Quantitative Feed Restriction Research Articles

EFFECT OF FREE-RANGE AREA AND FEED RESTRICTION ON GROWTH PERFORMANCE OF HUNGARIAN LANDRACE GUINEA FOWL

Hungarian Landrace Guinea Fowls are famous for their excellent meat quality produced by traditional free-range farming. The study aimed to identify the optimal size of a free-range area for keeping Hungarian Landrace Guinea Fowl, and to examine its effect in combination with quantitative feed restriction on growth performance, 486 birds were randomly distributed into 18 cages. Free-range areas of different sizes (either 50 m2 or 15 m2 per bird, or without a running area) were provided from 6 weeks of age, and from 9 to 14 weeks,feed restriction at varying levels of 90%, 80%, 70% or ad libitum feeding was also applied. Body weight, body weight gain and feed conversion ratios were recorded every two weeks. Results showed that differing freerange area sizes and feed restriction had a substantial effect on the body weight of Hungarian Landrace Guinea Fowl, which was evident by the age of 10 weeks and continued until 14 weeks, where feed restriction negatively affected guinea fowl growth in free-range keeping. Guinea fowl provided with 15 m2 of free-range area per bird and fed ad libitum had the highest body weight (1378.52 ± 43.68 g) with relatively low feedconversion ratio (3.82 ± 0.14 kg feed per kg body weight gain) when compared with other experimental groups at the age of 14 weeks. The lowest body weight and feed conversion ratio was observed in groups with 15 m2 freerange area per bird and 70% feed restriction (1245.93 ± 38.64 g and 3.52 ± 0.12 kg feed per kg body weight gain), while the highest feed conversion ratio was detected in groups fed ad libitum and kept closed, without a free range area (4.34 ± 0.06 kg feed per kg body weight gain).

Impact of restricting feed and probiotic supplementation on growth performance, mortality and carcass traits of meat-type quails.

The objective of this study was to evaluate the effects of quantitative feed restriction, along with dietary supplementation with a probiotic blend (Protexin) as a natural growth promoter, on the performance, water consumption, mortality rate and carcass traits of meat-type quails. A total of 250 1-day unsexed quails were randomly allocated to five equal groups in a completely randomized design. The first group (A) fed a basal diet without any restriction (24hr/day); the second group (B1) fed the basal diet for 20hr/day; the third group (B2) fed the basal diet enriched with probiotic (0.1g/kg diet) for 20hr/day; the fourth group (C1) fed the basal diet for 16hr/day; and the fifth group (C2) fed the basal diet enriched with probiotic (0.1g/kg diet) for 16hr/day. Birds were fed ad-libitum from 0-14days of age, and then the feed restriction regimes started from 14 till 28days of age. Results showed that quails in the control-group consumed more feed and water than the other treatment groups (p<.01), however their body weights did not differ (p>.05) compared with the other treated groups. The best feed conversion values were achieved in quails supplemented with probiotic blend (B2 and C2) in comparison with the other groups (p<.01). Feeding probiotic had a positive effect on bird health which reduced the mortality rate. Further, mortality rate was significantly reduced (p<.05) by feed restriction, with or without probiotic supplementation. No carcass parameters were significantly affected (p>.05) by treatments. Our results show that quail could be reared under a feed restriction system, for 4-8hr daily, along with dietary supplementation of probiotic as growth promoter for better growth performance.

Nutritional efficiency of feed-restricted F1 Holstein/Zebu cows in early lactation

The quantitative feed restriction of lactating cows has been used in intensive production systems as a strategy to reduce production costs. However, the effects of this restriction in F1 Holstein/Zebu cows are unclear. The objective of this work was to evaluate the effect of quantitative feed restriction on nutrient intake and digestibility, nitrogen balance, feed efficiency, feed behavior, and productive performance in F1 Holstein/Zebu cows during early lactation. Sixty F1 Holstein × Zebu cows were used at the stage of initial lactation (50 ± 13days of lactation), and they had an initial body weight (BW) of 482 ± 43kg. The experimental arrangement adopted was a completely randomized design, with five feed restriction levels (3.39, 2.75, 2.50, 2.25, and 2.00% of BW) and 12 cows in each treatment group. In the short term (63days), there were reductions of 45.9% and 47.2% in dry matter intake (P < 0.01) and crude protein (P < 0.01), respectively, when the diet supply was limited from 3.39% BW to 2.00% of BW. There were declines in intake of ether extract (P < 0.01) and nonfibrous carbohydrates (P < 0.01), but there was no change in daily milk production (P = 0.44) nor the daily milk production corrected to 3.5% fat (P = 0.12); the averages were 14.01kg/day and 13.25kg/day, respectively. Considering the lower body weight loss, feed restriction is recommended up to 2.5% of the BW.

