To investigate effects of hay intake and feeding sequence on indicators of the microbial activity within the hindgut, six horses were fed 1.00 kg oats plus 0.50, 0.67, 0.83 or 1.00 kg hay/100 kg body weight (BW) · day, each for 14 days. Oats was offered either 30 min prior to hay (OA) or in the reversed sequence (HA) in a 2 · 8-week crossover design. Because typically exercised horses should be subjected to the study, faeces was used as substrate. Faecal dry matter (DM), the faecal watersÕ short-chain fatty acids (SCFA, in mmol/l) and molar percentages (mol%) of propionate and iso-butyrate were highest with OA (p < 0.01). Acetate mol%, acetate-propionate quotient (A/P) and buffering capacities 1 and 2 (BC1: current pH to pH 6; BC2: pH 6 to 5) of the faecal water were highest with HA (p < 0.01). While the hay intake rose, faecal pH, acetate mol%, A/P, BC1 and BC2 (the latter with HA only) increased (p < 0.05), but DM, SCFA and propionate mol% declined (p < 0.05). The hay-induced rise in A/P and BC1 was much higher with HA than with OA. l-Lactate and ammonia were unaffected by the feeding sequence and hay intake. In conclusion, hay intake and feeding sequence influence the microbial activity within the hindgut, although the concentrate level remains consistent. In horse rations with 1.00 kg oats/100 kg BW · day amounts of at least 0.83 kg hay/100 kg BW · day and offering the hay first seem to have the potency to protect the hindgut content from acidification. Behavioural abnormality was not observed any longer first with 1.00 kg hay/100 kg BW · day.

Lambs of an age of 2 or 4 months and of an average live weight of 14.7 and 27.4 kg resp. received rations consisting of 44% cereals, 46% dried sugar beet pulp, 6% wheat starch, 2% urea and 2% mineral-vitamin mixture. The crude protein content was 17.1 and 15.9% resp. in the dry matter, that of native crude protein 10.6 and 9.4% resp. During a 6-day N balance period 8 and 16 g 15N urea resp. with a 15N excess (15N') of 9.26 and 9.40 atom-% were fed orally instead of commercial feeding urea. There were no significant differences between the two age groups with regard to the digestibility of the organic matter and the crude nutrients. The average N balance of 372 +/- 85 mg/kg LW 0.75/day were in the intermediate range of N retention capacity and accounted for 26 +/- 5% of the consumed N. N retention in per cent. was slightly lower in younger lambs. Projections of urea utilization in a quasi stationary state resulted in an efficiency of the utilization of 33 +/- 4%. The dismembering of the lambs at the end of the main period showed between 0.02 and 0.22 atom-% 15N' in the total N, TCA precipitable N and amino acid N of the meat. At between 0.24 and 0.38 atom-% 15N' they were highest in the heart and jaw muscles. The quota of 15N' amounts found in the total N of the meat were 10.6 +/- 3% of the 15N-intake and 20.1 +/- 5.1% of the 15N' amount remaining in the body. The bones contained 7.7 +/- 1.7% and the fleece 7.9 +/- 3.1% of the 15N'-intake. Generally seen, the total N and urea utilization was slightly lower in younger lambs than in older ones.

Stickstoffbestimmung, Methodik 3 verschiedene Stickstoffmengen wurden vergleichsweise an 4 NH,-Destillationsapparaturen, die bei der N-Bestimmung nach KJELDAHL gebrauchlich sind, in jeweils 20 Wiederholungen destilliert. Die im Mittel wiedergefundenen Stickstoffmengen und die Standardabweichungen waren far eine PARNAS-WAGNER-Apparatur herkammlicher Bauart und ftir eine modifizierte P~NAS-WAGNER-ApparUr nach KUNZE u. a. am Onstigsten zu beurteilen. Der Arbeitszeitaufwand wurde ffir die Apparatur nach KUNZE u. a. und ftir die Apparatur nacii DIRKS am niedrig6ten eingeschatzt.

