| چکیده انگلیسی مقاله |
Extended Abstract
Introduction and Objective: In today's society, where we are facing an increase in the price of food items, it is very important to use agricultural by-products, industrial factories and waste from slaughterhouses and dairy industries in animal husbandry. One of these by-products is the poultry slaughterhouse waste powder, which is obtained during the production and processing of chicken meat. The successful replacement of these wastes with protein sources, including soybean meal, most of which is imported, while creating the correct balance between non-degradable protein and degradable protein in the rumen and a high-quality protein source, will reduce the cost of food rations and improve the economic status of livestock production and prevent environmental pollution. According to the mentioned cases, the aim of this research is the effect of replacing poultry slaughterhouse residue powder with soybean meal on feed consumption and ruminal parameters of Dalagh dairy ewes. Material and Methods: In this experiment, 20 ewes with 3 pregnancies of the Dalagh breed with an average weight of 36±3.7 kg were used in a completely randomized design (CRD) with 4 treatments and 5 replications. The treatments were including: control treatment (diet without poultry slaughterhouse residue powder), second treatment (diet containing 33 Percent replacement), third treatment (diet containing 66 Percent replacement) and fourth treatment (diet containing 100 Percent replacement of poultry slaughterhouse residue powder instead of soybean meal). Animals in each treatment were kept in individual cages for 42 days after ensuring their health. The ewes were weighed weekly and the feed and post-feed of each animal was recorded daily to calculate the dry matter consumption. Sampling of rumen fluid was done on the 42nd day of the experiment. The rumen fluid was taken in the morning before feeding (zero hour) and at three and six hours after feeding by esophageal tube, then the pH value of the rumen fluids was measured immediately after extraction by a mobile digital pH meter. It was calibrated, measured and recorded in the same place. To measure ammonia nitrogen in rumen fluid, samples 3 hours after morning feeding were used. After measuring the pH, the rumen fluid sample was filtered using a 4-layer cloth, and then the resulting sap was diluted with 0.2 normal hydrochloric acid at a ratio of 5 to 1 (five saps to one normal 0.2 HCl) and kept until the day of the experiment. The temperature was kept at -20°C. Broderick and Kang (1980) method was used to determine rumen ammonia nitrogen using a spectrophotometer at a wavelength of 630 nm. Ruminal fluid was sampled to measure the protozoan population on the last day. To count protozoa, the method of Dehority and Males (1984) was used. First, after straining the rumen liquid with a cloth, 4 ml of rumen liquid was poured into a test tube wrapped in foil, then 1 ml of formalin, 5 drops of methylene blue dye (2 grams of methylene blue with 100 ml Distilled water was added to the volume) and finally 3 ml of glycerol was added to the contents of the test tube. Protozoa counting was done by a stereomicroscope and a 40X magnification lens with a neobar slide. Counting was done 4 times for each sample and if there was a big difference between the counted protozoa, the counting was repeated. Finally, the number of protozoa per millimeter of rumen fluid was calculated. To measure volatile fatty acids, 5 ml samples of rumen fluid were prepared and 1 ml of 25% metaphosphoric acid was added to them and kept at -20°C until the experiment. Volatile fatty acids were determined using gas chromatography. The tested rumen enzymes were extracted in different parts of the rumen sap according to the method of Hristov et al. (2001). In order to divide the examined enzymes in the rumen sap into three solid, extracellular and intracellular parts, first the sap (about 50 ml) was filtered by a double layer of cloth and the remaining material on the cloth was considered as a solid part. To separate the protozoan and bacterial parts, the leachate was first centrifuged at 450g for 5 minutes at 37°C. Finally, the results of the experiment were analyzed with the GLM procedure of the SAS statistical program. Results: The amount of dry matter intake (DMI), the final weight of the ewes and the feed conversion ratio (FCR) were not affected by the experimental treatments. Among the different treatments, no significant difference was observed in terms of pH and protozoa population at three fasting times, three and six hours after feeding. While rumen NH3-N concentration was affected by the experimental treatments in such a way that by increasing the amount of poultry slaughterhouse residue powder in the diet, rumen NH3-N concentration also increased and the highest concentration of ammonia was observed in the treatment of 100 Percent replacement of poultry slaughterhouse residue powder with soybean meal (P<0.05). There was no significant difference in the concentration of acetate, propionate, butyrate, isovalerate, valerate and the ratio of acetate to propionate in the rumen, but the total concentration of VFAs in the rumen was affected by the experimental treatments and with the increase in the amount of poultry slaughterhouse residue powder in the diet, the concentration Total rumen VFAs increased (P<0.05). In terms of activity level of hydrolytic enzymes carboxymethylcellulase and microcrystalline cellulase (avicellase) in cellular, extracellular, solid and total parts, no significant difference was observed among experimental treatments.
Conclusion: In general, the results of this experiment showed that it is possible to completely replace poultry slaughterhouse residue powder with soybean meal without negative effects on feed intake and rumen health.
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