Evaluating the bioavailability of rumen protected methionine products and their effects on performance of dairy cows
Date
2021
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
Two experiments were conducted to evaluate the performance of KESSENT M (RPM-K; Kemin Industries, Des Moines, IA, USA) to commercially available products by examining plasma methionine response and effect on animal performance in Holstein dairy cows. ☐ For experiment 1, 10 multiparous Holstein cows 280 (± 73) days in milk (DIM) were used in a replicated 3×3 Latin square design with 7-day experimental periods. Treatments were administered at time of feeding three times daily and consisted of a control diet plus 12 g/d of one of three rumen protected methionine (RPM) products, either the newly developed product RPM-K or one of two existing products, RPM-S and RPM-M, with known differences in bioavailability. During days 5-7 of each period, blood samples were collected from jugular catheters at 2, 4, 6, and 8 h after the morning feeding, and underwent amino acid analysis. Plasma methionine data were analyzed using the full data set as well as theoretical data sets containing individual cow plasma samples pooled by day or period. We observed that plasma methionine was affected by treatment (P = 0.006) and time (P = 0.001). There were no differences between RPM-S and RPM-K (32.7 vs 33.0 µM, respectively; P = 0.79), and both were greater than RPM-M (30.1 µM; P ≤ 0.001). The time affect was due to reduced plasma methionine at 4 h (30.2 µM) than at the 2, 6, and 8 h sampling times (31.9-33.0 µM; P > 0.05). Using the theoretical pooled plasma samples, differences observed in the full model were maintained when samples were pooled by day, but only a trend for a difference among treatments was observed when samples were pooled by period. Bioavailability of RPM-K was similar to RPM-S and greater than RPM-M. Similar results would likely have been obtained had plasma samples been pooled by day for each cow in each period, but not if plasma samples had been pooled by period for each cow. ☐ For experiment 2, we utilized 24 multiparous and 6 primiparous Holstein cows 95 (± 20) and 71 (± 3) DIM, which were assigned treatments using a replicated 3 × 3 Latin square design with 21 day periods. Treatments consisted of a control diet deficient in metabolizable methionine (MP Met) by 17 g, or control diet plus 14 g/d one of two RPM products (RPM-K or RPM-S). Milk samples were collected on d 13-14 and 18-21 of each period. Plasma samples were collected at 2 and 6 hours after feeding on d 21 of each period and subjected to free amino acid analysis. Milk fat percentage of cows given RPM-S (3.73%) was not different from RPM-K (P = 0.32) and tended to be greater than Control (P = 0.0504). Milk fat yield was no different between RPM-K and RPM-S (both 1.48 kg/d; P = 0.78. There was no difference in milk protein percent between RPM-K and RPM-S (3.25%; P = 0.96), and both were greater than Control (3.22%; P = 0.02). Plasma free methionine as a percentage of total amino acids minus sulfur containing amino acids was no different between RPM-S and RPM-K (2.05 and 2.04, respectively; P = 0.87), and both were greater than Control (1.39; P < 0.0001). Both RPM-K and RPM-S demonstrated similar increases in milk fat and protein percent relative to the control. Plasma free methionine response to each supplement was similar, suggesting similar bioavailability. ☐ Our objective was to evaluate the efficacy of the recently developed rumen protected methionine product KESSENT M to currently marketed products. There are limited options when it comes to viable sources of rumen protected methionine from which dairies can choose from, and it may be beneficial to expand upon competitive products. The efficacy of products was determined by their impact on plasma methionine and production performance in response to RPM supplementation. Our previous work had found that KESSENT M had a high bioavailability, and it was hypothesized that it would yield a plasma methionine and production response competitive to marketed products.
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Keywords
KESSENT M, Plasma methionine response, Rumen protected methionine