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Strategically enriching the environment of zoo felids to encourage innate behaviors is essential to good welfare. To investigate how engagement differs among sensory-based enrichment, six items representing tactile (firehose log, Jolly Eggs), visual (mirror, movie), and olfactory (cinnamon, cologne) sensory categories were offered to three adult cheetah siblings. Each item was offered four times: twice during daytime hours and twice overnight (≥5 h/occasion). Static video monitoring was used to investigate engagement frequency and duration for each item and to observe grooming behaviors. Cheetahs engaged with visual enrichment more frequently (p < 0.05) and for greater (p < 0.05) periods than other items. Allogrooming occurred most frequently (p < 0.05) when the movie was provisioned at night. Tactile enrichment was only modestly engaged, with fewer but longer engagements (p < 0.05) at nighttime than at daytime. Autogrooming frequency did not vary among enrichment items but was greater (p < 0.05) at night than day. These findings showed that zoo cheetah responses to sensory enrichment items differed based on type and time of day. Visual stimuli were favored, whereas olfactory stimuli were generally ignored. This illustrates the benefit of diverse sensory-specific enrichment strategies. Such dynamic strategies can help overcome the challenge of individual preferences to encourage engagement reflective of the animal’s natural behaviors.

Zoological institutions, which were once exclusively for entertainment, are now leaders of wildlife conservation. This centuries-long transition was punctuated by key milestones that reformed wild animal exploitation into a mission of protection. Modern zoos perform ex situ activities to preserve natural resources, which are enabled by the housing of wild species. Zoo-managed animals facilitate new scientific knowledge, public education, and strategic breeding to maintain genetic diversity. Prioritizing animal welfare management is a key advancement for modern zoos, as it lessens stress and improves quality of life. Environments enriched with sensory stimuli promote naturalistic behaviors and provide opportunities for instinctual activities like foraging and hunting. This increases resiliency by reducing stress and boredom. However, such approaches only benefit welfare when appropriately matched to the animal. Behavioral responses to environmental cues reflect how animals experience their environment, and properly documenting them informs management decisions. Other modern advancements include enclosure designs, research initiatives, public education programs, species-specific staff training, and collaborative population management among zoos. This review chronicles the milestones that shaped the role of modern zoological institutions in species and habitat preservation. It also discusses opportunities for the continued evolution of welfare management practices, which is fundamental information for zoo employees and stakeholders.

For giraffes, few standardized methods exist for quantifying chronic stress. Allostatic load index is quantified from a panel of multi-system stress biomarkers to estimate cumulative stress. Our objective was to determine whether a panel of biomarkers selected for their role in allostatic load would reflect the number of documented stress events experienced by giraffes. Cortisol, DHEA-S, cholesterol, non-esterified fatty acids (NEFA), and fructosamine were determined in serum samples from zoo-housed giraffes (n = 18). These were correlated with the overall number and frequency of ZIMS-documented stress events experienced prior to blood collection. We also compared giraffes grouped by high vs. low total stress events and event frequencies. Giraffes experiencing higher total stress events tended to have 1.65-fold greater (p < 0.10) serum cortisol, had 1.49-fold greater (p < 0.05) serum fructosamine, and had 3.9-fold greater (p < 0.05) allostatic load. Giraffes experiencing higher stress-event frequency had 2.4-fold greater (p < 0.05) serum NEFA. Correlations for individual biomarkers with individual stress event categories were inconsistent, but DHEA-S (r = −0.44), cortisol/DHEA-S (r = 0.49), fructosamine (r = 0.54), and allostatic load (r = 0.49) correlated (p < 0.10) with total stress events. These findings indicate that the allostatic load index robustly reflected total cumulative stress events for these giraffes and was more consistent than the individual biomarkers used for its calculation. We conclude that allostatic load index is a promising tool for assessing stress in captive giraffes, although revision of the biomarker panel is warranted.

Intrauterine growth-restricted (IUGR) fetuses exhibit systemic inflammation that contributes to programmed deficits in myoblast function and muscle growth. Thus, we sought to determine if targeting fetal inflammation improves muscle growth outcomes. Heat stress-induced IUGR fetal lambs were infused with eicosapentaenoic acid (IUGR+EPA; n = 9) or saline (IUGR; n = 8) for 5 days during late gestation and compared to saline-infused controls (n = 11). Circulating eicosapentaenoic acid was 42% less (p < 0.05) for IUGR fetuses but was recovered in IUGR+EPA fetuses. The infusion did not improve placental function or fetal O2 but resolved the 67% greater (p < 0.05) circulating TNFα observed in IUGR fetuses. This improved myoblast function and muscle growth, as the 23% reduction (p < 0.05) in the ex vivo differentiation of IUGR myoblasts was resolved in IUGR+EPA myoblasts. Semitendinosus, longissimus dorsi, and flexor digitorum superficialis muscles were 24–39% lighter (p < 0.05) for IUGR but not for IUGR+EPA fetuses. Elevated (p < 0.05) IL6R and reduced (p < 0.05) β2 adrenoceptor content in IUGR muscle indicated enhanced inflammatory sensitivity and diminished β2 adrenergic sensitivity. Although IL6R remained elevated, β2 adrenoceptor deficits were resolved in IUGR+EPA muscle, demonstrating a unique underlying mechanism for muscle dysregulation. These findings show that fetal inflammation contributes to IUGR muscle growth deficits and thus may be an effective target for intervention.

