Alternative Measures of Physiological Stress in Nursery Pigs and Broiler Chickens

Matthew Phillip Aardsma, Purdue University

Abstract

Farm animals face a variety of stressors during commercial production practices, and economic necessities and ethical considerations require mitigation strategies to help animals cope with stressors that might otherwise reduce animal performance or lead to morbidity. In swine production, arguably the most stressful period of a pig’s life is the first several weeks following weaning (nursery period), where pigs must rapidly adapt to a host of environmental and physiological stressors. In broiler chickens, exposure to environmental temperatures above their comfort zone is a considerable stressor. Accordingly, several studies were conducted with the objective of developing alternative ways to measure physiological stress in nursery pigs and broiler chickens. These alternative methods may improve the ability of animal scientists to measure physiological stress and thereby aid in development of mitigation strategies. Nursery pigs frequently struggle with diarrhea and other intestinal diseases characterized by increases in intestinal permeability. Therefore, several studies were conducted to evaluate the use of nonmetabolizable carbohydrates (lactulose and mannitol) as a non-invasive measure of intestinal health in weanling pigs. In Exp 2.1 and Exp 2.2, an aspirin-induced model of intestinal permeability was explored and the excretion pattern of lactulose and mannitol in urine over a 48 h urine collection period was determined. Aspirin at 15 mg/kg BW increased the excretion of lactulose over that of pigs given 0 or 30 mg/kg of aspirin, and therefore has potential to be used to induce intestinal permeability in nursery pigs. The excretion of lactulose and mannitol peaked at 4 h post-oral dose with a solution of lactulose and mannitol and was primarily complete by 8 h post-oral dose. In the few published reports of the lactulose and mannitol test of intestinal health in weanling pigs, the dose of lactulose and mannitol has varied considerably, raising questions as to the comparability of the results. Accordingly, in Exp 3.1, the impact of variation in the dose of lactulose and mannitol was explored, and pigs given the lowest dose at 0.2 g/kg BW lactulose and 0.02 g/kg BW mannitol had large numerical decreases in lactulose excretion warranting further investigation. Pigs in Exp 3.1 also demonstrated low urine recovery rates (50% successful urine collection averaged over the 3 urine collection time points) which were postulated to be due to the stresses associated with urine collection in metabolism cages combining with the stresses of weaning. Therefore, in Exp 3.2, an alternative urine collection procedure was developed that utilized a urine collection pad held in place by an elastic wrap. Results from Exp 3.2 with urine collected either by metabolism cages or via the urine collection pads indicated that the urine collection pad held promise as an alternative urine collection method that would not require the use of metabolism cages. Accordingly, the use of the collection pad was evaluated as part of a lactulose and mannitol test of intestinal health in group-housed nursery pigs in Exp 5.1. In brief, in Exp 5.1, pigs were weaned, transported for 12 h in a livestock trailer, and fed five treatment diets for 14 d post-weaning. The treatment diets were designed to evaluate the additive effects of L-glutamine and a combination of prebiotics and probiotics as potential antibiotic alternatives to aid in mitigating stress associated with weaning and transport.

Degree

Ph.D.

Advisors

Richert, Purdue University.

Subject Area

Surgery|Physiology|Animal sciences|Atmospheric sciences|Bioinformatics|Genetics|Medicine

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