Nutritional efficiency of feed-restricted F1 Holstein/Zebu cows during the middle third of lactation.

ObjectiveThe objective of this study was to evaluate the effects of different levels of quantitative feed restriction on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance in F1 Holstein/Zebu cows during the middle third of their lactation.MethodsSixty F1 Holstein/Zebu cows with 111.5±11.75 days of lactation and an initial body weight (BW) of 499±30 kg (mean±standard error of the mean) were used. The experimental design was completely randomized with the following diet levels of feed restriction: 3.39%, 2.75%, 2.50%, 2.25%, and 2.00% of BW, with 12 replications for each level. The experiment lasted for 63 days, of which each period lasted 21 days with the first 16 days for diet adaptation followed by 5 days for collection of data and samples.ResultsFor each 1% of BW diet restriction, there was a decrease in dry matter intake of 5.26 kg/d (p<0.01). There was no difference in daily milk production (p = 0.09) under the restriction levels of 3.39% to 2.0% of BW. When corrected for 3.5% fat, milk production declined (p = 0.05) 3.46 kg/d for each percentage unit of feed restriction.ConclusionRestricting the feed supply for F1 Holstein/Zebu cows in the middle third of their lactation period altered nutrient intake, nitrogen balance and ingestive behavior but did not affect milk production or feed efficiency. However, considering the observed BW loss and decrease in milk production corrected for 3.5% fat, restriction of no less than 2.5% BW is recommended.

Intestinal microbiota of broilers submitted to feeding restriction and its relationship to hepatic metabolism and fat mass: Fast-growing strain.

The present study was conducted to verify how feed restriction affects gut microbiota and gene hepatic expression in broiler chickens and how these variables are related to body weight gain. For the experiment, 21-d-old Cobb500TM birds were distributed in a completely randomized experimental design with three treatments: T1. Control (ad libitum-3.176Mcal/kg ME-metabolizable energy-and 19% CP-crude protein); T2. Energetic restriction (2.224Mcal/kg ME and 19% CP) from 22 to 42days with consumption equivalent to control; T3. Quantitative restriction (70% restriction, i.e., restricted broilers ingested only 30% of the quantity consumed by the control group-3.176Mcal/kg ME and 19% CP) for 7days, followed by refeeding ad libitum from 28 to 42days. Ileum and caecum microbiota collections were made at 21, 28 and 42days of age. Hepatic tissue was collected at 28 and 42days old for relative gene expression analyses. At 43-d-old, body composition was quantified by DXA (Dual-energy X-ray Absorptiometry). Both feed restriction programmes decreased Lactobacillus and increased Enterococcus and Enterobacteriaceae counts. No differences were found in the refeeding period. Energetic restriction induced the expression of CPT1-A (Carnitine palmitoyltransferase 1A) gene, and decreased body fat mass. Quantitative feed restriction increased lipogenic and decreased lipolytic gene expression. In the refeeding period, CPT1-A gene expression was induced, without changing the broilers body composition. Positive associations were found between BWG (Body Weight Gain) and Lactobacillus and Clostridium cluster IV groups, and negatively associations with Enterobacteriaceae and Enterococcus bacterial groups. In conclusion, differences found in microbiota were similar between the two feed restriction programmes, however, hepatic gene expression differences were only found in quantitative restriction. Higher counts of Lactobacillus and Clostridium cluster IV groups in ileum are likely to be related to better broiler performance and low expression of lipogenic genes.

