Growth performance,carcass characteristics and meat composition of Milanino chickens fed on diets with different protein concentrations

1. Milanino is a heavy Italian chicken breed included in a conservation project of the University of Milan and is an important genetic resource for alternative production systems. This research was aimed to study the effect of the dietary protein concentration on growth, slaughter performance and meat composition in free-range reared Milanino chickens.

2. A total of 120 Milanino chickens were fed on different protein concentrations (HP = 20% CP and LP = 16% CP), reared according to a free-range system and slaughtered at 150 and 180 d of age. Growth, slaughter performance and meat (breast and thigh) composition were recorded.

3. The protein concentration of the diet did not affect the overall Milanino mean body weight recorded in the straight-run group in the whole rearing period. However, the growth rate within sex was significantly different between the dietary treatments: heavier females were found in the HP group from 125 d onwards, while no differences were recorded in male body weights. The protein concentration of the diet did not affect carcass weight data or meat composition.

4. The present results suggest the use of a low-protein diet for rearing straight-run Milanino chickens for long rearing periods. However, in females, a high-protein diet is recommended from 125 d of age onwards.

     

Melamine residues in eggs of quails fed on diets containing different levels of melamine

1. An experiment was conducted to determine residual melamine concentrations in eggs of quail given diets containing different concentrations of melamine, and to estimate the time at which withdrawing melamine from the diet would result in undetectable concentrations in eggs. A total of 600 Japanese quails (Coturnix coturnix japonica) were randomly divided into 5 treatments, and given melamine at concentrations of 0, 2, 10, 50, and 100?mg/kg diet respectively for 30?d. From d 31 to 41, all quails were given a diet without melamine. Each diet was offered to 4 replicates (cages) of 30 quails each. On d 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, and 41, eggs were collected for the determination of melamine and cyanuric acid levels.

2. Throughout the 41?d experimental period, inclusion levels of melamine in the diets of quails had no significant effect on daily feed intake, egg production percentage, and feed efficiency. No detectable amount of cyanuric acid was found in all eggs. When the diets contained melamine at 2?mg/kg, the amounts of melamine in eggs were below the detection limit. During the entire 30?d exposure, the maximum melamine concentrations in eggs were 0·162, 0·998 and 1·784?mg/kg for the 10, 50 and 100?mg/kg treatment groups, respectively, which demonstrated a linear dose-response relationship.

3. Upon feeding a diet without melamine, the melamine concentration in eggs decreased rapidly. The time taken for the amounts of melamine to decline below the detection limit were 1, 5, and 5?d for quails fed on the diets containing melamine at 10, 50, and 100?mg/kg respectively.

4. Melamine is not metabolised into cyanuric acid in quails, and a positive relationship exists between the concentrations in feed and in eggs.     

Effect of inulin and oligofructose on performance and bone characteristics of broiler chickens fed on diets with different concentrations of calcium and phosphorus

1. In a 6-week experiment with broilers, the effect of diet supplementation, using prebiotic fructans, on the performance and biomechanical and geometrical parameters of the tibia and femur bones was evaluated. 2. A total of 240, 1-d-old, Ross 308 chickens were randomly assigned to 1 of 6 treatments, each comprising 5 replicate cages, with 8 birds (4 male and 4 female) per cage. A 2 x 3 factorial arrangement was employed, with two dietary concentrations of calcium and available phosphorus (standard: 9 x 4/9 x 2 g Ca/kg and 4 x 3/4 x 0 g P available/kg; or reduced: 8 x 3/8 x 1 g Ca/kg and 3 x 7/3 x 5 g P available/kg, for the starter/finisher feeding phases, respectively), and with three diets supplemented by selected prebiotics (none; inulin, 7 x 0 g/kg; oligofructose, 7 x 0 g/kg). 3. The concentration of Ca and available P in the diet had no effect on performance parameters at 21 and 42 d of age. At 42 d, reducing the dietary concentrations of Ca and P significantly decreased such biomechanical parameters of bones as tibia stiffness (by 9 x 2%); and femur breaking strength (by 5 x 8%) and stiffness (by 5 x 1%). The diet with a lower concentration of Ca and P negatively affected such geometrical parameter of the tibia as the cross section area, but had no effect on cortex thickness, or bone weight and length. 4. At 21 or 42 d of age, broilers fed on diets supplemented with inulin or oligofructose displayed a performance similar to those fed on the unsupplemented diet. The prebiotics under study also had no statistically significant effects on the biomechanical and geometrical parameters of either bone. There were no significant Ca and P concentration x prebiotics interaction effects, on either performance parameters or on bone quality indices. 5. It was thus concluded that inulin and oligofructose do not improve the performance and bone quality of broilers, either when fed on diets with a standard concentration of Ca and available P, or with reduced concentrations of these macrominerals.     

