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.

     

Effects of concentrate feeding systems,genotype and sex on productive performance and meat quality of Norwegian lambs

Abstract

Two factorial experiments, I and II, were carried out in this study using 84 lambs (140±1.24 days old, 40.00±0.75 kg live weight) divided into six groups. Two levels of concentrate supplementation; restricted (0.4 kg concentrate/lamb/day) or ad libitum, two breed types; Norwegian White lamb or Nor-X and two sex types; ram or ewe lambs, were investigated. In experiment I, a 2×2×2 factorial arrangement of treatments (level of supplementation, sex, and breed) was imposed whereas a 2×2 arrangement of treatments (level of supplementation and breeds) was studied in Experiment II. Each of the two experiments lasted for four weeks. Lambs on ad libitum access to concentrate grew at 231 g d^–1 and 125 g d^–1 faster than those on restricted access in Experiment I and II, respectively. Moreover, ram lambs grew at 64 g d^–1 faster than ewe lambs. Lambs on ad libitum access to concentrate had about 5 kg heavier carcasses than that on restricted access. Ewe and ram lambs on ad libitum allowance to concentrate had 4.2 kg and 5.6 kg, respectively, higher carcass weight than those on restricted allowance. The two levels of concentrate supplementation had limited effects on the meat sensory qualities. Meat taste intensity increased with level of concentrate supplementation. Difference in meat tenderness between ram and ewe lambs was only evidenced on ad libitum concentrate feeding. Irrespective of stage of growth (Experiment I vs. II) and concentrate supplementation level, Nor-X lambs were superior to Norwegian White lambs with respect to carcass conformation scores. Based on results from sensory assessments of meat, ram lambs should be slaughtered before October to avoid off-flavour on meat.     

Meat quality of fully or partly outdoor reared pigs in organic production

Abstract

Outdoor production on pasture is considered an option in organic pig production. The aim of the present trial was to study the influence of feeding strategies combining outdoor and indoor rearing on pig meat quality. The experiment was carried out with 245 pigs in 5 replicates, and commenced following weaning at day 52. Five treatments were compared: 1) pigs fed ad libitum and reared indoors with access to an outdoor concrete area (In-A); 2) pigs fed restrictively on pasture until 40 kg body weight and then kept indoors with access to an outdoor concrete area and fed ad libitum until slaughter (In-40A); 3) pigs fed restrictively on pasture until 80 kg body weight and then kept indoors with access to an outdoor concrete area and fed ad libitum until slaughter (In-80A); 4) pigs reared on pasture and fed restrictively during the whole period of growth (Out-R); and 5) pigs reared on pasture and fed ad libitum during the whole period of growth (Out-A). All pigs had free access to roughage (clover-grass silage/fresh clover grass). Restrictive feeding in the weight range from weaning to 40 kg body weight (In-40A) resulted in a reduced daily gain; however, following transfer to indoor facilities and ad libitum feeding these pigs compensated in growth and the overall daily gain did not differ from the In-A control pigs. Pigs fed restrictively from weaning to 80 kg body weight were unable to compensate completely following transfer to indoor facilities. Out-R pigs had the lowest overall daily gain, while In-A pigs and Out-A pigs had similar daily gain. Meat quality assessments were performed on longissimus dorsi (LD) samples from a subsample of 100 pigs (2 castrates and 2 female pigs from each treatment in each replicate). Compared to meat from either ad libitum treatments (In-A and Out-A), meat from Out-R and In-80A pigs was less red due to a lower pigmentation, and had a higher ratio of polyunsaturated:saturated fatty acids. In addition, Out-R female pigs had numerically (6–10 Newton) higher shear force than In-A and Out-A. Treatments did not affect the concentration of α-tocopherol of meat. Introducing a finishing period with free access to concentrates following 40 kg body weight until slaughter prevented the deterioration in meat quality. However, a finishing period following 80 kg body weight was not sufficient. In conclusion, ad libitum feeding in the organic production system gave superior meat quality compared to a restrictive feeding strategy. However, including a finishing period indoors with ad libitum feeding of concentrates may prevent the detrimental effect of restrictive feeding on meat quality.     

