Influence of nest seclusion and nesting material on pre-laying behaviour of laying hens

Provision of nest sites is beneficial for the welfare of laying hens in intensive production systems. The design of these nest sites has a direct effect on pre-laying behaviour. The aim of this study was to investigate the effects of screening off the entrances of the nest boxes with non-transparent flaps and providing nesting or flooring material on pre-laying behaviour. Eighteen individual Hisex brown laying hens and 18 groups of five hens were tested for 2 days in a test cage containing three nest boxes each with a different nesting material (peat, artificial turf and plastic-coated wire mesh). On one of the days the nest boxes were equipped with plastic flaps at the entrances. Pre-laying behaviour was analysed using focal sampling. Both degree of seclusion and nesting material had an effect on pre-laying behaviour of hens. Nest boxes with flaps were visited less frequently but for a longer duration per visit than nest boxes without flaps. Hens spent more time sitting and scratching, and less time standing and moving when flaps were present. Hens also received fewer pecks (group test) when nest boxes were equipped with flaps. Major differences were found between pre-laying behaviour on coated wire mesh compared to peat and artificial turf with shorter duration of nest visits (group test), more standing (group test) and moving (individual and group test), and less sitting (individual and group test) and object pecking (group test) on coated wire mesh. Differences in pre-laying behaviour on peat versus artificial turf were observed for the behaviours moving (less on peat), sitting (more on peat in the individual test) and object pecking (more on peat in the group test).

It is concluded that hens show more settled pre-laying behaviour and more nest-building behaviour in the presence of flaps at the entrances of nest boxes. These results indicate that seclusion of nest boxes with non-transparent flaps is beneficial to laying hen welfare. Differences in pre-laying behaviour also suggest that plastic-coated wire mesh is less suitable as nesting material than peat and artificial turf.     

Influence of nest-floor slope on the nest choice of laying hens

Group nests in alternative housing systems for laying hens primarily fulfil the hen's needs for seclusion and protection. Commercial nests used in Switzerland are built according to the provisions of the Swiss Animal Welfare Legislation. However, nest types can differ in aspects, such as floor slope, that could have an impact on egg-laying behaviour. Floor slope has to be designed so that eggs roll away without breaking and so that hens feel comfortable laying their eggs. In commercial nests, the slope is usually between 12% and 18%. The aim of this study was to investigate the effect of floor slope on the hen's nest preference and laying behaviour. We predicted that hens would prefer nests with a lower sloped floor for evolutionary reasons and for reasons related to comfort.Eight pens, each with 17-18 white laying hens (LSL), were equipped with two roll-away nests (0.54 m²) having different floor slopes (12% and 18%). Eggs were collected each day (from approximately 20 weeks of age until 28 weeks of age); the number of eggs in each nest and on the floor of the pens was recorded. Behaviour inside the nest was filmed for two consecutive days during the main egg-laying time from the second hour to the fifth hour (4 h) after lights came on in week 27/28. The following data were recorded: number of hens in each nest, the nest visits/egg number ratio, the number of sitting events, the body alignment of hens sitting in the nest and the number and duration of nest visits. Data were analysed with a repeated-measures ANOVA. There was no difference between the numbers of eggs in the two nests, but more hens were counted in nests with a 12% slope (p = 0.027). The ratio between the number of nest visits and number of eggs did not differ significantly between the nests. However, we counted more sitting events in the nest with 12% slope (p = 0.007). The percentage of body alignment towards the back (p = 0.044) and towards the front (p = 0.028) of the nest differed between the nests. Furthermore, for nest visits lasting between 10 and 90 min, we found significant differences in the total number of nest visits (p = 0.039). For visits in this range of duration, we also found significant differences for nest visits with sitting (p = 0.025) and for the number of nest visits with egg laying (p = 0.049). All of these differences favoured the 12% nest.Both nests were generally accepted by the hens. However, because of the higher number of hens counted in the 12% nest and the higher amounts of nest visits and sitting events found in these nests, we recommend to use nests with a floor slope of 12% rather than 18%.     

