PDF(Pubmed)
Abstract：
Study objectives were to characterize the effects of citrulline (CIT) on physiological and intestinal morphology metrics during heat stress (HS) and feed restriction. Forty crossbred gilts (30 ± 2 kg body weight [BW]) were assigned to one of five treatments: (1) thermoneutral (TN) fed ad libitum (AL) with control (CON) supplement (TNAL; n = 8), (2) TN pair-fed (PF) with CON (PF-CON; n = 8), (3) TN PF with CIT (PF-CIT; n = 8), (4) HS AL with CON (HS-CON; n = 8), and (5) HS AL with CIT (HS-CIT; n = 8). During the period (P) 1 (7 d), pigs were in TN conditions (23.6 °C) and fed AL their respective supplemental treatments. During P2 (2.5 d), HS-CON and HS-CIT pigs were fed AL and exposed to cyclical HS (33.6 to 38.3 °C), while TNAL, PF-CON, and PF-CIT remained in TN and were fed either AL or PF to their HS counterparts. Citrulline (0.13 g/kg BW) was orally administered twice daily during P1 and P2. HS increased rectal temperature (Tr), skin temperature (Ts), and respiration rate (RR) relative to TN pigs (0.8 °C, 4.7 °C, and 47 breaths/min, respectively; P < 0.01). However, HS-CIT had decreased RR (7 breaths/min, P = 0.04) and a tendency for decreased Tr (0.1 °C, P = 0.07) relative to HS-CON pigs. During P2, HS pigs had decreased feed intake (22%; P < 0.01) and a tendency for decreased average daily gain (P = 0.08) relative to TNAL pigs, and by experimental design, PF pigs followed this same pattern. Circulating lipopolysaccharide-binding protein tended to be decreased (29%; P = 0.08) in PF relative to TNAL pigs and was increased (41%; P = 0.03) in HS compared to PF pigs. Jejunum villus height was decreased in PF relative to TNAL pigs (15%; P = 0.03); however, CIT supplementation improved this metric during feed restriction (16%; P = 0.10). Jejunum mucosal surface area decreased in PF (16%; P = 0.02) and tended to decrease in HS (11%; P = 0.10) compared to TNAL pigs. Ileum villus height and mucosal surface area decreased in HS compared to TNAL pigs (10 and 14%, respectively; P ≤ 0.04), but both parameters were rescued by CIT supplementation (P ≤ 0.08). Intestinal myeloperoxidase and goblet cell area remained similar among treatments and intestinal segments (P > 0.24). In summary, CIT supplementation slightly improved RR and Tr during HS. Feed restriction and HS differentially affected jejunum and ileum morphology and while CIT ameliorated some of these effects, the benefit appeared dependent on intestinal section and stressor type.
Heat stress (HS) negatively affects animal health and production efficiency and is a significant economic burden to global animal agriculture. Although the mechanisms responsible for reduced animal productivity during HS are complex and multifaceted, increasing evidence points to decreased intestinal barrier function as an important mediator of this response. Furthermore, HS causes a voluntary reduction in feed intake, and feed restriction independently induces gastrointestinal hyperpermeability. Loss of intestinal barrier integrity facilitates bacteria translocation across the epithelium into local and systemic circulation, thus initiating an immune response. Dietary citrulline has been shown to support gut health by improving intestinal barrier integrity and modulating intestinal inflammation. Therefore, the current study investigated the effects of citrulline supplementation on physiological and intestinal morphology parameters in heat-stressed and feed-restricted growing pigs. Herein, citrulline supplementation reduced respiration rate and rectal temperature in pigs exposed to the thermal load. Heat stress and feed restriction compromised small intestinal morphology, and while supplementing citrulline improved some of these parameters, the effects depended on the intestinal region and stressor type. Additional research is needed to evaluate the potential effects of citrulline supplementation on gut health during HS or nutrient restriction.
Heat stress (HS) negatively affects animal health and production efficiency and is a significant economic burden to global animal agriculture. Although the mechanisms responsible for reduced animal productivity during HS are complex and multifaceted, increasing evidence points to decreased intestinal barrier function as an important mediator of this response. Furthermore, HS causes a voluntary reduction in feed intake, and feed restriction independently induces gastrointestinal hyperpermeability. Loss of intestinal barrier integrity facilitates bacteria translocation across the epithelium into local and systemic circulation, thus initiating an immune response. Dietary citrulline has been shown to support gut health by improving intestinal barrier integrity and modulating intestinal inflammation. Therefore, the current study investigated the effects of citrulline supplementation on physiological and intestinal morphology parameters in heat-stressed and feed-restricted growing pigs. Herein, citrulline supplementation reduced respiration rate and rectal temperature in pigs exposed to the thermal load. Heat stress and feed restriction compromised small intestinal morphology, and while supplementing citrulline improved some of these parameters, the effects depended on the intestinal region and stressor type. Additional research is needed to evaluate the potential effects of citrulline supplementation on gut health during HS or nutrient restriction.
