The effects of long (C20/22) and short (C18) chain omega-3 fatty acids on keel bone fractures, bone biomechanics, behavior, and egg production in free-range laying hens.

Keel fractures in the laying hen are the most critical animal welfare issue facing the egg production industry, particularly with the increased use of extensive systems in response to the 2012 EU directive banning conventional battery cages. The current study is aimed at assessing the effects of 2 omega-3 (n3) enhanced diets on bone health, production endpoints, and behavior in free-range laying hens. Data was collected from 2 experiments over 2 laying cycles, each of which compared a (n3) supplemented diet with a control diet. Experiment 1 employed a diet supplemented with a 60:40 fish oil-linseed mixture (n3:n6 to 1.35) compared with a control diet (n3:n6 to 0.11), whereas the n3 diet in Experiment 2 was supplemented with a 40:60 fish oil-linseed (n3:n6 to 0.77) compared to the control diet (n3:n6 to 0.11). The n3 enhanced diet of Experiment 1 had a higher n3:n6 ratio, and a greater proportion of n3 in the long chain (C20/22) form (0.41 LC:SC) than that of Experiment 2 (0.12 LC:SC). Although dietary treatment was successful in reducing the frequency of fractures by approximately 27% in Experiment 2, data from Experiment 1 indicated the diet actually induced a greater likelihood of fracture (odds ratio: 1.2) and had substantial production detriment. Reduced keel breakage during Experiment 2 could be related to changes in bone health as n3-supplemented birds demonstrated greater load at failure of the keel, and tibiae and humeri that were more flexible. These results support previous findings that n3-supplemented diets can reduce fracture likely by increasing bone strength, and that this can be achieved without detriment to production. However, our findings suggest diets with excessive quantities of n3, or very high levels of C20/22, may experience health and production detriments. Further research is needed to optimize the quantity and type of n3 in terms of bone health and production variables and investigate the potential associated mechanisms.

Impact of a mixed chain length omega-3 fatty acid diet on production variables in commercial free-range laying hens.

1. Previous studies found beneficial effects on the prevalence of keel fractures and bone health in laying hens receiving a short chain ω3 fatty acid diet. However, subsequent work using a mixed short and long chain ω3 diet (MCD) found little benefit to bone health and substantial production losses. 2. The current study examined commercial use of a mixed chain length ration in multiple farms and flocks and identified a detrimental effect on productivity including: mortality, number of poor quality eggs, hen daily average, feed consumption, and increased egg weight. 3. Production data were acquired from 11 flocks housed on 5 farms and modelled using MlwiN, a statistical package developed for analysis of hierarchical data. Production responses were individually modelled with duration of exposure to the diet, age of introduction, flock size and farm, included as prediction variables. 4. Analysis indicated birds receiving the MCD manifested dramatic increases in mortality, poor quality eggs, mean egg weight, feed consumption and decreased production in comparison to control flocks receiving a standard ration. Increased exposure time appeared to increase the magnitude of the diet effect. 5. Although no data were collected to explain the potential mechanisms of this diet, the authors discuss several possible scenarios including excessive long chain ω3 content overwhelming eicosanoid regulatory capacity and changes in behaviour patterns.

Prevalence and factors associated with it, of birds dead on arrival at the slaughterhouse and other rejection conditions in broiler chickens.

