Effect of supplementary choline on the performance of broiler breeders fed on different energy sources

1. Laying performance, egg quality, fertility and hatchability, and fat deposition in liver and abdomen were recorded in broiler breeders (29 to 48 weeks of age) fed on diets containing perarl millet (Pennisetum typhoides) (PM), broken rice (BR) or yellow maize (YM) (600 g/kg diet). Constant ratios of metabolisable energy (ME) to other nutrients were maintained in all the diets. Food grade choline chloride (50%) was added to the diets at 3 concentrations (0, 760 and 1,520 mg/kg). Each diet was offered to 3 replicate groups of 15 birds (12 hens and 3 cockerels), maintained in deep litter pens, to provide 1.46 MJ ME/bird/d. 2. Neither the source of energy nor dietary choline content had any influence on hen-d egg production, fertility or hatchability. Food efficiency and egg weight were significantly reduced in BR-fed groups compared to those fed on the other energy sources. 3. The efficiency of energy and protein utilisation increased and liver fat content was decreased significantly by dietary choline supplementation. 4. Haugh unit score, egg shell weight, liver weight and intestinal weight were not influenced by either supplementary choline or the source of energy. However, the yolk colour index was significantly reduced in PM- or BR-fed groups compared to those fed on the maize-based diet. 5. Deposition of abdominal fat was significantly greater in BR-fed birds compared to those fed on the YM-based diet, while liver fat content was significantly greater in the birds fed on the PM-or BR-based diets than those based on YM. Although supplementation of the diet with choline had no influence on abdominal fat deposition, liver fat content was significantly reduced in birds given diet containing 760 mg supplemental choline/kg diet. 6. The present study indicates that PM or BR can be used as principal energy sources in place of YM in broiler breeder diets without affecting egg production, fertility or hatchability. Liver fat content can be reduced by adding choline at 760 mg/kg to diets based on different energy sources.     

Protein and energy self-selection by turkey hens: reproductive performance

1. The influence of protein and energy self-selection on the reproductive performance of turkey hens was investigated. Large White turkey hens were fed on either a complete diet (185 g CP/kg, 11.30 MJ ME/kg) or were provided with a choice between a high protein-low energy diet (348 g CP/kg, 7.74 MJ ME/kg) and a high energy-low protein diet (81 g CP/kg, 13.39 MJ ME/kg). 2. Egg production, egg weight, and the fertility and hatchability of eggs produced were not significantly affected by the dietary treatments (P greater than 0.05). 3. While energy intake was not significantly different between groups, protein consumption decreased by approximately 40% (P less than or equal to 0.001) among self-selecting hens compared to hens fed on the complete diet. This resulted in a 10% (P less than or equal to 0.05) reduction in the food intake in the self-selecting birds.     

生长猪白酒糟消化能和代谢能的评定及预测模型的建立

本研究旨在评定白酒糟的营养成分及在生长猪上的消化能(DE)和代谢能(ME),并基于其所含化学组分建立白酒糟在生长猪上DE和ME的预测模型。选取78头健康、体重(52.1±3.6)kg的杜×长×大三元杂交去势公猪,随机分配到1个玉米-豆粕型基础日粮和12个白酒糟(替代基础日粮供能组分的30%)待测日粮处理中进行消化代谢试验,每个处理6个重复,每个重复1头猪,用全收粪尿法和套算法测定其对生长猪的DE和ME值。进一步分析每个样品的化学成分与其有效能值的关系,用逐步回归法建立了12个白酒糟样品DE和ME的预测方程。结果表明:饲喂基础下,12个白酒糟样品的DE为3.79~8.81 MJ/kg,ME为3.54~8.15 MJ/kg;白酒槽DE的最佳预测方程为DE(MJ/kg)=38.46-0.63×粗灰分-0.11×粗纤维-1.14×总能-0.03×中性洗涤纤维(R^2=0.81),ME的最佳预测方程为ME(MJ/kg)=41.86-0.75×粗灰分-1.51×总能+0.20×粗脂肪-0.05×粗纤维(R^2=0.74)。     

