Use of canola meal as a protein source in pelleted starter mixtures for dairy calves
Evaluate the effectiveness of canola meal as a protein source in pelleted starter mixtures for newborn calves and to determine suitable methods of increasing canola meal digestibility and palatability. To compare canola meal and soybean meal in terms of their effectiveness to stimulate gastrointestinal development in calves at weaning.
Canola meal use in starter mixtures for calves is limited. The objective of this study was to evaluate the use of canola meal as a protein source in starter mixtures for Holstein calves around weaning and to evaluate strategies that may enhance canola meal use and improve gastrointestinal development. Four studies were conducted to address the previously mentioned objectives. The first study evaluated the impact of heating canola meal on in situ digestibility and estimated intestinal digestibility. We found that heating canola meal to 110°C increased the rumen undegradable fraction without negatively affecting the intestinal digestibility. In the second study, canola meal was either not heated or heated as described for Study 1. The starter mixtures incorporated canola meal (not heated vs. heated) with or without glycerol. A total of 28 Holstein bull calves were sourced for this study and randomly assigned to 1 of the 4 starter mixture treatments in a 2 x 2 factorial treatment arrangement. We observed that heat-treating canola meal tended to decrease average daily gain and broadly reduced GIT tissue mass. Interestingly, glycerol inclusion, in general, had a positive effect on growth, ruminal fermentation, insulin concentration, and may alter GIT development. Study 3 contained metabolic and growth performance components. Treatments included canola meal or soybean meal as the protein source with or without microencapsulated sodium butyrate. Our findings suggest that, relative to soybean meal, canola meal may negatively affect starter mixture intake and body weight gain. However, we also found that microencapsulated sodium butyrate stimulated starter mixture intake and intestinal development. Studies 1 to 3 suggested that replacing soybean meal with canola meal may decrease starter mixture intake and that heat-treating canola meal exacerbated the effect. However, both glycerol and microencapsulated sodium butyrate had positive effects. The final study was conducted to evaluate how canola meal inclusion affects production responses. In this study (Study 4) we substituted 0, 50, or 100% of the soybean meal with canola meal. We found that full replacement of soybean meal with canola meal reduced starter intake but, replacement of 50% of the soybean meal was acceptable for calves. Altogether, the results of this study suggest that high-quality canola meal can be used in starter mixtures for dairy calves and that the inclusion of glycerol and microencapsulated sodium butyrate stimulate starter intake, growth performance, and aspects of gastrointestinal development.