LOW-GLUCOSINOLATE, LOW-ERUCIC ACID FULL-FAT RAPESEED (CV. TOWER) AS A PROTEIN AND ENERGY SOURCE IN LAMB MILK REPLACERS

Abstract

Dehulled, low-erucic acid–low-glucosinolate, full-fat rapeseed (FFRS), was studied as a protein source in milk replacers for lambs. Before being incorporated into the milk replacers to provide 25% (FFRS-25) or 50% (FFRS-50) of the total dietary protein, the FFRS was either passed through a colloid mill (milled) or left unmilled. When compared with an all-milk protein diet (FFRS-0), inclusion of the unmilled FFRS decreased the digestibilities of dry matter, nitrogen and energy (P < 0.01). Addition of unmilled FFRS to the milk replacer also decreased N retention (P < 0.01), but did not affect average daily gain. Addition of the milled FFRS to the milk replacers resulted in higher digestibilities of dry matter, nitrogen and energy and better retention of nitrogen than when the unmilled FFRS was added. However, the colloid-milled FFRS diet still was not as highly digestible as the all-milk diet. Increasing the level of substitution with milled FFRS from 25 to 50% produced a further decrease of about 4 units in the digestion coefficients and of 9 units in the retention of nitrogen expressed as a percent of the intake. Serum cholesterol levels just prior to and 2 h after feeding were not affected by the dietary treatments. Histology of liver biopsy samples taken at 22 days of age and of hearts and livers at market weight showed no detrimental effect on these organs from feeding low-erucic acid, low-glucosinolate FFRS to lambs. Based on growth trials it is concluded that low-erucic acid, low-glucosinolate FFRS, after colloid milling, can replace from 25 to 50% of the milk protein and most of the fat in lamb milk replacers without significantly affecting animal performance.