Production performance and plasma metabolite concentrations of broiler chickens fed low crude protein diets differing in Thr and Gly

The aim of the study was to test the interaction between Thr and Gly in low crude protein (CP) diets in 7 to 28 d broilers on production performance and plasma metabolites. A total of 2,040 broilers were allocated to 17 treatments. A positive control (PC) diet (20.5% CP) was formulated to be adequate in dietary Thr and Gly. A negative control (NC) diet (18.5% CP, deficient in Thr and Gly) was supplemented with crystalline l-Thr and Gly to obtain a 4 Thr × 4 Gly design. Dietary Thr was tested at an apparent faecal digestibility (AFD) Thr-to-Lys ratio, which was 55%, 58%, 61% or 64%, and dietary Gly was tested at an AFD (Gly + Ser)-to-Lys ratio, which was 135%, 142%, 149% or 156%. Plasma samples were collected at 28 d. The low CP diet, formulated at 64% Thr and 156% Gly, resulted in a higher body weight gain (BWG) (P < 0.01) and similar feed conversion ratio (FCR) as the high CP treatment (PC). FCR was improved (P < 0.001) by l-Thr supplementation. Quadratic response to dietary Thr was significant for feed intake (FI), BWG and FCR (P < 0.01). A near-significant interaction for Thr × Gly was observed for FI and BWG (P_linear = 0.091 and P = 0.074, respectively). Gly did not affect production performance. An interaction between Thr × Gly on plasma free AA level was observed (P < 0.05). Free AA concentration in plasma linearly decreased with increase in AFD Thr-to-Lys ratio, and increased with increase in AFD (Gly + Ser)-to-Lys ratio. Plasma uric acid concentration was higher in PC than in all of the other diets, and plasma triglyceride concentration was decreased by l-Thr supplementation, but not by Gly. In conclusion, Gly was not limiting for growth at low dietary CP level unless Thr was deficient, showing that adequate amounts of Thr in broiler diets can overcome marginal supply of Gly and Ser and allow reduction of dietary CP from 20.5% to 18.5% for broilers from 7 to 28 d of age.     

The efficiency of energy retention of broiler chickens and turkeys fed on diets with different lysine concentrations

1.?An experiment determined the effect of 6 different lysine concentrations (40, 52, 58, 65, 90 and 130 g/kg CP) in two protein concentrations (210 and 260 g/kg) on the efficiency of energy utilisation of broiler chickens and turkeys. Ninety-six male Ross 308 broiler chicks and 96 male BUT Big 6 turkey poults were fed at 90% of ad libitum during a 12 d bioassay period. At the end of the bioassay, birds were slaughtered and carcase crude protein, fat and gross energy were measured and nutrient metabolisability determined.

2.?Broiler chickens had lower AME and AME_N than turkeys. AME was higher in the 260 g/kg than in the 210 g/kg protein diet; however, no difference was evident in AME_N between any of the diets in both species. A significant species × lysine interaction indicated that the decrease in AME and AME_N with increasing lysine was greater in turkeys than in broiler chickens.

