The objective of this thesis was to investigate the effect of age and feeding length on phytase efficacy in broiler chickens during the starter phase. Two studies were carried out to evaluate this objective.<br>Study 1 was a randomized complete block design with 4 × 5 factorial arrangements of treatments. There were four diets; a positive control (PC), negative control (NC) and two phytase supplemented diets with inclusion levels of 1,000 and 2,000 phytase units/kg. There were five age and duration of feeding groups; Three 2-d feeding lengths terminated at d 8, 14, and 22 (d 6 to 8, d 12 to 14, and d 20 to 22), a 5-d feeding length terminated at d 14 (d 9 to 14) and a 16-d feeding length terminated on d 22 (d 6 to 22). Growth performance and sample collections were collected at the end of each phase i.e. d 8, 14 and 22. There was a difference (P < 0.01) in weight gain, feed intake, and feed efficiency between birds fed the PC diets and birds fed the NC diets across all groups as birds on the NC diets had lower performance (P < 0.05) than birds on the PC diet. However, birds fed the phytase supplemented diets had higher (P < 0.05) growth performance compared with birds fed the NC diet across all groups. Similarly, phosphorus (P) and calcium (Ca) digestibility and retention of birds fed the NC were lower (P < 0.05) as compared with birds fed the PC diet while birds fed the phytase supplemented diets had higher mineral digestibility and retention (P < 0.05) compared with birds on the NC diet. Age effect was evaluated by comparing the performance of birds fed the experimental diets for 2 d until d 8, 14, and 22. Birds fed until d 14 had the highest impact of the NC diet on mineral utilization, and the largest improvement of phytase on mineral utilization as compared with birds fed until d 8 and 22. Similarly, when feeding length effect was considered, birds fed for a shorter period had greater response to phytase (P < 0.05) on nutrient utilization than birds fed for a longer period at d 14 and 22. Tibia ash was higher (P < 0.05) in birds fed phytase supplemented diets for a longer period (i.e. 16 d) compared with birds fed or 2 or 5 d. The results from this study observed that age and duration of feeding influenced phytase efficacy especially in younger birds fed for a short period. However, it could not be determined if feeding birds for a short period at different ages in the starter phase would have a similar effect.<br>In study 2, the effects of age and feeding low P diets to birds for a short period of time on phytase efficacy and super dosing were evaluated at two critical points in the starter phase. This study had 3 × 2 × 2 factorial arrangements of treatments comprising 3 diets; a PC, NC, and a NC with phytase supplemented at 2,000 phytase units/kg; and 2 ages (i.e d 14 and 22) and 2 feeding lengths (i.e 2-d and 5-d). Thus, birds were fed the experimental diets from d 12 to 14, 9 to 14, 20 to 22, and 17 to 22 respectively. Results observed were similar to the first study. Birds fed the NC diet had lower (P < 0.01) performance as compared with birds fed the PC diets across all age and feeding length groups. Similarly, birds fed diets with the super dose level of phytase had greater growth performance (P < 0.01) compared with birds fed the NC diets. When age effect was considered, birds fed for 2 or 5 d until d 14 had the greatest improvements of phytase on nutrient utilization and bone mineralization compared with birds fed for both periods until d 22. When effect of feeding was considered, birds fed for 2-d at both ages had greater responses to phytase in performance and nutrient utilization compared with birds fed for 5-d at both ages. Plasma myo-inositol was higher (P < 0.01) in birds fed the super dose level of phytase compared with birds fed the NC diet.<br>In summary, we could conclude that the efficacy of phytase both at 1,000 and 2,000 FTU/kg was higher in birds fed for 2 d until d 14 as compared with the other groups. This could potentially help in designing studies to evaluate new phytase products or for comparing the efficacy of phytase from various sources. Feeding broiler chickens during the suggested time phase would potentially reveal the maximum efficacy of the phytase product.<br>

