1- Sari University of Agricultural and Natural Resources
Abstract: (23 Views)
Introduction and Objective: The identification and use of locally available feed resources are essential, particularly in light of the significant effects of environmental and climatic conditions on the quality and nutritional composition of forage crops. With increasing water scarcity and the limited availability of conventional forages, attention has turned to drought- and salinity-tolerant plant species such as camelthorn (Alhagi maurorum). Camelthorn is considered a promising alternative forage due to its relatively high content of digestible protein, essential minerals, and various bioactive compounds. It has been reported to be palatable to small ruminants, including goats and sheep. Previous research has shown that camelthorn, owing to its nutritional profile and chemical composition, can be incorporated into the diets of ruminants—especially camels, sheep, and goats—in arid and semi-arid regions; Its partial replacement for conventional forages is potentially sufficient to meet maintenance, gestation, and lactation requirements in these animals. The chemical composition of camelthorn is comparable to that of clover and alfalfa forages. In many regions, it has gained increasing recognition as a valuable forage resource and is commonly harvested manually for this purpose. Given that large areas of Iran are classified as arid or desert zones, with approximately 12.5% of the land affected by saline and alkaline soils, the use of halophytic species such as camelthorn could offer a sustainable feed resource, particularly during dry seasons. Therefore, this study was conducted to evaluate the effects of replacing alfalfa hay with varying levels of camelthorn forage in the diet on growth performance, blood biochemical parameters, liver enzyme activities, carcass quantitative traits, and the chemical composition of meat in fattening male lambs.
Materials and Methods: This experiment was conducted using 20 male Arabic lambs, aged 3 to 4 months, with an average initial body weight of 22.4±1.5 kg. The study lasted for 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 treatments in a completely randomized design (CRD), with five lambs per treatment. The dietary treatments 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. Parameters including daily dry matter intake, average daily gain, and feed conversion ratio were recorded throughout the experimental period. On day 84, blood samples were collected from the jugular vein prior to the morning feeding to determine blood metabolites and liver enzyme concentrations. At the end of the trial, 15 lambs (three from each treatment group, selected based on average group body weight) were slaughtered to assess carcass yield and meat quality attributes. Data were analyzed as a completely randomized design using the General Linear Model (GLM) procedure of SAS.
Results: The results indicated that average daily gain (ADG), daily feed intake (DFI), and feed conversion ratio (FCR) throughout the experimental period were not significantly affected by the replacement of alfalfa hay with varying levels of camelthorn forage (P > 0.05). Although the differences were not statistically significant, a trend was observed whereby total daily feed intake increased with higher levels of camelthorn substitution, with the highest intake recorded in the group receiving 100% camelthorn forage. Blood concentrations of glucose, triglycerides, high-density lipoprotein (HDL), very low-density lipoprotein (VLDL), total protein, albumin, and plasma urea nitrogen did not differ significantly among the dietary treatments (P > 0.05). However, cholesterol (P = 0.0330) and low-density lipoprotein (LDL) (P = 0.0263) concentrations were significantly higher in the 33.3% camelthorn and control groups compared to the 66.6% and 100% camelthorn replacement groups. Complete replacement of alfalfa hay with camelthorn forage significantly reduced the levels of liver enzymes aspartate aminotransferase (AST; P = 0.0034) and alanine aminotransferase (ALT; P = 0.0003). None of the carcass traits, including live weight, hot and cold carcass weight, half-carcass weight, and the weights of the shoulder, leg, and loin, differed significantly among the treatment groups (P > 0.05). However, the dry matter content (P = 0.0307) and organic matter content (P = 0.0056) of the meat were significantly higher in the control and 33.3% camelthorn groups compared to the 66.6% and 100% replacement groups. The crude protein content of the meat was significantly reduced in the 66.6% and 100% camelthorn groups (19.65% and 19.17%, respectively) compared to the control group (P = 0.0234).
Conclusion: The results of this study indicated that replacing varying levels of camelthorn forage (0%, 33.3%, 66.6%, and 100%) with alfalfa hay in the diets of fattening lambs did not adversely affect growth performance. Furthermore, the substitution improved the antioxidant status and lipid metabolism in blood plasma. Given the increasing global demand for alfalfa hay, incorporating camelthorn as a cost-effective forage alternative in the diets of fattening lambs is recommended.
Materials and Methods: This experiment was conducted using 20 male Arabic lambs, aged 3 to 4 months, with an average initial body weight of 22.4±1.5 kg. The study lasted for 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 treatments in a completely randomized design (CRD), with five lambs per treatment. The dietary treatments 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. Parameters including daily dry matter intake, average daily gain, and feed conversion ratio were recorded throughout the experimental period. On day 84, blood samples were collected from the jugular vein prior to the morning feeding to determine blood metabolites and liver enzyme concentrations. At the end of the trial, 15 lambs (three from each treatment group, selected based on average group body weight) were slaughtered to assess carcass yield and meat quality attributes. Data were analyzed as a completely randomized design using the General Linear Model (GLM) procedure of SAS.
Results: The results indicated that average daily gain (ADG), daily feed intake (DFI), and feed conversion ratio (FCR) throughout the experimental period were not significantly affected by the replacement of alfalfa hay with varying levels of camelthorn forage (P > 0.05). Although the differences were not statistically significant, a trend was observed whereby total daily feed intake increased with higher levels of camelthorn substitution, with the highest intake recorded in the group receiving 100% camelthorn forage. Blood concentrations of glucose, triglycerides, high-density lipoprotein (HDL), very low-density lipoprotein (VLDL), total protein, albumin, and plasma urea nitrogen did not differ significantly among the dietary treatments (P > 0.05). However, cholesterol (P = 0.0330) and low-density lipoprotein (LDL) (P = 0.0263) concentrations were significantly higher in the 33.3% camelthorn and control groups compared to the 66.6% and 100% camelthorn replacement groups. Complete replacement of alfalfa hay with camelthorn forage significantly reduced the levels of liver enzymes aspartate aminotransferase (AST; P = 0.0034) and alanine aminotransferase (ALT; P = 0.0003). None of the carcass traits, including live weight, hot and cold carcass weight, half-carcass weight, and the weights of the shoulder, leg, and loin, differed significantly among the treatment groups (P > 0.05). However, the dry matter content (P = 0.0307) and organic matter content (P = 0.0056) of the meat were significantly higher in the control and 33.3% camelthorn groups compared to the 66.6% and 100% replacement groups. The crude protein content of the meat was significantly reduced in the 66.6% and 100% camelthorn groups (19.65% and 19.17%, respectively) compared to the control group (P = 0.0234).
Conclusion: The results of this study indicated that replacing varying levels of camelthorn forage (0%, 33.3%, 66.6%, and 100%) with alfalfa hay in the diets of fattening lambs did not adversely affect growth performance. Furthermore, the substitution improved the antioxidant status and lipid metabolism in blood plasma. Given the increasing global demand for alfalfa hay, incorporating camelthorn as a cost-effective forage alternative in the diets of fattening lambs is recommended.
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