No description available.

No description available.

No description available.

It is appreciated that improvements in feed form (FF) result in improved broiler performance. However, research has primarily focused on the finishing growth phase due to associated high feed consumption allowing the greatest opportunity to observe performance benefits. Due to lower feed volumes required in the starter growth phase, it may be more economical to improve FF in the starter phase if improvements in overall performance and processing characteristics are observed. Study 1 investigated the potential for interactive effects of high or low FF presented in each of three growth phases to influence broiler performance. These data demonstrated the potential for FF presented in the starter phase to interact with FF in the finisher phase influencing day (d) 46 ending body weight (BW). Due to starter FF impacting overall performance, this led to Study 2 which consisted of two experiments with the main objective of determining the optimal crumble particle size for improved starter (d 0-14) performance. Experiment 1 utilized 5 different crumble particle sizes ranging from 1202- 2172 µm; whereas Experiment 2 implemented 8 differing crumble particle sizes ranging from 1174- 3736 µm. These data demonstrated consistent improvements in feed conversion ratio (FCR) as crumble particle size increased, with improvements in BW gain being demonstrated in Experiment 2 for crumbles 2800 µm and larger. Due to associated performance benefits with large particle sizes, Study 3 examined the potential to feed pellets, in comparison to crumbles, at different qualities during the starter period. Additionally, two commonly used genetic strains were employed to determine if performance benefits due to FF and feed quality (FQ) would be similar among different strains. Lastly, common diets were fed following the starter phase to determine if benefits due to starter FF would translate to improved overall performance. Feed quality and FF interacted to influence d 18 BW and d 0-18 BW gain. Examining carryover effects, d 0-32 and 0-46 FCR were influenced by FF and FQ; whereas d 0-62 was not influenced. These data suggest that length of the growout should be considered for determining FQ and FF to present in the starter growth phase.

To better understand the digestive and absorptive capacities of the chick intestine so that we may feed diets that better meet the nutritional needs of the chick, it is important to understand how expression of nutrient transporter genes changes in response to various factors. A series of feeding trials were conducted to evaluate the dietary and developmental regulation of nutrient transporter mRNA abundance in the small intestine of two lines of broilers selected on corn-based (Line A) or wheat-based (Line B) diets. Abundance of mRNA was quantified in all experiments using real time PCR and the absolute quantification method. The objective of the first study was to investigate intestinal nutrient transporter and enzyme mRNA in Line A and B broilers at embryo day 18 and 20, day of hatch, and d 1, 3, 7, and 14 posthatch. Genes evaluated included the peptide transporter, PepT1, 10 AA transporters (rBAT, bo,+AT, ATBo,+, CAT1, CAT2, LAT1, y+LAT1, y+LAT2, BoAT and EAAT3), four sugar transporters (SGLT1, SGLT5, GLUT5, and GLUT2), and a digestive enzyme, APN. For PepT1, Line B had greater quantities of mRNA compared with Line A (P = 0.001), suggesting a greater capacity for absorption of AA as peptides. Levels of PepT1 mRNA were greatest in the duodenum (P < 0.05), whereas the abundances of SGLT1, GLUT5 and GLUT2 mRNA were greatest in the jejunum (P < 0.05). Abundances of EAAT3, bo,+AT, rBAT, BoAT, LAT1, CAT2, SGLT5 and APN mRNA were greatest in the ileum (P < 0.05). Quantities of PepT1, EAAT3, BoAT, SGLT1, GLUT5, and GLUT2 mRNA increased linearly (P < 0.01), while CAT1, CAT2, y+LAT1, and LAT1 mRNA decreased linearly (P < 0.05) with age. The objective of the second study was to evaluate the effect of dietary protein quality on intestinal peptide, AA, and glucose transporter, and digestive enzyme mRNA abundance in Line A and B broilers. At day of hatch (doh), chicks from both lines were randomly assigned to corn-based diets containing 24% crude protein (CP) with either soybean meal (SBM) or corn gluten meal (CGM) as the supplemental protein source, ad libitum. Groups of chicks from both lines were also assigned to the SBM diet at a quantity restricted to that consumed by the CGM group (SBM-RT). Abundance of PepT1, EAAT3, and GLUT2 mRNA was greater in Line B (P < 0.03), while APN and SGLT1 were greater in Line A (P < 0.04). When feed intake was equal (CGM vs restricted SBM), a greater abundance of PepT1 and bo,+AT mRNA was associated with the higher quality SBM (P < 0.04), while a greater abundance of