Interaction of transport distance and body weight on preslaughter stress and breast meat quality of broilers

1. The objective of the study was to investigate the effect of transport distance on blood metabolites and breast meat quality of broilers slaughtered at different weights.

2. The study was conducted on Ross 308 broilers from 27 different flocks reared under similar conditions. Slaughter weight was classified as <2·0?kg, 2·0–2·4?kg, and >2·4?kg. Transport distance was categorised as short (65?km), medium (115?km) and long (165?km) distance representing 90, 155 and 220?minutes at an average 45?km/h speed, for each slaughter weight.

3. Higher heterophils and heterophil:lymphocyte (H/L) ratios were obtained for broilers transported over a long distance. Long distance transport increased blood albumin, glucose, and triglycerides levels for <2·0?kg broilers, which did not differ from broilers slaughtered at >2·4?kg after long-distance transport.

4. Broilers slaughtered at >2·4?kg after long-distance transport had lower pH_u, and paler and tougher breast meat, than those broilers slaughtered at <2·0?kg after long-distance transport.

5. A negative correlation was obtained between pH_u and L*, thawing loss and texture. The L* value was negatively correlated with a*; and positively correlated with b*, thawing and cooking losses.

6. It was concluded that the effect of transport distance could not be evaluated independently of slaughter weight. The interaction between transport distance and slaughter weight contributes to preslaughter stress and meat quality.     

Energy requirements of early‐weaned Dorper cross‐bred female lambs

The net and metabolizable energy (NE and ME) requirements of Dorper cross‐bred female lambs with BWs of 20–35 kg were assessed in a comparative slaughter trial. Thirty‐five Dorper × thin‐tailed Han cross‐bred female lambs weaned at ~50 days of age (20.3 ± 2.15 kg BW) were used. Seven randomly selected lambs were slaughtered at the start of the trial (baseline group). An intermediate group consisting of seven randomly selected lambs fed ad libitum was slaughtered when the lambs reached an average BW of 28.5 kg. The remaining 21 lambs were allotted randomly to three levels of dry matter intake: ad libitum or restricted to 70% or 40% of the ad libitum intake. All the lambs were slaughtered when the sheep fed ad libitum reached a BW of 35 kg. Total body energy, nitrogen, fat, ash and moisture content were determined. In a digestibility trial, an additional 15 Dorper × thin‐tailed Han cross‐bred female lambs (28.7 ± 1.75 kg BW) were housed in metabolism cages and used in a completely randomized design experiment to evaluate the ME value of the diet at the three feed intake levels. The maintenance requirements for NE and ME were 245.5 and 380.3 kJ/kg metabolic shrunk body weight (SBW^0.75) respectively. The partial efficiency of energy use for maintenance was 0.645. The NE requirements for growth ranged from 1.18 to 5.18 MJ/d for the lambs gaining 100–350 g/d from 20 to 35 kg BW. Partial efficiency of ME for growth was 0.44. In conclusion, the current study suggests that the NE requirement for maintenance and growth of Dorper early‐weaned cross‐bred female lambs is lower than the current AFRC and NRC recommendations.     

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.     

Oral administration of lysine restores food intake and ventromedial hypothalamic dopamine in chicken on a lysine-free diet

1. This study was conducted to examine whether oral administration of lysine solution affect food intake and the ventromedial hypothalamic (VMH) monoamines in chickens fed on a lysine-free diet.

2. Chickens were assigned to four treatment groups. Two groups of chickens were given two different doses of lysine solution (0·1?g and 0·07?g in 1?ml of saline) exogenously (orally) while being fed on a lysine-free diet, and these results were compared with a control diet plus saline group. Another group of chickens was fed on a lysine-free diet without lysine supplementation, and their results were compared with the lysine treated groups. The extracellular dopamine (DA), norepinephrine (NE) and serotonin (5-HT) in the VMH of freely moving chicken were measured by in vivo microdialysis.

