The learning ability and memory retention of broiler breeders: 2 transgenerational effects of reduced balanced protein diet on reward-based learning

The effect of reduced balanced protein (RP) diet in the F0 and F1 generation of broiler breeders on the learning ability and memory retention of the F2 generation was investigated by means of a reward v. no reward discrimination T-maze test. There were two treatments for the F0 generation: control (C) group, reared on standard commercial diets, and reduced balanced protein (RP) group, fed with RP diets (25% reduction in CP and amino acids). The female F0-progeny of each treatment was again separated into the two dietary treatments, resulting in four treatments for the F1 generation: C/C, C/RP, RP/C and RP/RP (breeder feed in F0/F1 generation). The RP diets fed breeders received on average 10% more feed than C diets fed breeders to achieve a similar target BW. The F2 generation was composed of four treatments coming from the female F1-progeny of the four treatments and were all fed with C diet (namely C/C/C, C/RP/C, RP/C/C and RP/RP/C). All four F2 generation groups were able to complete the T-maze learning test with a slight difference in success rate but a significant difference within groups was observed regarding the time needed to complete the test. In general, the RP/RP/C group needed more time for completing the test compared with the other three groups and the shortest time was recorded for the RP/C/C group. At similar ages, breeders with early learning experience spent significantly less time in completing the test compared with unexperienced breeders. Long-term memory retention was observed in all four groups whereas the learning ability in solving the test decreased with age. It took longer for the breeders to complete the test at older ages. In conclusion, under our experimental conditions, the RP dietary treatment in previous generations had no influence on the T-maze learning ability and memory retention of broiler breeders of the third generation, although it might have effects on the working performance in the T-maze learning test of F2 generation breeders.     

The effects of a reduced balanced protein diet on litter moisture,pododermatitis and feather condition of female broiler breeders over three generations

Protein content reduction in broiler breeder diets has been increasingly investigated. However, broiler breeders reared on low protein diets are characterized by a deterioration of the feather condition. Furthermore, polydipsia induced by controlled feed intake increases litter moisture and as a consequence pododermatitis. This project aimed to study the litter moisture, pododermatitis and feather condition of breeders fed with a 25% reduced balanced protein (RP) diet during the rearing and laying period over three successive generations. The experiment started with two treatments for the F0 generation: control (C) group fed with standard C diets and RP group fed with RP diets. The female F0-progeny of each treatment was divided into the two dietary treatments as well, resulting in four treatments for the F1 generation: C/C, C/RP, RP/C and RP/RP (breeder feed in F0/F1 generation). The RP diet fed breeders received on average 10% more feed than C diet fed breeders to achieve the same target BW. The female F1-progeny of each treatment were all fed with C diets which resulted in four treatments for the F2 generation: C/C/C, C/RP/C, RP/C/C and RP/RP/C (breeder feed in F0/F1/F2 generation). Litter moisture, footpad and hock dermatitis were recorded at regular intervals throughout the experimental period in all three generations. For the F0 and F1 generation, the pens of breeders receiving C diets had significantly higher litter moisture than the RP diets fed groups (P<0.05), resulting in an elevated footpad dermatitis occurrence (FDO) (P<0.05). No difference was found in the F2 generation. The feather condition was scored during the laying period for each generation. F0 and F1 breeders reared on the RP diets had poorer feather condition than those receiving the C diets (P<0.05). The C/RP breeders had a significantly poorer feather condition than RP/RP breeders (P<0.05). For the F2 generation, RP/RP/C breeders had a significantly better feather condition compared with the other three groups (P<0.05). The RP/C/C breeders were significantly better feathered than C/C/C breeders (P<0.05). In conclusion, providing RP diets to broiler breeders improved litter condition and hence reduced FDO whereas impaired feather condition. Furthermore, positive transgenerational effects of the maternal RP diets on the feather condition may be inferred, hence potentially altering the welfare status.     

