The effects of treatment of barley grain with sodium hydroxide and milling on its nutritive value for finishing pigs

Abstract

ABSTRACTGrowing pigs were given diets based on barley (whole or milled), which was either untreated or sprayed with an aqueous solution of sodium hydroxide (270 g sodium hydroxide per kg water) to give 33·8 g sodium hydroxide per kg dry matter. The barley grain was treated with sodium hydroxide while in the whole state. A total of 48 pigs penned individually were given the diets on a restricted scale of feeding from an initial weight of 31·6 kg until slaughter at 81·7 kg live weight. In a metabolism study, eight boars were subjected to the same experimental treatments in two identical 4 × 4 balanced change-over experiments.The diet containing untreated milled barley gave significantly faster live-weight gain and lower food conversion ratio than the other three diets (P < 0·001). Food conversion ratios were similar for untreated whole barley and sodium hydroxide-treated barley, whether this was whole or milled. Killingout proportion was similar for untreated and treated milled barley but was significantly lower when the diet contained untreated or treated whole barley.Milling significantly increased the digestibility of energy and nitrogen. Treatment with sodium hydroxide improved the digestibility of energy in the diet with whole barley but not in the diet with milled barley. With both whole and milled barley, treatment with sodium hydroxide increased the digestibility of crude fibre (P < 0·05) but with ground barley the digestibility and retention of nitrogen were reduced considerably by treatment with sodium hydroxide.It is concluded that treatment of barley with sodium hydroxide did not improve the nutritive value of either milled or whole grain, that it reduced the digestibility of nitrogen and that it severely depressed the utilization of digested energy for growth.