|Lay Jr, Donald|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2006
Publication Date: 2/15/2007
Citation: Toscano, M.J., Lay Jr, D.C., Craig, B.C., Pajor, E.A. 2007. Assessing the adaptation of swine to 57 hours of feed deprivation in terms of behavioral and physiological responses. Journal of Animal Science. 85:441-451.
Interpretive Summary: Hunger has been identified as a potential welfare issue in a variety of production situations including restricted feeding. Despite efforts to develop objective criteria that determine an animal’s welfare in these situations, the subjective nature of stress and the problems in quantifying the subjective experience (i.e., hunger) have made identifying animals with compromised welfare a difficult goal to achieve. If the hunger experienced by animals at particular deprivation lengths is linked with specific physiological and behavioral responses, it may offer unique means to assess the hunger that the animal is experiencing. Our results from this study offer a unique assessment of different gradations or levels of hunger. By including a wide array of measures, a broad picture that encompasses a range of responses and provides an objective framework to make assessments of welfare was created. However, before such a methodology can be adopted to evaluate the satiety effectiveness of diets, several key issues need to be resolved including the effectiveness of the controlled feeding regimen in satiating an animal in comparison to the fasted treatment, diurnal rhythms underlying behavioral patterns, and potential alternatives to purposely increasing hunger, i.e. providing graded levels of energy. Lastly, this methodology requires testing over various settings to determine the consistency of methods across such settings, i.e. acute versus chronic feed deprivation, growing pigs vs. mature sows, etc. These data provide researchers with a novel method to assist in developing diets which causes satiety.
Technical Abstract: Dramatic changes in the livestock industry have brought about widespread concern regarding the welfare of the animals cared for in terms of the hunger that they may experience. Despite this concern, animal science has not been able to provide a methodology that can objectively determine whether the welfare of the animals is compromised. The current work sought to develop a broad foundation of scientific data to determine when the adaptive capacity of an animal is overextended and welfare is compromised by a metabolic challenge and the resulting hunger. For this purpose, two separate experiments were conducted in which physiological or behavioral measures were collected from swine deprived of feed for 21 to 57 h (DEP) or fed normally (CON) (physiology, n = 20/trt; behavior, n = 8/trt). Proc Mixed of SAS was used to determine the effect of treatment and treatment by time interactions on the observed measures. Treatment x time interactions were found for glucagon (P = 0.03), insulin (P < 0.001), insulin:glucagon (P < 0.001), ß-hydroxybutyrate (P < 0.001), non-esterified fatty acids (P< 0.001), drinking (P = 0.002), standing (P = 0.01), inactivity (P = 0.02), lying sternal (P = 0.03), lying lateral (P = 0.002), and total lying (P = 0.004). Although the animals appeared to adjust appropriately to the metabolic challenge imposed as suggested by increases in alternative energy substrates, our results suggest that feed deprivation for durations greater than 45 h produced behavioral changes that may be related to increased sensations of hunger. These data provide objective measures which can be used in evaluating diets designed to create a greater level of satiety in sows.