Metabolic and endocrine responses to short-term nutrient imbalances in the feed ration of mid-lactation dairy cows

Short-term imbalances of dietary nutrients occur during natural fluctuations in roughage quality (e.g. on pasture) or temporal shortages supplementary feed components. In contrast to a deficiency, macronutrients (i.e. carbohydrates, proteins, lipids) beyond the adequate supply with other may, for instance, alter milk composition, increase BW result greater excretion nitrogen. Especially dairy cows moderate performance, mid- late lactation, extensive farming systems may be exposed imbalanced rations. A better understanding metabolic and endocrine responses depending macronutrient help precisely cows. The present study investigated short-term different levels concentrates formulated particularly provide one major source (carbohydrates, proteins lipids). Based parity number, lactational stage, yield BW, nine mid-lactating (211 ± 19 days milk) were grouped into three blocks animals each. Concentrates (aminogenic: rich CP nitrogen sources; glucogenic: high content carbohydrates glucogenic precursors; lipogenic: lipid content) fed addition hay factorial arrangement at increasing from 2.5 7.5 kg/d 9 d. Milk yield, intake recorded daily. Blood sampled every 3 d end each concentrate level. fat, protein, lactose urea contents determined. blood, concentrations various metabolites, factors enzyme activities glucose, non-esterified fatty acids (NEFAs), β-hydroxybutyrate, urea, cholesterol, triglycerides, insulin, glucagon, aspartate aminotransferase (ASAT), gamma-glutamyltransferase (GGT) glutamate dehydrogenase activity (GLDH)) measured. composition not affected by type level concentrates. Feed increased amounts aminogenic lipogenic compared concentrate. plasma elevated lesser extent treatment treatment. Glucose treatments, whereas insulin glucagon increased, NEFA decreased only Activities ASAT, GGT GLDH as well total antioxidant capacity diets. conclusion, immediate observed due changes. Particularly, surplus via diet stimulated secretion.