South Africa currently produces 70% of the world’s ostrich products. The profit margin of South African producers from the sale of ostrich meat, leather and feathers currently stands at 20%, 65% and 15%, respectively.

Local producers want to increase the production of ostrich products but keep production costs as low as possible. Maintaining optimal nutrition of breeding stock is necessary to increase the production of ostrich chicks, thereby decreasing the fixed costs per chick.

This research examined the impact on ostrich reproduction of replacing soya oilcake (SOC) as a protein supplement with cheaper cottonseed oilcake (CSOC). Although there are no data available on the impact of CSOC feed on ostrich reproduction, it is well known that gossypol, a naturally occurring toxin in cotton plants, negatively affects male reproduction in other monogastric species and that it may also reduce appetite.

Ninety-six breeding ostrich pairs were divided into two groups to compare the effects of diet (CSOC and SOC) during the breeding season on ostrich-breeding parameters. The replacement of SOC with CSOC had no significant effect on the number of total eggs produced (47.8 ± 5.3 versus 48.3 ± 5.1 per breeding pair, respectively) or infertile eggs (31.5 ± 3.9 versus 38.0 ± 5.2, respectively). Also, the number of dead-in-shell chicks did not differ significantly between groups (20.2 ± 3.3 versus 26.8 ± 3.8, respectively).

Even though none of these breeding parameters differed, the replacement of SOC with CSOC in the diets of breeding birds led to significantly more chicks hatching per hen from breeding birds fed on the SOC (36.1 ± 4.8) than the CSOC diet (17.2 ± 3.8).

Although it would thus seem that feeding breeding ostriches CSOC instead of SOC as a protein supplement will have a detrimental effect on chick production, more data are required to deliver a definitive answer.

A study was conducted with breeding ostriches over two consecutive breeding seasons to determine their response to different concentrations of a well-balanced dietary protein.

Five concentrations of protein were fed to both females and males at an intake of 2.5 kg/bird d. The respective diets contained 75, 91, 108, 123 and 140 g protein/kg feed with energy held constant at 9.2 MJ metabolisable energy/kg feed.

Egg production (mean ± SE, 39.1 ± 3.6 eggs/female/season) was unaffected by dietary protein concentration. Similarly, no significant trends were found for the number of unfertilised eggs (9.1 ± 1.8), dead-in-shell chicks (8.2 ± 1.3), the number of chicks hatched (19.5 ± 2.5) and change in the mass of females (?16.3 ± 10.2 kg). Egg weight decreased linearly as dietary protein content increased.

Age of the ostrich female had a highly significant effect on the number of eggs laid, the number of chicks hatched, the number of dead-in-shell and infertile eggs produced per hen, as well as the mass change of female breeding birds, but did not affect the response of any of these variables to dietary protein content.

It was concluded that ostriches do not benefit from dietary protein contents greater than about 75 g/kg when this is fed at a daily total feed intake rate of 2.5 kg/bird during the breeding season.

An experiment was conducted to determine the effects of dietary supplementation of thymol, synbiotic (Biomin, IMBO) and their combination in laying hen diets on laying performance, egg quality and serum metabolic profile from 24 to 36 weeks of age.

Treatment groups were fed on a control diet, the control diet supplemented with thymol (250 mg/kg), the control diet supplemented with synbiotic (250 mg/kg) or the control diet supplemented with a combination of thymol (250 mg/kg) and synbiotic (250 mg/kg).

Supplementation of thymol and synbiotic, separately as well as combined, improved egg weight, egg production, egg mass and feed conversion ratio from 24 to 36 weeks of age. The eggs obtained from thymol, synbiotic or their combination treatments displayed higher values of shell thickness, Haugh unit and shell percentage compared to the control.

Serum cholesterol significantly decreased in the single or combined form of thymol and synbiotic supplementation treatments.

The pharmacokinetics of enrofloxacin and marbofloxacin was studied in Japanese quails and common pheasants. Healthy mature birds from both species and both genders were treated intravenously and orally with enrofloxacin (10 mg/kg) and marbofloxacin (5 mg/kg).