Nest preference of laying hens (Gallus gallus domesticus) and their motivation to exert themselves to gain nest access

In connection with the development of a test method for the attractiveness and appropriateness of nests for laying hens, we carried out an investigation by using a preference test and motivation measuring with the help of push doors. Hens were offered two different nest sites either consisting of a tray filled with wood shavings (litter tray) or a wooden nest box plus wood shavings (nest box). Hens were individually housed in pens (2.0 m × 2.0 m) and had free access to the nest sites until they laid their 15th egg. From that day the hens had to overcome a push door to reach the nest sites. Resistance for entrance was also increased stepwise at the door leading to the hens’ nest. The experiment ended when a hen stopped to lay in her usual nest site for four consecutive days (postexperimental period). The behaviour during the last hour before oviposition was video taped at a level of resistance of 3.5, 6.0, 7.5 and 10.0 N.The hens were categorized into nest and litter layers depending on nest choice. All but one hen pushed maximum resistances between 11.5 and 18.0 N with no differences between nest and litter layers. Behaviour did not significantly change with increasing levels of resistance, but there were significant differences between nest and litter layers. Nest layers spent more time nesting than litter layers while the latter showed a strong tendency to more exploring behaviour. For litter layers, more entries through the push door leading to their nest site and more unsuccessful pushes were detected than for nest layers. According to our results, two types of layers could be distinguished whereas the two were equally motivated to access their nest site.     

Effects of supplemental levels of hesperetin and naringenin on egg quality, serum traits and antioxidant activity of laying hens

Hesperetin and naringenin phytochemicals are naturally occurring flavanoids in citrus fruits. The purpose of this study was to evaluate the effects of supplementing different levels of extracted hesperetin and naringenin on egg quality, serum traits and antioxidant activity in laying hens. Two experiments were conducted, each for 10 weeks, in a completely randomized experiment design. Each had 100 Leghorn laying hens (26 weeks old) randomly assigned into five groups (n = 20) based on dietary categories of hesperetin 0, 0.5, 1, 2, 4 g/kg and naringenin 0, 0.5, 1, 2, 4 g/kg. Experimental results indicated that there was increased (P<0.05) egg production in the 1 g/kg naringenin-supplemented group, but lower (P<0.05) egg production in the hesperetin- and naringenin-supplemented groups given 4 g/kg. Cholesterol content (per gram yolk) and total cholesterol content (per egg) were lower (P<0.05) in the hesperetin- and naringenin-supplemented groups as compared to the control group, and the 2 g/kg hesperetin- and naringenin-supplemented groups showed the most significant difference. Both serum cholesterol and triglyceride concentrations were lower (P<0.05) in the 2 g/kg hesperetin- and naringenin-supplemented groups. The SOD and catalase activities, scavenging O₂⁻ and iron-chelating abilities were higher (P<0.05) in the 2 g/kg hesperetin- and naringenin-supplemented groups, and the trolox equivalent antioxidant capacity was higher (P<0.05) in the 2 g/kg naringenin-supplemented group. The results confirmed that both hesperetin and naringenin could lower serum and egg yolk cholesterol levels, and improve the antioxidant activities, however the measured variables generally showed significant quadratic responses to increasing amounts of the compounds. The recommended supplementation level of hesperetin and naringenin is 2 g/kg of the basal diet for reduced serum and yolk cholesterols contents and increased antioxidant capacity.     

Welfare, health, and hygiene of laying hens housed in furnished cages and in alternative housing systems

The aim of this review was to compare welfare, health, and hygienic status of laying hens housed in furnished cages and in alternative systems. In alternative systems (floor housing and aviaries), birds have more freedom of movement and a more complex environment than in furnished cages. However, housing birds in much larger flocks in alternative systems leads to an increased risk of feather-pecking. Furthermore, air quality can be poorer in alternative systems than in furnished cages. This can affect health and hygienic status. There are only limited data on a direct comparison between furnished cages and alternative systems. Therefore, there is a need for an on-farm comparison of welfare, health, and hygienic status in these systems.     

