Kinematic analysis quantifies gait abnormalities associated with lameness in broiler chickens and identifies evolutionary gait differences

This is the first time that gait characteristics of broiler (meat) chickens have been compared with their progenitor, jungle fowl, and the first kinematic study to report a link between broiler gait parameters and defined lameness scores. A commercial motion-capturing system recorded three-dimensional temporospatial information during walking. The hypothesis was that the gait characteristics of non-lame broilers (n = 10) would be intermediate to those of lame broilers (n = 12) and jungle fowl (n = 10, tested at two ages: immature and adult). Data analysed using multi-level models, to define an extensive range of baseline gait parameters, revealed inter-group similarities and differences. Natural selection is likely to have made jungle fowl walking gait highly efficient. Modern broiler chickens possess an unbalanced body conformation due to intense genetic selection for additional breast muscle (pectoral hypertrophy) and whole body mass. Together with rapid growth, this promotes compensatory gait adaptations to minimise energy expenditure and triggers high lameness prevalence within commercial flocks; lameness creating further disruption to the gait cycle and being an important welfare issue. Clear differences were observed between the two lines (short stance phase, little double-support, low leg lift, and little back displacement in adult jungle fowl; much double-support, high leg lift, and substantial vertical back movement in sound broilers) presumably related to mass and body conformation. Similarities included stride length and duration. Additional modifications were also identified in lame broilers (short stride length and duration, substantial lateral back movement, reduced velocity) presumably linked to musculo-skeletal abnormalities. Reduced walking velocity suggests an attempt to minimise skeletal stress and/or discomfort, while a shorter stride length and time, together with longer stance and double-support phases, are associated with instability. We envisage a key future role for this highly quantitative methodology in pain assessment (associated with broiler lameness) including experimental examination of therapeutic agent efficacy.     

Cyclopiazonic acid production by Aspergillus flavus and its effects on broiler chickens

Cyclopiazonic acid (CPA) was purified from cultures of Aspergillus flavus, and ca. 14 g of the toxin was collected for use in feeding studies. Chicken rations were artificially contaminated with purified CPA at concentrations of 10, 50, and 100 ppm (microgram/g) and fed ad libitum to eight groups of chickens for 7 weeks. Chickens receiving feed with 100 ppm of CPA had high mortality, decreased weight gain, and poor feed conversion when compared with birds receiving other doses. Postmortem examination showed that chickens fed the two greatest doses of CPA had proventricular lesions characterized by mucosal erosion and hyperemia (100 ppm) and by thick mucosa and dilated proventricular lumens (50 ppm). Birds given 100 ppm of CPA in feed also had numerous yellow foci in their livers and spleens. Microscopic examination of tissues of birds that received 100 ppm of CPA revealed ulcerative proventriculitis, mucosal necrosis in the gizzard, and hepatic and splenic necrosis and inflammation. Birds given 50 ppm of CPA had hyperplasia of the proventricular mucosal epithelium. Birds given 10 ppm of CPA and control birds had no significant treatment-related lesions.     

Cyclopiazonic acid production by Aspergillus flavus and its effects on broiler chickens.

Cyclopiazonic acid (CPA) was purified from cultures of Aspergillus flavus, and ca. 14 g of the toxin was collected for use in feeding studies. Chicken rations were artificially contaminated with purified CPA at concentrations of 10, 50, and 100 ppm (microgram/g) and fed ad libitum to eight groups of chickens for 7 weeks. Chickens receiving feed with 100 ppm of CPA had high mortality, decreased weight gain, and poor feed conversion when compared with birds receiving other doses. Postmortem examination showed that chickens fed the two greatest doses of CPA had proventricular lesions characterized by mucosal erosion and hyperemia (100 ppm) and by thick mucosa and dilated proventricular lumens (50 ppm). Birds given 100 ppm of CPA in feed also had numerous yellow foci in their livers and spleens. Microscopic examination of tissues of birds that received 100 ppm of CPA revealed ulcerative proventriculitis, mucosal necrosis in the gizzard, and hepatic and splenic necrosis and inflammation. Birds given 50 ppm of CPA had hyperplasia of the proventricular mucosal epithelium. Birds given 10 ppm of CPA and control birds had no significant treatment-related lesions.     