EAAT3 and GLUT2 mRNA was associated with the lower quality CGM (P < 0.01). When feed intake was restricted (SBM vs SBM-RT), a greater abundance of PepT1 mRNA was associated with the restricted intake (P < 0.04). The objective of the third study was to determine the effect of dietary protein composition on mRNA abundance of peptide and AA transporters, and a digestive enzyme. From day 8 to day 15 posthatch, Line A and B broilers were fed equal amounts of 1 of 3 diets (24% CP). Dietary protein sources included whey protein concentrate (whey), a partial whey hydrolysate (hydro), or a mixture of free amino acids (AA) similar to the composition of whey. Intestine was collected at days 8, 9, 11, 13, and 15. Expression of all genes except LAT1 was greater (P < 0.05) in Line B compared with A. Abundance of PepT1, EAAT3, y+LAT2, CAT1, bo,+AT, and APN mRNA varied little across diets in Line A but for CAT1 mRNA was greatest (P = 0.005) in Line A birds that consumed the AA diet. Expression of these genes was greatest (P < 0.006) in Line B birds consuming the hydro diet. A greater (P < 0.05) age response of bo,+AT, EAAT3, CAT1, and APN mRNA was observed in birds consuming the hydro or AA diets relative to the whey diet. Results from these studies collectively demonstrate that nutrient transporter gene expression is responsive to a variety of factors, including developmental stage, dietary manipulation, and genetic selection. Information from these studies can be used to improve dietary formulation so that nutrient utilization is enhanced, resulting in improved growth of the broiler. / Ph. D.

The incubation period is crucial for development and overall quality of a chick. The selection for fast growing broilers has allowed the birds to reach market weight at a faster rate making the incubation period a larger portion of a broiler's life. A faster growth rate can lead to the release of more metabolic heat inside of the egg toward the second half of incubation because the embryo shifts to a homeothermic state. More heat being released into the incubator can cause the incubation temperature to rise if the incubator is not electronically regulated or cannot be ventilated properly due to malfunction. A high incubation temperature can impact the hatchability, growth, and development of the chick. This thesis provides a more in-depth analysis of the effects of high incubation temperature (37.5°C versus 39.5°C) on the developing small intestine and yolk sac, which provide the chick with nutrients posthatch and during embryogenesis. Studying these organs and mechanisms occurring during this time could potentially indicate why chicks from eggs subjected to a higher incubation temperature are not developing and growing properly. Chicks from eggs incubated at a higher temperature had lower body weights, lower hatchability and lower villus height in the duodenum, jejunum, and ileum. There were also differences seen in the depth of the crypt, which is the site for stem cells. Chicks from eggs incubated at a higher temperature had a lower crypt depth in the duodenum and jejunum. There was no difference in the expression of the intestinal stem cell marker olfactomedin 4 (Olfm4) and mucin 2, which is secreted by goblet cells and forms mucus. In the yolk sac, heat shock proteins (HSP) 70 and 90 were elevated at embryonic day 15, and HSP90 still remained elevated at embryonic day 17. Chicks from eggs incubated at a higher temperature showed greater expression of peptide transporter 1 and avian beta-defensin 10 mRNA at embryonic day 13. Even though small intestinal morphology was impacted early posthatch and expression of genes in the yolk sac were elevated at embryonic day 13, there does not seem to be a long-lasting effect on the development of the small intestine or the yolk sac. It is still important to study the impact of the incubation environment to understand the development and growth of the chicks and how different incubation factors can impact the overall hatchability and health of the chick. / Master of Science / The incubation period is crucial for development and overall quality of a chick. The selection for fast growing broilers has allowed the birds to reach market weight at a faster rate making the incubation period a larger portion of a broiler’s life. A faster growth rate can lead to the release of more metabolic heat inside of the egg toward the second half of incubation because the embryo shifts to a homeothermic state. More heat being released into the incubator can cause the incubation temperature to rise if the incubator is not electronically regulated or cannot be ventilated properly due to malfunction. A high incubation temperature can impact the hatchability, growth, and development of the chick. This thesis provides a more in-depth analysis of the effects of high incubation