不同日粮对广西合浦鹅生产性能及养分代谢的影响

本研究旨在探讨不同日粮对鹅生长性能和纤维类物质及其他养分利用能力的影响。选取4周龄、体重相近的广西合浦鹅60只,随机分为3组,每组20只(公母各1/2),分别饲喂3种不同代谢能(ME)水平的日粮:第1组10.03 MJ/kg,第2组11.00 MJ/kg,第3组11.85 MJ/kg,进行42 d的饲养试验;同时分别于5周龄和9周龄时从上述3组试验鹅中各选取4只体重相近的试鹅进行代谢试验并用内源指示剂法(4 mol/L HCl不溶灰分)测定试鹅对日粮养分的代谢率。结果表明:在整个试验期间各组试鹅平均日增重差异不显著(P>0.05);5周龄时,各组日粮养分代谢率差异也不显著(P>0.05);但在9周龄时,第1组的CF、DM和能量代谢率显著高于其余2组(P<0.05或P<0.01)。因此,本试验证明了日粮ME在10.03~11.85 MJ/kg时,不影响合浦鹅的增重和屠宰性能;在9周龄、日粮ME为10.03 MJ/kg时,其CF、DM和能量代谢率显著高于ME为11.00或11.85 MJ/kg组,而高能量日粮并未表现出养分代谢上的优势。     

不同品种小麦生长猪消化能与代谢能预测模型的建立

本试验旨在研究不同品种小麦的理化特性及对生长猪的消化能和代谢能值,并探讨通过理化特性建立消化能与代谢能预测模型的可行性。试验选取12头初始体重相近(50.1±2.8)kg的杜×长×大三元杂交去势公猪,随机分成2组,每组6头猪,采用2个6×6拉丁方设计,试验共6期。采用直接法评定12个小麦样品的能量价值,每个小麦样品配制1种日粮,共12种日粮,小麦在日粮中所占比例为97.0%。结果表明:12个不同品种小麦的能值差异极显著(P<0.05),其中北麦4的消化能含量最低(16.40 MJ/kg DM),而龙麦30的消化能含量最高(17.01 MJ/kg DM)。北麦4的代谢能含量亦最低(15.72 MJ/kg DM),辽春10最高(16.48 MJ/kg DM)。通过回归分析,建立了以总能和理化特性为基础的小麦消化能和代谢能预测模型,推荐预测模型:DE=-829-58.4×ADF+1.1×GE(R2=0.79,RSD=24.5),DE=-1384+1.1×GE+0.65×BW(R2=0.79,RSD=24.8),ME=-2990+1.7×GE-50.2×Xylans-87.6×Ash(R2=0.88,RSD=21.1)。     

Influence of dietary energy, supplemental fat and linoleic acid concentration on performance of laying hens at two ages

1. The aim of this study was to investigate the influence of metabolisable energy (ME), supplemental fat (SFAT) and linoleic acid (LIN) content of the diet on the productive performance and weight of eggs and egg components of Isabrown hens of 22 or 74 weeks of age. 2. Six diets were formulated to contain the following concentrations of ME (MJ/kg), SFAT (g/kg) and LIN (g/kg), respectively: A) 11.8, 0 and 11.5; B) 11.8, 40 and 11.5; C) 11.8, 40 and 16.5; D) 11.2, 40 and 16.5; E) 11.2, 40 and 11.5; and F) 11.2, 0 and 11.5. Data were collected for 28 d and analysed using linear contrasts to test the effect of SFAT, LIN, ME and their interactions. 3. When the LIN content of the diets was maintained constant at 11.5 g/kg, an increase in the SFAT from 0 to 40 g/kg increased egg weight (63.8 vs 64.5 g; P<0.05), food intake (119 vs 124 g; P<0.01) and energy intake (1.36 vs. 1.42 MJ/d; P<0.01) and body weight change of the hens (-85 vs. 27 g; P<0.001). Supplemental fat also increased yolk (15.8 vs. 16.3 g; P<0.001) and albumen weight (40.8 vs. 42.3 g; P<0.01) but yolk to albumen ratio was not modified. 4. Egg and albumen weights were improved by SFAT in early but not in late producing hens. As a result, yolk to albumen ratio decreased in the younger hens, from 0.371 to 0.357, but increased in the older hens, from 0.408 to 0.415; P<0.01) with fat addition. 5. An increase in the LIN content of the diets from 11.5 to 16.5 g/kg did not modify any of the traits studied. 6. It was concluded that the LIN requirement of the hens for maximal productivity and weight of eggs is 11.5 g/kg or less. Supplemental fat increased the weight of eggs and albumen in the younger but not in older hens and the beneficial effect was independent of its LIN content.     