The prevalence of campylobacters and arcobacters in broiler chickens

Chicken carcasses from a supermarket and from a poultry abattoir were examined using methods designed to isolate as many strains of campylobacters and related organisms as possible. Strains of arcobacter, but no campylobacters, were isolated from every carcass after enrichment. Campylobacter jejuni subsp. jejuni was isolated from all carcasses examined by direct plating and other Campylobacter -like strains were isolated from nine out of 15 abattoir carcasses by direct plating but not after enrichment. Only the Camp. jejuni subsp. jejuni strains could be identified to species level using a readily available identification scheme and/or a commercial identification kit. Examination of caecal contents from the 15 abattoir poultry yielded Camp. jejuni subsp. jejuni and Campylobacter -like strains from 15 and eight by direct plating, and from six and nine after enrichment, respectively. Four sites in the intestine of the abattoir birds (60 samples) were examined for arcobacters and only one strain was isolated. This indicates that arcobacters are probably not normal inhabitants of the poultry intestine. Poultry is a rich source of other campylobacteria besides the thermophilic Campylobacter spp.     

The effect of level of straw bale provision on the behaviour and leg health of commercial broiler chickens

This study aimed to assess the effect of the number of straw bales (SBs) provided on the behaviour and leg health of commercial broiler chickens. Houses containing ~23 000 broiler chickens were assigned to one of two treatments: (1) access to 30 SBs per house, ‘30SB’ or (2) access to 45 SB per house, ‘45SB’. This equated to bale densities of 1 bale/44 m² and 1 bale/29 m² of floor space within houses, respectively. Treatments were applied in one of two houses on a commercial farm, and were replicated over six production cycles. Both houses had windows and were also artificially lit. Behaviour was observed in weeks 3 to5 of the cycle. This involved observations of general behaviour and activity, gait scores (0: perfect to 5: unable to walk) and latency to lie (measured in seconds from when a bird had been encouraged to stand). Production performance and environmental parameters were also measured. SB density had no significant effect on activity levels (P>0.05) or walking ability (P>0.05). However, the average latency to lie was greater in 30SB birds compared with 45SB birds (P<0.05). The incidence of hock burn and podo dermatitis, average BW at slaughter and levels of mortality and culling were unaffected by SB density (P>0.05). The results from this study suggest that increasing SB levels from 1 bale/44 m² to 1 bale/29 m² floor space does not lead to significant improvements in the welfare of commercial broiler chickens in windowed houses.     

Lameness and its relationship with health and production measures in broiler chickens

The aim of this study was to explore lameness and the associations between lameness and health/production measures of animal welfare in commercial broiler production, using the Welfare Quality® protocol for broilers. A total of 50 flocks were included in the sample and farm visits were conducted for lameness scoring at a mean age of 28.9 days. The percentage of animals (n=7500) in the six different gait score (GS) categories were GS0: 2.53%, GS1: 44.19%, GS2: 33.84%, GS3: 16.32%, GS4: 2.36% and GS5: 0.53%. Production and other welfare data were collected for each flock after slaughter. Higher gait scores were associated with increased hock burn score (P<0.02), increased footpad dermatitis score (P<0.01), reduced bird cleanliness score (P<0.01) and peat litter (P<0.01). Although not statistically significant, there was a tendency for increased flock gait score being associated with wet litter (P=0.07). In addition, condemnations at postmortem inspection were associated with increasing gait scores (P<0.05), indicating that at least a portion of the lameness cases display pathological changes on the carcasses. In conclusion, 19%of the birds showed moderate-to-severe lameness, which was associated with several production or health and welfare observations including feather cleanliness and condemnations as unfit for human consumption at slaughter. Although stocking density and growth rate are already known key factors for lameness, associations of lameness with hock burns, footpad dermatitis and cleanliness of the birds suggest that a suboptimal physical environment (e.g. litter- and air quality) may be detrimental to leg health. Further studies are needed to explore these associations in more detail.     

