AUTHOR=Pérez-Ruchel Analía , Repetto José Luis , Cajarville Cecilia 

TITLE=Supplementation of high-quality fresh forage to lambs fed a total mixed ration increased in vitro ruminal fermentation and digestibility

JOURNAL=Frontiers in Animal Science

VOLUME=4

YEAR=2023

URL=https://www.frontiersin.org/journals/animal-science/articles/10.3389/fanim.2023.1032527

DOI=10.3389/fanim.2023.1032527

ISSN=2673-6225

ABSTRACT=<p>The supplementation of fresh alfalfa into the diet of growing lambs fed with decreasing levels of a total mixed ration (TMR) was studied for its effect on <italic>in vitro</italic> ruminal fermentation activity. Twenty-four catheterized lambs [25.2 ± 3.67 kg body weight (BW)] were assigned to one of the following treatments: “TMR100”—TMR <italic>ad libitum</italic>; “TMR75’” and “TMR50”—TMR at 0.75 and 0.50 of potential intake, respectively, supplemented with alfalfa; and ‘TMR0’—only alfalfa <italic>ad libitum</italic>. <italic>In vitro</italic> gas production kinetics and true digestibility (IVTD) were evaluated using the rumen liquid as inocula. Ruminal pH values and NH<sub>3</sub>-N and volatile fatty acid concentrations were studied at the same time as inocula extraction. As the amount of alfalfa in the diet increased—by decreasing the level of TMR—<italic>in vitro</italic> gas production, ruminal pH values, NH<sub>3</sub>-N concentrations, and acetic acid proportions linearly increased (<italic>p</italic> = 0.005, 0.008, 0.004, and 0.018, respectively). IVTD tended to linearly rise (<italic>p</italic> = 0.083) and the fermentation rate (<italic>p</italic> = 0.004) and propionic acid proportion (<italic>p</italic>&lt; 0.001) linearly decreased. We conclude that the increase in the level of fresh alfalfa resulting from the decrease in TMR levels in lambs’ diet positively impacted rumen fermentation activity and <italic>in vitro</italic> digestibility through the promotion of a suitable environment for ruminal microbiota.</p>