Utilization of N15-labelled urea in the laying hen. 5. N15-labelling of the content and tissue of separate parts of the gastrointestinal tract

In the series of experiments with labelled urea three colostomized laying hybrids were butchered after a six-day application of 1% urea with 96.06 atom-% 15N excess (15N') in the ration and another 2 days with a supplement of 1% unlabelled urea. Out of the individual samples from crop, gizzard, small intestine, caecum and rectum, the content of the small intestine and the caecum showed the highest labelling with greater than 1 atom-% 15N'. The TCA soluble fraction of the content of the gizzard was more highly and that of the intestines less labelled than the total nitrogen. The tissue of the gizzard is distinctly less labelled than the "omasum system" and the small intestine. The atom-% 15N' of the oesophagus with crop and glandular stomach largely showed agreement in the individual hens with that of intestinal tissue and ranged between 0.71 and 0.89 atom-%. 2% of the 15N' supplemented with the urea could be recovered in the content and the tissue of the gastro-intestinal tract.     

Effect of dietary conjugated linoleic acids on the distribution of fatty acids in serum lipoprotein fractions and different tissues of growing pigs

The effect of conjugated linoleic acid (CLA) on blood lipids [total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triacylglycerols (TAG)] and the fatty acid distribution of the lipoprotein fractions, backfat, muscle fat, and liver lipids were examined in an experiment with two groups of 40 pigs [Pietrain x (Landrace x Large White)] each. The 20 female and 20 male castrated pigs of each group were fed with isoenergetic and isonitrogenous diets supplemented with either 20 g/kg rapeseed oil (control) or 20 g/kg CLA-TAG. The CLA preparation contained 54.2% pure CLA consisting of approximately two-thirds cis,trans/trans,cis-isomers and one-third trans,trans-isomers. The fatty acids of lipoproteins, backfat, muscle lipids and liver lipids were analysed by gas chromatograph (GC). CLA supplementation did not significantly influence blood lipids and the LDL to HDL ratio. In the CLA-fed pigs the very low-density lipoprotein (VLDL) contained higher saturated fatty acid (SFA) concentrations at the cost of the monounsaturated fatty acids (MUFA). The percentage of polyunsaturated fatty acids (PUFA) remained unchanged. The highest CLA content was analysed in VLDL (4.00%) followed by LDL (2.78%) and HDL (1.45%). The ratio of cis,cis to trans,trans isomers increased from VLDL over LDL to HDL. The content of SFA, probably in backfat and muscle lipids, increased whereas the part of MUFA decreased as a result of reduced Delta9-desaturase activity. The percentage of PUFA (without CLA) was higher in backfat of the control group in accordance with the dietary PUFA supply. This shift in the fatty acid distribution was not observed in the liver lipids. In all the three tissues analysed, the CLA-fed pigs had a significantly increased CLA content: the highest increase was in the backfat (5.65%), followed by liver lipids (2.41%), and muscle lipids (1.47%). An isomer-specific accumulation was observed for cis,cis-CLA isomers in muscle, and for trans,trans-CLA isomers in backfat. We conclude that CLA supplementation results in a higher SFA content in backfat and muscle lipids but not in liver lipids. There is a discrimination of the trans-10, cis-12 isomer and the trans,trans isomers in the formation of the cell membranes.     

Effect of iodine, copper and zinc supplements to rations with a high quota of rapeseed extract meal on the growth and thyroid function of fattening swine. 3. The effect on weight and the histomorphometric findings in the thyroid and on the serum T3 and T4 concentrations

Studies were made with a total of 272 fattening pigs. Iodine deficiency both in rations of soya bean meal and rape seed meal increased the weight of the thyroid gland and the height of the epithelium cells and significantly reduced the T4 and T3 level in the serum. Iodine supplements to the rape seed meal rations distinctly diminished the goitrogenic effect, did not, however, cancel it out. Stage of goiter and depression of consumption were--different shown by the T3 and T4 level in the serum. Highly significant relations were calculated between live weight gain, weight and the height of the epithelium cells on the one hand and the T4 level in the serum on the other. Iodine supplementations of rations without thyrostatic components should amount to greater than or equal to 0.1 mg/kg. Iodine supplementations of 0.5 mg/kg feed are at present recommended to rations with rape seed meal quotas of less than 8%.     

