The Liver Functionality Index: A Measure of Transition-cow Health
The intricacies of transition-cow nutrition and its role in lactation success may be made a bit easier with the Liver Functionality Index (LFI).
Developed via a collaborative effort between Italian researchers and a team at the University of Illinois, the LFI is a composite index based on changes in plasma concentrations of biomarkers associated with liver plasma protein synthesis (albumin), lipoprotein synthesis (cholesterol), and heme catabolism (bilirubin).
In a study published in the Journal of Dairy Science, the researchers used the LFI to assess whether supplementing close-up cows with either rumen-protected methionine or choline could have a positive effect on post-calving heath and performance.
From 21 days before calving until 30 days after, 40 multiparous Holstein cows were randomly assigned to either the methionine or choline group. All cows received the same close-up ration. The methionine group was supplemented with the amino acid at an adjusted 0.08% of dry matter of diet. Choline was fed at 60 g/cow/day.
Liver and blood samples were harvested four times throughout the study period and assessed for biomarker levels. Based on this data, cows were assigned to low LFI and high LFI groups, regardless of supplementation treatment.
Among the results:
- High LFI cows had higher close-up and lactation dry-matter intake (DMI); milk yield, milk fat yield, and milk protein yield, compared to low LFI cows.
- Around the time of calving, low LFI cows had lower plasma cholesterol and albumin, but greater bilirubin concentrations.
- Plasma haptoglobin concentration was lower in high LFI cows, but plasma paraoxonase, hepatic total, and reduced hepatic glutathione concentrations were greater.
- Overall essential amino acid status did not differ with LFI status.
- Overall concentrations of nonessential amino acids; total amino acids; and total sulfur-containing compounds was greater in high LFI cows.
- Feeding supplemental methionine resulted in more cows classified as high LFI, compared to the cows supplemented with choline.
Developing the LFI helped the research team evaluate the impact of both supplements on fresh-cow performance, oxidative stress status, and plasma amino acid profiles. They determined that rumen-protected methionine was the more beneficial supplement.
Aside from the supplement evaluation, they also noted that low-versus-high LFI pre-calving could be an indicator of cows at greater risk of developing health problems after calving. A low LFI is indicative of a pronounced inflammatory response and less-favorable amino acid profile, which could lead to more challenges in transition.
In contrast, high LFI cows had a lower incidence of health complications, better lactation performance, and more favorable biomarker and plasma amino acid profiles, indicating a better pre-calving immunometabolic status.
Thus, the potential exists for the LFI to be used as a transition-cow health monitoring tool to assess pre-calving immune and inflammation status, as well as metabolic profiles, and perform nutritional interventions accordingly.