Effect of quantitative feed restriction and realimentation on growth, carcass traits and economics in stallfed Barbari kids

Four months old 24 Barbari kids were allotted randomly to ad lib. feeding up to 12 months age, 20% (mild) and 40% (moderate) feed restriction at 5th and 6th months (MMFR) and 20, 40, 60% (severe) feed restriction (MMSFR) each of 20 days duration during 5th and 6th months followed by realimentation up to 12 months age. At the end of realimentation, 4 kids from three groups were slaughtered and carcass traits evaluated along with its economics. The kids did not differ significantly in growth and carcass traits. Body weight change indicated that the occurrence of compensatory growth in feed restricted kids proportional to body weight loss occurred during restriction. The feed cost/kg gain was lowest in MMSFR kids followed by ad lib. fed and MMFR kids. Therefore, stallfed Barbari kids shall easily be maintained up to 60% lower feed for 60 days thereby increasing the profit of stallfed kid rearing.

Feed Restriction Modifies Intestinal Microbiota-Host Mucosal Networking in Chickens Divergent in Residual Feed Intake

Differences in chickens' feed intake may be the underlying factor influencing feed-efficiency (FE)-associated variation in intestinal microbiota and physiology. In chickens eating the same amount of feed, quantitative feed restriction may create similar intestinal conditions and help clarify this cause-and-effect relationship. This study investigated the effect of ad libitum versus restrictive feeding (85% of ad libitum) on ileal and cecal microbiota, concentrations of short-chain fatty acids, visceral organ size, intestinal morphology, permeability, and expression of genes related to nutrient uptake, barrier function, and innate immune response in broiler chickens with divergent residual feed intake (RFI; metric for FE). On day 30 posthatch, 28 low-RFI (good FE) and 29 high-RFI (poor FE) chickens across both feeding-level groups (n = 112) were selected. Supervised multigroup data integration and relevance network analyses showed that especially Lactobacillus (negative) in ileal digesta, Turicibacter (positive) in cecal digesta, and Enterobacteriaceae (positive) in both intestinal segments depended on chicken's feed intake, whereas the level of Anaerotruncus in cecal digesta was most discriminative for high RFI. Moreover, shallower crypts and fewer goblet cells in ceca indicated host-related energy-saving mechanisms with low RFI, whereas greater tissue resistance suggested a stronger jejunal barrier function in low-RFI chickens. Values corresponding to feed intake level × RFI interactions indicated larger pancreas and lower levels of ileal and cecal short-chain fatty acids in restrictively fed high-RFI chickens than in the other 3 groups, suggesting host physiological adaptations to support greater energy and nutrient needs of high-RFI chickens compensating for the restricted feeding. IMPORTANCE The impact of the FE-associated differences in feed intake on intestinal bacterial and host physiological parameters has so far not been clarified. Understanding the underlying principles is essential for the development of cost-effective strategies to improve FE in chicken production. Under conditions of quantitative feed restriction, low- and high-RFI chickens ate the same amount of feed. Therefore, this research helps in distinguishing intestinal bacterial taxa and functions that were highly reliant on feed intake from those that were associated with physiological adaptations to RFI-associated differences in host nutritional needs and intestinal nutrient availability. This work provides a background for further research to assess manipulation of the intestinal microbiota, host physiology, and FE in chickens by dietary intervention.

Feed restriction of F1 Holstein × Zebu cows in the final third of lactation modifies intake, nutrient digestibility, feeding behavior, and performance

ABSTRACT The objective of this study was to evaluate the effect of quantitative feed restriction level on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance of F1 Holstein × Zebu cows in late lactation. Sixty F1 Holstein × Zebu cows were used at the stage of late lactation (183.0±17.5 days of lactation) and with initial body weight (BW) of 499±30 kg. The experimental arrangement adopted was the completely randomized design, with five feed restriction levels [...]

Composition of weight gain in Nellore steers at different levels of feed intake

Thirty six Nellore steers, with an average initial age and weight of 20 months and 360 kg, were fed the same diet in three levels of dry matter intake: ad libitum or in two quantitative restriction levels 75g DM/kg BW0.75 or 60g DM/kg BW0.75 during 58 days (Phase 1) to evaluate the effects of feed restriction on performance and composition of weight gain in restriction and re-alimentation phases. All steers were fed ad libitum for 78 days (Phase 2). Body composition was estimated with the marker deuterium oxide, which allowed repeated measurements of the same animal and to study of its response to re-alimentation. Average daily gain in restriction phase reflected different weight gain rates provided by feed levels, being them 0.288 kg, 0.656 kg and 1.169 kg, respectively for 60g DM/ BW0.75, 75g DM/ BW0.75 and ad libitum. Feed efficiency raised according to level of feed intake in Phase 1 and no differences between treatments were observed in Phase 2. Dry matter digestibility did not differ between treatments in both Phase 1 and Phase 2, but was different between Phases for the same treatment with 78.8% in Phase 1 and 68.7% in Phase 2 for the treatment 60 g DM/BW0.75 and 77.8% in Phase 1 and 71.3% in Phase 2 for treatment 75 g DM/BW0.75. The empty weight gain, the daily deposition of water, ether extract, protein, ash and energy had an increase in their deposition according to the elevation of the level of feed intake in Phase 1. In Phase 2 there was no difference between the levels of diet intake for empty weight gain, chemical components deposition and retained energy in the gain. A short period of quantitative feed restriction imposed to Nellore steers could be used in beef cattle production system.

