عنوان مقاله [English]
Introduction: Various method have been used to evaluating the digestibility coefficients of nutrients. Total fecal collection method (TFC) is a reliable method for determining the digestibility of rations using live animals. In this method, animal are kept in a metabolic cage in to collect all the feces, making it the most accurate method for measuring feed digestibility. Total collection of faeces (TCF) is one of the most accurate direct procedures to determine apparent digestibility. Despite its accuracy, TFC is labor-intensive and time-consuming when evaluating a wide range of feed samples and requiring a large number of animals. Moreover, animals should be confined in stalls, considering that being surrounded will be accepted by camels for a short period and training is necessary for camels fed with ration contain-ing high amounts of energy. Other dis-advantage of keeping the animal trapped includes the po-tential impact on animal metabolism. These problems led to separation from the animal's normal behavior. Accurate measurement of food intake and fecal collection is a tough work. Digestibility coefficients can be measured indirectly by markers. Various indigestible markers include polyethylene Various indigestible markers include polyethylene, chromium oxide (Cr2O3), acid detergent lignin (ADL) and acid-insoluble ash (AIA) have been used to determine the digestibility of nu-trients in different parts of gastrointestinal tract. By the end of 19th century, lignin was considered as a po-tential internal marker for the estimation of digestibility. Because no specific enzymes exist for degradation of lignin in mammals or in anaerobic bacteria, different results have been re-ported by researchers when using ADL for the estimation of digestibility. Digestibility was reported to be underestimated when using AIA as a natural marker. However, it is difficult to apply this method to grazing animals. AIA is one of the most common internal indicators for determining apparent digestion coefficients. One of the advantages AIA compared to other markers is simplicity of analysis and it does not need special equip-ment. This study aims to evaluate the nutrient apparent digestibility of different diets in camels using AIA, ADL and TFC.
Materials and methods: The field phase of the research was conducted at Asrar Sabzevar Agricultural Research Station, and the laboratory phase was conducted at the Animal and Poultry Nutrition Laboratory of Gorgan University of Agricultural Sciences and Natural Resources. Four male camels (age=1 year, BW= 116.3±9.35 kg) were used in a completely random design to measure the apparent digestibility of nutrients in wheat straw and wheat straw with rice hull using AIA, ADL, and TFC. The experimental period was 42 days (2 periods of 21 days) with 14 days of adaptation to experimental diets and 7 days of data collection. Camels had free access to water, and feeding was done once a day at 8 A.M.
Results and discussion: The results showed no significant difference between TFC and AIA for measuring the digestibility of dry matter, organic matter, crude fat, crude protein, neutral detergent insoluble fibers, and acid detergent insoluble fibers in wheat straw and wheat straw with rice hull (P>0.05). However, digestibility was significantly higher in TFC than in ADL (P<0.05).
Conclusions: The recovery percentage of AIA marker was 92.8±92.38 in the diet of 75% wheat straw with 25% rice hull. Based on the study's results, AIA can be used as a suitable internal indicator to measure digestibility in camels if the recovery percentage is more than 90%. The amount of digestibility measured using AIA was close to the amount of digestibility measured using TFC.
Materials and methods: The field phase of the research was conducted at Asrar Sabzevar Agricultural Research Station and the laboratory phase was conducted at the Animal and Poultry Nutrition Laboratory of Gorgan University of Agricultural Sciences and Natural Resources. In this research, the apparent digestibility of food in camels in three ways according to the total amount of feces.We measured and compared the methods of acid-insoluble ash and acid-insoluble lignin. The test diets included wheat straw and wheat straw + rice bran. For this purpose, four male camels with an average weight of 116.25 ± 9.35 kg and an age of about one year were used in a completely random design. The camels were placed in the individual position. The experiment period was 84 days (4 periods of 21 days). Camels had free access to water and feeding was done once a day at 8 A.M. Before the seven-day collection period, the animals were acclimatized with the experimental diet for two weeks. Wheat straw digestibility and acid-insoluble ash recycling rate were also measured in experimental diets. In order to determine the apparent digestibility of feed nutrients, stool and feed samples were taken at the end of 7 days. Animal feces were sampled daily and finally the samples were mixed and homogenized and 500 grams of samples were prepared from each camel and the samples were kept at -20 degrees Celsius until analysis. The data obtained from three methods of determining digestibility for each ration were analyzed using SAS statistical software and compared using Duncan's test at a significant level of 5%. Regression equation and correlation coefficient were used to compare digestibility obtained by three methods.
Results and discussion: The results showed a significant difference between the methods of collecting total feces, acid-insoluble ash and acid-insoluble lignin to measure the digestibility of dry matter, organic matter, crude fat, crude protein, insoluble fibers in neutral detergent. There are insoluble fibers in acidic detergent and raw energy of wheat straw and wheat straw+rice bran (P<0.05).
Conclusions: The amount of digestibility of ash insoluble in acid was close to the amount of digestibility of collecting whole feces. Therefore, acid-insoluble ash method can be used for camel digestibility experiments.