temperature (37.5°C versus 39.5°C) on the developing small intestine and yolk sac, which provide the chick with nutrients posthatch and during embryogenesis. Studying these organs and mechanisms occurring during this time could potentially indicate why chicks from eggs subjected to a higher incubation temperature are not developing and growing properly. Chicks from eggs incubated at a higher temperature had lower body weights, lower hatchability and lower villus height in the duodenum, jejunum, and ileum. There were also differences seen in the depth of the crypt, which is the site for stem cells. Chicks from eggs incubated at a higher temperature had a lower crypt depth in the duodenum and jejunum. There was no difference in the expression of the intestinal stem cell marker olfactomedin 4 (Olfm4) and mucin 2, which is secreted by goblet cells and forms mucus. In the yolk sac, heat shock proteins (HSP) 70 and 90 were elevated at embryonic day 15, and HSP90 still remained elevated at embryonic day 17. Chicks from eggs incubated at a higher temperature showed greater expression of peptide transporter 1 and avian beta-defensin 10 mRNA at embryonic day 13. Even though small intestinal morphology was impacted early posthatch and expression of genes in the yolk sac were elevated at embryonic day 13, there does not seem to be a long-lasting effect on the development of the small intestine or the yolk sac. It is still important to study the impact of the incubation environment to understand the development and growth of the chicks and how different incubation factors can impact the overall hatchability and health of the chick.

In commercial settings, broiler chickens and rainbow trout are housed in barren environments under high stocking densities, due to an emphasis on production efficiency. These monotonous housing conditions do not provide broilers or trout with the ability to perform functional, highly-motivated behaviors and increase their susceptibility to excessive anxiety and fear, resulting in negative affective states and poor animal welfare. Affective state (or emotional state) is a cumulative product of short-term life experiences, ranging from positive to negative. Because affective states are largely influenced by environmental condition, determining animal affective state can provide useful information on how to improve housing conditions in order to ensure positive experiences and good animal welfare. Cognitive processes are closely associated with affective state; a "cognitive bias" occurs when affective state influences aspects of cognition, such as judgement and attention. Animals in positive affective states make optimistically-biased decisions during ambiguous situations, judging the situation as if it will produce a positive outcome, and show less bias towards a perceived threat, responding in a less anxious and calm manner. Animals in negative affective states make pessimistically-biased decisions during ambiguous situations, judging the situation as if it will result in a negative outcome. Additionally, animals in negative affective states will bias their attention towards a perceived threat rather than alternative stimuli, responding in an anxious manner. Therefore, judgement and attention bias tests can be used to determine animal affective states. In Chapter 3, a judgement bias test was used to determine affective state of broiler chickens housed in either complex (perches, dust bath, pecking stones, and rotating enrichment objects) or barren (no enrichment) environments under either high or low stocking densities. Broilers housed in complex environments responded more optimistically during the judgement bias test than broilers from barren environments, indicating the former were in a positive affective state. Stocking density did not impact their responses in the judgement bias test, indicating that affective states were not impacted by that treatment. In Chapter 4, an attention bias test was used to determine level of anxiety and a tonic immobility test was used to determine fear in order to investigate affective state of broilers housed in the same conditions as described for Chapter 3. Broilers housed in complex environments were less anxious during the attention bias test than broilers from barren environments, indicating environmental complexity reduced anxiety in broilers. Stocking density did not impact anxiety. Broilers from high stocking density environments had shorter tonic immobility durations than broilers from low stocking density environments, suggesting the former were less fearful. Environmental complexity did not impact fearfulness. In Chapter 5, a judgement bias test was used to determine affective state of rainbow trout housed in either complex (shelter structure and artificial plants) or barren (no enrichment) tanks under either low