Effect of dietary ascorbic acid supplementation level on productivity,mortality, and carcass characteristics of Venda chickens

Two experiments were carried out to determine the effect of dietary ascorbic acid supplementation levels on productivity, carcass characteristics, and mortality of indigenous Venda chickens. The first experiment determined the effect of dietary ascorbic acid supplementation levels on productivity and mortality rate of 175 unsexed Venda chickens between 1 and 6 weeks old. The second experiment determined the effect of dietary ascorbic acid supplementation levels on productivity, carcass characteristics, and mortality rate of 140 female Venda chickens between 8 and 13 weeks old. A completely randomized design was used in both experiments. Supplementation of grower diets with ascorbic acid ranged from 0 to 2,000 mg per kg DM feed in both experiments. Levels of ascorbic acid supplementation for optimum feed intake, feed conversion ratio, growth rate, live weight, and breast meat yield were determined using a quadratic equation. The optimal dietary ascorbic acid supplementation levels for feed conversion ratio, growth rate, and live weight of Venda chickens during the starter phase were 1,050, 1,301, and 1,500 mg/kg DM feed, while, at the grower phase, the optimal supplementation levels for feed conversion ratio, growth rate, live weight, and breast meat yield were 1,000, 1,250, 1,482, and 769 mg/kg DM feed, respectively. Results indicate that different levels of ascorbic acid supplementation optimized feed conversion ratio, growth rate, and live weight of Venda chickens at each growth phase. However, levels of ascorbic acid supplementation for optimum feed conversion ratio, growth rate, and live weight were higher than that for breast meat yield. These findings have implications on ration formulation for Venda chickens.     

Effects of glycine and glutamine supplementation to reduced crude protein diets on growth performance and carcass characteristics of male broilers during a 41-day production period

Glycine has been reported to be conditionally essential for broilers fed reduced crude protein diets during the starter period. Research evaluating dietary Gly responses subsequent to the starter period is sparse. This experiment was conducted to ascertain the effects of feeding reduced crude protein diets supplemented with Gly and/or L-Gln (nitrogen source) on growth performance and carcass characteristics of broilers during a 41-day production period. Eight dietary treatments were utilized with the negative control diets formulated to contain approximately 2.4 and 0.29% points lower crude protein and total Gly + Ser concentrations, respectively, than the positive control diets. The 6 other diets were formulated to contain intermediate concentrations of total Gly + Ser and/or crude protein (nitrogen) by adding Gly and/or L-Gln, respectively, to the negative control diets. Glycine appeared to have more pronounced effects than nitrogen contribution on feed conversion ratio and body weight gain of broilers during starter and grower periods, whereas Gln improved feed conversion of broilers in the finisher period. Total breast meat weight and yield of broilers provided diets with the additions of Gly and L-Gln were higher than those receiving diets with only Gly or L-Gln supplementation. The positive outcomes on growth performance and carcass characteristics suggested that providing adequate total Gly + Ser and nitrogen concentrations in diet formulation may be necessary for broilers when dietary CP content was reduced approximately by 2.4% points during a 6-week production period.     

Beneficial Effects of Versazyme,a Keratinase Feed Additive,on Body Weight,Feed Conversion,and Breast Yield of Broiler Chickens

Versazyme (VZ) is a keratinase-based feed additive. Broiler diets were formulated with low (95%), medium (100%), or high (105%) CP and amino acid levels relative to US Poultry Industry Reporting Service averages (2003). In each diet, amino acid minimums were maintained relative to the percentage of CP. The protein levels were as follows: starter—21, 22, 23%; grower—19, 20, 21%; finisher—17, 18, 19%; and withdrawal—16, 17, 18%. Mixed sex broilers 0 to 48 d of age were fed the 3 protein levels with and without VZ (0.10%) in a 3 × 2 factorial experiment. Statistical main effects indicated 48-d BW was greater on the high protein diets (2.42 kg) compared with low protein (2.36 kg), with the medium protein diet being intermediate (2.40 kg). Overall, VZ significantly (P < 0.01) improved 48-d BW 2.54% (from 2.36 to 2.42 kg, P < 0.01), feed conversion ratio 1.62% (from 1.912 to 1.881, P < 0.01), and breast meat yield 1.68% (from 31.57 to 32.10%, P < 0.01). The improvements in BW and feed conversion ratio by VZ were greatest with the low protein diets. However, VZ produced the greatest improvement in breast meat yield at the medium and high protein levels. This enzyme feed additive apparently improves the utilization of amino acids by broilers fed diets formulated to commercial specifications.     