Influence of physical activity on tibial bone material properties in laying hens

Laying hens develop a type of osteoporosis that arises from a loss of structural bone, resulting in high incidence of fractures. In this study, a comparison of bone material properties was made for lines of hens created by divergent selection to have high and low bone strength and housed in either individual cages, with restricted mobility, or in an aviary system, with opportunity for increased mobility. Improvement of bone biomechanics in the high line hens and in aviary housing was mainly due to increased bone mass, thicker cortical bone and more medullary bone. However, bone material properties such as cortical and medullary bone mineral composition and crystallinity as well as collagen maturity did not differ between lines. However, bone material properties of birds from the different type of housing were markedly different. The cortical bone in aviary birds had a lower degree of mineralization and bone mineral was less mature and less organized than in caged birds. These differences can be explained by increased bone turnover rates due to the higher physical activity of aviary birds that stimulates bone formation and bone remodeling. Multivariate statistical analyses shows that both cortical and medullary bone contribute to breaking strengthThe cortical thickness was the single most important contributor while its degree of mineralization and porosity had a smaller contribution. Bone properties had poorer correlations with mechanical properties in cage birds than in aviary birds presumably due to the greater number of structural defects of cortical bone in cage birds.     

Effects of mixed housing of birds from two genetic lines of laying hens on open field and manual restraint responses

Birds from Rhode Island Red (RIR) origin show a lower fear response and less feather pecking than birds from White Leghorn (WL) origin. This study investigated whether responses in fear eliciting tests were affected if RIR and WL birds were housed together. Experimental groups contained either birds from one line only ('pure' groups) or an equal number of RIR and WL birds ('mixed' groups). These arrangements were maintained from hatch onwards, throughout the rearing and laying period. Birds were subjected to open field tests at 5-6 weeks and 17-18 weeks of age and to manual restraint tests at 7-8 weeks and 24 weeks of age. RIR birds were more active in both open field tests and in the manual restraint test at 24 weeks of age as compared with WL birds. RIR birds from pure groups were more active in the open field test at 17-18 weeks and in the manual restraint test at 24 weeks of age than RIR birds from mixed groups. These results suggest that otherwise low fearful RIR birds may adopt a higher fear response if they are housed together with more fearful conspecifics. These effects do not emerge until after 8 weeks of age.     

Influence of high vitamin E dosages on retinol and carotinoid concentration in body tissues and eggs of laying hens

The aim of the study was to contribute to the discussion of overdosing vitamin E in laying hens. A total of 45 laying hens, divided into 5 groups were fed diets supplemented with either 0; 100; 1000; 10 000 or 20 000 mg dl‐α‐tocopheryl acetate/kg diet over a period of 10 weeks. Concentrations of vitamins A and E were measured in plasma, various tissues and egg yolk. Furthermore egg yolk colour and some carotinoids were measured in egg yolks. None of the vitamin E doses significantly influenced performance of the hens. As expected, vitamin E concentration in plasma, all tissue samples and egg yolk was significantly increased with increasing tocopherol content in the diet. The egg yolk showed the highest vitamin E concentration, followed by liver and muscles. Feeding 1000 mg α‐tocopheryl acetate per kg diet resulted in an increase of vitamin A concentration in the liver. Very high doses (10 000 and 20 000 mg/kg diet) significantly decreased retinol concentration in the liver and egg yolk, as well as carotinoid concentration in the egg yolk. The lower carotinoid concentration in egg yolk resulted in a decreased intensity of egg yolk colour. A prooxidative and/or competitive effect of very high doses of vitamin E with other fat soluble substances has been discussed.     

A note on fear reaction of three different genetic strains of laying hens to a simulated hawk attack in the hen run of a free-range system

Hens well adapted to free-range systems should react quickly to avoid an attack by a predator but should also be able to return to the hen run soon after to ensure good use of the outside area. To ascertain if some strains cope better with a frightening event the fear reaction of three different genetic strains to a simulated hawk attack in a free-range system was tested. Eight groups of 21 hens composed of the three different strains (LSL, ISA brown and ISA black), were exposed to a simulated hawk attack. Fear reaction and recovery times were video recorded and the use of the hen run was observed. Although the hens did react to the simulated hawk attack as expected by running back into or in direction to the poultry house, no significant strain differences were found either in the reaction or recovery time or in the course of the hen run used. Regarding fear reaction no strain was found to have better features for use as free-range laying hen regarding the behaviour after a frightening event.     

