Nutritive physiological effects of dietary fats in rations of growing swine. 6. Effect of soya oil and lard on growth performance and carcass characteristics and various blood parameters in fattening swine

Groups of each 10 boars, weight range 20-60 kg, were fed ad libitum the following 4 rations of similar protein: energy ratio: Ration I (control), Ration II (+ 2% soyaoil ), Ration III (+ 2% soyaoil + 5% lard), Ration IV (+ 7% lard). When the animals reached 60 kg body weight each group was halved. One half had free access to the above rations, while the other half were fed ad libitum on the control ration. At body weights of 50 and 100 kg the concentrations of urea, insulin, glucose and cholesterol were measured, in addition the fatty acid composition of the backfat. At the end of the experiment (100 kg) the content of fat in the carcass was calculated by determining the specific gravidity of the carcass. There was little difference in the intake of metabolizable energy (ME) of the different groups of animals at both body weight ranges as a result of the reduction in feed intake of the fat supplemented diets on account of the higher ME-content. There were little differences in the glucose and urea concentrations in the blood of the animals fed the different rations. The highest cholesterol and the lowest insulin levels were measured in groups III and IV, when 5 and 7% lard was added, respectively. The animals, continuously fed Rations III and IV over the whole period of experiment, had a significantly higher fat content (p less than 0,05) than the control animals. There was a very marked influence of the fatty acid intake on the fatty acid pattern of the backfat. Following the change of feed to the control ration at 60 kg body weight, the linoleic acid content of the animals in Groups III and IV was significantly reduced (p less than 0,001) from 15.7 to 11.2%. However this was higher than the 7.3% linoleic acid measured on the animals continuously fed the control ration.     

Nutritional-physiological effects of dietary fats in rations for growing pigs. 4. Effects of sunflower oil and coconut oil on protein and fat retention, fatty acid pattern of back fat and blood parameters in piglets

Rations containing 12% sunflower oil (Ration II) and 12% coconut fat (Ration III) were compared with a control ration (Ration I) in a 34 day experiment with growing boars of the German Landrace breed (12-30 kg body weight). The relationships between DP and ME were held constant for all 3 rations, and because of the higher ME contents of the two fat rations, this was achieved by reducing the feed intake, relative to that of the control ration. Parameters measured were growth, composition at slaughter, the apparent digestibility of the crude nutrients and energy, the N-balance and the concentrations of urea, insulin, glucose, triglyceride and cholesterol in the blood. In comparison to Ration I, the apparent digestibilities of crude protein in Rations II and III were 5 and 4% (p less than 0,05) higher, respectively. There was little difference in the apparent digestibility of crude fat between the Rations II and III. However, large differences in the values were determined depending upon method of extraction. There were little differences in the productive performance of the animals fed the fat diets. The control animals had, however, a 13% lower growth rate (p less than 0,05) when compared at similar ME-intakes. As the energy concentration and the growth rate were higher in groups II and III, the feed conversion efficiency and the ME required per kg growth were approximately 30 and 13% lower than that of the control animals. The efficiency of protein utilization of the animals in group III was 4% higher (p greater than 0.05) and the blood urea concentration 20% lower (p less than 0.05) than that in group II. The values for the control animals were intermediate. A similar result was obtained concerning the fat content of the animals. The fat content of the animals in group III was 15.9% and this was significantly lower (p less than 0.001) than that of 21.1% measured in group II. That of the control animals, 18.6%, was not significantly different from the above values. The differences in feeding over the relatively short period of 34 days lead to marked differences in the fatty acid pattern of the backfat. The contents of myristic acid and linoleic acid were significantly different between group II and III; for the former values of 0.8% and 16.9% were determined, respectively, with corresponding values of 48.7 and 11.3% for the latter.(ABSTRACT TRUNCATED AT 400 WORDS)     

Nutritional physiology effect of dietary fats in the diet of growing pigs. 1. Effect of an isocaloric exchange of carbohydrate energy compared with fat energy on protein retention, in vitro synthesis of fat from glucose and on several blood parameters in piglets

