Content and retention of sulphur in wool as affected by formaldehyde treatment of the diet, level of energy intake, and intraperitoneal supplementation with DL-methionine

Abstract

Young Romney sheep were fed indoors in pens in three experiments. Untreated and formaldehyde (HCHO)-treated casein were fed as supplements to a maintenance ration of hay (Experiment 1); untreated hay and two hays treated with HCHO were fed at maintenance and half maintenance levels of energy intake, with and without intraperitoneal supplementation with dl-methionine (Experiment 2); and untreated and HCHO-treated silage were fed ad libitum with and without intraperitoneal supplementation with dl-methionine (Experiment 3). The amount of sulphur retained in wool was increased by HCHO treatment of casein, by increasing the level of casein intake, and by the administration of DL-methionine, due to increases in both the sulphur content and the growth rate of wool. Formaldehyde treatment of hay had no effect on either the sulphur content or the amount of sulphur retained in wool. Increasing the level of hay intake and HCHO treatment of silage (which caused an increase in silage intake) both increased wool sulphur retention, due only to increases in wool growth rate. The proportion of methionine-sulphur recovered in wool was respectively 35% and 45% on the hay and silage diets. This is discussed in relation to the overall efficiency of conversion of absorbed amino acids to wool. It is considered that the failure of HCHO treatment of hay to increase sulphur retention in wool casts doubt on whether the treatment, in this instance, increased the amount of sulphur-containing amino acids available to the sheep.