3.?Turkeys had lower weight gains and efficiencies of energy retention than broiler chickens. The effects of different lysine concentrations on growth and the efficiency of energy retention were significant and growth responses were quadratic but there were negative linear responses in the efficiency of energy retention in both species at both crude protein concentrations. The efficiency of energy retention was increased with decreasing lysine concentrations throughout the wide range of concentrations used in the experiment.     

黄曲霉毒素B1分解酶对肉牛生长性能、胴体品质及毒素组织残留的影响

选取30头体质量344kg左右健康西门塔尔杂交牛,随机分为3组:对照组,饲喂基础饲粮;试验Ⅰ组和Ⅱ组分别在基础饲粮基础上添加0.05%和0.10%的黄曲霉毒素B1分解酶,试验期90d。结果表明:各组之间生长性能、胴体指标、血液和肝脏生化指标差异不显著(P0.05);添加黄曲霉毒素B1分解酶显著降低了毒素在肝脏(P0.01)和肾脏(P0.05)中的残留。试验Ⅰ、Ⅱ组肝脏黄曲霉毒素的B1残留量分别比对照组下降了44.87%(P0.01)和49.15%(P0.01);试验Ⅰ、Ⅱ组肾脏中黄曲霉毒素的B1残留量分别比对照组下降了32.20%(P0.05)和33.90%(P0.05)。由此可知,肉牛饲料中添加黄曲霉毒素B1分解酶可降低毒素在组织中的残留。     

Growth performance and intestinal morphology of Hyline chickens fed diets with different diet particle sizes

The effect of feed particle size on the growth performance and intestinal morphology of Hyline chickens was studied. Sixty one‐day‐old chickens were randomly assigned into two groups with five replicates per group and six chickens per replicate. The control group (CG) was fed pelleted feed and the experimental group (EG) was fed crumbled feed. The geometric mean diameter (GMD) of the pelleted and crumbled feed was approximately 1.2 and 0.8 mm respectively. The trial was carried out from day 15 to day 69 of the lives of the chickens. During the experimental period, the average daily feed intake (ADFI), average daily gain (ADG) and feed conversion rate ( FCR) were calculated. At 42 and 69 days of age, fifteen chickens from each group were slaughtered for the intestinal morphology analyses. The morphologies of various segments of the intestine were observed by scanning electron microscopy (SEM). The results showed that from 15 to 42 days of age, the FCR of the CG was higher than that of the EG, but the final body weight was lower in the CG than in the EG (p < 0.05). The villi heights in the duodenum, jejunum and ileum were shorter in the CG than in the EG (p < 0.05). The villi tips in the duodenum and jejunum of the CG were broken, but they were protected in the EG. At 69 days of age, the BW and the whole intestinal villi height of the CG were greater than those of the EG (p < 0.05). The villi in the duodenum and jejunum in the CG were better than 42 days, but the tips of the duodenal villi in the EG were slightly broken. In conclusion, feeding chickens crumbled feed from 15 to 42 days of age and then feeding them pelleted feed was beneficial to the growth performance of the Hyline chickens, as the pelleted feed would break the intestinal villi of young chickens, but the intestinal villi become stronger with the chicken growth.     

