| چکیده انگلیسی مقاله |
Extended Abstract
Introduction and Objectives: The main chalange of animal production in the Iran is the lack of fodder, and to provide it, corn is one of the important agricultural crops, the level of cultivation and performance of which has increased significantly in the previous decades, and it is predicted that it is possible that the demand for corn will double the current demand by 2050. Many factors are involved in the increase or decrease of corn yield, but choosing a superior, compatible, and high-yielding hybrid in each region is one of the main factors in increasing the production and yield of corn crop. One of the limiting factors is the lack of water resources and the occurrence of droughts in the country in the last few years. In this regard, it is necessary to better understand the morphological characteristics of the plant, the performance of different hybrids and their nutritional value in different stages of growth and different cultivars in livestock feeding. Therefore, this experiment was conducted to investigate the effects of growth stages of some fodder corn cultivars on chemical compounds, parameters of gas production, and ruminal degradability, in four hybrid varieties of corn single-cross Simon, single-cross Valbum, single-cross corn BC 678. and single-cross N.S 770 maize variety was designed and carried out.
Material and Methods: Four varieties of fodder corn were planted in a uniform field with similar crop management in the farm of Behdis Protein Nasr Company, Behshahr, Mazandaran province, Iran, with an area of about one hectare for each variety, and after the operation, it was planted in two stages (August 2 and 24 August 2022) harvesting and laboratory operations were carried out in the Animal Nutrition Laboratory of the Animal Science Department of Sari University of Agricultural Sciences and Natural Resources (SANRU). In this research, four fodder corn cultivars were used in a completely randomized design in 4 treatments and 4 replications and two harvesting stages. Chemical compounds including dry and organic matter, crude ash, NDF and ADF, crude protein, crude fat and non-fibrous carbohydrates were determined. Also, the potential of gas production, digestibility, metaboliseble energy, and volatile fatty acids were assied with in vito method. In addition, determining rumen degradability and effective parameters of dry matter, crude protein, and neutral detergent fiber in rumen incubation at 0, 2, 4, 6, 12, 24, 36, 48, 72 and 96 hours were performed with in situ method using 3 rumen fistulated Zel sheep.
Resuls: Chemical compounds were affected by cultivar and harvest time. In two stages of harvest, the amount of crude protein and percentage of dry matter was significantly higher in singlecross NS770 cultivar and fat, insoluble fiber in acid detergent, and insoluble fiber in neutral detergent in singlecross BC678 cultivar. The effect of corn variety on the parameters of gas production at harvest times was different. In the first and second harvests, the rate of gas production and gas production in 96 hours, digestibility of organic matter, metabolizable energy and the concentration of short chain fatty acids were higher in singlecross NS770 variety. There was a significant difference in the gas production capacity of Single-Cross-Simon and Single-Cross NS770 cultivars in the first and second stages of harvesting. The gas production rate constant in the second stage of harvest was different between the treatments and it was higher in single-cross BC678 and single-cross NS770 than single-cross-Simon and single-cross-Valbum varieties. The percentage of organic matter digestibility was different between the treatments in the first and second harvest, and in the first harvest, the organic matter digestibility was higher in Single-Cross-Simon and Single-Cross NS770, and in the second harvest, Single-Cross-Simon had the highest amount of digestibility. The concentration of SCFAs was also significantly different between the treatments in the first and second harvest, its concentration was the highest in Single-Cross-Simon in the first and second harvest. Degradability of dry matter, crude protein and insoluble fiber in neutral detergent, fast degradable, slow degradable, potentially degradable, and effective degradability fractions were higher in singlecross NS770 silage at 2, 5 and 8% passge rates. The results of the gas test and determination of degradability showed that in the first harvest, the variety Single Cross NS770 had gas production capacity, constant rate of gas production and digestibility of organic matter and parameters of degradability of dry matter, crude protein and insoluble fibers in neutral detergent and higher effective degradability.
Conclusion: The test results showed that chemical compounds were affected by cultivar and harvest time. In two stages of harvest, the amount of crude protein and percentage of dry matter was significantly higher in singlecross NS770 cultivar and fat, insoluble fiber in acid detergent, and insoluble fiber in neutral detergent in singlecross BC678 cultivar. The results of the gas test and determination of degradability showed that in the first harvest, the variety Single Cross NS770 had gas production capacity, constant rate of gas production and digestibility of organic matter and a, b, and a + b, Kd as parameters of degradability of dry matter, crude protein and insoluble fibers in neutral detergent and higher effective degradability |