Effect of early nutrient restriction on broiler chickens. 1. Performance and development of the gastrointestinal tract

Dietary effects of Sclerocarya birrea caffra seed cake replacing soyabean meal on physiology, meat and bone quality of indigenous chickens

This study investigated marula seed cake (MSC) as alternative protein source (APS) replacing soyabean meal (SBM) in indigenous chicken diets. Four hundred, 3-week-old Boschveld chicks were randomly allocated to 5 iso-energetic-nitrogenous maize and SBM-based grower diets with 0, 10, 15, 20, and 25 % MSC, each with 5 replicate pens of 16 birds, in a completely randomised design (CRD), for 9 weeks. Results showed that dietary MSC quadratically decreased bird overall feed intake (FI) (P < 0.001) and body weight gain (BWG) (P < 0.01) as it linearly decreased the weights of hot carcass (HCW; P < 0.05), spleen (P < 0.05), jejunum (P < 0.05), ileum (P < 0.001), and caecum (P < 0.001). In contrast, MSC increased chicken serum glucose (P < 0.05), cholesterol (P = 0.001) and phosphate (P < 0.05) as it decreased its amylase activity (P < 0.01). Also, it decreased bird meat lightness at 45 min (P < 0.05) and its yellowness at 45 min (P < 0.001) and 24 h (P < 0.001) whilst it increased its redness at 45 min (P < 0.01) and 24 h (P < 0.05) post-slaughter. In addition, MSC decreased chicken bone medial diaphysis (P < 0.05) as it induced no effects (P > 0.05) on overall feed conversion efficiency (FCE) and all other parameters. In conclusion, feeding of ≤ 15 % dietary MSC is nutritionally safe for indigenous chickens whilst detrimental on bird appetite, growth and meat yield, however without significantly affecting their physiology, at higher inclusion levels.

Effects of feeding silage of beet pulp or maize on the growth performance, meat quality, and production economics of broiler ducks

The present study aimed to compare the growth, meat quality, and production economics of Cherry Valley broiler ducks fed with a commercial diet along with silage from beet pulp or maize. In this study, 180 male Cherry Valley ducks were reared for 49 d. The control group (group C) was fed a commercial diet ad libitum. The experimental groups were fed a restricted amount of commercial diet and ad libitum beet pulp silage (group B) or maize silage (group M). For all groups, the growth performance and meat quality were analyzed, and their production costs were estimated. The beneficial effects of feeding maize silage on the growth rate were observed on d 29 to 49 in group M; moreover, both experimental groups showed lower feed intake than group C (P < 0.05). The feed conversion ratio was lower in the first rearing stage and during the entire experimental period in groups B and M than that in group C. Group M showed a higher European Production Efficiency Factor and European Broiler Index than group C (P < 0.05). The relative weight of the liver was higher in group C than that in the experimental groups (P < 0.05). Group M showed a higher L* value of leg muscles than group C (P < 0.05). Water-holding capacity was higher in leg muscles from ducks fed with silages (P < 0.05). The experimental groups had lower costs of commercial diets. Higher costs were observed for maize silage than for beet pulp silage. Carcass sales yielded the highest profit for group M and the lowest one for group C. Compared with the control group, the silage-fed groups showed a higher estimated profit by PLN 7.94 to 10.68 per duck (P < 0.05). Based on the beneficial production results, notably lower feed conversion ratio, no negative effects on carcass characteristics, and lower production costs, especially maize or even beet pulp silage in broiler duck rearing, could be recommended.

Effects of methionine and/or disaccharide injected in the amnion of geese on post-hatching pectoral muscle and small intestine development, glycogen reserves, jejunum morphology, and digestive enzymes activities

This study was conducted to investigate the effects of in ovo injection of methionine (Met) and/or disaccharide (DS) on post-hatching pectoral muscle and small intestine development, glycogen reserves, jejunum morphology, and jejunum digestive enzymes activities. A total of 600 fertilized eggs containing live embryo from geese were randomly assigned into 4 groups with 6 replicates and 25 eggs per replicate in a completely randomized design employing a 2 × 2 factorial experiment. Factors in 4 groups included noninjection, Met injection (5 g/L Met + 7.5 g/L NaCl), DS injection (25 g/L maltose + 25 g/L sucrose + 7.5 g/L NaCl), or DS plus Met injection (25 g/L maltose + 25 g/L sucrose + 5 g/L Met + 7.5g/L NaCl), respectively. In ovo nutritional injections were performed at day 23 of incubation, and the experiment until d 21 post-hatching. We found that in ovo feeding of Met increased relative weight of pectoral muscle and small intestine, jejunum alkaline phosphatase activities, and jejunum villus height and surface area. DS injection improved the relative weight of pectoral muscle, pectoral and liver glycogen contents, jejunum villus height, width, and surface area, and jejunum sucrase, Na⁺/K⁺ATPase, and alkaline phosphatase activities. In addition, Met plus DS injection synergistically improved jejunum villus height and surface area. Therefore, Met plus DS injection is a suitable strategy for improving intestinal parameters in gosling during post-hatching periods.