<p>U okviru doktorske disertacije prikazani su rezultati ispitivanja razliĉitih tehnolo&scaron;kih postupaka u cilju prevencije nastanka o&scaron;tećenja tabanskih jastuĉića brojlerskih pilića. Istraţivanja su sprovedena u 4 ogleda i to u jednom u kome su vr&scaron;ena ispitivanja fiziĉko &ndash; hemijskih i higroskopnih osobina materijala koji se mogu koristiti kao prostirka, kao i tri biolo&scaron;ka ogleda koji su imali za cilj da ispitaju uticaj razliĉitih faktora na o&scaron;tećenja tabanskih jatuĉića kod brojlerskih pilića. Cilj biolo&scaron;kih ogleda je bio da odgovore na pitanje da li se razliĉitim tretmanima prostirke, primenom razliĉitih preparata i ishranom moţe uticati na prevenciju nastanka tabanskih lezija kod brojlerskih pilića. Pored toga, cilj ovih ogleda je bio da se utvrdi kako primenjene tehnologije utiĉu na proizvodne rezultate brojlera. Od fiziĉkih karakteristika materijala koji se mogu koristiti kao prostirka u tovu brojlera ispitivane su sposobnost vezivanja i otpu&scaron;tanja vode, a od hemijskih sadrţaj suve materije, sadrţaj sirovih vlakana kao i pojedine frakcije (NDF, ADF, hemiceluoza, celuloza i lignin). Biolo&scaron;ki ogledi su sprovedeni u objektima eksprimentalne farme (mikro ogled) i u proizvodnim uslovima (makro ogled). U biolo&scaron;kim ogledima kao prostirka je kori&scaron;ćena p&scaron;eniĉna slama, a tretmani kojima je poku&scaron;ano pobolj&scaron;anje njenih karakteristika su bili seckanje, kao i dodatak mikrobiolo&scaron;ko-enzimskog preparata (Micropan Complex&reg;) i lignina. Uticaj ishrane na o&scaron;tećenja tabanskih jastuĉića ispitivan je u biolo&scaron;kom ogledu, ishranom brojlerskih pilića sme&scaron;ama sa smanjenom energijom i dodavanjem enzima koji pobolj&scaron;ava varenje hrane. Kao rezultat uticaja pomenutih tretmana ispitivani su kvalitet prostirke (vlaga, pH i emisija amonijaka), proizvodnih parametri u tovu brojlera (telesna masa, uto&scaron;ak hrane, konverzija, mortalitet i proizvodni indeks), pona&scaron;anje brojlera, kao i nastanak i stepen o&scaron;tećenja tabanskih jastuĉića.<br />Ocena o&scaron;tećenja tabanskih jastuĉića je vr&scaron;ena makroskopski (primenom skale od 0-3, a u skladu sa zahvaćenom povr&scaron;inom) i mikroskopski, histolo&scaron;kom analizom koţe tabanskih jastuĉića. Rezultati ispitivanja fiziĉko-hemijskih karakteristika razliĉitih materijala pokazuju da p&scaron;eniĉna slama upija velike koliĉine vode, a usled niskog sadrţaja NDF slabo optu&scaron;ta vodu te shodno tome predstavlja lo&scaron; izbor za prostirku u pogledu nastanka o&scaron;tećenja tabanskih jastuĉića. MeĊutim, rezultati su pokazali da seckanje slame, kao tehnolo&scaron;ki postupak, moţe uticati na nastanak i stepen o&scaron;tećenja tabanskih jastiĉića, ali da dovodi i do povećanja telesnih masa brojlera kao i promena u pona&scaron;anju pilića. Dodatak mikrobiolo&scaron;ko-enzimskog preparata dovodi do smanjenja pojave i stepena o&scaron;tećenja tabanskih jastuĉića brojlera gajenih i na seckanoj i na nesckanoj slami. Rezultati takoĊe pokazuju da se, u proizvodnim uslovima, primenom lignina u<br />prostirci od neseckane slame moţe smanjiti o&scaron;tećenje tabanskih jastuĉića. Upotreba sme&scaron;a koje sadrţe smanjene koliĉine energije uz primenu enzima dovodi do prevencije u pogledu nastanka tabanskih lezija, bez znaĉajnog uticaja na proizvodne rezultate. Histolo&scaron;ka analiza tabanskih jastuĉića je pokazala da sistem ocenjivanja koji se zasniva na zahvaćenoj povr&scaron;ini tabanskih jastuĉića u saglasnosti sa stepenom i ozbiljno&scaron;ću o&scaron;tećenja koţe tabanskih jastuĉića i da moţe predstavljati standardi model za ocenjivanje na liniji klanja. Na osnovu rezultata ove disertacije se moţe zakljuĉiti da primenjeni tehnolo&scaron;ki postupci mogu znaĉajno uticati na prevenciju o&scaron;tećenja tabanskih jastuĉića, bez negativnog uticaja na proizvodne rezultate u tovu brojlera.</p> / <p>Within this dissertation, the results of various technological processes are shown in order to prevent the occurrence of damage to the foot pads of broiler chickens. The study was conducted in four trials, one in which we investigated the physical - chemical and hygroscopic properties of materials that can be used as litter, as well as three biological trials which were aimed to examine the influence of various factors on the damage to the foot pads in broiler chickens. The objective of the biological experiments was to answer the question whether the various treatments of litters, usage of different preparations and nutrition can prevent occurrence of foot lesions in broiler chickens. In addition, the aim of this experiment was to determine how the applied technology affects performance of broiler chickens. Among physical properties of materials that can be used as litter in fatting broilers, absorption and release of water were investigate, and among chemical properties there were content of dry matter, crude fiber content as well as individual fractions (NDF, ADF, hemicelluloses, cellulose and lignin). Biological experiments were conducted in the facilities of experimental farm (micro experiment) and in production conditions (macro experiment). In biological experiments wheat straw was used as litter and treatments which attempted to improve its characteristics were chopping and addition of microbial-enzyme preparation (Micropan Complex&reg;) and lignin. Feeding influence on damage to the foot pad was tested in a biological experiment, by feeding broilers with reduced energy diet and by adding enzymes that improve digestion. As a result of the impact of the above mentioned treatments there were tested the litter quality (moisture, pH and ammonia emissions), production parameters in fattening broilers (body weight, feed consumption, conversion, mortality and production index), the behavior of broilers, as well as the onset and degree of damage to the foot pads.