Hj. Abel

Nutrient contents, rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267 ± 13.6 and 283 ± 18.8 g kg -1 , respectively, which did not differ significantly at P Herz Freya > Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (40-49gkg -1 ). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3.05 ± 0.34 and 1.85 ± 0.09 mg trypsin inhibited g -1 ; lectin 27.2 ± 9.4 and 27.1 ± 5.I mg ml -1 assay medium producing haemagglutination; phytate 15.0+27 and 16.6 ± 2.3 g kg -1 ) were very low. A strong negative correlation (r = -0.92, P<0.001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r = -0.89; P<0001) and organic matter digestibility (r = -089; P < 0.001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r = -0.88, P < 0.001), whereas between tannins and saponins it was significantly positive (r = 096, P < 0001).

Feeding level and diet quality influence trophic shift of C and N isotopes in Nile tilapia (Oreochromis niloticus (L.)).

Many scientists use naturally occurring stable isotopes to reconstruct the diets of animals. However, isotopic ratios may be affected not only by the composition of the diet but also by the amount of food consumed. Thus, an experiment using tilapia (Oreochromis niloticus) was carried out to test the influence of feeding level on δ 13C and δ 15N of fish given a semi-synthetic wheat gluten/wheat starch based diet. In addition, the effect of diet quality was tested by comparing tilapia given this feed with tilapia fed a fish meal/wheat meal based diet. Forty-four tilapia were reared individually. After a prefeeding phase, fish were randomly assigned to five groups, four on the semi-synthetic diet at different feeding levels and one group on the fish meal/wheat meal based diet fed at the equivalent of the highest level of the semi-synthetic diet. The experiment lasted eight weeks. Proximate composition, gross energy content and δ 13C and δ 15N values were determined in feed and fish, for δ 13C separately in the lipids and the lipid-free matter. δ 13C in the lipids and the lipid-free matter and δ 15N of tilapia fed the semi-synthetic diet decreased significantly with increasing feeding rate. The absolute values of the trophic shift in fish fed the semi-synthetic wheat based diet were significantly higher than in fish fed the fish meal/wheat meal based diet. The different δ 13C and δ 15N values in tilapia fed the same diet at different feeding levels and the influence of feed quality on the trophic shift add to the uncertainty involved in the use of stable isotopes in ecological research.

Effects of dl-methionine hydroxyanalogue (MHA) or dl-methionine (dl-Met) on N-retention in broiler chickens and pigs

Abstract Methionine hydroxyanalogue (MHA) was evaluated for metabolic equivalence compared to dl-methionine in practical diets for broiler chickens and pigs. Diets calculated to be deficient in methionine, 2.1 and 1.9gkg −1 in diets for chicks and pigs, respectively, were supplemented with MHA1Alimet ® a registered trademark of Monsanto Inc. 1 or with molar equivalents of dl-methionine from suboptimal to optimal methionine feeding level. A polynomial regression model was used to describe N-retention in response to the dl-methionine or dl-MHA supplemented diets. Both supplements showed equal effects on N-balances of chickens and pigs. N-retention (as proportion of N-intake) was 0.56 and 0.54 in chickens and 0.51 and 0.54 in pigs for dl-Met and dl-MHA, respectively.

Effect of increasing dietary concentrate levels on microbial biotin metabolism in the artificial rumen simulation system (RUSITEC)

The effect of varying hay/barley‐proportions in the feed ration on biotin metabolism of rumen microbes was studied by means of the rumen simulation technique RUSITEC. The stepwise replacement of hay by barley decreased dietary biotin and the net output of biotin by the microbial metabolism. It is concluded that rumen microbes utilise more and/or synthesize less biotin with increasing proportions of dietary barley. These results indicate that a critical reconsideration of current views with regard to the supply and requirement of the high yielding dairy cow for biotin is necessary.

Fiber-related digestive processes in three different breeds of pigs.

