Qualitative Restriction Research Articles

Cromo e restrições alimentares como estratégias alternativas a ractopamina para suínos em terminação

ABSTRACT: This study evaluated chromium and quantitative and qualitative feed restriction as alternative nutritional strategies to ractopamine in finishing barrows. Fifty barrows, genetically similar, with an initial body weight of 99.0 ± 4.3 kg and a final body weight of 117.2 ± 5.8 kg were used. The animals were distributed in a randomized complete block design with five nutritional treatments (Control; Rac = 10ppm ractopamine; Chromium = 0,8mg chromium yeast; Quality = qualitative restriction, 7.5% less net energy in the diet; Quanti = 15% quantitative reduction in feed supply), with five replicates and two animals per replicate. Chromium supplementation and quantitative feed restriction reduced feed, lysine, net energy, and crude protein intakes (P < 0.05). Chromium, ractopamine, and quantitative restriction improved feed conversion (P < 0.05). Supplementation with chromium and ractopamine and feed restriction did not influence the carcass characteristics of the pigs (P < 0.05). Quantitative feed restriction and supplementation of 0.8mg of chromium yeast are presented as potential alternatives to ractopamine in the diet of finishing pigs.

Caracterização e digestão anaeróbia dos dejetos de suínos submetidos a restrição alimentar ou suplementados com ractopamina ou cromo

Abstract The aim of this study was to characterize the production and anaerobic digestion of manure from finishing pigs subjected to feed restriction or supplemented with ractopamine or chromium (Cr). The waste came from 50 barrows in the finishing phase, aged ± 154 days, with a starting weight of 99.0 ± 4.4 kg and a final weight of 117.2 ± 5.8 kg. The experimental diets were as follows: control (conventional diet), qualitative restriction (7.5% reduction in net energy compared to the control diet), quantitative restriction (15% reduction in feed supply), Cr (0.8 mg), and ractopamine (10 ppm). The data were subjected to an analysis of variance using a randomized block design, in which the weeks of analysis were considered blocks (cofactors). There were no differences in manure production between the diets regarding natural matter (NM), dry matter (DM), mineral matter (MM), or organic matter (OM). Animals fed the control diet had the highest residue coefficient, and there was no difference among the other diets. No differences were observed among the diets regarding total solids, pH, or total nitrogen in the tributaries or effluents. The highest biogas yield (574 mL g-1) of added volatile solids (VS) was obtained in the digesters supplied with manure from animals fed a qualitatively restricted diet. It can be concluded that a qualitatively restricted diet results in higher manure production but with lower nitrogen and phosphorus excretion and higher biogas yields.

Which misspecifications persist?

We use an evolutionary model to determine which misperceptions can persist. Every period, a new generation of agents use their subjective models and the data generated by the previous generation to update their beliefs, and models that induce better actions become more prevalent. An equilibrium can resist mutations that lead agents to use a model that better fits the equilibrium data but induce the mutated agents to take an action with lower payoffs. We characterize which steady states resist mutations to a nearby model, and which resist mutations that drop a qualitative restriction such as independence.

Quantitative and qualitative feed restriction for broilers

The objective of this study is to evaluate the influence of five feed restriction programs (FRP) on broiler performance and carcass yield. 425 Cobb 500® broilers were distributed in a completely randomized design with five FRPs and five replicates with 17 broilers. The FRPs were: Program 1 (P1): consumption ad libitum (AL) of control diet from 14 to 42 days; P2: quantitative restriction (QTR) of 10% of AL consumption from 14 to 28 days and AL consumption from 29 to 42 days; P3: AL consumption from 14 to 28 days and QTR from 29 to 42 days; P4: qualitative restriction (QLR) of 10% of the level of crude protein and essential amino acids from 14 to 28 days and AL consumption from 29 to 42 days; and P5: AL consumption from 14 to 28 days and QLR from 29 to 42 days. The broilers of the AL treatment gained more weight (p≤0.01), but had a similar FCR (P>0.05) compared to broilers submitted to QTR from 29 to 42 days. In addition, broilers fed QTR from 14 to 28 days presented a lower FI and a better FCR (p≤0.01) in relation to broilers fed QLR of 14 to 28 (P4) and 29 to 42 days (P5). The broilers fed QTR of 14 to 28 days diet presented a similar FCR as broilers fed AL. The 10% reduction in AL consumption of 14 to 28 d is a viable economical alternative to feed broilers up to 42 days of age.

