نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Introduction: The identification and utilization of regionally available feed resources are essential, particularly given the substantial influence of environmental and climatic factors on the quality and nutritional composition of forage crops. Under conditions of increasing water scarcity and the limited availability of conventional forages, the use of drought- and salinity-tolerant plant species such as camelthorn (Alhagi maurorum) has attracted growing interest. Camelthorn is considered a promising alternative forage owing to its relatively high concentration of digestible protein and a wide array of essential nutrients, contributing to its classification as a functional feed ingredient. Previous research has demonstrated that the partial substitution of traditional forages with camelthorn, particularly during their vegetative or flowering stages, does not adversely affect ruminal fermentation, nutrient digestibility, or overall animal performance. Although camelthorn hay is widely available in arid and semi-arid regions of Iran and has the potential to meet the nutritional demands of grazing livestock, its comprehensive nutritional profile remains insufficiently studied. Moreover, information regarding the use and nutritive value of halophytic plants in ruminant nutrition is generally scarce. Accordingly, the present study aimed to investigate the effects of replacing alfalfa hay with graded levels of camelthorn hay on apparent nutrient digestibility, ruminal fermentation characteristics, microbial protein synthesis, and ruminal papillae morphology in fattening lambs.
Materials and Methods: This experiment was conducted using 20 male Arabian lambs, aged 3-4 months, with an average initial body weight of 22.4 ± 1.5 kg. The study lasted 84 days, comprising a 14-day adaptation period followed by 70 days of experimental feeding. Lambs were individually housed and randomly assigned to one of four dietary groups in a completely randomized design, with five lambs per group. The experimental groups were as follows: 1) Control diet containing alfalfa hay without camelthorn hay; 2) diet with 33.3% replacement of alfalfa hay with camelthorn hay; 3) diet with 66.6% replacement of alfalfa hay with camelthorn hay; and 4) diet with 100% replacement of alfalfa hay with camelthorn hay. All diets were formulated using the Small Ruminant Nutrition System (SRNS) software and offered as total mixed rations (TMR) with a forage-to-concentrate ratio of 30:70, designed to meet the nutritional requirements of fattening lambs. Apparent nutrient digestibility was assessed using acid-insoluble ash as an internal marker. On day 84 of the study, rumen fluid samples were collected three hours after the morning feeding to analyze protozoal populations and volatile fatty acid (VFA) profiles. During the final week of the trial, urine was collected to estimate microbial protein synthesis using the purine derivatives excretion method. At the end of the trial, after slaughter, samples were taken from the rumen wall to evaluate the morphological characteristics of the rumen epithelium.
Results and Discussion: Apparent dry matter digestibility was significantly higher in the group receiving 33.3% replacement of alfalfa hay with camelthorn hay compared to the 66.6% and 100% replacement groups (P < 0.05). Apparent digestibility of acid detergent fiber (ADF) also differed significantly among groups (P < 0.05), with the highest value recorded in the control group (100% alfalfa; 45.67%) and the lowest in the 100% camelthorn group (32.63%). The apparent digestibility of non-fiber carbohydrates (NFC) was significantly higher in the group receiving 33.3% replacement of alfalfa hay with camelthorn hay and control groups compared to the other experimental groups (P < 0.05). Total volatile fatty acid (VFA) and acetate proportionwere significantly elevated in all camelthorn-containing diets relative to the control (P < 0.05). Conversely, the molar proportion of ruminal propionate was significantly greater in the control and 33.3% replacement groups compared to the 66.6% and 100% camelthorn groups (P < 0.05). Protozoal populations in the rumen fluid were significantly higher in lambs fed the diets with 66.6% and 100% camelthorn substitution (P < 0.05). Furthermore, urinary excretion of allantoin, total purine derivatives, and estimated microbial protein synthesis were significantly increased in all camelthorn-supplemented groups compared to the control (P < 0.05). With respect to rumen morphology, papillae height was significantly greater in the 66.6% and 100% camelthorn groups than in the 33.3% and control groups (P < 0.05). Papillae density also significantly increased in all camelthorn groups relative to the control diet (P < 0.05).
Conclusion: The results of this study indicate that the graded substitution of alfalfa hay with camelthorn hay significantly influenced nutrient digestibility parameters, rumnial fermentation characteristics, and microbial protein synthesis in fattening lambs. Notably, the 33.3% replacement level preserved favorable digestibility while enhancing specific fermentation indices, suggesting it may be the optimal inclusion level. Given the increasing global demand for alfalfa, camelthorn offers a viable, cost-effective alternative forage in fattening lamb diets, warranting its consideration as a sustainable feed resource.
کلیدواژهها English
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