The ability of genetically lean or fat slow-growing chickens to synthesize and store lipids is not altered by the dietary energy source

The increasing use of unconventional feedstuffs in chicken’s diets results in the substitution of starch by lipids as the main dietary energy source. To evaluate the responses of genetically fat or lean chickens to these diets, males of two experimental lines divergently selected for abdominal fat content were fed isocaloric, isonitrogenous diets with either high lipid (80 g/kg), high fiber (64 g/kg) contents (HL), or low lipid (20 g/kg), low fiber (21 g/kg) contents (LL) from 22 to 63 days of age. The diet had no effect on growth performance and did not affect body composition evaluated at 63 days of age. Glycolytic and oxidative energy metabolisms in the liver and glycogen storage in liver and Sartorius muscle at 63 days of age were greater in chicken fed LL diet compared with chicken fed HL diet. In Pectoralis major (PM) muscle, energy metabolisms and glycogen content were not different between diets. There were no dietary-associated differences in lipid contents of the liver, muscles and abdominal fat. However, the percentages of saturated (SFA) and monounsaturated fatty acids (MUFA) in tissue lipids were generally higher, whereas percentages of polyunsaturated fatty acids (PUFA) were lower for diet LL than for diet HL. The fat line had a greater feed intake and average daily gain, but gain to feed ratio was lower in that line compared with the lean line. Fat chickens were heavier than lean chickens at 63 days of age. Their carcass fatness was higher and their muscle yield was lower than those of lean chickens. The oxidative enzyme activities in the liver were lower in the fat line than in the lean line, but line did not affect energy metabolism in muscles. The hepatic glycogen content was not different between lines, whereas glycogen content and glycolytic potential were higher in the PM muscle of fat chickens compared with lean chickens. Lipid contents in the liver, muscles and abdominal fat did not differ between lines, but fat chickens stored less MUFA and more PUFA in abdominal fat and muscles than lean chickens. Except for the fatty acid composition of liver and abdominal fat, no interaction between line and diet was observed. In conclusion, the amount of lipids stored in muscles and fatty tissues by lean or fat chickens did not depend on the dietary energy source.     

Effect of dietary lysine on muscle protein turnover in growing chickens.

Day-old male chickens were fed ad libitum isoenergetic diets containing 20% crude protein but differing in their lysine content (from 6.5 up to 11.3 g/kg). At 3 weeks of age, protein fractional synthesis rates in the pectoralis major muscle were determined using a large dose injection of 120 mumol per kg body weight of L-[4-3H] phenylalanine. Protein gain in the pectoralis major was measured between 19 and 23 days of age. Protein breakdown was obtained by calculating the difference between protein synthesis and deposition. Weight gain varied curvilinearly with dietary lysine intake and was maximum for 11.3 g lysine/kg of diet. In birds fed an adequate lysine intake (10.1-11.3 g/kg) protein fractional synthesis and breakdown rates were 23.6-25.9 and 17.8-19.8%/d respectively. Increasing lysine supplementation in the diet resulted in an impairment of protein fractional breakdown rates. By contrast, protein fractional synthesis rates remained unchanged owing mainly to an improvement in the synthesis efficiency (kRNA), until birds were fed an adequate lysine intake. These data suggest that the growth rate reduction of chickens fed lysine deficient diets was due to alterations in both rates of protein synthesis and breakdown in skeletal muscle. A maximum protein deposition is achieved when kRNA was optimal, ie for a dietary lysine content of about 9 g/kg, a value close to the requirement.     

Lysine reactivity and starch gelatinization in extruded and pelleted canine diets

Fifteen dry adult canine diets (i.e., dinners, extrudates, pellets) were collected from retailers in Wageningen, The Netherlands, and chemically and physically characterized. Quality measurements were lysine O-methylisourea (OMIU) reactivity and starch gelatinization degree (SGD). In general, extruded diets had a higher crude fat and starch content than pellets. Mean values for starch gelatinization were higher in pellets and ranged between 0.78 and 0.91. The mean reactive/total lysine ratio in extrudate samples was about 5–10% higher than in pellet samples, suggesting the presence in commercial diets of about 200 g bound lysine/kg in pellets and 120 g/kg in extrudates with bound lysine levels of canine dinners about 170 g/kg. Variation of analysed nutrients in pellets was larger than in extrudates. Inclusion of animal or vegetable ingredients, and the process variables during extrusion or pelleting, are the likely causative factors for the variation in lysine reactivity and starch gelatinization.     

