Effect of feeding a high- or low-rumen escape protein supplement to dry Holstein cows and heifers within 3 weeks of calving on their productive and reproductive performance in the subsequent lactation

Pregnant Holstein heifers (450) and dry cows (417) within 3 weeks of calving (i.e., close up) were assigned to one of three groups. These groups were offered a low-CP (0.117 of DM) ration based on corn silage, alfalfa cubes, oat hay, corn and barley grain, or a medium-CP (0.144) ration, as the low-CP ration plus 1 kg per day per cow of a supplement (0.60 canola meal or rumen protected (RP) canola meal and 0.40 other), or a high-CP (0.166) ration, as the low-CP ration plus 2 kg per day per cow of one of the supplements. Use of bovine somatotropin (bST), movement through production groups, and breeding events were determined by the herd manager after calving. Production parameters were pooled to means for cows that successfully completed the lactation. The RP canola meal had an average 0.720 rumen undegraded crude protein content, based upon 16 h in situ incubation, versus 0.252 for untreated canola meal. Primiparous cows produced no more milk or milk components in their full lactation, or had higher peak milk yields, if supplemented with canola meal at any level from either source. However average body condition score in lactation was higher (P