<br />Assessment of the damage to the foot pads was done macroscopically (on a scale from 0-3, and according to the affected area) and microscopically, by histological analysis of skin of foot pads. Test results of physic-chemical characteristics of different materials indicate that wheat straw absorbs large amounts of water, due to the low content of NDF it releases water slowly and consequently represents a bad choice for a litter in terms of damage to the foot pads. However, the results showed that chopping straw as a technological procedure may influence the onset and degree of damage to the foot pads, but it also leads to an increase in body weight of broilers as well as changes in their behavior. Addition of microbial-enzyme preparation leads to a decrease in the occurrence and level of damage to the foot pads in broilers grown on both chopped and unchopped straw. The results have also shown that, under production conditions, using lignin in<br />the unchopped straw litter it can reduce the damage to the foot pads. The use of mixtures containing a reduced amount of energy with the use of the enzyme leads to prevention in terms of occurrence of foot lesions, without significant impact on performance. Histological analysis of foot pads have showed that the grading system that is based on the affected area of foot pads in accordance with the extent and severity of damage of the skin of foot pads and that it can represent a model for the assessment of standards on the slaughter line. Based on the results of this dissertation it can be concluded that the applied technological procedures can significantly influence the prevention ofdamage to the foot pads, with no negative impact on production results in fattening broilers.</p>

A series of seven experiments were conducted to evaluate the risk of acute (sudden death syndrome; SDS) or chronic (congestive heart failure; CHF) heart failure associated with dietary over-supplementation of vitamin A, vitamin D3, vitamin E, vitamin C or cardiotoxic factors present in meat meal. The risk of heart failure associated with the above mentioned dietary factors was tested followed by gross, microscopic, ultrastructural and biochemical investigation for mechanisms associated with mentioned risk factors. Simultaneously, the molecular mechanisms underlying the deterioration of heart function in fast-growing commercial broilers were studied. Each compound was tested separately at a concentration higher than the recommended levels. The basic experimental unit comprised groups of 40 to 50 day old male broiler chickens at the start of experiment. Lowered thermal brooding temperature protocol, an approach resulting in clinical manifestation of heart failure in practically all broilers predisposed to heart disease, was used.<p> Broilers fed the vitamin D3 enriched diet were 2.5 fold more likely to succumb to acute heart failure (p<0.05). Simulated stress challenge with epinephrine revealed that broilers fed excess of vitamin D3 were more susceptible to ventricular arrhythmia. The risk of CHF was higher (P<0.05) in broilers fed the vitamin D3, vitamin A and methanol soluble extract from meat meal enriched diets as compared to groups fed the control diet. The incidence of CHF in broilers fed the diet fortified with vitamin E was not significantly different as compared to the control group, whereas supplementation of vitamin C in the diet tended (p=0.10) to reduce the incidence of CHF. The level of malondialdehyde equivalents, an indicator of lipid peroxidation, was significantly higher (p<0.05) in myocardium of broilers developing CHF irrespective of dietary factors. Antioxidant vitamins (E and C) did not prevent lipid peroxidation in broilers developing CHF. <p>In conclusion, the present findings indicate that over-supplementation of vitamin A and D3 increases the risk of heart failure in broilers. Meat meal contains some unknown cardiotoxic factors, capable of precipitating heart conditions in susceptible broilers. Oxidative stress is involved in the pathogenesis of heart failure in broilers, but supplementation of antioxidant vitamins did not prevent oxidative damage in broilers that developed CHF. The oversupplementation of vitamins (A and D3) should not be encouraged in broilers diet as they may increase the economic losses to broilers industry subsequent to heart related mortalities/morbidities.

