The effect of monensin Na on the protein content of cow's milk and further performance criteria

In two feeding experiments with 10 dairy cows each the effect of 200 mg monensin Na per animal and day in rations either rich in roughage or in concentrate was studied. In principle, the reactions caused by monensin supplement did not differ between the two types of rations. Monensin supplements resulted in a slight reduction of feed intake, a significantly lower milk fat content and, as a tendency, also a lower milk protein, particularly casein, content and a diminished amount of fat corrected milk (FCM). The pattern of fatty acids in the rumen was shifted in favour of propionic acid and the live weight gain of the cows was higher in the monensin group. There were no improvements with regard to the expenditure of feed and energy per kg FCM.     

Vitamin E requirement of chicks and young hens

In 4 experiments young chickens of the species White Leghorn received semisynthetic rations with a vitamin E content less than 1 mg/kg basal ration. Sunflower oil heated with FeCl3 supplement was used as a factor increasing requirement. Feed intake, live weight gain and feed expenditure with semisynthetic rations without oil supplements did not depend on vitamin E supplements. After the feeding of rations without vitamin E animal losses were higher. The losses were normalized by 1 mg vitamin E supplement per kg feed. Rations containing sunflower oil without vitamin E supplementation resulted in encephalomalacia of the young chickens. Vitamin deficiency increased triiodine thyronine content in the blood plasma. Antibody formation after the application of human gamma globulin did not depend on the vitamin E supply studied. A vitamin E requirement of young chickens and young hens of the laying species of less than 1 mg/kg mixed feed is derived from the results.     

The effect of straw meal on the crude protein and amino acid metabolism and digestibility of crude nutrients in broiler hen breeds. 1. Problems, experimental review and N-excretion in the urine

The metabolization of the straw N and the influence of the straw on N excretion in urine were studied in 2 experiments with colostomized broiler hens and with 15N labelled wheat straw as well as 15N labelled wheat. In experiment 1 the test animals divided up into 4 groups received 0 g, 20 g, 30 g and 40 g straw meal per animal and day in addition to 120 g mixed feed. The daily 15N-excess (15N') intake from the straw was 18.4 mg, 27.5 mg and 36.7 mg. The amount of 15N' daily consumed with the labelled wheat in experiment 2 was 119.7 mg. 40 g straw meal resulted in a significantly increased amount of urine (p less than 0.05). The amounts of urine N and uric acid N were only increased as a tendency. On average the productive N decreased as a consequence of the straw meal supplement from 1070 mg/animal and day (control) to 764 mg/animal and day after 40 g straw meal supplement. The productive 15N' of the labelled wheat was not influenced by the straw meal supplement. The productive 15N' of the straw increased from 3.8 mg/animal and day (20 g straw) to 13.4 mg/animal and day (40 g straw). In contrast to 15N wheat, straw as a 15N source resulted in a lower labelling of uric acid N in comparison with urine N. It can be assumed that the changed metabolization of the straw N is influenced by microbial processes in the intestines.     

Effects of dietary potassium and sodium on magnesium utilization in sheep

Two metabolism trials were conducted to determine the effect of altering dietary Na and K on Mg availability. Three dietary treatments (normal K-normal Na, high K-normal Na and high K-high Na) were imposed upon nine crossbred wether lambs in a randomized block design. Each trial consisted of a 5-d diet adjustment, a 10-d preliminary period and a 5-d collection of feed, feces and urine. Increasing K and Na intake increased the percentage of Mg excreted in feces. Both elevated K and K-Na depressed (P less than .10) urinary Mg excretion, primarily a reflection of depressed Mg absorption in animals fed these diets. Apparent K absorption and retention increased when animals were supplemented with K. Addition of Na to the diet did not alter absorption or retention of K. Apparent K and Na availability increased when K and Na supplements were included in the diet. This increased availability resulted from increased total absorbed K and Na compared with a fixed endogenous excretion. Calcium balance in lambs was not affected by addition of K or Na. Lambs were able to absorb enough Mg from their respective diet to maintain normal serum Mg levels. Addition of Na to a diet high in K did not enhance Mg absorption in lambs.     