Effects of dark brooders and overhangs on free-range use and behaviour of slow-growing broilers

Broiler chickens often make limited use of the free-range area. Range use is influenced by type of shelter available. Range use may possibly be improved by a more gradual transition from the house to the range and by using dark brooders (secluded warm, dark areas in the home pen) that mimic aspects of a broody hen and possibly reduce fearfulness. The aim of this study was to assess effects of dark brooders on fearfulness, free-range use and behaviour later in life. Another aim was to test the chickens’ preference for shelter type and the effects of overhangs outside of the pop holes to provide a gradual transition to the range. Three production rounds, each with 440 Sasso broiler chickens (110/group), were completed. Chicks were housed indoors from days 0 to 25; per round, two groups had access to a dark brooder, whereas the other two groups had conventional IR lamps. Fearfulness was assessed by the open field (OF) and tonic immobility (TI) tests on days 22 to 24 on 25 chicks/group per round. Birds were then moved to four mobile houses from which they could access both grassland with artificial shelter (AS) and short rotation coppice (SRC). Two of the houses had overhangs extending from the pop holes; these were switched between the four houses weekly. Free-range use and behaviour were observed three times daily from Monday to Friday. Dark brooders did not affect results from the OF or TI test, except for jumps in the OF test which tended to occur less often in brooded chicks. Neither dark brooders (34.9% without v. 31.7% with brooder) nor overhangs (32.5% without v. 34.1% with overhangs) influenced the percentage of chickens outside. Chickens showed a clear preference for SRC, range use increased over time in SRC, and more birds ranged farther from the house in SRC. Behaviours of chickens observed outside were mainly influenced by shelter type, age of the birds and distance from the house. Locomotion tended to occur more in the presence of overhangs. Overall, these results could not confirm the hypothesis that dark brooders would decrease fearfulness and thereby increase free-range use. Overhangs also did not improve free-range use, and neither brooders nor overhangs had considerable impact on behaviour of chickens outside. Chickens clearly preferred dense natural vegetation over AS and ranged farther in it, indicating that this type of shelter is more suitable for slow-growing free-range broilers.     

The effect of alternative feeding strategies on the feeding motivation of broiler breeder pullets

Due to genetic selection for fast growth and high breast meat yield, commercial strains of broiler chickens and broiler breeders are predisposed to high feed intake; however, feeding broiler breeders ad libitum impairs their health and reproductive performance. Broiler breeders are feed-restricted throughout rearing to maintain health and performance, yet feed restriction results in hunger, feeding frustration and lack of satiety. The objective of this study was to examine the effect of alternative feeding strategies, including feed additives (separately or combined) and a fixed non-daily feeding schedule, on the feeding motivation and welfare of broiler breeders during rearing. At 3 weeks of age, 180 Ross 308 breeder pullets were allocated to 90 cages and fed with one of five isocaloric treatments: (1) daily control diet (control), (2) daily calcium propionate diet (CaP), (3) daily soybean hull diet (SBH), (4) daily alternative diet (alternative: CaP + SBH) and (5) 4/3 control diet (four on-feed days and three non-consecutive off-feed days per week). The CaP diet included calcium propionate at 1.4% from 3 to 6 weeks of age, and at 3.2% from 7 to 12 weeks of age, and the SBH diet contained soybean hulls included at 40%. The alternative diet included both soybean hulls and calcium propionate at the same inclusion rate as the SBH and CaP diets, respectively. Pullets were weighed and scored for feather coverage every week. A feed intake test was conducted at 3, 4, 8, 10 and 11 weeks of age for 10 min during on- and off-feed days. At 12 weeks of age, feather samples were analysed for fault bars. Data were analysed using linear mixed regression models, with cage nested in the models and age as a repeated measure. At 4 weeks of age, pullets fed soybean hull-enriched diets (SBH and alternative diets) and those on the 4/3 schedule had lower feed intake than control pullets (P = 0.02). Feathers from pullets fed the SBH diet had fewer fault bars than those fed the CaP diet (P = 0.04). The results indicated that the inclusion of soybean hulls (alone or combined with calcium propionate) and a 4/3 feeding schedule can reduce feeding motivation of broiler breeders during early rearing.     

Effects of shelter type,early environmental enrichment and weather conditions on free-range behaviour of slow-growing broiler chickens