Impact of Treating Hatching Eggs with Curcumin after Exposure to Thermal Stress on Embryonic Development, Hatchability, Physiological Body Reactions, and Hormonal Profiles of Dokki-4 Chickens

Simple Summary

Curcumin has been used as a suitable feed supplement for poultry to improve several hematological and biochemical indicators, diminish heat stress, and increase antioxidant activity. This experiment evaluated the effects of incubation temperatures and spraying hatching eggs with curcumin during the incubation phase on chick embryo development, hatchability, physiological body reactions, and hormonal profiles of Dokki 4 chickens. The findings indicated that the relative water loss and dead after piping in the chronic incubation temperature group were significantly increased compared with the normal incubation temperature group. Post-hatch, the triiodothyronine level in the high incubation temperature group was significantly decreased than in the control group. Regarding curcumin treatments, relative water loss from eggs and the hatchability of fertile eggs in treated groups significantly increased, while body surface temperature significantly decreased compared with the control.

Abstract

This study evaluated the impact of incubation temperature and spraying hatching eggs with curcumin during the early embryogenesis phase on chick embryo developments, hatchability, physiological body reactions, and hormonal profiles of Dokki 4 chickens. A total of 720 fertile eggs were equally distributed into two groups. In the first group, the eggs were incubated at normal incubation temperature/NIT (37.8 °C and 55–60% RH) for up to 19 days of incubation, whereas those in the second group were incubated in the same conditions except from 6 to 8 day, in which they were daily exposed to chronic incubation temperature/CIT (39.0 °C) for 3 h. Each group was classified into four curcumin treatment doses; the 1st treatment (control) was sprayed with distilled water, while the 2nd, 3rd, and 4th treatments were sprayed with 250, 500, and 1000 mg curcumin/liter distilled water. The results indicated that the lowest hatchability of fertile eggs (%) was obtained in the CIT group (p = 0.02), whereas the highest body surface temperature/BST compared in the NIT group (p = 0.01). Regarding curcumin treatments, the percentages of heart, gizzard, spleen, and T3 hormone levels in the treated group were significantly increased, while the H/L ratio was significantly reduced (p = 0.001) compared with the control. At 8 weeks of age, the testes and ovary percentages in treated groups were significantly (p = 0.05) increased compared with the control. In conclusion, exposure of hatching eggs to high thermal stress (39 °C) during the incubation phase had deleterious effects on chick performance and T3 hormone level. Moreover, spraying hatching eggs had beneficial impacts on growth, reproductive organs, T3 hormone level, and reducing H/L ratio.

Effects of Energy-Restricted Feeding during Rearing on the Performance, Uniformity, and Development of Rugao Layer Breeders at the Initiation of the Laying Period

Simple Summary

Three major factors affecting productive performance of laying hens are BW, flock uniformity, and GIT development at the initiation of the laying period. Various feeding management practices to restrict feed intake of broiler breeders during the rearing phase to optimize BW for reproductive performance can improve BW uniformity. Hence, the feed restriction methods used for broiler breeders might be used to improve flock uniformity and the GIT development of laying hens. The objective of the study was to investigate the effects of energy-restricted feeding and switching to ad libitum feeding on the performance, uniformity, and development of Rugao layer breeders at the initiation of the laying period. Moderate energy restriction from 8 to 18 weeks of age and switching to ad libitum feeding can stimulate the development of the GIT and improve BW uniformity of layer breeders. Improved ECR was observed overall in the experiment. In addition, the BW of layer breeders recovered after the pullets were switched to ad libitum feeding for 3 weeks. These results provide a theoretical basis for the application of energy-restricted feeding in young layer breeders, which may have important practical importance for layer breeders because a better rearing cycle can be advantageous to production performance.

Abstract

The aim of this study was to assess the effects of energy-restricted feeding during rearing on the performance, uniformity, and development of layer breeders at the initiation of the laying period. A total of 2400 8-week-old Rugao layer breeders were randomly assigned to one of five groups (480 pullets per group) with eight replicates and were fed one of five diets that were nutritionally equal with the exception of apparent metabolizable energy corrected for nitrogen (AME_n) content (2850, 2750, 2650, 2550, and 2450 kcal AME_n/kg) from 8 to 18 weeks of age. The daily amount of feed was restricted to the absolute quantity of the diet consumed by laying hens fed 2850 kcal AME_n per kg diet ad libitum (control). From 18 to 21 weeks of age, all hens were fed a basal diet ad libitum. The body weight (BW) of the laying pullets decreased linearly with increasing energy restriction (p < 0.001) but recovered within 3 weeks of ad libitum feeding (p = 0.290). A gradual increase in the degree of energy restriction resulted in a gradual decrease in average daily weight gain (ADG) and a gradual increase in the feed conversion ratio (FCR) and energy conversion ratio (ECR) from 8 to 18 weeks of age (p < 0.001, p < 0.001, p = 0.008). In contrast, the ADG and ADFI (p < 0.001, p < 0.001) gradually increased, while the FCR and ECR (p < 0.001, p < 0.001) gradually improved from 18 to 21 weeks of age. From 8 to 21 weeks of age, ECR improved (p = 0.005) with an increasing degree of energy restriction. The energy-restricted feeding for 6 weeks to the end of the trial improved BW uniformity (p < 0.05). The relative length and circumference of tarsus (p < 0.001, p < 0.001), and the relative weights and lengths of the small intestine, duodenum, jejunum, ileum, and caeca increased linearly (p < 0.001, p = 0.012, p < 0.007, p = 0.012, p = 0.040; p < 0.001, p = 0.003, p = 0.032, p = 0.029, p = 0.040) with increasing energy restriction at 18 weeks of age. After switching to ad libitum feeding for 3 weeks, the relative weights and lengths of the small intestine, duodenum, and jejunum of laying pullets increased linearly with increasing energy restriction (p < 0.001, p = 0.016, p = 0.011; p = 0.009, p = 0.028, p = 0.032). In conclusion, moderate energy restriction (85.97%, 2450 vs. 2850 kcal AME_n/kg) from 8 to 18 weeks of age and switching to ad libitum feeding from 18 to 21 weeks of age can be used to improve BW uniformity and stimulate the development of the duodenum and jejunum of native layer breeders at the initiation of the laying period without compromising BW.

