Effects of using total mixed ration silage based on alfalfa forage with or without wheat straw on performance, meat quality, and blood and rumen parameters in fattening lambs

Background and objectives: Little information is available about the effect of fermented total mixed rations (FTMR) based on alfalfa forage on he performance, quality and oxidation rate of meat fat, rumen parameters and blood of fattening lambs. On the other hand, due to the wrong way of storing alfalfa in Iran, the main part of its protein is lost, which is in the leaves of plant. In addition, when it is not possible to dry alfalfa, it is necessary to provide a suitable method for its storage. Also, the use of FTMR leads to better feed management and preservation of its nutritional value. The purpose of the present study was to survey effects of feeding total mixed ration silage based on alfalfa forage with or without wheat straw on performance, meat quality, blood and rumen parameters in fattening male lambs.
Materials and methods: Thirty Kermani male lambs (with an average initial weight of 20.5±0.5 kg and six months’ age) were divided into three groups of ten as completely randomized design. Each group was assigned an experimental diet. Experimental diets include: 1) CON, fresh TMR with alfalfa hay; 2) FTMR with fresh-cut alfalfa without wheat straw; and 3) FTMR with fresh-cut alfalfa and wheat straw. To estimate feed intake, the remaining feed of lambs is collected and weighed daily before the morning meal. At the end of every two weeks the lambs are weighed for calculation of daily weight gain. At the end of the fattening period, the rumen fluid of the lambs was sampled at 0 and 3 hours after feeding through the esophageal tube connected to the suction device to determine pH, NH3-N, protozoa population and volatile fatty acids. On the last day of the period and one hour before feeding, blood was taken from the lambs from the jugular vein to determine biochemical parameters. Then the lambs were killed at the end of the period and after a night of starvation and their warm and cold carcasses were weighed. In order to measure pH, water holding capacity, cooking loss, dripping loss, and the amount of fat oxidation, a sample was taken from the eye muscle and packed in air-insulated nylon bags and kept at -20 °C until evaluation.
Results: The results of the research showed that the dry matter intake and feed conversion ratio of lambs fed FTMR with wheat straw was higher compared to the other experimental groups (P<0.05). Also, final weight, daily weight gain, warm and cold carcass weight, cold carcass percentage and carcass loss in lambs fed FTMR with wheat straw were higher compared to other groups (P<0.05). The ruminal propionic acid in lambs fed FTMR with wheat straw was higher (P<0.05) compared to control group. The pH, NH3-N concentration and protozoa population were not affected by experimental diets. The blood triglyceride level of lambs fed FTMR with wheat straw was lower compared to other experimental groups (P<0.05). Also, blood glucose was higher in lambs fed TMRS with wheat straw compared to other groups (P<0.05), but liver enzymes, blood urea nitrogen and cholesterol were not affected. Also, the cooking loss, dripping loss, malondialdehyde, water holding capacity and pH of the meat were not affected by the experimental diets.
Conclusion: In general, based on the obtained results, it is possible to provide complete and balanced rations while maintaining the quality of alfalfa forage, especially for small-scale farmers, by producing TMRS with fresh alfalfa. On the other hand, considering the results in vivo and improving the performance of lambs, it is possible to use TMRS based on fresh fodder in feeding fattening animals.