After intravenous administration enrofloxacin was extensively metabolised to ciprofloxacin. Metabolites of marbofloxacin were not detected. Values of volume of distribution were respectively 4.63 l/kg and 3.67 l/kg for enrofloxacin and 1.56 l/kg and 1.43 l/kg for marbofloxacin. In quails, total body clearance values were higher than those in pheasants and other avian species.

After oral application enrofloxacin was rapidly absorbed in quails, more rapidly than marbofloxacin. Pheasants absorbed both antimicrobials at a lower rate. Higher bioavailability was observed for marbofloxacin (118%). Relatively low bioavailability was established in quails for enrofloxacin (26.4%), accompanied by extensive conversion to ciprofloxacin.

Generally, quails absorbed and eliminated both fluoroquinolones more rapidly than pheasants; the latter showed pharmacokinetics similar to poultry. Because of favourable pharmacokinetic properties, marbofloxacin should be preferred for oral administration in Japanese quails and pheasants for treatment of infections caused by equally susceptible pathogens.

The aim of the study was to determine the effects of dietary supplementation with sodium nitroprusside (SNP), a nitric oxide (NO) exogenous donor, and N^G-nitro-l-arginine methyl ester (l-NAME), a NO inhibitor, on growth performance, some biochemical parameters and ovarian primordial and primary follicles of quail.

A total of 480 Japanese quail (Coturnix coturnix japonica), one-day-old, including both males and females, were randomly allocated into one control group and 4 treatment groups each consisting of 96 birds. The control group was fed on the basal diet, whereas the experimental groups were fed on the basal diet supplemented with 50 mg SNP/kg, 200 mg SNP/kg, 50 mg l-NAME/kg or 200 mg l-NAME/kg.

In the group receiving 200 mg SNP/kg, BW was lower on d 28 and d 42 compared to the control group and body weight gain (BWG) was lower between weeks 2 and 4 compared to the control group. In the same group, BWG and feed consumption were lower compared with the control group. In the group receiving 200 mg l-NAME/kg, BW on d 42 and BWG were lower, whereas feed consumption and FCR was higher than in the control group.

In the groups supplemented with SNP at 50 and 200 mg/kg, serum total protein and albumin were higher than the control group; however, serum lipid profile, and liver and kidney enzymes were not affected by supplementation with SNP or l-NAME.

The numbers of ovarian primordial and primary follicles were greater in the group fed on the diet supplemented with 200 mg SNP/kg compared with the control group. Supplementation at 200 mg l-NAME/kg diet reduced the number of primary follicles compared to the controls, whereas the diameter of primordial and primary follicles increased.

In conclusion, supplementation with SNP and l-NAME depressed quail growth. Furthermore, the increase in NO following dietary supplementation with the NO-donor SNP delayed the growth process from primordial to primary and primary to secondary follicle transition in quail.

The aim of this study was to investigate the individual and combined effects of rosemary, oregano and fennel volatile oil (FVO) supplementation on the performance and ilio-caecal bacteriological flora of broiler chickens.

A total of 800 male Ross-308 broiler chickens were divided equally into 8 groups; each contained 100 chickens. The study included a control treatment (NC) with no dietary additives that was supplemented with oils according to the following 7 treatments: 200 mg α-tocopherol acetate/kg (PC), 100 mg oregano volatile oil (OVO)/kg, 100 mg rosemary volatile oil (RVO)/kg, 100 mg FVO/kg and an equal mixture of oregano+rosemary+fennel VO (100, 200, 400 mg/kg, VOM-1, VOM-2 and VOM-3, respectively). The experiment lasted for 6 weeks.

At the end of the experiment, dietary supplementation with α-tocopherol, oregano, rosemary and FVO and two different volatile oil mixtures (VOMs) (VOM-2; VOM-3) significantly increased the body weights (BWs) of broilers at 7, 14 and 21 d of age compared to the negative control (NC) (?) and VOM-1 groups. At 0–42 d, birds fed on VOM-3 were considerably heavier and also gained more weight than NC (?) and VOM-1 groups.

