Effects of rumen-protected lysine and histidine on milk production and energy and nitrogen utilization in diets containing hydrolyzed feather meal fed to lactating Jersey cows

摘要

Hydrolyzed feather meal (HFM) is high in crude protein,most of which bypasses rumen degradation whenfed to lactating dairy cows, allowing direct supply ofAA to the small intestine. Compared with other feedsthat are high in bypass protein, such as blood meal orheat-treated soybean meal, HFM is low in His and Lys.The objectives of this study were to determine the effectsof supplementing rumen-protected (RP) Lys andHis individually or in combination in a diet containing5% HFM on milk production and composition aswell as energy and N partitioning. Twelve multiparousJersey cows (mean ± SD: 91 ± 18 d in milk) were usedin a triplicated 4 × 4 Latin square with 4 periods of28 d (24-d adaptation and 4-d collection). Throughoutthe experiment, all cows were fed the same TMR, withHFM included at 5% of diet DM. Cows were groupedby dry matter intake and milk yield, and cows withina group were randomly assigned to 1 of 4 treatments:no RP Lys or RP His; RP Lys only [70 g/d of Ajipro-L(24 g/d of digestible Lys), Ajinomoto Co. Inc., Tokyo,Japan]; RP His only [32 g/d of experimental product (7g/d of digestible His), Balchem Corp., New Hampton,NY]; or both RP Lys and His. Plasma Lys concentrationincreased when RP Lys was supplemented withoutRP His (77.7 vs. 66.0 ± 4.69 μM) but decreased whenRP Lys was supplemented with RP His (71.4 vs. 75.0± 4.69 μM). Plasma concentration of 3-methylhistidinedecreased with RP Lys (3.19 vs. 3.40 ± 0.31 μM). WithRP His, plasma concentration of His increased (21.8 vs.18.7 ± 2.95 μM). For milk production and milk composition,no effects of Lys were observed. SupplementingRP His increased milk yield (22.5 vs. 21.6 ± 2.04 kg/d)and tended to increase milk protein yield (0.801 vs.0.772 ± 0.051 kg/d). Across treatments, dry matterintake (18.5 ± 0.83 kg/d) and energy supply (32.2 ±2.24 Mcal of net energy for lactation) were not different.Supplementing RP His did not affect N utilization;however, supplementing RP Lys increased N balance(25 vs. 16 ± 9 g/d). The lack of production responses toRP Lys suggests that Lys was not limiting or that theincrease in Lys supply was not large enough to causean increase in milk protein yield. However, increased Nbalance and decreased 3-methylhistidine with RP Lyssuggest that increased Lys supply increased proteinaccretion and decreased protein mobilization. Furthermore,His may be a limiting AA in diets containingHFM.