Threonine requirement of White Pekin ducks from hatch to 21 d of age

1. A dose-response experiment with 5 dietary threonine concentrations (5.0, 5.8, 6.6, 7.4 and 8.2 g/kg) was conducted to estimate the threonine requirement of White Pekin ducks from hatch to 21 d of age.

2. A total of 240 one-d-old male White Pekin ducks were allotted to 5 experimental treatments and each treatment contained 6 replicate pens with 8 ducks per pen. Ducks were reared in raised wire-floor pens from hatch to 21 d of age. At 21 d of age, growth performance and intestinal morphology were determined.

3. The weight gain and feed intake of Pekin ducks increased and feed/gain of these birds decreased linearly or quadratically as dietary threonine increased from 5.0 to 8.2 g threonine/kg. Compared to ducks fed on diets containing 5.0 g threonine/kg, ducks given diets containing 7.4 g threonine/kg had higher villus height in duodenum, jejunum and ileum.

4. The threonine requirements for weight gain of White Pekin ducks from hatch to 21 d of age was estimated to be 6.72 g/kg when dietary crude protein concentration was 189.8 g/kg and threonine supply was critical for maintaining intestinal structure of these birds.     

Riboflavin requirements of white Pekin ducks from hatch to 21 d of age

1. A 2 × 8 factorial experiment containing different sexes (female and male) and 8 dietary riboflavin concentrations (1.2, 3.2, 5.2, 7.2, 9.2, 11.2, 13.2 and 15.2 mg/kg) was conducted to evaluate the riboflavin requirements of male and female White Pekin ducks from hatch to 21 d of age.

2. A total of 640 1-d-old Pekin ducks including 320 male and 320 female birds were randomly distributed into 80 wire-floor pens of 8 birds, sexed separately and with each treatment group containing 5 replicate pens. The birds were raised from hatch to 21 d of age. At 21 d of age, the weight gain, feed intake, feed conversion ratio and plasma and liver riboflavin were measured.

3. Growth depression, high mortality and low plasma and liver riboflavin were observed in riboflavin-deficient ducks, and these ill effects could be reduced by increasing dietary riboflavin concentrations. Weight gain, feed intake and riboflavin concentration in plasma and liver increased as dietary riboflavin increased.

4. According to broken-line regression analysis, the riboflavin requirements of modern breed of White Pekin ducks from hatch to 21 d of age for weight gain, feed conversion ratio, plasma riboflavin and liver riboflavin were 3.31, 5.20, 3.85 and 3.91 mg/kg for male and 3.27, 3.33, 3.84 and 3.28 mg/kg for female, respectively. Compared with female birds, more riboflavin was needed by male ducks, which may be because of significantly greater weight gain and liver riboflavin content of male ducks.     

Threonine supplementation reduces dietary protein and improves lipid metabolism in Pekin ducks

1. This study was conducted to investigate the efficiency of threonine (Thr) supplementation on reducing dietary crude protein (CP) content and the effects of Thr on lipid metabolism in Pekin ducks. The effects of dietary CP concentration (160, 190 and 220 g/kg) and Thr supplemental concentration (0, 0.7, 1.4, 2.1 and 2.8 g/kg) on growth performance, carcass, liver lipid and plasma profiles were determined in Pekin ducks from 1–21 d of age.

2. A total of 720-d-old male Pekin ducks were randomly allotted to 1 of 15 dietary treatments with 6 replicate cages of 8 birds per cage for each treatment according to average body weight.

3. Dietary Thr supplementation improved growth performance and breast muscle percentage at all CP diets, and ducks fed Thr-supplemented diets had higher plasma concentrations of some plasma amino acids. Thr supplementation reduced the concentrations of total lipid, triglyceride, cholesterol in liver, and plasma low density lipoprotein cholesterin concentration at 160 and 190 g/kg CP, whereas it increased triglyceride concentration at 160 g/kg CP.