Three groups of male, castrated piglets of the German Landrace breed, weight range 3-30 kg, were used to study the relation between fattening performance and blood parameters when feeding rations containing different amounts of fat. The fat content of the rations was either 5% (group I), 18% (group II) or 35% (group III). Concomitantly with the increased metabolizable energy (ME) content of the ration the content of digestible protein (DP) was increased and the amount of feed reduced in order to guarantee an equal intake of ME and DP in all three groups. The digestibility of the crude nutrients and protein retention of the subjects were determined in nine subsequent trials each lasting 7 days. At a body weight of 27 kg the blood concentrations of insulin, glucose, free fatty acids, neutral lipids and cholesterol were determined at different times after feeding. In addition, an oral glucose tolerance test was made and the in-vitro synthesis of fat from glucose was measured. The apparent digestibility of fat amounted, unexpectedly, to approximately 94% on the high rat rations II and III. In all groups a significant positive relation between body weight and digestibility of the fat was determined. Despite equal daily intakes of ME in all groups, in group III daily weight gain and protein retention were 7% (p less than 0.01) and 4% (p less than 0.01) higher than in group I, respectively. Blood urea levels of group III were 67% (p less than 0.01) lower than in group I. The mean daily nitrogen retention of the three groups rose gradually from 4 g at a body weight of 5 kg to 16-17 g at a body weight of 25 kg. The feed conversion of group I was lower by 22 and 36% as compared to groups II and III, respectively. Highly significant differences were observed among either groups (p less than 0.01). It has been calculated that in group III the consumption of ME/kg weight gain was about 8% (p less than 0.05) lower than in the two other groups. According to the increased fat percentage of the rations, body protein content diminished from 17,1% in group I to 16,5 and 16% in groups II and III, respectively. Only the difference between groups I and III proved to be significant (p less than 0.05). In group I feed intake resulted in an increase in the insulin level by 55% (p less than 0.05) whereas glucose did not change significantly.(ABSTRACT TRUNCATED AT 400 WORDS)     

Qualitative and quantitative studies on the metabolism of fatty acids, in particular on that of linoleic acid in calves]

24 calves of the breed "Deutsche Schwarzbunte Rasse" were used for qualitative and quantitative investigations on the metabolism of fatty acids, particularly that of linoleic acid. The trial comprised 6 calves in 4 groups. The experimental rations consisted of powdered skim milk, oat meal, milk sugar, coco fat and varying proportions of linoleic acid (1.0%, 1.5%, 2.5%). The control group received the basal ration without supplements of linoleic acid. After a short period of adjustment the metabolic trial was started with 9 periods each lasting 7 days. The composition of fatty acids in the faecal lipids was analysed by gas chromatography. The studies led to the conclusion that the fatty acids contained in the faecal fat were not immediately derived from the dietary fat. The results of the trial also showed that the major proportion of all the fatty acids present in the faecal lipids consisted of only 4 fatty acids, viz. oleic acid, palmitic acid, lauric acid and myristic acid. Changes observed for the content of linoleic acid in faecal lipids were negligible so that the assumption may be made that all of the linoleic acid added was completely digested.     

Nutrition physiology effects of dietary fats in rations for growing pigs. 5. Effects of soy bean oil and lard on protein retention in piglets

In two experiments with 30 and 26 castrated male pigs of the German Landrace breed, weight range 15-30 kg, the influence of isoenergetic changes in the carbohydrate and fat fractions of the diet were examined. The effect of the addition of soya oil (SO) and lard (LA) to the diet on the utilization of protein and on the blood urea concentration was also examined. The apparent digestibilities of the crude nutrients and energy were determined using different methods. The following were examined: experiment I: ration I (control), ration II (+7% SO), ration III (+7% LA) experiment II: ration I (control), ration II (+2% SO), ration III (+2% SO + 5% LA), ration IV (+7% LA) In all experiments the animals were fed a similar amount of digestible crude protein of constant quality at constant ME-intake. In both experiments the apparent digestibility of crude protein in the groups with 7% added fat was 4% higher (p less than 0,05) than in the corresponding control groups. The apparent digestibility of crude fat in experiment I and II (in groups II and III and in groups III and IV, respectively) was approximately 87%, when calculated on the basis of faecal fat which was determined by a simple ether extract procedure. When the faeces was treated with HCl before determination, these values for experiment I and II were approximately 6% (p less than 0,001) and 1% (NS) lower, respectively. In both experiments the utilization of protein and the blood urea concentration were not significantly influenced by the amount or form of fat included in the rations.     