The blend of VOs at 400 mg/kg significantly increased Lactobacillus spp. in faeces. The blends of oregano, rosemary and FVOs (VOM-3) at 400 mg/kg concentration and also VOM-3 group exhibited stronger antibacterial activity against coliform bacteria compared to the NC (?) group.

In conclusion, the blend of oregano, rosemary and fennel VOs at higher concentrations (400 mg/kg concentration) in diets can be used to stimulate the growth and can improve the intestinal microbial balance (including a reduction of coliform bacteria and an increase in Lactobacillus spp. counts) of broiler chickens.

The purpose of this study was to determine the effect of limestone particle size and calcium (Ca) to non-phytate phosphorus (P) ratio on the true ileal Ca digestibility of limestone for broiler chickens. A limestone sample was passed through a set of sieves and separated into fine (<0.5 mm) and coarse (1–2 mm) particles. The analysed Ca concentration of both particle sizes was similar (420 g/kg).

Six experimental diets were developed using each particle size with Ca:non-phytate P ratios of 1.5:1, 2.0:1 and 2.5:1, with ratios being adjusted by manipulating the dietary Ca concentrations. A Ca-free diet was also developed to determine the basal ileal endogenous Ca losses. Titanium dioxide (3 g/kg) was incorporated in all diets as an indigestible marker.

Each experimental diet was randomly allotted to 6 replicate cages (8 birds per cage) and fed from d 21 to 24 post hatch. Apparent ileal digestibility of Ca was calculated using the indicator method and corrected for basal endogenous losses to determine the true Ca digestibility.

The basal ileal endogenous Ca losses were determined to be 127 mg/kg of dry matter intake.

Increasing Ca:non-phytate P ratios reduced the true Ca digestibility of limestone. The true Ca digestibility coefficients of limestone with Ca:non-phytate P ratios of 1.5, 2.0 and 2.5 were 0.65, 0.57 and 0.49, respectively.

Particle size of limestone had a marked effect on the Ca digestibility, with the digestibility being higher in coarse particles (0.71 vs. 0.43).

An experiment with a 2 × 3 factorial design with two concentrations of dietary betaine (0 and 600 mg/kg) and three dietary concentrations of methionine (0, 600 and 1200 mg/kg) was conducted using goslings to estimate growth, nutrient utilisation and digestibility of amino acids from 21 to 70 d of age.

Three hundred geese were randomised at 18 d of age into 6 groups with 5 replicates per treatment and 10 geese per replicate.

Increasing dietary concentrations of methionine gave a linear increase in body weight and average daily gain. The coefficient of crude fat retention increased as dietary methionine increased and there was a significant non-linear response to increasing dietary methionine. Similarly, increasing supplemental methionine gave linear increases in the digestibility of methionine and cysteine.

The results of this study indicated that optimal dietary supplementation of methionine could increase growth performance and methionine and cysteine utilisation in growing goslings. Betaine supplementation had no apparent sparing effect on methionine needs for growth performance, but did improve the apparent cysteine digestibility.

The effects of different dietary energy concentrations on ostrich production variables were examined in two separate trials. The first trial tracked changes in production variables from the pre-starter phase through the starter phase and grower phase. The second trial was based on the finisher phase per se. In both trials, the influence of dietary energy on feed intake, feed conversion ratio (FCR) and growth variables was investigated. Additionally, basic abattoir weights were recorded, and measurements of the feathers and skin were performed.

In both trials, three diets with different concentrations of dietary energy were given during each phase where the low-, medium- and high-energy concentrations for each phase were as follows: 13.5, 14.5 and 15.5 MJ ME/kg feed pre-starter; 12.5, 13.5 and 14.5 MJ ME/kg feed starter; 10.5, 11.5 and 12.5 MJ ME/kg feed grower and 9.5, 10.5 and 11.5 MJ ME/kg feed finisher. Feed and water were available ad libitum in both trials.

Overall, it was found that the best performance for growth, FCR, skin size and grade, live weight, carcass weight and thigh weight were obtained on the medium-energy diet during the pre-starter, starter and grower phases.