Effect of dietary digestible lysine level on growth performance,blood metabolites and meat quality of broilers 23–38 days of age

This study was done to evaluate the effects of different dietary digestible lysine (dig Lys) levels on growth performance, blood metabolites, carcass and breast yield, and breast meat quality of broilers 23–38 days of age. Three hundred 23-day-old Cobb-500 male broiler chickens were allocated to a completely randomized design with five treatments (finisher diet containing 0.88%, 0.94%, 1.00%, 1.06% and 1.12% dig Lys) and six replicates of 10 birds each. Feed intake (FI) was not affected by different dietary dig Lys levels. Weight gain (WG) linearly increased and feed conversion ratio (FCR) linearly decreased with an increasing dietary dig Lys levels. With increasing dietary dig Lys levels, carcass and breast yield and breast meat hue angle (h^*) linearly increased, but abdominal fat decreased quadratically, whereas breast meat lightness (L^*) and ether extract composition linearly decreased. Dietary dig Lys levels did not show any significant effect on serum metabolites, breast meat cooking loss and water holding capacity. Based on the linear broken-line regression models, the weight gain, feed conversion ratio and breast yield were optimized when dietary dig Lys levels were 0.95%, 1.01% and 1.02% respectively. It is concluded that Lys requirements vary according to what productive parameter is taken for optimization. A minimum of 1.02% dig Lys concentration in the finisher diet is suggested to optimize breast yield, feed efficiency and performance in broiler chickens.     

Nutritional value of quality protein maize and food corn for starter and growth pigs

Growth traits with starter and grower pigs and a digestion trial were conducted to compare the nutritional value of Quality Protein Maize (QPM), food corn and conventional feed corn. The QPM, food and feed corn contained .45, .31 and .29% lysine, respectively. The growth trials evaluated a QPM-soybean meal diet formulated on a lysine basis (.96% in starter and .7% in grower diets) and four diets arranged in a 2 (food corn vs feed corn) X 2 (low vs high soybean meal) factorial. Soybean meal was either added in the same amount as in the QPM diet or was added to provide the lysine content of the QPM diet. Performance was similar for pigs fed food corn and feed corn in both trials. The QPM diets resulted in greater performance than food and feed corn diets containing the same level of soybean meal supplementation; starter pigs were more (P less than .10) efficient and grower pigs had a higher (P less than .01) rate and efficiency of gain. However, performance of pigs fed the QPM diets was not equal to that of pigs fed isolysinic food and feed corn diets; growth rate was lower (P less than .05) in starter pigs and gain:feed was lower (P less than .05) in grower pigs. Diets in the digestion trial consisted of the corns plus 3.25% casein. Energy digestibility was similar for all diets. Ileal N and amino acid digestibilities were highest for QPM, intermediate for food corn and lowest for feed corn. In most instances, these differences were significant (P less than .05). Apparent biological value was highest (P less than .05) for QPM. These trials indicate that food corn and feed corn have similar nutritional value, and that starter and grower pigs can benefit from the higher protein quality of QPM.     

