Kaempferol improves carcase characteristics in broiler chickens by regulating ANGPTL3 gene expression

1. The objective of this study was to examine the beneficial effects of kaempferol, a naturally occurring polyphenol, on carcase characteristics in broiler chickens and the mechanisms involved in this regulation.

2. Broiler chickens were randomly divided into 7 groups: control, carrier control, kaempferol (0·3%), kaempferol (0·6%), hypercholesterolemic (HLD), HLD and kaempferol (0·3%), HLD and kaempferol (0·6%).

3. Seven weeks after treatment, carcase characteristics, lipid levels in the blood and liver, expression of hepatic Angiopoietin-like protein 3 (ANGPTL3) mRNA, and expression of adipose lipoprotein lipase (LPL) protein were determined.

4. Treatment with kaempferol (0·3 or 0·6%) significantly increased plasma high-density lipoprotein cholesterol levels, decreased percentage of abdominal fat, thickness of subcutaneous fat, plasma and hepatic total cholesterol and triglyceride concentrations, muscle malondialdehyde level and down-regulated expression of ANGPTL3 mRNA concomitantly with up-regulated expression of LPL protein in normal and hypercholesterolemic broiler chickens.

5. Kaempferol (0·3 or 0·6%) treatment had no significant effect on the values of percentage of breast muscle, percentage of leg muscle, carcase weight and eviscerated percentage.

6. The results suggest that kaempferol improves carcase characteristics by decreasing expression of ANGPTL3 in broiler chickens.     

Fat deposition and heat production as responses to surplus dietary energy in fowls given a wide range of metabolisable energy: Protein ratios

1. Female broiler fowl between 21 and 42 d of age were given diets with apparent metabolisable energy (AME) contents ranging from 8 to 15 MJ/kg at each of two crude protein (nitrogen x 6.25; CP) contents (130 and 210 g/kg).

2. Food intake was measured daily for 21 d. Body composition was determined at 42 d and gains in body mass, protein, fat and gross energy calculated by comparison with a group analysed at 21 d. Heat production was calculated by difference between AME intake and energy gain.

3. Decrease of food mass intake with increased dietary AME concentration limited the increase in AME intake to about 25%, despite the near 2‐fold range of AME concentrations.

4. There was no effect of CP concentration on food mass intake. CP intake was directly related to CP: AME ratio.

5. When body weight differences were taken into account, heat production was independent of dietary AME concentration, but increased by about 8% on the higher‐protein diets.

6. There were strong linear correlations between dietary CP:AME ratio and carcase protein: energy ratio, carcase fat content and carcase protein content.

7. It was concluded that the growing fowl responded to dietary nutrient: energy ratio, and the associated differences in nutrient and energy intakes, by varying the rate of energy deposition as fat, without regulatory variation of energy dissipation as heat.     

Influence of various dietary protein levels on carcase composition in the male Japanese quail (Coturnix coturnix japonica)

1. The present study was conducted to determine the effect of various dietary protein concentrations on the carcase composition of male Japanese quail.

2. Six diets varying in protein from 160 to 300 g/kg and containing approximately 11–72 MJ/kg ME were fed for 5 weeks and analysed for dry matter, protein, fat and ash.

3. Treatments affected carcase weight, dry matter, protein, ether extract and ash

4. The water content of the carcases decreased with increasing dietary protein concentrations, while the carcase protein content increased with higher dietary protein. The carcases with the highest fat content were obtained from quail receiving the low protein diet.     

Urea and aspartic acid supplementation of low‐protein broiler diets1

1. L‐Aspartic acid does not seem useful as a protein surrogate in conventionally formulated low‐protein diets for broiler chicks.

2. Urea as a protein substitute does not enhance the value of conventional broiler diets.

3. Urea does not improve broiler diets that have been supplemented with fish meal or crystalline amino acids to satisfy requirements for all indispensable amino acids.

4. Urea is absorbed into the bloodstream, but is not assimilated into body proteins.     

Influence of heated vegetable oils and α‐tocopheryl acetate supplementation on α‐tocopherol,fatty acids and lipid peroxidation in chicken muscle

1. Chicks were fed on diets containing fresh, heated or α‐tocopheryl acetate‐supplemented heated vegetable oils. The effects on α‐tocopherol status, and on the fatty acid composition and oxidative stability of thigh and breast muscle were determined.