During the finisher phase, improved growth rate and tanned skin size was found in birds given the diet with the highest energy concentration (11.5 MJ ME/kg feed). Carcass weight, growth rate and certain feather variables were also significantly influenced by gender.

This study evaluated the effect of oral administration of colloidal gold nanoparticles on accumulation of gold in the small intestine and intestinal absorption of iron, calcium and potassium under in vitro conditions.

The gold nanoparticles are non-ionic, nanocrystalline, chemically pure particles 5 nm in size, produced in a physical process.

In total, 126 one day-old Ross 308 chicks were assigned to 7 experimental groups of 18 birds each (3 replications of 6 individuals each).

The control group (G-C) did not receive gold nanoparticles. Groups: Au-5(7), Au-10(7) and Au-15(7) received gold nanoparticles in their drinking water in the amounts of 5 mg l^?1 for group Au-5(7), 10 mg l^?1 for group Au-10(7) and 15 mg l^?1 for group Au-15(7) in 8–14, 22–28 and 36–42 d of life. The birds in groups Au-5(3), Au-10(3) and Au-15(3) received gold nanoparticles in the same amounts, but only in 8–10, 22–24 and 36–38 d of life.

The study revealed that nanogold supplied via ingestion leads to dose- and time-dependent accumulation of gold in the intestinal walls.

Nanogold present in the jejunum has a negative impact on the absorption of calcium, iron and potassium under in vitro conditions.

The objective of this study was to investigate the effect of a monocomponent protease and dietary inclusion of canola meal (CM) and poultry by-product meal (PBM) on growth performance, carcass characteristics and blood metabolites of turkeys fed on low crude protein (CP) diets from 28 to 55 d post hatch.

Experimental treatments included control, maize–soybean meal diet including 258.3 g/kg CP; negative control 1 (NC1), maize–soybean meal diet with reduced CP (232.4 g/kg); NC2, control diet (CP, 258.3 g/kg) including CM (80 g/kg) and PBM (80 g/kg); NC3, maize–soybean meal diet with reduced CP (232.4 g/kg) including CM (80 g/kg) and PBM (80 g/kg). Also, the NC1 + P and NC3 + P diets were created by addition of protease enzyme (30 000 units/kg of diet) to the NC1 and NC3 diets, respectively.

The NC3 group had lower body weight gain (BWG) compared to those fed on the control diet, and no improvement with enzyme addition (NC3 + P) was achieved. The protease addition to the NC1 diet (NC1 + P) improved BWG to the level of the control diet. The NC1 group had higher feed conversion ratio (FCR) compared to the control and NC3 + P, but protease addition to the NC1 diet improved FCR.

Protease addition to the low CP diets resulted in higher nitrogen (N) retention than in the control and NC2 groups. Also, the NC1 + P and NC3 + P diets increased apparent ileal digestibility (AID) of CP compared to the control group.

It was concluded that addition of CM (up to 80 g/kg) and PBM (up to 80 g/kg) to turkey diets had no negative effect on growth performance from 28 to 55 d of age. The NC1 + P group achieved the BWG of the control group which was partially due to increases in N retention and AID of CP, but the NC3 + P group failed to recover the growth losses. This difference implies that the efficacy of the protease may depend upon the protein source in the ration.

This study aimed to evaluate the influence of an organic acid (OA) and essential oil (EO) blends, individually or in combination, on growth performance, carcass parameters, apparent digestibility, intestinal microflora and intestinal morphology of broilers.

A total of 480 one-d-old male Ross 308 chicks were randomly assigned to 4 treatments consisting of 4 replicates each (n = 30 birds in each replicate). Dietary treatments consisted of a basal diet (control), and basal diet supplemented with 2 g/kg OA blend (OAB), 300 mg/kg EO blend (EOB), or with 2 g/kg OA and 300 mg/kg EO blend (OAB–EOB) for 42 d.

The dietary supplementation with EO blend or in combination with OA blend increased body weight gain and improved feed efficiency as compared to control. Dietary treatments had no significant effects on feed consumption or relative organ weights of broilers.

