Rumen function in reindeer (<em>Rangifer tarandus tarandus</em>) after sub-maintenance feed intake and subsequent feeding

Abstract

<p>The aim of this experiment was to ascertain how different feeding strategies affect the rumen function of reindeer after nutritional deprivation. Rumen adaptation to various diets, after restricted feeding, was studied in 44 eight-month-old semi-domesticated female reindeer (<em>Rangifer tarandus tarandus</em>). All animals were initially fed a simulated winter diet based on lichens (lichen diet). A control group, continuously offered the lichen diet <em>ad libitum</em>, was compared to four groups of reindeer that were first restrictively fed (half the <em>ad libitum</em> ration) for eight days followed by one day without feed. The rumen content of restrictively fed animals had higher pH, lower dry matter content and volatile fatty acid (VFA) concentration, a changed composition of VFAs, and lower counts of bacteria compared to that of the control group. The effect was less dramatic than previously reported for reindeer starved for several days. On day 10, the four restrictively fed groups were introduced to different diets. One group was re-fed the lichen diet <em>ad libitum</em> and did not differ from the control group when the experiment ended after five weeks of feeding. Two groups were fed grain-based reindeer feed (pellets) combined with either lichens or grass silage, and one group was fed silage with a gradually increased addition of pellets. Diarrhoea and so called &ldquo;wet belly&rdquo; occurred initially in the three latter groups. After five weeks of feeding, the reindeer in the three pellet-fed groups had an altered composition of VFAs and higher counts of protozoa, and also tended to have higher total VFA concentration in the rumen, compared to the control animals and those re-fed the lichen diet. Only small changes were observed in the size of rumen papillae and these could be associated with energy intake. Protozoa decreased over time on the lichen diet. This study confirmed that rumen function was significantly affected by a relatively short period of restricted feed intake. The experiment also revealed a clear difference in rumen function between reindeer adapted to a lichen-based diet and those adjusted to basically grain-based diets. Bacteria that were utilising lichens were drastically reduced when the diet lacked lichens; consequently these bacteria may be regarded as a substrate-specific group.</p><p>Abstract in Swedish / Sammandrag:</p><p>Vomfunktionen hos ren (<em>Rangifer tarandus tarandus</em>) efter begr&auml;nsat f&ouml;dointag och p&aring;f&ouml;ljande utfodring Ett f&ouml;rs&ouml;k utf&ouml;rdes med syfte att ta reda p&aring; hur olika utfodringsstrategier p&aring;verkar vomfunktionerna hos ren (<em>Rangifer t. tarandus</em>) efter en period med l&aring;gt n&auml;ringsintag. Vommens anpassning till olika dieter studerades hos 44 &aring;tta m&aring;nader gamla honkalvar Alla renarna gavs initialt en simulerad vinterdiet baserad p&aring; lav (lavdiet). En kontrollgrupp, som fick &auml;ta fritt av lavdieten under hela f&ouml;rs&ouml;ket, j&auml;mf&ouml;rdes med fyra grupper renar...

The structure and functional profile of ruminal microbiota in young and adult reindeers (Rangifer tarandus) consuming natural winter-spring and summer-autumn seasonal diets

“…The bacteria with the maximal numbers of edges (concentrators) were found to belong to the class Bacteroidia (phylum Bacteroidetes) and classes Negativicutes and Clostridia (phylum Firmicutes). These taxa are evidently responsible for the largest part of the ruminal metabolism; primarily in the metabolism of complex carbohydrates, protein, monosaccharides, and organic acids, as these substances are the main components of their diets and are important intermediates in the metabolism of energy, as has been shown in our analysis of reindeer dietary composition and earlier data on the nutrition of reindeer ( Pulliainen, 1971 ; Nilsson et al, 2006 ; Mathiesen et al, 2006 ). It is safe to assume that these taxon-concentrators play a key role in the formation of the sustainable core of the ruminal microbiota in reindeer.…”

Reindeer Husbandry and Global Environmental Change

“…In a well-functioning reindeer rumen, the pH varies between 6 and 7 (Nilsson et al 2006). Grain-based feeds for reindeer contain easily digestible carbohydrates (primarily starch) that lower the rumen pH when fed in large amounts.…”