Effect of dietary energy concentration and apparent ileal digestible lysine:metabolizable energy ratio on nitrogen balance and growth performance of young pigs

Two experiments were conducted to determine the optimal apparent ileal digestible lysine:ME (Lys:ME) ratio and the effects of lysine and ME levels on N balance (Exp. 1) and growth performance (Exp. 2) in growing pigs. Diets were designed to contain Lys:ME ratios of 0.6, 0.7, 0.8, and 0.9 g/MJ at 13.5 and 14.5 MJ of ME/kg of diet in a 4 x 2 factorial arrangement. In Exp. 1, conventional N balances were determined on 48 crossbred barrows (synthetic line 990, initial BW = 13.1 +/- 0.7 kg) at approximately 15, 20, and 25 kg of BW with six pigs per diet. At 15 kg of BW, an energy density x Lys:ME ratio interaction on daily N retention was observed (P < 0.05). At each BW, N retention improved with an increase in N intake associated with increasing ME concentration. In 15-kg BW pigs, increasing the Lys:ME ratio increased daily N retention at the 13.5 (linear, P < 0.001) and 14.5 MJ of ME level (linear, P < 0.01; quadratic, P < 0.05). In 20-kg BW pigs, N retention (g/d) increased (linear, P < 0.001; quadratic, P < 0.01) and N retention (percentage) increased (linear, P < 0.001) as the Lys:ME ratio increased. At 25 kg of BW, N retention (g/d) increased quadratically (P < 0.05) with an increase in Lys:ME ratio. The Lys:ME ratios that maximized daily N retention at 15 kg of BW were 0.88 and 0.85 g/MJ at the 13.5 and 14.5 MJ of ME levels, respectively and 0.81 and 0.77 g/MJ (for both ME levels) at 20 and 25 kg of BW, respectively. Over the 28-d trial, an energy density x Lys:ME ratio interaction on ADG was observed (P < 0.05). Increasing energy density increased growth performance, whereas increasing the Lys:ME ratio in high-energy diets increased ADG (linear, P < 0.05; quadratic, P < 0.01) and gain:feed ratio (G/F) quadratically (P < 0.01). Average daily gain and G/F ratio were greatest in pigs fed the 14.5 MJ of ME diet and the Lys:ME ratio of 0.82 g/MJ. In Exp. 2, 128 individually housed crossbred barrows and gilts (initial BW = 12.8 +/- 1.6 kg) were used to determine the effect of diets used in Exp. 1 on growth performance in a 4 x 2 x 2 factorial arrangement. The ME level increased ADG and G/F from d 0 to 14 and from d 0 to 28. Increasing the Lys:ME ratio increased ADG from d 0 to 14, whereas growth performance was maximized in pigs fed Lys:ME ratio of 0.82 g/MJ. These results suggest that pigs from 13 to 20 and from 20 to 30 kg of BW fed diets containing 14.5 MJ of ME/kg had maximum N retention and ADG at 0.85 and 0.77 g of apparent ileal digestible lysine/MJ of ME, respectively.     

Net energy of oat bran,wheat bran,and palm kernel expellers fed to growing pigs using indirect calorimetry