2. Plasma α‐tocopherol was significantly correlated with α‐tocopherol concentrations in thigh and breast muscle.

3. The fatty acid profiles of muscle lipids reflected dietary fatty acid composition.

4. The consumption of heated sunflower and linseed oils reduced α‐tocopherol status, altered fatty acid composition of muscle lipids and increased susceptibility of muscle to lipid oxidation.

5. Supplementation of diets containing heated oils with α‐tocopheryl acetate resulted in some alleviation of these effects.

6. The results indicate that caution should be exercised in the use of thermally oxidised oils in poultry diets if undesirable changes in composition and oxidative stability of carcase lipids are to be avoided.     

Effects of a beta‐adrenergic agonist clenbuterol) on performance,carcase composition,hepatic microsomal mixed function oxidase and antibody production in female broilers treated with or without corticosterone

1. Beta‐adrenergic agonist (Clenbuterol, 0.33 mg/kg) and corticosterone (10 mg/kg) were incorporated into a diet based on maize and soyabean meal. Their effects on performance, carcase composition, hepatic microsomal mixed function oxidase and antibody production were investigated in female broilers.

2. Dietary corticosterone reduced the titre to sheep red blood cells, while it was unchanged by clenbuterol.

3. Clenbuterol exerted a promoting effect on gain‐to‐food ratio, carcase protein and hepatic microsomal cytochrome P‐450 content.

4. Addition of clenbuterol to the corticosterone‐containing diet prevented the increase in abdominal fat weight and uric acid excretion induced by corticosterone, but did not affect total fat mass.

5. The results showed that clenbuterol reduced abdominal rather than carcase fat and prevented protein degradation in the body when chicks were treated with corticosterone. Clenbuterol also influenced the content of cytochrome P‐450, but not the humoral immunity.     

Yield and composition of raw and cooked meat of small white turkeys as influenced by dietary nutrient density and energy to protein ratio

1. Raw and cooked meat yields and the dry matter and fat contents of meat samples were determined on 144 carcases of Small White turkeys fed on diets that varied in nutrient density (ND) and energy to protein ratio (E:P).

2. High ND diets increased body weights, eviscerated carcase weights, relative carcase yields and carcase skin yield, but not breast or total meat yields.

3. Feeding a low ND diet to 6 weeks followed by diets with progressively increasing ND yielded performance and carcases with qualities comparable to feeding diets of constant medium or high ND; consequently cost savings could be made.

4. Increasing E:Ps reduced body weights, eviscerated carcase weights and carcase yields. Breast and total meat yields from male but not female carcases, and skin yield of female but not male carcases decreased with higher E:Ps.

5. The fat contents of breast and thigh meat samples increased with ND. The fat content of breast but not thigh meat decreased with higher E:P. Dry matter contents of meat samples did not vary consistently with changes in fat content.     

Effects of dietary corticosterone and trilostane on growth and skeletal muscle protein turnover in broiler cockerels

1. The effects of dietary corticosterone and trilostane, an inhibitor of glucocorticoid synthesis, on: growth, rates of synthesis and breakdown of skeletal muscle protein, and content of abdominal fat were studied in broiler chickens.

2. Dietary corticosterone (5, 10 or 20 mg/kg) depressed body weight gain and increased abdominal fat content in a dose‐dependent manner while dietary trilostane (1.4 or 7.0 mg/kg) had no effect.

3. The rate of protein breakdown in skeletal muscle estimated from N‐methylhistidine excretion was increased in a dose‐dependent manner by dietary corticosterone but it was decreased by trilostane.

4. The rate of skeletal muscle protein synthesis was not affected by corticosterone although it was decreased by trilostane.

5. Plasma corticosterone concentration was increased in a dose‐dependent manner by dietary corticosterone and decreased by treatment with 7 mg trilostane/kg diet.

6. The results indicate that higher concentrations of plasma corticosterone increase protein breakdown in skeletal muscle but do not affect muscle protein synthesis while both the rates of synthesis and breakdown are decreased when plasma corticosterone concentration is reduced.     

Food intake and growth in chickens given food in the wet form with and without access to drinking water

1. Individually caged growing chickens were offered a commercial grower food mixed with 1–5 to 2^‐25 times the weight of water and the effects, compared to giving the same food in air‐dry form, on food intake, body weight gain and carcase composition were investigated.

2. Male broilers (24) were given either a grower food in the air‐dry form with access to drinking water or the same food mixed with 2–0 parts of water (700 g water/kg of mixed food) with no drinking water from 28 to 49 d of age. From 49 to 63 d all birds were given dry food and drinking water and were then killed for carcase analysis. Food intake and weight gain were significantly increased during the wet‐feeding period, as was carcase protein but not abdominal or carcase fat at the end of the experiment.

