JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND Maataloustieteellinen Aikakauskirja 127 Voi. S4: 127-135, 1982 Comparison of grass silage utilization by reindeer and sheep. 2. Rumen fermentation and rumen microbiota LIISA SYRJÄLÄ-QVIST Department of Animal Husbandry, University of Helsinki 00710 Helsinki 71, Finland Abstract. The criteria used in comparing the utilization of grass silage by reindeer and sheep were rumen pH, ammonia, volatile fatty acids (VFA) and microbes. Rumen samples were taken before feeding, and 2'/i and 5/i hours after the beginning of feeding. Rumen fermentation was lower in the reindeer than in the sheep and differed less between the three sampling times. In the reindeer/the pH of the rumen fluidaveraged 6.94 and in the sheep 6.61. The average amounts of NHj—N were 17.0 and 24.2 mg/100 ml rumen fluid and those of total VFA 8.46 and 10.90 mmoles/100 ml rumen fluid, respectively. The proportion of acetic acid in the VFA in the reindeer was 75.3 molar % and in the sheep 66.0 molar %, the corresponding values for propionic acid being 18.5 and 22.0 molar % and for butytic acid 4.2 and 8.8 molar %. The number of rumen ciliates in the reindeer averaged 87/mm' rumen contents and in the sheep 314/ mm 3 . The numbers of bacteria were 16.0 X IOVmm3 , respectively. The proportion of the total microbe mass in the reindeer rumen contents was 1.8 % and in the sheep 2.4 %, The proportions of bacteria in this mass were 87 % and 70 %, respectively. The differences between the reindeer and sheep in the rumen fermentation results and in the numbers of rumen microbiota were nearly all statistically significant (PCO.OOI - PC0.05). Introduction The principal products of rumen fermentation are ammonia and volatile fatty acids (VFA). Both amounts of these products and the rumen microbial synthesis have been used as criteria, when describing feed utilization by ruminants. Considerable research has thus been devoted to the dietary factors which affect their amounts and to the proportions of the individual fatty acids. The domestic ruminant used most often in these experiments has been the sheep. Being only a semi-domestic animal the reindeer has less frequently been chosen for this kind of physiological study. The main purpose of the present study was to investigate grass silage as a feed for reindeer and to compare its utilization between reindeer and sheep. https://www.c-info.fi/en/info/?token=tDaUa67pEM5vybPg.BlWiyQMmW6CzNbl3TsoBDg.-pndkQcbylrH1ayYpM5aEb4h9NwY23i-nHfLYhoC9gziX4pb_dlbvR3Wy8AAA8aUr8SFW4YG4CDD1Clnug30aV7HTIhbBKNNpU5w2omxHnrMiMfVgAde6DS9hFA22LCkP5_Q8UswDMZ0Lu4RKHwWIzQgxZc98V2tTNuMSldid8KlipUBRmnDBWardw 128 This paper deals with the rumen fermentation and rumen microbes in reindeer and sheep on silage diets. The palatability and nutritive value of silage have been compared between the two animals in another paper (SYRJÄLÄ-QVIST 1982). Experimental procedures The experiment was performed with three adult male reindeer and three adult Finsheep rams, using a 3 x 3 Latin square design. Grass silage was the only feed. The experimental procedures are explained in more detail in the earlier paper (SYRJÄLÄ-QVIST 1982). Rumen samples were taken three times in each of the last two days of every experimental period. They were obtained from the sheep through a permanent rumen fistula and from the reindeer through the mouth with soft silicone tube, 1.5 cm in diameter. The sampling times were: before feeding in the morning, and 2 1/2 and 5 1/2 hours after the beginning of feeding. For pH, ammonia and VFA the sampling and the treatments and analyses of the samples were the same as described by SYRJÄLÄ (1972), and for the rumen microbiota they were as described by SYRJÄLÄ et ai. (1973, 1976). The pH was measured, and the ammonia and rumen microbes determined on each sample, altogether 48 samples from the reindeer and 54 from the sheep. For the determination of volatile fatty acids, the samples taken at the same sampling time on the two days were mixed together. The silages were prepared from grass at three different stages of growth. As the chemical composition and the quality of the different silages were the same (Table 1, SYRJÄLÄ-QVIST 1982), the rumen fermentation results are expressed as the average values for all the silages. Results and discussion Rumen fermentation pH. At every sampling time the pH values of the rumen contents of the reindeer were significantly higher than those of the sheep (P < 0.05 or P < 0.001), the average values for the reindeer at the different times being 7.08, 6.86 and 6.88, as opposed to 6.77, 6.50 and 6.56 for the sheep (Fig. 1, Table 2). The individual differences were larger in the reindeer than in the sheep. A reason for the higher pH values for the reindeer may be the different sampling technique. Being taken through the mouth the rumen samples from the reindeer, may possibly have been contamined by saliva, although the tube was rinsed with rumen contents before collection. In an experiment where the reindeer were rumen-fistulated, the pH of the rumen contents on silage