The influence of different fiber types on the fecal nitrogen excretion and the content of volatile fatty acids in the feces of broiler hen breeds

4 colostomized adult broiler breeding hens each received 120 g mixed feed per day. In addition, the animals were given 10, 20, 30 and 40 g/day cellulose powder or apple pectin resp. and 10, 20, 30 g/day straw cellulose. The DM content of the faeces was increased by cellulose powder and decreased by pectin (P less than 0.01) in comparison to the control group. DM excretion in g/animal and day increased more quickly after supplementing cellulose powder than after supplementing pectin. Straw cellulose produced results in between. The fibre supplements increased N excretion in faeces. It was, however, only significantly increased per 100 g DM intake by large pectin supplements (greater than 20 g). The TCA soluble N quota in the total N of the faeces remained largely unchanged after pectin supplements and increased after cellulose and straw cellulose supplements. Pectin supplements significantly increased the formation of acetate, propionate and butyrate in comparison to the other groups. Propionate could sporadically be detected in the faeces of the other test animals, butyrate not at all. In combination with 40 g apple pectin/animal and day, Bisergon (chinoxalin derivative) increased the formation of the 3 volatile fatty acids significantly.     

Vitamin E requirements of laying hens

In 5 experiments with 1,296 laying hybrids at the age of 22-73 weeks producing eggs for consumption a varied supplementation of between 0 and 20 mg vitamin E per kg of a semisynthetic ration was tested. The vitamin E content of the basal ration was less than 1 mg per kg feed. The quotas of selenium and unsaturated fatty acids in the feed were taken into consideration. Vitamin E and Se supplements did not influence, feed intake, laying, performance, feed efficiency/100 g egg development of body weight and mortality. The supplementation of 14% vitamin-E-free sunflower oil caused a significant decrease of the laying performance by 15%. There was no relation between the humoral immune reaction and vitamin E supply. The peroxide value of the abdominal fat and the activities of the creatine phosphokinase, the aspartate and alanine amino transferase in the blood serum were not directionally changed by the vitamin E, Se and oil supplements. There were no significant relations between the vitamin E content of the feed and that of the yolk and the yolk sac of the chicken. A vitamin E requirement of less than 1 mg and a requirement norm, including a safety margin, of 5 mg per kg feed was derived from the results for laying hens for egg production. A supplement of synthetic vitamin E to laying hen feed is thus not necessary.     

Effect of the polyether antibiotic "monensin" on fattening and slaughtering performance as well as protein and energy retention in bulls

In an individual feeding experiment (150-500 kg live weight) the influence of the polyether antibiotic Monensin on the fattening, slaughtering and retention performances of crossbreeding dairy bulls (genotype 31) and fattening hybrids (genotype 61) was ascertained. The supplementation of the polyether antibiotic on average resulted in a decrease by approximately equal to 11% of the dry matter and energy expenditure per kg weight gain due to a lower feed intake and a higher live weight gain. The slaughtering parameter investigated and the chemical composition of the empty body remained uninfluenced. The daily nutrient retention values were positively influenced by the Monensin supplementation since the fattening bulls of the test group required 30 days less to achieve the attempted fattening weight. The additional retention of protein, fat and energy per animal and day in the dairy bulls approximately equal to 10.9; 13.5 and 16.4% and in the fattening hybrids 1.9; 3.2 and 2.6%. Due to a higher energy retention at a lower level of feed and energy intake after Monensin supplementation an average of approximately equal to 11.3 and 15.4% resp. more of the consumed digestible protein and the digestible energy resp. were retained in the empty bodies. One can conclude that Monensin improved the utilisation of feed energy; obviously the effect of the polyether antibiotic is due to its influence on processes in the rumen or directly or indirectly on metabolism.     

The effect of avoparcin on apparent digestibility, characteristics of rumen fermentation and fattening and slaughter output of growing cattle