A series of trials were conducted to determine the effect of feeding barley silage to laying hens and broiler breeder pullets on performance, stress and behaviour. In the first study, two trials were conducted each with 20 hens and 2 roosters (n=176) randomly assigned to one of 8 community cages. The birds in 4 cages were provided with a nutritionally balanced soy/wheatbased laying hen diet ad libitum, whereas the birds in another 4 cages were given free access to barley silage in addition to the regular laying hen diet. In both trials, the control birds consumed more feed (P < 0.05) than the birds given barley silage. Birds fed barley silage had significantly decreased (P < 0.05) aggressive and feather pecking behaviours as well as time spent in their nest boxes at different ages. Time spent drinking, resting, preening and eating a large particle calcium source was similar between the two treatments. No treatment effects (P > 0.05) were found in regards to egg quality, egg production and bird weights at various ages; however yolk colour was darker by silage treatment in each trial. At the end of each trial, the feather score was improved in silage-fed birds compared to the control birds. It was concluded that feeding barley silage as a supplement to laying hens can improve their welfare without negatively affecting the egg production and egg quality. <p>A second study was conducted to determine the effect of feeding barley silage on body weight, stereotypic behaviour, stress and fear on broiler breeder pullets during the brooding and rearing periods. The 3 week old broiler breeder pullets (n=180) were randomly allocated into 12 straw litter floor pens having 15 birds per pen. The birds in 6 pens were provided with a nutritionally balanced corn/oat-soybean/canola meal-based broiler breeder diet at recommended restricted levels, whereas the birds in another 6 pens were given free access to barley silage in addition to a regular broiler breeder diet. Total DM intake was significantly higher (P < 0.05) for silage-fed birds compared to their control counterparts without affecting mean body weights. Dietary treatment had no significant effect on bird behaviour with the exception of object pecking behaviour which was reduced with silage feeding. Aggressive and gentle feather pecking behaviour was consistently numerically higher in the control birds than the silage-fed birds, although not significantly. Age affected many of the behaviours recorded in this study. Silage feeding had no significant effect on heterophil to lymphocyte ratios and tonic immobility values indicating that birds in both treatments were not very stressed or fearful. It was concluded that feeding barley silage to broiler breeder pullets has potential to aid in improving their welfare.

