Effect of phased reduction of dietary digestible lysine density on growth performance, thigh meat, and biomechanical characteristics of tibia in broiler chickens.

In this study, growth performance, nutrient intake, thigh meat quality, fatty acid composition of thigh meat, and biomechanical characteristics of tibia of broiler chickens in response to phased restriction of dietary digestible lysine (dLys) were evaluated. A total of 180 male broiler chickens distributed to 3 experimental groups were fed control diets, 85% dLys diet in grower phase (GRO 85% dLys), or 85% dLys diets in grower and finisher phases (GRO-FIN 85% dLys). Feeding 85% dLys suppressed the feed intake that suppressed the growth performance, slaughter weight, and thigh weight of broiler chickens compared to control group (P < 0.05). Average daily dLys, Ca, and P intakes were suppressed in groups fed 85% dLys diets in comparison with control group (P < 0.05) due to the suppression of feed intake. While most fatty acid concentrations in thigh meat were not different among the groups, eicosanoic acid (C20:0) in thigh meat was greater in GRO-FIN 85% dLys group than control group (P = 0.002). Antioxidant status of thigh meat of broiler chickens was not affected by the phased restriction of dietary dLys compared to control group. Bone breaking strength and ultimate strength were greater in control group than 85% dLys groups (P < 0.05). In conclusion, phased dilution of dietary dLys to 85% of the required allowance yields weaker legs and tibia bones by suppressing the Ca and P intakes as a function of reduced feed intake in broiler chickens.

Effect of different pasture species on welfare and behavior of slow-growing broiler chickens in free-range production system.

This study investigated the effect of various pasture species on the welfare and behavior of slow-growing broiler chickens in the free-range production system. After 21 days completely indoors, the birds were permitted access to outdoor pens cultivated with one of the following pasture treatments: Medicago sativa (A), Trifolium repens (WC), Lolium perenne (PR), and a mixture (Mix, A + WC + PR). The range availability was restricted between 08:30 and 16:30 daily. It was found that pasture type had a significant effect on the fluctuating asymmetry of the face and radius length (P < 0.01). Duration of tonic immobility and blood parameters did not differ among the pasture species and between sexes at 11 weeks of broiler age (P > 0.05). Pasture treatment had no significant effect on broiler behaviors (P > 0.05). However, the age of broilers had a significant effect on pecking, dustbathing, and scratching (P < 0.01). Pecking behavior was affected by the time of the day; morning and afternoon (P < 0.01). Location had a significant effect on pecking and stretching behaviors (P < 0.01). In the study, dustbathing behavior was significantly affected by the interaction between location and age (P < 0.01), age and time of the day (P < 0.01), and location, age, and time of the day (P < 0.05). Scratching behavior was significantly affected by the interaction between location and time of the day (P < 0.05) and location, age and time of the day (P < 0.01). Stretching behavior was significantly affected by the interaction between location and age (P < 0.05) and location, age and time of the day (P < 0.05). It was concluded that access to the studied pasture species does not affect the evaluated welfare traits and observed behaviors. Therefore, it is suggested that other pasture species should be investigated to identify their effect on slow-growing strains in the free-range production system.

Forced locomotor activity improves walking ability of male turkeys and modifies carcass characteristics.

1. This trial investigated the effect of forced locomotor activity (training) on walking ability, leg posture, and growth performance, as well as carcass composition and meat quality in male fattening turkeys.2. A flock of 744 commercial turkeys was divided into three experimental groups, either without any training period (control), training from weeks 2 to 8 (short-term), or training from weeks 2 to 21 (long-term). All birds were slaughtered at an age of 21 weeks. To study the effect of short vs. long time lapse between shackling and stunning (suspension time), each training group was split into two halves that were hooked on the shackle for either 15 s or 3 min prior to stunning.3. Long-term physical training, compared to short-term or no training, resulted in better walking ability and in a lower percentage of leg malposition, as assessed at the end of fattening. No effect on final body weight was detected.4. In a subsample, the composition of 80 carcasses was determined by dissection. Long-term training favoured the percentage of the drumstick over that of the breast cut in comparison to the group without any training.5. Meat quality parameters were determined for breast muscle. The pH values 20 min post-mortem were reduced by long-term training, and the highest value was observed for a combination of no training with short suspension. After 24 h, pH values did not differ between experimental groups. The breast muscles were characterised as fast-glycolysing. Prolonged suspension time resulted in higher electrical conductivity after 24 h, and in higher a* values (redness).6. In conclusion, the study revealed that a long-term training period improved walking ability and leg posture of heavy male turkeys. Thus, training can contribute to the improvement of animal welfare in turkey husbandry. Meat quality variables of breast muscles were partially influenced by locomotor activity and suspension time.