Growth Performance,Meat Yield,and Economic Responses of Broilers Provided Diets Varying in Amino Acid Density from Thirty-Six to Fifty-Nine Days of Age

Providing broilers diets formulated to a high amino acid density early in life improves subsequent growth performance and meat yield. Diets formulated to high amino acid concentrations beyond 5 wk of age may increase breast meat yield but may not be economically justified. This study examined growth, meat yield, and economic responses of broilers provided diets varying in amino acid density from 36 to 59 d of age. Birds were given a 4-phase feeding program: starter (1 to 17 d), grower (18 to 35 d), withdrawal-1 (WD1; 36 to 47 d), and withdrawal-2 (WD2; 48 to 59 d of age). All birds were fed a common, high amino acid density diet to 35 d of age (HH). Broilers were provided diets characterized as being high (H), moderate (M), or low (L) in amino acid density for the WD1 and WD2 periods. Dietary treatments were HHHH, HHHM, HHHL, HHMM, HHML, and HHLL from d 1 to 59, with H, M, and L representing the diets fed during each of the 4 periods (starter, grower, WD1 and WD2).Cumulative feed conversion was improved when the HHHH feeding regimen was fed, whereas other final live performance measurements were not affected. Decreasing amino acid density (HHLL and HHHL) limited yields of breast fillets, tenders, and total white meat when compared with the HHHH regimen. As amino acid density decreased from HHHH to HHHM, HHMM, and HHML, carcass yield and breast meat yield were not affected. In general, providing the HHHH feeding regimen increased economic gross feeding margin compared with the other dietary treatments.     

Effect of apparent ileal digestible lysine to energy ratio on performance of finishing pigs at different dietary metabolizable energy levels

A study with a total of 96 crossbred barrows and gilts fed ad libitum in a body weight range of 56-110 kg was carried out in order to investigate whether the optimum ratio of apparent ileal digestible lysine : energy (ME) depends on the energy density of the diet. Dietary treatments were ratios of 0.34, 0.42, 0.50 and 0.58 g digestible lysine/MJ ME either at an energy density of 13 or 14 MJ ME. Body weight gain as well as feed and ME conversion rate were improved when lysine : ME ratio increased from 0.34 to 0.50, whereby all parameters showed a significant ratio x sex interaction. Feed intake and feed conversion rate were higher at a dietary energy density of 13 MJ ME than at an energy density of 14 MJ ME but energy density did not influence daily growth rate, ME intake and ME conversion rate. Fat area above eye muscle and meat : fat ratio were lower and eye muscle area and lean percentage were higher at a ratio of 0.42 compared with a ratio of 0.34. Daily feed intake, body weight gain, feed conversion rate and parameters of fatness were higher in barrows than in gilts. Conversely, gilts had higher eye muscle area and lean percentage. Optimum ratio for body weight gain, feed and ME conversion rate calculated by exponential regression analysis were 0.42-0.43 in barrows. In gilts, feed and ME conversion rate were optimized at a ratio of 0.53 and 0.54. Because growth showed a linear response to increasing digestible lysine : ME ratios, optimum ratio for daily gain in gilts is considered to be at least 0.58.     

Growth performance,carcass characteristics,meat quality and serum profile of broiler chicks fed on housefly maggot meal as a replacement of soybean meal

A study was conducted to invesstigate the housefly maggot meal (HMM) as an alternative protein source to replace the soybean meal in broiler chick's diet. A total of 720 1-day-old male broiler chicks were divided into three groups and fed diets formulated with HMM to replace soybean meal at the rate of 0%, 4% and 8%. The study lasted for 42 days in two phases. Results showed that HMM addition did not markedly affect body weight, average daily body weight gain and average daily feed intake of the broiler chicks. Feed conversion ratio increased linearly (1–21 days) in starter or quadratically (22–42 days) in the grower phase. HMM non-significantly increased the feed intake and body weight during the grower phase. Slight changes were observed for decrease of blood biochemical indices in the platelets (day 21), and alkaline phosphatase and lysozyme (day 42), and increase for red blood cells, packed cell volume, total protein and uric acid on day 42; however, the fluctuations were within the physiological range. Non-significant effects were observed for carcass composition and meat quality, except that HMM numerically reduced the shear force of breast muscle (linear, p = .058). These results are the strong evidence that HMM can be used as an alternative protein source at 8% in broiler chick's diet without any adverse effect on chick's performance.     