3. Five male broilers were given each of 5 dietary treatments containing 0 (control), 1.5, 1.75, 2.0 and 2.25 times added water (640, 673, 700 and 723 g water/kg) from 28 to 49 d. Food intakes, body weight gains and carcase weights were significantly increased for all water additions compared with dry food, but there were no significant differences between different water additions.

4. Female broiler chicks responded to wet feeding (700 g water/kg) in a similar manner to males and the dry matter approximate digestibility was increased from 0.65 for the dry food to 0.73 for the wet.

5. Cockerels of an egg‐laying strain did not increase their intake of dietary dry matter when it was fed in the wet form (700 g water/kg), but there was a significant increase in body weight gain.

6. Male broilers were offered wet food (700 g water/kg) with or without access to drinking water. There was equal stimulation of food intake, growth and carcase weight with both wet‐feeding treatments.

7. Providing food mixed with sufficient water to give a porridge‐like consistency significantly increased weight gains in each of the five experiments and significantly improved food conversion efficiency in three of the five. It is not necessary to withold drinking water in order to obtain this effect.     

Effect of choice feeding on the performance of broilers

1. Male broilers from 21 to 56 d of age were fed their diet either mixed as pellets or mash, or as separate ingredients presented on a free‐choice basis, to determine whether feeding method affected growth, carcase composition or profitability to 56 d of age.

2. The 12 treatments were: 2 completely balanced diets fed as mash or pellets, 8 choice fed diets containing maize or sorghum as the energy source (whole or mash) and protein concentrate (pellets or mash) and 2 unbalanced mixed mash diets containing 50% grain (maize or sorghum) plus 50% protein concentrate.

3. For the choice treatments, one food, grain (maize or sorghum) or protein concentrate (mash or pellets), was placed in each feeder. Broilers fed the complete pelleted or mash diet received the diet in both feeders. Food consumption was recorded weekly. Broilers were weighed at 42 and 56 d of age.

4. There were no significant differences between treatments and the pelleted control diet with regard to body weight, food consumed, food efficiency, carcase ash, dressing percentage and mortality.

5. Choice fed broilers receiving the energy source as whole grains had larger gizzards while the higher protein diets (50/50) resulted in a higher carcase moisture and protein but lower carcase fat than the broilers fed the pelleted control diet.

6. The main advantage of choice feeding appears to be the economical savings of feeding whole grains as the energy source.     

Economic effects of increased vitamin E supplementation of broiler diets on commercial broiler production

1. The economic effects of increased vitamin E supplementation in 168 commercial broiler flocks incorporating over 3 million birds was assessed using a computerised data retrieval system.

2. Approximately half of the flocks were fed on either a high (163 mg/kg) vitamin E or on a normal (44 mg/kg) vitamin E‐containing diet throughout production.

3. Approximately half of the flocks were the progeny of breeder flocks which had been fed on a high vitamin E‐containing diet throughout production.

4. The improvement in target income in the vitamin E‐supplemented broiler flocks was 8–44% (P < 0.01).

5. The residual improvement in target income in these flocks, after the cost of the additional vitamin E was taken into account, was 2.74% and failed to reach statistical significance.

6. The increased net income was achieved by a significantly improved food conversion ratio and average weight per bird (P < 0.05).

7. There was no overall effect of vitamin E supplementation of broiler breeders on subsequent broiler performance.     

The occurrence of giant fibres in different muscles of two chicken genotypes

1. The occurrence of Giant Fibres (GF) in three muscles (Pectoralis major (PM), Iliotibialis lateralis and Semimembranosus) with different types of energy metabolism was studied in slow- and fast-growing chicken strains.

2. A total of 20 one-day-old Leghorn chicks (slow-growing) and 20 broiler (Ross 508) chicks (fast-growing) were reared to 100 and 45 d, respectively.

3. A small percentage of GF was seen in pre rigor muscle samples even at 3 min post mortem in both genotypes and in all muscle types studied.

4. From 3 min to 24 h post mortem GF increased both in Leghorn and broiler chickens but to a different extent according to muscle type and genotype.

5. The highest GF 24 h post mortem value was found in the PM muscles belonging to the fast-growing broiler line.

6. It was concluded that every type of muscle can develop GF, but this phenomenon is more evident in the PM especially in animals selected for increased growth rate.     

