Document Type : Research Paper
Authors
1 Department of Animal and Poultry Nutrition, Faculty of Animal Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
2 Dept. of Animal and Poultry nutrition, Faculty of Animal Science, Gorgan University of Agricultural Science and Natural Resources, Gorgan,Iran
Abstract
Objective: The aim of this study was to investigate the effects of replacing corn silage with sorghum silage on digestibility, production performance, blood parameters and feeding behaviors of Holstein dairy cows, which the forage sorghum varieties used were equivalent to corn in terms of yield under the best conditions.
Research method: For this purpose, sorghum silage of the Speedfeed variety was replaced with corn silage of the Single Cross 704 variety at ratios of zero (control), 33, 66 and 100%. Eight lactating cows with an average milk production of 34.5 kg per day were assigned in a Latin square experimental design with 4 treatments and 8 replications (repeated in 4 21-day periods) which was carried out in Semnan province, Shahrood county, Meighan village in the Koohpayeh dairy complex.
Findings: In this study, the results showed that there was no significant difference in dry matter intake between the treatments; However, all levels of substitution except for protein, which had digestibility equal to corn silage, decreased digestibility in dry matter intake, organic matter, fat, and NDF (P<0.05). Although milk production in the control treatment (containing 100% corn silage) was significantly higher than in the other treatments (P<0.05), there was no significant difference in milk production efficiency (kg of corrected milk produced per kg of dry matter intake) between the groups receiving the experimental diets. Milk fat percentage and fat to protein ratio were significantly higher in the treatment containing 100% sorghum silage than in the other treatments (P<0.05). In this study, the use of speed-feed sorghum silage significantly increased the amount of beneficial unsaturated fatty acids (P<0.05). Also, the highest eating and rumination time was related to the control treatment (containing 100% corn silage) and the lowest time was related to the 100% sorghum silage treatment (P<0.05). Since the more chewing and rumination activity, the less rest time is left for the animal, it seems that the level of comfort was higher in the treatments consuming sorghum silage.
Conclusion: The results of the study showed that sorghum silage can be fed to lactating Holstein cows as a complete alternative to corn silage without adverse effects on animal performance, but with positive effects on milk unsaturated fatty acids. This forage can be an excellent choice for dairy farms in arid and desert areas where corn cultivation is difficult due to water shortages. On the other hand, the cost of producing sorghum is significantly lower than corn.
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