Fatty acid composition of maize silages from different hybrids

Fatty acid composition of maize silages from different hybrids

Impact of feed restriction, sexual class and age on the growth, blood metabolites and endocrine responses of hair lambs in a tropical climate

An experiment was conducted to evaluate the effects of feed restriction on the growth, blood metabolites and endocrine responses of hair lambs in a tropical environment. Thirty lambs were distributed in a completely randomized design in a 2×3×3 factorial scheme. Experimentaltreatments consisted of two sexual classes (15 intact males and 15 castrated males, 13.0±1.49kg initial BW and two months old), different levels of quantitative feed restriction (FR) (ad libitum, 300 and 600g/kg) and various ages (14, 19 and 23 weeks). Lamb age influenced the blood leptin (P<0.001), chloride, calcium, phosphorus and magnesium (P<0.05) concentrations. The blood insulin and glucose concentrations (P<0.001) were positively influenced by diet and age. The increased feed restriction resulted in a higher concentration of blood β-hydroxybutyrate (β-HB) (P<0.001). The blood urea nitrogen (BUN) concentration was influenced by diet (P<0.001), age (P<0.001) and the interaction of sexual class and age (P<0.01), with the highest concentrations in the oldest and castrated lambs. A positive correlation was observed between insulin and thyroxine in animals fed ad libitum (P<0.05). The thyroxin is present in low concentrations in the hair lambs raised in a tropical climate. Hair lambs exhibited significant changes in their growth, blood metabolites and endocrine responses, which enabled them to adapt to the feed conditions.

Effects of quantitative feed restriction on the performance of broiler chickens

A study was conducted to evaluate the effect of quantitative feed restriction on the performance and the production cost of broiler chickens. A total of 120, Indian River, day-old broiler chicks were randomly allocated into four dietary treatment groups such as 100% diet as control treatment and 90%, 80% and 70% diets, in floor pens. All treatments were replicated thrice with 10 birds each in a Completely Randomized Design. Broiler chickens were fed broiler starter diet from day 1 to day 21 and broiler finisher diet from day 22 to day 42. The results revealed that the body weight gain in the birds fed with 90% diet was significantly higher than those of control diet during finisher and overall phases and vice-versa during starter period. The feed intakes of birds were significantly decreased with the severity of feed restriction during all periods. However, significantly the lowest overall feed conversion ratio was reported in the birds fed with 70% diet. Furthermore, higher relative liver and lung weights were observed in the control treatment while they had lower relative heart weight. The spleen was significantly increased in the birds fed with 90% diet. It could be concluded that giving 90% of the recommended diet to the broiler chickens increases growth, immunity and income.

Effects of quantitative feed restriction and sex on carcass traits, meat quality and meat lipid profile of Morada Nova lambs

BackgroundAn experiment was conducted to evaluate the effects of feed restriction (FR) and sex on the quantitative and qualitative carcass traits of Morada Nova lambs. Thirty-five animals with an initial body weight of 14.5 ± 0.89 kg and age of 120 d were used in a completely randomized study with a 3 × 3 factorial scheme consisting of three sexes (11 entire males, 12 castrated males and 12 females) and three levels of feeding (ad libitum – AL and 30% and 60% FR).ResultsEntire males presented greater hot and cold carcass weights (P < 0.05), followed by castrated males and females. However, the hot carcass yield was higher for females and castrated males than for entire males. Luminosity values were influenced (P < 0.05) by sex, with entire males presenting higher values than castrated males and females. Females showed higher (P < 0.05) concentrations of linoleic acid and arachidonic acid in the meat of the longissimus thoracis muscle. The meat of animals submitted to AL intake and 30% FR showed similar (P > 0.05) concentrations, and the concentrations of palmitic acid, palmitoleic acid, stearic acid, oleic acid and conjugated linoleic acid were higher (P < 0.05) than those of animals with 60% FR. The meat of females had a higher ω6/ω3 ratio and lower h/H ratio, and females had greater levels of feeding. The meat of animals on the 60% FR diet had a greater ω6/ω3 ratio, lower h/H ratio and lower concentration of desirable fatty acids in addition to a greater atherogenicity index (AI) and thrombogenicity index (TI).ConclusionLambs of different sexes had carcasses with different quantitative traits without total influence on the chemical and physical meat characteristics. The lipid profile of the meat was less favorable to consumer health when the animals were female or submitted to 60% feed restriction.

