نوع مقاله : مقاله پژوهشی
نویسندگان
گروه علوم دامی دانشگاه فردوسی مشهد
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction: In livestock rearing, providing a balanced diet for animal in order to produce meat and milk is the main component of this profession. Due to the limited rainfall and lack of good forage resources in Iran, nutrition has the highest cost share in livestock production. Therefore, identifying local source of animal feed and determining their nutritional value is essential. Because using these local feed sources in addition to reducing feed costs, prevents the depletion of these natural resources and increases employment. Reed fodder is one of the available forage species in many parts of the world, including Iran, and has a good potential for using in livestock feeds. This plant grows abundantly in wetlands and on the banks of most rivers in the country. Despite the severe shortage of livestock feed in Iran, the reed fodder is not used properly in livestock feeds. The crude protein, crude fiber and calcium amounts of reed fodder are 11.4%, 31% and 0.17 %, respectively. A cow weighing 300 kg needs 6 %digestible protein for 500 g daily gain, which reed fodder can supply half of the digestible protein and all the calcium and phosphate. The expansion of the livestock feed industry made it perfect feed for the various stages of growth of the most types of livestock. Complete feed block (CFB) is composed of forage, concentrate, and other supplementary nutrients in a desired proportion, which is capable to fulfill nutrient requirements of animals. The feeding of CFB stabilizes rumen fermentation, minimizes fermentation loss, and ensures better ammonia utilization. Advantages of CFB are using local feed raw materials which are cheaper and easier in distribution, because the distance between the processing place and the farm is closer. Also, it has a competitive advantage compared with commercial feed manufactured in large industrial scale; because, it is more efficient in production, it is lower in transportation costs and easier in storage, and it can reduce operating costs, especially labor. The type of feed will prevent selective feeding of animals;then, nutrients are provided more evenly by rumen microorganisms. There are few studies on the use of reed fodder in complete feed block form. Therefore, the main objective of this study was to evaluate the effects of diet containing reed fodder (Phragmatis australis) in the form of complete feed block on growth performance of Baluchi lambs.
Material and methods: Thirty male lambs with an average age of 5 to 6 months and weight of 28±2.9 kg were fed with complete diets based on 30% forage and 70% concentrate. The experimental diets were: 1) total mixed ration containing alfalfa hay and wheat straw as the control, 2) complete feed block containing reed fodder as block diet, and 3) total mixed ration containing reed fodder as mixed diet. The experiment was conducted in a completely randomized design with three treatments and 10 replications. Animals were fed the experimental diets for 105 days, and daily feed intake were recorded. A digestion trail for seven days were conducted at the middle of experimental feeding, and daily feed intake and feces excretion were recorded. At the end of experiment, rumen fluid samples were taken from each animal at 3 h after morning feeding. Concentration of NH3-N was determined for rumen fluid samples according to Broderich and Kang (1980), and VFA were analyzed according to Ervin et al. (1961). Rumen fluid was used to direct count of protozoa using the methods of Dehority (2003). The chewing activities were recorded through a visual observation method for a period of 24 h continuously (08:00 to 08:00 the next day) at 5 – min intervals. Blood samples from jugular vein were collected in serum tubes containing anticoagulant agent approximately 4 h after morning feeding.
Results and discussion: Feed intake (g/day), weight gain (g/day), and final weight (kg) of lambs fed with control and block diets were higher than those fed with mixed diets (P˂0.05). Apparent digestibility of DM, NDF, ADF, and CP in lambs fed with control and block diets were higher (P˂0.05), but no significant difference was observed between lambs fed with control and block diets. In lambs receiving the mixed diet, the NH3-N concentration was lower and the ratio of acetate to propionate was higher (P˂0.05), but no significant difference was observed between lambs receiving the control and block diets. The pH of rumen fluid as well as concentrations of isovaleric acid and valeric acid were not affected by experimental treatments. The whole rumen protozoa population and the population of Entodiniums and Epidiniums were higher in lambs fed with block diet (P˂0.05), but no significant difference was observed between lambs fed with the control and mixed diets. The concentration of blood urea nitrogen (BUN) was lower in lambs fed with the control and block diets (P˂0.05), but no significant difference was observed between lambs fed with the control and block diets. Other blood metabolites were not affected by experimental diets. The physical form of the feed (block diet) significantly increased the eating rate, ruminating rate, and total activity of the chewing (P˂0.05). Compared to lambs fed with block and mixed diets, lambs fed with control diet spent more time for eating, ruminating, and chewing. Feed conversion ratio of lambs fed with diets containing reed fodder was not affected by the physical form of the feed. Probably the decrease in air temperature during the fattening period affected the feed conversion ratio, and it was more effective for lambs fed with mixed diet with rough feed. The cost of feed per kilogram of live weight gain during the fattening period for each of the control, block, and mixed diets was calculated as 76630, 66360 and 67270 Rials, respectively. Based on these results, the use of reed fodder in the form of cubic blocks was more economical than the other two treatments.
Conclusion: The results of this experiment support the positive effects of using diets containing reed fodder in the form of complete feed block with the lower costs in areas which have the potential for growth of reed fodder.
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