Feed Restriction on Productive Performance of Layer Chickens: A Review

Feed restriction is method of feeding where time, duration and amount of feed are limited, and it has an impact on whether a bird is capable of achieving the same productive performance as unrestricted birds. Feed restriction included of quantitative and qualitative restriction that is in quantitative to limiting the amount of feed daily given to the animals whereas a qualitative restriction is related to nutrient dilution in the diet. Different research results indicated that restriction of feed on layers production have controversial effect on feed intake, feed conversion efficiency, body weight gain, egg weight and quality. Overall, the potential of feed restriction programs as a management’s tool is important to increasing the egg production, egg quality, reduce maintenance requirements and improvement of feed efficiency in layers chickens. Also can be lead to economical saving in cost of feeding in layers chicken, thus may be usefulness for commercial layers chicks production farms. Keywords : feed restriction, Layers, performance, production DOI: 10.7176/JBAH/11-11-04 Publication date: June 30 th 2021

The effect of qualitative feed restriction in broiler breeder pullets on fear and motivation to explore

Restrictively fed broiler breeders are known to have increased motivation to explore and reduced fearfulness because hunger increases the motivation to search for and to acquire food, forcing the birds to face and engage with aversive stimuli that they would otherwise avoid. The aim of this study was to compare the effects of four dietary treatments on the level of fear and motivation to explore during rearing. In total, 1200 female breeder chicks of the genotype Ross 308 were housed in 24 pens, six pens of 50 birds per treatment. The treatments were: 1) standard feed (Control), 2) feed containing insoluble fibres (Insoluble), 3) feed containing a mix of both insoluble and soluble fibres (Mixed) and 4) standard feed supplemented with maize silage (Roughage). The treatments followed a qualitative restriction feeding strategy meant to allow the birds to consume larger portions of feed, increasing feeding time and reducing hunger and frustration. A novel object (NO) test was performed in the home pens at 6, 13 and 18 weeks of age. The test was performed two times at each age: 1 h before feeding and 5 h after feeding. In addition, at 7 weeks of age, 12 birds from each pen from all treatment groups were subjected to a tonic immobility (TI) test. We hypothesised that the Control birds would be less fearful in the TI test and keep a shorter distance to the NO than the treatment birds. For the NO test, there was an effect of the interaction between treatment and time of day on the likelihood of the birds to approach the NO at all ages (P ≤ 0.0001). At 13 weeks of age, in the afternoon, birds from the Mixed treatment were more likely to approach the NO compared to the birds from the Insoluble and Roughage treatments (P = 0.003) and tended to be more likely to approach than Control birds (P = 0.009). This suggests that the Mixed birds were in a hungrier state at that moment and therefore more willing to approach a NO than the birds fed the other dietary treatments. There was no effect of treatment on the latency to touch the NO or on the TI test. The results show minimal effects of the three qualitative dietary treatments on fearfulness and motivation to explore in female broiler breeders during rearing and, therefore, do not provide evidence of decreased sensation of hunger.