Detoxification of mycotoxins by probiotic preparation for broiler chickens

Biological decontamination of mycotoxins using microorganisms is one of the well known strategies for the management of mycotoxins in foods and feeds. Among the different potential decontaminating microorganisms,Saccharomyces cerevisiae and lactic acid bacteria represent unique groups, which are widely used in food fermentation and preservation. The aim of this study was to determine the influence of spontaneous fermentation with the use of probiotic bacteria and yeast (Lactobacillus paracasei/casei ŁOCK 0920,L. brevis ŁOCK 0944,L. plantarum ŁOCK 0945,Saccharomyces cerevisiae ŁOCK 0142), on reduction of sum of aflatoxines (B₁, B₂, G₁, G₂) and ochratoxin A concentration during fermentation and the microflora pattern during fermentaton. The probiotic bacteria and yeast applied creates a starter culture for flour fermentation that has a stable feature of detoxication of aflatoxines and especially ochratoxin A. Presented at the 28^th Mykotoxin-Workshop, Bydgoszcz, Poland, May 29–31, 2006     

Colonization of broiler chickens by waterborne Campylobacter jejuni.

Chickens on a broiler farm in southern England were found to be colonized with Campylobacter jejuni of a single serotype, Lior 1 Penner 4. The farm was the sole supplier of a local slaughterhouse associated with a campylobacter outbreak in 1984 caused by this serotype. The serotype persisted on the farm for at least 18 months after the outbreak; its prevalence in the human population served by the farm remained high until it disappeared from the farm in 1986. The possible sources and routes of transmission of C. jejuni to the broilers on the farm were investigated. The results showed that vertical transmission, feed, litter, small mammals, and environmental or airborne cross-contamination between sheds or successive crops could be excluded as persistent sources of C. jejuni. The predominant source of C. jejuni on the farm was shown to be the water supply. Direct microscopy and fluorescent antibody methods revealed presumptive campylobacters throughout the farm's water system. Campylobacter-free chickens raised in an animal house and given water from the farm supply became colonized with the serotype of C. jejuni endemic on the farm (Lior 1 Penner 4). An intervention program based on water chlorination, shed drinking system cleaning and disinfection, and withdrawal of furazolidone from feed reduced the proportion of birds colonized with campylobacter from 81 to 7% and was associated with a 1,000- to 10,000-fold reduction in campylobacters recoverable from the carcasses. Two months after the end of the intervention program colonization of the birds returned to high levels (84%), indicating that there was a temporal association between intervention and reduced colonization with C. jejuni. Investigations continue to establish the general applicability of these findings.     

The relationship between measures of fear of humans and lameness in broiler chicken flocks

In the Welfare Quality® assessment protocol for broilers, the touch test is included to assess the human–animal relationship in the flock. The test is designed to measure the animals’ fear of humans, assuming that broilers will withdraw from the observer if they are fearful. However, many broilers close to slaughter age have impaired walking ability, and the results from the touch test may thus be biased by lameness and poor leg health. As the touch test is currently being used in several countries to assess human–animal relationship in broilers, there is an urgent need to examine this potential relationship for a further validation of the test. In the present study, fear of humans was assessed in 50 randomly selected Norwegian broiler flocks, using the touch test as described in the Welfare Quality® protocol for ty broilers. Leg health was assessed by examining the gait of 150 random birds in each of the flocks, using a six-point gait score scale from 0 to 5. The coefficient for the relationship between touch test score and gait score was 0.034 (P<0.001), indicating that the animals express less fear as assessed by the touch test when the gait scores increase. This implies that the touch test may be confounded by impaired walking ability and therefore might be a suboptimal method of assessing fear of humans and human–animal relationship in broilers. In conclusion, the results from this study suggests that the touch test must be further validated in broilers and perhaps be replaced with a fear test that doesn’t rely on walking ability.     

