Concurrent and carryover effects of feeding blends of protein and amino acids in high-protein diets with different concentrations of forage fiber to fresh cows. 1. Production and blood metabolites

Abstract

Because of low feed intake during the first weeks of lactation, dietary concentration of metabolizable protein (MP) must be elevated. We evaluated effects of providing additional rumen-undegradable protein (RUP) from a single source or a blend of protein and AA sources during the first 3 wk of lactation. We also evaluated whether replacing forage fiber (fNDF) or nonforage fiber with the blend affected responses. In a randomized block design, at approximately 2 wk prepartum, 40 primigravid (664 ± 44 kg of body weight) and 40 multigravid (797 ± 81 kg of body weight) Holsteins were blocked by calving date and fed a common diet (11.5% crude protein, CP). After calving to 25 d in milk (DIM), cows were fed 1 of 4 diets formulated to be (1) 20% deficient in metabolizable protein (MP) based on predicted milk production (17% CP, 24% fNDF), (2) adequate in MP using primarily RUP from soy to increase MP concentration (AMP; 20% CP, 24% fNDF), (3) adequate in MP using a blend of RUP and rumen-protected AA sources to increase MP concentration (Blend; 20% CP, 24% fNDF), or (4) similar to Blend but substituting fNDF with added RUP rather than nonforage neutral detergent fiber (Blend-fNDF; 20% CP, 19% fNDF). The blend was formulated to have a RUP supply with an AA profile similar to that of casein. A common diet (17% CP) was fed from 26 to 92 DIM, and milk production and composition were measured from 26 to 92 DIM, but individual dry matter intake (DMI) was measured only until 50 DIM. During the treatment period for both parities, AMP and Blend increased energy-corrected milk (ECM) yields compared with the diet deficient in MP based on predicted milk production (40.7 vs. 37.8 kg/d) and reduced concentrations of plasma 3-methyl-His (4.1 vs. 5.3 µmol/L) and growth hormone (9.0 vs. 11.9 ng/mL). Blend had greater DMI than AMP (17.4 vs. 16.1 kg/d), but ECM yields were similar. Blend had greater plasma Met (42.0 vs. 26.4 µmol/L) and altered metabolites associated with antioxidant production and methyl donation compared with AMP. Conversely, the concentration of total essential AA in plasma was less in Blend versus AMP (837 vs. 935 µmol/L). In multiparous cows, Blend-fNDF decreased DMI and ECM yield compared with Blend (19.2 vs. 20.1 kg/d of DMI, 45.3 vs. 51.1 kg/d of ECM), whereas primiparous cows showed the opposite response (15.3 vs. 14.6 kg/d of DMI, 32.9 vs. 31.4 kg/d of ECM). Greater DMI for multiparous cows fed Blend carried over from 26 to 50 DIM and was greater compared with AMP (23.1 vs. 21.2 kg /d) and . Blend also increased ECM yield compared with AMP (49.2 vs. 43.5 kg/d) and Blend-fNDF (45.4 kg/d) from 26 to 92 DIM. Few carryover effects of fresh cow treatments on production were found in primiparous cows. Overall, feeding blends of RUP and AA may improve the balance of AA for fresh cows fed high MP diets and improve concurrent and longer-term milk production in multiparous cows. However, with high MP diets, multiparous fresh cows require greater concentrations of fNDF than primiparous cows.

Effects of metabolizable protein concentration, amino acid profile, and fiber source on the messenger RNA expression of skeletal muscle in peripartum dairy cows

“…Greater ER stress is also associated with lipotoxicity (Han and Kaufman, 2016) and the high mobilization of lipid during early lactation could be responsible for increased ER stress. Total losses of EB lipid were similar (Tebbe and Weiss, 2021b), but milk fat synthesis was increased with greater MP concentrations (Tebbe and Weiss, 2021a) and may have partially alleviated lipotoxicity and reduced ER stress.…”

“…This indicated an increase in branched-chain AA oxidation and reduced FA oxidation in A-MP versus Blend. Increased BCAT1 and MUT may suggest an excess supply of branchedchain AA for A-MP, which was supported by the greater plasma concentrations of Ile and Val and numerically greater Leu for A-MP versus Blend (Tebbe and Weiss, 2021a). Increased fast-twitch glycolytic muscle fibers may also contribute to altered metabolism of the muscle.…”

“…More fast-twitch glycolytic fibers also suggests that a better AA supply increases glucose oxidation in muscle. This may spare FA and could partially explain greater milk fat yield and lower plasma glucose concentrations later into lactation for Blend versus A-MP (Tebbe and Weiss, 2021a).…”

“…Previously, our laboratory found decreased concentrations of plasma 3-methyl-His, a biomarker of skeletal muscle breakdown (Blum et al, 1985), and increased yields of milk fat and protein when feeding greater MP concentrations to or when improving the AA balance in early-postpartum cows (<25 DIM; Carder and Weiss, 2017;Tebbe and Weiss, 2021a). After treatments ended and when cows received a common diet, greater MP concentration and a better AA supply led to increased milk fat and protein concentrations from 21 to 90 DIM (Carder and Weiss, 2017) and increased yields of protein and fat in multiparous cows from 26 to 92 DIM Effects of metabolizable protein concentration, amino acid profile, and fiber source on the messenger RNA expression of skeletal muscle in peripartum dairy cows Alexander W. Tebbe, 1 * Juliette Hanson, 2 and William P. Weiss 1 † (Tebbe and Weiss, 2021a). Carryover effects suggested a link between skeletal muscle breakdown in the earlypostpartum period and longer-term milk production.…”

Alterations in Skeletal Muscle mRNA Abundance in Response to Ethyl-Cellulose Rumen-Protected Methionine during the Periparturient Period in Dairy Cows

“…Even though extensive research focus has been placed on reducing negative energy balance, less research has been conducted on the consequences of indispensable amino acid (AA) imbalances. Published data has highlighted that lactation performance was improved by feeding ethyl-cellulose rumen-protected methionine (RPM) [6], rumen-protected lysine [7], or AA balanced-diets [8] around parturition.…”