Effect of early feed restriction programs and genetic strain on humoral immune response production in broiler chickens

Two experiments were conducted to compare the immunocompetence of Cobb high performance and rustic Label Rouge broilers and the influence of reduced growth rates subsequent to feed restriction on the IgY anti-bovine serum albumin (BSA) response. In the first experiment (EXP), 360 broilers were assigned to 36 cages from 1 to 42 days of age. A completely randomized design was applied in a 3 × 2 factorial arrangement, with 3 groups (Label Rouge, Cobb ad libitum, and Cobb Restricted Intake), and 2 levels of energy (3,100 and 2,800kcal/kg); there were 6 replicates per treatment. In the second EXP, 384 Cobb 500 male broilers were randomly assigned to the following feed restriction programs from day 8 to 16: Control, fed ad libitum; Quantitative (80% of the control amount); By Time (fed for 8 h/d), and Qualitative (80% limiting nutrients) restriction. Blood samples were collected on days 35 and 42 (EXP 1) and weekly from day 7 to 42 (EXP 2) for IgY anti-BSA quantification. In EXP 1, the production of IgY anti-BSA was lower in the Cobb groups (P < 0.0001) than in the Label Rouge group, and higher in the Cobb Restricted Intake group (P < 0.0001) compared with the same genetic strain fed ad libitum. Birds fed the low energy diet presented lower (P ≤ 0.06) IgY anti-BSA, independent of genetics. In EXP 2, no difference (P > 0.05) was observed 1 wk after the first BSA inoculation. However, at day 28, birds in all feed restriction programs had higher (P < 0.05) IgY anti-BSA than the Control group fed ad libitum. At day 35, the greatest residual effect of IgY anti-BSA was observed in the Quantitative restriction group. No differences (P > 0.05) were observed between groups after 42 d. The 3 early feed restriction programs had beneficial effects on the humoral immune response. Overall, Quantitative restriction promoted a longer lasting IgY anti-BSA response. Lower growth rate, due to feed restriction or genetic potential, improves humoral immunity in broiler chickens.

Sex differences in basal hypothalamic anorectic and orexigenic gene expression and the effect of quantitative and qualitative food restriction

BackgroundResearch into energy balance and growth has infrequently considered genetic sex, yet there is sexual dimorphism for growth across the animal kingdom. We test the hypothesis that in the chicken, there is a sex difference in arcuate nucleus neuropeptide gene expression, since previous research indicates hypothalamic AGRP expression is correlated with growth potential and that males grow faster than females. Because growth has been heavily selected in some chicken lines, food restriction is necessary to improve reproductive performance and welfare, but this increases hunger. Dietary dilution has been proposed to ameliorate this undesirable effect. We aimed to distinguish the effects of gut fullness from nutritional feedback on hypothalamic gene expression and its interaction with sex.MethodsTwelve-week-old male and female fast-growing chickens were either released from restriction and fed ad libitum or a restricted diet plus 15% w/w ispaghula husk, a non-nutritive bulking agent, for 2 days. A control group remained on quantitative restriction. Hypothalamic arcuate nucleus neuropeptides were measured using real-time PCR. To confirm observed sex differences, the experiment was repeated using only ad libitum and restricted fed fast-growing chickens and in a genetically distinct breed of ad libitum fed male and female chickens. Linear mixed models (Genstat 18) were used for statistical analysis with transformation where appropriate.ResultsThere were pronounced sex differences: expression of the orexigenic genes AGRP (P < 0.001) and NPY (P < 0.002) was higher in males of the fast-growing strain. In genetically distinct chickens, males had higher AGRP mRNA (P = 0.002) expression than females, suggesting sex difference was not restricted to a fast-growing strain. AGRP (P < 0.001) expression was significantly decreased in ad libitum fed birds but was high and indistinguishable between birds on a quantitative versus qualitative restricted diet. Inversely, gene expression of the anorectic genes POMC and CART was significantly higher in ad libitum fed birds but no consistent sex differences were observed.ConclusionExpression of orexigenic peptides in the avian hypothalamus are significantly different between sexes. This could be useful starting point of investigating further if AGRP is an indicator of growth potential. Results also demonstrate that gut fill alone does not reduce orexigenic gene expression.