Cecal microbiome divergence of broiler chickens by sex and body weight

The divergence of gut bacterial community on broiler chickens has been reported as potentially possible keys to enhancing nutrient absorption, immune systems, and increasing poultry health and performance. Thus, we compared cecal bacterial communities and functional predictions by sex and body weight regarding the association between cecal microbiota and chicken growth performance. In this study, a total of 12 male and 12 female 1-day-old broiler chickens were raised for 35 days in 2 separate cages. Chickens were divided into 3 subgroups depending on body weight (low, medium, and high) by each sex. We compared chicken cecal microbiota compositions and its predictive functions by sex and body weight difference. We found that bacterial 16S rRNA genes were classified as 3 major phyla (Bacteroidetes, Firmicutes, and Proteobacteria), accounting for > 98% of the total bacterial community. The profiling of different bacterial taxa and predictive metagenome functions derived from 16S rRNA genes were performed over chicken sex and bodyweight. Male chickens were related to the enrichment of Bacteroides while female chickens were to the enrichment of Clostridium and Shigella. Male chickens with high body weight were associated with the enrichment of Faecalibacterium and Shuttleworthia. Carbohydrate and lipid metabolisms were suggested as candidate functions for weight gain in the males. This suggests that the variation of cecal bacterial communities and their functions by sex and body weight may be associated with the differences in the growth potentials of broiler chickens.     

Impaired development of broiler chickens by stress mimicked by corticosterone exposure

The effects of corticosterone (CORT) administration on the development of muscular tissues of broiler chickens (Gallus gallus domesticus) fed with diets differing in lipid content were investigated. The experimental chickens were given one of two experimental diets: high lipid diet (9.9% crude fat) or control diet, from 21 d of age. At 28 d of age, half of the chickens in each dietary treatment were exposed to CORT treatment, supplemented with 30 mg CORT/kg diet for 12 days, while the other half continued to consume the former diet. The zootechnical parameters were recorded at 21, 28, 35 and 39 d, and a blood sample was obtained from 8 birds of each group, respectively. The growth performance of broiler chickens was significantly depressed by CORT administration, but not by dietary treatment. Corticosterone treatment resulted in enhanced energy expenditure. The results indicate that the development of breast muscle was more susceptible to stress mimicked by CORT administration. The results suggest that corticosterone administration enhanced hepatic fatty acid synthesis and resulted in the redistribution of energy to abdominal store from peripheral tissues. Diet rich in lipid content was favorable to the central fat deposit in stressed broiler chickens.     

Inheritance of fertility in broiler chickens

Background

The fertility of a chicken''s egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period.

Methods

Longitudinal models including both random genetic and permanent environmental effects of both the female and her male mate were used to model the proportion of fertile eggs in a pedigree broiler population over the ages 29-54 weeks.

Results

Both the male and the female contribute to variation in fertility. Estimates of heritability of weekly records were typically 7% for female and 10% for male contributions to fertility. Repeatability estimates ranged from 24 to 33%, respectively. The estimated genetic variance remained almost constant for both sexes over the laying period and the genetic correlations between different ages were close to 1.0. The permanent environment components increased substantially towards the end of the analyzed period, and correlations between permanent environment effects at different ages declined with increasing age difference The heritability of mean fertility over the whole laying period was estimated at 13% for females and 17% for males. A small positive correlation between genetic effects for male and female fertility was found.

Conclusion

Opportunities to improve fertility in broiler stocks by selection on both sexes exist and should have an impact throughout the laying period.     