The OAB diet increased carcass yield compared to the control diet but the lowest carcass yield occurred with the OAB–EOB combination. Birds fed on EOB and OAB–EOB diets had lower ileum Escherichia coli counts than birds fed on the control diet.

There was no significant effect of treatments on apparent digestibility at 16–21 d but the EOB and OAB–EOB diets increased apparent digestibility of dry matter and crude protein during the finisher period (d 37–42) compared to the control diet.

Birds fed on the EOB and OAB–EOB diets had greater villus height in the ileum at 21 and 42 d of age and had lower crypt depth in the ileum at 42 d of age than birds given the control diet.

In conclusion, beneficial effects of the use of EO blend individually or in combination with the OA blend were observed but the OA blend alone was ineffective. Furthermore, the use of the combination of OA and EO was more effective, in some respects, than their individual use.

A trial was conducted to explore the effect of feeding graded concentrations of green tea extract (GTE; 125, 250, 500, 1000 and 2000 mg/kg) on the growth performance, serum lipid profile, liver glutathione-reduced, thigh muscle malondialdehyde and humoral immune response against Newcastle disease virus vaccines of broiler chickens from hatching to 42 d of age. The results of broilers fed on GTE were contrasted to those fed on butylated hydroxytoluene (BHT; 125 mg/kg) or unsupplemented controls.

The obtained results revealed no significant difference among treatments in the measured growth performance parameters (body weight, average daily gain, average daily feed intake and feed conversion ratio), per cent liveability and serum lipid profile (total lipid, total cholesterol, high-density, low-density and very low-density lipoprotein cholesterols).

Dietary intake of GTE resulted in a significant increase in the liver glutathione-reduced level compared to the control. The glutathione-reduced level of broilers fed on the BHT diet was not significantly different from that of broilers fed on GTE or control diets. Feeding GTE or BHT resulted in a significant decrease in the malondialdehyde level of meat tissue.

The specific antibody titre against Newcastle disease virus vaccines was significantly increased at 28 and 35 d of age in broilers fed on diets supplemented with GTE but not with BHT.

In conclusion, GTE was found to possess antioxidant and immunostimulant characteristics for broilers when supplemented to their diets, and its optimum inclusion level ranged from 125 to 500 mg/kg.

This study aims to analyse the influence of adding natural zeolites (clinoptilolite) to the diet or litter of broilers and their effects on growth performance, carcass yield and litter quality.

Three consecutive flocks of broilers were raised on the same sawdust litter, from d 1 to d 42 of age, and distributed in three treatments (control with no added zeolites, addition of 5 g/kg zeolite to diet and addition of 100 g/kg zeolites to litter).

The addition of zeolites to the diet or litter did not affect growth performance or carcass yield.

The addition of zeolites to the diet did not influence moisture content of the litter, ammonia volatilisation was reduced only in the first flock and pH of litter was reduced in the second and third flock.

However, the addition of zeolites to the litter reduced moisture content, litter pH and ammonia volatilisation in all flocks analysed.

The addition of 5 g/kg zeolite to the diet in three consecutive flocks was not effective in maintaining litter quality, whereas the addition of 100 g/kg natural zeolites to sawdust litter reduced litter moisture and ammonia volatilisation in three consecutive flocks raised on the same litter.

The diet of broiler chickens supplemented with increasing concentrations of copper (Cu) was assessed for the effect of Cu on liver mitochondrial function.

A total of 160, 1-d-old Cobb 500 broilers (Gallus domesticus) were randomly assigned in equal numbers into 4 groups, which differed in the concentration of copper supplements in the diet; 11 (control), 110, 220 and 330 mg of Cu/kg dry matter. Liver mitochondrial function was recorded at 12, 24, 36, 48 and 60 d of age.

Supplementation with 110 mg Cu/kg dry matter enhanced mitochondrial function and activities of complexes I–V, and this was significant at 36 d of age compared with the other diets (P < 0.05). Supplementation with 220 mg Cu/kg dry matter and 330 mg Cu/kg dry matter enhanced mitochondrial function and activities of complexes I–V at 12, 24 and 36 d of age, but displayed reduced function (P < 0.05) at 48 and 60 d of age except in complex IV (P > 0.05). Mitochondrial hydrogen peroxide (H₂O₂) production was also increased (P < 0.05) with an increase of copper supplementation in the diet.