Meat properties and fatty acid profile of swine fed cashew bagasse bran in qualitative food restriction program

ABSTRACT The purpose of this study was to evaluate the effects of qualitative dietary restriction diet on carcass characteristics, meat quality, fatty acid profile, and performance of finishing pigs fed diets containing cashew bagasse bran. Forty pigs (20 females and 20 males) with initial weight of 60.00±5.24 kg of body weight (BW) were used. The diets were formulated with corn, soybean meal, cashew bagasse bran, vegetable oil, and mineral and vitamin mixture for finishing pigs. The experimental design was in [...]

Can diffusion-weighted imaging distinguish between benign and malignant pediatric liver tumors?

There are limited data on utility of diffusion-weighted imaging (DWI) in the evaluation of pediatric liver lesions. To determine whether qualitative and quantitative DWI can be used to differentiate benign and malignant pediatric liver lesions. We retrospectively reviewed MRIs in children with focal liver lesions to qualitatively evaluate lesions noting diffusion restriction, T2 shine-through, increased diffusion, hypointensity on DWI and apparent diffusion coefficient (ADC) maps, and intermediate signal on both, and to measure ADC values. Pathology confirmation or a combination of clinical, laboratory and imaging features, and follow-up was used to determine final diagnosis. We included 112 focal hepatic lesions in 89 children (median age 11.5years, 51 female), of which 92 lesions were benign and 20 malignant. Interobserver agreement was almost perfect for both qualitative (kappa 0.8735) and quantitative (intraclass correlation coefficient [ICC] 0.96) diffusion assessment. All malignant lesions showed diffusion restriction. Most benign lesions other than abscesses were not restricted. There was significant association of qualitative restriction with malignancy and non-restriction with benignancy (Fisher exact test P<0.0001). Mean normalized ADC values of malignant lesions (1.23x10-3mm2/s) were lower than benign lesions (1.62x10-3mm2/s; Student's t-test, P<0.015). However, there was significant overlap of ADC between benign and malignant lesions, with wide range for each diagnosis. Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.63 for predicting malignancy using an ADC cut-off value of ≤1.20x10-3mm2/s, yielding a sensitivity of 78% and a specificity of 54% for differentiating malignant from benign lesions. Qualitative diffusion restriction in pediatric liver lesions is a good predictor of malignancy and can help to differentiate between benign and malignant lesions, in conjunction with conventional MR sequences. Even though malignant lesions demonstrated significantly lower ADC values than benign lesions, the use of quantitative diffusion remains limited in its utility for distinguishing them because of the significant overlap and wide ranges of ADC values.

Optimization of SELEX: Comparison of different methods for monitoring the progress of in vitro selection of aptamers

Oligonucleotide aptamers are selected from libraries typically comprising up to 1015 different sequences by an iterative process of binding, separation, amplification and purification, called SELEX. During this process, the diversity of the oligonucleotide pool decreases until, presumably, only sequences with highest binding affinities towards chosen targets remain. This selection technique is time-consuming, labor-intensive and expensive. Though well posed in principles, the SELEX procedure is noise sensitive, due to amplification of unspecific-binding sequences, and it is not surprising that aptamer selection is often not successful in practice. In view of that, a follow-up of the progress of selection during its course with simple yet reliable methods is necessary. In this paper, we describe five independent assays to estimate the sequence complexity of SELEX pools including qualitative restriction fragment length polymorphism analysis, melting curve analysis, quantitative fluorescence intensity measurements of bound ssDNA, real time PCR quantification and pool dissociation constant analysis during the progress of aptamer selection against streptavidin. Properties and features of each method are discussed and compared. Pool dissociation constant analysis and sequencing serve as reference methods.

