Abstract #T177

# T177
Effects of rumen protected lysine and histidine on performance and energy and nitrogen partitioning in high-hydrolyzed-feather-meal diets fed to Jersey cows.
D. L. Morris*1, P. J. Kononoff1, 1Department of Animal Science, University of Nebraska–Lincoln, Lincoln, NE.

The objectives of this study were to determine the effects of supplementing rumen protected (RP) Lys and His individually or in combination in a diet containing hydrolyzed feather meal (HFM) on milk production and composition and energy and N partitioning in dairy cows. Multiparous Jersey cows (n = 12; 91 ± 18 d in milk) were used in a triplicated 4 × 4 Latin square with 4 periods of 28 d (24-d adaptation and 4-d collection). Throughout the experiment, all cows were fed the same TMR (17.1% crude protein, 1.64 Mcal/kg of net energy of lactation) with HFM inclusion at 5% of diet DM. Cows were grouped by dry matter intake and milk yield and cows within a group were randomly assigned to one of 4 treatments: no RP Lys or RP His; RP Lys only [70 g/d of Ajipro-L (approximately 23 g/d of digestible Lys); Ajinomoto Co., Inc., Tokyo, Japan]; RP His only [32 g/d of experimental product (approximately 8 g/d of digestible His); Balchem Corp., New Hampton, NY]; or both RP Lys and His. Data were analyzed with a model that included the fixed effect of Lys, His, and 2-way interaction and the random effect of period, square, cow within square, and error. For milk production and components, no Lys effect or interactions were observed (P > 0.14). Supplementing RP His increased (P < 0.10) milk yield (22.5 vs. 21.6 ± 2.04 kg/d) and milk protein yield (0.801 vs. 0.772 ± 0.051 kg/d). Across treatments, dry matter intake (18.5 ± 0.83 kg/d), energy supply (48.8 ± 2.21 Mcal of metabolizable energy/d) and N partitioning were not observed to differ (P > 0.10). With RP His, plasma concentration of His increased (P = 0.06; 21.8 vs. 18.7 ± 2.95 µM). Plasma Lys concentration increased when RP Lys was supplemented without RP His (77.7 vs. 66.0 ± 4.69 µM), but decreased when RP Lys was supplemented with RP His (71.4 vs. 75.0 ± 4.69 µM; interaction P = 0.04). Our results suggest that His may be a potentially limiting AA in high-HFM diets and that supplementation of RP His may increase milk and milk protein production. No response to RP Lys suggesting that Lys was not limiting.

Key Words: lysine, histidine, hydrolyzed feather meal