The objectives of this experiment were to (a) determine the effects of fiber increase in diets on heat production (HP), (b) determine the net energy (NE) of oat bran (OB), wheat bran (WB), and palm kernel expellers (PKE) fed to growing pigs using indirect calorimetry (IC). Twenty‐four growing barrows (29.2 ± 2.6 kg) were randomly allotted to one of four diets with six replicate pigs per diet. Diets included a corn‐soybean meal basal diet and three test diets containing 30% OB, WB or PKE, respectively. During each period, pigs were individually housed in metabolism crates for 20 days, including 14 days to adapt to the diets. On day (d) 15, pigs were transferred to the open‐circuit respiration chambers for determination of daily total HP and were fed one of the four diets at 2.3MJ ME/kg body weight (BW)^0.6/day. Total feces and urine were collected for the determination of digestible energy (DE) and metabolizable energy (ME) and daily total HP was measured from d 15 to d 19 and fasted on day 20 for the measurement of fasting heat production (FHP). The apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), and organic matter (OM) were greater (p < 0.01) in pigs fed the basal diet compared with those fed the test diets. The ATTD of neutral detergent fiber (NDF) was lower (p < 0.01) in pigs fed the WB diet compared with those fed the basal, OB, or PKE diets. The ATTD of ether extract (EE) in pigs fed the PKE diet was greater (p < 0.01) compared with those fed the other diets. The average total HP and FHP in pigs fed the four diets were 1261 and 787 kJ/kg BW^0.6/d, respectively, and were not significantly affected by diet characteristics. The NE:ME ratio for diets ranged from 78.1 to 80.9%. The NE contents of OB, WB, and PKE were 10.93, 7.47, and 8.71 MJ/kg DM, respectively.     

花生秧作为肉用绵羊单一粗饲料有效能值的测定与估测

本试验旨在用套算法和插值法测定与估测肉用绵羊花生秧有效能值,确定替代法中饲粮中适宜花生秧替代比例,为单一秸秆饲料有效能值的测定与估测提供方法学上的参考。选用体重为(45.00±1.96)kg的体况良好的杜泊×小尾寒羊F1肉用成年羯羊54只,采用随机区组设计,分为9组,饲粮分别为基础饲粮、全花生秧饲粮和分别以10%、20%、30%、40%、50%、60%、70%花生秧替代基础饲粮的试验饲粮,每组6个重复,每个重复1只羊。预试期10 d,正试期9 d,其中气体代谢试验3 d,消化代谢试验6 d。结果表明:1)全花生秧饲粮组花生秧干物质(DM)表观消化率与20%、30%、40%组间差异不显著(P0.05),显著高于其他各组(P0.05)。全花生秧饲粮组花生秧有机物(OM)表观消化率与20%组差异不显著(P0.05),但显著高于其他各组(P0.05)。全花生秧饲粮组花生秧总能(GE)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、粗脂肪(EE)表观消化率显著高于10%组(P0.05),粗蛋白质(CP)表观消化率显著低于10%组(P0.05),与其他各组间差异不显著(P0.05)。2)花生秧消化能(DE)、代谢能(ME)均具有相同的规律,即全花生秧饲粮组DE、ME(8.57、6.69 MJ/kg DM)与20%(8.22、6.58 M J/kg DM)、30%(8.02、6.50 M J/kg DM)、40%组(8.10、6.52 M J/kg DM)差异不显著(P0.05),但显著高于其他组(P0.05)。3)插值法求得花生秧M E"真值"为6.62 M J/kg DM,接近于套算法得到的花生秧ME。综合得出,套算法可以用于肉用绵羊估测花生秧(单一粗饲料)的DE和M E;用套算法测定花生秧秸秆类粗饲料有效能值,其在饲粮中的适宜替代比例为20%~40%。     

饲粮不同代谢能、粗蛋白质水平对新杨绿壳蛋鸡产蛋后期生产性能、蛋品质及血清生化指标的影响

本试验旨在通过研究饲粮不同代谢能、粗蛋白质水平对新杨绿壳蛋鸡产蛋后期(44~56周龄)生产性能、蛋品质及血清生化指标的影响,得出其产蛋后期饲粮代谢能和粗蛋白质的适宜配比。选取768羽体重相近的43周龄末新杨绿壳蛋鸡,随机分为6组,每组4个重复,每个重复32羽。采用2×3因子(代谢能水平为10.87和11.08 MJ/kg,粗蛋白质水平为15.00%、15.50%和16.00%)设计试验,共设计6种饲粮。试验预试期1周,正试期12周。结果表明:1)饲粮不同代谢能、粗蛋白质水平对绿壳蛋鸡产蛋后期产蛋率和料蛋比有显著影响(P0.05),饲粮代谢能和粗蛋白质水平在产蛋率上表现出极显著的交互作用(P0.01),其中,高能低蛋组(代谢能为11.08 MJ/kg,粗蛋白质为15.00%)产蛋率最高,料蛋比最低。2)饲粮较高粗蛋白质水平(16.00%)能显著提高绿壳蛋鸡产蛋后期鸡蛋的哈氏单位(P0.05);饲粮较高代谢能水平(11.08 MJ/kg)能显著提高绿壳蛋鸡产蛋后期鸡蛋的蛋黄颜色(P0.05);饲粮代谢能和粗蛋白质水平在蛋品质上未表现出显著的交互作用(P0.05)。3)高能低蛋组绿壳蛋鸡血清尿素氮含量最低;饲粮较高代谢能水平(11.08 MJ/kg)能显著降低绿壳蛋鸡血清总胆固醇含量(P0.05)。综上,在本试验条件下,饲粮代谢能、粗蛋白质水平分别为11.08 MJ/kg和15.00%时,更有利于绿壳蛋鸡产蛋后期生产性能的发挥和蛋品质的改善。     

