Past Events

The objectives for this study included: (1) determining the optimum dose of biochar to reduce enteric methane (CH4) emissions from beef cows (EXP1) and (2) determining whether biochar (Oregon Biochar Solution, White City, OR) supplementation can reduce CH4 emissions from cows on pasture (EXP2). In EXP1, pregnant beef cows (n=8) were used in a replicated 4 × 4 Latin square study with biochar supplemented at 0, 1, 2, or 3% of dry matter intake (DMI).

The growth performance of broiler chickens has increased tremendously over the past 60 years due to improvements in nutrition, management strategies, and intense genetic selection. However, this increase in performance has been linked to undesirable conse-quences that affect the welfare and meat quality of fast-growing broiler chickens. Thus, there has been increasing interest in the use of slower-growing (SG) strains to mitigate problems associated with fast growth.

The sustainability and profitability of the dairy industry are at the forefront of current research. This is, in large part, due to increases in the costs of production and growing concern for the environmental impact of the dairy industry. Historically, traits related to improving feed efficiency have not been included in selection programs due to the high cost of phenotyping. With advancements in genomic selection and international collaboration including feed efficiency into selection, programs have become more feasible.

Sows’ milk as a sole source of nutrients limits growth of piglets and fails to habituate piglets to pellet-ed, plant-based post-weaning diets. The aim of this thesis was to evaluate pre- and post-weaning nu-tritional strategies on piglet growth performance, gut development, and immune response. First, with respect to creep feed composition and form, piglets provided liquid milk replacer had the greatest body weight at weaning. Between weaning and one-week post-weaning, pigs provided commercial creep feed had the greatest reduction in specific activity of maltase.

The gut microbiota is a key regulator of the neuroimmune and neuroendocrine communication pathways of the brain-gut-microbiota axis. Disruption of the microbiome can lead to deterioration in gastrointestinal, neuroendocrine, immune functioning and may even contribute to the etiology and course of some psychiatric disorders. Some enteric gut bacteria, such as Lactobacillus species, have demonstrable beneficial effects on health and disease. Consequently, these organisms are used as probiotic supple-ments.

This thesis investigated the use of low-complexity, corn- and soybean meal-based diets in the nursery and as-sessed the effects of deoxynivalenol (DON) contamination and the effects of supplementation with immunomodulatory feed additives, such as a commercial anti-mycotoxin feed additive or fish oil on pig growth performance, gastrointestinal tract morphology, and immune system robustness. In the first week after weaning, both low and high DON-contaminated low-complexity diets resulted in reduced average daily gain and feed intake compared to pigs fed a high-complexity diet.

The presence of stressors such as disease or heat stress can lead to negative economic impacts in animal production by creating additional costs to producers for management and medication, weakened productive performance, or increased mortality. Genetic improvement for resistance traits is permanent and cumulative and, therefore, a viable solution for these issues in animal production systems. This thesis focuses on gastrointestinal parasite resistance, genetic resistance to scrapie, and heat tolerance in sheep.

This thesis investigated the impact of complete replacement of inorganic sources of supplementary trace minerals by organic sources in the diet of transition cows on cellular and humoral immunity of dams and neonate calves, colostrum characteristics, and oxidative balance, health and growth of calves. In cows, neu-trophil function was assessed in vitro by flow cytometry assays, and acquired immunity was evaluated by in vivo IgG responses to ovalbumin.

The overall objective of this thesis was to determine how milk yield at dry-off in AMS-milked cows, as affected by milking frequency and feed supplement allocation in the AMS, impacted udder health over the dry period, and how those factors might also affect milk production and cow behaviour before dry-off and in the next lactation.