The hypothesis examined in this experiment was that, because of intensive selection for greater daily BW gains and efficient utilization of concentrated low-fiber diets, modern pig breeds differ from old local breeds in their physiological ability to respond to soluble dietary fiber. Thus, the old local breeds, Schwaebisch Haellisches Schwein (SH) and Bunte Bentheimer (BB), and a modern crossbred pig (CB) were used in metabolism trials to study fiber-related digestion, including microbial hindgut fermentation, by applying a colon simulation technique (Cositec) and measuring intestinal glucose transport in Ussing chambers. A basal diet or basal plus 20% dried sugar beet pulp (SBP) as a soluble fiber source was fed to 6 pigs/breed in a 2 x 3 factorial arrangement of treatments. Four pigs of each breed per treatment were used for intestinal anatomical measurements at the end of the metabolism trials. The pigs had an initial average BW of 33.9 +/- 3.7 kg. The basal diet was formulated to meet 80% of energy and 100% of nutrient requirements for pigs with 700 g of ADG. Feeding the SBP diet reduced total intestinal tract, but it increased colon length, water-holding capacity of the digesta, and fecal bulk (P < 0.01). The digestibility of OM, CP, and ether extract decreased, whereas that of NDF and ADF increased, by SBP (P = 0.001). Pigs receiving SBP excreted less urinary N and retained more N (P = 0.001). The fecal proportions of undigested dietary and water soluble N increased and those of bacterial and endogenous debris N decreased (P < 0.05) in SBP-fed pigs. The SH pigs had lighter empty cecum weight, shorter colons, and less NDF digestibility than BB and CB pigs (P < 0.05). Fecal N excretion did not differ (P = 0.659) among breeds, but SH pigs excreted more urinary N (P = 0.001) than the other breeds. In Cositec, OM, NDF, and ADF disappearance rates from cecal chyme of SBP-fed pigs increased (P < 0.05) irrespective of pig breed. Cecal chyme of SBP-fed BB pigs produced more VFA with a smaller proportion of propionate and a larger acetate to propionate ratio than chyme of SBP-fed SH and CB pigs. The intestinal epithelial glucose transport was greater for ileal than for jejunal tissues (P < 0.001) but was not influenced by diet and pig breed. In conclusion, the modern and intensely selected pig breed can utilize SBP fiber as efficiently as the old pig breeds under the present experimental conditions.

Investigations on the nutritional value for ruminants of various fats

Abstract Adult wethers were fed at a maintenance level on hay and concentrate in a dry mass ratio of 0.8:1. The concentrate contained 12% barley, which was gradually replaced by the following fats: (I) thermo-refined; (II) hydrogenated; (III) spray fat, starch-coated; (IV) Ca-saponified; (V) Ca-saponified and extremely rich in oleic acid. The fat contents of total rations varied between 3 and nearly 10% in dry matter. The feeding period was 3 weeks, nutrient digestibility being estimated in the third week. Hay and hay plus barley were given in additional digestibility trials. The crude fat digestibility rose in the rations containing Fats I, III, IV and V, but not with Fat II. The highest crude fat digestibility occurred with the saponified fats, in particular Fat V. When barley was replaced by fat, the energy content of the feed concentrates rose by an average of 0.08 (I), 0.05 (II), 0.09 (III), 0.06 (IV) and 0.13 (V) MJ NEL kg −1 for every 1% substitution. Making allowance for the energy value of the substituted barley, the different fats varied between 13.2 and 21.5 MJ NEL kg −1 .

Effect of adding caprylic and capric acid to grass on fermentation characteristics during ensiling and in the artificial rumen system RUSITEC

Silage was prepared from grass that was treated either with caprylic or capric acid, prior to ensiling, to increase aerobic stability. The silage was introduced to the RUSITEC in order to measure the effect of treatment on in vitro microbial metabolism. Although, caprylic acid inhibited lactic acid formation during the ensiling process, aerobic stability was high. Capric acid did not interfere with lactic acid production yielding silage with moderate stability. In RUSITEC neither caprylic nor capric acid had an effect on protozoa counts, but both lowered apparently degraded organic matter (OMAD). Caprylic acid promoted methane and acetate production while propionate production and microbial yield were lower. Capric acid had no effect on the production of methane, acetate and propionate; butyrate production increased and microbial yield remained unaffected. Caprylic and capric acid are highly preservative, yielding silage of good quality and high aerobic stability indicating their efficiency against spoilage micro-organisms. The bactericidal effect however, was modified during the ensiling process since both lost some toxicity against rumen protozoa and methanogenic bacteria. Net production of rumen microbial cell mass per unit OMAD was not impaired.