4. Thr requirements based on quadratic broken-line model estimation were 6.6 and 7.0 g/kg for optimal average daily gain (ADG), and 6.7 and 7.3 g/kg for breast muscle percentage of Pekin ducks from 1–21 d of age at 190 and 220 g/kg CP, respectively. The dietary Thr requirements and estimated ADG (55.18 vs. 55.86 g/d/bird) and breast muscle percentage (2.79% vs. 2.75%) of Pekin ducks did not differ between 190 and 220 g/kg CP according to the t-test results.

5. Dietary CP level could be reduced to 190 g/kg in Pekin ducks from 1–21 d of age with Thr supplementation to balance dietary amino acids, and Thr supplementation prevented excess liver lipid deposition in this instance.     

Effects of dietary probiotic supplementation on LXRα and CYP7α1 gene expression,liver enzyme activities and fat metabolism in ducks

1. The objective of this study was to investigate the effects of dietary probiotic supplementation on liver X receptor alpha (LXRα) and cholesterol 7α-hydroxylase (CYP7α1) mRNA levels, protein enzymatic activities and fat metabolism in Cherry Valley Pekin ducks.

2. A total of 750 one-day-old Cherry Valley Pekin ducks were randomly divided into 5 groups with three replicates of 50 ducks each in a completely randomised experiment. Each group was fed on a basal diet supplemented with 0, 500, 1000, 1500 or 2000 mg probiotics/kg.

3. Body rate and feed conversion ratio were highest and abdominal subcutaneous fat % was lowest at 1000 mg probiotic/kg.

4. The mRNA levels of LXRα and CYP7α1 in liver tissue was estimated by RT-PCR; serum triglyceride (TG) and total cholesterol (TC) concentrations were measured by ELISA.

5. The expression levels and enzyme activity of LXRα and CYP7α1 increased in conjunction with decreases in TG and TC concentrations following probiotic supplementation to a maximum at 1000 mg probiotics/kg and decreased thereafter.

6. It is concluded that dietary probiotics can enhance LXRα and CYP7α1 enzyme activities in the liver and reduce lipid concentrations and fat deposition in ducks.     

The choline and sulphur amino acid requirements of broiler chickens fed on semi‐purified diets

1. Growth and food conversion efficiency of broilers were reduced at low dietary choline concentrations. These effects were accentuated by low dietary total sulphur amino acids (TSAA).

2. Increased mortality, perosis and other pathological changes involving a number of tissues were observed in birds fed on a low‐choline diet.

3. Methionine replaced part of the dietary requirement for choline at low dietary choline concentrations.

4. High dietary concentrations of choline (> 1 750 mg/kg) increased the requirement for dietary TSAA.

5. Increasing the dietary choline while maintaining the TSAA at an inadequate level may decrease performance.     

Effects of linseed oil and palm oil on growth performance,tibia fatty acid and biomarkers of bone metabolism in broilers

1. This study was conducted to determine the effects of different dietary fat sources on growth performance, tibia fatty acids and biomarkers of bone metabolism in broilers.

2. One-d-old commercial Arbor Acres broilers were fed with a maize–soya bean basal diet for 42 d, supplemented with oils according to the following 5 treatments: lard (lard group); linseed oil (linseed oil group); palm oil (palm oil group); linseed oil + palm oil (60:40 or 40:60 w/w, LP-1 group and LP-2 group, respectively).

3. No significant differences in weight gain, feed intake and gain/feed ratio were observed between the lard and linseed oil groups. Birds fed on palm oil had significantly greater weight gain and feed intake than those fed on lard or linseed oil. Growth performance in LP-1 and LP-2 was significantly greater than that of single-oil groups.

4. Tibia growth and bone characteristics were not influenced by supplementation with lard, linseed oil, or palm oil alone, but broilers fed on a mixture of fats had significantly greater tibia weight and length compared to broilers fed on linseed oil. Bone mineral density in tibia was significantly increased in LP-1 and LP-2 groups.

5. Supplementation of linseed oil alone or in combination with palm oil enhanced apparent digestibility of calcium, reduced serum calcium and increased tibia calcium concentrations. Moreover, supplementation with linseed oil alone or in combination with palm oil had a positive effect on biomarkers of bone growth.

