The effect of urea processed canola straw on nutrients digestibility, growth performance and blood parameters of Dalagh rams

About 70% of the cost of livestock breeding is related to feed, so the preparation of balanced diet with inexpensive ingredients can play an important role in the profitability of production in breeding. One of the cheapest sources of feed for ruminant animals is the agricultural by-products that are not consumed by humans. Canola Straw is one of the major agricultural by products in Golestan province whose digestibility is low because of containing high amounts of lignocellulosic materials. Processing lignosellulotic feeds with alkaline components can improve their digestibility throw breaking cellulos-lignine bonds. This research was conducted to investigate the effect of canola straw processing with urea on feed digestibility and weight gain performance and some blood parameters of fattening lambs.

For this purpose, 18 5-month-old male lambs of the Dalaqh breed (30-35 kg body weight) were randomly assigned to three nutritional treatments. The control treatment was a fattening diet with a ratio of forage (alfalfa and straw in equal proportions) to concentrate 64:36. In the second treatment, 50% of wheat straw was replaced with untreated canola straw and in the third treatment with urea treated canola straw. After a two-week habituation period with the same ration and initial weighing, experimental rations were fed to the lambs and continued until the end of the 70-day fattening period. During this period, the lambs were weighed every 14 days. At the end of the period, the lambs were weighed and blood sampled. Blood samples were analyzed to determine the serum urea nitrogen, glucose and total protein concentrations. In order to determine the feed intake and digestibility, during two weeks, the remaining feed and feces samples of each animal were collected daily, and the amount of acid insoluble ash was used as an internal marker to calculate the digestibility of experimental feeds.

The average daily feed intake of lambs fed with a diet containing processed canola straw (925.00 gr.day-1) was significantly (P<0.05) higher than lambs fed with diet containing wheat straw or unprocessed canola straw (respectively 887.32 and 850.00 gr.day-1). Also average daily gain of lambs in treated canola straw group was significantly higher than untreated canola straw group (respectively 178.09 vs. 141.53, P<0.05), but feed treatments had no significant effect on feed conversion rate of lambs. Processing with urea significantly (P<0.05) increased the digestibility of dry matter, NDF and ADF (respectively 61.30, 71.11 and 35.30 %) compared to unprocessed canola straw (respectively 55.45, 66.42 and 27.96%) and control (respectively 58.80, 68.82 and 28.76 %). Processing canola straw with urea significantly (P<0.05) increased crud protein digestibility of diet compared to control (60.32 vs. 54.04 %). The levels of serum urea in treated canola straw treatment was significantly higher than untreated canola straw and wheat straw treatments (respectively 17.82, 15.50, 14.82 mg/dl, P<0.05), but the average serum glucose, total protein, total cholesterol and triglyceride levels were not significantly different among the treatments.

The results of this research showed that canola straw processing with urea can improve its nutritional value and nutrient digestibility, feed intake and weight gain performance of lambs.