Two trials were conducted with the objective of investigating the effect of light intensity, approximately within the practical levels at confinement barns (1, 10, 20 and 40 lx), on production, processing characteristics and welfare of broilers raised to 35 d of age. In each trial, 950 Ross x Ross 308 chicks were placed randomly in each room with replication of individual light intensity treatment in two environmentally controlled experimental rooms. Within each large room, a small pen with 25 male and 25 female chicks was used for recording behaviour. Data were analyzed as a randomized complete block design, considering trial as a block. All chicks were exposed to 40 lx light intensity and 23 h light for the first 7 d, followed by treatment light intensity and 17 h day length thereafter. Body weight and feed consumption were determined at 7, 14, and 35 d of age. At the conclusion of each trial, 60 birds per treatment were processed to determine the detailed meat yield. For each replicate, behaviour was recorded for the 24 h period, starting at 16 or 17 d of age. At 23 d of age, serum samples were collected from three birds per room at the start, middle and end of light and dark periods, respectively, for melatonin estimation. Skeletal and foot pad, and ocular health were monitored at 31 and 32 d of age, respectively. Broiler live production (BW, FC, FCR and mortality) was unaffected by light intensity. Carcass, thigh and drum yield as a percentage of live weight decreased linearly with increasing light intensity. The 1 lx treatment resulted in heavier wings as a percentage of live weight. Birds exposed to 1 lx rested more and had reduced expression of foraging, preening, dust-bathing, stretching and wing-flapping behaviours in comparison to other light intensities, over the 24 h period and 17 h light phase. Light intensity did not affect circadian behavioural rhythms (24 h period) and behavioural patterns over the 17 h light phase. Diurnal rhythms of serum melatonin were also unaffected by light intensity with all treatments demonstrating a pronounced rhythm. Skeletal health was unaffected by light intensity but ulcerative foot pad lesions decreased linearly with increasing light intensity. Birds exposed to the 1 lx intensity had heavier and larger eyes. In conclusion, light intensity did not affect broiler production, behavioural and physiological rhythms and mortality but did affect carcass characteristics. Increased ulcerative foot pad lesions, ocular dimensions and altered behavioural expression at 1 lx light intensity are indicators of reduced broiler welfare.

Several studies were designed to investigate effect of cold winter transportation on broiler meat quality and physiological parameters. The first study assessed the effect of microclimate environment during winter transportation (-27 to +11ºC) from farm to the processing plant (3-4 h) on core body temperature (CBT) and breast meat quality parameters of 522 broiler chickens using an actively ventilated transport vehicle. Temperatures below freezing during transportation resulted in significantly (P < 0.05) higher ultimate pH (pHu) and darker color breast meat, which led to 8% incidence of dark, firm and dry (DFD) breast meat (pH > 6.1; L*< 46).<p> The effects of extreme cold conditions (-18 to -4ºC) along with age (5 and 6 wk), gender and lairage (0 and 2 h) on physiology parameters, breast muscle metabolites and meat quality of 360 birds using a simulated transport system were investigated. Five and 6 wk birds exposed to temperatures below -8 and -14ºC, respectively, showed significantly (P < 0.05) lower CBT and blood glucose and higher live shrink with breast meat that was darker in color, higher in pHu, water holding and water binding capacity compared to breast meat of birds exposed to warmer temperatures. A high incidence of DFD breast meat (> 50%) was observed for 5 and 6 wk birds exposed to temperatures below -8 and -14ºC respectively. Lairage following acute cold exposure caused an increase of up to 20% in DFD breast meat following exposure of the birds to temperatures below -8ºC.<p> Characteristics of cold-induced DFD breast meat were investigated in broiler chickens. DFD breast meat was significantly darker, redder, and less yellow in color and had higher pH, water binding capacity, processing cook yield and lower thaw and cook loss compared to normal meat. However, no significant difference in initial energy reserves was observed between DFD and normal breast meat.<p> Effect of extreme cold-stress (-15 to -9ºC) was further assessed on thigh meat quality and incidence of DFD from 160 male broilers. A greater impact of cold stress was observed on muscle metabolites and pH of thigh compared to breast meat, with 85% DFD incidence in thigh compared to 42% in breast meat of cold-stressed birds.<p> Biochemical basis of cold-induced DFD breast and thigh meat was investigated by measuring muscle metabolites at different times post-mortem. Lack of energy reserves at slaughter clearly explained the incidence of DFD thigh meat, but other factors might contribute to DFD breast meat aside from glycogen reserve at slaughter. However, the factors leading to DFD breast meat still remain unresolved and association of post-mortem enzyme activity and development of DFD breast meat merits further investigation.

