Evaluation of body calcium and phosphorus composition of the Cobb 700 genotype during growth.

1. The amount of calcium and phosphorus in the empty, feather-free bodies of Cobb 700 breed males and females was measured from hatch to 15 weeks of age.2.

Evaluation of the potential growth and body composition of the Cobb 700 genotype.

1. The potential growth of the chemical and physical components of males and females of the Cobb 700 strain was measured from hatch to 15 weeks of age.2.

The response of turkeys to dietary balanced protein during two periods of growth.

1. Two experiments were conducted to measure the response of growing turkeys to dietary protein content. In the first, 960 sexed British United Turkey (BUT 6) poults were used to measure the response to balanced protein from 3 to 6 weeks of age.

Update and evaluation of the egg production model in laying hens.

The egg production model (EPM) described here is a mechanistic and stochastic model that simulates the amino acid and energy requirements of laying hens. It takes into account their potential rate of laying, and egg weight over time, and the composition of the feed provided. The model predicts feed intake based on the assumption that hens will consume enough feed to reach their genetic potential.

Evaluation of a mechanistic model that estimates feed intake, growth and body composition, nutrient requirements, and optimum economic response of broilers.

Efficient meat production is crucial in addressing global market demands and sustainability goals. Modeling production systems has gained worldwide attention, offering valuable insights for predicting outcomes and optimizing economic returns. In the poultry industry, researchers have developed mathematical models to predict animal performance and maximize profits.

The Response to Dietary Leucine in Laying Lens.

This study aimed to estimate the standardized ileal digestible leucine intake (SID-Leu, mg) in laying hens for maintenance, and to describe the response in laying hens to SID-Leu, thereby providing the information required to determine the optimum economic intake of SID-Leu for laying hens. Two nitrogen balance series, one balanced and the other unbalanced with respect to leucine (Leu), were used to estimate the SID-Leu requirement for maintenance using 36 roosters per series. The roosters were randomly distributed among the six levels of Leu with each level being replicated six times.

Review: When worlds collide - poultry modeling in the 'Big Data' era.

Within poultry production systems, models have provided vital decision support, opportunity analysis, and performance optimization capabilities to nutritionists and producers for decades. In recent years, due to the advancement of digital and sensor technologies, 'Big Data' streams have emerged, optimally positioned to be analyzed by machine-learning (ML) modeling approaches, with strengths in forecasting and prediction. This review explores the evolution of empirical and mechanistic models in poultry production systems, and how these models may interact with new digital tools and technologies.

Dietary energy:protein ratio influences the efficiency of utilisation of dietary protein by growing turkeys.

1. The following experiment was designed to confirm that the efficiency of dietary protein utilisation (ep) can be reduced when the AMEn to digestible crude protein (DCP) ratio of the feed falls below a critical level. In addition, whether the efficiency would be improved at high DCP contents through the addition of oil or starch was determined.

Composition of feathers and pulp of two broiler genotypes.

1. Cobb and Ross broilers (200 of each sex and breed) were fed four phases of diets formulated with balanced protein to match their amino acid requirements throughout growth. Ten birds per genotype were sampled and euthanised at two-weekly intervals from 14 to 112 d of age.

Gut capacity of broiler breeder hens.

1. Broiler breeders are subjected to qualitative or quantitative feed restrictions to prevent obesity, which causes major health and welfare problems. Diluting their feed by adding inert or low nutrient, bulky materials can reduce obesity, but the capacity of the gut needs to be determined to apply this strategy successfully.

The response of reproducing Japanese quail to dietary valine.

1. A feeding trial was conducted to measure the responses of Japanese quail to dietary valine. In total, 280 Japanese quail were randomly assigned to eight treatments giving seven replicates (cage - 35 cm length, 35 cm width × 15 cm high).

Combined Effect of Dietary Protein, Ractopamine, and Immunocastration on Boar Taint Compounds, and Using Testicle Parameters as an Indicator of Success.

This study investigates the combined effect of immunocastration, dietary protein level (low, medium or high) and ractopamine hydrochloride supplementation (0 or 10 mg/kg) on the adipose concentrations of androstenone, skatole and indole in pigs, and explores whether body mass, carcass fatness or testicular parameters may be indicators of boar taint in these carcasses. Immunocastration was successful in decreasing testicle functioning, and adipose androstenone and skatole concentrations, in all individuals. Immunocastration decreased testicle weight and length, seminiferous tubule circumference and epithelium thickness.

Prediction of maximum scaled feed intake in broiler chickens based on physical properties of bulky feeds.

