Tove H. Aagnes

Round baled grass silage as food for reindeer in winter

Round baled silage of mixed grasses was tested as emergency food for reindeer in winter. The silage was made of leaf rich regrowth of Phleum pratense, Agrostis tenuis and Poa spp. It contained 33-3% dry matter (DM), and 14.8 % crude protein, 24.5% cellulose and 26.7% hemicellulose on a DM basis. Palatability, food intake, digestion, rumen fermentation, body mass (BM), carcass weight and gastrointestinal (GI) anatomy were investigated. A group of adult female reindeer (n = 38), were taken from natural winter pasture and fed grass silage ad libitum. The majority (78%) of the animals were eating silage after two days and 95% of the animals ate silage after five days. Five reindeer calves were taken from natural winter pasture and fed lichens ad libitum for 14 days after which they were starved for two days before being offered silage adlibitum. The median daily DM food intake was 370 g (range 250-610 g) on the first day increasing to 810 g (range 530-1100 g) at days 16 to 20. Median apparent digestibility coefficient (DC) of DM was 64.3% (range 62.4-66.2%). The median in vitro DM digestibility (IVDMD) of the silage after 72 h of microbial digestion was 68.3 % (range 66.6-71.3 %) (Ws=30, n,=5, n2=4, P<0.01). Median ruminal VFA concentration and pH were 48.2 mM (range 38.4-52.5 mM) and 7.0 (range 6.95-7.17), respectively, in the reindeer calves (n=5). BM initially increased when the reindeer calves were fed silage, but stabilised after 11 days. The increased BM may have been due to an increased recticulo-rumen digesta load, which amounted to 19.6-23.7 % of BM (n=3). The carcass weight of the reindeer calves was 42.6-44.2% of the BM (n=3) after 47 days of silage feeding. The results indicate that although the round bale silage of mixed grasses of medium quality was highly palatable to reindeer it was apparantly of only limited value as an emergency food for the reindeer calves, as indicated by low DC of DM and low ruminal VFA concentration.

Food and snow intake, body mass and rumen function in reindeer fed lichen and subsequently starved for 4 days

Food and snow intake, body mass, rumen fluid volume, rumen fluid turnover time and ruminal dry matter content were examined in four female rumen fistulated reindeer which were first fed lichen ad libitum in 14 days and then starved for 4 days in March. When the animals were eating lichen median daily dry matter food intake was 15.7 g/kg (range 12.2-19.9 g/kg), while median daily snow intake only amounted to 0.6 g/kg (range 0-3.3 g/kg). The median body mass decreased from 67.5 kg (range 62.5-69.5 kg) to 63.5 kg (range 60.5-68.5 kg) during this period, and dropped further to 62.5 kg (range 57.5-66.0 kg) after four days of starvation. Rumen fluid volume and fluid turnover time were fairly constant in individual animals, but varied between animals fed lichen ad libitum. Neither of these parameters changed significantly (P>0.05), but ruminal dry matter decreased, while snow intake rose conspicuously in reponse to starvation. Thus, aside from the latter, which mitigate the reduction of total rumen volume, we have failed to expose any special adaptions aimed at the maintenance of ruminal integrity in starving reindeer.

The bacteriology of the small intestinal mucosa of free-living reindeer

Bacteria in close associaton with the intestinal mucosa are thought to protect the mucosa from pathogenic microorganisms. The pH of the small intestinal mucosa and the viable populations of aerobic and anaerobic bacteria associated with the proximal and distal jejunal mucosa, were measured in four free-living reindeer in winter. The anaerobic bacterial populations were characterized. The median pH of the mucosa of the duodenum was 6.6 (n=4) at point 0.2 m from the pyloric sphincter. The mucosal pH increased along the length of the intestine to 8.3 at 14 m and then decreased to 7.9 at 19.8 m from the pyloric sphincter. Examination by transmission electron microscopy and cultivation techniques failed to reveal any bacteria on the mucosa of the proximal jejunum in two of the animals. In two other reindeer the median anaerobic bacterial densities in the proximal jejunum ranged from 25-2500 cells/g mucosa. The median anaerobic bacterial populations in the distal jejunum ranged from 80 to 20000 bacteria/g mucosa (n=4). The anaerobic population of bacteria in the proximal jejunum was dominated by streptococci and unidentified gram positive rods. Bacteroidaceae, streptococci and unidentified gram positive rods were common in the distal jejunum. The low density and the species diversity of bacteria in the small intestine suggests that these microorganisms are inhibited by components in the natural winter diet of reindeer. Bacteria evidently play a minor role in protection of the mucosa of reindeer in winter.

