EFFECTS OF TOWER AND 1821 RAPESEED MEALS AND TOWER GUMS ON MILK YIELD, MILK COMPOSITION AND BLOOD PARAMETERS OF LACTATING DAIRY COWS

Abstract

The effects of 1821 and Tower rapeseed meals (RSM) and Tower gums on feed intake, milk yield and composition, iodine and thiocyanate (SCN) content of milk and selected blood parameters were studied in two Lucas switch-back trials with lactating Holstein cows. Experimental treatments consisted of the sources of supplemental protein in the grain mixtures. In the first trial, Tower RSM at 26% and 1821 at 20 and 30% were compared to soybean meal (SBM) in grain mixtures balanced for protein and fiber content. Milk yield of cows receiving 30% 1821 RSM was greater than that of the control group (P < 0.05). There were no other treatment effects on feed intake, milk yield, fat, protein and solids not fat content of milk or plasma thyroxine levels (P > 0.05). Both Tower and 1821 RSM increased SCN and reduced iodine content of milk (P < 0.05). In the second trial, Tower RSM containing 0, 4 and 8% Tower rapeseed gums were compared to the SBM control. There were no treatment effects on feed intake, milk yield and composition (P > 0.05). Rapeseed meal decreased milk iodine content, increased milk SCN content (P < 0.01), and red blood cell concentration but decreased white blood cell concentration (P < 0.10). No effect on hemoglobin and packed cell volume was observed. There were no effects of level of gums on any of the above parameters.