Increased activity reduces the prevalence of woody breast in Ross 708 and Ranger Gold broilers.

Woody or wooden breast (WB) is characterized by hardening and paleness of the Pectoralis major muscle and can affect up to 85% of broilers. We hypothesized that increased locomotor activity would lead to a lower prevalence of WB and increased tibia bone quality, with a greater effect on a faster growing than a slower growing broiler strain. Ross 708 (N = 188) and Ranger Gold (N = 213) broilers were raised in 3.05×3.05 m2 pens in groups of 23 to 24 and 26 to 27, respectively. Target ages for the Ross 708 and Ranger Gold birds were 42 and 56 d. There were 8 pens per strain: 4 assigned to an exercise treatment and 4 unexercised controls. An exercise regimen was applied for 10 min every hour for 6 h during each weekday with the goal of increasing frequency of standing and walking. A perch was placed between the feeder and drinker line in the exercise treatment pens to further promote broiler activity. WB severity was determined by palpation for all birds at the target age. Tibial bone mineral content (BMC) and bone mineral density (BMD) were measured using a dual-energy x-ray absorptiometry. The Fisher's Exact Test was used to determine treatment effects on the prevalence and severity of WB. Both prevalence (Ross 708: 77.5 vs. 90.5% control, P = 0.013; Ranger Gold: 57.9 vs. 76.4% control, P = 0.005) and severity (Ross 708: 12.9 vs. 24.2% control, P = 0.02; Ranger Gold: 4.7 vs. 0.02% control, P = 0.01) were reduced by treatment. The effects of strain, treatment and their interaction on tibial BMC and BMD were analyzed using linear mixed models. Only strain affected BMC (P = 0.003) and BMD (P = 0.03), with Ross 708 broilers having higher BMC (control: 3.246 g ± 0.061; treatment: 3.251 g ± 0.058) and BMD (control: 0.177 g/cm2 ± 0.002; treatment: 0.174 g/cm2 ± 0.002) values compared to Ranger Gold's BMC (control: 2.966 g ± 0.067; treatment: 2.987 g ± 0.064) and BMD (control: 0.168 g/cm2 ± 0.002; treatment: 0.168 g/cm2 ± 0.002) values. However, per unit of final body weight, Ranger Gold birds had a significantly higher BMC (P = 0.006) and BMD (P = 0.01) than Ross 708 broilers. Promoting broiler activity can reduce the prevalence and severity of WB prevalence in fast and slow growing broilers.

Increased duration of laser environmental enrichment increased broiler physical activity and pen-wide movement without altering tibia measurements.

Inactivity and leg disorders negatively impact broiler welfare. Enrichment designed to increase barn complexity may encourage physical exercise. The study aim was to implement a second-generation laser enrichment device, previously shown to increase broiler activity, for extended periods of time and to measure behavior and tibia quality. A total of 1,360 Ross 708 broilers in 40 pens of 34 were assigned to laser enrichment or control (no laser enrichment) for 49 d. Seventy focal birds were randomly selected on d 0 for individual behavior analysis. Laser-enriched birds were exposed to 6-min laser periods 4 times daily. A 3-min novel object test was performed on all pens and tonic immobility was induced on 1 bird/pen on wk 1 and 6. Focal bird time budget and walking distance and pen-wide laser-following behavior and movement were obtained during laser periods d 0 to 8 and 1 d/wk through wk 7. Right tibias were collected from focal birds on d 49 for dual energy x-ray absorptiometry and bone breaking analysis. Time spent active during laser periods was increased on d 3, 6, and 8 and wk 2 to 3 in laser-enriched vs. control focal birds (P = 0.04). Time at the feeder was increased in laser-enriched focal birds on d 0, 3 to 4, and 8 and wk 2 and 4 (P < 0.01). Distance walked during laser periods was increased in laser-enriched focal birds on d 1, 3 to 5, 8, and wk 2 compared to the control (P < 0.01). Pen-wide movement was increased on d 0, 2, 4 to 8, and wk 1 to 5 and 7 in laser-enriched vs. control birds (P < 0.01). More laser-enriched broilers were within 25 cm of the novel object at 1 min 30 s than the control (P = 0.03), and latency to approach the novel object was reduced in both treatments at wk 6 compared to wk 1 (P < 0.01). Tonic immobility duration was increased by 123 s on wk 6 compared to wk 1, regardless of treatment (P < 0.01). Daily laser enrichment for extended periods increased bird activity without inducing fearfulness or altering tibia measures.