3. There was no significant difference in food intake between the control diet and the lysine supplemented groups during the time-course of the experiments. Food intake significantly decreased at 4, 5 and 6?h in the lysine-free diet plus saline group compared with the lysine supplemented groups. Of the VMH monoamines, the DA concentration remained close to the baseline in the lysine supplemented groups. This DA concentration was significantly lower than the baseline in the lysine-free diet plus saline group at 3·5?h and thereafter.

4. No significant difference from the baseline was observed for NE in the lysine-free diet plus saline group. The 5-HT concentrations were close to the baseline for all groups throughout the experiments.

5. The findings suggest that oral administration of lysine solution to chickens fed on a lysine-free diet restored food intake which was associated with the variations of VMH DA concentration.     

Rice bran lysolecithin as a source of energy in broiler chicken diet

1. Rice bran lysolecithin (RBL) was evaluated in broiler chicken diets. In the first experiment, RBL was included in diet at 0, 0·5, 2, 8 and 32?g/kg and fed to 250 broiler chickens from 0 to 42?d of age. In the second experiment, RBL was fed at 0, 25 and 50?g/kg diet to 405?day-old broiler chickens until 21?d of age, while during the finisher phase (22–35?d of age) chickens receiving each concentration of RBL were given all three concentrations of RBL in a 3?×?3 factorial manner. The diets were isocaloric.

2. Body weight, food consumption and food conversion efficiency were unaffected by feeding RBL, while the weight of pancreas increased at ≥2?g/kg of RBL in diet (experiment 1). In experiment 2, body weight was greater in the chickens receiving RBL at either 25 or 50?g/kg (21?d) and 50?g/kg (35?d of age). At 21?d of age, food consumption was greater at 25 or 50?g RBL/kg diet, while food conversion efficiency improved with 50?g RBL/kg diet.

3. Fat digestibility increased with RBL at 32?g/kg (experiment 1) and ≤25?g/kg (experiment 2). Rice bran lysolecithin increased ready to cook weight at 50?g/kg during starter phase and decreased abdominal fat at 25 and 50?g/kg during finisher phase (experiment 2). Liver and meat fat content were not affected.

4. It is concluded that lysolecithin from rice bran oil could be used as energy supplement in broiler chicken diet.     

Bovine metacarpal and metatarsal dimensions: Comparison of aberdeen—Angus and charolais steers slaughtered at three percentages of mature cow weight

Fifty-six Aberdeen—Angus (Angus) and 56 Charolais steers were used in a 2 (diet energy levels) × 4 (slaughter weights) × 2 (breeds) factorial experiment. Live slaughter weight groups within each breed were initial, 86 (light), 100 (middle) or 114% (heavy) of average mature cow weight (Angus dams, 467 kg; Charolais dams, 612 kg). Therefore, Angus were slaughtered at 408, 476 or 544 kg and Charolais at 526, 612 or 699 kg. Live, carcass and metacarpal and metatarsal traits were obtained. There were no important effects of diet (2.72 vs. 2.96 Meal metabolizable energy/kg of dry matter). Breed affected (P < 0.01) live body measurements in each slaughter weight group except in initial groups. Within initial groups, breed affected (P < 0.01) live fore- and rear-cannon lengths and wither height. Mean limb-bone weight, expressed as a percentage of live weight, was greater for Charolais than for Angus in each weight group. Bone length increases ceased within Angus between initial- and light-weight slaughter endpoints, but ceased in Charolais between light and heavy groups. Bone area and circumference increased through most weight increments for both breeds, confirming that appositional bone growth continues after length increases cease. Bone specific gravity was maximized in the middle-weight Angus, but increased (P < 0.01) between middle and heavy Charolais. Generally, these results indicate that bone growth subsides earlier and ossification is more advanced in Angus than in Charolais if both breeds are slaughtered at the same percentages of mature weight.     