Effects of dietary amino acid l‐lysine on survival,growth and haemato‐biochemical parameters in Indian catfish,Heteropneustes fossilis (Bloch, 1974), fingerlings

An 8‐week feeding experiment was conducted to estimate the dietary lysine requirement of fingerling Indian catfish, Heteropneustes fossilis (total length = 6.35 ± 1.10 cm; weight = 4.70 ± 0.65 g) by feeding six isonitrogenous (400 g/kg CP) and isocaloric diets (17.90 kJ/g) containing six supplemental lysine levels ranging from 11.0 to 23.5 g/kg (diets I to VI, in incremental steps of 2.5 g/kg). Triplicate groups with 20 fish each were stocked in 75‐L circular continuous flow‐through troughs and fed experimental diets at 4% BW/day twice daily (08:00 and 18:00 h). Maximum live weight gain (304%), best‐feed conversion ratio (FCR, 1.46) and protein efficiency ratio (PER, 1.71) were obtained at 18.5 g/kg dietary lysine, beyond which these values showed a slight declining tendency. Best values for somatic and hematological indices were also obtained at this level. Significantly (p < .05) higher body protein and low carcass moisture and intermediate fat contents were noted in fish fed diets containing 18.5 g/kg lysine. The quadratic regression analyses of live weight gain, FCR, PER and body protein deposition (BPD) data indicated lysine requirements at 19.3, 18.8, 18.6 and 18.6 g/kg of dry diet, respectively. Based on these results, it is recommended that the H. fossilis diet should contain lysine at a level of 19.0 g/kg of dry diet, corresponding to 47.5 g/kg of dietary protein, for optimum growth and efficient feed utilization.     

Lysine requirements of imported European pigs in the humid lowland tropics from 23 to 62 kg liveweight

The responses of 144 Large White × Landrace pigs (72 castrated males and 72 females; mean initial liveweight approximately 23 kg) to graded additions of L-lysine monohydrochloride to a basal diet containing yellow maize and groundnut meal and 180 g crude protein per kg were studied. Total dietary lysine levels ranged from 5–12 g kg^?1. All diets contained digestible energy of 15.44–16.02 MJ kg^?1 DM. The pigs were individually fed from 23 to 33, 47 or 62 kg liveweight. Growth performance, carcass characteristics, nitrogen retention and plasma urea concentration were employed as response criteria. Influence of sex on lysine requirements for optimum growth, nitrogen retention and efficiency of essential amino acids utilization measured by minimum plasma urea concentration was also investigated.Supplementing the basal diet with L-lysine monohydrochloride significantly (P < 0.001) improved growth performance. Castrated male pigs grew faster and responded better to dietary lysine supplementation than gilts. No apparent decline in lysine requirements for optimum growth performance was observed for the two sexes of pigs as they got older. Optimum growth performance in castrated males was obtained with 9, 8 and 8 g lysine kg^?1 diets for the liveweight ranges 23–33, 23–47 and 23–62 kg, respectively. Optimum growth performance of the gilts for all three liveweight ranges was obtained at an estimated dietary lysine concentration of 11 g kg^?1.Optimum lean deposition, carcass leanness and other carcass measurements were obtained at 8 g lysine kg^?1 diet. Carcass data were not analysed for influence of sex.Plasma urea concentration showed further evidence of a quicker and cheaper indirect index of dietary amino acid adequacy in pigs. Minimal plasma urea concentration was obtained at 7–8 g lysine kg^?1 diet for the three liveweight ranges investigated.In a humid tropical environment, such as Ibadan, the dietary lysine requirement of Large White × Landrace pigs of 23–62 kg is about 9 g lysine kg^?1 diet for optimum growth performance and carcass quality, but nitrogen metabolism and plasma urea data suggest a lower level of to 7–9 g lysine kg^?1 diet.     