不同代谢能和粗蛋白质水平对合浦鹅日粮养分消化率及生长性能的影响

本文旨在研究日粮不同代谢能和粗蛋白质水平对合浦鹅日粮干物质、粗蛋白质、粗脂肪、粗纤维、钙和磷等养分的消化率及生长性能的影响.将120只28日龄的合浦鹅随机分成6个组,进行2个饲养和消化试验:试验1组饲喂粗蛋白质水平为15.10%,代谢能水平分别为10.03、11.00和11.85 MJ/kg的3种日粮;试验2组饲喂代谢能水平为11.50 MJ/kg,粗蛋白质水平分别为12.50%、14.85%和17.83%的3种日粮.用4 mol/L HCI ALA方法测定日粮的养分消化率.结果表明:粗蛋白质水平为15.10%和代谢能水平为10.03 MJ/kg的日粮,具有较高的养分消化率,但不同代谢能水平对试鹅的生长性能影响差异不显著(P>0.05);代谢能水平为11.50 MJ/kg和粗蛋白质水平为12.50%的日粮也具有较高的养分消化率,但不同粗蛋白质水平对试鹅的生长性能影响差异也不显著(P>0.05).因此,28日龄以后的合浦鹅的日粮粗蛋白质和代谢能水平分别为15.10%和10.03 MJ/kg,或分别为12.50%和11.50 MJ/kg时,均具有较高的养分消化率,但对合浦鹅的生长性能无显著影响.     

Food intake and abdominal adipose tissue in White Leghorn hens fed diets of different protein and energy concentrations

1. Single Comb White Leghorn hens of 2 ages (44 and 80 weeks) were fed diets of different energy (10.88, 12.13 or 13.39 MJ ME and 140 g protein/kg) or protein (120, 140, 160 or 180 g and 12.13 MJ ME/kg) concentration over an 8-week period. 2. Food intake did not change with increasing concentrations of dietary protein. Protein intake was directly correlated with dietary protein concentration. 3. Energy intake increased with dietary energy concentration but, generally, failed to match the increases in dietary energy concentration. Energy, rather than protein, concentration was the major determinant of food intake. 4. Efficiency of energy utilisation decreased and mean adipocyte size increased with higher energy intake. 5. A bimodal adipocyte size distribution, consisting of a primary large size and a secondary small size population, was present in the abdominal fat pad of birds of both ages. There was no significant difference in the numbers of large adipocytes between the hens of the two ages. 6. The greater mean fat pad weight in the older hens was associated with increased mean cell volume in the population of large adipocytes.     

Food intake of the laying hen following crop loads of maize oil and other nutrients

The metabolisable energy (ME) of the diet of laying hens at an ambient temperature (Ta) of 20 degrees C was abruptly changed from 10.9 MJ/kg to 12.9 MJ/kg, or vice versa. Food intake during the next 14 d was significantly reduced by the low ME diet and was increased by the high ME diet, that is, the expected compensatory changes in food intake did not occur. Laying hens given the same change of diet as above but kept at 32 degrees C did not show any change in food intake within 14 d. Thus ME intake increased with the high ME diet and decreased with the low ME diet. Daily doses of 10 ml maize oil/kg body weight given directly into the crop of laying hens at a Ta of 20 degrees C, resulted in an immediate, significant, reduction of food intake such that total ME intake remained the same as with normal feeding. Daily doses of 3 ml maize oil/kg, given as before, resulted in an immediate, significant, reduction in food intake at a Ta of 20 degrees C but at a Ta of 32 degrees C food intake remained unchanged; consequently daily ME intake increased. Loading the crop with glucose or sucrose, at Ta 20 degrees C, in quantities which provided a similar ME as 3 ml maize oil/kg, reduced food intake but the adjustment was less precise and daily ME intake increased. Loading with glycerol or protein hydrolysate decreased both food and ME intake. Crop loads of starch were as effective as maize oil in bringing about a significant and compensatory reduction of food intake. Similar volumes of water or liquid paraffin placed in the crop did not affect food or ME intake. A similar weight or cellulose placed in the crop reduced food and ME intake.     

