Effects of method of processing and chilling of Turkey carcasses on processing losses,water absorption and yields

1. The effects of wet or dry plucking, wet or dry evisceration procedures and method of chilling on processing losses and water uptake during chilling were studied using 19‐week‐old female large white turkeys.

2. Dry plucking increased weight loss due to plucking and eviscerating, and reduced chilled carcass yield.

3. Dry eviscerating increased carcass water uptake during chilling.

4. Pre‐chilling with running water increased carcass water uptake compared with chilling in ice and water alone.

5. Water uptake during chilling appeared to be increased by longer eviscerating time.     

Biochemical,physiological and production indices related to fat metabolism in the laying fowl at various stages of physiological development

1. The significance of fat accumulation during physiological development of layers was studied using White Leghorn x Australorp pullets from 12 weeks of age.

2. Liver fat, carcass fat, liver weight and body weight increased markedly at the onset of sexual maturity.

3. Within the liver, the protein to DNA ratio did not alter significantly during development; glycogen was not consistently depleted by egg production.

4. Liver fat content was significantly correlated with carcass fat, liver weight and DNA concentration, and plasma total lipid and cholesterol, independent of stage of development; with body weight, liver protein, moisture, and protein to DNA ratio, excluding the period prior to commencement of sexual maturation; and with plasma phospholipid during lay.

5. Obesity was a feature of faster growing fowls which matured earlier, consumed more, utilised food less efficiently for egg production and produced fewer saleable eggs.     

Composition and amino acid content of carcass,skin and feathers of the growing gosling

1. Growth rate, food intake and utilisation were determined for goslings (Anser cireneus) from hatching to 7 weeks of age.

2. The relative weight of the carcass (body without feathers, skin or intestinal content) decreased from 0.83 of total body weight at hatching to 0.73 at 7 weeks. The skin relative weight increased from 0.12 at hatching to 0.17 at 2 weeks of age and subsequently remained constant. The weight of feathers increased from 0.034 of body weight at hatching to 0.08 at 7 weeks.

3. The fat of the carcass and skin increased during the 7‐week experimental period. The skin retained about half of the total body fat.

4. While amino acid compositions of feathers and skin proteins were quite similar to data reported for other birds, carcass proteins were lower in methionine and lysine.     

Feeding standards during lay and reproductive performance of broiler breeders

1. Broiler parent stock (Marshall) were supplied with energy and protein from diets in amounts defined as percentages of an allowance such that nutrient intake increased or decreased in three consecutive periods from 23 to 63 weeks of age.

2. A 20% reduction in energy allowance from 23 to 34 weeks was associated with reduced body‐weight gain, egg weight and carcass constituents except ash, but had no significant effect on egg production or hatchability.

3. Increases in nutrient intake after 34 weeks were associated with an increase in body‐weight gain and carcass fat.

4. Moderate decreases in energy intake after 34 weeks were associated with reduced body‐weight gain, and a 15% reduction in nutrient intake resulted in a decrease in body weight and egg weight.

5. It is suggested that a feeding allowance which controls body‐weight gain during early lay, and then allows for a gradual increase in body weight over the breeding period may be the most efficient way of feeding the broiler breeder hen.     

Effects of food intake regulation on the energy metabolism of laying hens

1. The effects of dietary energy restriction on the energy metabolism of post‐peak‐of‐lay hens of two hybrid layer strains were studied by indirect calorimetry.

2. Starving and resting rates of heat production (SHP and RHP) were measured, over 1‐d periods, at intervals during a 25‐week period in which the experimental birds were individually restricted to 80% of their previous energy intake ad libitum.

3. In both strains mean RHP per bird was about 7% lower in the restricted birds than in controls fed ad libitum, but when RHP was expressed in terms of metabolic body size (kg^0.75) the two groups did not differ.

4. Mean SHP per bird was about 18% lower in the restricted birds of both strains than in the corresponding controls; the decrease in SHP per kg^0.75 was 12%.

5. Heat increment of feeding and calculated maintenance energy were higher, and net availability of metabolisable energy for maintenance and production was lower, in the restricted than in the control groups.

6. Gross efficiencies of egg production, in terms of both mass and energy, increased in the restricted birds.

7. Live‐weight and total carcass energy after 25 weeks of restriction were respectively about 15% and 30% lower in the restricted groups of both strains than in the groups fed ad libitum.     

Selection for food conversion in broilers: Body composition of birds selected for increased body‐weight gain,food consumption and food conversion ratio

1. Body composition was determined in 9‐week‐old chickens sampled from four lines selected either for increased body‐weight gain (line W), for increased food consumption (line F), for decreased food conversion ratio (line E), or at random (line C), after three, four and five generations of selection.