6. The combination of linseed and palm oils was beneficial for growth performance, tibia growth and biomarkers of bone metabolism.     

Influence of ascorbic acid on the adverse effect of feeding a diet containing excess tyrosine to chicks

1. The effects of dietary or parenteral administration of ascorbic acid on the adverse effects of excess dietary tyrosine were investigated with young male White Leghorn chicks in a 2‐week experiment.

2. Addition of 10 g ascorbic acid/kg to the control diet (without excess tyrosine) produced no beneficial effects on performance. Excess dietary tyrosine caused depressions in all measures of performance.

3. Adding 0.1, 1, 10 or 20 g ascorbic acid/kg to the diet containing excess tyrosine tended to improve performance.

4. Subcutaneous injection of 50 mg ascorbic acid/bird d to chicks receiving excess tyrosine brought about a significant improvement in body‐weight gain.

5. The elevation of plasma free tyrosine caused by excess dietary tyrosine decreased as dietary ascorbic acid increased.

6. Ascorbic acid can alleviate, though not completely counteract, the adverse effect of excess dietary tyrosine.     

The growth and carcass characteristics of crosses between Aabio and Tegal ducks and Muscovy and Pekin drakes

1. The growth and food utilisation of Pekin, Alabio and crosses between Muscovy or Pekin drakes and Alabio or Tegal ducks were recorded up to 20 weeks of age on a high plane of nutrition. Ducks were killed at 6, 10 and 16 weeks of age for carcass analysis.

2. The weight of Alabio ducks at 12 weeks of age was increased by 40 and 48% by crossing with Muscovy and Pekin respectively. Pekin crosses grew faster to 8 or 12 weeks of age than Muscovy crosses but after 17 weeks of age there was no significant difference in weight. Food utilisation for Muscovy crosses was generally better at all ages.

3. Both at a given age and per unit of carcass weight, Muscovy crosses contained less fat and as a consequence more protein and ash, and a higher proportion of breast meat than Pekin crosses. Proportion of fat in Muscovy × Tegal ducks increased only slightly with carcass weight, while it decreased in Muscovy × Alabio ducks.     

Increased iron level in phytase-supplemented diets reduces performance and nutrient utilisation in broiler chickens

1. The effect of different levels of dietary iron on phytase activity and its subsequent effect on broiler performance were investigated in a 3 × 2 factorial arrangement. A total of 360 day-old Ross 308 male broiler chicks were distributed to 6 experimental diets, formulated with three levels of Fe (60, 80 and 100 mg/kg) and two levels of phytase (0 and 500 FTU/kg).

2. Phytase supplemented to mid-Fe diets increased feed consumption more than the non-supplemented diet at d 24. From hatch to d 35, Fe × phytase interaction significantly influenced the feed intake (FI), body weight gain (BWG) and feed conversion ratio (FCR). The high-Fe diet supplemented with phytase significantly reduced FI and BWG of broilers than those supplemented with low- or mid-Fe diets. The overall FCR was significantly better in birds fed on the mid-Fe diets with phytase supplementation.

3. A significant improvement in ileal digestibility of N, P, Mg and Fe was observed in birds feed diets containing 60 mg Fe/kg, with significant interaction between Fe and phytase.

4. Phytase improved the bone breaking strength when supplemented to low- or mid-Fe diets, compared to the non-supplemented diets. There was a significant Fe × phytase interaction effect. Tibia Fe content was higher in birds fed on phytase-free diets with high Fe but the reverse was the case when phytase was added and their interaction was significant. High dietary Fe significantly increased the accumulation of Fe in liver.

5. Phytase improved Ca-Mg-ATPase, Ca-ATPase and Mg-ATPase activities in jejunum when supplemented to the diet containing 80 mg Fe/kg.

6. This study indicates that high (100 mg/kg) dietary Fe inhibited phytase efficacy and subsequently reduced the overall performance and nutrient utilisation of broilers.     

