1- Department of Animal Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
2- Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
3- Dept. of Animal Sciences Research, Agricultural and Natural Resources Research and Education Center of Gorgan, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
4- Dept. of Biotechnology Research Department, Animal Science Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
2- Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
3- Dept. of Animal Sciences Research, Agricultural and Natural Resources Research and Education Center of Gorgan, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
4- Dept. of Biotechnology Research Department, Animal Science Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Abstract: (23 Views)
Background: The rapid increase in population and the continuously rising demand for meat and milk in Iran have led to significant development in ruminant livestock production. Nevertheless, the productivity of ruminants is highly dependent on feed availability and quality. Throughout the year, feed quantity and quality are often limited due to escalating costs, which directly affect the animals’ productive performance. The rising prices of conventional feed ingredients used in ration formulation necessitate that animal science specialists search for alternative feed resources that are less competitive with human food, readily available, and cost-effective. Since feed constitutes the most expensive component in rearing dairy calves, conducting research to determine an optimal dietary ration in terms of both animal performance and economic efficiency is essential for improving livestock production in the country. With technological advancements and new processing methods for converting and refining feed materials, many conventional livestock feed resources, including corn, wheat, and barley, have become competitive with human food sources. To address this challenge, efficient utilization of agricultural by-products and residues as ruminant feed is crucial for enhancing livestock production. One of these agricultural by-products is corn germ meal (CGM), which is produced during the extraction of corn germ through dry or wet milling processes for human-consumed corn oil. Corn germ meal is typically palatable and rich in highly digestible amino acids, making it a potential protein and energy substitute for meeting the nutritional requirements of ruminants. Additionally, due to its high hemicellulose content, CGM exhibits favorable pelleting properties and good hydration characteristics. Therefore, this study was conducted to evaluate the effects of replacing soybean meal (SBM) with corn germ meal in the diet on performance, digestibility, diarrhea incidence, blood metabolites, and skeletal growth parameters of Holstein dairy calves.
Materials and Methods: Eighteen newborn female Holstein calves were selected for this study. Immediately after birth, each calf’s umbilicus was disinfected using povidone-iodine, and their body weights were recorded. Subsequently, the calves were transferred to individual pens. During the first hours of life, colostrum equivalent to 10% of body weight was administered to each calf via bottle feeding. At seven days of age, the calves were randomly assigned to three dietary treatments, each consisting of six replicates. The experimental period lasted for 60 days. The treatments were as follows: Treatment 1 (Control): starter diet without CGM; Treatment 2: 5% of SBM replaced with CGM; Treatment 3: 10% of SBM replaced with CGM. To evaluate growth performance, calves were weighed every 15 days. Daily feed intake and feed refusals were recorded. Skeletal growth parameters were measured on day 50 of the experimental period. For digestibility analysis, feed, refusal, and fecal samples were collected from each calf over a five-day period from days 56 to 60. The samples were pooled, and a 100-gram subsample was taken for each calf, oven-dried at 64°C for 48 hours, and ground using a 1-mm sieve mill. The chemical composition of feed, refusal, and fecal samples, including neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein, and ash, was analyzed using standard analytical methods. Apparent nutrient digestibility was determined based on these analyses. Fecal scoring was performed through direct sampling from the rectum. Scores were assigned on a 1-to-5 scale: 1-firm and well-formed; 2-soft; 3-loose and watery; 4-watery with some blood; 5-watery with blood and mucus. Blood samples were collected from the jugular vein on day 60 into EDTA tubes as anticoagulants. Plasma was separated by centrifugation at 3000 rpm for 10 minutes and stored at −20°C until analysis. Plasma samples were analyzed for cholesterol, triglycerides, glucose, urea, albumin, globulin, total protein, and lipoproteins (LDL, HDL, VLDL) using commercial kits and a spectrophotometer.