Free-range use by broiler chickens is often limited, whereas better use of the free-range area could benefit animal welfare. Use of free-range areas could be stimulated by more appropriate shelter or environmental enrichment (by decreasing birds’ fearfulness). This study aimed to assess the effects of shelter type, early environmental enrichment and weather conditions on free-range use. Three production rounds with 440 slow-growing broiler chickens (Sasso T451) were carried out. Birds were housed indoors in four groups (two with males, two with females) from days 0 to 25, during which two of the groups received environmental enrichment. At day 23 birds’ fearfulness was assessed with a tonic immobility (TI) test (n=100). At day 25 all birds were moved (in mixed-sex groups) to mobile houses, and provided with free-range access from day 28 onwards. Each group could access a range consisting for 50% of grassland with 21 artificial shelters (ASs, wooden A-frames) and for 50% of short rotation coppice (SRC) with willow (dense vegetation). Free-range use was recorded by live observations at 0900, 1300 and 1700 h for 15 to 21 days between days 28 and 63. For each bird observed outside the shelter type (AS or SRC), distance from the house (0 to 2, 2 to 5, >5 m) and its behaviour (only rounds 2 and 3) were recorded. Weather conditions were recorded by four weather stations. On average, 27.1% of the birds were observed outside at any given moment of observation. Early environmental enrichment did not decrease fearfulness as measured by the TI test. It only had a minor effect on the percentage of birds outside (0.4% more birds outside). At all distances from the house, SRC was preferred over AS. In AS, areas closer to the house were preferred over farther ones, in SRC this was less pronounced. Free-range use increased with age and temperature and decreased with wind speed. In AS, rainfall and decreasing solar radiation were related to finding more birds outside, whereas the opposite was true in SRC. Behaviour of the birds depended on shelter type, distance from the house, early environmental enrichment, time of day and age. Chickens ranged more and farther in SRC, possibly because this provided a greater sense of safety because of the amount of cover and/or better protection against adverse weather conditions. These results indicate that SRC with willow is a more appropriate shelter for slow-growing broiler chickens than A-frames.     

Gregarious nesting in relation to floor eggs in broiler breeders

Gregarious nesting has often been observed in laying hens, where hens prefer to visit a nest already occupied by other hens over empty nests. This may result in overcrowding of the nests which is considered a welfare issue and, moreover, can increase the economic issue of floor eggs. This study aimed to describe gregarious nesting and spatial behavior in broiler breeders and how this relates to genetic background, fearfulness and mating behavior. Five commercially available genetic lines of broiler breeders were housed in 21 pens of 550 females and 50 males (six pens for lines 1 and 2, five pens for line 3 and two pens for lines 4 and 5) during the ages 20–60 weeks. Every 10 weeks, the plumage condition and wounds were assessed of 50 random hens per pen. Avoidance distance and novel object tests were performed to assess fearfulness at four time points. Distribution of eggs over nests was observed for 6 weeks at the onset of egg production at 26 weeks of age, and use of space was recorded at four time points, while (floor) egg production was noted daily per pen. We found differences between genetic lines over time in plumage condition and prevalence of wounds. Fear of humans was highest at the earliest age tested and did not correlate with general fearfulness as assessed by the novel object test. The distribution of eggs over nests was related to genetic background and was more uneven at the earliest age compared to later ages, and a more uneven distribution was correlated with an increased percentage of floor eggs. Distribution of birds over the litter area differed between the genetic lines, and less use of the litter area was correlated with an increased fear of humans and presence of wounds, suggesting an association with aggressive mating behavior. This difference in distribution of the birds could also explain the correlation between increased presence of wounds and decreased percentage of floor eggs. It is concluded that broiler breeders do show gregarious nesting, which is affected by genetic background. Both increased gregarious nesting and wounds are related to increased floor egg percentage, which should be studied further in broiler breeder research. Genetic selection for even use of the available nests and of the litter and slatted area would therefore support both broiler breeder welfare and performance.     

Black soldier fly as dietary protein source for broiler quails: apparent digestibility,excreta microbial load,feed choice,performance, carcass and meat traits

