Department of Animal Science, Iowa State University, Ames, Iowa 50011, USA.
J Anim Sci. 2024 Jan 3;102. doi: 10.1093/jas/skae120.
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.
研究目的是描述精氨酸（CIT）在热应激（HS）和饲料限制期间对生理和肠道形态指标的影响。40 头杂交母猪（30±2kg 体重）被分配到以下五种处理之一：（1）热中性（TN）自由采食（AL）并用对照（CON）补充剂（TNAL；n=8），（2）TN 限饲（PF）并用 CON（PF-CON；n=8），（3）TN PF 用 CIT（PF-CIT；n=8），（4）HS AL 用 CON（HS-CON；n=8），和（5）HS AL 用 CIT（HS-CIT；n=8）。在 P1（7 天）期间，猪处于 TN 条件（23.6°C）并接受各自的补充处理的 AL 自由采食。在 P2（2.5 天）期间，HS-CON 和 HS-CIT 猪接受 AL 自由采食并暴露于周期性 HS（33.6 至 38.3°C），而 TNAL、PF-CON 和 PF-CIT 则保持在 TN 并接受 AL 或 PF 自由采食。CIT（0.13g/kg BW）在 P1 和 P2 期间每天口服两次。与 TN 猪相比，HS 增加了直肠温度（Tr）、皮肤温度（Ts）和呼吸率（RR）（分别为 0.8°C、4.7°C 和 47 次/分钟；P<0.01）。然而，与 HS-CON 猪相比，HS-CIT 猪的 RR（7 次/分钟，P=0.04）和 Tr 有下降的趋势（0.1°C，P=0.07）。在 P2 期间，HS 猪的采食量减少（22%；P<0.01），平均日增重有下降的趋势（P=0.08），与 TNAL 猪相比，PF 猪也遵循了相同的模式。与 TNAL 猪相比，循环脂多糖结合蛋白趋于减少（29%；P=0.08），与 PF 猪相比，HS 猪的循环脂多糖结合蛋白增加（41%；P=0.03）。与 TNAL 猪相比，PF 猪的空肠绒毛高度降低（15%；P=0.03）；然而，CIT 补充剂在饲料限制期间改善了这一指标（16%；P=0.10）。PF 猪的空肠粘膜表面积减少（16%；P=0.02），而 HS 猪的粘膜表面积有减少的趋势（11%；P=0.10），与 TNAL 猪相比。与 TNAL 猪相比，HS 猪的回肠绒毛高度和粘膜表面积减少（分别为 10%和 14%；P≤0.04），但 CIT 补充剂均可挽救这些参数（P≤0.08）。在所有处理和肠段中，肠道髓过氧化物酶和杯状细胞面积均保持相似（P>0.24）。总之，CIT 补充剂在 HS 期间略微改善了 RR 和 Tr。饲料限制和 HS 对空肠和回肠形态有不同的影响，而 CIT 虽然改善了其中一些影响，但这种益处似乎取决于肠段和应激类型。
