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Functional amino acids supplemented to dairy cows regulate key metabolic pathways to improve health, growth, development, and reproduction, in addition to lactation. More specifically, functional aspects of methionine include, among others, cell signaling impacting protein and energy metabolism or the modulation of immune and oxidative stress responses. Another important aspect is the regulation of gene expression. Indeed, as a methyl donor, methionine may act on DNA methylation, which is one biological mechanism of epigenetics consisting in adding methyl groups to nucleic bases. Gene transcription is typically repressed by methylation, inducing changes in subsequent metabolic pathways.
The transition period in dairy – a metabolic challenge for the lactating cow and the future calf
The transition period includes the last 3 weeks before calving (close-up period) and the first 3 to 4 weeks after calving (fresh period). For the cow, the main challenge is to get enough energy to support the increasing milk production despite a low intake. This imbalance between nutrient requirement and supply may trigger a negative energy balance (NEB), leading to fat mobilization from the tissues. This fat is usually transported as non-esterified fatty acids (NEFA) to the liver, which further produce ketone bodies (e.g., ß-hydroxy butyrate; BHB). Although ketone bodies partially fulfill the energy requirements of the different organs such as the mammary gland, an accumulation of NEFA and BHB has deleterious impacts on liver functions and subsequent metabolic functions leading to increased oxidative stress and inflammation. Therefore, preventing NEB in this sensitive phase is key to maximize the performance of the fresh cow.
For the future calf, late gestation is the period when fetal growth is the most important. Adequate nutrient supply is then essential to ensure an optimal health and growth of the offspring. This is of utmost importance for heifers considering that recent studies showed that preweaning growth is positively correlated with first-lactation yield.
Methionine supply during the transition period
Evonik conducted a study with University of Illinois (USA) to assess the effect of additional metabolizable methionine on health and performance of transition cows and their offspring, assuming that:
- Increased availability of methionine in transition cows will impact, among others, the energy and oxidative metabolism, reducing the occurrence of NEB and oxidative stress, leading to better health and performance.
- Increased availability of methionine in the fetal stage will favor DNA methylation that will modify the metabolic functions of the calves after birth.
Four weeks before expected parturition and until 60 days in milk, 2 balanced groups of 30 Holstein cows were fed the same corn silage-based diet without or with Mepron® (0.09% prepartum, 0.10% postpartum). Upon birth, all calves followed a common feeding management program until weaning (56 d). In addition to measurements of intake and lactation performance, blood samples were collected frequently on cows to analyze indicators of NEB and oxidative stress. Body weight of calves were measured at birth and every week until weaning. Weekly fecal and respiratory scores, daily rectal temperature and starter intake were also recorded.
Higher performance of lactating cows with Mepron® thanks to lower negative energy balance and oxidative stress
Plasma concentration in glutathione, a powerful antioxidant originating from methionine, was increased with Mepron® whereas circulating NEFA level was lower in cows receiving additional methionine (Figure 1). These results confirm the beneficial effect of this amino acid on health and energy metabolism of the cow. It is also known that high NEFA concentrations suppress DMI. In the present study, cows that received additional methionine had 10% greater DMI throughout the transition period.
These beneficial effects of methionine on health, energy metabolism and intake must have contributed to the greater performance of cows. Milk production within the first 4 weeks of lactation was 4.1 kg greater with Mepron®, and at peak lactation, the difference was even 4.4 kg/d. Energy-corrected milk was also higher with Mepron® (Figure 2) since it generated greater yields of fat, protein, and lactose. In addition, Mepron®-supplemented cows responded with significantly increased milk protein concentration.
Maternal Mepron® supplementation enhances growth performance of calves
On average, calves from Mepron®-supplemented cows were 3.1 kg heavier during the preweaning phase than calves from cows fed the basal diet only (Table 1). This enhanced growth rate was confirmed by the higher average daily gain (ADG; +50 g/d) of calves. It must be noted that improved performance were not related to a modification in starter intake, supporting the fact that differences in performance are related to metabolic changes following in-utero supply of methionine. Increased methionine availability during fetal stage also improved health status of calves, as indicated by the tendency for lower fecal score.
In conclusion, supplementing Mepron® during the transition phase benefits both the health and performance of transition cows and their offspring.
Visit the Halchemix website for more information: https://www.halchemix.ca/dairy