In order to expand with validated scientific data the limited knowledge regarding the potential application of insects as innovative feed ingredients for poultry, the present study tested a partial substitution of soya bean meal and soya bean oil with defatted black soldier fly (Hermetia illucens) larvae meal (H) in the diet for growing broiler quails (Coturnix coturnix japonica) on growth performance, mortality, nutrients apparent digestibility, microbiological composition of excreta, feed choice, carcass and meat traits. With this purpose, a total of 450 10-day-old birds were allocated to 15 cages (30 birds/cage) and received three dietary treatments: a Control diet (C) and two diets (H1 and H2) corresponding to 10% and 15% H inclusion levels, respectively (H substituted 28.4% soya bean oil and 16.1% soya bean meal for H1, and 100% soya bean oil and 24.8% soya bean meal for H2, respectively). At 28 days of age, quails were slaughtered, carcasses were weighed, breast muscles were then excised from 50 quails/treatment, weighed, and ultimate pH (pHu) and L*, a*, b* colour values were measured. Breast muscles were then cooked to assess cooking loss and meat toughness. For the digestibility trial, a total of 15 28-day-old quails were assigned to the three feeding groups. The excreta samples were subjected to chemical and microbiological analysis. The same 15 quails were then simultaneously provided with C and H2 diets for a 10-day feed choice trial. Productive performance, mortality and carcass traits were in line with commercial standards and similar in all experimental groups. With the exception of ether extract digestibility, which was lower in H1 group compared with C and H2 (P=0.0001), apparent digestibility of dry matter, CP, starch and energy did not differ among treatments. Microbial composition of excreta was also comparable among the three groups. Feed choice trial showed that quails did not express a preference toward C or H2 diets. Breast meat weight and yield did not differ among C, H1 and H2 quails. Differently, the inclusion of H meal reduced meat pHu compared with C. In conclusion, this study demonstrated that H. illucens larvae meal can partially replace conventional soya bean meal and soya bean oil in the diet for growing broiler quails, thus confirming to be a promising insect protein source for the feed industry. Further research to assess the impact of H meal on intestinal morphology as well as on meat quality and sensory profile would be of utmost importance.     

Inclusion of sorghum,millet and cottonseed meal in broiler diets: a meta-analysis of effects on performance

A meta-analysis was conducted (i) to evaluate broiler response to partial or total substitution of corn by sorghum and millet and (ii) to determine the effect of soybean meal replacement by cottonseed meal in broiler diet. The database included 190 treatments from 29 experiments published from 1990 to 2013. Bird responses to an experimental diet were calculated relative to the control (Experimental−Control), and were submitted to mixed-effect models. Results showed that diets containing millet led to similar performance as the corn-based ones for all parameters, whereas sorghum-based diets decreased growth performance. No major effect of the level of substitution was observed with millet or cottonseed meal. No effect of the level of substitution of sorghum on feed intake was found; however, growth performance decreased when the level of substitution of corn by sorghum increased. Cottonseed meal was substituted to soybean meal up to 40% and found to increase feed intake while reducing growth performance. Young birds were not more sensitive to these ingredients than older birds since there was no negative effect of these ingredients on performance in the starter phase. Results obtained for sorghum pointed out the necessity to find technological improvements that will increase the utilization of these feedstuffs in broiler diet. An additional work is scheduled to validate these statistical results in vivo and to evaluate the interactions induced with the simultaneous inclusions of sorghum, millet and cottonseed meal in broiler feeding.     

Effects of Zinc Glycinate on Productive and Reproductive Performance,Zinc Concentration and Antioxidant Status in Broiler Breeders

An experiment was conducted to investigate the effects of zinc glycinate (Zn-Gly) supplementation as an alternative for zinc sulphate (ZnSO₄) on productive and reproductive performance, zinc (Zn) concentration and antioxidant status in broiler breeders. Six hundred 39-week-old Lingnan Yellow broiler breeders were randomly assigned to 6 groups consisting of 4 replicates with 25 birds each. Breeders were fed a basal diet (control group, 24 mg Zn/kg diet), basal diet supplemented with 80 mg Zn/kg diet from ZnSO₄ or basal diet supplemented with 20, 40, 60 and 80 mg Zn/kg diet from Zn-Gly. The experiment lasted for 8 weeks after a 4-week pre-test with the basal diet, respectively. Results showed that Zn supplementation, regardless of sources, improved (P?<?0.05) the feed conversion ratio (kilogram of feed/kilogram of egg) and decreased broken egg rate, and elevated (P?<?0.05) the qualified chick rate. Compared with the ZnSO₄ group, the 80 mg Zn/kg Zn-Gly group significantly increased (P?<?0.05) average egg weight, fertility, hatchability and qualified chick rate, whereas it decreased (P?<?0.05) broken egg rate. The Zn concentrations in liver and muscle were significantly higher (P?<?0.05) in 80 mg Zn/kg Zn-Gly group than that in ZnSO₄ group. Compared with ZnSO₄ group, 80 mg Zn/kg Zn-Gly group significantly elevated (P?<?0.05) the mRNA abundances of metallothionein (MT) and copper-zinc superoxide (Cu-Zn SOD), as well as the Cu-Zn SOD activity and MT concentration in liver. Moreover, the 80 mg Zn/kg Zn-Gly group had higher (P?<?0.05) serum T-SOD and Cu-Zn SOD activities than that in the ZnSO₄ group. This study indicated that supplementation of Zn in basal diet improved productive and reproductive performance, Zn concentration and antioxidant status in broiler breeders, and the 80 mg Zn/kg from Zn-Gly was the optimum choice for broiler breeders compared with other levels of Zn from Zn-Gly and 80 mg/kg Zn from ZnSO₄.     