The aversion of broiler chickens to concurrent vibrational and thermal stressors

The requirement for assessing the effects of multiple concurrent stressors in improving the welfare of broiler chickens during transport has not been widely recognised. A discrete-choice technique was used to investigate the aversion of broiler chickens to concurrent vibrational and thermal transport stressors. In experiment 1, 12 female broiler chickens, aged 42+/-3 days were studied individually using two choice-chambers. Each chamber had four compartments connected via a central zone and offered four treatments; thermal (T: air temperature; 40 degrees C, 21% RH), vibrational (V: frequency; 2Hz, acceleration; 1ms(-2)), concurrent vibrational and thermal (VT) and no applied stressors (N). Coloured compartment wall panels, allocated at random, assisted chickens' identification of compartments. Birds were fasted overnight and were required to make five consecutive choices on each of four consecutive days. A choice was defined as entering a compartment and feeding (5g pellets), whereupon confinement for 60min was initiated. Choices were totalled over all birds and analysed using a log-linear generalised linear model. The vibration was significantly avoided (V and VT versus N and T; P<0.05) but the thermal stressor was not (T and VT versus N and V; P>0.05) and there was no interaction. In experiment 2, the procedure was repeated with 12 more birds and modifications to increase method sensitivity and maximise bird learning. Choices were more disparate than before with vibration avoided to a greater extent (V and VT versus T and N; P<0.01) but there was still no main effect of the thermal treatment or a significant interaction. Substantial differences between individuals were observed in both experiments. The overall response to vibration supported previous findings for short-term exposure, however, non-avoidance of the thermal treatment was unexpected. Possibly, the birds were unable to associate the delayed heat stress with the compartment. Alternatively, the thermal conditions were not perceived as aversive either initially or throughout the 60min confinement. The preference method provides a useful starting point for assessing combinations of stressors which affect broiler welfare, allowing relative ranking of treatments from an animal-centred perspective.     

Effects of environmental enrichment on activity and lameness in commercial broiler production

The aim of this pilot study was to investigate the effects of commercially applied environmental enrichments on behavior and lameness in broilers. Two consecutive flocks of broilers were observed at 16 days and 30 days of age to investigate differences between enriched (peat, bales of lucerne hay, and elevated platforms) and control birds with regards to behavioral activities and lameness. More running (p < .001), worm running (p = .006), play fighting (p = .015), dust bathing (p = .009), and ground pecking while standing (p < .001) were observed at 16 days than at 30 days. Across both ages, enriched birds showed more wing flapping (p = .016), wing stretching (p = .002), body shaking (p = .002), ground scratching (p < .001), and ground pecking while standing (p < .001) and lying (p = .003) compared with control birds. Even when no enrichments were close, enriched birds showed more body shaking (p = .008) and ground pecking while standing (p < 0.001) and lying (p = .010) than birds in comparable locations in control pens. There was a tendency for a lower gait score (i.e., reduced lameness) with the enriched treatment (p = .077). In conclusion, enriched birds showed higher levels of several activities compared with control birds, and demonstrated higher levels in areas where no enrichments were present.     

Play behaviour,fear responses and activity levels in commercial broiler chickens provided with preferred environmental enrichments

There is currently a lack of research investigating the effectiveness of commercial broiler enrichments, and in particular the ability of these additions to create opportunities for positive welfare. One aim of this study was to investigate whether offering broiler chickens enrichments that have recently been found to be preferred leads to increased levels of activity. A second aim was to investigate the emotional effects of provision of these enrichments by assessing levels of fearfulness and play-like activity. Commercially housed broilers were assigned to treatment houses containing either: (1) platform perches, (2) platform perches+peat dust baths, (3) no enrichment (control). Activity levels and play behaviours in unenriched areas of the house were measured in weeks 3, 4 and 5. Levels of active behaviours, such as foraging and locomotion, were determined from video recordings of undisturbed birds in unenriched areas of the house. To stimulate play-like behaviours an observer walked through the birds, displacing them and creating a space. The broilers using the space were then filmed for 5 min and the occurrences of frolicking, sparring and food-running were recorded. Fearfulness of broilers in unenriched areas of the house, and also when using enrichments, was measured using observer avoidance tests in week 5. We found that creating space among the broilers was a successful method of stimulating play (largely sparring and frolicking), with play being observed in 93% of videos, however the presence of enrichments did not have an effect on the level of play recorded (P>0.05). There was also no treatment effect on activity levels of broilers in unenriched areas (P>0.05), however levels of overall activity decreased as broilers aged. Compared with the control, flight distances in unenriched areas were significantly lower in the perches+dust bath treatment (P=0.026), and were numerically lower in the perches treatment. This suggests a reduction in fearfulness with increased environmental complexity, and thus possible welfare benefits. It is suggested that further research should investigate whether increasing the level of provision of these enrichments leads to more marked improvements in welfare.     

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.     

