V. Pirgozliev

Chemical composition and the nutritive quality of different wheat cultivars for broiler chickens

1. Different wheat cultivar samples were grown in replicated trials on a single site in three harvest years. A total of 23 wheat samples were harvested. Nutritionally complete, meal-form diets that included each wheat sample at 650 g/kg were used to compare broiler growth performance and determine apparent metabolisable energy (AME). The relationships were examined between these variables of nutritive value for broilers and the chemical composition and tests of quality on the wheat samples. 2. The total starch contents of the wheat samples ranged from 594 to 732 g/kg dry matter (DM). The mean total non-starch polysaccharide (NSP) content was 100 g/kg DM comprising 73·5 g/kg DM of insoluble material. Endosperm hardness ranged between 10 and 77 relative units and Beaver was the softest cultivar in two of the batches of samples. The AME of the wheat-based diets had a maximum range of 0·5 MJ/kg within each of the three batches of wheat that were tested. 3. Endosperm hardness of the wheat grains, within a harvest year, was positively correlated with broiler weight gain and the 1000-grain weight was negatively correlated with feed conversion efficiency (FCE). Starch content and gross energy were positively correlated with determined AME, and DM, 1000-grain weight and water holding capacity were negatively correlated with AME. 4. A step-wise regression technique indicated that endosperm hardness and ash content of the wheat were the explanatory variables that, within harvest years, significantly reduced the unexplained variation in broiler growth rate, feed intake and FCE. The contents of total starch, crude protein and ether extract were the explanatory variables that, within harvest years, significantly reduced the unexplained variation in AME.

Effect of excess dietary sodium, potassium, calcium and phosphorus on excreta moisture of laying hens.

1. Four experiments were conducted to investigate the effects of dietary concentrations of sodium, potassium, calcium or phosphate on the water intake and excreta moisture of laying hens. A fifth experiment examined the effect on these variables of increasing amounts of 2 different sodium salts (chloride or bicarbonate) and the interactions with 2 levels of dietary phosphorus. 2. All experiments involved individually caged laying hens fed on diets varying in 1 or 2 minerals in replacement for washed sand. The experimental diets contained mineral concentrations that either met or exceeded the expected requirement of the hens. The diets were given for a 7 or 8 d feeding period and food and water intakes were measured and excreta were collected for the last 48 h of each feeding period. These data were corrected for evaporative water loss to the environment during the collection period. 3. Increasing dietary concentrations of sodium, potassium or phosphorus gave linear increases ( P <0.001) in the water intake of the laying hens and linear increases ( P <0.01) in the moisture content of their excreta. Each 1 g/kg increase in dietary mineral increased the moisture content of the excreta by 9.04 ( ± 1.57), 11.95 ( ± 2.02) and 5.59 ( ± 0.31) g/kg ( ± standard error) for sodium, potassium and phosphorus, respectively. Increasing concentrations of dietary calcium did not significantly affect the water intakes or excreta moisture levels of the laying hens. 4. The fifth experiment showed that, although there was a sodium × phosphorus interaction ( P <0.05), the effects of the 2 mineral additions were approximately additive. There were no significant differences ( P >0.05) in water intakes or excreta moisture contents due to the 2 different sodium salts (chloride or bicarbonate).

