Anti-nutritive factors in animal feedstuffs and their effects on livestock.

This review deals with compounds -mainly organic-which when present in the diet, may affect the health of livestock or interfere with normal feed utilization. The anti-nutrients occur as natural constituents of plants and animal feeds, as artificial factors added during processing, or as contaminants of the ecosystem. Their mode of action, metabolism in the living body, and detoxification mechanisms, are described briefly.

Effect of proline on arginine uptake and nitrogen metabolism of lactating goats.

The hypothesis that addition of proline may save dietary protein for milk production was tested by administration of proline to two goats through a duodenal cannula. Because proline is synthesized by the mammary gland in vitro from arginine, the effect of proline supplementation on arginine uptake by the gland was tested in vivo. Arginine uptake, calculated from arterio-venous difference, dropped significantly in both animals, especially in the morning 1 h after milking, when a low-protein diet was fed.

Apparent amino acid absorption from feather meal by chicks.

The apparent absorption values of individual amino acids from two samples of feather meal (FM) were determined in the lower ileum of chicks fed on diets containing magnesium ferrite as a marker. The average absorption values for FM amino acids were low, approximately 0.50, as compared with approximately 0.

Nutritional value of feather-meal protein for chicks.

Ileal absorption of nitrogen was determined for feather meal (FM) samples, using magnesium ferrite as a marker. Diets containing 15% FM were balanced by linear programming, using two nitrogen absorption values for FM: 55%, as found, or 85%, an average value for standard feeds. When nitrogen absorption of FM was calculated as 55%, the growth of chicks from one to three weeks of age was similar to that of the control chicks.

Colorimetric determination of uric acid in poultry excreta and in mixed feeds.

Uric acid was determined in samples of poultry excreta and animal feeds to which poultry excreta were added. The rapid colorimetric method used by Van Handel was adapted for this purpose. The method is simple, accurate, and gives reproducible results.