Gross anatomy of the gastrointestinal tract in reindeer, free-living and fed baled timothy silage in summer and winter

The gross anatomy of the gastrointestinal (GI) tract was investigated in reindeer calves (Rangtfer tarandus tarandus), free-living and fed two different qualities of timothy silage in September 1992 (summer) and April 1993 (winter) and related to the body condition. At both seasons nine male reindeer calves were taken from a natural pasture. Three animals were slaughtered directly (NP reindeer), three offered first cut (FC) silage and three regrowth (RG) silage ad lib., for 46 days. The FC silage contained 27% leaves and 57.8% dry matter (DM) cell wall content (CWC) and the RG silage 89 % leaves, and 38.7% DM CWC. The reticulo-rumen (RR) digesta wet weight in the NP reindeer in summer was 6.7-7.7% of body mass (BM), compared to 25.1-32.8% and 9.6-12.9% of BM, respectively, in the animals fed FC and RG silage. In winter the RR digesta wet weight relative to BM in the NP reindeer and in the animals fed FC and RG silages were 9-5-11.5%, 25.4-33.3% and 10.4-18.3%, respectively. The distal fermentation chamber (DFC) digesta wet weight in the NP animals in summer was 0.48-0.80% of BM, compared to 0.77-1.26% and 0.57¬0.65% of BM, respectively, in the animals fed FC and RG silage. In winter the DFC digesta wet weight relative to BM in the animals fed FC and RG silage did not differ significantly from the summer values (P>0.05), while in the NP reindeer it was 1.0-1.2% of BM which is significantly greater than in summer (P<0.05). The differences in relative weight of the fermentation chambers between the animals fed FC and RG silage both summer and winter were not reflected in total BM, which was similar in all groups fed silage. This is explained by a significantly lower carcass weight in the animals fed FC silage compared to the animals fed RG silage. Thus, the GI-tract gross anatomy in the silage fed animals seem to be highly affected by the plant structure and composition, and not by the season.

Failure of cellulolysis in the rumen of reindeer fed timothy silage

Three male reindeer (Rangifer tarandus tarandus) calves were brought from mountain pastures in April and fed regrowth timothy (Phleum pratense) silage with 76% leaves and 24.0% dry matter (DM) ad libitum. The silage contained (on DM basis) 25.4% cellulose, 12.0% crude protein and 19-6% water soluble carbohydrates. After an initial period of 11 days the daily silage intake rose to almost similar values for all animals, but independently of food intake, body mass (BM) increased by as much as 13.3 kg for animal R3 during the first 21 days, compared to 4.4 kg and 2.8 kg for Rl and R2, respectively. At slaughter the wet weight of the rumen contents of animal R3 constituted 30.2% of the total BM, compared to 18.5% and 19.1% in animals Rl and R2, respectively. A reduced ability of the rumen micro-biota to ferment pure cellulose in vitro was observed in R3. The ruminal pH was 7.07 and the concentration of volatile fatty acids was only 50.0 mM in R3, indicating a low rate of fermentation. The initial rates of in vitro dry matter digestibility of timothy silage and standard hay were also affected by the rumen fermentation failure in animal R3. Depressed rumen cellulolysis, which may be related to natural periods of starvation prior to the feeding experiment, could have caused the low rate of fermentation and the large rumen size observed in this animal.

Digestive physiology of minke whales

Abstract The anatomy and principal function of the gastro-intestinal tract of minke whales were investigated. The stomach consists of four compartments, including an initial non-glandular forestomach followed by a glandular fundic chamber, a connecting chamber and a pyloric chamber. The length of the small intestine of minke whales is short, only four times body length, and the colon and caecum are poorly developed. the forestomach is small, containing between 5 and 80 1 of contents, with as much as 24.8% dry matter (DM). High population densities of anaerobic bacteria were found in the forestomach fluid, and adherent to the food particles. pH in the forestomach fluid ranged between 5.36 and 7.43, and the concentration of volatile fatty acids (VFAs) ranged between 49 and 486 mM. Based on these results we conclude that minke whales primarily utilize the prey they eat by microbial digestion. The contribution from VFAs to the daily energy requirements of minke whales seems to be of less importance than in ruminants. The multi-chambered stomach probably is an adaptation which increases passage time and, hence, microbial and enzymatic digestion. We suggest that the relatively small size of the stomach of minke whales, compared with that of ruminants, reflects their carnivorous diet, but does not neces-sarily indicate any reduced importance of the forestomach microbial digestion.