Clostridium perfringens challenge and dietary fat type affect broiler chicken performance and fermentation in the gastrointestinal tract

The aim of the present work was to examine how different fats commonly used in the feed industry affect broiler performance, nutrient digestibility and microbial fermentation in the gastrointestinal tract of broiler chickens challenged with virulent Clostridium perfringens strains. Two experiments were carried out, each including 480-day-old male broilers (Ross 308), which were randomly distributed to eight experimental groups using six replicate pens per treatment and 10 birds per pen. In Experiment 1, birds were fed diets containing soybean oil, palm kernel fatty acid distillers, rendered pork fat and lard. In Experiment 2, birds were fed diets containing rapeseed oil, coconut oil, beef tallow and palm oil. In both experiments, the birds were either not challenged or challenged with a mixture of three C. perfringens type A strains. Irrespective of the fat type present in the diet, C. perfringens did not affect broiler chicken body weight gain (BWG) and mortality in either of the two experiments. The BWG was affected by dietary fat type in both experiments, indicating that the fatty acid composition of the fat source affects broiler growth performance. In particular, the inclusion of animal fats tended to improve final BW to a greater extent compared with the inclusion of unsaturated vegetable oils. In Experiment 2, irrespective of the dietary fat type present in the diet, C. perfringens challenge significantly impaired feed conversion ratio in the period from 14 to 28 days (1.63 v. 1.69) and at 42 days (1.65 v. 1.68). In both experiments apparent metabolizable energy values were affected by dietary fat type. Irrespective of the fat type present in the diet, C. perfringens challenge decreased the digesta pH in the crop and ileum, but had no effect in cecal contents. Moreover, in Experiment 1, total organic acid concentration in the ileum was two to three times lower on soybean oil diets as compared with other treatments, indicating that C. perfringens as well as dietary fat type significantly affects microbiota activity in the broiler chicken gastrointestinal tract.     

Nutritive value and anthelmintic effect of sainfoin pellets fed to experimentally infected growing rabbits

Alternative strategies to synthetic chemical drugs are needed in livestock and are a key issue in organic farming today. This study aimed at examining the potentialities of sainfoin, a legume rich in condensed tannins, as a nutraceutical that combines nutritive and antiparasitic effects in rabbits. To test the effect of infection with a helminth (I: infected groups; NI: not infected groups) and the effect of substituting 40% of the alfalfa in a control diet (C) with sainfoin (diet S), four groups of 16 weaned rabbits were arranged according to a 2×2 bifactorial design. The sainfoin diet differed from the control by its tannin concentration (1.8% v. 1.0% tannic acid equivalent) and its ADL concentration (84 v. 43 g/kg). For each diet, 16 rabbits were infected with 2125 third-stage larvae of Trichostrongylus colubriformis. Growth, feed intake, feed conversion ratio and nematode faecal egg counts (FECs) were controlled for 6 weeks. A digestibility trial was performed. After necropsy, adult worms and eggs in utero per female were counted and egg-hatching rate calculated. Growth tended to be lower for S groups than for C groups (38.2 v. 39.5 g/day; P=0.06). Feed intake was higher for S groups compared with C groups (+5.2 g dry matter/day; P<0.01), as was the feed conversion ratio (3.2 v. 2.9; P<0.001), probably in relation to the dietary ADL level. Protein digestibility was reduced in S groups compared with C groups (−6.0 points; P<0.001), probably associated with the effect of the tannin concentration. Digestibility of hemicelluloses was reduced in infected rabbits compared with non-infected ones (−5 points; P=0.01). Using the substitution method, the digestible energy of dehydrated sainfoin pellets used as raw material was calculated at 11.12 MJ/kg and digestible proteins at 110 g/kg. The infection did not produce any clinical signs of digestive disorders. No differences were observed according to the diet, neither in the number of adult worms (972; P=0.50), the number of eggs in utero per female (14; P=0.95), nor FEC (400 eggs/g; P=0.57). In contrast, the rate of faecal egg hatching in the S group tended to be lower than in the control (58.3% v. 85.2%; P=0.08). In conclusion, sainfoin seems to fit nutritive requirements for rabbits, supplies a large quantity of fibre and particularly lignins, and limits the development of nematode eggs in faeces.     