Productive performance, body chemical composition, and deposition of 42-day-old quail for meat subjected to quantitative dietary restriction

This study aimed to assess the effect of quantitative dietary restriction during refeeding on the performance, body chemical composition, and deposition, weight gain of organs and carcass parts of quails reared for meat (Coturnix coturnix coturnix). A total of 144 quails, between 11 to 42 days old, were distributed in a completely randomized design, 4x2 factorial scheme, at four levels of feed restriction (ad libitum, 30%, 50% and 70% restrictions on the daily intake ad libitum) for both genders. Therefore, there was eight treatments with three replicates and six birds each. At the tenth day of age, the animals were housed in cages, where remained for four days under adaptation. Dietary restriction was applied between the days 15 and 35 while refeeding was carried out from day 36 to 42. Compensatory weight gain (CWG), i.e. weight gain of organs and carcass parts, and feed efficiency (FE) were improved for quails under feed restriction. Fat (F), crude protein (CP), protein deposition rate (PDR) and fat in females (FDf) and carcass retained energy in females (CREf) increased linearly as restriction levels decreased. Maximum estimates of feed intake for males (MFIm), compensatory weight gain for males (CWGm) and females (CWGf), feed efficiency for males (FEm), protein deposition for males (PDm) and carcass retained energy in males (CREm) were obtained with restriction levels of 43.56%, 30.56%, 63.93%, 62.63%, 80.25%, 1.94% and 09.34% if compared to ad libitum, respectively. As a result, we concluded that according to quantitative feed restriction level, significant increases in feed efficiency and body weight gain, as well as decreases in carcass fat throughout quail refeeding period. As for gender, given the existing sexual dimorphism, females lost greater body weight than males under dietary restriction, besides showing higher protein and fat gains in the carcass and an enhanced feed efficiency during refeeding.

Feed Restriction and Muscle Fibre Characteristics of Pectoralis Major in Broiler Chickens

Abstract The aim of the study was to evaluate the effect of one-week quantitative feed restriction (in days 8-14 of age) on histological characteristics of musculus pectoralis major in broiler chickens during the fattening period. Cockerels of Ross 308 (1215 chicken) were divided into 3 groups: ad libitum fed (AL; 3 × 135), restricted 80% of AL (R80; 3 × 135), and with limited feed intake 65% of AL (R65; 3 × 135). Eight cockerels per group were slaughtered in weekly intervals from day 14 of age till the end of experiment at 35 days to determine changes in the muscle fibre characteristics. The number of muscle fibres in pectoralis major decreased (P ≤ 0.001) with increasing age. Fibre cross sectional area was s ignificantly (P ≤ 0.027) affected by the interaction of group and age. At the end of feed restriction at 14 days all groups had similar fibre area (519-539 μm2), the differences between groups were observed at 35 days of age with the largest fibre area in R65 chickens (2296 μm2), while R80 did not differ from AL (1728 μm2 and 1667 μm2). There was no effect of feeding regime on giant muscle fibre incidence.