feeding was 6.35—6.70 and on lichen feeding 6.15 6.20 (SYRJÄLÄ 1978). The pH values for the sheep in the present 129 Table 1. The chemical composition and quality of the silage. Variation between the growth stages Mean Dry matter, % % of dry matter: Ash 25.9 25.2-26.8 11.2 10.4-12.6 14.2-16.3 8.7-11.1 5.2-6.1 Crude protein True protein Crude fat 15.0 9.8 5.6 N-free extrack Crude fibre 40.4 39.5-41.5 27.1-28.5 5.8-10.4 27.8 Sugars as glucose % of total N; 7.9 Ammonia N Soluble N 4,1 3.8—4.4 51 51 PH 3.82 3.80-3.85 Table 2. pH, ammonia nitrogen and volatile fatty acids in the rumen fluid of reindeer and sheep. The values are the averages of the different sampling times. Reindeer Sheep PH 6.94 17.0 6.61 NHj-N, mg/100 ml 24.2 Total VFA, mmoles/100 ml 8.46 10.90 Acetic acid, molar % 75.3 66.0 Propionic acid 18.5 22.0 Butyric acid 4.2 8.8 Isovaleric acid 1.6 2.3 Valeric acid 0.4 0.9 Ratio acetic; propionic ” acetic: butyric ” propionic: butyric 4.1 3.0 18.9 7.7 4.6 2.5 experiment were at the same level as in another experiment with animals on silage feeding (SYRJÄLÄ 1972). Ammonia. The ammonia in the rumen fluid of the reindeer and sheep was at the same level in the samples taken before feeding (Fig. 1, Table 2), but after feeding it rose more sharply in the sheep, the increase being significant (P < 0.01). The average ammonia values for the reindeer at the different sampling times, 16.8, 18.9 and 15.2 NHj-N mg/100 ml of rumen fluid, were quite near the values in the earlier silage experiment, where they were 14.7—16.4 mg/100 ml (SYRJÄLÄ 1978), but higher than those recorded on lichen feeding, which were 5.6—6.8 mg/100 ml. The ammonia values for the sheep correspond to those in the earlier study (SYRJÄLÄ 1972). The fact that the values for the reindeer differed so little between the sampling times can mainly be explained by their eating habits. The reindeer ate their silage rations very slowly during the whole day, whereas the sheep finished them in about half an hour. Similar eating habits have been observed 130 in an earlier experiment with reindeer on silage feeding (SYRJÄLÄ and HEIKKILÄ 1975) and also when silage was fed in practical reindeer husbandry (KURKELA 1976). The amount of silage consumed each day by the reindeer in this experi- ment was about half of that eaten by the sheep, 3.6 kg versus 7.1 kg (SYRJÄLÄ-QVIST 1982). The total water intake by the reindeer was 5 kg/kg DM eaten, and by the sheep 3 kg. Volatile fatty acids. The total amount of VFA was not determined separately, but was taken as being the sum of the amounts of acetic, Fig. 1. pH, NH 3-N and VFA in the rumen fluid of reindeer and sheep. 131 propionic, butyric, isovaleric and valeric acids, which were determined by gas chromatographic analyses and expressed as mmoles/100 ml of rumen fluid (see SYRJÄLÄ 1972). The total VFA in the rumen fluid of the reindeer was significantly lower (PCO.OOI - P<0.05) at every sampling time than in that of the sheep (Fig. 1, Table 2). The values for the reindeer at the different sampling times were 7.54, 8.85 and 9.00 mmol/100 ml, and did not differ significantly from each other (P>0.05), whereas the values for the sheep differed significantly (P<0.05 or P<0.01), being 8.21, 12.51 and 10.98 mmol/100 ml. The variation between the sampling times in the proportions of the different fatty acids was similar in the reindeer and the sheep (Fig. 1). The proportion of acetic acid in the total VFA of the reindeer was 73-78 mol % and the values for the sheep were 61-70 mol %; the proportions of propionic acid were 18-19 and 20-25 mol % and those of butyric acid 3-5 and 8-9 mol %, respectively. In an earlier experiment with reindeer on a silage diet (SYRJÄLÄ 1978), the total VFA of the rumen fluid was higher than in this experiment, averaging 12.3 mmol/100 ml. On a lichen diet it averaged 9.8 mmol/100 ml. The proportion of acetic acid in the total VFA was about 79 mol % on the silage diet and 68 mol % on the lichen diet. The total VFA in the sheep were a little higher than in another study with sheep on silage feeding (SYRJÄLÄ 1972). There were also some differences in the proportions of the individual fatty acids, that of acetic acid being lower and those of the other fatty acids being higher than in the earlier study. Rumen microbiota Number and kinds of ciliate and bacteria cells In both the reindeer and sheep the numbers of ciliate and bacteria cells depended on the sampling being highest before feeding (Fig. 2-3). In this study, however, attention will mainly be directed to the average values of the different sampling times, so that the difference in the eating habits of the reindeer and sheep will not interfere so much with the comparison between the two animals. When the results of this experiment are compared with those in the literature, the values of the samples taken before feeding will be used, because in most of the earlier studies the samples were taken before feeding or as long as some days after feeding. Ciliates. The total number of ciliate cells in the reindeer was less than one third of that in the sheep (P