Stress-induced fetal programming diminishes β2 adrenergic tone, which coincides with intrauterine growth restriction (IUGR) and lifelong metabolic dysfunction. We determined if stimulating β2 adrenergic activity in IUGR-born lambs would improve metabolic outcomes. IUGR lambs that received daily injections of saline or the β2 agonist clenbuterol from birth to 60 days were compared with controls from pair-fed thermoneutral pregnancies. As juveniles, IUGR lambs exhibited systemic inflammation and robust metabolic dysfunction, including greater (p < 0.05) circulating TNFα, IL-6, and non-esterified fatty acids, increased (p < 0.05) intramuscular glycogen, reduced (p < 0.05) circulating IGF-1, hindlimb blood flow, glucose-stimulated insulin secretion, and muscle glucose oxidation. Daily clenbuterol fully recovered (p < 0.05) circulating TNFα, IL-6, and non-esterified fatty acids, hindlimb blood flow, muscle glucose oxidation, and intramuscular glycogen. Glucose-stimulated insulin secretion was partially recovered (p < 0.05) in clenbuterol-treated IUGR lambs, but circulating IGF-1 was not improved. Circulating triglycerides and HDL cholesterol were elevated (p < 0.05) in clenbuterol-treated IUGR lambs, despite being normal in untreated IUGR lambs. We conclude that deficient β2 adrenergic regulation is a primary mechanism for several components of metabolic dysfunction in IUGR-born offspring and thus represents a potential therapeutic target for improving metabolic outcomes. Moreover, benefits from the β2 agonist were likely complemented by its suppression of IUGR-associated inflammation.

Background: Intrauterine growth restriction (IUGR) is associated with reduced β2 adrenergic sensitivity, which contributes to poor postnatal muscle growth. The objective of this study was to determine if stimulating β2 adrenergic activity postnatal would rescue deficits in muscle growth, body composition, and indicators of metabolic homeostasis in IUGR offspring.Methods: Time-mated ewes were housed at 40°C from day 40 to 95 of gestation to produce IUGR lambs. From birth, IUGR lambs received daily IM injections of 0.8 μg/kg clenbuterol HCl (IUGR+CLEN; n = 11) or saline placebo (IUGR; n = 12). Placebo-injected controls (n = 13) were born to pair-fed thermoneutral ewes. Biometrics were assessed weekly and body composition was estimated by ultrasound and bioelectrical impedance analysis (BIA). Lambs were necropsied at 60 days of age.Results: Bodyweights were lighter (p ≤ 0.05) for IUGR and IUGR+CLEN lambs than for controls at birth, day 30, and day 60. Average daily gain was less (p ≤ 0.05) for IUGR lambs than controls and was intermediate for IUGR+CLEN lambs. At day 58, BIA-estimated whole-body fat-free mass and ultrasound-estimated loin eye area were less (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. At necropsy, loin eye area and flexor digitorum superficialis muscles were smaller (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. Longissimus dorsi protein content was less (p ≤ 0.05) and fat-to-protein ratio was greater (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. Semitendinosus from IUGR lambs had less (p ≤ 0.05) β2 adrenoreceptor content, fewer (p ≤ 0.05) proliferating myoblasts, tended to have fewer (p = 0.08) differentiated myoblasts, and had smaller (p ≤ 0.05) muscle fibers than controls. Proliferating myoblasts and fiber size were recovered (p ≤ 0.05) in IUGR+CLEN lambs compared to IUGR lambs, but β2 adrenoreceptor content and differentiated myoblasts were not recovered. Semitendinosus lipid droplets were smaller (p ≤ 0.05) in size for IUGR lambs than for controls and were further reduced (p ≤ 0.05) in size for IUGR+CLEN lambs.Conclusion: These findings show that clenbuterol improved IUGR deficits in muscle growth and some metabolic parameters even without recovering the deficit in β2 adrenoreceptor content. We conclude that IUGR muscle remained responsive to β2 adrenergic stimulation postnatal, which may be a strategic target for improving muscle growth and body composition in IUGR-born offspring.