The nutritive value of liquid whey, either sour or sweet, when given in restricted amounts to the growing pig

Abstract

Three experiments were completed in which liquid cheese whey, either sour or sweet (preserved with 0.1% formalin), was fed in restricted amounts as a partial replacement of the barley meal component of growing pig diets from 20 to 90 kg liveweight. All diets were compounded so as to provide comparable daily intakes of total protein, major minerals and vitamins and included a high-copper supplement. The performance and carcass quality of pigs fed whey in amounts to replace, on a DM basis, 30% of barley meal were closely comparable to those of all-meal fed control pigs. There were no differences of significance between pigs fed sour or sweet whey (mean titratable acidity 2.2 and 0.27, respectively), nor between pigs receiving white-fish meal or soyabean meal as the sole protein supplement in the basal meal fed with the whey. At this level of intake, it was calculated that 1.3 l whey have the same nutritive value as a source of protein and energy as 0.1 kg of barley meal (88% DM). (1 gal. whey is equivalent to 3 4 lb barley meal.) When the amount of sour whey fed replaced 50% of barley meal, there was a significant adverse effect on the performance of the pigs. Feeding with whey increased the amounts of copper found in the kidney and liver at slaughter but these did not approach toxic levels; the extent of the increase appeared to be positively correlated with the quantity and acidity of the whey. Copper stores in these two organs were reduced when soyabean meal replaced white-fish meal as the protein supplement.