Department of animal science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashad, Iran
Introduction: Breeding quality calves with a desirable genetic potential is one of the important criteria in dairy herds. In recent years, particular attention had been paid to calf breeding, especially to the composition of starter. Early weaning and encouraging the calf to consume solid feed reduces the incidence of various diseases, including diarrhea. It was important to transfer the calf from the non-ruminant state to the active ruminant state as soon as possible for the improved health and growth of the dairy calf. To transition from a liquid feed to a solid feed containing grains and forage, it was necessary to address several challenges. These included adapting the digestive system, enabling ruminal fermentation, and improving the digestion of nutrients through the intestine. Grains, which are full of carbohydrates, were considered to be the main source of energy in ruminants, leading to an excess in the growth of rumen epithelium. Corn grain was a major source of energy in ruminants as a digestible source. In comparison with other grains, the starch available in the corn grains was digested more slowly in the rumen. To use it to its full potential, its bio-availability should be increased so that a higher level of energy was released from the starch.
Material and Methods: This experiment was performed in the Astan Qods Razavi dairy farm, Mashhad, Iran. Forty Holstein calves, consisting of 20 male and 20 female, with an average birth weight of 42.4 Kg (± 4.3) were used from birth to 70 days. Calves were birth and immediately separated from their dam and weighting, then they were transferring to individual pen. On the third day, the calves were randomly assigned to one of two treatments. The experimental treatment included: 1) low starch, and 2) high starch. All calves received colostrum for 3 d and then whole milk at 15% of body weight in the two equal meals, morning (5:00 A.M) and evening (15:00 P.M), until weaning. Calves’ accesses to water and starter ad libitum and starter was mixed with 5% of alfalfa hay chopped (% of DM). Composition of starter did not change throughout the experiment. Starter intake was record daily. Body weight determine every two weeks until the end of experiment. Fecal consistence was scored daily. Blood sample was harvested from jugular vein for collection of blood serum. Blood metabolites including: glucose, cholesterol, triglyceride, albumin, total protein, ALT, AST, and urea were analyzed. Skeletal development was measured and recorded using special instruments on the 3, 56 and 70 days. Data were analyzed using SAS version 9.4 as a randomized completely design with GLM method and tendencies were reported at 0.05<P<0.10. Least square means for each treatment are reported in the tables and were separated using Tukeys test.
Results and Discussion: The results of this study showed that the use of the different level of starch had no significant effect on the starter feed intake, average daily gain, feed efficiency, fecal score and skeletal growth parameters of calves. Serum concentration of total protein, triglyceride, albumin, cholesterol, urea. ALT, and AST not affected by experimental treatments. ADG was not influenced by treatment in experiment. Our results are consistent with the observations of Zhang et al. (2010). There were no treatment effects on the blood parameters measured over time, which aligns with the findings of Soltani et al. (2020).The treatments did not affect fecal scores, as reported in the studies by Soltani et al. (2020). There were no significant differences in the initial, daily change, and final parameters, which is similar to the findings of Soltani et al. (2020). Additionally, starter intake, total dry matter intake (DMI), and weaning body weight (BW) were not affected by the experimental diets. This result is consistent with the observations of Lesmeister and Heinrichs (2004).
Conclusion: The result of this study showed that different levels of starch had no marked effects on body weight, daily feed intake, feed efficiency, fecal score, skeletal growth and blood metabolites.
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