Plasma arginine and ornithine levels and selected enzyme activities in uremic rats fed various amounts of arginine

Rats weighing 100 g were made chronically uremic by partial left renal artery ligation and contralateral nephrectomy. Rats with urea clearances below 0.30 ml/min and sham-operated controls were pair-fed arginine-free diets, diets containing normal amounts of arginine or diets with high levels of arginine. After 4 to 8 weeks, rats were killed and plasma levels of arginine, ornithine and lysine were measured. In addition, activities of various urea cycle enzymes in liver and kidney and renal transamidinase were determined. Plasma amino acid levels and enzyme activities of the urea cycle remained constant in control rats fed diets differing in arginine content. However, renal transamidinase activity was elevated in control rats fed arginine-free diets. In plasma of uremic as compared with control rats, arginine levels varied with the arginine intake, and lysine levels were elevated when arginine supplements were fed. With all diets, plasma ornithine remained constant in uremic rats at slightly but not significantly increased levels. Hepatic carbamoyl phosphate synthetase activity and renal arginine synthetase activity were reduced in uremic as compared to control rats. Renal transamidinase activity, expressed per g of kidney, was elevated in uremic rats with all diets except arginine-free. When amino acid diets were fed, hepatic arginase activity was higher in uremic rats and this increase was enhanced by arginine-free diets. Other enzyme activities in uremic rats were not affected by the amount of arginine in the diet.     

The responses of rats to various combinations of energy and protein. I. Diets made from purified ingredients

Male and female weanling rats were fed ad libitum for 28 days on purified diets with metabolizable energy levels of 8.0, 9.5, 11.0 or 12.5 MJ/kg and protein:energy ratios of 1:1, 1.33:1, 1.67:1 or 2:1 %:MJ/kg at each energy level. Major nutrients were balanced in proportion to energy and protein. The following parameters were measured: food intake, bodyweight, body length, abdominal fat, liver and kidney weights. Increasing dietary energy level reduced food intake but the reduction was not sufficient to prevent an increase in energy intake. This was reflected by increases in bodyweight, body length, abdominal fat, and relative liver and kidney weights, especially in male rats. Higher energy intake increased weight gain and food conversion efficiency to a greater extent than higher protein intake. The response to protein intake at different energy levels was not consistent. There was no common protein:energy ratio for overall good performance. It is concluded that rat growth and other features can be controlled by the alteration of dietary energy and protein levels.     

Symposium mit internationaler Beteiligung vom 27.-29. Oktober 1981 in Dresden

Two feeding trials were performed on rainbow trout of mean initial weights of 40 and 50 g and lasting for 12 and 14 weeks, respectively. In trial 1, diets contained per kg 300 g fish meal and varying proportions of gelatinized maize starch plus either casein or hydrolyzed feather meal. Dietary crude protein content varied from about 27 to about 53%. In trial 2, all diets had about 45% crude protein. Fish meal (300 g/kg) was replaced in 3 steps by hydrolyzed feather meal either without or with supplementation of L‐ lysine‐HC1 and/or DL‐methionine.

In trial 1, efficiency of utilization of digestible energy (DE) rose from 38 to 50% when the ratio digestible crude protein (DCP)/DE was increased from about 11 to 17 g/MJ irrespective of the source of additional DCP, but did not further increase at higher ratios DCP/DE. Efficiency of utilization of DCP was about 50% as long as the ratio DCP/DE did not exceed 17 g/MJ.

With progressing replacement of fish meal by hydrolyzed feather meal, efficiencies of utilization of DE as well as of DCP were reduced, the respective rates of reduction being about halved by supplementing lysine with no effect of supplementing methionine.     

Supplemental L-arginine improves feed conversion and modulates lipid metabolism in male and female broilers from 29 to 42 days of age