Crossbreeding effects for body weight and carcase traits in Pekin duck

1. Three sire lines of Pekin duck, three dam lines and 9 crosses between these two groups were tested in replicated tests from 1987 to 1991. Body weight at the age of 7 weeks (n = 5189), carcase percentage, percentage of abdominal fat and thickness of breast muscles were recorded (n = 1432 for carcase traits).

2. The data were analysed by linear models. All models contained the factors test and sex. When analysing only crosses, general and specific combining abilities (GCA and SCA respectively) were included as well as their interactions with the test. Using the complete data set (lines and crosses), direct genetic and heterotic effects were considered.

3. The factors test and sex were significant in both data sets for all traits.

4. For body weight, all genetic factors were significant. The average heterosis was 65 g ± 9 g (2.2%); the highest observed heterosis was 7.7%.

5. For carcase percentage, the heterosis was always negative (up to — 2.1%), whereas in abdominal fat, a desirable negative heterosis was observed only in one cross. No significant heterotic or combining ability effects were observed in the thickness of breast muscles.

6. Significant interactions between at least one genetic factor and test were found in all traits.

7. The relative importance of GCA and SCA, possible sources of confounding estimates of genetic effects, the importance of heterotic effects and genotype × environment interactions are discussed.     

Welfare of broiler breeder and layer females subjected to food and water control during rearing: Quantifying the degree of restriction

1. A factorial experiment was conducted with females of two broiler breeder and one layer strains. The birds were fed ad libitum or restricted and were provided with free or limited access to water to simulate commercial rearing practices.

2. There was little difference between the broiler breeder strains except in body weight at 16 and 18 weeks of age.

3. Food intake relative to body weight was higher in the broiler breeders compared with the layer strain.

3. The degree of restriction was defined as the food intake of re‐stricted birds as a proportion of the estimated intake of birds of the same body weight fed ad libitum. The value declined from 0.60 to 0.45 during the rearing period.

5. In the ad libitum treatments broiler breeders drank more than layers, whereas when restricted, layers drank more than broiler breeders.

6. Water intake was 2.50 times higher in restricted compared with ad libitum‐fed layers and 1.25 times higher in restricted than ad libitum‐fed broiler breeders, with free access to water.     

Effect of environmental temperature,dietary energy,age and sex on broiler carcase portions and palatability

1. Two environmentally‐controlled houses, one at a constant 21°C (low temperature), the other diurnally cycling at 21 to 30°C (high temperature) and two diets of 13.0 MJ ME/kg (low energy, LE) and 13.8 MJ ME/kg (high energy, HE) were used to study the effects of age and sex on broiler carcase portions, dissected tissue proportions, and meat quality.

2. Slaughtering at 54 d instead of 34 d produced broilers with breast and leg weights of 277 and 308 instead of 284 and 319 g/kg carcase respectively, and a higher cutting loss (31 versus 6 g/kg carcass).

3. Males had lower proportions of breast, breast meat and fat, but higher proportions of leg, leg bone, and total meat to fat ratio than females.

4. Cycling high temperature resulted in higher breast, and lower leg proportions than constant low temperature.

5. High dietary energy content increased cutting loss, proportion of breast fat and lowered meat to fat ratio when compared to low energy, but did not affect the flavour of the meat, which was improved by age and high environmental temperature.     

Effects of dietary protein content,addition of nonessential amino acids and dietary methionine to cysteine balance on responses to dietary sulphur‐containing amino acids in broilers

1. Two experiments were conducted with male broiler chicks from 2 to 5 weeks of age to determine the effect of dietary protein content and amino acid balance on the response to dietary sulphur‐containing amino acids (SAA) in terms of performance and carcase quality.

2. In experiment 1, 5 graded amounts of a DL‐methionine and L‐cysteine (1:1 by weight) mixture were added to basal diets containing 197 or 233 g crude protein/kg. The diets containing 197 g protein/kg were fed with or without the further addition of 36 g crude protein/kg from nonessential amino acids. The amino acid balance of all diets was kept constant for all essential amino acids except the SAA. In experiment 2, 5 graded amounts of SAA from either a crystalline source (DL‐methionine or a mixture of DL‐methionine and L‐cysteine) or from intact proteins were added to a diet containing 208 g protein/kg.

3. At each protein concentration there were significant responses to the SAA addition in weight gain, food conversion efficiency, and carcase quality. Non‐linear exponential regression analyses were used to describe bird responses to SAA concentration. The broiler chick's requirement for SAA increased with increasing dietary protein concentrations ranging from 197 to 259 g protein/kg.