Positive quadrant dependence tests for copulas

AbstractIn this paper the interest is in testing the null hypothesis of positive quadrant dependence (PQD) between two random variables. Such a testing problem is important since prior knowledge of PQD is a qualitative restriction that should be taken into account in further statistical analysis, for example, when choosing an appropriate copula function to model the dependence structure. The key methodology of the proposed testing procedures consists of evaluating a “distance” between a nonparametric estimator of a copula and the independence copula, which serves as a reference case in the whole set of copulas having the PQD property. Choices of appropriate distances and nonparametric estimators of copula are discussed, and the proposed methods are compared with testing procedures based on bootstrap and multiplier techniques. The consistency of the testing procedures is established. In a simulation study the authors investigate the finite sample size and power performances of three types of test statistics, Kolmogorov–Smirnov, Cramér–von‐Mises, and Anderson–Darling statistics, together with several nonparametric estimators of a copula, including recently developed kernel type estimators. Finally, they apply the testing procedures on some real data. The Canadian Journal of Statistics 38: 555–581; 2010 © 2010 Statistical Society of Canada

P01-125 - Choking phobia: case report

Choking phobia is a condition characterized by intense fear of choking accompanied by avoidance of swallowing solid food, drinking and taking pills in the absence of anatomical or physiological abnormalities. Patients may present a significant weight loss, about which they usually feel uncomfortable.Fear respondents are elicited by the phobic stimuli and the patient learns to emit avoidance or escape behaviors as an attempt to reduce a hypothetical risk of choking. These escape and avoidance behaviors are characterized by a quantitative and qualitative restriction of food intake, as well as concerns about food texture, size of bite, and topographical changes in the eating response. Patients start to eat slowly, thus leading to social dysfunction.The authors propose to describe a case report, treatment and the results for this condition.R. is a 34 year old married male. Phobic symptoms started in 2005, after experiencing a choking incident with bone of fish. He progressively began limiting his intake of various food items by avoiding items he considered to be dangerous. Over the time he completely banished certain kinds of food from his diet and started to ingest all the aliments passed over a strainer. He refrained from eating at social events were he could not control the production of meals. This situation has implications in his marital life with constant conflicts.In spite of the insistence of the relatives he postponed around 3 years the search of medical treatment for this situation.He began pharmacological and psychotherapeutic treatment.

Qualitative-feed-restricted heavy swine: meat quality and morpho-histochemical characteristics of muscle fibers

To evaluate the effect of different levels of qualitative feed restriction (0, 5, 10, 15 and 20%) on pork quality and muscle morpho-histochemical characteristics, 60 castrated male swines were used. Ten animals were slaughtered at 89 kg BW. Other 50 pigs were fed experimental diets and slaughtered at 128 kg BW. Qualitative restriction increased pH45, and water holding capacity, and reduced the redness, yellowness and cholesterol concentrations of Longissimus lumborum. Quadratic tendency for oleic acid contents of loin and fiber cross-section area of Multifidus dorsi (P=0.08) were observed, with maximum point at 11-12% of restriction. No effect (P&gt;0.1) on percentage of M. dorsi fibers SO, FG and FOG was found. The meat from 128-kg-BW pig showed numerically higher values for colorness, water losses, and lipid content and lower shear force than 89-kg-BW pigs. Qualitative feed restriction for finishing swines neither affected negatively pork quality nor modified the muscle fiber profile.

Avaliação econômica do uso da restrição alimentar qualitativa para suínos com elevado peso de abate

