Value of lucerne juice and grass juice as sources of protein for the growing pig

Abstract

Six experiments, involving a total of 282 individually-fed pigs, were completed in which the value of lucerne juice, and in one experiment of grass juice, as a source of protein for the growing pig was determined. The juices were products of a green crop fractionation process. The juice was preserved in three ways and was stored for feeding over several weeks. Pigs weighing up to 54 kg received sufficient juice to replace either all or half of the protein provided by the 7% white-fish meal included in an all-meal control diet. From 54 kg to 90 kg liveweight, juice replaced all of the protein supplied by the 3.5% white-fish meal included in the all-meal diet. In carrying out the replacement, all nutrients in the juice other than protein were ignored. When the juice was given according to its true protein content, as determined every 14 days, and was used to replace 3.5% white-fish meal protein throughout the growing period from 20 to 90 kg liveweight, performance and carcass quality were closely comparable to those of control pigs fed on meal only, and the consumption of white-fish meal was reduced by 70%. When the juice replaced 7% white-fish meal protein, the results were poorer than those of the all-meal control pigs. Satisfactory results were also obtained when the juice was given in conjunction with liquid cheese whey (replacing, on a dry matter basis, 30% of the barley meal in the all-meal control diet). Propionic acid (1%) was ineffective as a preservative of the juice. The addition of 1.4 g/l of sodium metabisulphite together with acidification with HCl to pH 3 significantly reduced the rate of loss of true protein during storage of the juice; if, in addition, the juice was heated to 85°C for a few seconds, loss of true protein over a period of many weeks was negligible.