Growth and the plasma concentrations of growth hormone and prolactin in chicks: Effects of “environmental enrichment”, sex and strain

1. The effects of including novel objects in the environment ("environmental enrichment “) on body‐weight gain, relative body‐weight gain, gain : food ratio, plasma growth hormone (GH) and prolactin concentrations in male and female broiler and layer chicks was investigated.

2. Environmental enrichment improved body‐weight gain, relative body‐weight gain and gain: food ratio but had no effect on circulating GH or prolactin concentrations.

3. Weight gain and gain : food ratio were greater in the broilers than in the layer chicks, while plasma GH and prolactin (females only) concentrations were less.

4. There were no sex differences in weight gain and relative weight gain but gain : food ratio was significantly greater in females than in males. In both strains plasma GH concentrations were higher in males than in females and prolactin concentrations were higher in male than in female broilers.     

Effects of energy and protein allowances during lay on the reproductive performance of broiler breeder hens

1. Broiler parent stock were fed daily allowances of 1.88, 1.73 or 1.52 MJ apparent metabolisable energy (AME) per bird at two different daily protein intakes (27, 21.3 g crude protein (CP) per bird) or daily protein intakes of 24.6 and 19.4 g CP per bird at a daily energy intake of 1.88 MJ AME per bird from 21 to 64 weeks of age.

2. Body‐weight gain and carcass fat and water content increased and fertility decreased with increasing energy allowance. Maximum egg production occurred at an energy intake of 1.73 MJ AME/bird d.

3. Differences in egg weight and hatchability were related to differences in both energy and protein intake. The highest egg weight occurred at the highest allowance of energy and protein. Hatchability was depressed where the daily allowances of protein and energy were in a ratio of more than 15 g protein: 1 MJ AME.

4. Apart from egg size no significant effects on reproductive performance were observed when dietary protein intake was varied from 27 to 19.5 g/bird d.

5. Requirements of broiler breeder hens for protein during lay may be lower than previously thought. For the strain used a protein intake of 19.5 g/bird d appeared adequate provided essential amino acid concentrations were maintained.

6. The close relationships between body weight and energy allowance and the latter and egg production make body‐weight gain a useful guide to management. A body‐weight gain of about 1.1 kg from 21 to 36 weeks of age was associated with optimum performance in this study.     

Effects of dietary medium-chain fatty acids on performance,carcass characteristics,and some serum parameters of broiler chickens

1. This study aimed to evaluate the effects of dietary medium-chain fatty acids (MCFAs) on the performance, carcass characteristics, and some serum parameters of broiler chickens.

2. A total of 176 one-day-old male broiler chicks (Ross 308) were assigned to four treatments including control treatment (basal diet), 0.1% MCFA, 0.2% MCFA, and 0.3% MCFA treatments according to a completely randomised design. Each treatment consisted of 4 replicates with 11 chicks for each replicate. In MCFA treatments, the amounts of MCFAs were added to basal diet as a substitution of soybean oil.

3. There were not any significant differences in body weight, feed intake, and feed conversion ratio among the treatments in different stages of the experiment. However, MCFA treatments had a lower abdominal fat and a higher breast yield compared to control treatment.

4. Blood glucose, cholesterol, and low-density lipoprotein (LDL)-cholesterol concentrations were significantly decreased, but blood high-density lipoprotein (HDL)-cholesterol concentration was significantly increased in the MCFA treatments compared to the control treatment.

5. These results indicate that dietary MCFA has a positive effect on the health and productivity of broiler chickens.     

Effects of high inclusion rates of salseed meal in the diet of chicks

1. Starter diets containing either maize or salseed meal to replace the maize were fed to chicks over a period of 2 weeks.

2. Growth rate, food intake, food utilisation and proportion of dietary nitrogen retained were much poorer in chicks receiving salseed meal.

3. The chicks receiving salseed meal developed pathological lesions in liver and kidney.

4. The red blood cell count, white blood cell count, haemoglobin concentration and packed cell volume of the chicks receiving salseed meal were lower than those of chicks receiving maize.

5. The apparent metabolisable energy value of salseed meal was determined as 6.83 MJ/kg.     

The response of egg weight to the inclusion of different amounts of vegetable oil and linoleic acid in the diet of laying hens

1. Four diets containing different amounts of vegetable oil and linoleic acid were fed to White Leghorn hens throughout a full laying year.