2种共轭亚油酸异构体对小鼠肌内脂肪沉积和肌肉线粒体代谢的影响

试验旨在研究不同共轭亚油酸异构体对小鼠肌内脂肪沉积和肌肉线粒体代谢的影响.将成长到5周龄的雄性小鼠按体重分成3组(每组8只),适应1周后分别饲喂不添加、添加2％的顺9反11共轭亚油酸(c9,t11-CLA)和添加2％的反10顺12共轭亚油酸(t10,c12-CLA)的日粮,正试期1个月,监测其体重和体组成的变化,饲养试...     

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. 2. The effect of the iodine supplement on nutrient digestibility and on protein and energy retention

Three groups of six pigs each (live weight at the beginning of the experiment 20 kg) were given a cereal ration with 8% rape seed meal. Group I did not receive a J supplement and was fed ad libitum. The rations of groups II and III were supplemented with 1 mg J/kg feed. The feed intake of group II was limited to the amount consumed by group I (pair fed); group III received the feed ad libitum. The daily weight gains of the 3 groups were 327, 377 and 613 g, feed expenditure 3.79, 3.68 and 3.47 kg/kg gain. In an N balance experiment carried out with 3 animals each from groups I and II, 41.4% of the N taken in group I and 43.8% in group II were retained (p greater than 0.05). Liver, intestinal fat and leaf were heavier in group I (p less than 0.01), the protein content of the empty body, the bones and bristles significantly lower than in group II. Protein retention in group II was 14% higher than in group I. In case of iodine deficiency protein retention is lower, energy retention, however, is largely unchanged.     

Development of divergent lines of lean and fat broilers using plasma very low density lipoprotein concentration as selection criterion; results over the fourth generation and lack of effect of dietary fat on performance and carcase fat content

Comparisons were made of the performance and carcase composition of lean and fat broilers from the 4th generation of a breeding experiment which were fed diets containing 25 or 80 g fat/kg. Selection over the 4th generation resulted in continued divergence in the selection trait and the correlated responses of total body lipid and protein contents and the efficiencies of conversion of food and dietary protein. In both lines body weight, efficiency of food utilisation and total body lipid and protein contents were unaffected by dietary fat content. Tissue fatty acid composition was influenced by dietary and genetic factors: dietary fat increased the proportions of linoleic and oleic acids at the expense of palmitic, palmitoleic and stearic acids whilst greater body fatness increased the proportion of palmitoleic at the expense of linoleic acid.     

饲粮中添加黄花蒿乙醇提取物对奶牛产奶性能及乳脂中共轭亚油酸含量的影响

本文旨在研究饲粮中添加黄花蒿乙醇提取物对奶牛产奶性能及乳脂中共轭亚油酸(CLA)含量的影响。试验选取体重(600±29)kg、胎次2~3胎、泌乳期(158±3)d及泌乳量(22.8±1.8)kg/d的泌乳期荷斯坦奶牛15头,采用完全随机区组设计分为3组,每组5头,进行为期40 d的饲养试验,其中1~9 d为预试期,10~40 d为正试期。对照组饲喂基础饲粮,试验1组和试验2组分别在基础饲粮中添加96和160 g/(d·头)的黄花蒿乙醇提取物。结果表明:整个试验期间,2个试验组的产奶量(第24、31和40天)、乳脂率、乳脂产量、乳蛋白率、乳蛋白产量、非脂固形物含量以及乳脂中的饱和脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸、短链脂肪酸、中链脂肪酸和长链脂肪酸含量与对照组相比均无显著差异(P0.05);2个试验组的乳脂中CLA含量分别比对照组提高了30.7%和38.6%,其中试验2组与对照组差异显著(P0.05)。由此得出,饲粮中添加适量的黄花蒿乙醇提取物对奶牛产奶性能没有明显影响,但可以提高其乳脂中CLA含量,从而优化乳脂中脂肪酸的比例。     

Growth and carcass composition of broilers fed sunflower oil and olive oil

Sunflower and olive oils were fed at the same dietary inclusion levels to male broilers as a means of varying the dietary linoleic acid concentration while maintaining similar concentrations of total fat and total unsaturated fatty acids. The type of oil and the dietary supplementation level influenced growth rate, food utilisation and carcass composition. Birds grew faster and utilised food more efficiently when fed the sunflower oil and had higher concentrations of body fat. Increasing the level of supplementation with either oil decreased body fat content. The different responses to the two oils were not related to differences in dietary amino acid balance, ME: protein ratios or rates of food passage through the digestive tract.     

