Forage quality is a key factor in dairy cattle nutrition. High moisture forages are so susceptible to loss their nutrients during ensiling. Canola is one of the oilseed plants that belong to Brassica species. Canola forage has high level of moisture in its tissues and must be wilted to 60 -65% moisture before ensiling. On the other hand, molasses and urea as two silage additives can be effective in improvement and preservation of canola forage quality. Molasses is commonly used to provide readily available energy for lactic acid fermentation. Addition of molasses can increase dry matter content of silage that related to relatively high dry matter content of molasses (Baytok and Aksu, 2005). Meanwhile, silage protein content can be increased and proteolysis decreased with the addition of urea. Application of urea to harvested forage before ensiling can restrict the fermentation processes and release ammonia to potentially enhance nutritive value of the ensiled crop and reduce deterioration during storage. The main objective of this study was to evaluate effects of different levels of urea and molasses on chemical composition and in vitro DM digestibility of whole crop canola silage.

It is clear that providing sufficient fiber in dairy cattle diets has most positive effects on improvement of rumen ecosystem and feed intake efficiency. In semiarid countries such as Iran providing forage requirement of cattle is limited. So it is better to use plants with low water requirement, high growth rate and high forage yield per hectare. Canola (Brassica napus L.) recently has received consideration as a forage source for livestock (Lancaster et al., 1990). Canola is reasonably widely adapted and performs well in many areas of Iran. In addition to its low water requirements and high growth rate, its cultivation season is well matched with environmental condition in Iran. The main objective of this study was to evaluate effect of replacing maize silage with canola silage (as dry matter %) on Holstein dairy cow performance.

Introduction: Providing good quality forage in dairy cattle diet is vital for the dairy farm industry. Canola forage was newly added to dairy cows’ diet in Iran. The present study aimed to determine the effects of replacing corn silage with canola silage on feed intake, apparent digestibility, milk yield, milk composition, and thyroid hormone levels of dairy cattle in Mashhad, Iran. Materials and methods: Nine Holstein cows were used in this study and were allocated in a 3×3 change over Latin square design study. The trial consisted of 3 periods, each lasting for 20 days. The first 15 days were considered an adaptation period. Experimental diets were formulated to provide 33% of the total dry matter (DM) as forage. Canola silage was substituted with corn silage at levels of 0, 50, and 100% of DM. Results: Dietary concentrations of neutral detergent fiber (NDF) and acid detergent fiber increased when corn silage was replaced by canola silage. Replacing corn silage with canola silage caused a significant decrease in DMI. The apparent digestibility of DM and crude protein were not affected by the dietary replacement of corn silage with canola silage; however, organic matter and digestibility of NDF decreased significantly. When corn silage was replaced by canola silage, there were no significant changes in milk yield, fat-corrected milk, and milk composition in the investigated cattle, but milk protein changed significantly. The results indicated that 50% substitution of canola silage caused higher milk protein. Rumen fluid pH and its ammonia nitrogen concentration increased significantly in experimental animals. The concentrations of T3 and T4 decreased, whereas blood urea nitrogen concentration increased by dietary replacement of corn silage with canola silage. Conclusion: Canola silage can be substituted with corn silage, and feeding canola silage can be beneficial in some aspects.