Ultrastructure of hepatic and renal lesions in chickens fed aflatoxin

Male broiler chicks were given feed and water ad libitum from hatching through 3 weeks of age. The feed contained 0, 1.25, 2.5, and 5.0 micrograms of aflatoxin/g of feed. The chicks were killed by cervical dislocation and specimens of liver and kidney were obtained for electron microscopy on days 3, 6, 9, 17, and 21. In chicks fed 5.0 micrograms of aflatoxin, the primary lesions in liver were hepatocellular lipidosis, enlargement of bile canaliculi, reduction in mitochondrial size, mild lymphocytic infiltration, and hepatocellular degeneration and necrosis. Similar lesions were noticed in some chicks fed 2.5 micrograms of aflatoxin, but none was observed in chicks fed at 1.25 micrograms of aflatoxin. At 5 micrograms of aflatoxin, the most consistent lesion in the kidney was thickening of the glomerular basement membrane. Similar glomerular lesions were observed at 2.5 micrograms of aflatoxin, but not at 1.25 micrograms of aflatoxin. Some foot processes of the glomerular epithelial cells were poorly developed. Fusion of foot processes was not observed and fibrous material was not evident in the basement membrane. The pseudopodia of endothelial cells lining the thickened basement membrane were depleted in number or were absent. Degenerative changes also were observed in the cells of the proximal convoluted tubules, but these were less consistent than those of the glomerulus.     

Evaluation of diets contaminated with aflatoxin and ochratoxin fed to growing pigs

The effects of dietary aflatoxin and ochratoxin, fed singly and in combination, were evaluated in growing crossbred pigs. Five barrows (7 weeks old at beginning of study) per group were fed either control feed, 2.0 mg of aflatoxin (AF)/kg of feed, 2.0 mg of ochratoxin (OA/kg of feed, or 2.0 mg of AF and 2.0 mg of OA/kg of feed for 28 days. Production performance, serum biochemical, hematologic, and pathologic evaluations were made. Body weights were reduced by the combination treatment, whereas body weight gain was decreased by all toxin treatments. The effect of AF and OA in combination on body weight gain was additive. Liver weights were increased by the combination treatment, whereas kidney weights were increased only in the OA group. Aflatoxin caused decreases in serum calcium, sodium, phosphorus, urea nitrogen, cholesterol, and glucose concentrations, whereas OA alone caused decreases in serum phosphorus, cholesterol, and hematologic values. The AF-OA treatment induced decreases in mean corpuscular volume, packed cell volume, and in serum concentrations of phosphorus, cholesterol, and urea nitrogen. The AF-OA treatment increased serum alkaline phosphatase activities and triglycerides. It was concluded that AF and OA, singly or in combination, can affect clinical performance, serum biochemical and hematologic values, and organ weights of barrows. Although values of some measurements were affected more by the combination than by either toxin alone and suggested synergism or antagonism, the toxic interactions could best be described as additive.     

Influence of the dietary ratio between sulphur containing amino acids and lysine on performance of growing-finishing pigs fed diets with various lysine concentrations.

This study was conducted to determine the optimal ratio between sulphur containing amino acids and lysine in diets for growing-finishing pigs. Therefore, a total of five trials was carried out in which growing-finishing pigs (live weight range between 53 and 105 kg) were fed diets with various concentrations of lysine (0.62, 0.70 and 0.78%) and various ratios between sulphur containing amino acids to lysine. The diets contained 12.9 MJ ME per kg and 13.5% CP; the ratio between sulphur containing amino acids to lysine was adjusted by individual supplementation of the diets with DL-methionine. Increasing dietary levels of lysine from 0.62 to 0.78% continuously increased daily body weight gains and improved feed conversion efficiency as well as carcass characteristics. There was no significant interaction between the dietary lysine supply and the ratio between sulphur containing amino acids to lysine on animal performance parameters. This means that the effect of the ratio of sulphur containing amino acids to lysine was similar for various dietary lysine concentrations. The optimum ratio between sulphur containing amino acids to lysine according to quadratic regression analysis was 0.60, for both, growth and feed conversion. Reducing the ratio between sulphur containing amino acids to lysine from 0.59 to 0.53 and 0.47 reduced body weight by 3 and 12%, resp., and elevated the feed conversion ratio by 2 and 12%, resp. An increase of the ratio between sulphur containing amino acids to lysine from 0.59 to 0.65 failed to increase the animal performance. In contrast to animal performance parameters, optimum carcass characteristics (eye muscle area, fat area above eye muscle, meat-fat ratio and lean percentage) were achieved already at a ratio of sulphur containing amino acids to lysine of 0.53.     