The excessive accumulation of abdominal fat in broilers is an economic waste. Supplemental dietary L-arginine has been shown to reduce lipogenesis in broilers, but studies on this subject are still scarce. Two experiments were conducted in a 5 × 2 factorial design, with five L-arginine concentrations in diets (0, 3, 6, 9 and 12 g/kg) provided to male and female broilers, from 29 to 42 days of age, reared in boxes or cages, with six replicates of 23 broilers per box and six replicates of three broilers per cage, totalling 1560 broilers. Data on performance, carcass and cuts yield, abdominal fat deposition, chemical composition of the breast, lipid profile and liver enzyme activity were evaluated in experiment 1. In experiment 2, the balance and retention of nitrogen, metabolizability coefficients and metabolizable energy of feed were determined and the treatments were evaluated in six replicates of three broilers per cage, totalling 180 broilers. In both experiments, there was no interaction (P > 0.05) between L-arginine concentration in the diet and sex of the broilers for all parameters evaluated. Male broilers showed higher (P < 0.05) weight gain, noble cuts yield, levels of CP and mineral matter in the breast, better feed conversion (P < 0.05) and lower (P < 0.05) malic enzyme activity in the liver and abdominal fat deposition. On the other hand, regardless of sex, the increase in L-arginine concentration in the diet improved (P < 0.05) the feed conversion in addition to reducing (P < 0.05) serum levels of total cholesterol and low-density lipoprotein cholesterol, the malic enzyme activity in the liver and abdominal fat deposition. In conclusion, male broilers had better productive results than females. However, supplementing the diet of male or female broilers from 29 to 42 days of age with L-arginine at a concentration of 6.87 g/kg represents a nutritional strategy to improve feed conversion and reduce circulating triacylglycerol and cholesterol levels, NADPH synthesis by liver malic enzyme and abdominal fat deposition, without negatively affecting the carcass and noble cuts yield, the amount of nitrogen excreted by the broilers and the energy value of the feed.     

Chemical composition and energy content of chickens in response to different levels of dietary polyunsaturated fatty acids

Two experiments were performed to study the effect of dietary polyunsaturated fatty acids (PUFA) on abdominal fat pad weight and chemical composition of broilers. In Experiment 1, different fat sources were blended in different ratios keeping added fat level constant (9%). In Experiment 2, PUFA gradient was obtained by increasing the level of inclusion (2, 4, 6 and 8%) of PUFA-rich oil. The treatments had 15, 34, 45 and 61 and 28, 38, 48 and 59 g PUFA/kg diet, respectively. Apparent metabolizable energy intake was similar in both experiments, except for the more saturated diet in Experiment 1 (15 g PUFA/kg), where it was lower. In Experiment 1, abdominal fat pad weight, total body fat and body energy were lower in the animals on the high PUFA diets (p < 0.05) compared to the animals on the saturated-rich ones, meanwhile in Experiment 2 there were no differences on chemical and energy composition by increasing added PUFA-rich oil inclusion level. In conclusion, PUFA-rich chicken diets, compared to saturated-rich ones, cause a lower body fat deposition, but not compared to low-PUFA low-fat diets.     

Dietary supplementation with maize distillers dried grains with solubles during late gestation and lactation: Effects on sow and litter performance,and on colostrum and milk composition

The objectives of this study were to determine the effects of maize distillers dried grains with solubles (DDGS) during late gestation and lactation on sow and piglet performance, and on colostrum and milk composition. Thirty-six second- and third-parity (2.43 parity) sows (Yorkshire) were allotted to 1 of 3 groups and fed diets containing 0 (control), 200 or 400 g DDGS/kg during the last 20 d of gestation and throughout a 21 d of lactation. Experimental diets contained 12.9 MJ metabolizable energy/kg and 9.7 g lysine/kg. The colostrum and milk samples were obtained on d 0 (farrowing) and d 21 (weaning). There were no differences (P>0.05) in the sows’ average gestation lengths, weaning-to-estrus interval, average daily feed intake, and the lactation backfat and body weight change between dietary treatments. There were no dietary effects (P>0.05) of DDGS on the numbers of total, born alive piglets, average birth weights, piglets per litter at weaning or piglets average daily gain during lactation. No differences (P>0.05) were observed in total solids, protein, fat and lactose among the sows fed the DDGS diets compared with the control. The composition of total solids and protein of sows colostrum and milk were higher at farrowing (d 0) than at weaning (d 21) (P<0.001). However, the fat and lactose content of sows colostrum and milk were increased (P<0.001) from d 0 (farrowing) to d 21 (weaning). In conclusion, the results suggest that 400 g DDGS/kg (87 g lysine/kg) supplemented with 5.2 g lysine/kg included in late gestation and lactation diets is sufficient to replace all the dietary soybean meal without significantly affecting sow and litter performance or colostrum and milk composition.     

Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens

Feeding broilers by alternating different diets for 1 or 2 days is known as sequential feeding, and it possibly reduces leg problems since it slows down early growth and may enhance general activity. The present study compared continuous feeding with a standard diet (C: metabolisable energy = 12.55 MJ/kg, crude protein = 190 g/kg) with alternations of a high-energy/low-protein diet (E+P-:+7% ME; -20% CP) and a low-energy/high-protein diet (E-P+: -7% ME,+20% CP) and investigated its effects on growth, behaviour and gait score in 352 male Ross broiler chickens. Sequential feeding was carried out during ten 48-h sequential-feeding cycles from 8 to 28 days of age. Three treatments were compared: complete diet (C) and two alternations of diets varying in protein and energy contents (S1: E+P- followed by E-P+; and S2: E-P+ followed by E+P-). Chickens received the same feed during the starter and finisher periods (0 to 7 and 29 to 38 days of age). Body weight (BW), feed intake, general activity and gait score, bone quality and carcass conformation were measured to evaluate leg condition and general performance. Sequential feeding significantly reduced BW at 28 days of age (S1: -9.1%; S2: -3.7%/C group; P < 0.05) and S1 were lighter than S2. In both sequential groups, time spent standing increased (C: 28%; S1:33%; S2: 35%; P < 0.05) and leg abnormalities decreased (mean gait score: C: 2.61; S1: 2.45; S2: 2.38; P < 0.02). This improvement was not related to changes in bone quality. BW at slaughter was impaired in Group S1 only, and the feed conversion ratio throughout the rearing period was not significantly impaired by sequential feeding. However, abdominal fat was higher in the S2 group. Sequential feeding using diets varying in energy and crude protein can be a useful method of reducing leg problems in broilers since it improves gait score without impairing growth performance when used as early as 8 days of age and up to not less than 8 days before slaughter in order to compensate for reduced growth. This improvement can be explained by reduced early growth and enhanced motor activity. However, it appears that the low-energy diet should be given first in order to avoid a reduction in BW at slaughter.     

Adipose tissue and the effects of fat and calories on breast tumorigenesis in rats

A high fat diet fed ad libitum will promote breast tumorigenesis in rats while caloric restriction of the same high fat diet counteracts this promotional effect. The present study examined the effects of dietary fat and calorie intake on adipose tissue weight and fatty acid composition and on tumor incidence and development. The sites of adipose tissue chosen were the mammary fat pad, representing adipose tissue in the immediate location of the studied tumor, and the abdominal fat depot which in humans has been associated with an increased risk of breast cancer. High (20% corn oil) and low (5% corn oil) fat test diets were offered ad libitum and at 40% restriction levels. In agreement with prior studies, caloric restriction of both high and low fat diets led to marked decreases in tumor incidence (63 to 68% versus 21%), tumor burden (1.84 to 2.05 versus 0.37 to 0.43 tumors/rat), and tumor weight (7.1 to 11.9 versus 1.4 to 2.2 g) at the time of sacrifice (133 days post-DMBA). While final body weights were reduced in proportion to the level of caloric restriction (290 to 291 g versus 184 to 201 g), abdominal fat (8.8 to 9.2 versus 0.9 to 1.6 g), and mammary fat weights (3.1 to 4.1 versus 0.7 to 2.0 g) were reduced markedly in association with the decrease in tumorigenesis. While both tumor and mammary fat were enriched with linoleate reflecting the fatty acid composition of dietary fat, the ratio of arachidonic acid to linoleic acid was higher in tumor tissue than in surrounding normal mammary tissue in both the phospholipid (0.78 versus 0.18) and neutral lipid fractions (0.22 versus 0.03). These observations are consistent with the concept that increases in fat tissue mass in abdominal and mammary fat depots may mediate some of the promotional effects of high fat and high calorie diets. Restriction of dietary fat and calories to reduce body fat and strategies to modify the composition of stored lipids in fat depots may offer nutritional approaches to breast cancer prevention and treatment.     