The effect of quantitative feed restriction on allometric growth in broilers

Feed restriction in broilers is aimed at preventing metabolic disorders, increasing feed efficiency, or manipulating carcass conformation. The purpose of the current study was to investigate the effects of modest graded levels feed restriction during the second and third wk of life. Mixed-sex chickens were raised in pens with 4 replications per treatment to 35 d of age. Chickens were fed ad libitum throughout the trial, or 90, 80, or 70% of expected ad libitum feed intake during the second wk of life, or 95, 90, 85, or 80% of expected ad libitum feed intake during the third wk of life. Feed intake, BW, ADG, and feed conversion ratio (FCR) were measured and weekly dissections were conducted to characterize allometric growth of the breast muscle, legs, abdominal fat pad, liver, gastro-intestinal tract (GIT), and heart. Feeding 70% of ad libitum during wk 2 and 80% during wk 3 reduced ADG during the restriction period and reduced BW at the end of the restriction period, but chickens exhibited complete compensatory growth within one wk after the restriction period. No significant effects of restriction treatment were found on BW, FCR, fat pad, empty GIT, breast muscle, heart, legs, and liver weight at d 35, but allometric growth curve for breast muscle was lower in birds fed 80 and 85% of ad libitum during wk 3, and for birds fed 70% of ad libitum in wk 2. Allometric growth curves for all body parts were different between males and females, except for the liver. Females had higher relative fat pad, breast muscle, and liver weight and a lower GIT and heart and leg weight compared with males at d 35. Feed restriction could differentially affect males and females. This study showed that feeding 70% of ad libitum in wk 2 might be beneficial to reduce fat pad, but later feed restriction in wk 3 may reduce breast muscle weight at broiler processing age.

Effect of Quantitative Feed Restriction on Some Physiological Parameters of Japanese Quails

The aim of this study to evaluate the effect of quantitative feed restriction on some physiological parameters of Japanese Quail. A total of 160 unsexed Japanese Quail aged 21 days were used for this study, divided randomly to four groups, each has four replicates as follows; control group (T1) feed ad libitum, treatment (T2), treatment (T3) and treatment (T4), 10%, 20% and 30% feed restriction of the control group value respectively for two weeks. On day 35 all the groups returned to the free feed ad libitum till the end of the treatment.Variables measured includes; productive, hematological and biochemical parameters.The results shows significant (p≤0.05) effect of feed restriction as the body weight decreased in the 4th, 5th and 6th week, on the other hand the weekly body weight increase, decreased significantly (p≤0.05) in the 4th week and increased significantly (p≤0.05) in the 6th week. The amount of feed taken in 4th, 5th decrease significantly (p≤0.05) and increased significantly (p≤0.05) at the 6th week, but the feed conversion ratio increased significantly (p≤0.05) in the 4th week and decreased (p≤0.05) in the 5th and 6th week, with significant (p≤0.05) increase in the relative growth rate in the 5th and 6th week in T4 . Cholesterol increased while triglycerides decrease significantly (p≤0.05). Hb and PCV decrease significantly (p≤0.05) compared to the control. We can conclude from the results that quantitative feed restriction programs may have some economic benefits with some health hazard through rising cholesterol levels, decreasing Hb and PCV values according to the intensity of feed restriction regimen.

Effet de la restriction alimentaire quantitative sur les performances de poulets de chair élevés en Tunisie

L’étude a été conduite pour étudier l’effet d’une phase de restriction alimentaire quantitative sur le poids vif du poulet de chair et évaluer les performances de croissance compensatrice. Quatre cents poussins d’un jour (Arbor-Acres) ont été élevés dans quatre parquets de 100 poussins. Ces unités ont été réparties aléatoirement en un lot témoin (T) alimenté ad libitum et trois lots restreints (A, B et C). Les poulets des lots A, B et C ont été limités respectivement à 90, 80 et 70 % de la prise alimentaire ad libitum entre 16 et 23 jours d’âge. Après le 23e jour d’âge, tous les poulets ont été alimentés ad libitum jusqu’à la fin de l’expérimentation (42 jours d’âge). Les résultats ont montré que pendant la phase de restriction, le poids corporel et le gain moyen quotidien ont été significativement différents (p &lt; 0,01) entre les quatre lots et qu’ils ont été plus élevés chez les poulets alimentés ad libitum que chez ceux des lots restreints. Le retard de croissance a été plus prononcé chez les poulets restreints à 70 %. Après le retour à l’alimentation ad libitum, la croissance compensatrice caractérisée par une croissance accélérée a été observée juste après la réalimentation pour les poulets limités à 70 % de la prise ad libitum, à 35 jours d’âge pour ceux ayant subi une restriction moins sévère (90 %), à la dernière semaine d’élevage pour le lot soumis à un niveau de restriction intermédiaire (80 %). L’efficacité alimentaire a été améliorée pour les lots restreints mais le poids corporel final des poulets a été inférieur à celui des poulets du lot alimenté ad libitum. Ainsi, une réduction intermédiaire de la quantité d’aliment consommée (de 20 % pendant huit jours) a permis d’atteindre un poids corporel final acceptable.