Impact of acute short-term high thermal stress during early embryogenesis on hatchability, physiological body reaction, and ovarian follicles development of quails

This experiment aimed to evaluate the impact of continuous and intermittent thermal stress during early embryogenesis on hatchability, physiological body reaction, ovary weight, and follicle development of quails. A total of 540 eggs were divided into 3 equal groups (3 groups × 6 replicates × 30 eggs). In the first group (control), eggs were incubated at normal incubation conditions (37.5°C and 50–55% relative humidity) from day 0 till hatching. In the second group (continuous thermal stress [CTS]), eggs were daily exposed to 39.5°C and 50 to 55% during the early embryogenesis for 3 successive days (E4–E6) for 3 h (12:00–15:00). In the third group (intermittent thermal stress [ITS]), eggs were daily exposed to 39.5°C and 50 to 55% during the early embryogenesis for 90 min (12:00–13:30) then temperature was returned to 37.5°C for 60 min (13:30–14:30) after that the temperature was raised again for 39.5°C for 90 min (14:30–16:00) daily for 3 successive days (E4–E6). The findings showed that the highest relative water loss form egg (RWL/%) at 6 d of incubation was obtained in the CTS group (P ≤ 0.05). The hatchability rate was significantly (P ≤ 0.05) decreased in the thermal-treated groups compared with the control group. The body surface temperature and cloacal temperature in the CTS and ITS groups significantly (P ≤ 0.001) increased compared with the control group. Chick weight (g) at 5 wk old, total weight gain, daily weight gain were significantly lower (P ≤ 0.05) in the CTS group compared with the control group. Triiodothyronine (T3) hormone concentration and globulin level were significantly (P ≤ 0.05) lower in the CTS and ITS groups compared with the control. The ovarian follicle weights (first, second, third, fourth, and fifth) and the diameter of the large follicle (fifth follicle) were significantly (P ≤ 0.01) decreased by increasing incubation temperature. From these findings, it could be concluded that the hatchability and body weight at sexual maturity for quails produced from eggs exposed to CTS and IST were significantly decreased by 8 and 2.1% as well as 2.98 and 2.1%, respectively, compared with the control group.

Feeding dihydroquercetin and vitamin E to broiler chickens reared at standard and high ambient temperatures

The use of natural antioxidants, in particular polyphenols such as dihydroquercetin (DHQ), in animal nutrition has recently increased in popularity. This may partly be due to the risk of increased incidences of heat stress associated with raising livestock in warmer ambient temperatures, facilitated by global warming, reducing antioxidant capacity. The current research demonstrates the effect of dietary DHQ, vitaminEand standard or high ambient temperatures on growth performance, energy and nutrient metabolism, gastrointestinal tract (GIT) development, jejunal villus morphometry and antioxidant status in broiler chickens. Each of the four experimental diets was fed to 16 pens of five birds, which were allocated to four rooms (four pens in each room). The temperature in two rooms was maintained at aconstant 35°C (high temperature; HT), and the temperature in the other two rooms was gradually reduced from 27°C at 7 dof age to 22°C at 20 dof age (standard temperature; ST). Rearing birds at HT reduced feed intake, weight gain, weight of small intestine, total GIT, liver, spleen, heart, villus height, villus surface area and lowered blood glutationperoxidase (GSH-Px). Dietary DHQ increased blood GSH-Px and total antioxidant status, increased heart weight and reduced caecal size. When fed separately, DHQ and vitamin E improved hepatic vitamin E concentration. Feeding vitamin Eincreased spleen and liver weights. When fed together, DHQ and vitamin Ereduced villus height, villus height to crypt depth ratio and villus surface area. Temperature and antioxidants did not affect energy and nutrient metabolism. There were no effects of dietary antioxidants on growth performance of broiler chickens and there were no mortalities. At present, it is unclear if feeding antioxidants (in particular DHQ) at different levels, using different dietary formulations, and rearing birds under arange of environmental conditions may be effective at enhancing production performance and bird health in hot ambient climates.

Interactions between egg storage duration and broiler breeder age on egg fat content, chicken organ weights, and growth performance

Egg storage and breeder age are between the most important factors affecting egg lipids, chicken quality, and posthatch performance. To evaluate these factors, including their interaction, the impact of egg storage duration (5, 12, and 19 D), and breeder age (47 and 67 wk) was investigated in Arbor Acres broiler eggs and chickens. Total yolk fat content, chicken organ development at hatch and at 6 D of age, and posthatch performance (at 7 D and 35 D of age) were determined. Total fat content in fresh yolk was lower in 12 and 19 D stored eggs than in 5 D stored eggs (Δ = -2.42% on average). In hatchlings, the heart percentage was not affected by storage duration in the younger flock but was higher after 19 D than after 5 and 12 D of storage in the old flock (Δ = +0.09% on average). Residual yolk weight was higher after 12 D egg storage than after 5 D egg storage (Δ = +1.7 g), with 19 D egg storage in between. Liver and intestine percentage decreased with storage duration. Residual yolk weight (Δ = +1.09 g) and liver percentage (Δ = +0.18%) were higher in old breeders than in younger breeders. At day 6, chicken BW, yolk free body mass, liver percentage, and intestine percentage interacted between egg storage duration and breeder age with the strongest effects in chickens from older breeder after 19 D of storage. Heart percentage was lower after 19 D compared with 5 and 12 D of storage (Δ = -0.05% on average). Feed intake and feed conversion ratio were higher between day 0 to 7 and 0 to 35 after 19 D than after 5 D egg storage (Δ19-5 D = +12 g and +199 g; +0.11 points and +0.09 points, respectively). It can be concluded that when it is needed, eggs from younger breeders should be stored for a prolonged period (≥12 D) rather than those from older breeders.