2. Egg weight was poor with the low fat basal diet but increased in relation to the amounts of maize oil (4 and 30 g/kg) included in the diet.

3. With a diet containing 30 g olive oil/kg, egg weight was similar to that obtained with the diet containing the same amount of maize oil.

4. Rearing the birds on diets containing low or moderate amounts of linoleic acid did not affect the response to fatty acid content of the layer's diet.

5. It is concluded that the requirement of the laying hen for linoleic add is not higher than 9 g/kg but that egg weight does respond to higher dietary amounts of readily absorbable fatty acids.     

Response of broiler chickens to well‐balanced protein mixtures

1. Four experiments were conducted on broiler chickens between one and three weeks of age to determine their response to dietary protein concentrations.

2. Diets prepared by serial dilution of a concentrated protein mixture, well‐balanced with respect to all essential amino acids, were fed in three experiments, while in a fourth experiment, a lysine‐deficient protein mixture was used.

3. Response curves relating body‐weight gain to increasing concentrations of protein and of lysine intake are presented.

4. A table is presented from which optimum protein intakes can be calculated according to changes in input and output costs and changes in growth potential of the chickens.     

Effects of dietary boron and phytase supplementation on growth performance and mineral profile of broiler chickens fed on diets adequate or deficient in calcium and phosphorus

1. Two experiments were designed to determine the effect of dietary boron (B) in broiler chickens. In Experiment 1, a 2 × 4 factorial arrangement of treatments was used to investigate the effect of dietary calcium (Ca) and available phosphorus (aP) (adequate or deficient) and supplemental B (0, 20, 40, and 60 mg/kg diet). In Experiment 2, B, at 20 mg/kg, and phytase (PHY) (500 FTU/kg diet) were incorporated into a basal diet deficient in Ca and aP, either alone or in combination.

2. The parameters that were measured were growth performance indices, serum biochemical activity as well as ash and mineral (i.e. Ca, P, Mg, Fe, Cu and Zn) content of tibia, breast muscle and liver.

3. Results indicated that both supplemental B and dietary Ca and aP had marginal effects on performance indices of chickens grown for 42 d.

4. There were positive correlations (linear effect) between B concentrations of serum, bone, breast muscle and liver and the amount of B consumed.

5. Serum T₃ and T₄ activities increased linearly with higher B supplementation.

6. Increasing supplemental B had significant implications on breast muscle and liver mineral composition. Lowering dietary Ca and aP level increased Cu content in liver and both Fe and Zn retention in breast muscle. Tibia ash content and mineral composition did not respond to dietary modifications with either Ca–aP or B.

7. The results also suggested that dietary contents of Ca and aP do not affect the response to B regarding tissue mineral profile. Dietary combination with B and PHY did not create a synergism with regard to growth performance and bioavailability of the minerals.     

Dietary glycine+serine responses of male broilers given low-protein diets with different concentrations of threonine

1. The objective of this study was to determine the optimum glycine+serine (Gly+Ser) concentration in low-crude protein (CP) diets that have adequate or high concentrations of dietary threonine (Thr) for broiler chickens in the initial growth phase.

2. Treatments consisted of four concentrations of dietary Gly+Ser (18.4; 19.8; 21.2 and 22.6 g/kg) and two concentrations of dietary Thr (9.3 and 10.7 g/kg, corresponding to 100 and 115% of the required Thr, respectively).

3. At 21d, interactions were observed between dietary Gly+Ser and Thr concentrations for the feed conversion ratio, creatine content in the pectoral muscles and serum concentrations of uric acid. There was a quadratic effect of the concentrations of Gly+Ser in the diets with 9.3 g Thr/kg on the feed conversion ratio and creatine content in the pectoral muscles, with an optimisation concentration of 20.8 and 21.1 g Gly+Ser/kg, respectively.

4. Diets containing 10.7 g Thr/kg negatively affected the feed conversion ratio, relative breast weight, creatine content in the pectoral muscles, serum concentrations of uric acid and ammonia in poultry compared to diets containing 9.3 g Thr/kg.