Effects of dietary protein and energy concentrations on performance and carcase characteristics of chukar partridge (Alectoris chukar) raised in captivity

1. This study was conducted to determine the effects of starter and grower diets with differing crude protein (CP) and metabolisable energy (ME) concentrations on the body weight (BW), live weight gain (LWG), feed consumption (FC), feed conversion ratio (FCR), and carcase, breast+back, rump, wing, neck and abdominal fat weights of chukar partridge raised in captivity. 2. Chukar partridges were fed on starter diets containing 4 concentrations of CP (160, 200, 240, 280 g/kg) and 4 concentrations of ME (10.9, 11.7, 12.6, 13.4 MJ/kg) from hatch to 8 weeks of age; they were fed on grower diets containing 4 concentrations of CP (150, 175, 200, 225 g/kg) and 4 concentrations of ME (11.9, 12.6, 13.2, 13.8 MJ/kg) from 9 to 16 weeks of age. All diets contained at least 5.5 g/kg methionine, 15 g/kg lysine and 10 g/kg methionine+cystine. Sixteen starter and 16 grower diets were arranged in a 4 x 4 factorial design with 4 levels of CP and 4 levels of ME. Each treatment was replicated three times with each replicate consisting of 5 males and 5 females. 3. Partridges fed on a starter diet containing 160 g CP/kg were significantly lighter at 8 weeks of age than those in groups given diets containing a higher CP. However, at 16 weeks of age, the differences in BW among treatments had disappeared. Throughout, there were no significant effects of ME concentration on BW and LWG. 4. The daily mean FC for the 0 to 8 week and 0 to 16 week periods was not affected by dietary CP concentration. For the 9 to 16 week period, the partridges fed on a grower diet containing 225 g CP/kg consumed more feed than those given a diet containing 175 g CP/kg. 5. The highest FCR for the 0 to 8 week period was in partridges fed on a starter diet containing 160 g CP/kg. For the 9 to 16 week period, the lowest FCR was in partridges fed on a grower diet containing 150 g CP/kg. For the 0 to 16 week period, there was not a significant effect of dietary CP concentration on FCR. The daily mean FC and the FCR for the 0 to 8, 9 to 16 and 0 to 16 week periods decreased when the ME concentration of the starter and grower diets increased. 6. The carcase, rump and breast+back weights of the male partridges increased when the ME content of the diets increased. Weights of all carcase components of the male partridges were significantly greater than those of the carcase components of the females. 7. There were no significant interactions between CP and ME concentrations on BW, LWG, FC, FCR and carcase characteristics. 8. We conclude that the starter diet for chukar partridges raised for meat production should contain at least 200 g CP/kg, 11.7 MJ ME/kg, and the grower diet should contain 150 g CP/kg, 12.6 MJ ME/kg.     

Growth and meat yield responses of Ross × Ross 708 male broilers fed diets formulated with distillers dried grains with solubles varying in ether extract content and inclusion rate from 1 to 49 days of age