Four digestion experiments with 5 wethers each (0, 15, 30 or 60 mg avoparcin per animal and day), three individual feeding experiments (28, 18 or 56 bulls per experiment; 0 and 150/200; 0, 250 and 500 or 0 and 200 mg avoparcin per animal and day in the experiments 1, 2 or 3) and two group feeding experiments (60 bulls and 161 heifers per experiment; salt lick stones without or with 2.5 g avoparcin per kg) were carried out in order to investigate the influence of avoparcin on apparent digestibility, figures of rumen fermentation, fattening and slaughtering results as well as protein, fat and energy retention. Avoparcin supplementation did not significantly influence the apparent digestibility of organic matter and crude nutrients. Concentration of acetate of rumen liquid was decreased (16 or 36) and that of propionate was increased (25 or 50 mmoles per mol) when 200 or 500 mg avoparcin per animal and day were added. Acetate:propionate ratio decreased from 4.2 to 3.5 and 3.1:1. Avoparcin did not influence feed intake, enhanced daily weight gain (37 to 174 g per animal and day) and improved feed efficiency (5 to 26%). Salt lick stones with avoparcin increased weight gain (58 and 96 g per animal and day). Slaughtering results and body composition of bulls were not influenced by avoparcin. Daily retention of protein, fat and energy was significantly increased (16 to 18%; P less than 0.05) when avoparcin was supplemented.     

Administration of monensin in self-fed (salt limiting) dry supplements or on an alternate-day feeding schedule

Two series of trials were conducted to evaluate alternative methods of administering monensin to pasture cattle. In a series of five trials, monensin was incorporated into supplements at 440 mg/kg to provide an average intake of 200 mg X head-1 X d-1 for growing cattle on pasture. Comparisons were made between daily and alternate-day feeding of the supplements. A control treatment consisting of unmedicated supplement fed daily also was included. Monensin at 200 mg/d and 400 mg on alternate days increased gain by .077 (P less than .01) and .082 (P less than .01) kg/d above control-cattle gains (.54 kg daily). Nine pasture trials were conducted to compare the effectiveness of monensin in increasing the daily gain of growing cattle when hand-fed daily in a supplement or self-fed in supplements that contained salt to regulate supplement intake. Desired supplement intakes were approximately .454 kg X head-1 X d-1 in six trials, .68 kg/d in one trial and 1.81 kg/d in two trials. Monensin produced gain increases of .09 kg daily (P less than .01) with both feeding systems. The daily gains of cattle that were hand-fed and self-fed were equal (P greater than .10). Self-fed treatments containing monensin required fewer changes in salt level than self-fed treatments not containing monensin, and the salt levels required to limit intake were generally 25 to 50% lower when monensin was in the supplement.     

Effects of supplements containing different additives on nutritional and productive performance of beef cattle grazing tropical grass

A grazing trial was carried out to evaluate the inclusion of three feed additives in supplements (crude protein, CP 230 g/kg dry matter, DM) on the performance, voluntary intake, and digestibility of beef heifers grazing Brachiaria decumbens (CP 81 and neutral detergent fiber, NDF 615 g/kg DM). Thirty-five Nellore heifers (21 months of age and 383 ± 6.29 kg of body weight, BW) were used in a completely randomized design. The treatments were as follows: no supplement (control); supplement fed at 1 kg/animal/day without additives (S); supplement with monensin (S + M); supplement with yeast culture (S + YC); and supplement with enzyme complex (S + EC). All of the supplemented heifers had greater (P < 0.1) average daily gain (～0.186 kg/day) compared to the control treatment (0.014 kg/day). Average daily gain and final BW were similar (P > 0.1) among supplemented heifers. Monensin inclusion in the supplement decreased (P < 0.1) forage DM (expressed as g/kg BW) and NDF intake (expressed as kg/day and as g/kg BW). All of the feed additive inclusions decreased (P < 0.1) NDF digestibility. In conclusion, the heifers’ performance was improved by concentrate supplementation. However, the inclusion of additives did not enhance this effect.     

Effects of high dietary sodium chloride content on performance and sodium and potassium balance in growing pigs