摘要：
研究目的是表征在热应激(HS)和饲料限制期间瓜氨酸(CIT)对生理和肠形态指标的影响。将40只杂交母猪（30±2kg体重[BW]）分配给五种处理方法之一：（1）用对照（CON）补充剂（TNAL；n=8）随意饲喂热中性（TN），（2）具有CON（PF-CON；n=8）的TN配对（PF），(3)TNPF与CIT(PF-CIT；n=8)，(4)带CON的HSAL(HS-CON；n=8)，和（5）HSAL与CIT（HS-CIT；n=8）。在(P)1(7d)期间，猪处于TN条件下(23.6°C),并饲喂其各自的补充处理。在P2（2.5d）期间，HS-CON和HS-CIT猪饲喂AL并暴露于周期性HS（33.6至38.3°C），而TNAL,PF-CON,和PF-CIT留在TN，并将AL或PF喂给HS对应者。在P1和P2期间每天两次口服瓜氨酸(0.13g/kg体重)。HS直肠温度（Tr）升高，皮肤温度（Ts），和呼吸率（RR）相对于TN猪（0.8°C，4.7°C,和47次呼吸/分钟，分别；P<0.01）。然而,HS-CIT降低了RR(7次呼吸/分钟，P=0.04)和Tr降低的趋势(0.1°C，P=0.07）相对于HS-CON猪。在P2期间，HS猪的采食量减少（22％；P<0.01），并且相对于TNAL猪的平均日增重下降趋势（P=0.08），通过实验设计，PF猪遵循相同的模式。相对于TNAL猪，PF中的循环脂多糖结合蛋白倾向于降低（29％；P=0.08），而与PF猪相比，HS中的循环脂多糖结合蛋白倾向于降低（41％；P=0.03）。相对于TNAL猪，PF的空肠绒毛高度降低（15％；P=0.03）；然而，CIT补充在饲料限制期间改善了这一指标(16%；P=0.10)。与TNAL猪相比，PF的空肠粘膜表面积降低（16％；P=0.02），HS的空肠粘膜表面积趋于降低（11％；P=0.10）。与TNAL猪相比，HS的回肠绒毛高度和粘膜表面积降低（10％和14％，分别为；P≤0.04)，但这两个参数均通过补充CIT（P≤0.08）得到挽救。肠髓过氧化物酶和杯状细胞面积在治疗和肠段之间保持相似(P>0.24)。总之,补充CIT略微改善了HS期间的RR和Tr。限制采食和HS差异影响空肠和回肠形态，而CIT改善了其中一些影响，获益似乎取决于肠道切片和应激源类型。
热应激（HS）对动物健康和生产效率产生负面影响，是全球畜牧业的重大经济负担。虽然导致HS期间动物生产力降低的机制是复杂和多方面的，越来越多的证据表明肠屏障功能下降是这种反应的重要介质。此外，HS导致饲料摄入量的自愿减少，和饲料限制独立地诱导胃肠道通透性过高。肠屏障完整性的丧失促进细菌通过上皮易位进入局部和全身循环。从而引发免疫反应。膳食瓜氨酸已被证明通过改善肠屏障完整性和调节肠道炎症来支持肠道健康。因此,本研究调查了补充瓜氨酸对热应激和限食生长猪生理和肠道形态参数的影响。在这里，补充瓜氨酸可降低暴露于热负荷的猪的呼吸速率和直肠温度。热应激和采食限制损害了小肠形态，虽然补充瓜氨酸改善了这些参数中的一些，影响取决于肠道区域和应激源类型。需要更多的研究来评估在HS或营养限制期间补充瓜氨酸对肠道健康的潜在影响。
热应激（HS）对动物健康和生产效率产生负面影响，是全球畜牧业的重大经济负担。虽然导致HS期间动物生产力降低的机制是复杂和多方面的，越来越多的证据表明肠屏障功能下降是这种反应的重要介质。此外，HS导致饲料摄入量的自愿减少，和饲料限制独立地诱导胃肠道通透性过高。肠屏障完整性的丧失促进细菌通过上皮易位进入局部和全身循环。从而引发免疫反应。膳食瓜氨酸已被证明通过改善肠屏障完整性和调节肠道炎症来支持肠道健康。因此,本研究调查了补充瓜氨酸对热应激和限食生长猪生理和肠道形态参数的影响。在这里，补充瓜氨酸可降低暴露于热负荷的猪的呼吸速率和直肠温度。热应激和采食限制损害了小肠形态，虽然补充瓜氨酸改善了这些参数中的一些，影响取决于肠道区域和应激源类型。需要更多的研究来评估在HS或营养限制期间补充瓜氨酸对肠道健康的潜在影响。
