Department of Physiology and Biochemistry of Animal Nutrition, Estación Experimental del Zaidín, CSIC, Camino del Jueves s/n, 18100, Armilla, Granada, Spain.
Department of Physiology and Biochemistry of Animal Nutrition, Estación Experimental del Zaidín, CSIC, Camino del Jueves s/n, 18100, Armilla, Granada, Spain.
J Therm Biol. 2022 May;106:103230. doi: 10.1016/j.jtherbio.2022.103230. Epub 2022 Mar 30.
The effects of heat stress and dietary betaine and zinc on growth, weight of organs and plasma biochemistry in growing Iberian pigs are of special importance. Forty Iberian barrows (43.8 kg BW) were assigned to five treatments for 28-d: 1.-thermoneutral (20 °C)-ad libitum fed a control diet (TN-CON); 2.-heat stress (30 °C)-ad libitum fed a control diet (HS-CON); 3.-thermoneutral-pair-fed a control diet (TN-CON-PF) on the basis of intake of HS-CON; 4.-heat stress-ad libitum fed a betaine-supplemented diet (HS-BET); 5.-heat stress-ad libitum fed a zinc-supplemented diet (HS-ZN). Heat stress increased rectal temperature and decreased feed intake. As a result, weight gain under TN-CON was greater than under heat stress or TN-CON-PF. Temperature did not affect gain to feed ratio. Heat stress decreased empty BW, kidneys and spleen weights, and tended to decrease total viscera weight compared to thermoneutral counterparts fed ad libitum, but when organ weight was related to empty BW, only spleen tended to decrease. At identical intake, heat stress tended to decrease heart weight. Betaine and zinc had no effect on organs weight under heat stress. Heat stress decreased albumin and the homeostasis model assessment index for estimating β-cell function (HOMA-%B), increased glucose, and tended to increase urea compared with the TN pair-fed group. Betaine and zinc decreased plasma glucose under heat stress and increased HOMA-%B suggesting improved β-cell function. Insulin, quantitative insulin sensitivity check index, homeostasis model assessment index for estimating insulin resistance percentage and the rest of biochemical parameters were not affected by treatments. Decreased intake explained the consistent negative effects on performance of pigs after long-term heat stress. Furthermore, it elicited a glucose sparing effect without affecting insulin concentration and increased protein catabolism. Betaine or zinc supplementation did not prevent the negative effect of heat stress on growth performance of Iberian pigs.
热应激以及饲粮甜菜碱和锌对生长、器官重量和血浆生化特性的影响对于伊比利亚猪尤为重要。选择 40 头 43.8kg 体重的伊比利亚公猪，分为 5 个处理组，每组 8 头猪，每个处理组 28d：1. 常温（20℃）自由采食对照组日粮（TN-CON）；2. 热应激（30℃）自由采食对照组日粮（HS-CON）；3. 常温限饲对照组日粮（TN-CON-PF），采食基于 HS-CON 组；4. 热应激自由采食添加甜菜碱的日粮（HS-BET）；5. 热应激自由采食添加锌的日粮（HS-ZN）。热应激增加了直肠温度，降低了采食量。结果，TN-CON 组的增重大于热应激或 TN-CON-PF 组。温度对增重/采食量比没有影响。热应激降低了空腹 BW、肾脏和脾脏重量，并且与自由采食的常温猪相比，总内脏重量有降低的趋势，但当器官重量与空腹 BW 相关时，只有脾脏有降低的趋势。在相同的采食量下，热应激有降低心脏重量的趋势。甜菜碱和锌对热应激下的器官重量没有影响。热应激降低了白蛋白和估计胰岛β细胞功能的稳态模型评估指数（HOMA-%B），增加了葡萄糖，并使尿素趋于增加，与 TN 配对饲喂组相比。与热应激相比，甜菜碱和锌降低了血浆葡萄糖，增加了 HOMA-%B，提示β细胞功能改善。胰岛素、定量胰岛素敏感性检测指数、估计胰岛素抵抗百分比的稳态模型评估指数和其余生化参数不受处理的影响。长期热应激导致采食量下降，从而对猪的生产性能产生一致的负面影响。此外，它引起了葡萄糖节约效应，而不影响胰岛素浓度并增加了蛋白质分解代谢。甜菜碱或锌的补充并不能防止热应激对伊比利亚猪生长性能的负面影响。
