Heat- and Lignosulfonate-Treated Canola Meal as a Source of Ruminal Undegradable Protein for Lactating Dairy Cows

Abstract

This experiment used 18 lactating Holstein cows in a 3 3 Latin square replicated 6 times to determine the effectiveness of processing with moist heat or moist heat combined with lignosulfonate (LSO 3 ) for increasing the ruminal undegradable fraction of canola meal for use as a protein supplement for lactating dairy cows. Diets were formulated to be isonitrogenous and contained one of 3 forms of canola meal; untreated canola meal (UCM), heat-treated canola meal (HTCM) or heatand LSO 3 -treated canola meal (LSO 3 CM). Total collection of urine and feces was taken from each cow during the last 5 d of each 42-d experimental period. Milk production was greater for cows fed the LSO 3 CM diet (36.6 kg/d) than for cows fed the UCM diet (34.8 kg/d) but did not differ from cows fed the HTCM diet (35.3 kg/d). Digestibility of crude protein was lower for cows supplemented with LSO 3 CM and they had reduced concentrations of ruminal ammonia N, blood urea N, and milk urea N compared with cows supplemented with UCM or HTCM. Dry matter intake and apparent digestibilities of neutral and acid detergent fiber were increased in cows fed the LSO 3 CM diet. Urinary N excretion (as % of N intake) was reduced in cows fed the LSO 3 CM diet. These results indicate that moist heat combined with LSO 3 treatment of canola meal was effective in increasing the proportion of crude protein digested in the lower digestive tract of lactating cows and was therefore used more effectively as a source of protein than UCM or HTCM.