O objetivo neste trabalho foi avaliar economicamente o uso da restrição alimentar qualitativa para suínos machos castrados em terminação sobre o desempenho e as características de carcaça de 60 animais. Dez suínos foram abatidos no início da fase experimental (89,0 ± 4,2 kg) e os demais, alimentados com rações contendo cinco níveis de restrição nutricional qualitativa (0, 5, 10, 15 e 20%), obtidas pela inclusão de casca de arroz finamente moída, até o final do experimento (127,8 ± 2,9 kg). Foram calculados os custos com alimentação durante o período experimental (R$alimento) e estimados os valores de receita bruta de cada carcaça de animais abatidos aos 128 kg (RBsuíno128kg) ou no início do experimento (RBmédia_suíno89kg). A partir destes três dados, foi calculado o resultado líquido (RL) do uso das dietas experimentais (RL = RBsuíno128kg - RBmédia_suíno89kg - R$alimento). Também foram analisadas as variações mensais dos preços do milho, do farelo de soja e do suíno, sendo determinado o preço do milho como o fator de maior impacto sobre a lucratividade do uso da restrição qualitativa. A equação de predição da probabilidade de aumento linear do resultado líquido pelo uso da restrição qualitativa foi determinada em função dos diferentes preços do milho - PM (valor de P RL = 0,392 - 0,625PM, R² = 0,73). Efeito significativo foi observado para preços do milho de cerca de quatro vezes ou mais acima do custo da casca de arroz. Assim, conclui-se que a viabilidade do uso da restrição qualitativa, até o nível de 20%, depende do cenário econômico, mas sobretudo do preço do milho, o principal ingrediente substituído nas rações ao empregar-se a restrição qualitativa, e de sua relação com o custo do resíduo utilizado para diluição energética.

Warm Spraying: An improved spray process to deposit novel coatings

Warm Spray is an atmospheric coating process through continuous impact and deposition of solid particles heated and accelerated by a supersonic jet controlled between 800~1900 K and 900~1600 m s − 1 . This paper introduces successful fabrication of dense and less-oxidized metallic titanium (Ti) coatings by Warm Spray and clarification of phenomena occurring upon the spray process. Temperature and velocity of an in-flight Ti particle were compared between measurement by the diagnostic instrument and calculation based on the fluid dynamics simulation. Deformation behaviour of particle from impact to deposition was analyzed through the finite element method (FEM). Densification of stacking particles was attained by applying bi-modal size distribution to the feedstock Ti powder. Qualitative restriction of changes in chemical composition of Ti coating obtained was demonstrated by elemental analysis and by calculation based on the oxidation model. Warm Spray enables various materials to fabricate coatings without thermal deterioration of the original characteristics such as purity and crystallographic phase.

Qualitative feed restriction on productive performance and lipid metabolism in broiler chickens

A trial was carried out to evaluate the effect of qualitative restriction at different rearing phases on liver fatness and plasma triglycerides without impairing the productive performance of broiler chickens. One hundred and seventy-six male chicks were randomly assigned to four treatments and reared in battery brooders (16 pens with 11 birds each) from 1 to 49-day-old. In the control group, chicks were fed a starter diet (1 to 28-day-old) with 3,300kcal ME/kg of diet and 22.5% CP; grower diet (29 to 42-day-old) 3,300kcal ME/kg of diet and 18.2% CP; and the finisher diet (43 to 49-day-old) 3,300kcal ME/kg and 18.2% CP. Three restrict groups were fed a low 2,800kcal ME/kg of diet and 24% CP from 7 to 14-day-old (treatment 1); from 7 to 21-day-old (treatment 2); and from 22 to 35-day-old (treatment 3). All treatments were fed control diet before and after the feed restriction period. Feed intake was not affected during the feed restriction period; nevertheless, weight gain was lower (P&lt;0.05) for chicks fed restricted diet from 7 to 21 and from 21 to 35-day-old. At the end of each restriction period, scores of liver for fatty infiltration were higher in restricted birds compared to control birds, although no changes were detected in plasma triglyceride levels. On the 49th day of age, less intracellular fatty infiltration was observed in the liver of previously restricted birds compared to control birds, and weight gain was also lower in the restricted groups. Moreover, triglyceride plasma levels were similar among treatments, but decreased in 12-hour-fasted broilers compared to non-fasted birds. The low energy:protein ratio diet affected weight gain and fatty infiltration in the liver, but had no effect on plasma levels of triglycerides.