Effect of the combined supplementation of diets with increasing levels of fish and linseed oils on yolk fat composition and sensorial quality of eggs in laying hens

Yolk fatty acid (FA) concentrations and egg quality were evaluated with respect to the inclusion of different levels of marine fish oil (MFO) and linseed oil (LO) in a basal diet. Ten diets were arranged factorially with two levels of MFO addition (15 and 17 g/kg) and five levels of linseed oil (1, 2, 3, 4 and 5 g/kg). Two commercial feeds with no n-3 FA sources added, or containing 15 g MFO/kg served as controls for egg sensorial quality traits. Type of diet did not affect egg production traits, nor total fat content in yolk or saturated and monounsaturated FA concentration in yolk fat. An increase in the inclusion of MFO from 15 to 17 g/kg increased (P<0.05) egg yolk content of total n-3 FA, C_20:5 n-3 and C_22:6 n-3 by 3.3, 9.8 and 3.5%, respectively. Linseed oil addition increased linearly (P<0.001) the level of total n-3 FA and the proportion of C_18:3 n-3, C_20:5 n-3, C_22:5 n-3 and C_22:6 n-3 retained in yolk fat by respectively 131, 12.0, 6.9 and 20.7% between extreme diets. Efficiency of retention of n-3 FA decreased (P<0.001) with dietary level of n-3 FA, and with the dietary ratio of MFO to LO. Both MFO and LO addition decreased (P<0.001) C_20:4 n-6 to C_18:2 n-6 ratio in yolk. Sensorial quality of eggs was not affected by treatments and did not differ with respect of that obtained in commercial n-3 FA enriched eggs. No interaction was found between LO and MFO addition for any of the traits studied. Regression equations have been calculated in order to predict efficiency of retention and yolk fat content of LC n-3 and n-6 FA from dietary characteristics.     

Influence of Dietary Copper Proteinate on Performance,Selected Biochemical Parameters,Lipid Peroxidation,Liver, and Egg Copper Content in Laying Hens

This study was performed to determine the effects of copper proteinate on performance, blood chemistry, lipid peroxidation status, and organs as well as copper deposition in the liver and eggs of laying hens. Seventy-two 30-week-old Bovans laying hens were distributed into four groups with three replicates. Animals were fed basal diet containing at least 17% crude protein and 2,800 kcal/kg metabolizable energy supplemented with either 0, 150, 300, or 450 mg/kg copper as copper proteinate. Supplementation of 150 and 300 mg/kg copper increased egg production, whereas 450 mg/kg copper decreased (p < 0.001). Liver copper levels were elevated in 300 and 450 mg/kg copper-supplemented groups (p < 0.001). Egg copper contents increased in all treatment groups (p < 0.01). An increase in glucose (p < 0.001) and decreases in albumin (p < 0.01) and total cholesterol (p < 0.05) levels were determined with 300 and 450 mg/kg copper. Supplementation of 450 mg/kg copper increased alkaline phosphatase and gamma glutamyl transpeptidase activities (p < 0.05), malondialdehyde, and high-density lipoprotein levels (p < 0.01) but decreased alanine aminotransferase and lactate dehydrogenase activities (p < 0.01). No gross and microscopic changes were observed in the liver and kidneys. These results indicated that 150 and 300 mg/kg copper increased egg production without having marked adverse effects, but 450 mg/kg copper altered some blood chemistry variables and reduced egg production in laying hens.     

Effects of Enterococcus faecalis on egg production,egg quality and caecal microbiota of hens during the late laying period

This study was conducted to determine the effects of diet supplementation of laying hens with Enterococcus faecalis (EF) on egg production, egg quality and caecal microbiota. A total of 360 Hy-Line Brown laying hens (72 weeks old) were divided into three groups with four replicates of 30 birds each. The laying hens were fed with the basal diet (Control), the basal diet + 3.75 · 10⁸ cfu EF/kg (Group I) or the basal diet + 7.5 · 10⁸ cfu EF/kg (Group II). The experiment lasted for 45 d. Eggs and caecal samples were collected at the end of the experiment. Results showed that dietary supplementation with EF did not affect the average daily egg weight, cracked egg rate, mortality and egg quality. However, EF supplementation caused a significantly increased laying rate and decreased feed/egg ratio (p < 0.05). The differences in caecal microbiota between Group II and the Control were significant. The relative abundance of Verrucomicrobia and Cyanobacteria at the phylum level, Rikenellaceae, Christensenellaceae and Veillonellaceae at the family level, and the Faecalibacterium, Christensenellaceae R-7 group and Eubacterium coprostanoligenes group at the genus level changed significantly in Group II compared with the Control (p < 0.05). In conclusion, the tested dietary supplementations with EF improved product performance and affected the caecal microbial community structure of laying hens during the late laying period.     

