Johnson J S, Sanz Fernandez M V, Gutierrez N A, Patience J F, Ross J W, Gabler N K, Lucy M C, Safranski T J, Rhoads R P, Baumgard L H
Department of Animal Science, Iowa State University, Ames 50011.
Division of Animal Sciences, University of Missouri, Columbia 65211.
J Anim Sci. 2015 Jan;93(1):71-81. doi: 10.2527/jas.2014-8354.
Environmentally induced heat stress (HS) negatively influences production variables in agriculturally important species. However, the extent to which HS experienced in utero affects nutrient partitioning during the rapid lean tissue accretion phase of postnatal growth is unknown. Study objectives were to compare future whole-body tissue accretion rates in pigs exposed to differing in utero and postnatal thermal environments when lean tissue deposition is likely maximized. Pregnant sows were exposed to thermoneutral (TN; cyclical 15°C nighttime and 22°C daytime; n = 9) or HS (cyclical 27°C nighttime and 37°C daytime; n = 12) conditions during their entire gestation. Twenty-four offspring from in utero TN (IUTN; n = 6 gilts and 6 barrows; 30.8 ± 0.2 kg BW) and in utero HS (IUHS; n = 6 gilts and 6 barrows; 30.3 ± 0.2 kg BW) were euthanized as an initial slaughter group (ISG). Following the ISG, 48 pigs from IUTN (n = 12 gilts and 12 barrows; 34.1 ± 0.5 kg BW) and IUHS (n = 12 gilts and 12 barrows; 33.3 ± 0.3 kg BW) were exposed to constant HS (34.1 ± 2.4°C) or TN (21.5 ± 2.0°C) conditions until they reached 61.5 ± 0.8 kg BW, at which point they were sacrificed and their whole-body composition was determined. Homogenized carcasses were analyzed for N, crude fat, ash, water, and GE content. Data were analyzed using PROC MIXED in SAS 9.3. Rectal temperature and respiration rate increased (P < 0.01) during postnatal HS compared to TN (39.4 vs. 39.0°C and 94 vs. 49 breaths per minute, respectively). Regardless of in utero environment, postnatal HS reduced (P < 0.01) feed intake (2.06 vs. 2.37 kg/d) and ADG (0.86 vs. 0.98 kg/d) compared to TN conditions. Postnatal HS did not alter water, protein, and ash accretion rates but reduced lipid accretion rates (198 vs. 232 g/d; P < 0.04) compared to TN-reared pigs. In utero environment had no effect on future tissue deposition rates; however, IUHS pigs from the ISG had reduced liver weight (P < 0.04; 17.9%) compared to IUTN controls. In summary, postnatal HS reduced adipose tissue accretion rates, but IUHS did not appear to impact either lean or adipose tissue accretion during this specific growth phase.
环境诱导的热应激（HS）对农业重要物种的生产变量产生负面影响。然而，子宫内经历的热应激在出生后生长的快速瘦肉组织增生阶段对营养分配的影响程度尚不清楚。研究目的是比较在瘦肉组织沉积可能最大化时，暴露于不同子宫内和出生后热环境的猪未来的全身组织增生率。妊娠母猪在整个妊娠期暴露于热中性（TN；夜间15°C和白天22°C循环；n = 9）或热应激（HS；夜间27°C和白天37°C循环；n = 12）条件下。来自子宫内热中性（IUTN；n = 6头小母猪和6头公猪；体重30.8±0.2 kg）和子宫内热应激（IUHS；n = 6头小母猪和6头公猪；体重30.3±0.2 kg）的24只后代作为初始屠宰组（ISG）被安乐死。在ISG之后，来自IUTN（n = 12头小母猪和12头公猪；体重34.1±0.5 kg）和IUHS（n = 12头小母猪和12头公猪；体重33.3±0.3 kg）的48头猪暴露于恒定热应激（34.1±2.4°C）或热中性（21.5±2.0°C）条件下，直到它们达到体重61.5±0.8 kg，此时将它们处死并测定其全身组成。对匀浆后的胴体进行氮、粗脂肪、灰分、水分和总能含量分析。数据使用SAS 9.3中的PROC MIXED进行分析。与热中性相比，出生后热应激期间直肠温度和呼吸频率升高（P < 0.01）（分别为39.4 vs. 39.0°C和94 vs. 49次呼吸/分钟）。无论子宫内环境如何，与热中性条件相比，出生后热应激降低（P < 0.01）采食量（2.06 vs. 2.37 kg/d）和平均日增重（0.86 vs. 0.98 kg/d）。出生后热应激没有改变水分、蛋白质和灰分的增生率，但与热中性饲养的猪相比，降低了脂质增生率（198 vs. 232 g/d；P < 0.04）。子宫内环境对未来组织沉积率没有影响；然而，与IUTN对照组相比，ISG中的IUHS猪肝脏重量降低（P < 0.04；17.9%）。总之，出生后热应激降低了脂肪组织增生率，但在这个特定生长阶段，IUHS似乎对瘦肉或脂肪组织增生均无影响。
