Abstract:The transition from experimentally induced poor nutritional conditions to feeding was studied with 69 eightmonth-old female reindeer (Rangifer tarandus tarandus). During a pre-experimental period, all reindeer were fed a simulated winter diet with 80% lichens Cladina spp. and 20% Vaccinum myrtillus shrubs and Salix spp. leaves (lichen diet) ad lib. The reindeer were divided into five groups. A control group (group C) was fed the lichen diet ad lib. throughout the experiment. Four groups were fed half of that ration for eight days and were then totally deprived of feed for one day (restriction period). During the following 34 days (feeding period) the groups were re-fed the lichen diet (group L), fed pelleted reindeer feed combined with either lichen (group PL) or grass silage (group PS), or fed silage with a gradually increasing addition of pellets (group SP). Weekly measurements of blood samples and body weighr showed that the control group remained clinically healthy and had stable blood plasma concentrations of protein, urea, glucose and insulin throughout the experiment, but they lost weight. At slaughter, before and after the restriction period, all animals had lost rumen-free body weight, but the reindeer fed a restricted amount of feed lost more than the control group. Also the plasma metabolites were affected by the restricted feeding, with increased concentrations of urea and decreased concentrations of glucose. Group L responded immediately to the ad lib. feeding with blood metabolite levels rapidly approaching those of group C. The body weight developments were similar in groups L and C. Although the feed rations were increased gradually, diarrhoea occurred in some animals belonging to groups PL and PS within the first week of the feeding period. All reindeer recovered, after antibiotic treatment of the worst affected animals. The PL and PS groups, which had high contents of metabolisable energy and crude protein in their diets, showed increased concenttations of plasma protein, urea and insulin. At the end of the feeding period, these groups had increased their body and carcass weights and gained fat, whereas reindeer fed the lichen diet had lost weight. Severe health problems (malnutrition and so-called wet belly) occurred in group SP during the first weeks of feeding and led to loss of animals, and consequently the SP group was excluded from the remainder of rhe experiment. The general conclusion is that the lichen diet did not cause any digestive problems, but resulted in a continuous decline in body weight and small or deficient fat reserves. After the initial diarrhoea, feeding with diets comprising pellets from the start resulted in improved condition, expressed as increased body weight, fat gain and higher concentrations of plasma protein, urea and insulin in relation to the control group. The diet initially based on grass in the form of silage of the given quality seemed insufficient as feed to reindeer calves in a poor nutritional state.

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 (Rangifer tarandus tarandus). All animals were initially fed a simulated winter diet based on lichens (lichen diet). A control group, continuously offered the lichen diet ad libitum, was compared to four groups of reindeer that were first restrictively fed (half the ad libitum 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 ad libitum 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 “wet belly” 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.

Abstract in Swedish / Sammandrag:

Vomfunktionen hos ren (Rangifer tarandus tarandus) efter begränsat födointag och påföljande utfodring Ett försök utfördes med syfte att ta reda på hur olika utfodringsstrategier påverkar vomfunktionerna hos ren (Rangifer t. tarandus) efter en period med lågt näringsintag. Vommens anpassning till olika dieter studerades hos 44 åtta månader gamla honkalvar Alla renarna gavs initialt en simulerad vinterdiet baserad på lav (lavdiet). En kontrollgrupp, som fick äta fritt av lavdieten under hela försöket, jämfördes med fyra grupper renar...

No abstract