A COMPARISON OF RAPESEED MEAL AND SOYBEAN MEAL AS A SOURCE OF PROTEIN AND PROTECTED LIPID AS A SOURCE OF SUPPLEMENTAL ENERGY FOR CALF STARTER DIETS

Abstract

Thirty male Holstein calves were utilized in a 2 × 3 factorial experiment designed to compare rapeseed meal (cv. Candle) and soybean meal as protein supplements and 0, 10, and 20% levels of protected lipid as a form of supplemental energy for starter rations. The six rations were fed free choice from 21 to 70 days of the experiment with whole milk fed at 10% of body weight from 0 to 42 days. Starter intake was similar for the two protein sources but significantly less for the ration containing 10% protected lipid compared to either the 0 or 20% levels. Body weight gain was faster for calves fed the starter containing 20% protected lipid compared to those fed the 10% level. Efficiency of feed conversion was greater for calves receiving protected lipid. There were no differences between protein source in dry matter intake, body weight gain, efficiency of feed conversion, apparent dry matter digestibility or dressing percent. Plasma glucose and percent hematocrit were significantly lower and percent kidney fat significantly higher for calves fed starter rations containing soybean meal. The relative availability of copper was reduced significantly when soybean meal or 20% protected lipid formed part of the starter diet. It was concluded from this study that Candle rapeseed meal was a suitable source of supplemental protein for calf starter diets and that the inclusion of protected lipid improved feed conversion of calves from 43 to 70 days of age.