Effects of dietary phytase on performance and nutrient metabolism in chickens

1. A broiler growth study was conducted to compare the effect of different concentrations of an Escherichia coli-derived phytase on performance, apparent metabolisable energy (AME), nitrogen (N), amino acid and mineral metabolisability, sialic acid excretion and villus morphology when fed to broiler chickens. 2. Female Ross 308 broilers (480) were reared in floor pens from 0 to 28 d of age. All birds were fed on nutritionally complete starter (0 to 21 d of age) and grower diets (21 to 28 d of age) with the exception that they were low in P (28 and 23 g/kg available P, respectively). These maize–soy diets were supplemented with 0, 250, 500 or 2500 phytase units (FTU)/kg feed. 3. Between 21 and 28 d of age, two birds from each floor pen were selected, and each pair placed in one of 32 metabolism cages (two birds per cage). Feed intake was recorded and excreta collected for the last 2 d of the feeding period, and AME, N, amino acid and mineral metabolisability coefficients and endogenous losses were determined following a total collection procedure. 4. Feed intake and weight gain increased in a linear manner in response to phytase dose, with an average increase of approximately 11·7 and 13·5%, respectively, compared with chickens fed on the low-P diet. Birds given diets with 2500 FTU weighed 6·6% more and had a 2·4% higher feed conversion efficiency (FCE) than those fed on diets containing 500 FTU. 5. Enzyme supplementation increased the intake of AME and metabolisable N by 10·3 and 3·9%, respectively, principally through increases in feed intake. Birds given enzyme-supplemented diets also improved their intake of metabolisable amino acids and P by approximately 14 and 12·4%, respectively, compared with birds fed on the control diet. Enzyme supplementation did not affect ileal villus morphometry of the birds. †Dr O. Oduguwa is visiting scientist from University of Agriculture, PMB 2240, Abeokuta, Nigeria.

The effect of changing the excreta moisture of caged laying hens on the excreta and microbial contamination of their egg shells

1. An experiment that included 1440 caged laying hens in 24 experimental units was conducted to determine the effect of differences in excreta moisture on the proportion of dirty eggs and the microbial contamination of eggs that were ostensibly uncontaminated by excreta. Excreta moisture contents were changed by giving the hens diets that contained 4 different concentrations of sodium. 2. Diets containing 1.6, 5, 10 or 15 g/kg dietary sodium were fed ad libitum to 1140 laying hens for a 12-week feeding period. A sample of excreta was collected from each experimental unit each week and its moisture content determined. All eggs produced were classified as clean or dirty according to the European Community Egg Marketing Regulations. A sample of eggs were collected from each experimental unit on 4 separate occasions in the last 4 weeks of the feeding period and the total bacterial numbers on ostensibly clean egg shells were determined. 3. Increasing dietary sodium concentration gave linear (P <0.01) increases in excreta moisture. Each 100 g/kg increase in excreta moisture increased (P <0.001) dirty egg numbers by 0.52% of the total eggs produced. Increasing excreta moisture gave a linear increase (P <0.001) in the (log-transformed) numbers of microorganisms that contaminated ostensibly clean egg shells.

A mixture of carvacrol, cinnamaldehyde, and capsicum oleoresin improves energy utilization and growth performance of broiler chickens fed maize-based diet

A total of 210, 1-d-old Ross 308 male broiler chickens were used in an experiment to investigate the effects of a supplementary mixture containing 5% carvacrol, 3% cinnamaldehyde, and 2% capsicum on dietary energy utilization and growth performance. The 2 diets were offered ad libitum to the chickens from 0 to 21 d of age. These included a maize-based control diet and the control diet with 100 g/t of supplementary plant extracts. Dietary apparent ME, N retention (NR), and fat digestibility (FD) coefficients were determined in the follow-up metabolism study between 21 and 24 d of age. Feeding the mixture of carvacrol, cinnamaldehyde, and capsicum increased weight gain by 14.5% (P = 0.009), improved feed efficiency by 9.8% (P = 0.055), and tended to increase (P = 0.062) carcass energy retention and reduce (P = 0.062) total heat loss compared with feeding the control diet. There was a 16.1% increase (P = 0.015) in carcass protein retention but no difference in carcass fat retention. Feeding plant extracts improved dietary FD by 2.1% (P = 0.013) but did not influence dietary NR. Supplementation of plant extract resulted in a 12.5% increase (P = 0.021) in dietary NE for production (NEp), while no changes in dietary ME were observed. The experiment showed that although dietary essential oils did not affect dietary ME, they caused an improvement in the utilization of energy for growth. Plant extracts may affect metabolic utilization of absorbed nutrients. Studies that have focused solely on the effect of plant extracts on ME alone may well have not detected their full nutritional value.