1. A trial was conducted to investigate the capacity of broiler chickens to consume bulky feeds during three stages of growth. These phases were from 1 to 15 d, 16 to 30 d and from 31 to 45 d.

A description of the growth and moulting of feathers in commercial broilers.

1. Changes in feather length and weight and daily losses of down, contour feathers, remiges and retrices were studied in two commercial broiler strains to determine feather growth and moult in broilers up to 112 d of age. 2.

A description of the potential growth and body composition of two commercial broiler strains.

1. The potential growth of feathers and feather-free body and their chemical components was measured in two commercial broiler strains. 2.

The growth of turkeys 1. Growth of the body and feathers and the chemical composition of growth.

1. The potential growth of modern turkey genotypes was measured using male and female BUT 6 (BUT) and Hybrid Converter (HYB) strains. At one-day-old, 720 male and 960 female poults were randomly allocated to 48 littered pens in two houses with 30 males or 40 females of each strain per pen.

The growth of turkeys 2. Body components and allometric relationships.

1. The relationships between the main components of the body and body protein among males and females of BUT 6 (BUT) and Hybrid Converter (HYB) turkey strains were examined. 2.

Intermittent lighting improves resilience of broilers during the peak phase of sub-clinical necrotic enteritis infection.

Necrotic enteritis, either in its clinical or sub-clinical form is known to cause massive economic losses in the broiler chicken industry. Currently, the use of in-feed antibiotics as growth promoters is discouraged. Therefore, mechanisms to control NE through diet include reduction of digesta viscosity, promotion of lower pH in the gastrointestinal tract (GIT) through acidification of feed, production of short-chain fatty acids and overall stimulation of beneficial bacteria growth.

The effect of dietary energy:protein ratio, protein quality and food allocation on the efficiency of utilisation of protein by broiler chickens.

1. Various theories have been proposed to explain the reduced performance of broilers when given feeds excessively high in protein, but a satisfactory solution to this problem had, up to now, not been found. Three experiments were conducted to test the hypothesis that the efficiency of utilisation of protein (e) is a linear-plateau function of the ratio between the feed apparent metabolisable energy and digestible crude protein contents (AMEn:DCP) and that dietary protein quality, feed allocation and sex do not influence this relationship.

Growth performance, nutrient utilisation and carcass composition respond to dietary protein concentrations in broiler chickens but responses are modified by dietary lipid levels.

A total of ten experimental diets with protein concentrations ranging from 154 to 400 g/kg and two lipid levels (46 and 85 g/kg) with identical energy densities were offered to 240 male Ross 308 broilers from 7 to 28 d post-hatch. Growth performance was monitored and nutrient utilisation (apparent metabolisable energy (AME), N-corrected AME (AMEn), AME daily intake, AME:gross energy ratios, N retention) was determined. The weight gain response of broiler chickens to dietary protein concentrations in diets containing high and low lipid levels was diverse, with the relevant quadratic regressions being significantly different (P0·05).

Growth responses of entire and immunocastrated male pigs to dietary protein with and without ractopamine hydrochloride.

The interaction between dietary balanced protein, ractopamine (RAC) and Improvac (IMP) on the growth response of 120 individually penned male PIC© pigs was evaluated. The pigs entered the trial at 16 weeks of age and were assigned to 12 treatments using a 2×2×3 factorial design. Three balanced protein diets, formulated with standard illeal digestible lysine levels of 7.

The response of weaned piglets to dietary valine and leucine.

Valine (Val) is considered to be the fifth-limiting amino acid in a maize-soyabean meal diet for pigs. Excess leucine (Leu) levels often occur in commercial diets, which may attenuate the effect of Val deficiency because of an increased oxidation of Val. The objective of the present experiment was to determine the effect of increasing concentrations of Leu on the response of young piglets to dietary Val.

Description of a model to optimise the feeding of amino acids to growing pullets.

1. A nutrition model is described that may be used to optimise the amino acid nutrition of laying-type pullets prior to the onset of lay. It is not a method of optimising lifetime laying performance.

Predicted optimum ambient temperatures for broiler chickens to dissipate metabolic heat do not affect performance or improve breast muscle quality.

An experiment was conducted to test the hypothesis that muscle damage in fast-growing broiler chickens is associated with an ambient temperature that does not permit the birds to lose metabolic heat resulting in physiological heat stress and a reduction in meat quality. The experiment was performed in 4 climate chambers and was repeated in 2 trials using a total of 200 male broiler chickens. Two treatments compared the recommended temperature profile and a cool regimen.