Abstract
The peripartum (or transition) period is the most-critical phase in the productive life of lactating dairy cows and optimal supply of trace minerals through more bioavailable forms could minimize the negative effects associated with this phase. Twenty Holstein cows received a common prepartal diet and postpartal diet. Both diets were partially supplemented with an inorganic (INO) mix of Zn, Mn, and Cu to supply 35, 45, and 6 ppm, respectively, of the diet dry matter (DM). Cows were assigned to treatments in a randomized completed block design, receiving an daily oral bolus with INO or organic trace minerals (AAC) Zn, Mn, Cu, and Co to achieve 75, 65, 11, and 1 ppm supplemental, respectively, in the diet DM. Liver tissue and blood samples were collected throughout the experiment. The lower glutamic-oxaloacetic transaminase concentration after 15 days in milk in AAC cows indicate lower hepatic cell damage. The concentration of cholesterol and albumin increased, while IL-6 decreased over time in AAC cows compared with INO indicating a lower degree of inflammation and better liver function. Although the acute-phase protein ceruloplasmin tended to be lower in AAC cows and corresponded with the reduction in the inflammatory status, the tendency for greater serum amyloid A concentration in AAC indicated an inconsistent response on acute-phase proteins. Oxygen radical absorbance capacity increased over time in AAC cows. Furthermore, the concentrations of nitric oxide, nitrite, nitrate, and the ferric reducing ability of plasma decreased with AAC indicating a lower oxidative stress status. The expression of IL10 and ALB in liver tissue was greater overall in AAC cows reinforcing the anti-inflammatory response detected in plasma. The greater overall expression of PCK1 in AAC cows indicated a greater gluconeogenic capacity, and partly explained the greater milk production response over time. Overall, feeding organic trace minerals as complexed with amino acids during the transition period improved liver function and decreased inflammation and oxidative stress.
Highlights
The transition period is the most-critical phase in the productive life of high-producing dairy cows and it is characterized by decreased liver function and increased inflammation and oxidative stress [1, 2]
In order to address this hypothesis we evaluated blood biomarkers and liver mRNA expression of genes related with liver function, inflammation, oxidative stress and metabolism
The Fisher’s analysis of the 5 cows in AAC and 1 cow in INO revealed that treatment had no impact (P = 0.10) on the numbers of cows that had to be removed after parturition due to the onset of a clinical disease [13]
Summary
The transition period is the most-critical phase in the productive life of high-producing dairy cows and it is characterized by decreased liver function and increased inflammation and oxidative stress [1, 2]. The liver of early-lactating dairy cows that is under physiological stress is likely to have its functions more impaired due to inflammation. Oxidative stress results when reactive forms of oxygen are produced faster than they can be neutralized by antioxidant physiologic mechanisms in tissues and blood. Increased production of free radicals and reactive oxygen species coupled with decreased antioxidant defense mechanisms leads to damage of macromolecules and deregulation of normal metabolism during oxidative stress [4, 5]. Evidence indicates that oxidative stress plays a key role in several pathological conditions connected with animal production, reproduction and welfare [6]
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