Effects of Supplementing Rumen-Protected Methionine and Lysine on Milk Performance and Oxidative Status of Dairy Ewes.

Alexandros Mavrommatis,Christina Mitsiopoulou,Eleni Tsiplakou,Marica Simoni,Paraskevi Kariampa,Federico Righi,Christos Christodoulou

doi:10.3390/antiox10050654

Alexandros Mavrommatis, Christina Mitsiopoulou + Show 5 more

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https://doi.org/10.3390/antiox10050654

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Abstract

There is limited information on the impact of dietary supplementation with separate rumen-protected (RP) amino acids (AA), or with their combination, on ewes’ oxidative status. Sixty ewes were divided into five groups; C: basal diet (control); M: basal diet + 6 g/ewe RP methionine; L: basal diet + 5 g/ewe RP lysine; LML: basal diet + 6 g methionine and 5 g lysine/ewe; and HML: basal diet + 12 g methionine + 5 g lysine/ewe. Milk’s fat content increased in RP-AA fed ewes, while that of protein in M and L only. In blood plasma, the malondialdehyde (MDA) content was reduced in the M, LML, and HML compared to C-fed ewes. An increase in glutathione transferase activity in the blood plasma of the M and LML compared to the C and HML-fed ewes were found. In milk, lower values of the ferric reducing ability of plasma (FRAP) in the LML and HML-fed ewes and of 2,2′-Azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) in LML only, were found. Lysine increased milk’s FRAP values and MDA content. Both L and HML diets increased milk’s protein carbonyls content. Methionine improves the organism’s oxidative status, without adversely affecting milk’s oxidative stability. Lysine dietary inclusion affects negatively the oxidative stability of milk.

Highlights

Proteins and amino acids (AA) constitute a historical scientific issue in ruminant nutrition that counts more than 100 years [1]
Considering the aforementioned, this study aimed to investigate the effect of dietary supplementation with RP methionine or lysine, as well as with a combination of these AAs in two different proportions, on (a) milk yield, chemical composition, fatty acid profile, (b) GSH-Px, Glutathione reductase (GR), GST, catalase (CAT), and superoxide dismutase (SOD), activities in blood plasma and SOD, GR and lactoperoxidase (LPO) activities in milk and c) total antioxidant capacity and oxidative stress indicators [MDA and protein carbonyls (PCs)] in both blood plasma and milk of early lactating ewes
Milk fat content was significantly increased (p < 0.001) in rumen-protected amino acids (RP-AA) fed ewes, with the highest increase being reported in the higher AA supplementation level (HML) group (Table 2)

Summary

Introduction

Proteins and amino acids (AA) constitute a historical scientific issue in ruminant nutrition that counts more than 100 years [1]. AAs such as methionine are involved in several cells’ metabolic pathways including that of energy [5] since are principal generators of one-carbon compounds [6]. For this reason, AAs can improve energy supply [7] and affect milk performance, chemical composition, and fatty acids (FA) profile [3]. Methionine and lysine are widely known as the first limiting AAs for milk protein synthesis in dairy ruminants as they constitute building blocks for caseins synthesis [7,9].

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