Document Type : Research Paper

Authors

• Ali Asadi ¹
• Ali Kiani ²
• Ayoub Azizi ³
• Ali Forouharmehr ⁴
• Amir Fadayifar ⁵

¹ Department of Animal Science, Lorestan University, Khorramabad, Iran. E-mail: asadi.al@lu.ac.ir

² Corresponding Author, Department of Animal Science, Lorestan University, Khorramabad, Iran. E-mail: kiani.a@lu.ac.ir

³ Department of Animal Science, Lorestan University, Khorramabad, Iran. E-mail: azizi.ay@lu.ac.ir

⁴ Department of Animal Science, Lorestan University, Khorramabad, Iran. E-mail: forouharmehr.a@lu.ac.ir

⁵ Department of Animal Science, Lorestan University, Khorramabad, Iran. E-mail: fadayifar.a@lu.ac.ir

Abstract

Objective: Soybean meal is the most commonly fed protein source in ruminant nutrition. Soybean meal protein has moderate ruminal degradability (45-70%) and is deficient in  methionine,. which negatively impacts  the efficiency of nitrogen utilization in the diet and the environmental impact  of excess nitrogen in the urine. This combination of problems, plus market shortages, has spurred the search for suitable replacements for soybean meal. Alternative protein sources such as corn gluten meal and fish meal have a higher rumen-undegradable protein fraction and greater methionine and lysine content than soybean meal. The aim of the present study was to assess the effects of replacing soybean meal partially by corn gluten meal and fish meal on performance, physicochemical characteristics (pH and water-holding capacity, cooking loss) and fatty acid profile of meat in fattening male lambs.
Method: A completely randomized design was used to study the effect of three experimental treatments (7 lambs per treatment on feed intake, daily weight gain, and feed conversion ratio (FCR) of 21 male Lori-Bakhtiari lambs (age: 120±15 days, initial weight: 33±2.5 kg) fed individually for 75 days (including a 15-day adaptation period)  with diets containing 13% soybean meal, 5% soybean meal + 3.5% corn gluten meal, or 5% soybean meal + 2% corn gluten meal + 2% fish meal. All diets had aratio of rumen-degradable protein (63%) to rumen-undegradable protein (37%). After slaughter,the physicochemical characteristics and fatty acid profile of the meat were determined.
Results: There was no effect of replacing soybean meal with corn gluten and fish meal ondry matter intake. The final weightm daily weight gain  and FCR were all significantly better (P<0.05) for lambs fed a diet containing a mixture of three protein sources (soybean meal+corn gluten+fish meal) compared to other lambs.. Replacing of soybean meal with corn gluten and fish meal did not affect the moisture, fat, and mineral percentages of the lamb meat, but it decreased  the protein percentage of the lamb meat (P< 0.05). The physicochemical characteristics of the lamb meat were also not affected by the replacement of soybean meal with corn gluten and fish meal. Generally, partial replacement of soybean meal by 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, but, the percentages of arachidic acid (C20:0) and docosahexaenoic acid (C22:6) were higher in the meat of lambs fed a diet containing corn gluten + fish meal compared to those fed soybean meal (P<0.05). 
Conclusion: Results of the present study revealed that replacing soybean meal with a mixture of corn gluten and fish meal improved growth performance without  affecting the physicochemical characteristics  and the fatty acid profile of the meat in fattening lambs.

Keywords

• Fattening lamb
• Meat fatty acids
• Rumen Undegradable Protein
• Physicochemical properties of meat