Investigations on the effects of rape oil quality,choline and methionine concentration in diets for laying hens on the trimethylamine content of the eggs,on trimethylamine metabolism and on laying performance

Abstract

An experiment was conducted to study the effects of graded levels of choline addition (0, 500, 1000 and 4000 mg/kg diet) in laying hen diets prepared either with degummed or refined rape oil on the performance, sensory properties and trimethylamine (TMA) contents of the eggs. Furthermore, the diets containing no supplemented choline or 4000 mg choline/kg diet were tested with adequate or inadequate methionine supply (4.2 vs. 2.8 g methionine/kg diet). TMA metabolism and N-balance were measured for the latter diet types, but only with the diets containing refined rape oil. Therefore, a total of 12 and 4 diets were tested in the feeding (n = 60) and balance study (n = 9). Laying performance (23 – 75 weeks of age) was not significantly influenced by increasing choline additions with the exception of feed-to-egg mass ratio which decreased significantly linearly (p _linear = 0.003). However, a significant interaction between choline addition and laying month was detected which was caused by a depression of performance of the unsupplemented control group occurring from the sixth laying month. The most obvious effect of an inadequate methionine supply was a temporary drop in performance between the third and sixth laying months. The mean TMA-concentration in pooled egg yolks [μg/g] increased with dietary choline concentration [mg/kg] in an exponentially related fashion (y = 1.14 + 4E^?10 ? x^2.71, r² = 0.962) and suggested only a minor influence of total dietary choline on TMA content up to approximately 2000 mg choline/kg. Individual TMA-concentrations varied greatly from 0.4 – 1.5 μg/g, from 2.2 – 34 μg/g and from 18.4 – 75 μg/g for eggs with a normal, aberrant and heavily aberrant odour, respectively. It is concluded that a total choline concentration of at least approximately 1500 mg/kg is necessary to maintain a maximal laying performance. An inadequate methionine supply cannot be compensated by an increased addition of choline. Neither degummed nor refined rape oil influenced the TMA content of eggs.     

Alternative methods for disposal of spent laying hens: Evaluation of the efficacy of grinding,mechanical deboning,and of keratinase in the rendering process

Besides the challenges of mortality and litter disposal, the poultry industry must find economical means of disposing of laying hens that have outlived their productive lives. Because spent hens have low market value and disposing of them by composting and burial is often infeasible, finding alternative disposal methods that are environmentally secure is prudent. The feasibility of grinding or mechanically deboning spent hens with and without prior mechanical picking was evaluated for the production of various proteinaceous by-product meals. The end products were analyzed for nutrient content and found to be high in protein (35.3–91.9% CP) and, with the exception of the feathers, high in fat (24.1–58.3%), making them potentially valuable protein and energy sources. After considering physical and economic feasibility, mechanical deboning was determined to be a logical first step for the conversion of spent hens into value-added by-product meals. Because the hard tissue fraction (primarily feathers, bones, and connective tissue) generated by mechanically deboning the hens presents the greatest challenge to their utilization as feedstuffs, attention was focused on technologies that could potentially improve the nutritional value of the hard tissue for use as a ruminant protein source. Traditional hydrolysis of this hard tissue fraction improved its pepsin digestibility from 74% to 85%; however, subsequent keratinase enzyme treatment for 1 h, 2 h, 4 h, or 20 h after steam hydrolysis failed to improve the pepsin or amino acid digestibility any further (P > 0.10). Enzyme hydrolysis did, however, increase the quantities of the more soluble protein fractions (A: 45.5, 46.6, 52.8, 51.6, and 55.8% of CP; B₁: 3.2, 9.8, 6.0, 4.6, and 4.1% of CP; B₂: 11.7, 18.1, 22.8, 29.6, and 22.0% of CP for 0, 1 h, 2 h, 4 h, and 20 h, respectively) and reduced quantities of the less soluble fractions (B₃: 30.2, 18.1, 10.8, 5.5, and 10.2% of CP; C: 9.4, 7.5, 7.6, 8.8, and 7.9% of CP for 0, 1 h, 2 h, 4 h, and 20 h, respectively). The protein digestibility of the steam hydrolyzed hard tissue fraction from the mechanical deboning of spent hens was found to be comparable to the digestibility of feather meal, but post-hydrolysis keratinase treatment did not improve feeding value for ruminants.     

