Stable isotopes to study sulfur amino acid utilization in broilers

Biological effects of iodine, selenium, sulfur citrates in broiler chickens

This study aimed at the assessment of the I, Se, S citrate effect on the organism of broiler chickens. Feeding of chickens of all groups was carried out by using standard balanced feeds – starter, grower, and finish with the use of group feeders placed at the appropriate height from the floor depending on the poultry height. For the chickens of experimental groups, I, Se, S citrate was added to drinking water daily during the 48th day. To the drinking water of chickens of experimental groups different amounts of the citrate solution were added I (200 mg/L), Se (50 mg/L), S (300 mg/L), prepared by the nanotechnology method. Chickens of the II group received the lowest dose of I, Se, S at the rate of 5 μg I/L, 1.25 μg Se/L, 7.5 μg S/L of drinking water, and for poultry of other experimental groups, it was increased by 2 (III), 4 (IV), 6 (V) and 8 (VI) times compared to II group. Coccidiostat "Kokcisan 12%" (KRKA, Slovenia) was added to the starter and grower feed at the stages of its manufacture in quantities of 0.5 kg/t of feed. Coccidiostat was not added to the final feed. During the 48-day technological period, the clinical condition of the poultry was monitored daily by forage and motor activity, safety, and every 7 days – for growth intensity with the individual determination of body weight on a laboratory scale. The investigation of the blood was carried out from the 35th or 48th day during the growing, period and also investigation of the internal organs – liver, heart, spleen, stomach, thymus, and bursa of Fabricius. The increase of cholesterol, triacylglycerols, and albumin in the blood of II, III, and VI chicken groups was established on the 35th day of the experiment, and the reduction of creatinine in III and VI groups. By that time, the effect of highest dose of I, Se, S caused a decrease in the T3 concentration in the blood of chickens in the VI group compared to the I and II groups. In particular, in the blood of chickens of IV, V and VI groups compared to the I, II, III group under these conditions there was a significant increase in the content of urea, Ca, P, cholesterol, as well as albumin – only in IV group on the 48th day. Triacylglycerols’ content increased in the blood serum of chickens in III and IV groups compared to the II and V groups, but in V group – decreased compared to the III, IV groups. The increase in liver, thymus, and heart mass in the II and V chicken groups was noticed and their decrease in the VI group was revealed compared with the control group. Reliable lower coefficients of the body mass of chickens of III and VI groups may indicate a less notable stimulating biological effect of I, Se, S citrate in these doses on liver development than on the whole organism. The addition of I, Se, S citrate to broiler chickens during the period of growing revealed the difference in their biological action in the presence and absence of the Kokcisan 12% in a mixed fodder. A more notable stimulating effect of low dose of I, Se, S citrate on the growth and development on the chickens' organism was established during the withdrawal of coccidiostatics from their diet. The effect may be due to its inhibitory influence on the biological activity of these elements in the first 35 days of growing. In the final period of chicken growing and withdrawal of ionophore Kokcisan from the diet more noticeable changes were revealed in the studied parameters.

Threonine incorporation in tissues of growing broiler chickens using L-[15 N] threonine

Most amino acid requirement trials appear for whole-body responses, but there is little information concerning amino acid incorporation in individual tissues, which may vary according to the age. L-[¹⁵ N] threonine was used to evaluate its incorporation rate and distribution among broiler tissues in different ages. Seventy-two male broiler chickens were distributed into three different phases: starter (4 to 9 days old), grower (18 to 23 days old) and finisher phase (32 to 37 days old). L-[¹⁵ N] threonine was added on balanced diets, and birds were fed for five days in each phase. Enriched samples of breast muscle, feathers, liver, jejunum and plasma were collected at 0, 6, 12, 24, 48, 72, 96 and 120 hr after fed birds with the tracer in each phase. In the tissues were analysed dry matter, nitrogen and stable nitrogen. The ¹⁵ N isotope abundance according to the time was fitted into exponential or linear equations using a same intercept. The ratio of the steepness or slope coefficients was determined to compare the L-[¹⁵ N] threonine incorporation according to the age. In addition, L-[¹⁵ N] threonine mass balances were performed to assess the L-[¹⁵ N] threonine distribution among the evaluated tissues. Except for feathers, the L-[¹⁵ N] threonine incorporation rate decreased with ageing. Taking into account the L-[¹⁵ N] threonine distribution in the tissues, only in the jejunum was not observed an increase as the broiler grew. The L-[¹⁵ N] incorporation varied in each tissue and according to the age of the broiler chickens. These outcomes could be useful to comprehend changes in amino acid requirements tissue-specific according to age.

Utilization of Methionine Sources for Growth and Met+Cys Deposition in Broilers

Simple Summary

Methionine (Met) is the first limiting amino acid in broiler feeds and for balancing dietary Met and methionine+cysteine (Met+Cys) levels. DL-2-hydroxy-4-methylthio butanoic acid (HMTBA) and DL-methionine (DLM) are typical feed additives. The relative bioavailability value (RBV) describes the nutritional value of HMTBA relative to DLM and is important for adequate, precise, and cost-effective broiler nutrition. The current broiler feeding trial revealed an average RBV of 63% compared to DLM and the inclusion of an internal standard into the experimental design allowed for validation of the methodological approach. Evaluation of the utilization of supplemental Met sources for Met+Cys deposition in body protein provided further evidence for a higher efficiency and, thus, nutritional value of DLM over HMTBA.

Abstract

Knowledge about the nutritional value of methionine sources is highly important for their appropriate application in terms of animal and economic performance. Therefore, a broiler feeding trial was conducted to determine the relative bioavailability value (RBV) of DL-2-hydroxy-4-methylthio butanoic acid (HMTBA) compared to DL-methionine (DLM). DLM diluted to 65% purity (DLM65) served as the internal standard, with a known RBV of 65%. A total of 1920 d-old male broilers were used in the three-phase feeding trial comprising 16 treatments including a basal, Met+Cys-deficient diet and 5 graded DLM, HMTBA, or DLM65 levels. Growth performance and carcass quality data were subjected to multi-exponential regression analysis. Increasing levels of any Met source significantly improved all performance parameters compared to the negative control (p < 0.05). Across all performance parameters, the RBV of HMTBA was 63% and that of DLM65 was 58%. All RBV estimates of HMTBA and DLM65 were significantly lower than 88% (p < 0.05). Cumulative efficiency of DLM for Met+Cys deposition in body protein was higher than that of HMBTA at any dose, confirming the determined RBV. Using DLM65 as an internal marker allowed for validation of the methodology.