Several studies were designed to investigate effect of cold winter transportation on broiler meat quality and physiological parameters. The first study assessed the effect of microclimate environment during winter transportation (-27 to +11ºC) from farm to the processing plant (3-4 h) on core body temperature (CBT) and breast meat quality parameters of 522 broiler chickens using an actively ventilated transport vehicle. Temperatures below freezing during transportation resulted in significantly (P < 0.05) higher ultimate pH (pHu) and darker color breast meat, which led to 8% incidence of dark, firm and dry (DFD) breast meat (pH > 6.1; L*< 46).<p> The effects of extreme cold conditions (-18 to -4ºC) along with age (5 and 6 wk), gender and lairage (0 and 2 h) on physiology parameters, breast muscle metabolites and meat quality of 360 birds using a simulated transport system were investigated. Five and 6 wk birds exposed to temperatures below -8 and -14ºC, respectively, showed significantly (P < 0.05) lower CBT and blood glucose and higher live shrink with breast meat that was darker in color, higher in pHu, water holding and water binding capacity compared to breast meat of birds exposed to warmer temperatures. A high incidence of DFD breast meat (> 50%) was observed for 5 and 6 wk birds exposed to temperatures below -8 and -14ºC respectively. Lairage following acute cold exposure caused an increase of up to 20% in DFD breast meat following exposure of the birds to temperatures below -8ºC.<p> Characteristics of cold-induced DFD breast meat were investigated in broiler chickens. DFD breast meat was significantly darker, redder, and less yellow in color and had higher pH, water binding capacity, processing cook yield and lower thaw and cook loss compared to normal meat. However, no significant difference in initial energy reserves was observed between DFD and normal breast meat.<p> Effect of extreme cold-stress (-15 to -9ºC) was further assessed on thigh meat quality and incidence of DFD from 160 male broilers. A greater impact of cold stress was observed on muscle metabolites and pH of thigh compared to breast meat, with 85% DFD incidence in thigh compared to 42% in breast meat of cold-stressed birds.<p> Biochemical basis of cold-induced DFD breast and thigh meat was investigated by measuring muscle metabolites at different times post-mortem. Lack of energy reserves at slaughter clearly explained the incidence of DFD thigh meat, but other factors might contribute to DFD breast meat aside from glycogen reserve at slaughter. However, the factors leading to DFD breast meat still remain unresolved and association of post-mortem enzyme activity and development of DFD breast meat merits further investigation.

A series of seven experiments were conducted to evaluate the risk of acute (sudden death syndrome; SDS) or chronic (congestive heart failure; CHF) heart failure associated with dietary over-supplementation of vitamin A, vitamin D3, vitamin E, vitamin C or cardiotoxic factors present in meat meal. The risk of heart failure associated with the above mentioned dietary factors was tested followed by gross, microscopic, ultrastructural and biochemical investigation for mechanisms associated with mentioned risk factors. Simultaneously, the molecular mechanisms underlying the deterioration of heart function in fast-growing commercial broilers were studied. Each compound was tested separately at a concentration higher than the recommended levels. The basic experimental unit comprised groups of 40 to 50 day old male broiler chickens at the start of experiment. Lowered thermal brooding temperature protocol, an approach resulting in clinical manifestation of heart failure in practically all broilers predisposed to heart disease, was used.<p> Broilers fed the vitamin D3 enriched diet were 2.5 fold more likely to succumb to acute heart failure (p<0.05). Simulated stress challenge with epinephrine revealed that broilers fed excess of vitamin D3 were more susceptible to ventricular arrhythmia. The risk of CHF was higher (P<0.05) in broilers fed the vitamin D3, vitamin A and methanol soluble extract from meat meal enriched diets as compared to groups fed the control diet. The incidence of CHF in broilers fed the diet fortified with vitamin E was not significantly different as compared to the control group, whereas supplementation of vitamin C in the diet tended (p=0.10) to reduce the incidence of CHF. The level of malondialdehyde equivalents, an indicator of lipid peroxidation, was significantly higher (p<0.05) in myocardium of broilers developing CHF irrespective of dietary factors. Antioxidant vitamins (E and C) did not prevent lipid peroxidation in broilers developing CHF. <p>In conclusion, the present findings indicate that over-supplementation of vitamin A and D3 increases the risk of heart failure in broilers. Meat meal contains some unknown cardiotoxic factors, capable of precipitating heart conditions in susceptible broilers. Oxidative stress is involved in the pathogenesis of heart failure in broilers, but supplementation of antioxidant vitamins did not prevent oxidative damage in broilers that developed CHF. The oversupplementation of vitamins (A and D3) should not be encouraged in broilers diet as they may increase the economic losses to broilers industry subsequent to heart related mortalities/morbidities.

