The early weaning of pigs VII. The effect of level and source of protein in the diet of pigs weaned at 10 lb. live weight on subsequent performance and carcass quality

Abstract

1. Dry-meal diets based on whitefish meal or soyabean oil meal, balanced in respect of minerals, and containing 28, 23 or 18% crude protein were given to pigs from 10 to 25 lb., and similar diets containing 18% crude protein were given from 25 to 40 lb. From 40 to 100 lb. and from 100 lb. to bacon weight all pigs were given the same diets with 16% crude protein and 14% crude protein, respectively.2. From 10 to 25 lb. live weight the results showed that:(a) With diets based on whitefish meal there was an improvement in growth rate of 11% (P < 0·05) and an improvement in feed conversion efficiency of 14% (P < 0·001) when the level of crude protein was increased from 18% to 23%. Growth rate and feed conversion efficiency were not improved further by increasing the level of crude protein from 23 to 28%.(b) With diets based on soyabean oil meal, feed conversion efficiency and growth rate were not improved by increasing the protein in the diet from 18 to 23%, and performance was similar to that on the 18% protein diet based on whitefish meal. Pigs fed on the soyabean diet containing 28% protein were unthrifty and grew very slowly; some showed gastric ulceration.(c) Consumption of the diets containing 18% crude protein was 8% higher (P < 0·05) than consumption of the other diets.(d) Apparent digestibility of the dry matter of the diets, as measured by the chromic oxide marker method, rose as the pigs grew older, and apparent digestibility of the dry matter and crude protein of the diets based on soyabean oil meal was consistently lower than when whitefish meal was the main supplementary source of protein.