Influence of an omega-3 fatty acid-enriched ration on in vivo responses of horses to endotoxin.

Because certain inflammatory processes are dependent on the fatty acid composition of the cellular membrane, dietary manipulations that replace omega-6 fatty acids with omega-3 fatty acids may modify inflammatory responses. We investigated the effect of supplemental dietary linseed oil, containing the omega-3 fatty acid, alpha-linolenic acid, on in vivo responses of horses to endotoxin. One group of horses (n = 6) was fed a control pelleted ration (0% linseed oil), and another group of horses (n = 6) was fed an 8% linseed oil pelleted ration. After 8 weeks of consuming these rations, all horses were given 0.03 micrograms of Escherichia coli 055:B5 endotoxin/kg of body weight, infused over 30 minutes. Horses were monitored over 24 hours. Compared with baseline values within each ration group, endotoxin infusion caused significant (P less than 0.05) increase in rectal temperature, heart rate, and plasma concentration of thromboxane B2, 6-keto-prostaglandin F1 alpha, and fibrinogen and significant (P less than 0.05) decrease in total WBC count. Compared with baseline values within each ration group, endotoxin infusion failed to cause significant changes in prothrombin, activated partial thromboplastin, thrombin, or whole blood recalcification times, serum concentration of fibrin degradation products, PCV, or plasma total protein concentration. Before and after endotoxin infusion, horses given the linseed oil ration had longer mean whole blood recalcification time and activated partial thromboplastin time than did horses fed the control ration.     

Substitution of protein feed through lysine-supplemented high-protein wheat during the rearing and laying period of hens. 3. Effect of graded lysine doses on the crude nutrient content of carcasses and on the level of amino acids and GOT activity in the blood of young hens]

A large-scale trial was carried out under commercial conditions to investigate to which extent the feeding of rations with varying lysine content to young hens would influence the crude nutrient content of the body fractions and might change the pattern of amino acid composition and the activity of GOT in the blood. Four rations were fed each containing 14.2% crude protein, 626-633 EFh units/kg and 0.59%, 0.61%, 0.54% and 0.46% lysine. The crude protein and crude fat content of the total body and of body fractions were in no case found to be related to the feeding regime. The proportion of crude ash in the "remainder of non-utilizable parts", in "bones", "intestinal and abdominal fat", "ovaries" and "small intestine" decreased with the decreasing lysine content of the rations. The concentrations of free lysine, histidine, arginine, and phenylalanine in the deproteinized blood plasma of the young hens were significantly (a = 0.01) lower in the birds of the lysine deficient group than in the hens of the other groups. Positive regressions were calculated for the lysine content or the content of aspartic acid in the ration and the pattern of free amino acids in blood plasma. Positive and negative linear relationships were found to exist between the concentrations of free lysine, and those of histidine, arginine or threonine, and serine. A close correlation existed between the total amount of essential amino acids in blood plasma and the lysine concentrations of the plasma. Increasing lysine supplementation produced a decline in the N content of the whole blood and blood corpuscles but a rise in the N content of blood plasma. The activity of GOT in the blood of young hens was not found to be useful as an indicator of the quality of dietary proteins.     

Investigations of the influence of the content of plant crude protein in the ration on the utilisation of urea in dairy cattle. 5. 15N-fractions in the blood of lactating cows given 15N-urea intraruminantly

The incorporation of urea-15N (given as an intraruminal drench or infusion) into plasma urea and protein of dairy cows fed isoenergetic rations with different levels of plant protein (9, 11, 12, 14, 15 and 17% in DM) was investigated. A nonlinear and asymptotic dependence between the plasma concentration of urea and protein level in the ration was stated. The availability of dietary urea-15N for plasma urea for 48 hours after administration was lowest in cows fed with low protein rations (9 and 11% of plant protein). On the contrary the highest incorporation of urea-15N into plasma protein of these animals was observed. The possible explanation of these results is presented.     