The effect of humidity on growth and feed conversion of broiler chickens

The optimum range of relative humidity for chicken after brooding is between 50 and 70%. The range is between 60% and 80% relative humidity during the brooding period. The higher humidities seem to favor better growth and feed conversion. However, one must be careful since the higher humidities seem to favor problems with wet litter, housing and some diseases. Dehydration did not occur under conditions of these tests. Feed conversion, feathering,pigmentation and gain of the chicken is aversely affected by high relative humidities above 26.7°C temperature. Chicken raised at 35° to 37.8°C regardless of humidity do not perform satisfactorily. The importance of water cannot be overlooked as was shown in these trials.The chicken requires approximately 0.68 kg of water per kg of feed consumed and almost 1.59 kg of water for each kg of gain. If the water is unpalatable, contaminated or high in mineral salts consumption can be reduced thus causing a reduction in growth and efficiency.

---

Zusammenfassung Der optimale Bereich der Relativen Feuchte für Hühner nach dem Brüten liegt zwischen 50 und 70%, der Bereich während der Brutperiode zwischen 60 und 80%. Höhere Feuchten scheinen ein besseres Wachstum und eine bessere Nahrungsverwertung zu begünstigen. Jedoch muss man vorsichtig sein, weil die höheren Feuchten Schwierigkeiten wie feuchte Streu und Behausung sowie einige Krankheiten begünstigen. Austrocknung kam unter diesen Versuchsbedingungen nicht vor. Futterverwertung, Gefieder, Pigmentierung und Gewichtszunahme werden durch hohe Relative Feuchten bei Temperaturen über 26,7°C ungünstig beeinflusst. Hühner, die bei 35 bis 37,8°C ohne Rücksicht auf die Relative Feuchte gezüchtet wurden,befriedigten nicht. Die Bedeutung des Wassers darf nicht übersehen werden. Das Huhn benötigt annähernd 0,68 kg Wasser je Kg Futterverbrauch und fast 1,59 kg Wasser für jedes kg Gewichtszunahme. Wenn das Wasser nicht schmackhaft oder verunreinigt ist oder einen hohen Gehalt von Mineralsalzen besitzt, kann der Verbrauch reduziert und so eine Beeinträchtigung des Wachstums und der Leistungsfähigkeit verursacht werden.

---

Resume L'humidité optimum pour le développement des poulets fraîchement éclos est située entre 50 et 70%. Durant la couvaison, cet optiumum se situe entre 60 et 80%. Une humidité plus élevée semble favoriser la croissance et une meilleure mise en valeur de la nourriture. Il faut pourtant être prudent dans le réglage de l'humidité, car, si elle est trop élevée, elle semble favoriser certaines maladies et apporte des difficultés d'élevage dues au poulailler lui-même et au fait que la litière est humide. On n'as pas constaté de phénomènes de déshydratation au cours de ces essais. Au-dessus de 26,7°C, une forte humidité influence de façon défavorable la nutrition, le plumage, la pigmentation et le développement des poulets. Des poulets élevés entre 35° et 37,8°C sans qu'on tienne compte de l'humidité ne donnent pas satisfaction. Dans les présents essais, on a également mis en évidence l'importance de l'eau. Les poulets ont besoin d'environ 0,68 kg d'eau par kg de nourriture et d'à peu près 1,59 kg d'eau par kg de poids. Si l'eau a un goût désagréable, si elle est polluée ou si elle présente une forte teneur en sels minéraux, les poulets en boivent moins et leur développement en est diminué d'autant.

---

---

Presented at the Fourth International Biometeorological Congress, New Brunswick, N.J., 26 August–2 September 1966. Scientific Article Number A-1291. Contribution No. 3832 of the Maryland Agricultural Experiment Station.     

Drinking behaviour of broiler chicks

A study of drinking behaviour of individual broiler breeder chicks from hatching to 5 weeks of age was conducted. The action patterns involved in obtaining a drink as well as water consumption were described quantitatively and qualitatively. Over the experimental period, the action patterns of drinking were modified gradually. Marked changes in immersion angle, swallowing angle and distance from the waterer were evident. All birds made progressively fewer trips to the waterer to take a larger number of higher volume drinks. This information is essential for future design of improved watering equipment to better complement the natural drinking behaviour of broiler chickens.