| Description: |
It was hypothesized that the efficiency of canola meal ( CM ; also known as 00 rapeseed meal) utilization in pelleted starter mixtures for calves can be increased with the use of feed additives and additional processing. Additionally, it was hypothesized that CM would yield greater feed intake, growth, and improved fecal scores compared to wheat bran and DDGS when included as a high-protein by-product in a pelleted starter mixture. In order to verify the hypotheses, four studies were conducted to determine whether lysine ( Lys ) inclusion, feed enzyme inclusion, and CM extrusion improve the efficiency of CM utilization in pelleted calf starter mixtures, and to compare effects of CM to that when other high-protein by-products are fed. In study 1, 45 female Holstein calves (44.7 ± 4.2 kg, 24.2 ± 2.8 days of age) were allocated to one of three treatments and fed a pelleted starter mixture containing: 1) soybean meal ( SBM ) as the main source of protein ( TSBM ); 2) CM as the main source of protein ( TCM ); or 3) CM as the main source of protein with supplemental rumen-unprotected Lys ( TCML ). Final body weight ( BW ), average daily gain ( ADG ), starter intake, and fecal score did not differ among treatments ( P ≥ 0.20) but the gain to feed ratio was greater for TSBM than for TCM and TCML ( P < 0.01). No differences between TCM and TCML were found. In study 2, 100 female Holstein calves (44.3 ± 4.8 kg, 17.7 ± 2.1 days of age) were assigned to one of four treatments and fed pelleted starter mixtures with: 1) low CM inclusion (10%; LOW ); 2) low CM inclusion supplemented with feed enzymes (xylanase, glucanase, invertase, protease, cellulase, amylase, and mannanase; LOW+ ); 3) high CM inclusion (32%; HIGH ); and 4) high CM inclusion supplemented with the same feed enzymes ( HIGH+ ) as for LOW+. In treatments that included feed enzymes, final BW, ADG, and starter intake were greater while the number of days with diarrhea was lower ( P ≤ 0.05). The number of days with diarrhea was also lower for high CM ... |