2. After five generations of selection the proportions of carcass water (678 g/kg) and protein (187 g/kg) were highest in line E and lowest (636, 180 g/kg respectively) in line F. The proportion of fat was lowest (83 g/kg) in line E and highest (134 g/kg) in line F.

3. Lines W and C were similar and intermediate to lines E and F for all the carcass constituents.

4. There was more fat in females (115 vs 98 g/kg) and less protein (177 vs 190 g/kg) and water (652 vs 665 g/kg) than in males.

5. Line differences in carcass composition were not appreciably altered if birds were killed at equal weight rather than equal age.     

Genetic evaluation of carcass traits in Japanese quail using ultrasonic and morphological measurements

1. A study was conducted to evaluate the carcass composition of 1083 live birds using ultrasonic and morphological measurements and to estimate the genetic relationship between predicted and dissected carcass composition in Japanese quail.

2. Birds were reared for 35 d, and morphological measurements consisting of the length and width of breast muscle were recorded for all birds using a digital caliper. After slaughtering, the weight and percentage of carcass traits were measured on chilled carcasses. The dimensions of breast muscle were measured in 638 birds with an ultrasound scanner before slaughter at 35 d of age.

3. Genetic parameters from univariate and bivariate analyses were obtained by restricted maximum likelihood using ASREML software.

4. Genetic correlations between body weight at 35 d (BW35) and the percentage of carcass traits were low. Therefore, selection for BW35 may not effectively improve the yield of carcass components in Japanese quail.

5. High genetic correlations between carcass traits and ultrasonic measurements compared to morphological measurements suggest that the ultrasonic technique is a better method to improve breast weight and yield in Japanese quail.     

Effect of food and water deprivation on live‐weight shrinkage,eviscerated carcass yield and water absorption during chilling of Turkey carcasses

1. The effect of depriving turkeys of food or both food and water for 12 or 24 h prior to slaughter on live‐weight shrinkage, eviscerated carcass yield and water uptake by the carcass during chilling was studied.

2. Deprivation of both food and water more than doubled the live‐weight shrinkage caused by removal of food alone, and deprivation for 24 h doubled the live‐weight shrinkage caused by 12 h.

3. Reduction in eviscerated carcass yield was small (4 g/kg) when only food was removed for 12 h but was increased by deprivation of both food and water or by depriving for 24 h.

4. Carcass weight gain during chilling in ice and water was not influenced by pre‐slaughter treatment.     

Effects of short intermittent lighting on food consumption and performance of dwarf broiler breeders and progeny

1. Two hundred and sixty four dwarf broiler breeder hens were subjected to ad libitum or restricted feeding and to four lighting patterns: 15L (bright light):9D (dark), 15L:9d (dim light), 2L:10d: 1L:11d, (0.5L:3.5d) × 6.

2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.

3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.

4. Persistency of egg production was impaired by intermittent lighting.

5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.

6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).

7. Egg and chick weights were higher in hens fed ad libitum.

8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.

9. The best performance was obtained in restricted hens on the conventional lighting pattern.     

Effect of lighting treatment on the productivity,health, behaviour and sexual maturity of heavy male Turkeys

1. Turkey poults (1620) were used to compare the effects of three lighting programmes on heavy strain males reared to 188 d: constant light (24L:0D, CON); increasing light (6L:18D at 7 d gradually increasing to 20L:4D by 63 d, INC); a pattern identical to INC followed by a decrease in daylength from 84 d to 10L:14D at 112 d (DID).

2. Lighting affected growth pattern but had no effect on body weight at 118 d or overall food to gain ratio.

3. Both INC and DID lighting reduced overall mortality in comparison to CON light primarily because of a reduction in the incidence of skeletal disease and spontaneous cardiomyopathy. INC and DID lighting increased the incidence of cannibalism.

4. Turkeys given INC or DID lighting had a superior ability to walk in comparison to those birds given CON light.

5. INC and DID males stood, ate and drank more frequently, and sat less often than CON turkeys during behavioural observation.

6. There were no lighting effects on carcase composition except that INC and DID birds had heavier keel bones. The ultimate force per cm² (stress) required to break femora was greater for turkeys given INC and DID lighting (P = 0.065).

7. Plasma testosterone concentrations at 117 d were 272.5, 115.2 and 29.5 pg/ml for turkeys given CON, INC and DID lighting, respectively (P= 0.072). Testosterone concentration was not related to growth rate.     