Individual Monitoring of Activity and Lameness in Conventional and Slower-Growing Breeds of Broiler Chickens Using Accelerometers.

Accelerometers are increasingly being investigated to detect animal behavior as a method for monitoring individual welfare that overcomes manual challenges associated with time, resource, and discrete sampling. We investigated the effects of broiler chicken hybrid (hereafter breed) and weight on accelerometer activity (activityA; calculated as percentage of time spent active (%)) and its association with lameness as a major broiler welfare concern. Accelerometers were attached to birds of different breeds on between 2 and 4 occasions from 26 to 30 days old (conventional breed CNV) and 26 to 49 days old (two slower-growing breeds SGH; SGN). At 2.2 kg, lameness was scored using a 6-point gait scoring system (0: unaffected to 5: severely lame). Linear mixed effects models and breed-stratified generalized linear models together with a random-effect meta-analysis were used for data analyses. ActivityA was lower in faster-growing, heavier birds compared to slower-growing, lighter birds, showing overall consistency with previous behavioral research, but did not vary linearly with gait score. Accelerometers offer the potential for simple broad-scale continuous monitoring of broiler chicken activity behavior that requires limited data processing. Exploration of the ability of accelerometers to capture more subtle and specific changes in behavioral patterning, such as non-linear acceleration with gait score that could indicate early development of lameness, warrants further investigation.

Research Note: Comparing methods to assess Valgus-Varus deformity in broiler chickens.

Valgus-varus deformity (VVD) is one of the leg disorders affecting health and welfare of broiler chickens. In research, several protocols are used to determine the prevalence and/or severity of VVD. This study aimed to investigate effects of five different protocols on the angulation of the tibiotarsal-tarsometatarsal joint. Angulation was determined (1) in living chickens with fixation at the femorotibiotarsal joint; (2) in dead chickens without fixation; (3) in dead chickens with fixation; (4) in dissected legs, including muscles, but without skin; (5) in dissected legs, without muscles, but with intact joints. Fixation of the leg at the femorotibiotarsal joint largely reduced the angulation of the tibiotarsal-tarsometatarsal joint. When fixation was used, no differences in angulation were found when broilers were live, dead or legs were dissected, but when no fixation was used, angulation was considerably higher, due to a large lateral deviation of the leg. It can be concluded that in intact chickens, fixation of the femorotibiotarsal joint is essential to determine VVD angulation in an appropriate way.

In pursuit of a better broiler: walking ability and incidence of contact dermatitis in conventional and slower growing strains of broiler chickens.

In this study, the mobility, incidence, and severity of contact dermatitis and litter moisture content were assessed in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG0-48 > 60 g/d) and 12 slower growing (SG) strains categorized as FAST (ADG0-62 = 53-55 g/d), MOD (ADG0-62 = 50-51 g/d), and SLOW (ADG0-62 < 50 g/d), with 4 strains in each category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 to 6 birds were tested in the latency-to-lie (LTL) and group obstacle tests 1 wk prior to the birds reaching 2 target weights (TWs) of approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). The incidence of footpad dermatitis (FPD) and hock burns (HB) were evaluated a day prior to each TW. Litter moisture content was determined biweekly from d 14 to d 56. At TW1, CONV and SLOW had longer LTL than FAST birds. At TW2, CONV, MOD, and FAST birds had similar LTL. At both TWs, CONV birds were lighter than FAST birds in the group obstacle test, yet their number of obstacle crossings was similar. At TW1, CONV birds had greater incidence of FPD than FAST and MOD, while at TW2, CONV birds had greater incidence than the other categories. The incidence of HB in CONV and MOD was greater than SLOW birds at TW1, while at TW2, the incidence of HB was greater in CONV and FAST birds vs. MOD and SLOW birds. Litter moisture content was high in all categories from d 28 onward. Our results indicate that both BW and growth rate influence leg strength and walking ability, whereas the overall high litter moisture content and to a lesser extent growth rate influenced the incidence of contact dermatitis.