1. Standardised data on husbandry were recorded for a flock of birds in one house on each of 150 broiler farms in the UK during the 4 d prior to slaughter. 2. For each flock, the incidence of birds found dead on arrival (DoAs) and the Meat Hygiene Service carcase rejection records were recorded at the slaughterhouse. 3. The mean percentage of birds in each flock found DoA was 0.12% (range 0-0.64%) and the mean percentage of Total Carcase Rejects (TCRs) for each flock was 1.23% (range 0.07-5.51%). 4. A general linear model was developed to examine factors associated with flock percentage DoAs. Assuming a linear relationship, all other factors remaining the same, a one percentage point (PP) increase in small/emaciated birds will result in a 0.155 PP increase in DoAs and a 1 PP increase in wheat in diet 4 will result in a 0.003 PP decrease. An increase by one in the total number of vaccines administered will cause a 0.029 PP decrease in DoAs, a 1 g increase in live weight at slaughter will be associated with a 0.000043 PP increase and a 1 PP increase in mortality on farm would be associated with a 0.000044 PP increase. A 1 PP increase in Ross birds decreases DoAs by 0.0004 PPS: there is also a seasonal effect. 5. The model developed for flock percentage TCRs found that a 1 PP increase in wheat in diet 3 will result in a 0.052 PP decrease in TCRs and a 1 PP increase in Ross birds will cause a 0.009 PP decrease. A 1 PP increase in birds culled on farm will be associated with a 0.03 PP increase in TCRs and the diagnosis of disease during the flock cycle increases TCRs by 0.397 PPs. A one day increase in age at slaughter will result in a 0.046 PP increase in TCRs.

Estimating the body temperature of groups of pigs by thermal imaging.

Measurements on 28 pens of pigs containing 384 animals to be slaughtered at a commercial abattoir showed that the mean ear temperatures of the pigs in each pen, measured with a thermal imaging camera, were significantly correlated (r=0.71, P<0.001) with the mean temperature of the blood the pigs lost at exsanguination. In measurements on 220 pigs in 16 of the 28 pens, the mean activity of serum creatine kinase was positively correlated with the mean ear temperature (r=0.55, P<0.05) and the mean concentration of serum cortisol was positively correlated with the mean blood temperature (r=0.50, P<0.05), suggesting that the hotter pigs were suffering from a higher level of stress.

Comparison of the effects of fan-assisted and natural ventilation of vehicles on the welfare of pigs being transported to slaughter.

A total of 417 pigs with an estimated average liveweight of 91 kg were transported to slaughter in three journeys, carried out in late June, each consisting of a three-hour drive followed by a one-hour holding period at the slaughter plant before they were unloaded. The pigs were accommodated on the lower two decks of a three-deck articulated lorry, each deck having five equal-sized pens; half were kept in naturally ventilated pens and half in pens with fan-assisted ventilation. The pigs' body temperature was recorded as the temperature of the blood lost at exsanguination, and as the temperature of the inner surface of the ear measured by thermal imaging. The pigs carried on the upper deck were hotter than those carried on the lower deck, and the pigs carried at the front of the vehicle were hotter than those at the back. There were small differences between the temperatures of the pigs in the different pens, but overall the temperatures of the pigs kept in pens with fan-assisted ventilation were no lower than those of the pigs kept in pens with natural ventilation. The higher temperature of the pigs transported in the front of the vehicle was associated with significantly higher serum concentrations of cortisol and activities of creatine kinase, and a tendency to higher albumin concentrations and osmolality, suggesting that they may have been exposed to more physical and psychological stress, and were possibly slightly more dehydrated, than the pigs in the rearmost pens. The type of ventilation had no effect on the blood composition of the pigs.

The response of pigs to being loaded or unloaded onto commercial animal transporters using three systems.

Groups of pigs were subjected to three different systems of loading and unloading to and from commercial animal transporters. The systems under trial were: the use of a hydraulic tail-lift, a tail board ramp at an angle of 18 degrees and a modular system. The module was a container 2 m x 2.4 m x 1 m high into which the pigs were loaded. The module could then be lifted on and off the lorry with a fork lift truck. Non-invasive monitoring techniques were used to study the responses of the pigs. A subjective handling score, time taken to load and unload, skin temperature, heart rate and salivary cortisol were recorded. Loading and unloading were subjectively assessed as being easiest and quickest using the modular system, which also appeared to be less physically demanding for the animals, as evidenced by lower heart rate and a reduced maximum heart rate. However, with the modular system, elevated cortisol was found during the loading, unloading and resting periods. This could be interpreted as indicating that the pigs were unable to settle in the module and suffered some small degree of stress, which might become more of a problem during prolonged transport. Of the other two systems, there appeared to be little difference between the hydraulic tail-lift and the ramp.