Proportion of insoluble fibre in the diet affects behaviour and hunger in broiler breeders growing at similar rates

With a view to alleviate the feeling of hunger in broiler breeders, different types of fibre sources were used in high-fibre diets to increase feed quantity while limiting growth to industry recommended levels. Using scatter feeding, three diets (C1: commercial control diet, 1 × fibre content, 80% insoluble fibre (ISF); H2: 2 × fibre content, 89% ISF; and L2: 2 × fibre content, 71% ISF) were each fed to 10 groups of 16 broiler breeder chickens. Similar growth rates were obtained on different quantities of food with all birds reaching commercial target weight at 15 weeks of age. In a hunger test, birds fed C1 ate significantly faster and showed a higher compensatory feed intake than birds on diets H2 and L2, indicating that the two high-fibre diets did reduce the level of hunger experienced by the birds. Behavioural observations carried out at 14 weeks of age showed high levels of tail pecking in birds fed C1 and almost none in birds fed L2, whereas birds fed H2 were intermediate. Stereotypic pecking at fixtures was seen twice as frequently in birds fed C1. Birds on diet L2 displayed behavioural signs indicative of discomfort, and the high water usage on this diet created problems with litter quality. Birds on diet H2 continued to show foraging behaviour throughout the day, and were more frequently engaged in dust bathing and other comfort behaviour. This experiment indicates that high-fibre diets can alleviate the feeling of hunger currently experienced by broiler breeders, and a high ratio of ISF may improve the well-being of the birds.     

Working for food under conditions of varying motivation in broilers

Broiler chickens, Gallus gallus domesticus, have been selected for rapid weight gain and appear to be continously hungry. If this is so, then energy that broilers invest in obtaining food should be insensitive to their level of feed restriction. We tested this hypothesis by measuring the maximum price (i.e. maximum number of key pecks) broilers with different body weights would pay for a food reward under conditions of varying feed restriction. Two groups of 20 broilers were fed on 50 or 75% of the amount of feed a broiler would eat when fed ad libitum. Broilers were able to learn an operant task and were willing to work for food. Birds of the 50%-group paid a higher maximum price for a food reward and responded more quickly to food presentation than the birds of the 75%-group in the first test week and showed a nonsignificant tendency to pay a higher price and to respond more quickly in the second test week. Different levels of long-term feed restriction had an influence on their body weight and on their motivation to work for food. No short-term effect of changing feed restriction was found. Birds showed frustration behaviour after the last food reward had been obtained, indicating that they were still hungry. The results indicate that broilers are still sensitive to different levels of feed restriction and that they can balance their investments and profits to a certain extent.     

Effect of Dietary Vitamin A on Reproductive Performance and Immune Response of Broiler Breeders

The effects of dietary vitamin A supplementation on reproductive performance, liver function, fat-soluble vitamin retention, and immune response were studied in laying broiler breeders. In the first phase of the experiment, 1,120 Ross-308 broiler breeder hens were fed a diet of corn and soybean meal supplemented with 5,000 to 35,000 IU/kg vitamin A (retinyl acetate) for 20 weeks. In the second phase, 384 Ross-308 broiler breeder hens were fed the same diet supplemented with 5,000 to 135,000 IU/kg vitamin A (retinyl acetate) for 24 weeks. The hens'' reproductive performance, the concentrations of vitamins A and E in liver and egg yolk, liver function, mRNA expression of vitamin D receptor in duodenal mucosa, antibody titers against Newcastle disease virus vaccine, and T-cell proliferation responses were evaluated. Supplementation of vitamin A at levels up to and including 35,000 IU/kg did not affect reproductive performance and quadratically affected antibody titer to Newcastle disease virus vaccine (p<0.05). Dietary addition of vitamin A linearly increased vitamin A concentration in liver and yolk and linearly decreased α-, γ-, and total tocopherol concentration in yolk (p<0.01) and α-tocopherol in liver (p<0.05). Supplementation of vitamin A at doses of 45,000 IU/kg and above significantly decreased egg weight, yolk color, eggshell thickness and strength, and reproductive performance. Dietary vitamin A significantly increased mRNA expression of vitamin D receptor in duodenal mucosa (p<0.05), increased aspartate amino transferase activity, and decreased total bilirubin concentration in serum. Supplementation of vitamin A at 135,000 IU/kg decreased the proliferation of peripheral blood lymphocytes (p<0.05). Therefore, the maximum tolerable dose of vitamin A for broiler breeders appears to be 35,000 IU/kg, as excessive supplementation has been shown to impair liver function, reproductive performance, and immune response.     