Results: The results indicated that replacing SBM with CGM in the diet did not significantly affect body weight on days 15, 30, 45, or 60. Total body weight and average daily gain were also unaffected by the dietary treatments throughout the experimental period. Weekly feed intake, daily dry matter intake, and feed conversion ratio did not differ significantly due to the inclusion of CGM. Apparent digestibility of nutrients showed that organic matter, crude protein, and neutral detergent fiber digestibility were influenced by CGM supplementation, whereas other digestibility parameters were unaffected. Fecal scoring analysis revealed no significant differences in diarrhea incidence among the dietary treatments. However, certain blood parameters were affected; calves fed CGM exhibited significantly higher plasma triglyceride and urea concentrations compared to the control group. Nevertheless, skeletal growth parameters, including body length, withers height, and hip height, were not influenced by dietary replacement of SBM with CGM.
Conclusion: The findings of this study demonstrate that CGM can be incorporated up to 5% in the diet of dairy calves without adversely affecting growth performance, feed intake, nutrient digestibility, fecal consistency, skeletal growth, or most blood metabolites. Corn germ meal can therefore serve as an effective alternative to soybean meal in the diets of young Holstein calves, offering a cost-effective and nutritionally adequate feed option.
Materials and Methods: Eighteen newborn female Holstein calves were selected for this study. Immediately after birth, each calf’s umbilicus was disinfected using povidone-iodine, and their body weights were recorded. Subsequently, the calves were transferred to individual pens. During the first hours of life, colostrum equivalent to 10% of body weight was administered to each calf via bottle feeding. At seven days of age, the calves were randomly assigned to three dietary treatments, each consisting of six replicates. The experimental period lasted for 60 days. The treatments were as follows: Treatment 1 (Control): starter diet without CGM; Treatment 2: 5% of SBM replaced with CGM; Treatment 3: 10% of SBM replaced with CGM. To evaluate growth performance, calves were weighed every 15 days. Daily feed intake and feed refusals were recorded. Skeletal growth parameters were measured on day 50 of the experimental period. For digestibility analysis, feed, refusal, and fecal samples were collected from each calf over a five-day period from days 56 to 60. The samples were pooled, and a 100-gram subsample was taken for each calf, oven-dried at 64°C for 48 hours, and ground using a 1-mm sieve mill. The chemical composition of feed, refusal, and fecal samples, including neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein, and ash, was analyzed using standard analytical methods. Apparent nutrient digestibility was determined based on these analyses. Fecal scoring was performed through direct sampling from the rectum. Scores were assigned on a 1-to-5 scale: 1-firm and well-formed; 2-soft; 3-loose and watery; 4-watery with some blood; 5-watery with blood and mucus. Blood samples were collected from the jugular vein on day 60 into EDTA tubes as anticoagulants. Plasma was separated by centrifugation at 3000 rpm for 10 minutes and stored at −20°C until analysis. Plasma samples were analyzed for cholesterol, triglycerides, glucose, urea, albumin, globulin, total protein, and lipoproteins (LDL, HDL, VLDL) using commercial kits and a spectrophotometer.
Results: The results indicated that replacing SBM with CGM in the diet did not significantly affect body weight on days 15, 30, 45, or 60. Total body weight and average daily gain were also unaffected by the dietary treatments throughout the experimental period. Weekly feed intake, daily dry matter intake, and feed conversion ratio did not differ significantly due to the inclusion of CGM. Apparent digestibility of nutrients showed that organic matter, crude protein, and neutral detergent fiber digestibility were influenced by CGM supplementation, whereas other digestibility parameters were unaffected. Fecal scoring analysis revealed no significant differences in diarrhea incidence among the dietary treatments. However, certain blood parameters were affected; calves fed CGM exhibited significantly higher plasma triglyceride and urea concentrations compared to the control group. Nevertheless, skeletal growth parameters, including body length, withers height, and hip height, were not influenced by dietary replacement of SBM with CGM.
Conclusion: The findings of this study demonstrate that CGM can be incorporated up to 5% in the diet of dairy calves without adversely affecting growth performance, feed intake, nutrient digestibility, fecal consistency, skeletal growth, or most blood metabolites. Corn germ meal can therefore serve as an effective alternative to soybean meal in the diets of young Holstein calves, offering a cost-effective and nutritionally adequate feed option.
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