Effects of different dietary phytase activities on the concentration of antioxidants in the liver of growing broilers

One-hundred and fifty male chickens were used to evaluate the effects of different activities (0, 250, 500, 12 500 FTU/kg) of phytase on their performance and antioxidant concentration in the liver. The chicks were housed in 30 cages and were allocated to six replicates of five dietary treatments. All diets were formulated to be adequate in energy and protein (12.90 MJ/kg metabolizable energy, 214 g/kg crude protein), however, the negative control (NC) was lower in available P compared with the positive control (PC) (2.5 vs. 4.5 g/kg diet). The other three diets were the NC supplemented with phytase at 250, 500 and 12 500 FTU/kg (NC + 250, NC + 500 and NC + 12 500 FTU respectively). The concentration of antioxidants in the liver of the birds was determined using HPLC at 21 days of age. Low P diets (NC) reduced weight gain, however, supplementation with phytase improved weight gain to the extent that it was better than the PC at the 12 500 FTU treatment (p < 0.05). Feed conversion ratio was also improved by the high level of phytase supplement more than other treatments (p < 0.05). Feed consumption was not affected either by dietary phosphorus concentration or by different phytase supplementation. The antioxidant data showed that the unsupplemented diet with low phosphorus (NC) decreased the concentration of coenzyme Q(10) and retinol-linoleate in the liver compared with that of birds on the adequate phosphorus treatment (PC). Phytase supplementation, especially at the higher doses (500 and 12 500 FTU) increased the level of coenzyme Q(10) to the same level as the PC treatment. In addition, the highest dose (12 500 FTU) of phytase increased retinol concentration in the liver of chickens compared with those on the NC treatment. The highest inclusion level of phytase increased the alpha-tocopherol level in the liver compared with the lower levels of phytase (NC + 250 and NC + 500 FTU).

Energy metabolisability and digestibility of amino acids by broilers fed on malted sorghum sprouts supplemented with polyethylene glycol, charcoal, phytase and xylanase

1. A precision feeding study was conducted to determine the metabolisable energy and amino acid digestibility in broilers fed on malted sorghum sprouts (MSP) supplemented with polyethylene glycol (PEG), charcoal (CH), phytase and xylanase. 2. A total of 64 male Ross broilers housed individually (8 replicates per treatment) were fed 30 g of the feedstuff as follows by gavage: MSP, MSP + 1 g PEG/kg, MSP + 10 g PEG/kg, MSP + 1 g CH/kg, MSP + 10 g CH/kg, MSP + 3600 IU of evolved E. coli phytase/kg (EC 3.1.3.26) and MSP + 1600 IU of bacterial xylanase/kg (EC 3.2.1.8). Another group of birds was used for the assessment of endogenous loss and they were provided with 50 ml glucose solution each by gavage. 3. True dry matter digestibility (TDMD), true nitrogen retention (TNR), total tract digestibility of apparent and true metabolisable energy (AME and TME) and amino acid (AAD and TAAD) were determined. 4. MSP contained 244·4, 24·0, 74·9 and 224·0 g/kg of crude protein, ether extract, ash and neutral detergent fibre, respectively. The total tannin content of the product was 140 g/kg and 99% of this was bound. 5. The various dietary treatments did not significantly affect the TDMD, TNR, AME and TME of MSP. The low values (0·471 g/g, −0·164 g/g, 6·15 MJ/kg and 9·31 MJ/kg, respectively) for the above measurements depicted the low feeding value of un-supplemented MSP for poultry. Also, PEG, CH and enzymes did not improve the AAD and TAAD of MSP for poultry. 6. It was concluded that the tannin content of MSP is high and it appeared to be bound with other nutrients thereby reducing their availability. This may explain its low AME and amino acid digestibility and the lack of effect of the various treatments for poultry.