青稞、荞麦、黍子、糜子、莜麦对于生长猪的营养价值评定

本研究旨在对青稞、荞麦、黍子、糜子和莜麦5种可在生长猪上应用的非常规谷物饲料原料进行营养价值评定。试验分别采集5种谷物原料样品,选取36头健康、体重为(32.1±4.2)kg的杜×长×大三元杂交去势公猪,随机分配到1个玉米-豆粕型基础日粮和5个非常规谷物饲料原料(替代基础日粮的40%～50%)的待测日粮处理中进行消化代谢试验,用全收粪尿法和套算法测定其对生长猪的全肠道表观消化能、代谢能以及总能和营养物质的表观全肠道消化率。结果表明:黍子、糜子有较高的淀粉含量,青稞和莜麦有较高的中性洗涤纤维和酸性洗涤纤维含量;干物质基础下,5种谷物原料的全肠道表观消化能和代谢能分别为15.97～17.87 MJ/kg和15.38～17.34 MJ/kg。     

Effect of inclusion of sugar beet pulp,pelleting and season on laying hen performance

1. The effect of three metabolisable energy (ME) concentrations 12.2, 11.3 and 10.5 MJ ME/kg and two forms of diet (mash and pellet) on egg production in summer and winter were studied. The different ME values were obtained by diluting the 12.2 MJ ME/kg diet with sugar beet pulp of 2.88 MJ/kg DM. In a 3rd summer experiment the water intake of hens on these diets was examined. Data were analysed by factorial analysis of variance, and the relationship between performance and dietary energy concentration was examined by regression analysis.

2. The use of low energy diets (10.5 to 11.3 MJ ME/kg) decreased egg production in both seasons, but pelleting diets improved egg production and egg weight in summer. Egg weight was not affected by energy density in winter, but decreased in the summer when energy density increased.

3. In winter, food consumption was not affected by the dietary ME, while in summer food consumption increased when the dietary ME increased. Therefore, energy intake was not the same at all energy densities, but tended to increase as the energy density increased.

4. In summer, pelleting improved food efficiency and egg production and increased water consumption and the ratio of water to food intake. Water intake and water: food ratio decreased with increasing dietary energy concentration.     

Effect of the gut microflora on chick growth and utilisation of protein and energy at different concentrations of dietary protein

The effect of the gut flora on chick growth and protein and energy utilisation at a marginal dietary energy level (calculated metabolisable energy value 11.7 MJ/kg) was determined with diets containing 227 or 293 g protein/kg. Germ-free (GF) and conventional (CV) chicks were reared for 10 d on the diets, and excreta were collected during the last 4 d. The chicks were killed and carcases and droppings were analysed for N and fat. The GF chicks grew significantly faster than the CV controls on both diets. The growth of CV chicks given the high protein diet was similar to that of GF chicks given the adequate protein diet. Protein and energy utilisation were significantly less for CV than for GF chicks on both diets. It was concluded that the energy requirement of CV chicks was greater than that of their GF counterparts, and that their poorer growth was due to utilisation of some dietary protein as an energy source.     