Probiotic preparation reduces the faecal water genotoxicity in chickens fed with aflatoxin B1 contaminated fodder

The aim of the study was to evaluate the influence of a probiotic preparation on the genotoxicity of faecal water of broiler chickens fed with a fodder contaminated with aflatoxin B₁ (AFB₁) at 1 or 5 mg per kg. Human blood lymphocytes were exposed to chicken’s faecal water samples and DNA damage was measured using the comet assay. Genotoxicity of faecal water did not depend on the AFB₁ concentration in the fodder. The mean DNA damage, measured as the percentage of DNA in the tail of the comets, for chickens fed with fodder with AFB₁ at 1 mg/kg was 16.80 ± 0.66, at 5 mg/kg – 16.73 ± 1.51 and in the controls – 12.79 ± 0.66. The supplementation of fodder with the probiotic preparation decreased the extent of DNA damage to 10.02 ± 0.39 for 1 mg/kg AFB₁ and to 11.89 ± 0.72 for 5 mg/kg.     

Influence of sand and grit on the performance of turkey poults fed on diets containing two concentrations of protein 1

1. Growth rate and the efficiencies of food and energy utilisation were investigated with large white poults. They were fed from 1 to 3 weeks of age on diets containing either 240 or 300 g crude protein/kg diet, with no filler, 25 g washed builders’ sand/kg or 25 g chick‐size grit/kg.

2. Sand and grit increased growth and improved the food and energy conversion ratios. None of the interactions of crude protein content with filler was statistically significant.

3. It is speculated that grit and sand improved the grinding and the digestion of the food particles.     

Combined effects of clenbuterol and various concentrations of protein on performance of broiler chickens

1. The effects of the beta-adrenergic agonist, clenbuterol (1 mg/kg diet) on the growth and muscle composition in female broiler chickens (14 to 32 d of age) fed on diets containing various concentrations of protein (220, 240 or 260 g protein/kg) were examined. 2. Body weight gain over the 18 d period increased linearly with increasing protein intake. The rate of gain was significantly higher in clenbuterol-treated chickens than in control birds. 3. Dietary clenbuterol increased thigh muscle weight and protein concentration of breast and thigh muscle, regardless of dietary protein content. Protein/DNA ratio in thigh muscle was enhanced by clenbuterol feeding, and the magnitude of difference of the ratio was higher in chickens fed on the 240 and 260 g CP/kg diets than in those fed the 220 g CP/kg diet. 4. It was concluded that clenbuterol-treated chickens require increased dietary protein to maintain maximal growth, and that increased protein consumption is an important factor in improving growth in clenbuterolfed broilers.     

A Saccharomyces cerevisiae RC016-based feed additive reduces liver toxicity,residual aflatoxin B1 levels and positively influences intestinal morphology in broiler chickens fed chronic aflatoxin B1-contaminated diets