The effect of production system (barn and free-range), slaughtering age and gender on carcass traits and meat quality of partridges (Alectoris chukar)

1. A total of 400 Alectoris chukar partridges were reared in either barn or free-range production systems and slaughtered at 14, 16 or 18 weeks of age in order to determine the effects of production system, age and gender on carcass traits (live weight, carcass weight, carcass yield, carcass part and edible inner organ percentages at slaughtering) and meat quality (L*, a* and b* meat colour and pH).

2. Production system had a significant effect on both slaughter traits and meat quality.

3. Partridges raised in barn conditions had higher live weights and carcass weights whereas meat quality was better in birds raised in the free-range system.     

Relationship between body fatness,ovarian structure and reproduction in mature females from lines of genetically lean or fat broilers given different food allowances

1. Reproductive and other characteristics were measured at 34 and 60 weeks of age in broiler breeder hens on 6 different feeding regimes. The hens came from genetically lean and fat lines selected on the basis of low or high 7‐week plasma very low density lipoprotein (VLDL) concentration.

2. Plasma VLDL concentrations were consistently higher at all ages in fat line hens but were not affected by dietary treatment.

3. Mature body weight did not differ between the lines in birds fed ad libitum but with food restriction throughout life, fat line birds were lighter at 34 weeks.

4. There was little difference between the lines in abdominal fatness of birds fed ad libitum up to 60 weeks. Fat line birds were always fatter than lean line counterparts under food restriction.

5. Egg production was higher in lean line birds fed ad libitum but food restriction improved egg production in both lines. Peak egg productions were similar in both lines but there was evidence that the optimal food allowances for egg production was higher in the lean compared with the fat line.

6. Ovarian yellow follicle numbers were highest at 34 weeks in ad libitum fed lean line birds and declined linearly with decreasing body weight caused by food restriction but there was no such relationship in fat line birds.

7. White follicle numbers were higher and follicular atresia was lower in the lean line.

8. It is concluded that poor reproduction in fat line birds was associated with inhibition of follicular development and atresia rather than by high plasma VLDL concentrations promoting excessive yolk formation.     

The effects of trienbolone acetate on carcass composition,conformation and skeletal growth of Turkeys

1. The carcasses of 66‐ and 73‐d‐old stag turkeys implanted with 20 mg trienbolone acetate (TA) at 49 d of age were analysed and the results compared with those of untreated controls.

2. Treatment with TA improved growth, increased carcass moisture and tended to decrease carcass fat and ash; protein content was not altered by implantation.

3. Treatment with TA produced a marked improvement in efficiency of conversion of dietary protein to carcass protein.

4. Carcass formation of 70‐ and 77‐d‐old turkeys of both sexes implanted with 20 mg TA at 49 d of age was not markedly different from that of controls in terms of the relative proportions of the major body components nor in relative skeletal proportions.

5. Implantation with TA reduced linear and appositional skeletal growth both relative to soft tissue growth and relative to skeletal growth of control turkeys.

6. The rate of bone remodelling was reduced more than the rate of appositional growth so that bone cortical thickness was increased.

7. The changes in the skeleton effected by TA are consistent with the hypothesis that the drug acts by decreasing the rate of protein turnover, with catabolism being depressed more than anabolism.     

Inheritance of body weight and rate of gain in Japanese quail

1. The effects of hatch date, location and sex on the body weight and rate of gain in Coturnix coturnix japonica were examined.

2. The data conformed to a mixed model and adjustments were made for the fixed effects sex, hatch date and location. Adjustment improved the precision of the estimates by reducing the error variances significantly.

3. Rearing equal numbers of birds from each family at different locations made the interactions negligible.

4. Weight gain was greater if illumination intensity up to 35 d was less.

5. Females were not heavier on the 1st day but were heavier on the 14th and 35th days than males.

6. Variance components and genetic parameters were estimated.     

The relationship between hatching egg weight and subsequent performance of broiler chickens

Small eggs constitute a high proportion of the eggs laid by pullets. The literature shows that chick hatching weight is strongly correlated with egg weight, but evidence on the influence of egg weight on hatchability and subsequent performance of chicks is less certain.

The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship.

A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex.

Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability.

A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes.

Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age.

There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks.

Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality.

The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight.     

Effects of selection,over three and four generations,on meat yield and fatness in Muscovy ducks

1. Two experiments were undertaken to analyse the effects of selection for lowering carcase fatness and improving meat yield of Muscovy ducks. The control generation N and the selected generations N+ 3 and N+ 4 of the same heavy line (Grimaud) were reared under similar conditions.

2. We compared growth, carcase characteristics, chemical composition of breasts and plasma concentrations of very low density lipoproteins (VLDL), triglycerides and phospholipids.

3. Selection induced an increase of body weight ( + 8% to 10% at slaughter age), a decrease of abdominal fat percentage (? 10%) and an improvement of breast and thigh plus shank yields (+ 3% to 7% and + 4% respectively).