Effects of dietary metabolisable energy, calcium and phosphorus on bone mineralisation, leg weakness and performance of broiler chickens

1. Performance, gait score (GS), tibial dyschondroplasia (TD), and tibia bone mineralisation and breaking strength were determined in 2880 male and female Ross 208 broilers fed on diets with two different concentrations of dietary metabolisable energy (ME) (11.00 or 12.00 MJ/kg) and 4 different concentrations of available phosphorus (aP) adjusted for dietary ME content (4.0, 4.5, 5.0 or 5.5 g/kg aP in starter and 3.5, 4.0, 4.5 or 5.0 g/kg aP in finisher diets containing 12.00 MJ/kg). 2. Tibia ash, calcium (Ca) and phosphorus (P) contents in broilers given diets with low ME (11.00 MJ/kg) were greater than those of broilers given diets with higher ME (12.00 MJ/kg). Tibia ash, Ca and P contents increased curvilinearly with increasing dietary aP content. The dietary aP level had no effect on GS. 3. Dietary concentration of ME or aP had no effect on tibia breaking strength. 4. Walking ability, as measured by GS, was negatively correlated with the body weight (BW) of tested birds at 23 and 35 d of age, but the dietary ME content or aP level had no significant effect on GS at 35 d of age. 5. The results indicated that bone mineral content had no clear correlation with the walking ability of broilers.     

The effects of dietary energy concentration on growth rate and conversion of energy to weight gain in broiler chickens

Eight diets, their metabolisable energy (ME) concentrations ranging from 2.3 Mcal/kg to 3.6 Mcal/kg (9.6 to 14.1 MJ/kg) were fed to each of four pens of broilers in two trials. Food intake was inversely related to energy concentration but the ME required by each sex to reach a given live‐weight was quite similar. Birds on the diets with a medium energy concentration (about 3.1 Mcal/kg (13.0MJ/ kg)) required slightly less ME than those on other diets and generally reached the required live‐weight earlier than those on other diets. Birds in the first trial required less of any particular diet than their counterparts in the second trial, reflecting the lower ambient temperatures recorded during the latter trial. Mortality recorded from 14 d of each trial was generally lower for birds on the medium energy concentration diets and dressed carcass percentage higher than those on other diets.

The results of the present study are in agreement with the recent recommendation (National Research Council, 1971) of 3.2 Mcal ME/kg (13.4 MJ/kg) for broiler diets. However, it is suggested that minimum and maximum values be given in such recommendations; this would allow greater flexibility and a wider range of ingredients in diet formulation.     

Effects of increasing the fibre content of a layer diet

The fibre content of a basal diet fed to laying hens was increased from 149.2 g to between 218.6 and 292.3 g/kg by the inclusion of various fibrous farm wastes and by-products at 200 g/kg diet. The fibrous ingredients lowered the metabolisable energy (ME) of the basal diet from 11.82 to between 9.31 and 11.21 MJ/kg. Utilisation (g food/kg egg) of the basal diet was not significantly different from values for diets containing maize cob, cassava or maize starch residues. The diet containing maize cob supported a performance similar to that of the basal diet, despite a lower energy content (10.08 MJ/kg). Diets containing cowpea shell, cassava peel or sawdust, with lower energy contents, and those containing maize starch residue, palm kernel meal or dried brewers grains, with higher energy contents, were not as good. The diet containing cassava starch residue supported similar egg production to the basal but egg size was less. Inclusion of some of the fibre sources caused slight decreases in yolk cholesterol, although this could not be correlated with dietary fibre content. Additional dietary fibre caused slight increases in gizzard weight but this was also not simply related to dietary fibre content.     

饲料代谢能水平对农大3号小型蛋鸡生产性能的影响

180只140日龄的农大3号小型蛋鸡随机平均分为A、B、C、D、E五组,每组6个重复,每个重复6只鸡,体重大小基本一致,各组间生产性能差异不显著。分别饲喂代谢能水平11.5MJ/kg、11.3MJ/kg、11.1MJ/kg、10.9MJ/kg和10.7MJ/kg的饲料,其他营养成分含量设计上保持一致。通过30周的观察,发现在产蛋高峰前饲喂稍低能值的饲料(10.9MJ/kg)有利于采食量的增加和产蛋率的迅速上升。在一定饲料代谢能值范围内,饲料能值的高低对小型蛋鸡采食量影响不显著,所以从产蛋高峰期开始,必须使用代谢能水平较高的日粮,才能满足小型蛋鸡维持高产蛋率对能量的需求。综合来看,饲料代谢能为11.3MJ/kg时,小型蛋鸡有较高的产蛋量和饲料报酬。