Feeding value of field beans (Vicia faba L. var. minor) with and without enzyme containing tannase,pectinase and xylanase activities for broilers

Effects of field beans with various tannin content and exogenous enzyme mixture containing tannase, pectinase and xylanase activities on N-corrected dietary apparent metabolisable energy (AMEn), coefficients of dry matter (DMR) and nitrogen retention (NR), fat digestibility, gastrointestinal tract (GIT) development, jejunal villus morphometry, ileal digesta viscosity and sialic acid were examined. Birds’ growth performance and energy conversion ratio (ECR) were also measured. Birds were fed one of eight mash diets. The Control diet contained as major ingredients wheat (400 g/kg) and soybean meal (SBM) (127 g/kg and 221 g crude protein/kg and 12.83 MJ AMEn/kg. To reduce nutrient density, the Control diet also contained washed sand at 119 g/kg. Another three diets containing 300 g/kg of each of three experimental field bean cultivar samples in replacement for SBM and sand were also mixed. Each diet was fed to nine pens with two male Ross 308 broilers. Diets high in tannin had low AMEn, ECR, DMR and NR (p < 0.001). Feeding field beans increased (p < 0.001) the weights of the pancreas and the proventriculus and gizzard (PG) of the birds. Supplementing diets with the enzyme mixture improved (p < 0.001) feed conversion efficiency, AMEn and all nutrient utilisation coefficients despite the tannins in diets. The enzyme mixture reduced ileal digesta viscosity (p < 0.001) and the weight of pancreas, total GIT and PG (p < 0.05) of the birds. It can be concluded that the feeding value of field beans with different tannin contents may vary when fed to broilers. The supplementation of the enzyme mixture improved the feeding value of diets for broilers. The beneficial effect of the addition of the enzyme mixture seems to be mediated through reduced ileal digesta viscosity and improved nutrient availability.     

Untersuchungen über den Vitamin B2-Bedarf der Legehenne

Because of the well established function of carnitine possible effects of carnitine were studied in poultry. In trial I it was investigated if carnitine and its precursors (lysine, methionine) reduce the formation of abdominal fat in broilers. Chickens (10 groups of 10 chickens each) were fed different diets (control, lysine and methionine in excess and deficient, respectively, with or without 5% fat supplement, L‐carnitine and DL‐carnitine supplement, respectively).Performance (body weight gain, feed conversion), amount of abdominal fat and carnitine concentration in blood, muscles (M. sartorius, M.pectoralis superficialis, cardiac), liver and kidney were determined. Performance and abdominal fat were influenced by dietary fat, lysine and methionine as expected and were not altered by carnitine. Excess and deficiency of lysine and methionine did not influence, fat supplement reduced and carnitine supplementation significantly increased tissue concentration of carnitine.

In trial II it was studied if supplementation of a commercial layers’ ration with either 500 mg L‐carnitine or 500 mg nicotinic acid or both per kg reduces the cholesterol concentration in yolk. Influence on body weight, feed intake, laying performance, serum and yolk cholesterol concentration could not be observed, but yolk concentration of carnitine was significantly increased in supplemented groups.

Trial III should clarify if the L‐carnitine content in broiler parentstock ration influences hatchability. Four groups of 1350 hens each were fed a commercial all‐mash supplemented with 0, 20, 50 and 100 mg L‐carnitine, respectively. Hatching rate was increased from 83% to 87% and from 82.4% to 85.3% in groups supplemented with 50 and 100 mg L‐carnitine, respectively, and in randomly sampled eggs of these groups carnitine concentration in yolk was higher.     

壳聚糖对俄罗斯鲟幼鱼生长性能及免疫功能的影响

在基础饲料中分别添加浓度为0对照组）、1.25、2.5、5、7.5和10 g/kg的壳聚糖,投喂12 g左右的俄罗斯鲟50d,每组设3个重复,每个重复30尾,研究不同浓度的壳聚糖对俄罗斯鲟（Acipenser gueldenstaedti）幼鱼的生长性能及免疫力的影响。结果表明,与对照组相比,添加2.5和5 g/kg的壳聚糖可显著提高俄罗斯鲟幼鱼的增重率和特定生长率,降低饲料系数（P < 0.05）,而当添加量超过10 g/kg时会抑制其生长（P < 0.05）;1.25和2.5 g/kg组血清超氧化物歧化酶活性显著高于对照组（P < 0.05）,其他试验组则显著低于对照组（P < 0.05）;2.5和5 g/kg组溶菌酶活性显著高于对照组,当壳聚糖添加量超过7.5 g/kg时则会抑制血清溶菌酶活性（P < 0.05）;1.25和5 g/kg组酸性磷酸酶活性、碱性磷酸酶活性和补体C3含量都显著高于对照组（P < 0.05）;各试验组IgM含量不受壳聚糖的影响,与对照组差异不显著（P>0.05）。在试验条件下,添加适量的壳聚糖能提高俄罗斯鲟幼鱼的生长性能,增强其免疫能力,以增重率、特定生长率及非特异性免疫为综合评价指标,壳聚糖添加量以2.5 g/kg为宜。     

