Document Type : Research Paper
Authors
1 Animal Science Group, Lorestan University, Khoramabad, Iran
2 Animal Science Group, Lorestan University, Khoramabad, Iran.
Abstract
ABSTRACT
Objective: Soybean meal is the most widely used protein source in ruminant nutrition. The ruminal degradability of soybean meal protein is relatively high (between 45-70%) and suffers from an amino acid imbalance (methionine deficiency). These characteristics not only reduce the efficiency of nitrogen utilization in the diet but also lead to environmental problems caused by the excretion of excess nitrogen in urine. The aforementioned issues, along with market shortages, necessitate the use of suitable alternatives to soybean meal. Feedstuffs such as corn gluten meal and fish meal are protein sources that have both a higher rumen-undegradable protein fraction and greater methionine and lysine content compared to soybean meal. Therefore, the objective of the present study was to investigate the effects of partially replacing soybean meal with corn gluten meal and fish meal on performance, physicochemical characteristics (The pH and water-holding capacity, cooking loss) and fatty acid profile of meat in fattening male lambs.
Methods: A total of 21 male Lori-Bakhtiari lambs (age: 120 ± 15 days, initial weight: 33 ± 2.5 kg) were used in a completely randomized design with three experimental treatments (7 lambs per treatment): 1) Diet containing 13% soybean meal, 2) Diet containing 5% soybean meal + 3.5% corn gluten meal and 3) Diet containing 5% soybean meal + 2% corn gluten meal + 2% fish meal.The lambs were individually fed for 75 days (including a 15-day adaptation period). The ratio of rumen-degradable protein (63%) to rumen-undegradable protein (37%) was the same for all diets. Feed intake, daily weight gain, and feed conversion ratio were calculated. At the end of the experiment, the lambs were slaughtered, and the physicochemical characteristics and fatty acid profile of the meat were determined.
Results: The dry matter intake was not affected by the replacement of soybean meal with corn gluten and fish meal. Lambs fed a diet containing a mixture of three protein sources (soybean meal+corn gluten+fish meal) had significantly higher final weight and daily weight gain and a better feed conversion ratio compared to other lambs. The moisture, fat, and mineral percentages of the lamb meat were not affected by the replacement of soybean meal with corn gluten and fish meal. However, replacing soybean meal with corn gluten and fish meal led to a decrease in the protein percentage of the lamb meat (P < 0.05). The physicochemical characteristics of the lamb meat were not affected by the replacement of soybean meal with corn gluten and fish meal. In most cases, the partial replacement of soybean meal with corn gluten and fish meal did not significantly affect the concentration of fatty acids in the meat (as a percentage of total fatty acids) in male lambs. However, the percentages of arachidic acid (C20:0) and docosahexaenoic acid (C22:6) were significantly higher in the meat of lambs fed a diet containing corn gluten + fish meal compared to those fed soybean meal.
Conclusion: The results of the present study indicated that replacing soybean meal with a combination of corn gluten and fish meal improved growth performance, but had no effect on the physicochemical characteristics and the fatty acid profile of the meat in fattening lambs.
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