Amy Elizabeth Taylor

Background/Objectives: Lawsonia intracellularis is a bacterium that causes Proliferative Enteropathy, an enteric infection characterized mainly by diarrhea and growth retardation, leading to important economic losses. Acute and chronic infections are easily diagnosed, and their control by vaccination has been proven efficacious. However, subclinical infections, despite being very prevalent, often remain underdiagnosed and uncontrolled in practice. Scarce research is available on the control of subclinical infections by vaccination, and the benefit in these scenarios remains to be elucidated. Two field trials were carried out to (1) determine the association between the growth and fecal shedding of L. intracellularis in unvaccinated and intramuscularly vaccinated pigs in a farm with subclinical infection and (2) assess the impact of intradermal vaccination against L. intracellularis on clinical performance and carcass quality in a herd with subclinical infection. Methods: A pig herd with subclinical infection was selected. Pigs were vaccinated intramuscularly (study 1) or intradermally (study 2) at weaning. Fecal shedding, performance, clinical parameters, and carcass quality were investigated. Results: Growth was negatively associated with the fecal load of L. intracellularis in non-vaccinated pigs, whereas in vaccinated pigs, growth performance was not impacted by fecal load (study 1). Vaccinated pigs presented a significantly lower fecal load, lower prevalence of tail biting (31.7%) compared with controls (54.2%), less back fat, and a greater Lean Meat percentage (study 2). Conclusions: Vaccination against L. intracellularis in a herd with subclinical infection and low fecal bacterial shedding led to a reduction in fecal shedding, a lower prevalence of tail biting, and an improvement in carcass quality.

The proposed protocol is for a rapid evidence synthesis analysis into the use of livestock exclusion fencing as an on-farm intervention for improving water quality. The primary objectives are to assess the use of livestock exclusion fencing to improve water quality by reducing nutrient load, the presence of faecal indicator organisms and sediment load in watercourses on farms. The secondary objectives include evaluating how stocking density/land cover and watercourse size moderate the impacts of exclusion fencing on water quality. The protocol outlines the rationale and objects of the review, and the inclusion criteria, search strategy, data extraction, statistical analysis, risk of bias and data synthesis.

The proposed protocol is for a rapid evidence synthesis analysis into the use of livestock exclusion fencing as an on-farm intervention for improving water quality. The primary objectives are to assess the use of livestock exclusion fencing to improve water quality by reducing nutrient load, the presence of faecal indicator organisms and sediment load in watercourses on farms. The secondary objectives include evaluating how stocking density/land cover and watercourse size moderate the impacts of exclusion fencing on water quality. The protocol outlines the rationale and objects of the review, and the inclusion criteria, search strategy, data extraction, statistical analysis, risk of bias and data synthesis.

1. The aim of this study was to evaluate the effects of phytase and xylanase and their interaction on laying hen performance, egg quality, phosphorus (P) digestibility, phytate breakdown, volatile fatty acid (VFA) production and peptide YY concentration. 2. Two hundred and forty hens were allocated to cages at 22 weeks of age based on a 3 × 2 arrangement with phytase (0, 300 or 1500 FTU/kg) and xylanase (0 or 12 000 BXU/kg) as factors. 3. Phytase increased hen-day production (P < 0.05), daily egg mass (P < 0.05) and P digestibility with increasing levels of phytase (P < 0.001). Phytase fed at 1500 FTU/kg reduced IP6 and IP5 and increased myo-inositol concentration in gizzard digesta (P < 0.05). Phytase fed at 300 FTU/kg reduced IP6 in ileal digesta (P < 0.05); however, IP6 and IP5 were further reduced and myo-inositol increased when phytase was added at 1500 FTU/kg (P < 0.05). 4. Xylanase improved feed efficiency when phytase was fed at 300 FTU/kg (P < 0.05). In the absence of phytase, xylanase reduced dry matter and Ca digestibilities (P < 0.05). 5. Neither phytase nor xylanase had an effect on peptide YY or caecal VFA concentrations.

The aim of the current study was to evaluate the efficacy of Ronozyme HiPhos (DSM Nutritional Products Ltd.) in the immediate postweaning period and to determine the equivalency value of this phytase relative to P. A total of 568 mixed-sex pigs were weaned at 26.3 d (SD 1.01) of age and an average weight of 7.9 kg (SD 1.51). Pigs were offered 1 of 8 diets. Diets were fed from weaning for a period of 3 wk and consisted of a negative control (NC) diet containing 0.5% P, the NC diet + 0.05% P, the NC diet + 0.10% P, the NC diet + 0.15% P, the NC diet + 0.20% P, and the NC diet + 500, 1,000, or 2,000 phytase units (FYT)/kg. Increasing dietary P had no effect on ADFI or ADG; however, it did quadratically improve G:F (P < 0.05). Increasing levels of dietary phytase tended to increase ADG (linear, P = 0.056) and linearly improved G:F (P < 0.05). Increasing dietary P or adding phytase improved apparent total tract digestibility (ATTD) of P (linear, P < 0.001; quadratic, P < 0.05) and Ca (linear, P < 0.001; quadratic, P < 0.01). In conclusion, phytase was effective in improving performance and improving P and Ca ATTD of pigs during the immediate postweaning period. Based on ATTD of P, 500 FYT/kg was equivalent to the addition of 0.088% of P in weaner pig diets. Copyright © 2016. American Society of Animal Science .