Performance,carcass and technological meat quality of pigs in indoor and outdoor production systems

Abstract

This study aimed to compare different production systems, i.e., the combined effect of outdoor and indoor rearing of pigs and organic diets fed ad libitum or restrictively. Furthermore, the suitability of two breed crosses for outdoor rearing was studied. The effects on performance, carcass and technological quality traits were investigated. During two years, 240 pigs of Duroc x Large White (D*LW) and Swedish Landrace x Large White (L*LW) were allocated to three production systems: 1) Pigs kept outdoors, fed an organic diluted diet (20% alfalfa roughage) ad libitum; 2) Pigs kept outdoors, strategically fed a diluted organic diet up to a live weight of approximately 80 kg and thereafter an undiluted organic diet ad libitum; 3) Pigs kept indoors, fed an undiluted organic diet restrictively. For outdoor pigs, strategic feeding increased daily weight gain and backfat thickness, compared with feeding a diluted diet throughout (p≤0.01). L*LW pigs in both outdoor systems grew slower than in the indoor system (p≤0.001), whereas for D*LW pigs only outdoor pigs fed the diluted diet had a slower growth rate. Outdoor pigs had lower dressing percentage than indoor pigs. Glycogen content and L* values in M. longissimus dorsi were higher, whereas b* values were lower in meat from pigs in the indoor system. D*LW pigs had higher water-holding capacity (lower drip, thawing and cooking losses), lower shear force and higher intramuscular fat content compared with L*LW pigs.     

Conditioning time and sodium bentonite affect pellet quality,growth performance,nutrient retention and intestinal morphology of growing broiler chickens

ABSTRACT

1. The present study was conducted to evaluate the effects of conditioning times and processed sodium bentonite (PSB)-based pellet binder (G. Bind?) on pellet quality, performance, small intestine morphology, and nutrient retention in growing broiler chickens (d 11–24).

2. A total of 540, one-day-old male broiler chicks were fed a commercial starter diet (d 1–10). On day 11, birds were assigned to a 2 × 3 factorial arrangement including two conditioning times (2 and 4 min) and three levels of PSB (0, 7.5 and 15 g/kg) with six replicates of 15 chicks each. Feed intake and weight gain were recorded to calculate growth performance. The jejunal segment and excreta samples were collected to determine intestinal morphology and nutrient retention, respectively.

3. Diets produced with 2 min conditioning time and containing 15 g/kg PSB increased (P < 0.05) pellet durability index and hardness. Conditioning time and PSB levels had no significant effect on growth performance. The inclusion of PSB to broilers diet increased (P < 0.05) energy usage of the pelleting machine. Chickens fed the diet conditioned for 2 min and containing 15 g/kg PSB had the lowest (P < 0.05) relative jejunal length. Two minutes conditioning of diets containing 15 g/kg PSB increased (P < 0.05) apparent metabolisable energy retention in broilers.

4. It was concluded that 2 min conditioning of diet containing 15 g/kg PSB improved pellet quality and nutrient retention of broiler chickens, while the main effects of conditioning time and PSB levels were controversial in most evaluated parameters.     

Subsequent growth performance and digestive physiology of broilers fed on starter diets containing spray-dried porcine plasma as a substitute for meat meal

1. A 4 × 2 factorial experiment was conducted to investigate the effect of inclusion of spray-dried porcine plasma (SDPP), in lieu of meat meal, in the starter diet on performance and digestive physiology of broiler chickens between hatch and 35 d of age. Four levels of SDPP (0, 5, 10 or 20 g/kg) were included in the starter diets in lieu of meat meal on either wheat- or maize-based diets.

2. Over the first 10 d, and throughout the 35-d experimental period, birds gained more body weight with increasing concentrations of SDPP regardless to the type of grain used. Inclusion of SDPP in the starter diet markedly improved feed per gain in the starter phase and across the 35-d study. There was no significant effect of the type of grain and its interaction with SDPP on the body weight gain and feed per gain for the two assessed periods.

3. At d 10, the relative weight of the gizzard+proventriculus, spleen and liver increased with increasing concentrations of SDPP.

4. At 24 d of age, the grain and SDPP inclusion significantly interacted, depressing the weight of bursa and spleen in birds that received the highest concentration of SDPP in the maize-based diet. Birds fed on the maize-based diets had higher relative weight of pancreas than those on the wheat-based diets.

