نوع مقاله : مقاله پژوهشی
نویسندگان
گروه علوم دامی، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران، کرج، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
This study investigated the effects of glucose precursors (propylene glycol and glycerol) combined with two protein sources corn gluten and meat meal on newly calved Holstein cows in order to evaluate the individual and interactive effects of different glucose precursors and branched-chain amino acids on performance. A total of 42 multiparous Holstein cows, from 3 to 35 days postpartum, were utilized in a 2×3 factorial design with six treatments and seven replicates per treatment. The experimental diets consisted of a basal ration supplemented with 300 g of glucose precursors in three ratios of propylene glycol to glycerol (75:25, 50:50, and 25:75) as the first factor, and 600 g of protein source as the second factor. Daily feed intake and milk production were recorded, and milk, feed, and feces samples were collected at regular intervals. Results showed that the inclusion of glucose precursors, in combination with different amino acid sources, had no significant effect on daily dry matter intake, feed efficiency, or negative energy balance. While the interaction between treatments did not significantly affect daily milk yield, a significant difference was observed between glucose precursor treatments (p < 0.05). No significant differences were detected in fat-corrected milk (3.5%), milk fat content, or other milk components. The increased milk yield in cows fed propylene glycol may be attributed to its role in enhancing dietary energy density, promoting greater ruminal propionate production, and subsequently increasing glucose availability in cows experiencing negative energy balance. Nutrient digestibility and feed intake were unaffected by the treatments.
کلیدواژهها [English]
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