Studies on the use of wheat rich in crude protein in the feeding of broilers. 1. Experimental procedure, weight gains, food consumption and food efficiency]

A fattening trial was carried out with 8 groups of broilers each comprising 1225 birds. Within this trial tests were made to replace the protein feeds of newly hatched chicks over a period of up to 56 days of age, by wheat rich in crude protein. If wheat with a high crude protein content is fed supplementation with lysine and methionine will be necessary depending on the kind of protein feed used. No supplementation with amino acids is required if rations of fish meal + extracted soya bean meal are used despite their reduced content of these amino acids. The broilers consumed larger quantities of the wheat + extracted soya bean meal+fish meal ration than of the mixtures containing no fish meal. Food requirements per unit of weight gain were the same for the mixtures containing high-protein wheat and for the standard maize ration. The lowest food consumption per unit of weight gain was computed for the wheat + extracted soya bean meal diet supplemented with amino acids. The same quantities of lysine, thioamino acids and threonine were necessary for broilers receiving the wheat rations as for birds of the standard group. Protein feed may be saved by using high-protein wheat in the fattening of broilers. The rates of weight gain obtained with these rations are the same or even better than those achieved with rations of maize + fish meal+soya bean meal.     

Metabolism of colostomized laying hens with 15N-labeled wheat. 2. Incorporation of the labeled nitrogen into fractions of the egg]

The colostomised hens received 15N-labelled wheat. For a period of 8 days the incorporation of the 15N excess (15N') into the albumen, the yolk and the egg-shell was measured. In addition to that, the values for atom-percent of 15N' in the amino acids lysine, histidien and arginine of the albumen and the yolk were ascertained. The egg-shell and the albumen were labelled shortly after the beginning of the experiment. In both fractions the atom-per cent of 15N' rises more quickly than in the yolk. After the withdrawal of the labelled feed the decrease in the yolk was slower than in the egg-shell and the albumen. Concerning the atom-per cent of 15N' there is hardly a difference between the total N and the amino acids. Despite the different supply with amino acids, the relation of histidine 15N' : lysine 15N' : arginine-15N' in the yolk and the albumen remains largely constant. It is 1 : 2 : 3 and corresponds to the quantitative relation of the N content of the three amino acids in the egg protein. The utilisation of 14N and 15N' of the wheat lysin for the egg synthesis amounts to approximately 50%. There are considerable differences between the utilisation of 15N' of the histidine and 15N' of the arginine and the 14N of the two dietary amino acids.     

Time trends and seasonal variation of iodine content in German cow's milk--investigations from Northrhine-Westfalia

Cow's milk is one of the most important iodine providers in the human diet. The milk iodine content (MIC) is significantly determined by cattle feeding. The aim of the study was to investigate the longitudinal development of the MIC of German cow's milk during the last years and to assess the current contribution of milk consumption to the population's iodine supply. MIC was analysed by a Cer-Arsenit method after alkaline wet washing in 112 milk samples from nationwide available trademarks (eight samples each were purchased in June and December from 2004 onward to 2010 in the same food markets in the greater Dortmund area). We found an increasing trend of MIC until 2010 (p < 0.005).The mean MIC in 2004/05 was 97 +/- 32 microg/I, in 2009/10 it was 110 +/- 36 microg/l. This increase was only observable for conventionally (p = 0.0003), and not for organically produced milk (p = 0.6). The MIC of summer milk was about 22 microg/l lower than that of winter milk (p < 0.0001), however, seasonal variation was especially pronounced in organically produced milk. MIC of organically produced milk was in average about 54 microg/l lower than that of conventionally produced milk (p < 0.0001). Thus, the moderate increase of MIC to 110 microg/l on average contributes to the maintainence of the population's iodine supply, whereas the analysed maximum iodine contents of around 160 microg/l do not give reason to expect an excessive iodine intake, even in case of a high milk consumption. An appropriate iodine supplementation in foodstuff can be assumed.     