Effects of Edge Habitat and Nest Characteristics on Depredation of Artificial Nests in Fragmented Australian Tropical Rainforest

Variation in nest predation levels associated with rainforest fragmentation (edge effects) was assessed in Australia's Wet Tropics bioregion. Artificial nests were placed in the forest understorey at seven edge sites where continuous forest adjoined pasture, seven interiors (about 1 km from the edge), and six linear riparian forest remnants (50–100 m wide) that were connected to continuous forest. Four nest types were also compared, representing different combinations of two factors; height (ground, shrub) and shape (open, domed). At each site, four nests of each type, containing one quail egg and two model plasticine eggs, were interspersed about 15 m apart within a 160 m transect during September–October 2001. Predators were identified from marks on the plasticine eggs. The overall depredation rate was 66.5% of 320 nests' contents damaged over a three-day period. Large rodents, especially the rat Uromys caudimaculatus, and birds, especially the spotted catbird Ailuroedus melanotis, were the main predators. Mammals comprised 56.5% and birds 31.0% of predators, with 12.5% of unknown identity. The depredation rate did not vary among site-types, or between open and domed nests, and there were no statistically significant interactions. Nest height strongly affected depredation rates by particular types of predator; depredation rates by mammals were highest at ground nests, whereas attacks by birds were most frequent at shrub nests. These effects counterbalanced so that overall there was little net effect of nest height. Mammals accounted for 78.4% of depredated ground nests and birds for at least 47.4% of shrub nests (and possibly up to 70.1%). The main predators were species characteristic of rainforest, rather than habitat generalists, open-country or edge specialists. For birds that nest in the tropical rainforest understorey of the study region, it is unlikely that edges and linear remnants presently function as ecological population sinks due to mortality associated with increased nest predation.     

Impact of weather variation on feeding behaviour, nestling growth and brood survival in Wrynecks Jynx torquilla

While habitat destruction is thought to be the most important reason for the decline of the Wryneck Jynx torquilla throughout Europe, it has been hypothesised that weather factors may also play a crucial role. We studied the impact of variations in ambient temperature and rainfall on feeding behaviour, nestling growth and daily brood survival probabilities in a population from the Swiss Alps. We recorded the frequency of food provisioning and measured nestlings’ growth on 6 days at 17 nests, and monitored the success of 181 broods from 2002 to 2006. The mean feeding frequency was 7.9 feedings per hour, and increased with temperature and with nestling age. Changes of body mass, tarsus length and of the 8th primary feather were not strongly influenced by temperature and rainfall. Body growth was negatively influenced by the initial size of the different body measures towards the end of the growing phase of the corresponding body measure, pointing towards compensatory growth. Daily brood survival probabilities declined in the course of the season and with increasing rainfall, and they increased with increasing temperature and with increasing nestling age. Our findings highlight that the effects of adverse weather on feeding behaviour, nestling growth and nest survival in Wrynecks are complex, as they alter with the age of the nestlings and possibly with the duration of the adverse weather events. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Effect of Ligustrum lucidum and Schisandra chinensis on the egg production,antioxidant status and immunity of laying hens during heat stress

Abstract

The experiment was conducted to evaluate the effect of two plants belonging to Chinese herbal medicines, Ligustrum lucidum (LL) and Schisandra chinensis (SC), on the laying performance, antioxidant status and immunity of hens during heat stress. The results showed that diets supplement with 1% of either LL or SC had beneficial effects on egg production and FCR of hens during heat stress (p < 0.05), compared with the control group. Either LL or SC significantly reduced malondialdehyde (MDA) concentration of heart, liver, sera and egg yolk. In addition, glutathione reductase (GR) activity of tissues and sera of the birds was significantly elevated by supplementation LL or SC. Furthermore, LL or SC supplementation significantly elevated lymphoblastogenese of the birds and the antibody values against Newcastle disease virus (NDV). The results suggest that diets supplement with 1% of either LL or SC may enhance egg production, immune function, and antioxidant status of hens during heat stress.     