4. The utilisation of SAA differed also with differences in origin (crystalline or peptide‐bound), and methionine:cysteine balances. Compared to DL‐methionine, a 1:1 mixture of DL‐methionine and L‐cysteine was only 81% or 86% as effective in supporting growth or food conversion, respectively. SAA from added protein was even less effectively utilised.

5. The addition of nonessential amino acids tended to decrease food intake without affecting SAA utilisation.

6. Slaughter yield and breast meat yield were clearly increased while fat deposition was clearly decreased, by SAA addition. The response in breast meat yield suggested an important economic benefit for further meat processing. Nitrogen retention was significantly enhanced by SAA supplementation from crystalline sources, and this led to reductions of up to 30% in the amount of nitrogen excreted per kg weight gain.     

Value of peanut skins as a dietary ingredient for broiler chickens

1. Diets containing different concentrations of peanut skins (0, 50, 100, 150 and 200 g/kg) were fed ad libitum to 5 groups of 1‐d‐old broiler chicks (Cobb 100 strain) for a period of 7 weeks. Birds had free access to water.

2. The concentration of peanut skins in the diet had no effect on food consumption.

3. Overall significant correlations were found between the concentrations of peanut skins in the diet and weight gain (r= –0.52), food:‐gain ratio (r=0.96) and carcase dressing percentage (r= –0.94).

4. There were no deaths attributable to concentration of peanut skins in the diet.     

Influence of food intake and sex on the growth and carcase composition of Pekin ducks

1. The effects of food intake on growth and carcase composition of male and female meat‐type Pekin ducks were investigated between 14 and 56 d of age and between 0.416 kg (14 d) and 2.5 kg live body weight.

2. Males grew faster between 14 and 56 d of age and contained less fat and more protein and water in the eviscerated carcase at 56 d than females.

3. For both sexes, food : gain ratio deteriorated as food intake increased from 0.49 ad libitum intake to ad libitum intake. Growth rate, carcase weight and carcase fat content increased linearly with increase in food intake. Carcase fat content at 56 d was more sensitive to change in the amount of food consumed than either growth rate or carcase weight.

4. Between 0.42 kg (14 d) and 2.50 kg live body weight, growth rate and food :gain ratio improved as food intake was increased from 0.61 ad libitum to ad libitum. Males grew faster and produced leaner carcases than females.

5. Carcase fat content at 2.50 kg live body weight (1.60 kg carcase) increased in a curvilinear fashion with increase in food intake, and the magnitude of the response was lower for females than for males. A similar interaction existed between the effects of sex and the amount of food consumed for the proportions of protein and water in the eviscerated carcase at 2.50 kg live body weight.     

Correlations between body measurements and tissue composition of oat-fattened White Kołuda geese at 17 weeks of age

1.?The aim of the present study was to evaluate the yield and tissue composition of carcases from White Ko?uda® ganders (males) and geese (females), and to determine the relationships between body measurements and carcase tissue composition.

2.?The experiment was carried out on 200 geese (100 males and 100 females) reared to 14 weeks of age and then fed with oats for the next 3 weeks. Live body weight and body dimensions, slaughter yield, weight and percentage of muscles and skin with fat in carcase were measured and correlation coefficients were calculated between body measurements and slaughter values and carcase tissue composition.

3.?White Ko?uda® geese reared to 17 weeks of age were characterised by high body weight (6705 g) and good muscle yield (29·9%). Males had greater body weight, musculature and fatness than females. Sternum length and breast circumference, width and depth were good indicators of carcase muscle weight in 17-week-old geese.

4.?Negative coefficients of correlation between sternum length and weight of skin with subcutaneous fat indicate that increased selection pressure in pedigree flocks of geese on sternum length should be paralleled by reduced carcase fatness in these birds.     

Broken bones in chickens: Effect of stunning and processing in broilers

1. Broilers and broiler carcases, sampled immediately before the stunner, at the end of the processing line and from a supermarket company, were physically dissected to determine the incidence of broken bones.

2. Over 95% of the frozen broilers from the supermarket company had broken bones and there were between 3 and 4 breaks per carcase. Only 3% of live birds had broken bones so most of the carcase damage must have been caused by processing.

3. The effect of 100, 200 and 300 V electrical stunning on the incidence of broken bones was investigated: increasing voltage resulted in an increase in the incidence of broken bones in the collar region.