Dried poultry manure as a source of phosphorus for sheep

Abstract

SummaryFeeding and balance trials with32P were carried out to measure the true absorption of P in battery and broiler waste and to assess the risk of urolithiasis in sheep.Groups of six, 8-week-old Scottish Blackface lambs were given one of eight experimental diets containing barley and either 15, 30, 45 or 60% of dried broiler or battery waste. After about 12 weeks on the diet, balance trials with32P were conducted on a sample of the female lambs from each dietary group. The phosphorus intakes ranged from 4·6 to 15·9g/day.Poultry waste was a good source of P. The proportion of dietary P absorbed by the lambs (A) ranged from 0·49 to 0·90 and was inversely related to the dietary intake of P (I). The relationship was A = 0·893 – 0·0219I. All lambs were in positive P balance (0·24–2·81 g/day), but only the bones from the lambs consuming the diets containing 45 and 60% broiler waste were not osteoporotic.All lambs absorbed more P than they retained and the partition of the excess between urine and faeces were very variable.No clinical cases of urolithiasis were seen, but uroliths were found at post-mortem. The incidence was highest in lambs consuming broiler waste and in lambs consuming the diets containing 15% poultry waste.