or high stocking densities. Trout housed in high stocking density tanks responded optimistically during the judgement bias test, indicating they were in a more positive affective state compared to trout housed in low stocking density tanks. Environmental complexity did not impact their responses in the judgement bias test, indicating no effect of enrichments on affective states was found. These results indicate a beneficial relationship of a complex environment on broiler chicken affective state, observed through an optimistic judgement bias and reduced attention bias (anxiety) towards a perceived threat. Thus, providing a complex housing environment for broilers can improve their welfare and result in a positive affective state. Rainbow trout reared at the tested high density resulted in a positive affective state, although complexity did not benefit their welfare. Our results contribute much needed information on stocking densities to ensure fish welfare. Overall, environmental complexity, not stocking density, had a positive impact on broiler chicken affective states. Rainbow trout affective states were positively impacted by stocking density, but not environmental complexity. / Master of Science / Conventional housing of broiler chickens and rainbow trout (both raised for meat) causes concern for their welfare and affective states. Environmental conditions can greatly impact animals' affective states–their long-term emotional state, ranging from positive to negative. In barren environments at high stocking densities, broiler chickens and rainbow trout are prevented from showing normal behaviors and these conditions can compromise their affective state and welfare. By 'asking' chickens and trout whether the glass is half full or half empty, we can determine level of optimism or pessimism, and level of anxiety or calmness, therefore gaining a better understanding of their affective states. This can be done using a judgement bias test and attention bias test, where animal responses (optimism and anxiety) are recorded during ambiguous situations (judgement) and threatening situations (attention). Animals in positive affective states judge ambiguous situations optimistically (glass half full) and pay little attention towards perceived threats, while animals in negative affective states judge the same ambiguous situations pessimistically (glass half empty) and pay more attention towards perceived threats. In Chapter 3, responses to ambiguous situations were used to determine the affective state of broiler chickens housed in either enriched (perches, dust bath, pecking stones, rotating toys) or barren environments at either high or low stocking densities. Broiler chickens housed in enriched environments had an optimistic judgement bias of ambiguous situations (glass half full), suggesting they were in a more positive affective state compared to broilers housed in barren environments. Stocking density did not impact their level of optimism. In Chapter 4, responses to a perceived threat were used to determine level of anxiety and a tonic immobility test was used to determine fear of broilers housed under the same conditions as in Chapter 3. Broilers housed in enriched environments paid less attention to a perceived threat than broilers housed in barren environments, indicating the former were less anxious (glass half full) and in a positive affective state. Fear was not impacted by the tested enrichments, but birds kept under higher stocking densities did show reduced fear compared to birds in low-density environments. In Chapter 5, rainbow trout were housed in either enriched (shelter structure and artificial plants) or barren tanks at either high or low stocking densities. Affective state was evaluated through their responses to ambiguous situations. Trout housed in high stocking density environments had an optimistic judgement bias of ambiguous situations (glass half full), suggesting they were in a more positive affective state than trout housed in low stocking density environments. The enrichments did not impact their responses during the test, suggesting they did not impact fish optimism. These results indicate that an enriched environment improves broiler affective state and welfare compared to conventional housing conditions, the tested densities did not impact their welfare. Although an enriched environment did not positively impact responses of trout during ambiguous situations, our results show that housing rainbow trout in large groups results in a positive affective state and improved welfare status compared to housing trout in small groups. Overall, environmental enrichment, not stocking density, had a positive impact on broiler chicken affective states. Rainbow trout affective states were positively impacted by stocking density, but not environmental enrichment.