Effect of bone strength on the frequency of broken bones in hens.

Bird weight, breaking strength of humerus and tibiotarsus and the number of bones broken during culling were recorded for four breeds of end-of-lay hens housed in battery cages. The probability of a bone being broken increased with bird weight and decreased with increasing bone strength. Bone strength increased with bird weight within each breed but the increase in strength was not great enough to prevent the extra damage suffered by heavier birds. There were differences in tibiotarsal strength between the four breeds of bird but overall no breed was more likely to suffer from broken bones than another. The rate of increase of bone strength with weight was similar between breeds and between humerus and tibiotarsus. The results show that differences in bone strength due to the type of housing system in which birds are kept are great enough to affect the ease with which bones are broken during bird handling during removal from cages at the end of lay.

Observations on the physiological effects of pithing cattle at slaughter.

Pithing cattle after captive bolt stunning, by thrusting a rod into the cranial cavity, causes violent muscular activity. The present observations have shown that this does not result in a rapid fall in the muscle pH similar to that occurring after electrical stimulation. The claim that pithing for a greater length than usual down the spinal cord causes marked enlargement of the spleen has not been substantiated.

Caffeine stimulated lipolysis protects pigs against catecholamine-induced dark cutting.

High ultimate pH dark cutting meat was obtained in Pietrain pigs following overnight intravenous infusion of the ß-adrenergic agonist, isoproterenol. This effect was enhanced by simultaneous administration of the antilipolytic agent nicotinic acid and completely reversed by pretreatment of the animals with caffeine (which stimulates lipolysis). These results suggest that the availability of energy substrates from adipose tissue (free fatty acids and glycerol) is an important factor in the production of dark cutting meat. Stimulation of lipolysis in animals prior to pre-slaughter stresses (such as transport and lairing) could possibly reduce the incidence of dark cutting meat.

The time required for recovery from mixing stress in young bulls and the prevention of dark cutting beef.

Two trials were conducted in which a total of twenty-eight Friesian bulls (12 months old) were slaughtered 0, 1, 2, 4, 7, 9 or 10 days after they had been mixed with unfamiliar animals overnight. The resulting behavioural interactions and associated physical activity led to large rises in plasma creatine phosphokinase (CPK) activity and free fatty acid (FFA) concentration and a decrease in plasma lactate. In the second trial the relative number of interactions engaged in by each animal was estimated. Bulls which exhibited the most interactions had the highest levels of plasma CPK and FFA after mixing. Liver and muscle glycogen were depleted by mixing. Animals killed on days 0 and 1 after mixing had low concentrations of liver glycogen compared with animals allowed longer to recover. Concentrations of glycogen in the M. longissimus dorsi (LD) had recovered by day 4 and in the M. psoas by day 2. Muscle glycogen concentrations were reflected in the ultimate pH (pHu) of the meat. All animals killed immediately after mixing produced carcasses with pHu>6. in the LD. By the second day of recovery muscle glycogen stores had been repleted sufficiently so that all animals had muscles with pHu<6. However, the LD from these animals was still very slightly darker than those killed after 7 or more days of recovery although this was probably not commercially significant. It was concluded that, if young bulls from separate rearing groups are mixed before slaughter, either on the farm or during lairage, then they require resting with food for at least 48 h before being killed to ensure that no carcasses are produced with high pHu in the musculature.

The problem of broken bones during the handling of laying hens--a review.