The substitution of lysine supplemented high protein wheat for protein feeds during the rearing and laying periods of hens. 8. Nitrogen excretion and true amino acid digestibility as an effect of various lysine levels and successive laying periods]

Digestibility trials were performed with laying hens receiving 3 types of rations containing equal proportions of the same dietary components. The percentage of high-protein wheat in these rations was 74%. Ration I was supplemented with 0.12% lysine while 0.06% lysine was added to ration II; ration III remained unsupplemented. The crude protein content of rations 1 to 3 was 16.1%, 16.5% and 16.6%, respectively. The corresponding lysine percentages were 0.66, 0.62 and 0.56. Studies were made to investigate the influence of different lysine levels on the rate of N excretion and various amino acid data. These studies were carried out during two successive laying periods. Only random differences between the data for urinary N excretion and N balances per kg liveweight were obtained in the two laying periods and for the different lysine levels. The true lysine digestibility was significantly lower in the poor-lysine ration as compared with the ration with 0.66% lysine. Moreover, the absorptive capacity for thio-amino acids is influenced by the lysine level of the ration. The proportion of lysine contained in faecal crude protein increased with the decreasing lysine content of the ration. Similarly, the total number of amino acids present in faecal crude protein increased with the declining supply of lysine. These findings suggest that relatively more NPN compounds are excreted in the faeces if adequate amounts of amino acids are supplied rather than when one amino acid is deficient.     

Sugar beet mash silage as a component of a total-mixed-ration for dairy cows--effects on parameters of digestion and animal performance.

Sugar beet mash silage (BMS) was offered in amounts up to 35% of DM to dairy cows as a component of a total-mixed-ration (TMR). Barley and molasses in the control ration were replaced by BMS half in ration BMS 1/2 and in total in ration BMS 1/1 on the basis of the calculated contents of net energy for lactation. Two trials were carried out. In trial I each ration was tested on parameters of rumen fermentation and digestibility of crude nutrients using 4 Holstein cows with rumen fistula. Chewing activity was tested on 2 Holstein cows for each ration. With the BMS rations the ruminal NH3 concentration was lower and the drop in pH was less than in the control ration. The pattern of volatile fatty acids in the rumen fluid from the BMS groups tended towards more propionic and butyric acid. The feeding of BMS showed no negative impact on chewing and rumination. Energy digestibility raised significantly from 59.8% in the control ration to 72.6% in the BMS 1/1 ration. In trial II the same rations were fed in a change-overdesign to a herd of 24 Holstein cows to test feed intake and animal performance. The results showed no significant effects of BMS rations on DM intake and milk production. The results of both trials indicate that even high amounts of cereals can be replaced by BMS without negative effects on rumen fermentation, milk yield and milk composition with slight drop in fat content. For a better handling of BMS, it is of advantage to include it in a TMR.     

Effect of different fat sources on in vitro degradation of nutrients and certain blood parameters in sheep

This study was designed to determine the effects of calcium salt of palm oil fatty acids (CS), hydroxyethylsoyamide (HESA), butylsoyamide (BSA) and soybean oil (SO) on degradation of crude protein and fibre in vitro, and on the blood plasma lipid parameters in vivo. Five mature wethers (body weight 75 kg) were fed five diets in a 5 x 5 Latin square experiment. The control diet consisted of 50% meadow hay and 50% concentrate with no added fat. The control diet was supplemented with CS, HESA, BSA, or SO. Fat was added at 3.5% of dietary dry matter (DM). The final ether extract content of the ration was near 6%. Each period lasted 20 days. Fat supplements, except HESA, consistently decreased the in vitro DM disappearance of soybean meal as compared to control. In contrast to the effect of other treatments, crude protein degradation was greatest in the test tubes with inocula obtained from sheep fed diet with HESA. Fat supplements equally inhibited the DM and fibre breakdown of alfalfa pellet. CS and HESA seemed to be less detrimental to in vitro fermentation of neutral detergent fibre (NDF) than BSA and SO. All fat supplements increased blood plasma triglyceride, cholesterol and total lipid content. Plasma concentration of cholesterol and total lipid was highest with SO. The inclusion of CS in the diet increased 16:0, while all fat supplements increased plasma 18:0 and decreased 16:1 and 18:1 fatty acid content. Plasma 18:2n-6 was not changed by feeding CS and SO. However, compared to the control diet, 18:2n-6 increased with 12 and 41% in plasma fatty acids when sheep were fed HESA and BSA, respectively. The results showed that plasma concentration of linoleic acid was enhanced more when the amide was synthesised from butylamine than when from ethanolamine.     