Thirty castrated male Moo Lath pigs (6–8 weeks of age) were used in a 15-week growth trial to study the effect of high dietary sodium chloride (NaCl) content on feed and water intake, performance, sodium (Na) and potassium (K) balance, and plasma aldosterone concentration. The pigs were randomly allocated (ten per treatment) to diets containing 0.24 % Na (Na0.24), 0.28 % Na (Na0.28), and 0.32 % Na (Na0.32) per kg diet. Feed and water was provided ad libitum, and water consumption, feed offered, and feed residues were recorded daily. Every third week, the pigs were weighed, blood samples were collected, and a 3-day total collection of urine and feces was performed. Water intake was higher (P?=?0.001) in pigs fed with diets Na0.28 (3.7 L/day) and Na0.32 (3.9 L/day) than in pigs fed with diet Na0.24 (3.4 L/day), and dry matter (DM) intake was higher on diet Na0.32 (P?=?0.041) than on the other diets. The average daily body weight (BW) gain was higher on diet Na0.32 than on the other diets (P?=?0.031). The feed conversion ratio (in kilogram feed DM to kilogram BW gain) was 4.6, 4.6, and 4.1 on treatments Na0.24, Na0.28, and Na0.32, respectively (P?=?0.14). The highest Na balance was observed on diet Na0.32 followed by diets Na0.28 and Na0.24 (P?<?0.001), while there was no treatment-related pattern for the K balance. The Na/K ratio in feces and urine increased (P?<?0.001), and the K/Na ratio in feces (P?<?0.001) decreased with increasing Na content in the diet. Plasma aldosterone concentration decreased (P?<?0.001) with increasing dietary content of Na. These results indicate that high NaCl intake and free access to water will increase Na balance but do not negatively influence feed intake and performance of growing local pigs.     

Urinary delta-aminolevulinic acid levels in dairy cows during lead loading from feed rations under normal conditions of rearing in the Western Slovakia Region

The concentration of delta-amino levulinic acid (ALA) was determined in the urine of clinically healthy cows of 14 herds in the West-Slovakian region. The content of lead was determined at the same time in the components of feed rations. The ALA concentration values were converted to values per uniform specific weight of urine and per gram of secreted creatinine to match literary sources where the ALA concentration is given in these two quantities. The approximate intake of lead by the animal bodies in milligrams per head/day and per kg of live weight was calculated from lead content in feed rations. The average ALA concentration in the urine of dairy cows was 42.7 +/- 20.2 mu mol per 1 of urine (36.8 +/- 18.7 mu mol per g of creatinine), the average lead intake from feed being 0.157 mg per kg of live weight. The ALA concentrations in urine refer to animals given normal feeds with no lead contamination and as such can be considered as physiological values. Statistically significant correlations were recorded between ALA concentrations per litre of urine at the uniform specific weight of 1030 g per litre and the values converted per gram of secreted creatinine (r = 0.789). The upper biological tolerance limit of ALA concentration in urine (105.0 mu mol per litre) was determined by mathematico-statistical methods. Values above this limit could be indicative of an increased lead stress of the cows' bodies.     

The course of phosphorus excretion in growing pigs fed continuously increasing phosphorus concentrations after a phosphorus depletion.

A balance study was performed in order to quantify the effect of continuously increased phosphorus (P) intake on faecal and urinary P excretion. The aim was to quantify the level of intake where regulatory P excretion becomes relevant for comparative digestibility measurements on P, and when the pig adapts its urinary P excretion to increased P intake. Phosphorus intake of growing pigs was continuously increased on a daily basis starting at a marginal level and P excretion via faeces and urine was continuously followed for 92 days. Two semi-synthetic diets were prepared with different proportions of Na2HPO4 resulting in 2.4 (diet 1) and 6.3 (diet 2) g P/kg DM. Concentration of Ca was adapted to achieve a Ca supply approximately 3.1 fold the digestible P supply. Six castrated male crossbred pigs (31 kg BW) were kept individually in metabolism crates after they had undergone a 14 d P depletion period during which they were fed diet 1 solely. Pigs received 1.04kg of diet 1 per day throughout the experiment, and each day the amount of feed and P supplied to pigs from diet 2 was increased by 12 g and 69 mg, respectively. ME supply was approximately 2.4 fold maintenance and average daily BW gain of pigs during the entire experiment was 690 +/- 30 g. While intake increased linearly, faecal excretion of P and Ca increased non-linearly and could be best described by third order polynomial functions. The proportion of ingested P not excreted via faeces followed a quadratic type of curve with a maximum of 81% at 25 days on experiment and P intake of 4.0 g/d. Thereafter, the proportion decreased continuously. The digestibility of P from diet 2, determined by the slope ratio technique, was constant and not affected by P intake up to a P intake of 5 g/d. Renal P excretion did not exceed inevitable losses until day 60 and increased exponentially thereafter when body P reserves were restored. It is concluded, that an adaptation to surplus P supply occurred earlier on the intestinal than on the renal level. While faecal P excretion appeared regulated depending on the actual requirement for P retention, the regulation via urine depended on the P status of the pig. Once the renal P excretion of growing pigs exceeds a level of 25 mg/d, intake of digestible P cannot be regarded sufficiently low to measure P digestibility as a capacity of the feedstuff.     