An experiment was conducted to evaluate the effects of diets containing low-, moderate-, or high-oil dried distillers dried grains with solubles (DDGS) included at conventional- or increased-inclusion rates fed to 1,500 Ross × Ross 708 male broilers that were assigned to 60 floor pens from 1 to 49 d of age. Three sources of DDGS had ether extract composition of 6.06, 8.80, or 11.59%, on dry matter (DM) basis, representing low-oil, moderate-oil, or high-oil DDGS, respectively. Diets were formulated to contain corn, soybean meal, animal protein meal as the primary ingredients, and 1 of the 3 DDGS sources at either 5, 7, 9, or 11% (conventional-inclusion rate) and 8, 10, 12, or 14% (increased-inclusion rate) in the starter (1 to 14 d), grower (15 to 24 d), finisher 1 (25 to 34 d), and finisher 2 (35 to 49 d) periods, respectively. Apparent ME_n (low-oil:1,975, moderate-oil: 2,644, and high-oil: 3,137 kcal/kg) and digestible amino acid (AA) values of the 3 DDGS sources were determined from previous research. No differences were detected for cumulative BW gain and feed conversion 1 to 49 d of age or meat yields at 50 d of age. Feeding broilers diets containing the low-oil DDGS source increased feed cost per BW gain and breast meat weight of $0.025/kg and $0.004/kg compared with birds fed diets containing high-oil DDGS or moderate-oil and high-oil DDGS sources, respectively. These data indicated that DDGS source and inclusion rate did not affect cumulative growth and carcass characteristics of broilers from 1 to 50 d of age but demonstrate differences in feed cost/BW gain and feed cost/breast meat weight.     

Digestible lysine requirement of starter and grower pigs

Three experiments were conducted to determine the digestible lysine requirement of starter (6 kg BW initially) and of grower (21 kg BW initially) pigs. Experiment 1 used 294 starter pigs and lasted 28 d; Exp. 2 used 182 grower pigs and lasted 35 d. Protein and total lysine contents of the basal corn-peanut meal diets were 20 and .8% for Exp. 1 and 16 and .54% for Exp. 2. Basal diets were fortified with five incremental additions of lysine.HCl to provide lysine contents ranging from .8 to 1.3% in Exp. 1, and .54 to .94% in Exp. 2. Diets contained crystalline tryptophan, threonine and isoleucine (Exp. 1 only) to provide dietary concentrations equal to 18, 70 and 60% of the highest lysine level fed. Average daily gain and gain/feed of both starter and grower pigs increased (P less than .05) linearly and quadratically as dietary lysine level increased. For starter pigs, ADG and gain/feed were optimized at 1.1 to 1.2% total lysine. For grower pigs, ADG and gain/feed were optimized at .86% total lysine. In Exp. 3, barrows fitted with an ileal T-cannula were used in a 4 X 4 Latin square design. Basal diets and diets with added lysine were evaluated. Apparent lysine digestibility of the basal starter and grower diets and lysine.HCl were 79.9, 74.1 and 96.7%, respectively. Based on these values and the total lysine contents found to optimize performance, the digestible lysine requirements of starter and grower pigs are 1.03 and .71%, respectively.     

低蛋白质补充合成氨基酸饲粮对肉仔鸡生长性能、氮排泄及胴体品质的影响

本研究分2个试验,旨在探讨低蛋白质补充合成氨基酸饲粮对肉仔鸡生长性能、氮排泄和胴体品质的影响.试验1选用600只1日龄爱拔益加肉仔鸡(公母各占1/2),分1～21 d,22～42 d和43～49 d 3个阶段饲养,饲粮共设5个处理,粗蛋白质水平分别为:生长前期(1～21 d):22.8%、21.9%、21.0%、19.5%和19.0%;生长中期(22～42 d):20.1%、18.8%、17.8%、16.5%和16.0%;生长后期(43～49 d):18.0%、16.9%、15.9%、15.0%和13.8%.各个处理蛋氨酸、赖氨酸和苏氨酸水平均满足NRC(1994)肉仔鸡营养需要.试验2的5组肉鸡饲粮的蛋白质水平与试验1的生长前期和生长中期饲粮相同,同时补充了足够的合成氨基酸以满足肉仔鸡对所有可消化必需氨基酸的需要量.结果表明:降低饲粮粗蛋白质水平同时补充合成氨基酸不影响试验1各个阶段肉仔鸡的生长性能(P>0.05).当以可消化氨基酸为基础配制饲粮时(试验2),生长前期肉仔鸡的日增重和饲料转化效率得到显著改善(P<0.01),但生长中期和生长全期肉仔鸡日增重和饲料转化效率差异不显著(P>0.05).降低饲粮粗蛋白质水平线性增加了试验1中肉仔鸡的脂肪沉积率(P<0.05),但对其他胴体指标没有显著影响(P>0.05).氮排泄随饲粮粗蛋白质水平的降低而线性减少(P<0.01).此外,降低饲粮粗蛋白质水平还降低了试验2中肉仔鸡血浆甘氨酸和苯丙氨酸的含量(P<0.05).综上所述,降低肉仔鸡饲粮粗蛋白质水平同时补充合成氨基酸可获得使用高蛋白质饲粮时的生长性能和胴体品质.     