Evaluation of an insect meal of the Black Soldier Fly (Hermetia illucens) as soybean substitute: Intestinal morphometry, enzymatic and microbial activity in laying hens

This research investigated the ileum morphometry and enzymatic activity, the caecal volatile fatty acid production and the apparent nutrient digestibility in laying hens fed a Hermetia illucens larvae meal (HILM) as a complete replacement of diet soybean meal (SBM). The hens fed HILM exhibited a lower live weight (P<0.05) and a higher incidence of the full digestive tract (P<0.05) than the SBM group. In the duodenum, the maltase exhibited a higher (P<0.05) activity in the HILM group while the intestinal alkaline phosphatase (IAP) had a higher (P<0.05) activity in the SBM group. In the ileum, the maltase and saccarase had a higher activity in the HILM hens (P≤0.01) while the IAP and ɤ glutamil transferase had a higher activity in the SBM group (P<0.05 and P<0.01, respectively). The HILM group showed a higher (P<0.05) villi height in the duodenum, while the opposite happened in the jejunum and the ileum. Only in the ileum the crypt depth resulted higher (P<0.05) in the HIML group than in the SBM. The higher production of acetate (P<0.05) and butyrate (P<0.01) affected the total production of volatile fatty acids of the HILM group. The coefficient of apparent digestibility of dry and organic matter as well as of crude protein was higher (P<0.05) in SBM group. The total replacement of SBM with HILM in laying hens diet from 24 to 45weeks of age resulted in a higher caecal production of butyric acid while the enzymatic activities of brush border membrane were partially reduced.

Vitamin A deficiency induces morphometric changes and decreased functionality in chicken small intestine

The effect of vitamin A on chicken intestinal mucosal morphology and functionality was tested in relation to severe and mild vitamin A deficiency and vitamin A repletion. Compared with rats and mice, chickens have a very quick response to a deficient dietary intake. Severe vitamin A deficiency altered the small intestine of chickens at both the biochemical and the morphological levels. It caused the loss of mucosal protein, reduced villus height and crypt depth and diminished activities of disaccharidases, transpeptidase and alkaline phosphate (EC 3.1.3.1). The ratios RNA-.DNA, RNA:protein and protein:DNA, and the DNA concentrations in 1 g intestinal tissue, together with morphological measurements, provided knowledge about the pattern of lesion. The results indicated that (1) lack of vitamin A influenced cellular hyperplasia as it caused an increase in DNA content and in the number of enterocytes per villus; (2) lack of vitamin A influenced cellular hypertrophy as it decreased the protein:DNA ratio. There was no difference in mucosal enzyme activity between the two deficient groups. The repletion group exhibited a remarkable increase in mucosal enzyme activity only 4 d after switching to the control diet. The evidence presented in our paper suggests that the low vitamin A supply interferes with the normal activity of chicken intestinal mucosa as it influences the processes of proliferation and maturation of enterocytes.

Effects of the level and duration of feeding restriction on carcass components of broilers

Abstract. The effects of the restriction of the advised daily feed intake (ADFI) during 1 or 2 weeks on broiler body weight (BW) and carcass composition were studied. A total of 150 1-day-old male broilers (Ross-308) were randomly allotted to a control and four experimental treatments with three replicates per treatment. Broilers were subjected to a feeding restriction equal to 75 and 50 % of ADFI, either for a 7- or a 14-day period, between the 7th and 14th and 7th and 21th day of age, respectively. The BW and carcass composition were determined on day 42. From the findings, neither of the two levels of restriction nor the two time intervals had significant effects (P > 0.05) on the BW or breast and leg weight and proportion, liver and most of the body components. However, the feeding treatments show a tendency (P = 0.078) to influence the BW, with birds fed 75 % of ADFI for 14 day being heavier than the control group. For eviscerated carcass weight, an effect (P = 0.002) was observed, with birds fed 75 % of ADFI for 14 day having heavier carcasses (P < 0.05) than those in control group. The abdominal fat, both with regard to weight and proportion, was slightly influenced by dietary treatments (P > 0.05). From our results, it can be concluded that the applied feeding restrictions have a neutral or slightly beneficial effect on broiler growth traits and carcass composition.

Development of ileal cytokine and immunoglobulin expression levels in response to early feeding in broilers and layers

Provision of feed in the immediate posthatch period may influence interaction between intestinal microbiota and immune system, and consequently immunological development of the chick. This study addressed ileal immune development in response to early feeding in 2 chicken breeds selected for different production traits: broilers and layers. Chicks of both breeds either received feed and water immediately posthatch or were subjected to a 72-h feed and water delay. Ileal cytokine and immunoglobulin mRNA expression levels were determined at different time points. Effects of early feeding were limited, but breeds differed strikingly regarding cytokine and immunoglobulin expression levels. Cytokine expression levels in broilers were low compared with layers and showed a transient drop in the second to third week of life. In contrast, broilers showed considerably higher expression levels of IgA, IgM, and IgY. These findings indicate that the 2 breeds use different immune strategies, at least on the ileal level.