The major welfare concern during the handling of laying hens is that of broken bones. With particular reference to the United Kingdom, this paper reviews the work that has been done to quantify the problem, to examine the causes, and to investigate factors that affect it. The number of freshly broken bones found in live birds prior to slaughter and the number of old healed breaks found at slaughter are unacceptably high. End-of-lay hens from battery cages have especially fragile bones and these are easily broken during the rough handling that is received during depopulation. Birds from more extensive laying systems have stronger bones and suffer fewer breaks during depopulation but have a greater prevalence of old healed breaks. The old breaks occur as a result of collisions due to poor design within these housing systems. The number of fresh breaks can be reduced by increasing bone strength and handling birds with more care. The numbers of old breaks can be reduced by better design of housing systems and the physical environment within them.

Broiler stunning and meat quality.

The effects of electrical and concussion stunning on meat and carcass quality of broilers were compared. Broiler chickens (n = 165) were subjected to treatments: 1) electrical stunning with no fibrillation, 2) electrical stunning with fibrillation, 3) concussion stunning with restraint, or 4) concussion stunning with no restraint. Electrical stunning (100 V, 80 mA, 50 Hz sinusoidal waveform alternating current) was applied for 3 s. Concussion was applied using a nonpenetrative captive bolt gun with or without restraint. We assessed broken bones, hemorrhages, meat quality defects, blood loss, pH at 10 min and 24 h, and texture from breasts filleted 3 h and 24 h postmortem. Electrically stunned birds showed a significantly higher incidence of broken bones (P < 0.0001), coracoid and furculum bone hemorrhages (P < 0.0001), and nonbone hemorrhages (P < 0.0001) than birds stunned by concussion. However, the incidence of red wing tips (P < 0.005) and shoulder hemorrhages was significantly higher (P < 0.05) in concussion-stunned birds than electrically stunned birds. Electrically stunned and nonfibrillated birds had the fastest blood loss rate. The pH value at 10 min was the lowest in concussion-stunned and unrestrained birds. Breast muscles from concussion-stunned birds that were filleted at 3 h postmortem were more tender than those from birds stunned electrically (P < 0.05). We concluded that concussion stunning could be advantageous for early filleting.

Effect of stunning current on carcase quality in chickens.

The effect of the stunning current at slaughter on carcase quality was examined in 1845 broiler chickens. As the current was increased there was an increase and then a decrease in the incidence of red wingtips and in haemorrhages of the wing veins and the shoulder joint. The incidence of deep breast muscle haemorrhages increased above about 130 mA, and the incidence of broken bones increased between 75 and 170 mA. The incidence of carcase defects was lowest when either less than 130 or greater than 190 mA was used to stun the birds.

Effect of very low pulsed direct currents at high frequency on the return of neck tension in broilers.

Broiler chickens were stunned electrically for one second or 10 seconds with a unipolar pulsed direct current (DC) at 550 Hz. The effectiveness of the stun was assessed from the birds' behaviour. All the birds were stunned effectively when more than 15 mA true root mean square DC was applied for either period. An increase in the duration of the applied current resulted in an increased duration of unconsciousness. However, the unipolar pulsed DC at 550 Hz did not induce cardiac arrest, and it must therefore be accompanied by a prompt and effective neck cut, severing both carotid arteries.

The role of electrical stunning, bleeding and plucking efficiency on the downgrading of chicken carcases.

This study examined the effects of inducing a cardiac arrest at electrical stunning, in combination with impaired bleeding and severe plucking, on the incidence of haemorrhages and broken bones in chicken carcases. It was concluded that with the possible exception of breast muscle haemorrhages none of the downgrading conditions were attributable solely to electrical stunning. Poor neck cutting, too severe plucking and flapping of the wings before death also played a part.

Survival rate and carcase downgrading after the stunning of broilers with carbon dioxide-argon mixtures.