Evaluation of supplementary stevia (Stevia rebaudiana,bertoni) leaves and stevioside in broiler diets: effects on feed intake,nutrient metabolism,blood parameters and growth performance

A perennial schrub, stevia, and its extracts are used as a natural sweetener and have been shown to possess antimicrobial properties. Stevia contains high levels of sweetening glycosides including stevioside which is thought to possess antimicrobial and antifungal properties. Little is known about the nutritional value of the schrub in livestock. This study determined the potential use of the shrub as a prebiotic animal feed supplement in light of the recent ban on the use of antibiotics in animal feed and the role of its constituent stevioside in the effects of the shrub. Male Cobb broiler chicks were fed a basal broiler diet without antibiotic but with performance enhancing enzyme mix (positive control), a basal diet without antibiotic and enzymes (negative control), or diets in which 2% of the negative control diet was replaced with either dried ground stevia leaves or 130 ppm pure stevioside during 2 week starter and 2 week grower periods. Body weight gains, feed conversion, abdominal fat deposition, plasma hormone and metabolites and caecal short chain fatty acids (SCFA) were measured in the broilers at 2 and 4 weeks of age. There was no significant effect of the treatments on feed intake during the starter period but birds fed diet supplemented with stevia leaves and stevioside consumed more feed (p < 0.05) than those fed the positive control diet during the grower period. Weight gain by birds fed the positive control and stevioside diets was higher (p < 0.05) than those fed other diets only during the starter period. Feed/gain ratio of birds fed the positive control and stevioside diets was superior (p < 0.05) to others. There was no effect of the treatments on nutrient retention and water content of the excreta. Dietary stevia leave and stevioside decreased total concentration of SCFA and changed their profile in the ceca. There was no effect of the treatments on pancreas weight. Dietary stevia reduced blood levels of glucose, triglycerides and triiodothyronine (T₃) but had no effect on non-esterified fatty acids. In contrast, stevioside only decreased T₃. Both the stevia leaves and stevioside diets significantly increased abdominal fat content. It is concluded that dietary enzyme growth promoters are beneficial to the broilers only during the starter stage and that inclusion of stevia leaves or stevioside has no beneficial effect on the performance of broilers.     

The feeding of ad libitum dietary protein to organic growing-finishing pigs

The effects of three dietary protein levels on growth, meat, and carcass traits were studied in organic pigs fed a three-phase diet. Assuming lysine was the first limiting amino acid, feeds were formulated to ileal digestible (ID) lysine content, with the ID lysine:crude protein ratio set at a constant of 4%. Feeds were also formulated to an isocaloric rate (net energy: 9.4 MJ/kg during the first feeding phase, 9.25 MJ/kg during the second feeding phase and 9.1 MJ/kg during the finisher phase), with a high (HP), a medium (MP) or a low (LP) protein content ranging from 20% to 14% crude protein (CP). ID lysine content of the LP and MP feed was, respectively, 80% and 90% of the ID lysine content of the HP feed. The nutrient formulation of the HP feed was similar to nutrient levels commonly used in conventional Belgian pig farming. From 20 to 40 kg liveweight, the pigs showed better feed conversion ratios, with an increasing dietary protein concentration (r(2)=0.84). This effect was not observed in the second and third phases, although a significant effect of protein concentration on voluntary feed intake in the second phase did occur (P=0.018), probably as a compensation for the lower protein concentration in the LP diet. Analysis of the carcasses showed a lower meat percentage with lower protein concentration (P<0.05), whereas influences on meat quality were limited. It was concluded that whereas during the first phase of growth, higher protein concentration leads to better performance, from the second phase onwards (45 kg), at least with isocaloric diets, a decrease in protein content (corresponding to a 10% reduction in dietary ID lysine levels compared to conventional pig fattening) may be used in organic growing-finishing pig nutrition.     