Dietary essential oils improve the hepatic antioxidative status of broiler chickens

Abstract 1. A total of 200 male Ross 308 chickens were used to evaluate the effects of a standardised combination of essential oils including 5% carvacrol, 3% cinnamaldehyde and 2% capsicum oleoresin (XT 6930; Pancosma S.A., Geneva, Switzerland) on their performance, hepatic antioxidant concentration and caecal tonsils morphometry. 2. Two diets were offered to broiler chickens from d old to 21 d of age. The control diet (C) was slightly lower in metabolisable energy (12.13 MJ/kg ME) and crude protein (215 g/kg CP) than breeders’ recommendation. The second diet, made as XT 6930, was added on the top of the control diet at 100 mg/kg. Each diet was offered ad libitum to birds housed in one of 10 floor pens in a randomised complete block design. The birds were housed in 20 floor pens, 10 birds in each pen, and were allocated to 10 replicates of the two dietary treatments. 3. The concentration of antioxidants in the liver of the birds was determined using high-performance liquid chromatography (HPLC) at 21 d of age. Birds fed control diet only had lower weight and converted less efficiently feed to gain compared to birds fed essential oils-supplemented diet. Feed consumption was not affected by dietary treatments. The antioxidant data showed that supplemented essential oils improved the hepatic concentration of carotenoids and coenzyme Q10 when fed to broiler chickens. The morphometry of the caecal tonsils of the birds was not influenced by dietary treatments. 4. It can be concluded that that dietary combination of essential oils, including carvacrol, cinnamaldehyde and capsicum oleoresin, improved growth, feed efficiency and the hepatic concentration of carotenoids and coenzyme Q10 when fed to broiler chickens.

Previous exposure to dietary phytase reduces the endogenous energy losses from precision-fed chickens

1. A precision feeding experiment was conducted with broiler chickens, which were previously fed on diets with or without phytase, to study the effects of previous exposure to dietary phytase supplementation on the excretions of endogenous energy, nitrogen, amino acids and minerals. 2. Female Ross 308 broiler chickens, which had previously received one of 4 experimental diets (low P maize/soy diets (control, D), D + 250 international units of phytase per kg diet (FTU), D + 500 FTU and D + 2500 FTU) were used in the study. All birds were starved and then given 50 ml of glucose solution at 44 d of age. The birds were allocated to individual metabolism cages in a randomised block design with 8 replicates of each of the 4 dietary treatments. 3. Chickens which had been previously fed on diets supplemented with phytase excreted 32% less energy and 28% less dry matter per kg metabolic body weight (W0⋅75) from endogenous sources, compared to birds fed the unsupplemented diet. 4. Birds previously given phytase supplemented diets excreted 60% less sodium than those given the control diet, but there was no effect on all other minerals investigated. There was no effect of diet on the excretion of endogenous N, sialic acid or amino acids. 5. The results showed that the effects of feeding chickens on diets with supplementary phytase may continue for a few days after the diets are withdrawn. This suggests that previous exposure to phytase may alter the nutritive value of follow-on diets, which may be a commercially important effect.

Energy utilisation and growth performance of chicken fed diets containing graded levels of supplementary bacterial phytase.

A total of 364 female Ross 308 chicks (1 d old) were used in the present study conducted in floor pens to investigate the effects of graded levels of supplementary bacterial phytase on dietary energy utilisation and growth performance. For this purpose, four maize-soyabean-based diets were offered to the birds from 0 to 21 d of age. These included a suboptimal P negative control (NC, 3.0 g/kg non-phytate P), NC+250 phytase units (FTU)/kg feed, NC+500 FTU and NC+2500 FTU. The effect of phytase activity on bird growth performance was best described as a linear relationship between increasing dose and increased feed intake (P< 0.001), but was quadratic for body-weight gain (P= 0.002) and feed efficiency (P= 0.023). There was no significant response (P>0.05) of dietary apparent metabolisable energy (AME) to supplementary phytase. The birds fed phytase increased their retention of total carcass energy in a linear fashion (P= 0.009) with increased phytase dose. The efficiency of dietary AME used for overall carcass energy retention also improved (P= 0.007) in a linear manner with increased dietary phytase activity. Dietary net energy for production (NEp) increased (P= 0.047) with an increase in phytase dose following a linear pattern, as an increase of 100 FTU increased dietary net energy by 15.4 J (estimated within the range of doses used in the present experiment). Dietary NEp was more highly correlated with performance criteria than dietary AME, and it seems to be a more sensitive way to evaluate broiler response to phytase supplementation.