Conventional housing environments for broiler chickens and commercial laying hens are often barren, high-density environments with an emphasis on production efficiency. These housing conditions limit birds' ability to display species-specific behaviors, can negatively impact health, and may contribute to negative cumulative experience. Cumulative experience is the culmination of all positive and negative experienced during an animal's lifetime. However, cumulative experience is difficult to quantify, as no validated measures of cumulative experience exist. Additionally, existing measures of negative animal experience mostly rely on interpretations of animal behavior which can be subjective, time consuming, and difficult to interpret. Therefore, there is scientific need for objective measures that can detect cumulative experience in poultry. Secretory and plasma Immunoglobulin A (IgA), telomere length, feather corticosterone concentrations, and attention bias testing all seem to respond to positive and negative experiences in humans or other non-human animal species, indicating that they may be useful as measures for poultry. Therefore, the objective of this thesis was to determine if these novel measures could be used as indicators of cumulative experience in broiler chickens and laying hens. In chapter 3, secretory and plasma IgA concentrations were measured in broilers raised in either high-complexity or low-complexity environments under either high or low stocking density over three replicated experiments. Birds housed in highly complex environments showed higher concentrations of plasma IgA compared to birds housed in low-complexity environments at day 48 of age, indicating reduced chronic stress in the former. Additionally, day 48 secretory IgA concentrations were decreased in birds housed in high-density environments compared to birds housed in low density environments, indicating birds from high-density environments were more chronically stressed. In chapter 4, gonad and kidney telomere length was measured to determine cumulative experience in broilers raised in the same housing conditions and replicated experiments of chapter 3. Treatment did not impact gonad telomere length, in line with expectations as gonads contain stem cells which produce high concentrations of telomerase. Birds housed in high-complexity pens had longer kidney telomeres compared to birds in low-complexity pens, indicating high-complexity birds had more positive cumulative experience. Stocking density did not impact kidney telomere length. In chapter 5, attention bias, tonic immobility, plasma and secretory IgA concentrations, and feather corticosterone concentrations were determined in laying hens raised in conventional cages or enriched floor pens. Birds in enriched floor pens showed increased attention bias, decreased tonic immobility, increased secretory IgA concentrations at week 22 of age, and decreased feather corticosterone concentrations compared to caged hens. These results indicate that compared to conventional cages, enriched pens in this study improved immune systems, reduced chronic stress, reduced fear, but increased anxiety in hens. In conclusion, secretory and plasma IgA and telomere length show appropriate contrast in response to broiler chicken housing conditions. However, additional work needs to be done before these measures can be widely used as measures of cumulative experience in poultry. Furthermore, attention bias, secretory IgA, and feather corticosterone showed an appropriate contrast between chronic stress responses in laying hens, but confirmation is needed in other contexts. Overall, the results indicate a beneficial relationship between environmental complexity and poultry welfare physiology and affective state, with the exception for anxiety in laying hens. Thus, providing an enriched environment can improve the welfare of commercial poultry and result in positive cumulative experience in most situations. Additionally, these results indicate that stocking density is a negative environment in broilers but potentially less intense than previously thought under experimental conditions. The assessment of behavioral and physiological measures of cumulative and positive animal experience should be included in experiments seeking to determine the impacts of environmental or management conditions to determine the broader impacts on poultry welfare. / Doctor of Philosophy / Conventional housing systems of broiler chickens (raised for meat) and laying hens (raised for egg production) can negatively impact their welfare. Animal welfare, defined as an animal's ability to interact with and cope with their environment, is an individual experience for each animal and fluctuates on a scale from very negative to very positive. Traditionally, measurements of animal welfare have focused only on avoiding the negative aspects of animal welfare such as fear, distress (negative stress), hunger, thirst, pain, and suffering. However, it is important that animals are provided opportunities to experience positive animal welfare to provide a life worth living. So, when measuring animal welfare, all positive and negative experiences (termed cumulative experience) should be included to form an accurate picture of an animal's welfare. However, no validated measures of cumulative experience exist in non-human animals. However, recently, several potential measures of cumulative experience have been proposed in human and non-human animals including secretory and plasma IgA, telomere length, feather corticosterone, and attention bias testing. So, the objective of this thesis was to determine if these proposed measures can be used to determine cumulative experience in commercial broilers and laying hens. In chapters 3 and 4, we investigated if secretory and plasma IgA concentrations (measure of chronic stress; chapter 3) and telomere length (measure of cumulative experience; chapter 4) responded to environmental complexity (positive stimulus) and stocking density (negative stimulus) over three replicated experiments. Broilers were housed in a 2 × 2 factorial study of either high or low complexity or high or low density. This resulted in four treatment groups of high-complexity/high-density, low-complexity/low-density, high-complexity/low-density, and low-complexity/high-density. During chapter 3, environmental complexity increased concentrations of plasma IgA, indicating that birds from high-complexity pens were under less chronic stress compared to birds from low-complexity pens. Alternatively, high density decreased secretory IgA, indicating that birds from high-density pens were under a more chronic stress than birds from low density pens. In chapter 4, environmental complexity increased telomere length in broilers compared to low-complexity pens indicating that environmental complexity positively impacted cumulative experience. However, stocking density did not impact telomere length, indicating that high density did not negatively impact cumulative experience. In chapter 5, we investigated if attention bias (measure of anxiety), tonic immobility duration (measure of fear), plasma and secretory IgA (chronic stress), and feather corticosterone (chronic stress) responded to environmentally enriched floor pens (positive housing system) and conventional caging (negative housing system). We found that birds housed in enriched floor pens were more anxious (increased attention bias), less fearful (decreased tonic immobility duration), and less chronically stressed (increased SIgA concentrations at week 22 and increased feather corticosterone concentrations) compared to birds housed in conventional cages. Overall, IgA concentrations and telomere length (broilers) and attention bias, secretory IgA concentration, and feather corticosterone concentrations (layers) seem useable as measures of animal experience in commercial poultry. Additionally, these results indicate that positive experience has a positive impact on cumulative experience in commercial poultry. Stocking density also seems to contribute to chronic stress in broilers, indicated by decreased SIgA concentrations, but only during the last few weeks of life. These findings should be confirmed by additional studies before common use as measures of cumulative experience in animals. However, the inclusion of measures of cumulative and positive animal experience should be included in experiment which wish to determine the broad impacts of housing system on non-human animals.