The results indicate that appropriate dietary copper supplements are sufficient for improving mitochondrial function and activities of the respiratory complexes. Higher concentrations of copper, on the other hand, lead to copper toxicity by affecting certain respiratory complexes.

The present study was conducted to determine the effects of α-lipoic acid supplementation on post-mortem changes in the fatty acid profile and concentrations of nucleotide-related substances, especially those of a taste-active compound, inosine 5?-monophosphate, in chicken meat.

Mixed-sex broiler chicks aged 14 d were divided into three groups of 16 birds each and were fed on diets supplemented with α-lipoic acid at levels of 0, 100 or 200 mg/kg for 4 weeks. Blood and breast muscle samples were taken at 42 d of age under the fed condition and then after fasting for 18 h. The breast muscle obtained from fasted chickens was subsequently refrigerated at 2°C for one and 3 d.

α-Lipoic acid supplementation did not affect any plasma metabolite concentration independently of feeding condition, while a slight increase in plasma glucose concentration was shown with both administration levels of α-lipoic acid. In early post-mortem breast muscle under the fed condition, α-lipoic acid had no effect on concentrations of fatty acids or nucleotides of ATP, ADP, and AMP.

In post-mortem breast tissues obtained from fasted chickens, total fatty acid concentrations were markedly increased by α-lipoic acid feeding at 200 mg/kg irrespective of length of refrigeration. This effect was dependent on stearic acid, oleic acid, linoleic acid and linolenic acid. However, among fatty acids, the only predominantly increased unsaturated fatty acid was oleic acid.

Dietary supplementation with α-lipoic acid at 200 mg/kg increased the inosine 5?-monophosphate concentration in breast meat and, in contrast, reduced the subsequent catabolites, inosine and xanthine, regardless of the length of refrigeration.

Therefore, the present study suggests that α-lipoic acid administration altered the fatty acid profile and improved meat quality by increasing taste-active substances in the post-mortem meat obtained from fasted chickens.

The main dietary challenge in organic laying hen production is to fulfil the digestible methionine (MET) requirement in a diet consisting of ingredients of organic origin only.

The aim of the present experiment was to determine the response of organic housed laying hens (26–34 weeks of age) to dietary energy and MET during a summer and winter trial. Per trial, a total of 128 17-week-old Brown Nick hens were allotted to 16 pens, which were connected to an outdoor run. Each experiment comprised 8 dietary treatments according to a 4 × 2 factorial design. The factors were AFD MET level (2.3, 2.7, 3.1 and 3.5 g/kg) and energy content (10.9 and 12.1 MJ).

Dietary energy content did not affect energy intake (1361 kJ/d) in summer, whereas energy intake in winter was increased in hens that were fed on the 12.1-MJ diets (1514 vs. 1421 kJ/d). Maximal egg mass in summer was achieved if a diet with 3.5 g/kg MET was given, corresponding to a digestible MET intake of 421 mg/d. During winter, maximal egg mass was achieved with a digestible MET intake of 360 mg/d, which was already realised with a MET content of 2.7 g/kg.

Because digestible MET content for maximal egg performance differed between the summer and winter trial, dietary energy to MET ratio might be adjusted to seasonal conditions.

A total of 360 fertile eggs from a broiler breeder strain (Ross 308) were used for in ovo feeding (IOF) of 0, 100 and 200 mg/kg Silybum marianum water extract at 17.5 d of incubation.

After hatching, 240 chicks were transferred to the experimental cages. The diets consisted of two types; one of them without extract and the other one containing 100 mg/kg of Silybum marianum extract. Then chicks were exposed to elevated temperatures 4°C above optimum from 7 to 28 d of age for 4 h per d and after 28 d they were kept at optimum temperature. The chicks were divided into 6 treatments with 4 replicates as a completely randomised 2 × 3 factorial design.