不同净能水平的低蛋白日粮对猪生长性能和养分消化率的影响

选取120头22kg左右的杜×长×大三元杂交健康生长猪,随机分成5个处理,每个处理6个重复,每个重复4头,探讨低蛋白不同净能水平(10.54、10.28、9.96、9.63、9.45MJ/kg)日粮对生长猪生长性能和养分消化率的影响。结果表明:日粮蛋白降低4个百分点,不同净能处理间的采食量和饲料转化率没有显著差异(P>0.05),日增重随净能的下降呈线性增加,以9.45MJ/kg组最高(P<0.05);养分消化率中,除钙的消化率外,其余养分的消化率均随净能水平的增加而线性下降(P<0.05)。降低净能水平后,血清赖氨酸含量线性增加(P=0.03),对其余氨基酸影响差异不显著(P>0.05);对血清尿素氮含量的影响不显著(P>0.05)。由此可得出,低蛋白日粮中净能水平的降低并不影响生长猪的生长性能和养分消化率。     

Effect of dietary protein content on growth and body composition of fast and slow feathering broiler chickens

1. Broilers were produced from two lines of breeders selected for three generations for fast and slow feather growth. The base population foundation stock originated from a commercial pedigree female line, which carried only the dominant sex‐linked late feathering gene K. Three isoenergetic (12.7 MJ AME/kg) starter and grower diets were formulated to contain 280, 240 and 200, and 260, 220 and 180 g/kg protein, respectively, and fed to 156 broilers of each sex to give three starter‐grower combinations.

2. Broiler performance in terms of growth, food conversion ratio, carcase meat, fat and protein content was optimised on the 240 to 220 g/kg protein starter‐grower series of diets.

3. Birds of the slow line were significantly (P<0.05) heavier at 48 d of age and had the same food intake and food conversion ratio as birds of the fast feathering line.

4. The slow line birds had significantly (P<0.01) shorter feathers and less total plumage weight at 48 d. The slow line birds had significantly (P<0.001) less carcase fat and significantly (P<0.05) more carcase protein than the fast line. The slow line had significantly more carcase meat (P<0.01) within which a greater breast meat yield was evident (P<0.001).     

Whole pearl millet feeding does not impair performance and nutrient digestibility in 28-day-old broiler chickens

The effects of varying inclusion levels of whole grain millet in millet–soya bean-based diets on growth performance, gizzard development, digesta characteristics and nutrient digestion in broiler chicken were investigated. Starter (0–14 days) and grower (15–28 days) broiler chicken diets containing pearl millet at 500 and 540 g/kg diet, respectively, were formulated. The diets comprised of 0%, 20%, 40%, 60%, 80% and 100% of millet incorporated as whole grain. One-day-old unsexed Arbor Acres Plus chicks (n = 540) were allotted to the experimental diets in a completely randomized design with the diets and water provided ad libitum for 28 days. Each treatment was replicated seven times, and each replicate had 12 chicks. Results showed that daily live weight gain and feed conversion ratio of chickens on the whole millet grain diets compared favourably with chicken on the control in both starter and grower phases, while feed intake reduced quadratically (p < .05) with increased whole grain millet levels in the starter phase. Morphological and structural characteristics of the gizzard and small intestine and intestinal digesta pH and viscosity were also unaffected (p > .05) by whole grain millet inclusion levels. However, the weight of intact millet grain in gizzard increased linearly (p < .001) with whole grain millet inclusion in the diets. Dietary whole grain millet inclusion also consistently lowered (p < .05) jejunal and ileal maltase and sucrase activities, but did not influence (p > .05) pancreatic amylase activity. Ileal crude protein and starch digestibility increased, while ileal energy digestibility decreased significantly (p < .05) with whole grain millet inclusion. Whole grain millet inclusion in broiler starter and grower diets up to 500–540 g/kg did not negatively impact on broiler chicken performance.     