Providing organic macro minerals and an elevated platform improved tibia characteristics, and increased locomotion and performance of fast- and slower-growing broilers.

Improving leg health will support broiler health and welfare. Known factors to improve leg health are: replacing inorganic by organic macro minerals in the diet, providing environmental enrichments and using slower-growing broilers. However, it remains unknown how fast- and slower-growing broilers respond to a combination of providing organic macro minerals and an elevated platform as enrichment with regard to leg health. Therefore, the aim of this study was to identify whether a combined treatment of organic macro minerals and a platform affected leg health, tibia characteristics, behavior and performance of fast- and slower-growing broilers in a semicommercial setting. The experiment had a 2 × 2 factorial arrangement, with 12.800 fast-growing (Ross 308) and 12.800 slower-growing (Hubbard JA757) broilers that were randomly allocated to a control (i.e., inorganic macro minerals without enrichment) or adapted treatment (i.e., organic macro minerals and a platform). Broilers were housed in groups of 800 per pen (47.5 m2), with 8 replicates per treatment (total of 32 pens). Performance was measured weekly and over the total rearing period. Behavior was observed via scan sampling at a target weight of 0.6 and 1.9 kg for both breeds. Walking ability (gait score), footpad dermatitis, and hock burn were assessed in 10 broilers per pen just prior to slaughter weight. Leg disorders and tibia characteristics were assessed in the same broilers at slaughter weight (2.3 kg). Hardly any interaction effects between breed and treatment were found on leg health, tibia characteristics, behavior or performance, suggesting fast- and slower-growing broilers responded to the treatment similarly. The adapted treatment improved tibia characteristics, and increased locomotion and performance, but did not affect leg disorders, walking ability or contact dermatitis in both fast- and slower-growing broilers. The positive effects of the adapted treatment on tibia characteristics in both fast- and slower-growing broilers may improve leg health, although the current study did not confirm this for leg disorders, walking ability or contact dermatitis.

Associations between behaviour and health outcomes in conventional and slow-growing breeds of broiler chicken.

Broiler chickens are prone to a range of complex health and welfare issues. To support informed selection of welfare traits whilst minimising impact on production efficiency and to address a major gap in understanding, we systematically explored associations between health and behavioural indicators of broiler welfare. One conventional (CNV, n = 350) and two slow-growing broiler breeds (SGH and SGN, respectively n = 400) were reared from hatch in pens of 50 birds. Birds were assessed for health (gait, plumage cover and dirtiness, pododermatitis, hockburn, and leg deviations) at 2.2 kg liveweight according to the Royal Society for the Prevention of Cruelty to Animals Broiler Breed Welfare Assessment Protocol. Behaviour and resource-use of 10% of birds per pen, on days 29 (all breeds) and 43 (SGH and SGN), was (i) scan sampled every 60 min between three to six and between twelve to fifteen hours after photoperiod onset; and (ii) continuously sampled sequentially from focal birds for 3 min each in a random order, during 15 min observation periods at three and twelve hours after photoperiod onset. Binary logistic generalized linear models were used, to assess respective associations between pen prevalence of each health outcome and (i) pen mean percentage scans of behaviour, and (ii) pen mean frequency and duration per 3 min focal observation of behaviour. Better growth rate and feed conversion but poorer health outcomes (mortality, gait, pododermatitis, feather cover) were more prevalent in CNV. Strong associations between behaviour and several heath indicators revealed, (i) increases in side-lying inactive, sitting inactive, and use of the litter relative to other resources, as primary and general indicators of poorer health, and (ii) increases in standing inactive, perch use, walking, Comfort, High Energy and Exploratory behaviour as primary and general indicators of better health. Of these, changes in side-lying, standing inactive, walking, Comfort and High Energy behaviour were particularly sensitive to small differences in health outcomes important for breed acceptance in high-welfare schemes. Crucially these behavioural measures additionally represent motivational and affective aspects of welfare not captured by health measures and allow opportunity for earlier intervention. Thus, to provide a comprehensive assessment of broiler experience, behaviour should be incorporated into broiler welfare assessments.