5. Increasing concentrations of SDPP in the starter diet improved the activities of maltase, sucrase and alkaline phosphatase at 24 d of age. The interaction of grain and SDPP concentration was significant for sucrase activity in birds on the wheat-based diets. Chickens on maize-based diets had higher alkaline phosphatase and maltase activities than those on wheat-based diets.

6. Chicks that were offered SDPP-containing starter diets had longer villi, deeper crypts and lower villi/crypt than the control at 24 d of age regardless of the grain type used. Furthermore, longer villi and larger villi/crypt were found in chicken groups fed on wheat-based diets than those on maize-based diets.

7. Chickens on maize-based diets had higher dressing percentage and relative breast weight than those on wheat-based diets at 35 d of age.

8. It can be concluded that supplementation of starter diets with SDPP would be beneficial to the long-term growth of broiler chickens. The effect of the basal grain used in the diet is minimal.

     

The effects of temperature on broilers: A simulation model of the responses to temperature

1. The effects of post‐brooding temperature (15 to 27 °C), age (42 to 56 d) and dietary nutrient and concentration energy (11.7 to 13.3 MJ/kg for the finisher diet) on the cumulative food intake and body weight responses of broilers were combined in a predictive simulation model, using multiple regression techniques.

2. An economic model of these responses was developed in which the temperature and age at slaughter are optimised, given food and live body weight prices.

3. If a finisher diet of 13.3 MJ ME and 199 g protein/kg costing 150 £/tonne is fed, and provided the grower diet contains 13.5 MJ and 221 g protein/kg, the optimum temperature is 21 to 22 °C for male and female broilers slaughtered at 61 and 54 d respectively with a live body weight value of £0.50/kg.     

Free-range pigs foraging on Jerusalem artichokes (Helianthus tuberosus L.) – Effect of feeding strategy on growth,feed conversion and animal behaviour

Abstract

The nutritional contributions from free-range foraging, growth, feed conversion and behaviour were investigated in 36 growing pigs foraging on Jerusalem artichokes (JA) and fed concentrates restrictedly (30% of energy recommendations) or ad libitum. Compared to the ad libitum fed pigs, the pigs fed restrictedly had a significant lower daily gain (560 vs. 1224 g pig^?1), improved feed conversion ratio (17.6 vs. 42.8 MJ ME concentrate kg^?1 live weight gain) and spent more time foraging JA tubers (7.9 vs. 1.1%). It is estimated that pigs fed restrictedly found approximately 60% of their energy requirement from foraging in the range.     

Effects of sex and inclusion of dried distillers grains with solubles on slaughter yield and meat characteristics of Pekin ducks

1. The effects of dried distillers grains with solubles (DDGS) dietary inclusion concentration, and sex, on body weight, slaughter efficiency and meat characteristics of Pekin ducks (Anas platyrhynchos f. domestica, strain P55) were studied.

2. Sexed ducklings (n?=?160) were divided randomly into 4 groups (each with 4 replicates). From d 1 to d 21, all the birds received the same commercial feed, then from 22 to 49 d of age the ducks were fed in the following groups: control (commercial feed) and three experimental groups (15%, 25% and 30% inclusion of DDGS). All ducks were weighed individually at d 1, 21 and 49. On the day of slaughter, 5 males and 5 females, of body weight close to the average weight for group and sex, were selected from each group, slaughtered and the following parameters were evaluated: slaughter yield, weight, and percentage of particular elements of carcase, physical and chemical characteristics of meat.

3. The results obtained showed that DDGS included from 22 to 49 d of rearing, at concentrations up to 30%, in a commercial Pekin duck diet did not affect the live body weight, slaughter yield, weight, and percentage of breast and leg muscle, skin with subcutaneous fat, and abdominal fat. There were no differences in physical characteristics (pH₁₅, pH_24, meat colour values L*, a*and b*, and hygroscopicity) of breast muscle, as well as in cholesterol content. DDGS addition at 30% significantly increased fat content in male, and crude protein in female, breast meat. Sex effect was observed only in a few traits and was diet dependent. Final body weight of females fed 30% DDGS was significantly lower than males; in the control and 15% DDGS group females had higher percentage of skin with subcutaneous fat.