The present study was conducted to investigate the ability of Saccharomyces cerevisiae RC016 (Sc)-based feed additive to reduce liver toxicity, residual aflatoxin B₁ (AFB₁) levels and influence intestinal structure in broiler chickens fed chronic aflatoxin B₁-contaminated diets. A total of 100 one-day-old male commercial line (Ross) broiler chickens were divided into 4 treatments, with 5 pens per treatment and 5 broiler chickens per pen. Birds were randomly assigned to 4 treatments, which were namely treatment 1 (T₁), control diet (CD); T₂, CD + Sc at 1 g/kg; T₃, CD + AFB₁ at 100 μg/kg; T₄, CD + Sc at 1 g/kg + AFB₁ at 100 μg/kg. The liver histopathology of broiler chickens fed diets with AFB₁ showed diffused microvacuolar fatty degeneration. The addition of Sc showed normal hepatocytes similar to the control. The small intestine villi from AFB₁ group showed atrophy, hyperplasia of goblet cells, prominent inflammatory infiltrate and oedema. In contrast, the small intestine villi from birds that received the yeast plus AFB₁ showed an absence of inflammatory infiltrate, and atrophy; moreover, a lower number of goblet cells compared to the groups with AFB₁ was observed. The morphometric intestine studies showed that a significant decrease (P < 0.05) in the crypt depth values when Sc was applied to AFB₁-contaminated diets. Although the intestinal villus height and apparent adsorption area did not show significant differences (P > 0.05), there was a tendency to improve these parameters. The residual levels of AFB₁ in livers were significantly reduced (P < 0.05) in the presence of the yeast. The present work demonstrated that the addition of Sc alone or in combination with AFB₁ in the broiler chicken diets had a beneficial effect in counteracting the toxic effects of AFB₁ in livers besides improving the histomorphometric parameters and modulating the toxic effect of AFB₁ in the intestine.     

Calcium and phosphorus utilisation in chickens fed on diets high in N-alkane-grown yeast

Interactions between calcium (Ca) and phosphorus (P) were studied in young chickens fed on diets high in n-alkane-grown yeast and in chicks fed on control soya-fishmeal diets for 14 d. Additions of inorganic Ca to diets containing 300 g yeast/kg caused increases in body-weight gain, gain:food ratio and bone mineralisation up to a total dietary concentration of 13.9 g Ca/kg. At all additions of Ca, bone mineralisation was inferior in yeast-fed chicks compared with control chicks. Supplementation of high Ca diets (16.8 g Ca/kg) with inorganic P led to further improvements in body-weight gain, food intake and food utilisation of chicks fed on high-yeast diets. Bone mineralisation also improved but was always inferior in the yeast-fed chicks compared with control chicks. It was concluded that Ca and P supplementation was necessary in high-yeast diets due to low dietary Ca concentrations and low availability.     

Calorimetric measurements on chickens given diets with a range of energy concentrations

Eight diets with metabolisable energy (ME) concentrations ranging from 9–1 to 15–3 MJ/kg were given to groups of five chickens kept in respiration calorimeters for 3 to 4 d. Availability of ME ranged from 57% to 79%. One diet differed from the others, but for those groups of chickens on the other seven diets availability of ME was 80% when energy balance was negative and only 60% when positive.

Protein synthesis appeared to continue when chickens were in negative energy balance and fat was frequently catabolised when birds were in positive energy balance, apparently to support protein synthesis.     

Blood vitamin concentrations in privately owned dogs fed non-standardized commercial diets and after intake of diets with specified vitamin concentrations

The objective was to investigate in a survey study the blood vitamin concentrations in healthy dogs fed non-specified commercial complete diets and in an intervention study to determine the effects of defined dietary vitamin intakes on blood vitamin levels and hair and skin condition. Sixty-four privately owned dogs, aged from 1 to 8 years, without history of skin or coat problems were included. All animals were fed commercial complete diets with uncertain vitamin concentrations before enrolment. The animals were assigned, according to weight and gender, to four groups with graded vitamin intakes. The blood vitamin levels and skin and coat quality of the dogs were investigated at days 0 and day 122. Coat and hair condition was not influenced by the experimental diets. The retinol concentrations were reduced at the end of the experiment compared with the baseline levels, retinyl esters were not influenced. 25-Hydroxycholecalciferol decreased in all groups, alpha-tocopherol was constant or tended to decrease. Ascorbic acid, thiamine pyrophosphate and riboflavin concentrations were not affected by treatment, flavin adenine dinucleotide and pyridoxal-5'-phosphate were partially reduced on day 122. Cobalamin, pantothenate and biotin concentrations increased with higher dietary intakes, folate levels in tendency. In conclusion, this study gives a survey of blood vitamin concentrations in healthy dogs and provides a data base for the evaluation of the vitamin status in health and disease.