followed by a presentation by Professor Juan Loor of the University of Illinois titled “Methionine – Much more than a nutrient”. His deep dive into the metabolic benefits of supplemental methionine and the importance of a well-balanced Methionine:Lysine ratio over the need to supplemental choline gave the audience a lot of food for thought. With more research being conducted looking at the effects of balancing amino acids in dairy diets and feeding rumen protected products, the knowledge and understanding around this topic is quickly bringing more confidence to the commercial application of these strategies and the benefits they can bring to the UK dairy industry.
“Methionine – Much more than a nutrient”, Professor Juan Loor, University of Illinois
Methionine is well known to be the first limiting amino acid in milk protein production for the lactating cow, however it’s only really since the 2000s that the focus has shifted from milk production to include the transition cow and further parameters. Research has found that cows have a higher need for methionine during the transition period, and it should be fed at 2.3-2.4% of metabolisable protein (approximately 7-10 grams of digestible methionine) in a ratio to Lysine of 2.8 to 1. Paying close attention to this parameter during the transition phase and through peak lactation enables improvements in production, as well as animal health and impact on progeny.
Health benefits
Trial data shows that feeding a Met:Lys of 2.8:1 for 30 days pre calving and 60 days post calving not only increased energy corrected milk compared to the control treatment, but also enhanced innate immunity, as can be seen through an increase in activity of immune cells in the blood (neutrophil phagocytosis and oxidative burst), compared to the control group (Batistel et al. 2018). This increased neutrophil activity means the cow is better prepared to combat infection and so contributes to an overall improvement in health.
Inflammation and oxidative stress can occur during the transition period due to multifaceted causes, such as over- or under-conditioning, mastitis, retained placenta or acidosis. The metabolic stress triad (Figure 1) outlines how three key metabolic issues of oxidative stress,
Figure 1: Metabolic Stress Triad
inflammatory immune dysregulation and excessive lipid mobilisation feed into each other. Oxidative stress can develop through elevated levels of Non-Esterified Fatty Acids (NEFAs) from excessive lipid mobilization and an induced production of Reactive Oxygen Species (ROS) in immune cells due to inflammation. Likewise, inflammatory immune dysregulation is induced by oxidative stress and the increase in NEFAs and beta-hydroxybutyrate (BHB). The resultant lipid mobilisation occurs as both a direct cause of the inflammatory immune dysregulation as well as a subsequent reduction in dry matter intake (DMI). The release of these lipids can lead to a ketotic state with direct health and financial implications, as well as increased likelihood of displaced abomasum (Abuelo et al. 2019).
If unchecked, these metabolic actions will trigger and exacerbate each other, but they can be prevented through nutritional manipulation of energy supply and micronutrients. Glutathione is a powerful antioxidant that is synthesized in the body from the sulphur amino acids methionine or cysteine. Therefore, cows can benefit from an increased provision of methionine around calving to combat oxidative stress and reduce any subsequent effects on lipid mobilisation and immune dysregulation.
Progeny
As the uterus takes up 70% of the maternal supply of amino acids, it is essential that these are provided in sufficient quantities to support foetal development to its fullest. Cows fed methionine balanced diets in the transition phase had significantly higher wither heights than control cows, however this did not result in any difference in calving difficulties. Through the pre-weaning period, these heifer calves also had better growth rates compared to control calves when all fed the same milk replacer diet, despite no significant differences in feed intake (Alharthi et al., 2018). The pre-weaning period is a window that can program the physiology and performance for later life through mammary development (Geiger et al., 2017) and future milk yield (Soberon et al., 2012), so methionine balancing in the mother leading to taller and faster growing calves could influence future progeny performance as well. Innate immune cell activity (neutrophil phagocytosis) was elevated in calves from methionine balanced mothers, showing a priming of the immune system, along with higher levels of liver enzyme activity. Samples taken from the calves at birth showed that there was a difference between methionine and control group for the faecal metabolome and microbiome, which will influence the hindgut function of the calf (Elolimy et al., 2019).
Conclusion
Methionine not only acts as an essential amino acid contributing to milk protein production but has wider implications in the control of cow health and improved progeny production. Further understanding of the impact of methionine on the metabolic processes of the cow will help us to utilise this micronutrient in a much more efficient way.
References available on request from
holly.malins@
evonik.com FEED COMPOUNDER JANUARY/FEBRUARY 2020 PAGE 37
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