Guanidinoacetic acid supplementation is favourable to broiler diets even containing poultry by-product meal

ABSTRACT

1. Two consecutive trials were conducted to evaluate the effects of guanidinoacetic acid (GAA) supplementation (a creatine precursor) and energy levels in broiler diets based on maize-soybean meal (Trial 1) or that additionally included poultry by-product meal (PBPM; Trial 2) on growth performance, carcass yield and breast meat quality to 41 days of age.

2. A total of 792, one-day-old male Ross 308 broiler chickens were randomly distributed into six treatments – three energy levels (sufficient AME_n or 0.2 and 0.4 MJ/kg reduced AME_n) and two GAA levels (0.00% or 0.06%) with eight replicates for each trial.

3. Reducing dietary energy resulted in poorer body weight gain (BWG) and feed conversion ratios (FCR) for each trial (P < 0.05). However, GAA supplementation improved FCR, BWG and European Production Efficiency Factor (EPEF) (P < 0.05).

4. Dietary energy level and GAA addition had no significant effect on carcass parameters, drip loss, pH and chemical composition of breast meat (P > 0.05), but decreased relative liver weight (P < 0.05).

5. It was concluded that, regardless of dietary energy levels, supplementation of GAA to plant-based diets or those including PBPM has the potential to improve growth performance in broilers.     

Lysine requirement of growing male Pekin ducks

1. One growth experiment and one balance test were conducted to study the response to increasing levels of dietary lysine supplementation in male Pekin ducks with special reference to the growth periods from 1 to 3 weeks and 4 to 7 weeks of age. 2. Two different low-lysine diets were used as basal diets in both periods. The basal lysine levels were 7.6 g/kg (d 1 to 21) and 6.2 g/kg (d 22 to 49) and the ranges in lysine concentration were 7.6 to 12.6 g/kg (d 1 to 21) and 6.2 to 11.2 g/kg (d 22 to 49). 3. Growth performance, feed conversion efficiency and meat yield increased ( P < 0.05) with increas6 ing lysine concentration (requirement defined as 95% of the asymptote). 4. It is concluded that the dietary lysine concentration should be 0.93 g/MJ nitrogen corrected apparent metabolisable energy (AME N ) (11.7 g/kg) for the starter period (until d 21) and 0.75 g/MJ AME N (10.0 g/kg) for the grower period (from d 22 onwards).     

Lysine requirements of Korean native ducklings for three weeks after hatch

Dietary lysine content in poultry diets is critical to improve feed utilization efficiency, body protein deposition rate, and carcass traits of growing and finishing poultry. The objective of the current study was to estimate the optimum digestible lysine requirements for maximum growth performance, efficient utilization of nitrogen, and carcass traits of male Korean native ducklings for 3 wk after hatch. A total of 720 one-day-old male Korean native ducklings were used in a completely randomized design having 8 dietary treatments to provide a range of digestible lysine content from 0.44 to 1.07%. Ducklings were randomly allotted to 24 floor pens (6 replicates per treatment and 15 ducklings per pen) and were offered the respective diets on an ad libitum basis for the period of study. Body weight and feed intake were measured weekly to calculate feed conversion ratio. At the termination of the experiment, 2 ducklings per pen were euthanized via cervical dislocation to weigh empty body and drumsticks. The digestible lysine requirement was determined by taking a mean value after fitting the data to both linear-plateau and quadratic-plateau models. Digestible lysine requirements for Korean native ducklings for 3 wk after hatch were estimated to be 0.71, 0.74, 0.65 and 1.01% for maximum body weight, daily gain, and daily feed intake, and for minimum feed conversion ratio, respectively.