4. The lipid content of breast meat decreased in the selected ducks (? 14% to ?20%), particularly phospholipids and triglycerides. Breasts appeared paler and less red which suggested modifications of muscular fibre composition.

5. We found no significant correlations between plasma VLDL, triglyceride and phospholipid concentrations and carcase fatness. It therefore seems difficult to use these variables as selection criteria for lowering carcase fatness of Muscovy ducklings.     

Influence of stocking density and layer age on production traits and egg quality in Japanese quail

1. Japanese quail hens were housed from 6 to 26 weeks of age in cages providing areas of 150, 180, 210 and 240 cm²/bird.

2. Body weight gain, age at 50% egg production, mortality, hen‐day egg production and food conversion values showed significant improvement with proportionate increase in cage space per layer.

3. Egg weight gradually increased with age but shell thickness was influenced neither by age of the hen nor by stocking density.

4. Yolk index and colour were superior in the lowest stocking density (more cage space) group; other egg quality traits and egg weight were not influenced by stocking density.

5. The albumen index, internal quality unit, yolk index and yolk colour values increased with age.     

Gene expression profile of IGF1 and MSTN mRNA and their correlation with carcass traits in different breeds of geese at 70 d of age

1. The expression of insulin-like growth factor-1 (IGF1) and myostatin (MSTN) mRNA in breast and leg muscle was quantified in 70-d-old Taihu and Wanxi geese by using a Multiplex Competitive Fluorescent–PCR method and the correlations between mRNA levels and carcass traits were analysed.

2. IGF1 mRNA expression in breast muscle in Taihu geese was significantly higher than that in Wanxi geese and the MSTN mRNA level in leg muscle in Taihu geese was significantly higher than that in Wanxi geese.

3. There was no significant difference in breast muscle MSTN or leg muscle IGF1 mRNA expression between the two breeds.

4. Within the same breed, the IGF1 mRNA expression in leg muscle of male geese was significantly higher than that in female geese, and MSTN mRNA expression in leg muscle was significantly higher than that in breast muscle.

5. There was no difference in the IGF1 mRNA expression between tissues.

6. There was a positive correlation between IGF1 mRNA and MSTN mRNA and a negative correlation between IGF1 mRNA expression of breast muscle and leg muscle ratio.

7. In Wanxi geese, MSTN mRNA expression in leg muscle was negatively associated with body weight and leg muscle weight.     

Comparison of nutritive values of groundnut oil cake and Niger oil cake for laying pullets

1. The nutritive value of Niger oil cake (Guizotia abyssinica, Cass.) as a protein supplement for layers’ diets has been assessed.

2. Replacing groundnut oil cake (GNC) by Niger oil cake (NC) on an isonitrogenous basis, did not affect egg production, egg weight or the amount of food required per dozen eggs.

3. The percentage retention of nitrogen from diets containing 30% GNC or 30% NC was similar.

4. The ME value of NC used was 3025 kcal/kg.

5. It is concluded that NC can replace GNC in layers’ diets.     

Genetics of changes in economic traits during the laying year

Body weights, egg weights and egg numbers were measured at different ages in two distinct, fully pedigreed, random bred strains of White Leghorns over a period of 3 years. The heritabilities of the separate measurements and the genetic correlations between them were obtained by an analysis of variance and covariance. The principal findings were:

(i) The heritability of weight gain declined sharply with age over consecutive periods after 12 weeks. The genetic correlation of body weight at 12 weeks with gain in subsequent periods was low. There appeared to be sufficient genetic variance in growth rate in these later periods to alter the growth curve substantially by selection. For example, it should be possible to breed strains with a rapid early growth and low mature body size.

(ii) There was evidence of genetic variation in the change of egg weight with time. The genetic variation was, however, so low that in any selection programme to improve 28‐week egg weight without changing 44‐week egg weight the progress would be very slow.

(iii) Body weight at 12 weeks was genetically negatively correlated with sexual maturity. Its correlation with production in the first 44 weeks was positive in both strains, but not significantly different from zero.

(iv) Body weights after 28 weeks were apparently uncorrelated with egg production or sexual maturity.

(v) Egg weight and production traits show considerable heterogeneity of variance between years, probably partly due to their distribution not being normal.

(vi) The pattern of genetic variation appeared to differ significantly between the two strains so that correlated responses would not necessarily be the same.

(vii) There was a suggestion of maternal effects acting upon body weight but the evidence was somewhat contradictory and inconclusive due to the high standard error of the estimates.

(viii) None of the 15 traits measured regressed over the 3 year period of relaxation of selection.