complexity from a CRD to a replicated Latin square. The objectives of this study are: to examine the bi-logistic model with distance as a treatment factor and estimate the relative efficiencies as the experimental design is simplified

LOGISTIC REGRESSION ANALYSIS TO DETERMINE FACTORS CONTRIBUTING TO SUMMER FEEDLOT DEATHS

Summer heat has already been identified as a major factor for cattle deaths in the feedlot. This study attempts to assess what other factors contribute to and/or influence cattle deaths. Identifying multiple factors that contribute to summer feedlot deaths could aid feedlot managers in implementation of mitigation strategies and minimize the loss of nearly finished cattle. Daily pen, cattle, and nutritional characteristics were recorded and included in this generalized linear mixed model analysis. Cattle data were obtained from cattle pens at a single location from July 1, 2010 to July 31, 2010. Hourly weather data were acquired from this feed yard while solar radiation was received from a neighboring town. Rather than using multiple weather variables, a single comprehensive climate index that summarizes several weather variables is used to capture the apparent feel of the weather. After reviewing the data, a statistical model is developed and odds ratios are computed for statistical inference. According to these odds ratios, cattle fed on severe west slopes had significantly higher odds of death than other types of slopes. Analysis of feed intake indicates pens consuming 16 pounds of feed per head or less during July 16 – 18 have higher odds of death than other consumption levels

COMPARISON OF SAS PROC NLIN AND NLMIXED FOR PARAMETER ESTIMATION IN PET MODEL

Cattle body temperatures were measured under semi-controlled hot cyclic chamber temperatures. The four-parameter nonlinear PET model, is used to estimate body temperature in cattle challenged by heat stress. For each steer, the parameters can be estimated by the Nlin procedure and the sensitivity of each animal can be studied. It is also desirable to generalize the results by using the Nlmixed procedure to combine both the fixed and random effects. When comparing the results from the two procedures, we found heterogeneity among animals and/or days caused convergence problems for proc Nlmixed. Simulation studies were used to study how deviations from homogeneity effected the accuracy of parameter estimates, coverage of confidence intervals, and measures of nonlinear behavior when using the PET model to describe the dynamics of heat stress in cattle

COMPARATIVE STUDY OF TIME SERIES AND MULTIPLE REGRESSION FOR MODELING DEPENDENCE OF CATTLE BODY TEMPERATURE ON ENVIRONMENTAL VARIABLES DURING HEAT STRESS

During the summer, a challenging thermal environment is known to cause a significant reduction in food intake, growth, milk production, reproduction and even death in cattle. In this study, we attempt to characterize the relationship of cattle body temperature with several environmental variables, such as air temperature, soil surface temperature, relative humidity, solar radiation, wind speed, incoming and outgoing short and long wave radiation. For these variables, the measurements taken over time are correlated. This places severe restrictions on the applicability of many conventional statistical methods that depend on the assumption of independent and identically distributed errors. In addition to these assumptions, there is serious collinearity among several weather variables and the variables are not stationary. Commonly used multiple regression models can be misleading when predictor variables are stochastic and issues of collinearity and non-stationary are ignored. In this paper, time series analysis is used as a tool to investigate the adequacy of classical regression models. Various aspects of dynamics of cattle body temperature and its relationship to environmental variables are discussed using the frequency and time domain analysis. Finally, we present a detailed approach for fitting cattle body temperature using a transfer function model with multiple environmental variables as inputs

COMPARING FUNCTIONAL DATA ANALYSIS AND HYSTERESIS LOOPS WHEN TESTING TREATMENTS FOR REDUCING HEAT STRESS IN DAIRY COWS

Various techniques are commonly used to reduce heat stress, including sprayers and misters, shading, and changes in feed. Oftentimes studies are performed where researchers do not control the times when animals use shading or other means available to reduce heat stress, making it hard to test differences between treatments. Two methods are used on data from a study where Holstein cows were given free access to weight activated “cow showers.” Functional data analysis can be used to model body temperature as a function of time and environmental variables such as the Heat Load Index. Differences between treatment groups can be tested using a Functional Bayesian MCMC model. Alternatively hysteresis loops, such as the ellipse, formed by a plot of air temperature or the Heat Load Index against body temperature over the course of a day can be estimated and their parameters used to test differences between cows with access to showers and cows without. Results from an R package hysteresis, which can estimate these loops and their parameters are illustrated. Functional data analysis allows for looser assumptions regarding the body temperature curve and the ability to look for differences between groups at specific time points, while hysteresis loops give the ability to look at heat stress over the course of a day holistically in terms of parameters such as amplitude, lag, internal heat load and central values