5. The need for Gly+Ser in diets with low-protein concentration (190 g CP/kg) and adequate concentration of Thr (9.3 g/kg) is 20.8 g/kg for broilers in the 1- to 21-d phase.     

Comparisons of egg quality traits,egg weight loss and hatchability between striped and normal duck eggs

1. The egg quality of striped and normal duck eggs was compared to determine why striped eggs show decreased hatchability. A total of 430 eggs, obtained from a Pekin duck breeder flock aged 50–65 wks, were used in three experiments. The eggs were weighed and assigned randomly to measure egg quality traits, egg weight (EW) loss and hatchability during incubation.

2. There were no significant differences between egg types in terms of egg shape index, eggshell strength and thickness, albumen height, Haugh unit, yolk colour, weight of the eggshell with or without membranes, calcium, phosphorus, copper and manganese contents in the eggshell (with the inner and outer membranes or without the inner membrane), albumen weight, dry matter of albumen, crude protein (CP) of thick albumen and pH of the thick albumen.

3. The weight of eggshells with membranes, weight of thick albumen and CP of thin albumen in striped eggs were lower than those in normal eggs.

4. The thin albumen in striped eggs was heavier than that in normal eggs. The pH of the thin albumin in striped egg was significantly higher than that in normal eggs.

5. There were no significant differences in EW loss during incubation or duckling weight between striped and normal eggs. However, the hatchability of striped eggs was lower.

6. The lower weight of the eggshell inner membrane and thick albumen, lower CP content and higher pH in the thin albumen of striped eggs might contribute to lower hatchability.     

Effects of dietary supplementation with Gynura procumbens (Merr.) on egg yolk cholesterol,excreta microflora and laying hen performance

1. The present study investigated the effects of dietary supplementation with Gynura procumbens on egg yolk and serum cholesterol and triglycerides, excreta microflora, laying performance and egg quality.

2. A total of 160 Hy-Line Brown layers (45 weeks old) were randomly assigned into 4 treatments on the basis of laying performance. Each treatment had 4 replicates with 10 birds each.

3. Dietary treatments were basal diet supplemented with 0 (control), 2.5, 5.0 and 7.5 g/kg diet G. procumbens during 56-d feeding period.

4. Serum (d 21, 42 and 56) and egg yolk (d 28, 42 and 56) cholesterol and triglycerides concentrations were linearly reduced with increasing dietary concentrations of G. procumbens.

5. Increasing dietary concentrations of G. procumbens linearly reduced the excreta total anaerobic bacteria (d 28), Clostridium sp. and Escherichia coli (d 28 and 56) populations.

6. Overall egg production and egg mass were linearly increased, and overall feed efficiency was linearly improved with increase in dietary G. procumbens.

7. Dietary increasing concentrations of G. procumbens linearly improved egg yolk colour (d 28 and 56) and breaking strength of eggs (d 56).

8. The results obtained in the present experiment indicate that dietary supplementation with G. procumbens could reduce the egg yolk cholesterol, suppresses harmful excreta microflora and improves layers performance.     

Effect of increasing cellulose in diets fed as crumbles or mash on the food intake and weight gains of broiler and Leghorn chicks

1. Two‐week‐old broiler and Leghorn cockerels were fed on diets containing 0, 100, 200, 300, 400, 500 or 600 g cellulose/kg in either crumble or mash form for 4 weeks.

2. Intake of the mash form of the cellulose‐diluted diets and associated body weights were less than those associated with the equivalent crumble diets which may have been due to decreased palatability of the former.

3. Broilers were unable to compensate for dietary dilution with cellulose by increasing food intake sufficiently to maintain nutrient intake with either mash or crumbled diets at any dilution.

4. At 100 g cellulose/kg for the mash diets and 100 and 200 g/kg for crumbled diets, Leghorns increased volume ingested by as much as 40% and maintained body‐weight gain and nutrient intake.

5. The results could be of value in designing feeding programmes for egg‐and meat‐type pullets.