As chickens may rapidly regain consciousness after gas stunning, the effects of a two minute exposure to a carbon dioxide-argon mixture on survival rate were investigated. Broilers were stunned in batches of 10 per transport crate with a mixture of 10, 20 or 30 per cent carbon dioxide in argon with 5 per cent residual oxygen. The birds were exposed to the gaseous atmosphere for two minutes. A control group of birds was electrically stunned (120 mA for four seconds; 50Hz sinusoidal waveform). In addition, the incidence of carcase downgrading conditions after stunning with 20 per cent or 30 per cent carbon dioxide in argon with 5 per cent residual oxygen was compared with the incidence after electrical stunning. The results showed that stunning with 10 and 20 per cent carbon dioxide in argon with 5 per cent residual oxygen resulted in survival rates of 24 and 1 per cent, respectively. Stunning with 30 per cent carbon dioxide in argon with 5 per cent residual oxygen resulted in the death of all the broilers. Electrical stunning resulted in a significantly (P less than 0.001) larger number of broilers with breast muscle haemorrhaging and broken furculum and coracoid bones, whereas stunning with gas mixtures resulted in a significantly (P less than 0.001) higher incidence of broilers with damaged wing bones. Electrical stunning of broilers resulted in a significantly higher pH in the breast muscles 20 minutes post mortem than stunning with carbon dioxide-argon mixtures.(ABSTRACT TRUNCATED AT 250 WORDS)

Investigation of palpation as a method for determining the prevalence of keel and furculum damage in laying hens.

Old breaks of the keel and furculum were identified by palpation in 500 end-of-lay hens from 10 flocks housed in free-range and barn systems, and the results were compared with the results obtained by a full dissection and inspection. The method was considered to be sufficiently precise to be used as a diagnostic tool although people using it would need to be trained. The results obtained by dissection indicated that 50 to 78 per cent of the birds in the flocks had breaks of the furculum and keel, but no other breaks of bones were detected.

Cleanliness of broilers when they arrive at poultry processing plants.

An eight-point photographic scale from 1 (very clean) to 8 (very dirty) was used to assess the cleanliness of the plumage of 69,783 live broiler chickens delivered in 54 loads to three processing plants which were each visited in spring, summer and winter. There were considerable variations between the plants and between the visits, but most birds were given scores of 6 or 7. The average plant scores were 6.07, 6.56 and 6.84, which were associated with frequencies of birds with scores of 7 or more of approximately 38, 56 and 73 per cent. There was some indication that longer feed-withdrawal times of up to 10 hours were associated with dirtier birds.

Effect of husbandry system on broken bones and bone strength in hens.

The effects of rearing system, forced moulting and three different layer housing systems on broken bones and bone strength, were examined in hens at the end of lay. Weak bones and broken bones were more common in battery hens which had been reared to point of lay on deep litter rather than in cages. The incidence of old breaks was greater in perchery birds (14 per cent) than in tiered terrace birds (5 per cent), and there was also a difference between their incidence in two types of perchery design (17 per cent and 11 per cent). Moulting was associated with a transient decline in bone strength, followed by an increase in strength during the second lay.

Effect of catching method and lighting intensity on the prevalence of broken bones and on the ease of handling of end-of-lay hens.

Five catching methods were compared in terms of their effect on the proportion of battery hens which had bones broken when they were removed from battery cages. In addition the effect of tier, lighting intensity during lay and lighting intensity during handling on the prevalence of fractures at catching and on old fractures which occurred during lay was evaluated. Catching and removing hens by one leg from the cages resulted in 11 to 14 per cent of the birds acquiring a broken bone, whereas catching and removing each bird by two legs resulted in 5 per cent of the birds acquiring a freshly broken bone. Removing more than one bird at a time from the cage tended to cause more skeletal damage than removing them individually, and incorporating a wooden breast support slide over the feed trough had no effect on the prevalence of broken bones. Catching birds in the top tier of a three-tiered battery unit was more difficult than for the middle or bottom tiers. When the light intensity at catching was the same as that during lay birds were more difficult to catch than when the light intensity was changed, but the effects were insufficient to affect the prevalence of damage to the skeleton.