Utilization of 15N-labelled urea by laying hens. 1. Survey of the literature, 15N-excretion in feces and urine

Three colostomated leghorn hybrids with an average laying performance of 75% received a ration with 17.7% crude protein and an energy content of 519 energetic feed units for hens per kg mixed feed over a period of 8 days. In the first six days of the experiment the 1%-supplement of urea to the ration was labelled. Its atom-% 15N excess (15N') amounted to 96.06%. During the last two days the urea supplement was not labelled. The total N, trichloracetic acid (TCA)-soluble N and the ammonia N were determined in the feces samples collected daily. In the urine samples collected daily the total N, urea N and ammonia N per hen were determined as well. In all samples the atom-% 15N excess (15N') was measured. The percentage of 14N in feces of the 14N dose was, on an average of the three hens, 21.3% and the analogous quota of 15N' 4.6%. The quota of ammonia 14N of the total 14N in feces had an average of 2.5%, the corresponding 15N' quota was 10.1%. The atom-% 15N' of the urea N in urine was considerably above that of the total urine N and had a maximum of more than 50%. The quota of urine 14N of the 14N taken in had an average of 44.4%, and the corresponding 15N' quota was 56.9%. On an average of the three hens, 61.6% of the 15N' were excreted in feces and urine during the 8-day test period.     

Testing of extracted particles from winter rapeseed with different glucosinolate levels in swine with special reference to the iodine supply. 2. Thyroid hormone status, histomorphometric findings and iodine content of the thyroid gland

In the experiment, 2 x 12 growing pigs received 19 or 6.7 mmol glucosinolates + aglucones/kg feed via conventional rapeseed meal (RSM) or RSM of a newly bred variety. These pigs and 24 littermates pair fed with a soya bean meal (SBM) diet were subdivided in groups of 4 animals each. Their diet contained either no supplementary iodine or an iodine supplementation of up to 1 mg/kg feed. In the RSM and SBM groups the lack of additional iodine lowered the serum T4 and T3 content below the detection limit and caused goitre with about 1 mg iodine in the total thyroid. The SBM diet with 0.0625 mg supplementary iodine/kg increased the serum T4 level and reversed the thyroid enlargement but not that of epithelial cells. The hypothyroidism (goitre and serum T4 level approximately 10 nmol/l) still existed in the case of this iodine dosage together with the RSM of the newly bred variety. A serum T4 level comparable to that of the animals fed SBM was only reached by supplementing the low glucosinolate diet with 0.25 mg iodine/kg feed. The iodine content of the thyroid, however, was reduced by 50 per cent. Though thyroid and epithelial cells were enlarged, this enlargement was not so obvious as in animals exposed to higher glucosinolate level. In spite of 1 mg supplementary iodine/kg feed, the feeding of the conventional RSM resulted in a lower serum T4 level a reduced thyroid iodine content and the enlargement of thyroid and that of epithelial cells. Compared to the high glucosinolate RSM, a significantly lower antithyroid effect of the low glucosinolate RSM was found in pigs with iodine supply. The degree of thyroid enlargement and the serum T4 level were the criteria.     

Studies on the use of wheat rich in crude proteins in the feeding of broilers. 2. Carcass yields and carcass composition]

Studies were made to investigate whether the the substitution of maize for high-protein wheat fed in combination with different protein in fattening rations to broilers would influence the carcass yields and chemical carcass composition of broilers. The described dietary regime was not found to have a significant influence on the different criteria of carcass composition (roaster carcass, flesh, abdominal fat, total proportion of utilizable parts) with the exception of the relative proportion of utilizable offals. The chemical composition of the total body and of all the utilizable parts showed little variation with the different types of feeding. The fat content of all the utilizable parts was much more dependent on the carcass weight of the birds at the end of the fattening period than on the composition of the rations (type of cereals used; supplementation of amino acids).