Effect of Two-step Time-restricted Feeding on the Fattening Traits in Geese

The present study was conducted to determine whether the two-step time-restricted feeding improves the fattening traits of one-step time-restricted feeding in geese. Thirty-six 8-wk-old geese were allotted into one of three groups. Group R1 (the 1-step restricted feeding group) was allowed access to feed for 2 h in the morning from 8 wk to 14 wk of age. Group R2 (the 2-step restricted feeding group) was treated as Group R1, but was additionally fed for 2 h in the afternoon from 12 wk to 14 wk of age. Group C (the control group) was fed ad libitum from 8 wk to 14 wk of age. Feed intake and body weight (BW) were recorded daily and weekly, respectively. At 14 wk of age, the blood samples were collected to determine the fasting plasma levels of glucose, triacylglycerols and uric acid before sacrifice. The results showed that daily feed intake (DFI) was lower, feed efficiency (FE) was higher in both Groups R1 and R2 than in Group C, and daily gain (DG) in Group R2 was higher than in Group R1 during the whole experimental period (p<0.05). Group R1 exhibited lower abdominal and visceral fat weights in carcass than did Group C (p<0.05), and Group R2 was in intermediate. The fasting plasma glucose levels in Group C were higher, and triacylglycerol levels in Group R1 were higher, compared with the other groups (p<0.05). It is concluded that time-restricted feeding in the fattening period not only increases FE but reduces DFI, and the additional meal during the late fattening period improves the DG without the expense of FE in geese.

Posthatch development of intestinal morphology and digestive enzyme activities in domestic pigeons (Columba livia)

The gastrointestinal tract plays an important role in studies of avian ontogenies because of its key function in nutrient intake. The pattern of intestinal development during postnatal growth in domestic pigeons (Columba livia), as an altricial bird, would be different from the pattern observed in precocial poultry. In this study, the intestinal morphology, mucosal enzyme activities, and pancreatic enzyme activities were determined from hatch to 14 d of age in pigeons. Rapid morphological development was observed immediately after hatching. Villus area and crypt depth increased in parallel in the duodenum and jejunum and more slowly in the ileum. Mucosal enzyme activities per gram of duodenum, jejunum, and ileum varied significantly with segment and age. There were also intestinal segment × age interactions, in which enzyme activity increased most dramatically in the jejunum as compared with the duodenum and ileum for sucrase and maltase activity from day of hatch to 8 d, and for alkaline phosphatase activity through 14 d. However, aminopeptidase-N activity increased most dramatically from day of hatch to 3 d in the ileum as compared with the duodenum and jejunum. Changes in carbohydrate-digesting enzymes activity in duodenum, jejunum, ileum, and pancreas are more pronounced than for protein-digesting enzymes activity from 3 d after hatching. Intestinal total enzyme activities exhibited a steady increase, which was highly correlated with BW. Pancreatic enzymes indicated patterns somewhat similar to those for intestinal enzymes. It was concluded that development of the absorptive area and the capacity for hydrolysis in the duodenum, jejunum, and ileum was rapid immediately after hatching, although rates of development were different in the 3 segments. Young pigeons differ from poultry, in whom intestinal and pancreatic digestive enzyme activities per gram of tissue are generally constant or decline during postnatal development. Also, the data seem consistent with the idea that intestinal hydrolysis may be a determining step in digestion and hence growth.

Gross intestinal adaptations in relation to broiler performance during chronic aflatoxin exposure

The present trial was conducted to study some morphological, digestive, and electrophysiological variables of the small intestine during chronic exposure of broilers to aflatoxin B(1) (AFB(1)). Ross 308 male chicks (7 d old) were randomly allotted to control (no AFB(1)), low AFB(1) (0.07 mg of AFB(1)/kg), or high AFB(1) (0.75 mg of AFB(1)/kg) diet. The high AFB(1) diet resulted in reduced (P ≤ 0.002) bird performance during the first 4 wk of exposure, whereas the low AFB(1) diet temporarily reduced (P = 0.034) the bird performance during wk 3 of exposure. During wk 4 of exposure, a linear (P ≤ 0.013) decrease in the unit weight of both the duodenum and jejunum was observed with increasing levels of AFB(1). This reduction in unit weight appeared to progress from the proximal (duodenum) to the distal (jejunum) small intestine with increase in the length of exposure and was not accompanied by modulation of electrophysiological variables in jejunal epithelium. Response from amiloride, a specific blocker of epithelial sodium channel, was also similar among jejunal epithelia of birds under different treatments. Interestingly, a compensatory linear (P ≤ 0.002) increase in the length of the duodenum and jejunum under high AFB(1) diets was noted to occur during wk 4 of exposure. Thus, retention of DM and nitrogen was not negatively affected by the AFB(1) diets. These data indicate that the intestine in broilers may adapt to an ongoing dietary challenge to AFB(1).

