Effect of feeding hydrolyzed feather meal and rumen-protected lysine on milk protein and energy utilization in late-lactation Jersey cows.

Hydrolyzed feather meal (HFM) is a feed that is high in rumen undegradable protein; however, it is low in Lys compared with other high rumen undegradable protein sources. Additionally, processing methods differ by facility, which affects AA composition and protein digestibility. The objective of this study was to use lactating dairy cows to determine the effects of feeding 2 sources of HFM that differed by the amount of blood they contained and also to study the effects of supplementing rumen-protected (RP) Lys when these sources of HFM are fed. In this study, 12 multiparous Jersey cows were enrolled in a triplicated 4 × 4 Latin square with 4 periods 28 d in length. Cows were fed 2 total mixed rations that differed by source of HFM. The HFM was included at 4.5% of the diet dry matter, and one source was produced with the addition of poultry blood. Cows were randomly assigned to 1 of 4 treatment sequences. Treatments were as follows: HFM without added blood and no RP-Lys, HFM with added blood and no RP-Lys, HFM without blood and with RP-Lys (22 g of digestible Lys), and HFM with added blood and RP-Lys. The source of HFM containing blood tended to increase dry matter intake (18.3 vs. 17.3 ± 0.72 kg/d), and increased milk yield (20.5 vs. 18.4 ± 1.31 kg/d) and protein yield (0.788 vs. 0.694 ± 0.040 kg/d). The inclusion of RP-Lys did not affect milk or protein yield. In cows fed HFM containing blood, plasma concentration of Lys (82.1 vs. 70.8 ± 4.06 μM) and His (27.8 vs. 17.9 ± 3.15 μM) was higher. The addition of RP-Lys had no effect on the concentration of either plasma Lys or His. Gross energy intake tended to increase for HFM containing more blood (81.4 vs. 77.3 ± 3.29 Mcal/d); however, no difference was observed for intake of digestible energy (52.0 ± 2.20 Mcal/d) or metabolizable energy (46.4 ± 2.02 Mcal/d). Similar to dry matter intake, N intake increased with the inclusion of HFM containing blood, but crude protein digestibility decreased (61.6 vs. 66.0%). Results of this study highlight that source of HFM can be a factor that affects milk production and that this in part is due to differences in the profile of AA. Additionally, the observation that plasma His and milk protein increased with the consumption of HFM containing more blood suggests that His may have played a role in increasing milk and milk protein yield.