A series of trials were conducted to determine the effect of feeding barley silage to laying hens and broiler breeder pullets on performance, stress and behaviour. In the first study, two trials were conducted each with 20 hens and 2 roosters (n=176) randomly assigned to one of 8 community cages. The birds in 4 cages were provided with a nutritionally balanced soy/wheatbased laying hen diet ad libitum, whereas the birds in another 4 cages were given free access to barley silage in addition to the regular laying hen diet. In both trials, the control birds consumed more feed (P < 0.05) than the birds given barley silage. Birds fed barley silage had significantly decreased (P < 0.05) aggressive and feather pecking behaviours as well as time spent in their nest boxes at different ages. Time spent drinking, resting, preening and eating a large particle calcium source was similar between the two treatments. No treatment effects (P > 0.05) were found in regards to egg quality, egg production and bird weights at various ages; however yolk colour was darker by silage treatment in each trial. At the end of each trial, the feather score was improved in silage-fed birds compared to the control birds. It was concluded that feeding barley silage as a supplement to laying hens can improve their welfare without negatively affecting the egg production and egg quality. <p>A second study was conducted to determine the effect of feeding barley silage on body weight, stereotypic behaviour, stress and fear on broiler breeder pullets during the brooding and rearing periods. The 3 week old broiler breeder pullets (n=180) were randomly allocated into 12 straw litter floor pens having 15 birds per pen. The birds in 6 pens were provided with a nutritionally balanced corn/oat-soybean/canola meal-based broiler breeder diet at recommended restricted levels, whereas the birds in another 6 pens were given free access to barley silage in addition to a regular broiler breeder diet. Total DM intake was significantly higher (P < 0.05) for silage-fed birds compared to their control counterparts without affecting mean body weights. Dietary treatment had no significant effect on bird behaviour with the exception of object pecking behaviour which was reduced with silage feeding. Aggressive and gentle feather pecking behaviour was consistently numerically higher in the control birds than the silage-fed birds, although not significantly. Age affected many of the behaviours recorded in this study. Silage feeding had no significant effect on heterophil to lymphocyte ratios and tonic immobility values indicating that birds in both treatments were not very stressed or fearful. It was concluded that feeding barley silage to broiler breeder pullets has potential to aid in improving their welfare.

Two trials were conducted with the objective of investigating the effect of light intensity, approximately within the practical levels at confinement barns (1, 10, 20 and 40 lx), on production, processing characteristics and welfare of broilers raised to 35 d of age. In each trial, 950 Ross x Ross 308 chicks were placed randomly in each room with replication of individual light intensity treatment in two environmentally controlled experimental rooms. Within each large room, a small pen with 25 male and 25 female chicks was used for recording behaviour. Data were analyzed as a randomized complete block design, considering trial as a block. All chicks were exposed to 40 lx light intensity and 23 h light for the first 7 d, followed by treatment light intensity and 17 h day length thereafter. Body weight and feed consumption were determined at 7, 14, and 35 d of age. At the conclusion of each trial, 60 birds per treatment were processed to determine the detailed meat yield. For each replicate, behaviour was recorded for the 24 h period, starting at 16 or 17 d of age. At 23 d of age, serum samples were collected from three birds per room at the start, middle and end of light and dark periods, respectively, for melatonin estimation. Skeletal and foot pad, and ocular health were monitored at 31 and 32 d of age, respectively. Broiler live production (BW, FC, FCR and mortality) was unaffected by light intensity. Carcass, thigh and drum yield as a percentage of live weight decreased linearly with increasing light intensity. The 1 lx treatment resulted in heavier wings as a percentage of live weight. Birds exposed to 1 lx rested more and had reduced expression of foraging, preening, dust-bathing, stretching and wing-flapping behaviours in comparison to other light intensities, over the 24 h period and 17 h light phase. Light intensity did not affect circadian behavioural rhythms (24 h period) and behavioural patterns over the 17 h light phase. Diurnal rhythms of serum melatonin were also unaffected by light intensity with all treatments demonstrating a pronounced rhythm. Skeletal health was unaffected by light intensity but ulcerative foot pad lesions decreased linearly with increasing light intensity. Birds exposed to the 1 lx intensity had heavier and larger eyes. In conclusion, light intensity did not affect broiler production, behavioural and physiological rhythms and mortality but did affect carcass characteristics. Increased ulcerative foot pad lesions, ocular dimensions and altered behavioural expression at 1 lx light intensity are indicators of reduced broiler welfare.