Effects of an organic acid mixture and methionine supplements on intestinal morphology, protein and nucleic acids content, microbial population and performance of broiler chickens

A study was carried out to investigate the effects of dietary supplementation of an organic acids mixture and two methionine supplements on intestinal morphology, protein and nucleic acids content, microbial population and performance of broiler chickens. Six hundred unsexed day-old Ross 308 broiler chicks were used in a factorial arrangement (3 × 2) based on a completely randomised design by four replicates with 25 chicks in each. Experimental diets consisted of: 0% organic acid mixture + DL-methionine (Treatment 1), 0% organic acid mixture + Alimet (Treatment 2), 0.5% organic acid mixture + DL-methionine (Treatment 3), 0.5% organic acid mixture + Alimet (Treatment 4), 1% organic acid mixture + DL-methionine (Treatment 5) and 1% organic acid mixture + Alimet (Treatment 6). A significant increase in jejunum mucosal DNA content was found by using 1% of organic acid mixture compared with those by other levels of organic acids at 21 days of age (P < 0.05). Also Treatments 5 and 6 had a higher mucosal DNA content than other treatments (P < 0.05) in a similar period. While at grower stage, the results have shown that protein content, protein/DNA and protein/RNA ratio by 0.5 and 1% of organic acids mixture significantly increased compared with those in the 0% level (P < 0.05). The addition of 1% level of organic acid mixture significantly increased villus height compared with 0 and 0.5% level of organic acid mixture at 21 days of age (P < 0.05). Highest and lowest villus heights were obtained by Treatments 1 and 6 (P < 0.05). Crypt depth increased by 0.5 and 1% of organic acid at 21 and 42 days of age (P < 0.05). Villus surface was significantly increased by 1% of organic acid mixture compared with that by 0% level at 21 days of age. The use of organic acid levels especially 1% resulted in an increase in lactic acid bacteria and decreased Enterobacteriaceae counts in the ileum of broiler chicken (P < 0.05). Better bodyweight and feed conversion ratio were obtained (P < 0.05) by 0.5 and 1% of organic acids mixture, although no response was found in feed intake and mortality in this respect (P > 0.05). The results of this study have shown improved reactions on intestinal morphometrical parameters and microflora atmosphors, by using 1% organic acid mixture. In contrast no differences were found between Alimet and DL-methionine in all tested parameters.

Dietary amino acid levels and feed restriction affect small intestinal development, mortality, and weight gain of male broilers

This study investigated the effect of 2 different dietary amino acid treatments and feed restriction in early life versus a control treatment on development of the small intestine segments (weights), mortality, and broiler performance. Each treatment was applied to 6 cages with Ross 308 male broilers and to 6 cages with Cobb 500 male broilers with 24 birds per cage. A control treatment (100% ideal protein) was compared with a treatment with 30% extra ideal protein, a treatment with daily adjustment of the dietary amino acid level and profile, and a feed restriction treatment. The protein treatments were applied from 0 to 14 d of age. The feed restriction was applied from 4 to 21 d of age. Restriction was 15% from d 4 to 14 of age and diminished with equal daily steps thereafter to 5% at 21 d of age. Birds were weighed and dissected for evaluation of small intestine weights at 6, 9, 14, and 36 d of age. Feed intake restriction reduced leg problems in Ross and Cobb broilers. Extra dietary protein reduced leg problems in Ross broilers only. The present experiment does not show that small intestinal weight development is related to mortality. Thirty percent extra dietary ideal protein increased duodenum weight between 6 and 9 d of age. This was not further increased by the daily optimization of the dietary amino acid level and profile. The increased duodenum weights coincided with an improved BW gain. This indicates that duodenum weight may be important in facilitating BW gain in young broilers. Thus, it may be worthwhile to pay more attention to the relation between nutrition and duodenum weight and duodenum function in further studies.

Quantitative feed restriction or meal-feeding of broiler chicks alter functional development of enzymes for protein digestion

1. Two experiments were performed on broiler chicks to determine the effect of either quantitative feed restriction (QFR) from 5 to 11 d of age or meal-feeding (MF) from d 5 to 17 on development of activity of enzymes associated with protein digestion. 2. Proteolytic activity of the proventriculus was reduced by QFR but unaffected by MF. 3. General proteolytic and carboxypeptidase A activities of the pancreas were reduced by QFR and MF. 4. Amino- and dipeptidase activities of the small intestine were increased by QFR. Dipeptidase activity was unaffected by MF. 5. Nitrogen retention of QFR chicks was lower immediately following feed restriction but not in the 2 weeks following return to ad libitum access to feed. 6. Feeding regimen alters functional development of the enzymes of protein digestion and may therefore influence growth rate of broilers.

Effect of early feed restriction on metabolic programming and compensatory growth in broiler chickens

The effect of early feed restriction on metabolic programming and compensatory growth was studied in broiler chickens. A total of 480 female 1-d-old broiler birds (Aconred) were randomly allocated to ad libitum and feed-restricted groups, each of which was replicated 6 times with 40 birds per replicate. Broilers were provided commercial diets. Feed-restricted broilers were deprived of feed for 4 h per day from 1 to 21 d of age. Effects of treatments were determined at 21 and 63 d of age. In feed-restricted birds at 21 d of age, BW, average daily gain and average daily feed intake, breast muscle (P < 0.01), carcass yield (P < 0.05), and abdominal fat (P < 0.05) were decreased. Ether extract content in breast muscle was increased (P < 0.01), whereas CP content was slightly decreased. Triiodothyronine (P < 0.01) and thyroxine (P < 0.05) were decreased in serum. Free fatty acid and very low density lipoprotein were slightly increased in serum, whereas triglyceride and glucose were decreased (P < 0.01). Activities of NADPH-generating enzymes in liver including malic dehydrogenase, isocitrate dehydrogenase, and glucose-6-phosphate remained unchanged in ad libitum birds, whereas hormone-sensitive lipase activity was increased (P < 0.01). In feed-restricted birds at 63 d of age, BW, average daily gain, average daily feed intake, carcass yield, breast muscle yield, and serum triiodothyronine and thyroxine remained as ad libitum birds, whereas abdominal fat yield was increased (P < 0.05). Ether extract content in breast muscle was decreased (P < 0.01), whereas CP content was increased (P < 0.05). Activities of NADPH-generating enzymes were significantly increased, except abdominal malic dehydrogenase and hormone-sensitive lipase activity was decreased (P < 0.01) in liver and abdominal fat. Lipoprotein lipase activity was increased (P < 0.05) in abdominal fat. In summary, feed restriction severely affected growth performance and lipid metabolism in broilers in the early period. Because there was no statistical difference among the final BW, near full compensatory growth was achieved. In addition, early feed restriction might have induced prolonged metabolic programming in chicks and led to adult obesity.