A resampling approach to gender relations: the Rebešovice cemetery

Early Bronze Age society in Central Europe is often depicted as a society dominated by males. It is suggested that archaeological evidence is not always in agreement with this view. This study reports the analysis of mortuary variability at the Early Bronze cemetery Rebešovice in Moravia (Czech Republic) that uses computer-intensive resampling techniques. The results indicate that there are only minor differences in the mortuary treatment of females and males. There is neither a qualitative restriction of body treatment and objects buried with males, nor a quantitative emphasis on burials of males. In fact, burials of females are equipped with a higher number of bronze artifacts. Funerals of females were at least as significant social events as the funerals of males. We argue that the model of a male dominated community that used this cemetery is unwarranted. These findings do not refute the existence of gender-specific activities and roles that may be valued differently, but instead suggest that both females and males had access to resources from which they could draw power.

Effects of qualitative feed restriction during rearing on the performance of broiler breeders during rearing and lay

To prevent health and fertility problems associated with excessive weight gain, broiler breeders are severely feed restricted during rearing, which may affect welfare. We compared the effects of an experimental ad libitum feeding regimen based on qualitative restriction of food intake with conventional quantitative food restriction on the performance of female broiler breeders during rearing and lay. During rearing up to 20 wk of age, control birds were fed restricted amounts of standard broiler breeder mash once daily. Experimental birds had ad libitum access to the same standard mash mixed with 400 g of oat hulls/kg of feed and increasing concentrations of Ca propionate, an appetite suppressant. Mean total mash intake during rearing was 8.12 kg and did not differ between treatments. Both control and experimental birds showed an almost linear growth curve, treatment mean body weights were always within 100 g of the target weight line, and treatments did not differ for body weight uniformity. Groups were subjected to the same quantitative feed restriction from during lay. Feeding regimen during rearing did not affect number of eggs produced, egg weight, or egg quality up to 46 wk of age. We concluded that it may not be necessary to subject chicks to severe quantitative feed restriction to achieve desirable growth curves and body weight uniformity during rearing. Qualitative restriction of feed intake can achieve desirable growth curves in ad libitum fed chicks during rearing, and such a feeding regimen does not have negative effects on hen performance during lay.

Behaviour and welfare of broiler breeders fed qualitatively restricted diets during rearing: Are there viable alternatives to quantitative restriction?

This study investigated whether feeding female broiler breeders on qualitatively, rather than quantitatively, restricted diets during rearing could improve their welfare while also achieving desired growth rates. There were six treatments, each with four replicate pens of 12 birds. From 1 to 20 weeks of age, birds in a control treatment (T1) received a quantitatively restricted amount of a standard mash diet while birds in five additional treatments (T2–T6) had ad libitum access to experimental diets. The latter were based on standard mash and contained supplements of calcium propionate (CaP, an appetite suppressant), or oat hulls (OH, a dietary diluent), or both, that were increased with bird age. Birds received diets with either increasing CaP (T2), low protein and increasing CaP (T3), OH and increasing CaP (T4), CaP and increasing OH (T5), or increasing both CaP and OH (T6). Effects of treatment on body weight, behaviour, response to a feeding motivation test, and blood indices of stress were recorded. Results showed that different qualitative restriction treatments can limit growth rate close to target. T4, with 40% OH and increasing CaP, limited body weight closest to the desired level. Between 6 and 20 weeks of age, control birds (T1) spent 47–54% of their time in object pecking, which was almost absent (<1%) in all experimental treatment groups. Time spent inactive (sitting) and total time observed in all oral behaviours differed little between treatments. In a feeding motivation test, T1 birds consumed more food in 2 min after 2 or 4 h of food deprivation than did birds in any experimental treatment group. Treatment had no effect on the ratio of heterophils to lymphocytes or on the frequencies of other white blood cells. Plasma corticosterone level was raised in T5 birds, whose mean body weight was suppressed to below the commercial target for most of the study, but was otherwise unaffected by treatment. The results suggest that appropriate appetite suppression, with or without dietary dilution, can be an effective method of controlling broiler breeder growth rate. However, although there was some indication that such dietary treatments may be beneficial for bird welfare (e.g. the absence of abnormal pecking at non-food objects), other behaviours and physiological indices of stress did not differ consistently between experimental and control birds.