There was no effect of IOF of Silybum marianum extract on hatchability, body weight (BW) of hatched chicks or hatched chick BW/initial egg weight ratio. Chickens fed on the diet containing the extract had the highest feed intake, daily weight gains (DWGs), final BW and lowest feed conversion ratio.

At 28 d, the weights of heart, spleen and bursa of birds in the treatment groups given extract were higher, but abdominal fat weights were lower. At 42 d in those fed extract in the diet, the weights of spleen and bursa were higher and abdominal fat weights were lower than the other groups.

No differences were observed between groups in body temperature before application of the higher temperature but at 21 d and 28 d the body temperature of chicks given the Silybum marianum extract was lower than the other treatments during the elevated temperatures.

In birds fed on the extract in the diet, HDL and cholesterol concentrations were lowest at 28 d, whereas blood glucose levels were higher in the other treatments. At 42 d the cholesterol concentration was significantly lower in birds given extract in their diet.

These results indicated that dietary feeding of Silybum marianum extract resulted in an improvement in performance, immunity and carcass characteristics and decreased the adverse effects of the higher temperatures, specifically in reducing blood fat reduction, but IOF of the extract did not have an effect.

The pharmacokinetics of doxycycline in ducks were investigated after a single intravenous (IV), intramuscular (IM) or oral (PO) dose at 20 mg/kg body weight.

The concentrations of doxycycline in plasma samples were assayed using a high performance liquid chromatography method, and pharmacokinetic parameters were calculated using a non-compartmental model.

After IV administration, doxycycline had a mean (±SD) distribution volume (V_z) of 1761.9 ± 328.5 ml/kg and was slowly eliminated with a terminal half-life (t_1/2λz) of 21.21±1.47 h and a total body clearance (Cl) of 57.51 ± 9.50 ml/h/kg. Following PO and IM administration, doxycycline was relatively slowly absorbed – the peak concentrations (C_max) were 17.57 ± 4.66 μg/ml at 2 h and 25.01 ± 4.18 μg/ml at 1.5 h, respectively. The absolute bioavailabilities (F) of doxycycline after PO and IM administration were 39.13% and 70.71%, respectively.

The plasma profile of doxycycline exhibited favourable pharmacokinetics characteristics in Muscovy ducks, such as wide distribution, relatively slow absorption and slow elimination, though oral bioavailability was low.

Micronutrients, especially zinc, have an important role in normal metabolism and growth of broilers. Using novel technologies helps to synthesise novel zinc complexes to deliver this micronutrient more efficiently.

In the present study, the effects of different zinc complexes and nano complexes on broiler performance were compared. Broilers in 6 groups were given basal diet (without zinc) and basal diet supplemented with zinc-sulphate, zinc-methionine, zinc-nano-sulphate, zinc-nano-methionine and zinc-nano-max (that was synthesised based on nanochelating technology) at a concentration of 80 mg/kg of diet.

At 1–42 d of age, dietary zinc-nano-sulphate supplementation decreased weight gain and feed intake. However, feed conversion ratio was not influenced by treatments. Carcass yield (%) of birds in the zinc-nano-sulphate and control groups were dramatically reduced at 42 d of age and abdominal fat (%) increased in these groups.

Relative to the control group, the antibody titre, spleen and bursa of Fabricius (%) were significantly higher in groups supplemented with zinc. Heterophil (%) was also significantly higher in the zinc-nano-methionine group in blood on d 42 compared to the control, zinc-sulphate and zinc-nano-sulphate.

Compared to the controls, the mean malondialdehyde content in thigh tissue was significantly reduced in groups supplemented with zinc at the time 0, 50, 100 and 150 min after oxidation.

Tibia zinc concentration in nanoparticle zinc samples was significantly higher relative to the control and zinc-sulphate groups.

Taken together, our data indicate that delivery of zinc in the structure of zinc-nano-methionine and zinc-nano-max at concentrations of 80 mg/kg of diet improves growth performance. However, dietary zinc-nano-sulphate decreased growth performance in broilers.