Effects of close-up dietary energy content and rumen-protected lysine and methionine fed pre- and postpartum on performance and health of Holstein cows.

This experiment was conducted to determine the effects of feeding rumen-protected Met (RPM; KESSENT M, Kemin Industries Inc., Des Moines, IA) and rumen-protected Lys (RPL; LysiGEM, Kemin Industries Inc., Des Moines, IA) prepartum at the same AA-to-ME ratio (3.21 g/Mcal of Lys and 1.21 g/Mcal of Met) with different concentrations of NEL on the performance of dairy cows. Sixty-two multiparous Holstein cows were assigned to 1 of 3 dietary treatments in a randomized, complete block design. Prepartum (-21 d to expected calving), cows were fed a controlled-energy (CE) diet (wheat straw based diet, 1.45 NEL[2.33 ME] Mcal/kg of DM] with RPL and RPM (CEAA; 0.15% RPL and 0.09% RPM of dietary DMI), CE diet without RPL and RPM (control; CENAA), or high-energy (HE) diet (corn silage-based diet, 1.71 NEL[2.70 ME], Mcal/kg of DM] with RPL and RPM (HEAA; RPL 0.22% and RPM 0.12% of dietary DMI). Postpartum, cows received the same lactation TMR (1.73 NEL[2.71 ME] Mcal/kg of DM) without RPL and RPM (CENAA, n = 19) or with RPL and RPM (CEAA, n = 21; and HEAA, n = 21; 0.38% RPL and 0.15% RPM of dietary DMI) until 70 DIM. Cows were milked twice daily, and milk samples were taken once a week from d 2 to 70 DIM. Milk yield and DMI were recorded daily. Blood samples were taken on -7 ± 4.7, 28 ± 1.6, and 70 ± 2.1 DIM. Two treatment contrasts (CENAA vs. CEAA and CEAA vs. HEAA) were compared. Cows in HEAA had higher ECM (50.5 ± 1.77 kg/d) and tended to have greater fat yield (2.04 ± 0.09 kg/d) and BCS loss (-0.71 ± 0.14) during wk 1 to 4 of lactation than cows in CEAA (45.7 kg/d, 1.82 kg/d, and -0.36, respectively). Cows in CEAA tended to have a higher protein proportion in milk (3.43% ± 0.07%) than cows in CENAA (3.26% ± 0.07%) and cows in HEAA (3.24% ± 0.07%) during wk 1 to 4 of lactation. Cows in CEAA had higher milk protein proportion (2.89% ± 0.05%) than cows in CENAA (2.72% ± 0.05%) during wk 5 to 10. Plasma Met concentrations prepartum were greater for cows in CEAA (24.7 ± 1.65 µM) than cows in CENAA (19.8 ± 1.65 µM). Cows in CEAA had higher plasma Lys (81.1 ± 3.35 µM) and Met (39.5 ± 2.04 µM) concentrations postpartum than cows in CENAA (71.5 ± 3.35 µM and 19.5 ± 2.04 µM, respectively). In conclusion, feeding a HE diet may have negatively affected the cows' body composition compared with cows fed a CE diet when both diets were formulated at 3.21 g/Mcal of Lys and 1.21 g/Mcal of Met, whereas, feeding RPL and RPM prepartum improved cows' performance compared with cows that were not fed RPL and RPM.