Effects of increasing amounts of hempseed cake in the diet of dairy cows on the production and composition of milk

This study explored the potential for using seed cake from hemp (Cannabis sativa L.) as a protein feed for dairy cows. The aim was to evaluate the effects of increasing the proportion of hempseed cake (HC) in the diet on milk production and milk composition. Forty Swedish Red dairy cows were involved in a 5-week dose-response feeding trial. The cows were allocated randomly to one of four experimental diets containing on average 494 g/kg of grass silage and 506 g/kg of concentrate on a dry matter (DM) basis. Diets containing 0 g (HC0), 143 g (HC14), 233 g (HC23) or 318 g (HC32) HC/kg DM were achieved by replacing an increasing proportion of compound pellets with cold-pressed HC. Increasing the proportion of HC resulted in dietary crude protein (CP) concentrations ranging from 126 for HC0 to 195 g CP/kg DM for HC32. Further effects on the composition of the diet with increasing proportions of HC were higher fat and NDF and lower starch concentrations. There were no linear or quadratic effects on DM intake, but increasing the proportion of HC in the diet resulted in linear increases in fat and NDF intake, as well as CP intake (P < 0.001), and a linear decrease in starch intake (P < 0.001). The proportion of HC had significant quadratic effects on the yields of milk, energy-corrected milk (ECM) and milk protein, fat and lactose. The curvilinear response of all yield parameters indicated maximum production from cows fed diet HC14. Increasing the proportion of HC resulted in linear decreases in both milk protein and milk fat concentration (P = 0.005 and P = 0.017, respectively), a linear increase in milk urea (P < 0.001), and a linear decrease in CP efficiency (milk protein/CP intake; P < 0.001). In conclusion, the HC14 diet, corresponding to a dietary CP concentration of 157 g/kg DM, resulted in the maximum yields of milk and ECM by dairy cows in this study.     

PERFORMANCE,CARCASS CHARACTERISTICS,MEAT QUALITY AND PLASMA CONSTITUENTS OF MEAT TYPE DRAKES FED DIETS CONTAINING DIFFERENT LEVELS OF LYSINE WITH OR WITHOUT A MICROBIAL PHYTASE

This experiment was conducted to study growth performance, carcass characteristics, meat quality and plasma constituents of Campbell drakes fed diets containing different levels of lysine with or without a microbial phytase. Basal vegetable duck all-mash diets were fed during the growing (1- 35 d of age), and finishing period (36 - 56 d of age) and were formulated to contain 0.90% and 0.73% lysine (negative control), respectively. These diets were supplemented or not with L-lysine HCl, which resulted in a dietary lysine level of 0.90, 0.95, 1.01 and 1.06% and 0.73, 0.80, 0.87 and 0.94%, during the growing and finishing period, respectively. Furthermore, the diets were fed with or without 600 FTU phytase (Natuphos®) except for those containing 1.06 and 0.94% lysine during the growing and finishing period, respectively (positive control). A lysine level of 1.01/0.87% in the growing/finishing diet significantly increased BWG and improved FCR of drakes by 2.1 and 1.8%, respectively. Phytase significantly increased BWG by 2.1% and 3.5% after feeding the basal diet and 1.01/0.87% lysine, respectively. Also, FCR was significantly improved by 2.2 and 1.8% of groups fed 0.95/0.80, and 1.01/0.87% lysine, respectively. Phytase as an independent variable increased BWG by 1.8, and improved FCR by 1.0%. Lysine and/or phytase did not affect carcass yield, and meat quality treats as well as plasma constituents of drakes. However, lysine level at 0.95/0.80% and 1.01/0.87% significantly decreased abdominal fat deposition compared to either the negative or the positive control. In conclusion, a lysine level of 1.01/0.87% in the growing/finishing diets for drakes is adequate. After phytase supplementation of the basal diet the BWG at a lysine level of 0.90/0.73% were similar to the positive control (1.06/0.94% lysine). However, the best FCR was obtained after feeding diets containing 1.01/0.87% lysine supplemented with phytase.