Insights on the Host Stress,Fear and Growth Responses to the Deoxynivalenol Feed Contaminant in Broiler Chickens

Mycotoxins pose an important danger to human and animal health. Poultry feeds are frequently contaminated with deoxynivalenol (DON) mycotoxin. It is thus of great importance to evaluate the effects of DON on the welfare related parameters in poultry industry. In the present study, the effects of contamination of broiler diet with 10 mg DON/kg feed on plasma corticosterone and heterophil to lymphocyte (H/L) ratio as indicators of stress, tonic immobility duration as an index for fear response and growth performance of broiler chickens were studied. In addition, the effect of a microbial feed additive either alone or in combination with DON contamination on these different aspects was also evaluated. The results showed that DON feeding significantly affected the welfare related parameters of broiler chickens. The feeding of DON contaminated diet resulted in an elevation of plasma corticosterone, higher H/L ratio and increased the fear levels as indicated by longer duration of tonic immobility reaction. Furthermore, DON reduced the body weight and body weight gain during the starter phase definitely at the second and third week. However, during grower phase, feeding of DON decreased the body weight at the fourth week and reduced the body gain at the fifth week. Addition of the microbial feed additive, a commercial antidote for DON mycotoxin, was able to overcome DON effects on stress index (H/L ratio), fearfulness and growth parameters of broilers. In conclusion, we showed for the first time that the DON feeding increased the underlying fearfulness and physiological stress responses of broilers and resulted in a reduction in the welfare status as indicated by higher plasma corticosterone, higher H/L ratio and higher fearfulness. Additionally, feeding the microbial feed additive was effective in reducing the adverse effects of DON on the bird''s welfare and can improve the performance of broiler chickens.     

Measuring Motivation for Appetitive Behaviour: Food-Restricted Broiler Breeder Chickens Cross a Water Barrier to Forage in an Area of Wood Shavings without Food

Broiler breeders (parents of meat chickens) are selected for fast growth and become obese if fed ad libitum. To avoid this and maintain good health and reproductive ability, they are feed restricted to about 1/3 of what they would eat ad libitum. As a result, they experience chronic hunger and exhibit abnormal behaviour patterns that may indicate stress and frustration. One approach to measuring hunger is to observe how much birds will work, such as pecking a key, for access to more or different types of food. However, the sight, smell, and feedback from consumption of the feed reward changes the context and may artificially raise feeding motivation. To avoid this, we tested broiler breeders in an apparatus in which they could work for access to a wooden platform covered in wood shavings by crossing a water runway which increased in length and depth in 8 successive tests. In the wood shavings area, they could perform exploratory and foraging behaviour (the appetitive phase of feeding) but were never rewarded with feed. Sixty birds were divided into three feed quantity treatments: commercial restriction (R), and twice (2R) or three times (3R) this amount. Overall, birds fed R worked harder to reach the wood shavings area (reached it in a larger number of tests) than 2R and 3R birds (P<0.001). More restricted birds took less time to reach the area (P<0.001, R<2R<3R) and spent more time foraging while there (P<0.001, R>2R>3R). This indicates that restricted-fed birds were hungry and willing to work for the opportunity to forage even though food was never provided, suggesting that their motivation to perform the appetitive component of feeding behaviour (foraging/food searching) was sufficient to sustain their response. Thus food restriction in broiler breeders is a welfare concern. However these methods could be used to test alternative feeding regimes to attempt to find ways of alleviating hunger while still maintaining healthy growth and reproduction in these birds.     

初步探讨鸟嘌呤核苷、姜黄素对AD双转基因小鼠学习记忆的影响

目的通过Morris水迷宫检测学习记忆和记忆保持能力,判断鸟嘌呤核苷、姜黄素对4月龄APPswe/PS1dE9双转基因小鼠认知功能的影响。方法将3月龄APPswe/PS1dE9双转基因小鼠随机分为模型组、盐酸多奈哌齐组0.92 mg/(kg·d)、鸟嘌呤核苷组20 mg/(kg·d)、姜黄素组200 mg/(kg·d)、姜黄素200 mg/(kg·d)和鸟嘌呤核苷组20 mg/(kg·d),每组12只;并以同月龄野生型C57/BL6J小鼠作对照。每天给药1次,连续给药1个月。应用Morris水迷宫进行行为学检测。结果鸟嘌呤核苷、姜黄素对空间探索、定位航行障碍有改善作用,尤其以姜黄素组明显。结论鸟嘌呤核苷、姜黄素能改善APPswe/PS1dE9双转基因小鼠的早期出现的认知障碍。     

