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Poultry Excreta Containing Polychlorinated Biphenyls as a Protein Supplement for Lactating Cows

Agricultural Environmental Quality Institute¹
Agricultural Environmental Quality Institute¹
Animal Physiology and Genetics Institute² Agricultural Research Center, USDA Beltsville, MD 20705

ABSTRACT

A conventional concentrate mixture and one containing dehydrated poultry excreta (32%) were fed to two groups of 12 cows each to provide 36% of total dietary nitrogen and 15% of total dry matter intake for 90 days. The digestibilities determined with wethers for the two diets were not different. Averages were: organic matter, 81%; cell walls, 57%; and nitrogen, 73%. Both concentrate mixtures were pelleted and fed to cows according to maintenance and milk production requirements not provided by forages. Cows fed the concentrate containing poultry excreta consumed 17% less corn silage and 5% less concentrate dry matter and produced 10% less milk. Ratios of dry matter intake from feed to fluid milk (.82) were equal for the two groups of cows. Milk production declined at the same rate for the two groups of cows. Poultry excreta used in diets for 6 of 12 cows and fed for 50 days was from hens fed diets containing 20 ppm of polychlorinated biphenyl mixtures containing 21 to 68% chlorine. For the other 40 days, all 12 cows were fed uncontaminated poultry excreta. Monochlorobiphenyls to tetrachlorobiphenyls were not detected in milk, but pentachlorobiphenyls to deca-chlorobiphenyls were detected. With intakes normalized to 1 ppm in the concentrate, total residue in milk fat at 35 days was <.5 ppm for 21, 32, and 42% chlorine and 1.2, 2.9, and 4.1 ppm for 48, 54, and 68% chlorine. Fifty days after the last feeding, residues dropped to .5, 1.2, and .7 ppm for the 48, 54, and 68% biphenyls. In spite of reduced milk output, the economics of feeding dehydrated poultry excreta compare favorably with those of conventional crude protein.