Effect of early feed restriction on myofibre types and expression of growth-related genes in the gastrocnemius muscle of crossbred broiler chickens

The purpose of this study was to investigate the immediate and long-term effects of early feed restriction (ER) on morphology and gene expression of lateral gastrocnemius muscle. Newly hatched crossbred broiler chickens were allocated into control and ER groups, the latter being free-fed on alternate days from hatch to 14 days of age (14 d), followed by ad libitum feeding as the control group until 63 d. The lateral gastrocnemius muscle was taken at 14 and 63 d, respectively for myofibre typing by both myosin ATPase staining and relative quantification of myosin heavy chain (MyHC) mRNA for slow-twitch (SM), red fast-twitch (FRM) and white fast-twitch (FWM) myofibres. The body weight and lateral gastrocnemius weight were significantly lower in the ER group, accompanied by significantly reduced serum triiodothyronine. The ER group exhibited significantly higher SM and FRM MyHC expression at 14 d, but lower SM expression at 63 d. Myosin ATPase staining revealed a similar pattern. The percentage of SM was higher at 14 d while lower at 63 d in the ER group. These morphological changes were accompanied by changes of mRNA expression for growth-related genes. The ER group expressed lower insulin-like growth factoar I (IGF-I) and higher IGF-I receptor (IGF-IR) at 14 d, yet significantly increased growth hormone receptor and IGF-IR mRNA at 63 d. These results indicate that ER may delay the slow to fast myofibre conversion as an immediate effect, but would result in a lower percentage of slow fibres owing to compensatory growth in the long term, which involves changes of mRNA expression for the growth-related genes in the muscle.

Effects of in ovo feeding of carbohydrates and beta-hydroxy-beta-methylbutyrate on the development of chicken intestine

Early development of the digestive tract is crucial for achieving maximal growth and development of chickens. Because the late-term embryo naturally consumes the amniotic fluids, insertion of a nutrient solution into the embryonic amniotic fluid [in ovo (IO) feeding] may enhance development. This study examined the effect of IO feeding on d 17.5 of incubation of carbohydrates (CHO) and beta-hydroxy-beta-methylbutyrate (HMB) on small intestinal development of chickens during the pre and posthatch periods. Results shows that 48 h post-IO feeding procedure all IO feeding treatments exhibited increased villus width and surface area compared with the control group. At d 3 posthatch the surface area of an average villi was increased by 45% for the HMB IO group and by 33% for the CHO and CHO+HMB IO groups compared with controls (noninjected fertile eggs). The activity of jejunal sucrase-isomaltase (SI) was higher (P < 0.05) 48 h after IO feeding in all the IO fed embryos, whereas at day of hatch and at d 3 the CHO+HMB IO group had the highest maltase activity (P < 0.05), which was approximately 50% greater than control embryos. These observations indicated that small intestines of IO fed hatchlings were functionally at a similar stage of development as a conventionally fed 2-d-old chick. Body weight of all IO fed hatchlings was greater than controls, and these differences (P < 0.05) were sustained until the end of the experiment (10 d). At d 10 chicks that were IO fed with CHO had BW that were 2.2% higher, whereas HMB and CHO+HMB IO fed chicks showed 5 to 6.2% BW increase, respectively, compared with controls. The current study shows that the administration of exogenous nutrients into the amnion enhanced intestinal development by increasing the size of the villi and by increasing the intestinal capacity to digest disaccharides. This advantage probably leads to higher BW in IO fed chicks.

Effect of Refeeding on Growth, Development, and Behavior of Undernourished Bank Swallow (Riparia Riparia) Nestlings

Nestlings of aerial insectivores adjust their energetics, behavior, and development of internal organs in response to food shortages and subsequent improvements in feeding conditions. Here, we present results of laboratory refeeding of Bank Swallow (Riparia riparia) nestlings, which were undernourished between 4 and 7 days of age. During a subsequent three-day-long refeeding, their body mass did not catch up with that of individuals continuously fed ad libitum. However, refed young managed to compensate for delayed growth of pectoral muscles, small intestines, and fully restored fat reserves. Their resting metabolic rates and body temperatures increased to values similar to those of nestlings fed ad libitum. In contrast, digestive activity of their guts (quantified as carrier-mediated intestinal brushborder uptake rate of L-proline) was reduced, as compared with the period of undernutrition. Likewise, high locomotor activity observed during food shortage was significantly reduced upon refeeding. Furthermore, differences in body mass between nest mates, which had earlier modulated both locomotor activity and physiological responses to food shortage, had no effect on mobility and physiology of refed nestlings. Our results indicate that even a short, three-day period of refeeding triggered conspicuous acceleration of growth and development of vital internal organs in previously undernourished nestlings. However, that was not accompanied by significant compensatory whole-body growth (defined as a period of above-normal rapid growth, relative to age).

