Effect of N-acetyl-l-methionine supplementation on lactation performance and plasma variables in mid-lactating dairy cows

Abstract

The objective of current study was to investigate the effect of N-acetyl-l-methionine (NALM) supplementation on lactation performance and plasma variables in mid-lactating dairy cows. Forty-eight multiparous cows were blocked into 12 groups based on parity, days in milk, and milk production and were randomly assigned to 1 of the 4 treatments: 0, 15, 30, or 60 g/d of NALM per cow to supplement the basal diet. The experiment was conducted over a 13-wk period, with the first week as adaptation. The yields of milk, fat-corrected milk, and milk lactose were increased quadratically, and energy-corrected milk yield tended to increase with increased NALM supplementation in a quadratic manner. The dry matter intake, milk protein yield, milk fat yield, contents of milk composition (protein, fat, lactose, total solids, and milk urea nitrogen), feed efficiency, and body weight change were not affected by NALM supplementation. In addition, plasma methionine concentration was increased quadratically, and proline, total nonessential AA, and total AA concentrations were significantly higher in the 30 g/d group compared with that of the control group. However, other AA and total essential AA concentrations were not affected with supplementation of NALM. Adding NALM increased concentrations of total protein and globulin in plasma, but decreased plasma urea nitrogen concentration in a quadratic manner. Meanwhile, plasma malonaldehyde concentration decreased linearly as doses of NALM addition increased. Our results suggested that the supplementation of NALM improved milk yield and protein synthesis in the liver, and lowered lipid peroxidation in mid-lactating dairy cows.

Lactational performance of dairy cows in response to supplementing N-acetyl-l-methionine as source of rumen-protected methionine

“…N-Acetyl-l-Met supplementation increased milk fat synthesis and feed efficiency in early-lactation (53 ± 10 DIM, SD) dairy cows (Fagundes et al, 2018). Liang et al (2019) observed greater milk yield with NALM supplementation in mid-lactation dairy cows (167 ± 13 DIM); however, no effects were observed on feed efficiency and milk fat synthesis. Although rumen-protected Met (RPM) supplementation in dairy cow diets have been extensively evaluated (Schwab, 1996;Schwab and Broderick, 2017), we are still lacking studies evaluating the long-term efficacy of RPM on production performance of lactating dairy cows.…”

“…Despite inconsistent milk yield responses, NALM supplementation increased feed efficiency in previous studies. Liang et al (2019) observed a tendency for greater feed efficiency, expressed as FCM/DMI, for cows supplemented with 30 g of NALM. Similarly, Fa-gundes et al ( 2018) and Osorio et al (2013) reported greater 3.5% FCM/DMI and ECM/DMI for cows supplemented with RPM sources.…”

“…Fagundes et al (2018) reported similar effects on milk yield with NALM supplementation in diets adequate or deficient in MP; however, 3.5% FCM and ECM yields tended to increase with 30 g of NALM, regardless of the dietary MP status (Fagundes et al, 2018). Liang et al (2019) reported a quadratic effect on yields of milk, 3.5% FCM, and ECM, as greater 2018) and Liang et al (2019). Although the differences in starch and CP concentration may not affect production parameters because diets were balanced for MP, different standards for diet formulation (CNCPS vs. National Research Council) may have resulted in differences in estimation of MP adequacy.…”

“…The most common and expected responses with RPM supplementation in dairy cows are the increases in yield and concentration of milk protein (Rulquin et al, 1993;Vyas and Erdman, 2009;Patton, 2010). However, effects on milk protein synthesis were not consistent in NALM studies (Fagundes et al, 2018;Liang et al, 2019) or in studies supplementing other sources of RPM (Kröber et al, 2001;Younge et al, 2001;Davidson et al, 2008). Fagundes et al (2018) reported increased milk fat synthesis with NALM, and the effects were attributed to the role of Met in onecarbon metabolism, resulting in greater FA delivery and synthesis in the mammary gland.…”

Predicting Daily Dry Matter Intake Using Feed Intake of First Two Hours after Feeding in Mid and Late Lactation Dairy Cows with Fed Ration Three Times Per Day

“…Researchers conducting dairy cow experiments can easily and accurately obtain the feed intake data of dairy cows when the cows are fixed in one position [20][21][22]. However, with the modern construction of dairy farms and the emphasis on the animal welfare, almost all commercial dairy farms nowadays are free-stall barn system, in which all cows are fed in a moving and eating freely cowshed [23].…”