Die vorliegende Untersuchung befaßt sich mit dem Einfluß der Emährung auf das Fettsäurenmuster in der Lipidfraktion von Stutenmilch. Zunächst wurden an 2 x 3 Stuten die Milchlipide bei Weidelütterung mit geringem Konzentratanteil und bei einer haferreichen Stallfutterration untersucht (A). In zwei werteren Versuchen an 2 x 2 und 2 x 3 Stuten wurden die Fettsäuren im Milchfett bei der Gabe eines fettreichen Mischfutters mit einem hohen Gehalt an langkettigen, mehrfach ungesättigten Fettsäuren (B) und von Sojaöl (C)jeweils im Vergleich zu einer Kontrolle geprüft. Bei Weideführung war der Anteil an mittelkettigen Fettsäuren sowie an Palmitoleinund an Linolensäure gegenüber Stallfütterung erhöht, während die Ol-und Linolensäurekonzentrationen in den Milchlipiden bei der Stalltutterration deutlich höher waren. Bei der Gabe von Futterfetten mlt einem hohen Anteil an langkettigen, mehrfach ungesättigten Fettsäuren ist der Anteil an Palmitinund z.T. auch an Pentadecanund Pentadecensäure vermindert, während die Linolsäurekonzentration in den lvlilchlipiden deutlich ansteigt. Die Erhöhung der Linolsäurekonzentration erscheint um so deutlicher, je zeitiger in der Laktation mit der Fettgabe begonnen wird. Schlüsselwörter: Stute, Milch. Fettsäuren Investigations on fatty acid composition in mares milk This investigation deals with the influence of nutrjtion on fatty acid composition in the lipids of mares milk. The first trial (A) with 2 x 2 mares compared a diet for mares on pasture (low proportion of oats) with a typical diet for winter season without any green feed (high proportion ol oats). ln the next two trials 2 x 2 (B) or 2 x 3 (C) mares were fed a diet with a faFinriched mixed feed (high proportion of long-chain polyunsa' turated fatty acids) (B) or with soybean oil (C). Each case was compared with a control. N,4ares on pasture had a higher proportion of medium-chain fatty acids and of palmitolenic and linolenic acids but lower oleic and linoleic acids in the milk lipids then mares fed in the stable. Feeding a diet rich in long-chain unsaturated fatty acids led to a lower proportion of palmitic and partly of pentadecanic and pentadecenic acids in the milk lipids. Simultaneously the proportion of linoleic acid in the milk lipids was much higher when high fat diets were given. This effect of feeding fat on the proportion of linoleic acid seems to be more pronounced when the mare consume the high fat diet in an early state of iactation.

In an experiment 12 lambs of the merino species were divided into 4 groups. The variants HE received 740 or 718 EFU cattle/kg DM and the variants NE 689 or 671 EFU cattle/kg DM. The different energy concentrations resulted from differentiated quotas of dried sugar beet chips and wheat starch supplements. Within the variants, sub-variants with (HESZ, NESZ) or without (HES, NES) sugar supplements were formed. Due to varied DM intake, the average energy intake in all groups was 42 EFU cattle/kg LW0.75. N balance experiments using 15N-labelled urea were carried out, and 15N accumulation of N excretion was projected to a steady state. The partial utilization of pure protein and NPN in the ration was ascertained with the help of a 3-pool compartment model of N utilization in ruminants. In the non-amino acid N pool HE utilized 84% of NPN and NE 77% for the synthesis of amino and nucleic acids. The efficiency of protein synthesis in the amino acid N-pool were in HESZ 64%, HES 70%, NESZ 70% and NES 73%, resp. The total utilization of NPN is the sum of the partial utilization in the two pools, whereas the total utilization of pure protein is calculated from the true digestibility and the efficiency of the utilization in the AA-N pool. The total utilization of NPN for the synthesis of protein for the protein pool amounted to 40/35/41/33% and that of pure protein to 54/51/49/50%. Energy intake being identical, energy concentration did not have an influence on the utilization of pure protein and NPN, whereas NPN utilization was better in rations containing sugar. The pure protein in the ration was by 19 ... 52% better utilized than NPN.