Feeding regimen and enzyme supplementation to rye-based diets for broilers

A trial was conducted to study the influence of feeding regimen [ad libitum, (AL) vs. feed restriction, (FR)] and supplementation of the diet with a combination of xylanase and beta-glucanase on physiological parameters and performance of broilers fed rye-based diets. There were 4 dietary treatments arranged factorially with 2 feeding regimens (0 vs. 30% FR from 4 to 14 d), 2 enzyme doses (0 vs. 500 ppm), and an additional corn control diet. Each treatment was replicated 9 times from 4 to 25 d (15 chicks caged together) and 6 times from 25 to 46 d. From 4 to 46 d of age, FR did not affect weight gain and improved feed conversion of broilers (P < 0.05). Also, FR reduced the incidence of leg disorders, digesta viscosity, and pasted vents (P < 0.01) and increased relative weight of gizzard (P < 0.001). Enzyme supplementation (ES) improved average daily gain and feed conversion at all ages (P < 0.01), and the beneficial effects were greater for AL than for FR birds (P < 0.10). Also, ES reduced digesta viscosity (P < 0.001), relative weights of gizzard (P < 0.05) and crop (P < 0.01), and jejunum length (P < 0.05). Compared with feeding corn, feeding rye AL with or without ES impaired growth and feed conversion from 4 to 46 d (P < 0.01) and increased incidence of leg disorders (P < 0.05), viscosity of jejunum content (P < 0.01), and jejunum length (P < 0.05). We concluded that rye in feed impaired broiler performance and increased digesta viscosity and incidence of leg disorders and that FR and ES reduced the magnitude of the problem. The beneficial effects of ES on bird performance were more evident when birds were fed AL.

Vitamin A exerts its activity at the transcriptional level in the small intestine

THE AIM OF THIS STUDY

was to examine the effects of vitamin-A deficiency on the small intestinal morphology and on brush-border enzyme function and expression.

METHODS

Weanling male rats were fed a vitamin-A deficient (VAD), sufficient (VAS), or supplemented (VASUP) diet, or were pair-fed (PF) with the VAD rats. Average food intakes were not different among the groups.

RESULTS

From days 35 to 42, the body weight of VAD rats began to plateau, whereas the other groups, including the PF rats, continued to gain weight. At days 48 to 51, the final mean body weight of VAD rats was significantly lower than that of PF, VAS and VASUP rats (P < 0.05). Serum and liver retinol levels were lower in VAD rats (by 85 % and 99%, respectively) and higher in the VASUP group (by 126 % and 160%, respectively) compared to the VAS group (P < 0.01). Histological examination of the jejunum revealed that in VAD rats the villi were shorter and thicker and there was an elevation in crypt depth relative to the other treatment groups. Infiltration of inflammatory cells was also observed in the jejunum of most of the VAD rats, but not in rats from other groups. Biochemical assays revealed that in VAD rats, alkaline phosphatase (ALP) and sucrase-isomaltase (SI) activities are significantly decreased in the jejunum, compared to PF, VAS and VASUP groups (P < 0.01). ALP activity was decreased in the duodenum of VAD rats as well. By comparison, amino-peptidase (AP) activity per mg protein in the jejunum and ileum of VAD rats was significantly increased compared to VAS and VASUP rats (P < 0.01), but was not different from PF rats. In all of the small intestinal sections, mRNA expression of all three brush-border enzymes relative to beta-actin were significantly lower in VAD rats than in the other treatment groups. SI was similarly expressed in all of the small intestinal organs, whereas AP and ALP expression varied.

CONCLUSIONS

Our results suggest that vitamin-A deficiency modifies the maturation and differentiation processes of the small intestinal mucosa at the transcriptional and post-transcriptional levels respectively. This in turn may be one explanation for the alteration or elimination of nutrient digestion and absorption during VAD.

Efeito da restrição alimentar inicial e da temperatura ambiente sobre o desenvolvimento de vísceras e ganho compensatório em frangos de corte

O presente trabalho teve como objetivo estudar o efeito da restrição alimentar quantitativa inicial e da temperatura ambiente sobre o desenvolvimento de vísceras e ganho compensatório em frangos de corte. Foram utilizados 540 frangos machos, em um delineamento inteiramente ao acaso, segundo esquema fatorial 2 x 3, com os fatores programa alimentar (ad libitum e restrito do 7° ao 14° dia de idade) e temperatura ambiente (quente, termoneutra e fria). A restrição alimentar não afetou o peso relativo do fígado e do coração, mas reduziu significativamente o peso e o comprimento dos intestinos ao final do período de restrição (14 dias de idade). Não foi observado efeito significativo da restrição alimentar sobre o desenvolvimento das vísceras estudadas aos 42 dias de idade. Peso vivo, ganho de peso e consumo de ração dos frangos com restrição alimentar foram significativamente menores aos 28 dias de idade, porém não foram observadas diferenças entre essas variáveis aos 42 dias de idade, demonstrando ganho compensatório durante o período de realimentação. O peso relativo das vísceras não foi afetado pela temperatura de criação aos 42 dias de idade, exceto o coração. Consumo de ração, ganho de peso e peso vivo aos 42 dias de idade foram significativamente menores nas aves mantidas em altas temperaturas.