Effect of flavomycin on the apparent digestibility of crude nutrients in wethers, parameters of rumen fermentation in cattle and feed intake and weight gain of heifers

Three experiments with five wether each were carried out in order to investigate the influence of various levels of flavomycin (0, 5 and 10 mg per animal and day) on apparent digestibility of artificially dried grass. A short time individual feeding experiment (42 days) with 9 bulls and a long term individual feeding experiment (225 days) with 52 heifers were conducted. Animals consumed 0 or 30 mg flavomycin per day. Parameters of rumen fermentation were investigated. Feed intake and weight gain were measured in the experiment with heifers. Flavomycin did not significantly influence the apparent digestibility of organic matter and crude nutrients as well as parameters of rumen fermentation. Flavomycin did not influence dry matter intake, but increased significantly weight gain (49 g per animal and day, 10.5%) and reduced feed and energy required per kg weight gain (10.6%) in heifers. The reasons of ergotropic effects of flavomycin are mostly unknown at present.     

Use of sodium acetate in feed rations in ketotic cows

On a farm where the ration of cows contained 88.0 g of butyric acid, an experimental group of cows (n = 8), producing milk containing 7.9 mg or more acetone per litre, was studied for 14 days for the effect of a 250 g supplement of sodium acetate to the ration (combined with single i.m. administration of vitamins A, D2 and E) on selected metabolism parameters and on milk production. As distinct from the control group of cows (n = 8) from the same farm which produced milk containing 3.9 mg or less acetone per litre and which were fed without sodium acetone supplements, a tendency of increased alkaemia of the organism was suggested in the experimental cows. This tendency manifested itself during the trial in increased pH values, increased base excess (BE) and standard bicarbonate (SB) in the blood, and in an increase in the pH value and net acido basic secretion in urine. A decrease was recorded in the concentration of the acetone + acetacetic acid sum, the same as beta-hydroxybutyric acid in blood and the sum of acetone and acetacetic acid in milk (P less than 0.01). An insignificant increase of the activity of gammaglutamyl transpeptidase (GMT) was recorded in the blood serum of the experimental cows and a significant increase occurred in the content of potassium (up to P less than 0.01) and urea (up to P less than 0.01) in urine. The supplement of sodium acetate to the feed ration did not influence the degree of ketonuria and the finding of urobilinogen in urine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of different non-chloride sodium sources on the performance of heat-stressed broiler chickens

1. One hundred and eighty 1-d-old broiler chicks were used to evaluate the effect upon broiler performance during severely hot summer months of three different sodium salts: sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3) and sodium sulphate (Na2SO4), in starter and finisher diets having an identical electrolyte balance (DEB) of 250 mEq/kg. 2. The non-chloride sodium salts were added to contribute the same amount of sodium and were substituted at the expense of builder's sand in the basal diets containing common salt (NaCl) as Na and Cl source. 3. Each diet was fed to three experimental units having 15 chicks each until 42 d of age. Severe heat-stress conditions, maintained in the rearing room, were indicated by high average weekly room temperature (minimum 29.3 degrees C; maximum 38.0 degrees C). 4. Diets containing sodium salts gave better body weight gain, feed intake and feed to gain ratio than the control diet. Sodium salts also enhanced water intake as well as water to feed intake ratio. This effect was more pronounced in broilers fed NaHCO3 supplement (with NaCl in the basal diets). 5. The increased water intake resulted in lower body temperature in heat-stressed birds fed NaHCO3 supplemented diet than in birds fed other sodium salts. A lower mortality rate was noted with NaHCO3 (15.15%), Na2CO3 (13.64%) and Na2SO4 (15.15%) supplements than with the control (33.33%) treatment. 6. Better carcase and parts yield were observed in sodium supplemented broilers. Sodium salts reduced the alkalotic pH and enhanced the blood sodium content, which ultimately improved the blood electrolyte balance and overall performance of heat-stressed broilers. 7. Supplementing broiler diets with sodium salts improved the live performance of heat-stressed broilers and better productive performance was noted with NaHCO3 than other sodium supplements.     