4. The results obtained, and relative costs of feeds produced, allows the recommendation of DDGS addition at up to 30% to commercial Pekin duck diets from 22 d of age.     

Growth and haematological response of indigenous Venda chickens aged 8 to 13 weeks to varying dietary lysine to energy ratios

The effect of feeding varying dietary lysine to energy levels on growth and haematological values of indigenous Venda chickens aged 8 – 13 weeks was evaluated. Four hundred and twenty Venda chickens (BW 362 ± 10 g) were allocated to four dietary treatments in a completely randomized design. Each treatment was replicated seven times, and each replicate had fifteen chickens. Four maize–soya beans‐based diets were formulated. Each diet had similar CP (150 g/kg DM) and lysine (8 g lysine/kg DM) but varying energy levels (11, 12, 13 and 14 MJ ME/kg DM). The birds were reared in a deep litter house; feed and water were provided ad libitum. Data on growth and haematological values were collected and analysed using one‐way analysis of variance. Duncan's test for multiple comparisons was used to test the significant difference between treatment means (p < 0.05). A quadratic equation was used to determine dietary lysine to energy ratios for optimum parameters which were significant difference. Results showed that dietary energy level influenced (p < 0.05) feed intake, feed conversion ratio, live weight, haemoglobin and pack cell volume values of chickens. Dry matter digestibility, metabolizable energy and nitrogen retention not influenced by dietary lysine to energy ratio. Also, white blood cell, red blood cell, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration in female Venda chickens aged 91 days were not influenced by dietary lysine to energy ratio. It is concluded that dietary lysine to energy ratios of 0.672, 0.646, 0.639 and 0.649 optimized feed intake, growth rate, FCR and live weight in indigenous female Venda chickens fed diets containing 8 g of lysine/kg DM, 150 g of CP/kg DM and 11 MJ of ME/kg DM. This has implications in diet formulation for indigenous female Venda chickens.     

Effects of dietary copper supplementation on production performance and plasma biochemical parameters in broiler chickens

1. A study was conducted to estimate the effect of copper (Cu) supplementation on growth performance and biochemical profiles of blood and meat in broiler chickens.

2. A total of 240?d-old broiler chicks (Vencobb-100) were randomly divided into 12 groups, each of 20 chicks (4 treatments?×?3 replicates).

3. The basal diet (T₁) contained 215?g?kg^?1 crude protein (CP), 12·76?MJ?kg^?1 ME, 32?g?kg^?1 total calcium and 5?g?kg^?1 total phosphorus. T_2, T₃ and T₄ were formulated to contain an additional 75, 150 and 250?mg?Cu?kg^?1 diet, respectively. Copper sulphate pentahydrate (CuSO₄, 5H₂O) was used as the source of Cu.

4. Significant reductions in plasma total cholesterol and triglyceride, and an elevated concentration of HDL-cholesterol, were observed in the chickens fed with 250?mg?Cu?kg^?1 (T₄) of feed at the 3rd and 6th week of the experiment. Total cholesterol in meat decreased significantly in the birds fed with dietary Cu at 250?mg?kg^?1 (T₄) of feed.

5. Growth performance was measured in terms of live weight gain, cumulative feed intake and feed conversion ratio at the end of d 21 and d 42 of the experiment, and the result was found to be commercially beneficial for the chickens receiving 150?mg?Cu?kg^?1 (T₃) of diet. The concentration of Cu in breast muscle and liver increased significantly at the end of experiment.

6. From this study it can be concluded that supplementation with dietary Cu may be beneficial for production performance and plasma biochemical characteristics of broiler chickens.     

The effect of live weight gain and live weight loss on body composition of Merino wethers: dissected muscle, fat, and bone.

