Introduction.- Vector and Matrix Algebra.- The Multivariate Normal Distribution, Multivariate Normality, and Covariance Structure.- One- and Two-Sample Tests.- Multivariate Analysis of Variance.- Discriminant Analysis.- Canonical Correlation.- Principal Component Analysis.- Factor Analysis.- Structural Equations.

Applied Multivariate Analysis

We present the results of an experiment designed to examine the role pred- ator-avoidance behaviors play in structuring a community. Previous studies have shown that small bluegills (Lepomis macrochirus) shift their habitat use in the presence of their predator, the largemouth bass (Micropterus salmoides). The addition of bass causes small bluegills to make greater use of structured (vegetated) habitats and reduces their use of open (limnetic) habitats. We hypothesized that these effects of bass on bluegill behaviors should lead to an increase in the abundance and mean size of zooplankton when bass are present. We tested this prediction in two ponds by stocking small bluegills with and without bass. Pronounced differences in zooplankton abundance and size structure developed be- tween treatments, with three cladocerans (Daphnia, Diaphanosoma, and Ceriodaphnia), and the phantom midge Chaoborus, becoming more abundant with bass. These effects of bass were not due to changes in bluegill abundance, as very few bluegills were eaten by the bass, and bluegill densities did not differ between treatments. Calculation of bluegill feeding rates shows that the fish exerted substantial mortality on the zooplankton and that cladocerans experienced lower per capita death rates (due to bluegill) in the presence of bass. We discuss these results in light of current theory predicting how foragers should deplete prey among habitats that differ in mortality risk.

Predator Avoidance and Community Structure: Interactions among Piscivores, Planktivores, and Plankton

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.1981.tb00595.x

A Critical Review of Methods for Evaluation of Spermatogenesis from Seminal Characteristics

The hypothesis was tested that greater growth of the dominant follicle of wave 1 (first follicular wave of an interovulatory interval), compared with that of subsequent anovulatory waves, is due to lower circulating concentrations of progesterone during the growing phase of the follicle. Control heifers (n = 6) were compared with heifers (n = 6) treated with a decreasing dose of progesterone from day 0 to day 5 (ovulation = day 0). Maximum diameter (12.7 +/- 0.9 versus 15.3 +/- 0.7 mm) and mean diameter of the dominant follicle of wave 1, averaged over days, were smaller (P 20 mm) follicle was associated with delayed emergence of wave 2. The hypothesis was supported. Results also showed that the high dose of progesterone suppressed the dominant follicle more than the physiological dose when given during the growing phase, but not when given after the growing phase.(ABSTRACT TRUNCATED AT 400 WORDS)

/pdf/effect-of-progesterone-on-ovarian-follicles-emergence-of-111taki1q4.pdf

Effect of progesterone on ovarian follicles, emergence of follicular waves and circulating follicle-stimulating hormone in heifers.

The effect of rumen liquid volume, pH and concentration of volatile fatty acids (VFA) on the rates of absorption of acetic, propionic and butyric acids from the rumen was examined in lactating dairy cows. Experimental solutions introduced into the emptied, washed rumen comprised two different volumes (10 or 30 l), four levels of pH (4.5, 5.4, 6.3, 7.2) and three levels of individual VFA concentrations (20, 50 or 100 mM-acetic, propionic or butyric acid). All solutions contained a total of 170 mM-VFA and an osmotic value of 400 mOsmol/l. Absorption rates were calculated from the disappearance of VFA from the rumen corrected for passage with liquid phase to the omasum. An increase in initial fluid pH caused a reduction in fractional absorption rates of propionic and butyric acids. Increasing the initial pH from 4.5 to 7.2 reduced fractional absorption rates of acetic, propionic and butyric acids from 0.35, 0.67 and 0.85 to 0.21, 0.35 and 0.28/h respectively. The fractional absorption rates of all VFA were reduced (P < 0.05) by an increase in initial rumen volume. The fractional absorption rate of acetic acid was lower (P < 0.05) at an initial concentration of 20 mM than of 50 mM. The fractional absorption rate of propionic acid tended (P < 0.10) to decrease as the level of concentration increased while fractional absorption rate of butyric acid was not affected by butyric acid concentration. These results indicate that relative concentrations of VFA in rumen fluid might not represent relative production rates and that attempts to estimate individual VFA production from substrate digestion must take account of pH and VFA concentration.

/pdf/absorption-of-volatile-fatty-acids-from-the-rumen-of-ysw18ji4gp.pdf

Absorption of volatile fatty acids from the rumen of lactating dairy cows as influenced by volatile fatty acid concentration, pH and rumen liquid volume

Analysis of repeated measurements of animals.

Animal scientists who conduct experiments involving repeated measurements of animals often are frustrated by low statistical power of tests for comparisons of treatment means. In many cases, low power of the traditional tests simply is the consequence of low replication (few animals per treatment) that was forced by cost or complexity of experimental technique. A method is given for comparing treatments in a way that permits sensitive tests (via partition of the treatment X period interaction), often when the number of animals per treatment is not more than five or six. Modifications for the procedure are given for the case of heterogeneous variances and covariances. An example from mammary physiology is used to illustrate the procedure and to compare it with standard methods of analysis.

J. L. Gill

Papers

Analysis of repeated measurements of animals.

Repeated measurement: sensitive tests for experiments with few animals.

Balanced Two-Period Changeover Designs for Several Treatments

Combined significance of non-independent tests for repeated measurements.