The use of mixed feed with reduced content of vitamin A, E and nicotinic acid in the fattening of cairinas

In three fattening experiments with 1344 male cairinas (Cairina moschata domestica L.) from hatching to the 77th day vitamin A supplement was reduced to 2500 IU/kg feed from hatching to the 21st day and to 1250 IU/kg feed from the 22nd to the 77th day. There was no supplementation of the feed with vitamin E or nicotinic acid. The reduction and elimination of the vitamin supplements on average did not have significant effects on fattening performance, feed intake, body weight, feed conversion and losses of animals in the starter and fattening periods. In the fattening period there was a tendency towards a higher intake and expenditure of feed in two experiments. Presumably the supplementation of 1250 IU/kg mixed feed is not always sufficient for an optimal fattening performance. In three production experiments with 33,850 cairinas no disadvantageous influence on fattening performance could be ascertained after a supplementation of 4,000 IU in the starter feed and 2,000 IU vitamin A in the fattening feed.     

Effects of supplemental feed with or without ionophores on lambs and Angora kid goats on rangeland

Effects of supplemental feed and of ionophore concentration in supplemental feed on gastrointestinal rate parameters, forage intake and weight gain were measured in individually supplemented grazing lambs and Angora kid goats. The 12 dietary treatments included negative control (NC; grazed forage only), positive control (PC; grazing plus 13.6 g supplement DM/kg.75), and PC plus monensin or lasalocid, each at 33, 66, 99, 132 or 165 mg/kg in the supplement. Gastrointestinal fill, retention time, turnover rate and fecal output were estimated by applying a single-compartment model to the fecal excretion of a single dose of ytterbium. Forage digestibility was estimated from forage and fecal concentrations of indigestible fiber. Supplemental feed increased digestibility of forage and total intake in sheep but had no effect on forage intake. In goats, supplemental feed did not increase digestibility of forage but decreased forage intake. Supplemental feed increased weight gain in both species. Increasing the monensin concentration in supplemental feed reduced supplement intake greatly in sheep and slightly in goats. Lasalocid did not affect intake of supplement by either sheep or goats. Overall, ionophores had minimal effects on the response criteria. Because feed intake and digestibility were not affected, any increase in gain or efficiency in lambs or kid goats on rangeland from consumption of ionophores must be a result of their therapeutic value or of improved physiological efficiency.     

Partitioning of nutrient and trace elements in feed between body retention,faeces and urine by growing dairy-breed steers

The partitioning of nutrients and trace elements from feeds, drinking water and mineral supplements on growth, faeces and urine of growing cattle was studied with eight steers in a balanced Latin square design with two replicates, each comprising four treatments (diet compositions), four periods and four animals. The treatments were four rations with a silage proportion of 15, 30, 60 and 100% of the dry matter. Records were taken of the individual intake of silage, concentrates, mineral supplements and water, and excretions by collecting all urine and faeces. All feeds, urine, faeces and water were analysed for their content of Al, Ca, Cd, Cl, Co, Cu, Fe, K, Mg, Mn, Mo, N, Na, Ni, P, S, Se, and Zn. Elements that were mainly excreted in faeces (Ca, Cd, Cu, Fe, P, and Zn) tended to have a constant uptake in amount. As there is a fairly good correlation between DM consumption and faeces production, it is possible to estimate the amount of these elements excreted at farm level by analysing a faeces sample. Elements that are excreted in significant amounts in both faeces and urine (Cl, K, Mg, Mo, N, Na, S, and Se) tended to have a constant uptake over treatments as a fraction of the feed content. It is more difficult to estimate the amounts of these elements at farm level because it is more difficult to predict urine production than faeces production.     

Choline requirement of the laying hen. 2. Effect of methionine and fat content of rations on choline requirement

165 laying hens per group received 3.0, 3.5, or 4.0 g methionine, 29 or 59 g fat and supplements of 0, 108, 217, 434 or 868 mg choline per kg feed resp. (3 X 2 X 5) over a period of 336 days. The average laying performance was 70% and was not influenced values by the content of the feed. The methionine supplements significantly increased the weight of the eggs by 0.6 and 1.1 g resp. The higher fat content increased the weight of the eggs by 0.6 g. Feed expenditure was not influenced by the subject of the experiment. The results of the experiment show that laying hens do not require choline as feed supplement and that therefore no interactions between choline and the fat and methionine content of the ration are to be expected.