Sheep were slaughtered after live weight gain (LWG) and live weight loss (LWL) to evaluate the effect of different periods of normal and retarded growth on dissected carcass components. Thirty-five Merino wether sheep were allowed ad libitum access to the experimental diet of 80% alfalfa chaff and 20% cereal grain (17.23% CP and 18.10 MJ/kg of GE) to grow from 23.0 to 33.0 kg live weight and then fed to lose 10 kg at 133 g/d. Five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6, 26.3, and 23.0 kg during LWL. Fleece-free empty BW was similar in both LWG and LWL animals at all common slaughter weights because of the lesser and greater weights of the alimentary tract contents and the fleece, respectively, in the LWL animals. Carcass weight or dissected side weight was greater in LWL animals at each common slaughter weight but significantly so (P less than .05) at the 23.0 kg live weight only. Total side muscle weight was similar in LWG and LWL animals at each common slaughter weight, but the proportion of muscle in the dissected side weight was lower (P less than .05) in LWL animals at 23.0 kg live weight. Total side fat, subcutaneous fat, intermuscular fat, and kidney and channel fat weights were all greater in LWL animals at each common slaughter weight, but significantly so (P less than .05) at the 23.0 kg live weight only. Total side bone weight was higher at both 26.3 kg (P less than .01) and 23.0 kg (P less than .05) in the LWL animals. Weight loss in young sheep mobilized more weight of muscle than fat from the carcass, whereas bone weight was constant.     

Effects of different formulations of α-tocopherol acetate (vitamin E) on growth performance,meat quality and antioxidant capacity in broiler chickens

1. The objective of this study was to investigate and compare the effects of α-tocopherol acetate (vitamin E (VE)) and microencapsulated VE (MVE) on growth performance, meat quality and antioxidant capacity in broiler chickens.

2. A total of 360 d-old broiler chicks were procured and randomly allocated into three groups with 6 replicates. Each replicate had 20 chickens. Chickens were fed with basal diets (CON group) or experimental diets supplemented with 20 mg/kg VE (VE group) or 20 mg/kg MVE (MVE group) for 42 d.

3. The results showed that the MVE group had higher body weight gain (BWG) than the CON and VE groups, and higher gain/feed ratio (G/F ratio) than the CON group during the period of 22–42 d. During the whole experiment, a higher increase in BWG was found in the MVE group than the CON group.

4. Chickens fed on diets supplemented with the VE or MVE had lower abdominal fat percentage, higher pH and antioxidant enzyme activity than the CON group in the breast meat.

5. There was an increased tendency in the hepatic glutathione peroxidase (GSH-Px) enzyme activity of the VE and MVE groups than the CON group. The hepatic mitochondrial total antioxidant capacity and GSH-Px enzyme activity in the MVE group were higher than the CON group. Hepatic 2,2-dipheny-?-picrylhydrazyl scavenging activity of the MVE group was higher than the CON group.

6. These results suggested that the dietary addition of VE or MVE could improve breast meat quality in broilers. MVE supplementation may improve growth performance, hepatic mitochondrial antioxidant capacity and free radical scavenging capacity in chickens. In addition, dietary supplementation of MVE gave better broiler growth performance than VE.

     

椰子粕对文昌鸡生长性能、屠宰性能和肉品质的影响

本试验旨在研究不同水平椰子粕对文昌鸡生长性能、屠宰性能和肉品质的影响。选取480只80日龄健康状态良好的文昌鸡，随机分为4组，每组6个重复，每个重复20只鸡。对照组饲喂基础饲粮，3个试验组分别在基础饲粮中添加1.50%、4.50%和7.50%椰子粕。试验期为40 d。结果显示：1）与对照组相比，1.50%和7.50%组料重比均显著下降（P<0.05）；各组间末重、平均日增重和平均日采食量均无显著差异（P>0.05）。2）与对照组相比，1.50%组屠宰率显著提高（P<0.05），而其他试验组屠宰性能均无显著差异（P>0.05）。3）与对照组相比，4.50%组胸肌pH24 h显著降低（P<0.05），各试验组pH45 min、24 h滴水损失、熟肉率、剪切力和腿肌pH24 h均无显著差异（P>0.05）。4）与对照组相比，各试验组肌肉肌纤维直径和平均横截面积都无显著差异（P>0.05）。5）与对照组相比，1.50%和7.50%组胸肌中粗蛋白质含量显著提高（P<0.05），但各试验组肌肉中水分、肌内脂肪和腿肌粗蛋白质含量无显著差异（P>0...