Quantitative Feed Restriction Rather Than Caloric Restriction Modulates the Immune Response of Growing Rabbits1–3

Background: Short-term feed restriction strategies are used in rabbits to reduce postweaning digestive disorders, but little is known about the involvement of the immune system in these beneficial effects.Objective: In the present study, the consequences of feed and energy restriction on immune response were investigated.Methods: At weaning, 320 male and female rabbits were assigned to 4 groups differing in dietary digestible energy (DE) concentrations and intake levels: a low-energy ad libitum–feed (LE100) group, a low-energy restricted-feed (LE75) group, a high-energy ad libitum–feed (HE100) group, and a high-energy restricted-feed (HE75) group. The high-energy groups consumed 10.13 MJ DE/kg of feed, whereas the low-energy groups consumed 9.08 MJ DE/kg (formulated values). Intake amounts for the restricted groups were 75% those of the ad libitum groups. Rabbits consumed these diets until age 63 d, after which they consumed feed ad libitum for 9 d. Ten rabbits per group and per age were killed at ages 42, 50, 63, and 72 d. Spleens and appendixes were weighed; Peyer’s patch surface area was determined by image analysis; plasma total immunoglobulin (Ig) G and anti-ovalbumin IgG; and fecal and plasma IgA concentrations were determined by ELISA; and ileal expressions of cytokines were measured by quantitative reverse transcriptase-polymerase chain reaction at ages 50 and 63 d.Results: The relative weight and size of the lymphoid organs were not affected by treatments. Concentrations of plasma total IgA (−41% at 63 d and −29% at 72 d), IgG (−22% at 72 d), and anti-ovalbumin IgG (−41% at 63 d) were lower with feed restriction. Fecal IgA concentrations were lower with quantitative restriction (−40%, −52%, and −65% at age 42, 50, and 63 d, respectively) and energy restriction (−56%, −46%, and −73% at ages 50, 63, and 72 d, respectively). Feed-restricted rabbits tended to have greater expressions of interleukin (IL) 1β and IL-2 and lower expressions of tumor necrosis factor α (P < 0.1).Conclusion: These results demonstrated that, in rabbits, restriction and, to a lesser extent, dietary energy concentration modulate gut immunity.

Feed-restricted broiler breeders: State-dependent learning as a novel welfare assessment tool to evaluate their hunger state?

This paper reports three experiments that aimed to validate the use of state-dependent learning (SDL) as a novel welfare assessment tool to evaluate the hunger state of feed-restricted broiler breeders.In each experiment, birds alternated every 2 days between two food rations: quantitative feed restriction (QFR) and ad libitum access to the same feed (AL). Each food ration was paired with a different, end of day, coloured food reward. It was predicted that the reward associated with hunger (QFR FR) would be preferred to the food reward associated with AL (AL FR) in a subsequent choice test. The SDL preference testing took place after 4 and 8 days of training. Each bird was tested twice (once per food ration fed on the test day).In experiment 1 (pilot, n=4), birds preferred the QFR-associated reward during both tests (mean (±S.E.M.) preference: QFR FR: 35.0 (±3.5)g; AL FR: 2 (±1.3)g, but differential food reward intake between hunger states during training confounded the results.In experiment two (n=12) a smaller food reward was used during training to try and equalise intake. The birds preferred the QFR FR in test 1 only (least significant difference (L.S.D.)=15.08, P<0.05). The mean (±S.E.M.) consumption in test 1 was: QFR FR: 31.6 (±4.3)g; AL FR: 9.41 (±2.3)g. However, differential reward intake continued to confound the findings.In experiment three (n=8), the food reward was made more palatable by feeding moist and food reward intake during training was equalised between hunger states. During testing, birds continued to show a significant preference in test 1 only (L.S.D.=13.73, P<0.05).It was concluded that SDL-derived preferences observed do exist but are not a robust phenomenon. Therefore, further research is needed to quantify factors influencing SDL development and maintenance before using SDL as a tool to assess hunger in feed-restricted broiler breeders.