Relationships between range access as monitored by radio frequency identification technology,fearfulness, and plumage damage in free-range laying hens

Severe feather-pecking (SFP), a particularly injurious behaviour in laying hens (Gallus gallus domesticus), is thought to be negatively correlated with range use in free-range systems. In turn, range use is thought to be inversely associated with fearfulness, where fearful birds may be less likely to venture outside. However, very few experiments have investigated the proposed association between range use and fearfulness. This experiment investigated associations between range use (time spent outside), fearfulness, plumage damage, and BW. Two pens of 50 ISA Brown laying hens (n=100) were fitted with radio frequency identification (RFID) transponders (contained within silicone leg rings) at 26 weeks of age. Data were then collected over 13 days. A total of 95% of birds accessed the outdoor run more than once per day. Birds spent an average duration of 6.1 h outside each day over 11 visits per bird per day (51.5 min per visit). The top 15 and bottom 15 range users (n=30), as determined by the total time spent on the range over 13 days, were selected for study. These birds were tonic immobility (TI) tested at the end of the trial and were feather-scored and weighed after TI testing. Birds with longer TI durations spent less time outside (P=0.01). Plumage damage was not associated with range use (P=0.68). The small group sizes used in this experiment may have been conducive to the high numbers of birds utilising the outdoor range area. The RFID technology collected a large amount of data on range access in the tagged birds, and provides a potential means for quantitatively assessing range access in laying hens. The present findings indicate a negative association between fearfulness and range use. However, the proposed negative association between plumage damage and range use was not supported. The relationships between range use, fearfulness, and SFP warrant further research.     

Beneficial nutraceutical modulation of cerebral erythropoietin expression and oxidative stress: an experimental study

The main object of this study is to examine the effect of Klamin?, a nutraceutical containing phenylethylamine, phycocyanins, mycosporine-like aminoacids and aphanizomenon flos aquae-phytochrome on the learning and memory ability, the oxidative status and cerebral erythropoietin and its receptor EPO/EPOR system in prematurely senescent (PS) mice. A total of 28 PS mice, selected according to a prior T-maze test, and 26 non-prematurely senescent mice (NPS) mice were chosen. PS animals were divided into 3 groups and followed for 4 weeks: A) normal chow diet; B) added with Klamin? at 20 mg/kg/day (low dose); C) added with Klamin? at 100mg/kg/day (high dose). A further group of NPS mice given either normal food (group D) or high dose Klamin? (group E) was also considered. The behavioral procedures of spatial learning ability (Morris test) showed that PS mice had significantly longer learning time as compared to their NPS counterpart (p<0.01), but this effect was prevented especially in mice supplemented with high-dose Klamin? (p<0.05) which improved performances in NPS mice (p<0.05). High-dose Klamin? supplementation restored the depleted total thiol concentration in the brain observed in PS mice while normalizing their increased malonildialdehyde level (p<0.05). Moreover, the high-dosage only caused a significant upregulation of EPO/EPOR system both in PS and in NPS animals (p<0.05). Taken together, these data suggest that this specific alga Klamath extract has considerable antioxidant and adaptogenic properties, also through a stimulatory effect of cerebral EPO/EPO system.     

Real-Time Quantitative PCR Measurement of Ileal Lactobacillus salivarius Populations from Broiler Chickens To Determine the Influence of Farming Practices

A real-time quantitative PCR assay targeting a 16S-23S intergenic spacer region sequence was devised to measure the sizes of populations of Lactobacillus salivarius present in ileal digesta collected from broiler chickens. This species has been associated with deconjugation of bile salts in the small bowel and reduced broiler productivity. The assay was tested as a means of monitoring the sizes of L. salivarius populations from broilers fed diets with different compositions, maintained at different stocking densities, or given the antimicrobial drugs bacitracin and monensin in the feed. Stocking densities did not influence the numbers of L. salivarius cells in the ileum. A diet containing meat and bone meal reduced the size of the L. salivarius population relative to that of chickens given the control diet, as did administration of bacitracin and monensin in the feed. These changes in the target bacterial population were associated with improved broiler weight gain.