Some cattle producers have reported metabolic disturbances in beef cows fed high levels of broiler litter. Therefore, an experiment was conducted to evaluate mineral metabolism of beef cows fed different levels of broiler litter. Sixty Angus-Hereford crossbred cows ranging in age from 3 to 12 yr were blocked by age, BW, and stage of gestation, and randomly allotted within blocks to three diets: 1) mixed hay, full-fed; 2) 4.1 kg of a mixture of 80% broiler litter and 20% cornmeal plus mixed hay (low-litter diet); and 3) 8.2 kg of the 80% litter and 20% cornmeal mixture plus mixed hay (high-litter diet). Cows fed the litter diets were fed 57 g of magnesium oxide per head per day in the litter-corn mixture. Cows fed the three diets had access to a high-Mg mineral mixture. Experimental diets were fed from January 4, 1995 to April 19, 1995, and calving began on March 15. There were no physical signs of metabolic disturbances in any of the cattle. Blood serum Ca decreased and P levels increased in the cows fed both levels of broiler litter after the first 28 d on experiment. On d 28, average serum Ca values were 8.5 mg / dL for the cows fed hay, compared to 7.9 and 7.6 mg / dL for those fed the low and high levels of litter, respectively (P < .01). The average serum P values were 5.7, 8.2, and 9.1 mg/dL, respectively (P < .01). Generally, serum Ca remained lower and serum P remained higher for the cows fed broiler litter until the end of the winter feeding period (105 d). By mid-summer, serum Ca and P were similar (P > .05) for cows that had been fed the three diets. Serum Mg, Cu, and Zn were not affected by feeding litter. Urinary Ca and Mg, expressed as units per unit of creatinine, did not differ (P > .05) among treatments. Serum parathyroid hormone (PTH) was higher (P < .05) in cows fed the lower level of litter than those fed the higher level in April (105 d). Serum PTH values for cows fed hay were intermediate. Birth weights, rate of gain, and weaning weights of calves did not differ among the three diets. Feeding high levels of broiler litter to beef cows appears to affect serum Ca and P. / Master of Science

Traditional plating methods for bacterial enumeration can be limited, but the development of high-throughput DNA sequencing, such as Oxford Nanopore Technologies (ONT), can provide rapid and highly specific alternative for species-level identification. In this study, ONT amplicon sequencing was applied to fresh broiler breast meat to identify their bacterial composition and monitor their dynamic changes. The sequencing data were complemented by sensory panels, physicochemical analysis, and traditional plating methods. Over time, the bacterial diversity decreased within and across samples. By the end of shelf-life, Pseudomonas fragi, Pseudomonas lundesis, and Brochothrix thermosphacta became the most prevalent species. These bacteria were associated with spoilage attributes that were reported in the sensory panels. This study demonstrated the effectiveness of Nanopore sequencing in determining the spoilage associated bacteria in chicken meat. Future research may focus on developing targeted interventions to mitigate the impact of these spoilage bacteria and extend the shelf life of chicken meat.