Fatty acid composition, including conjugated linoleic acid, of intramuscular fat from steers offered grazed grass, grass silage, or concentrate-based diets

The effects of grazed grass, grass silage, or concentrates on fatty acid composition and conjugated linoleic acid (cis-9, trans-11-18:2; CLA) concentrations of i.m. fat of steers fed to achieve similar carcass growth rates were investigated. Fifty steers were divided into 10 blocks based on body weight and assigned at random from within blocks to one of five dietary treatments. The experimental rations offered daily for 85 d preceding slaughter were 1) grass silage for ad libitum intake plus 4 kg of concentrate, 2) 8 kg of concentrate plus 1 kg of hay, 3) 6 kg of grazed grass DM plus 5 kg of concentrate, 4) 12 kg of grazed grass DM plus 2.5 kg concentrate, or 5) 22 kg of grazed grass DM. The concentration of polyunsaturated fatty acids (PUFA) in i.m. fat was higher (P < .05) for steers offered ration 5 than for those given any other ration. Decreasing the proportion of concentrate in the diet, which effectively increased grass intake, caused a linear decrease in the concentration of i.m. saturated fatty acids (SFA) (P < .01) and in the n-6:n-3 PUFA ratio (P < .001) and a linear increase in the PUFA:SFA ratio (P < .01) and the conjugated linoleic acid concentration (P < .001). The data indicate that i.m. fatty acid composition of beef can be improved from a human health perspective by inclusion of grass in the diet.     

Studies on the various sugar-urea and sugar-starch-urea relationships with reference to the fermentation in the rumen and the digestibility of nutrients in fattening cattle]

Recommendations are given saying that sugar-to-crude fibre rations of not more than 1.7:1 and sugar-to-urea ratios of 12:1 should be used in the fattening of cattle fed urea-supplemented rations of roughages in which 40% to 50% of the crude protein content of the ration had been replaced by urea. The amount of sugar per kg live-weight should not exceed 4 g. Higher quantities reduce the digestibility of crude fibre and, additionally, decrease the NH3 level and the pH in the rumen. At the same time the amount of volatile fatty acids is increased while the content of ruminal acetic acid decreases. Variations in the sugar-to-starch ratio had no statistically significant influence on the nitrogen balance whereas it was found that increasing quantities of sugar significantly decreased the digestibility of crude fibre. The proportional content of sugar in the readily metabolisable carbohydrates contained in the ration should not exceed 20% to 50%.     

The influence of dietary linoleic and alpha-linolenic acid on body composition and the activities of key enzymes of hepatic lipogenesis and fatty acid oxidation in mice

We have recently suggested that feeding the C18 polyunsaturated fatty acid, alpha-linolenic acid (ALA), instead of linoleic acid (LA) reduced body fat in mice. However, the difference in body fat did not reach statistical significance, which prompted us to carry out this study using more animals and diets with higher contents of ALA and LA so that the contrast would be greater. The diets contained either 12% (w/w) LA and 3% ALA or 12% ALA and 4% LA. A low-fat diet was used as control. The diets were fed for 35 days. The proportion of body fat was not influenced by the type of dietary fatty acid. Plasma total cholesterol and phospholipids were significantly lower in ALA-fed mice than in mice fed LA. Activities of enzymes in the fatty acid oxidation pathway were significantly raised by these two diets when compared with the control diet. alpha-Linolenic acid vs. LA did not affect fatty acid oxidation enzymes. In mice fed the diet with LA activities of enzymes of de novo fatty acid synthesis were significantly decreased when compared with mice fed the control diet. alpha-Linolenic acid vs. LA feeding did not influence lipogenic enzymes. It is concluded that feeding mice for 35 days with diets either rich in LA or ALA did not significantly influence body composition.     

高温下酶制剂对肉鸭生产性能及能量代谢的影响

选用1日龄樱桃谷肉鸭1600羽,随机分成4组,分别饲喂4种不同处理的日粮,以研究酶制剂在肉鸭日粮中应用效果。对照组饲喂基础日粮不添加酶制剂;试验1组为饲喂基础日粮并添加酶制剂250 g/t;试验2组和3组分别饲喂能量降低250.8 MJ/kg和334.4/kg基础日粮,并添加酶制剂250 g/t。结果表明:在基础日粮和降低能量的日粮中添加酶制剂,均能提高肉鸭日增重,改善饲料转化率和能量消化率。其中,基础日粮中添加酶制剂,能显著提高肉鸭日增重和饲料利用率(P<0.05),能量消化率最高,按毛利润计算,试验组肉鸭收益率分别比对照组提高了7.02%、4.45%和5.26%。