ALKALI TREATMENT OF SOYBEAN PROTEIN CONCENTRATE IN MILK REPLACERS: ITS EFFECTS ON DIGESTION, NITROGEN RETENTION, AND GROWTH OF LAMBS

Abstract

Alkali treatment to disperse a soybean protein concentrate (SPC) was studied in two milk replacer experiments, in which the SPC supplied 50% of the total nitrogen. In experiment 1, six lambs were used in a double 3 × 3 latin square digestion and nitrogen balance trial. The three treatments of the SPC in the milk replacer were: control (no alkali), alkali 1 (0.05 N NaOH at 40 C, neutralized with HCl after 15 min), and alkali 2 (same as 1, but neutralized after 18 hr at 5 C). The remainder of the diet ingredients were homogenized with a Polytron. Alkali treatment increased digestibility of dry matter (91, 93, and 95%, P < 0.01, on the three treatments, respectively), nitrogen, and energy, but tended to reduce the percent of absorbed nitrogen that was retained (63, 61, and 60%, P < 0.20). The control (complete diet prepared with the Polytron) and alkali 1 treatments were compared in a growth and metabolism trial in experiment 2. Growth of a total of 19 lambs from about 4 days to weaning from milk replacer at 26 days of age tended to be lower on the alkali-treated than the control SPC milk replacer (179 vs. 215 g/day, P < 0.20); however, growth to 10 weeks of age was similar for both groups and averaged 250 g/day.