Effects of early contact between non-littermate piglets and of the complexity of farrowing conditions on social behaviour and weight gain

In this study we tested if contact possibilities between non-littermate piglets and complexity of farrowing conditions affect the pre- and post-weaning behaviour, weight gain and skin lesions of piglets. Suckling sows were either kept in a group housing system (GH), in a single pen loose housing system (LH), or in conventional farrowing crates (FC). In the single pen systems a piglet door to the adjacent pen was opened on d 10 after farrowing in half of the pens so that piglets were able to enter the neighbouring pen (LH+ and FC+). For control, in the other half of single pens no piglet doors were opened (LH− and FC−). In the group housing system piglets also were allowed to freely move within the whole system on d 10 after farrowing. After weaning on d 28 piglets were kept in littered rearing pens in an open stable holding 20 piglets each. Piglets from contact pens were mixed with those they previously had contact to whereas piglets from control pens were mixed with unfamiliar litters. Data were obtained from 230 litters (113 sows with 1935 farrowed piglets). All piglets were scored for skin lesions immediately before and 4 days after opening the piglet doors, as well as immediately before and 4 days after moving into rearing pens. Behaviour (biting, fighting, drinking and laying) of piglets was recorded in the rearing pens in a 48-h period after weaning for 2 × 4 h. Treatments did not affect the level of skin lesions in the rearing period (H = 8.72, df 4, ns) nor daily weight gain until weaning (F_4,216 = 1.21, ns). In the 48 h after moving to rearing pens, less intensive agonistic behaviour (fighting and biting) was observed in contact piglets (H = 53.36, df 4, P < 0.0001). Four days after weaning control piglets showed significantly higher numbers and more severe skin lesions than contact piglets and, in addition, lesion scores of piglets from the larger single farrowing pens with straw bedding were significantly lower compared to the single farrowing crate (H = 33.86, df 4, P < 0.0001). The latency for lying in the new rearing pen was decreasing (F_4,93 = 25.76, P < 0.001) and the latency for drinking (F_4,81 = 3.43, P = 0.01) was increasing with decreasing complexity and space allotment of the housing system but were not related to whether the piglets have had contact to other litters before weaning. Five weeks after weaning weight gain (F_4,204 = 7.01, P < 0.0001) and BW (F_4,207 = 5.34, P < 0.001) were higher in treatments offering contact. Our results show that familiarising piglets from different litters 10 day post partum by establishing contact possibilities through a piglet door reduces social stress at weaning and increases weight gain after weaning. Farrowing pens with straw bedding and enlarged space as offered in the farrowing pens and the group housing system can further decrease the level of harmful agonistic interactions after mixing unacquainted litters at weaning and can improve the adaptation of piglets towards the new environment of the rearing pen.     

Effects of cages,plant age and mechanical clipping on plantain chemistry

In plant-insect herbivore field studies, effects of cages, plant age, and mechanical clipping on host plant chemistry are often postulated but not well documented. We examined the effects of cages (for the purpose of restraining insects on experimental plots), plant age over the course of the experiment and mechanical clipping on plantain (Plantago lanceolata) chemistry. Leaf age affected the concentrations of nitrogen and iridoid glycosides (IGs; specifically aucubin and catalpol), with higher levels in newer leaves. Caged plants had higher levels of IGs and lower concentrations of nitrogen than uncaged plants. The IG concentrations were greater in new leaves of caged plants than uncaged plants, whereas the concentrations in mature leaves were unaffected by caging. Plants that were 5 weeks older had higher levels of IGs and lower nitrogen than plants harvested 5 weeks earlier. Comparison of three studies suggested that over the summer IG concentrations increase during dry years but decrease during wet years. Plants with above-ground parts clipped and then allowed to regrow for five weeks had similar concentrations of IGs and nitrogen compared to control plants; but the regrowth plants had a lower catalpol to total IG ratio. We conclude that cages and time can have significant positive effects on iridoid glycoside concentrations and significant negative effects on leaf nitrogen concentration. But our results also indicate that the direction and magnitude of the effects of cages, time and mechanical damage are not easily predicted. Therefore, it is advisable to determine and/or control for such effects in field experiments on plant-insect interactions.