The objective was to evaluate the effects of porcine reproductive and respiratory syndrome virus (PRRSV) infection and dietary soy isoflavone (ISF) supplementation on carcass cutability and meat quality of commercial pigs. Barrows (21 d of age) were randomly allotted to experimental treatments that were maintained throughout the study: noninfected pigs received an ISF-devoid control diet (CON, n = 22) and infected pigs received either the control diet (PRRSV–CON, n = 20) or that supplemented with total ISF in excess of 1,500 mg/kg (PRRSV–ISF, n = 25). Pigs were penned by treatment, with six pigs within a pen. Following a 7-d adaptation, weanling pigs were inoculated once intranasally with either a sham-control (phosphate buffered saline [PBS]) or live PRRSV (1 × 10⁵ tissue culture infective dose [TCID]₅₀/mL, strain NADC20). Pigs were maintained on experimental diets for 166 d after inoculation and then slaughtered (192 or 194 d of age; approximately 120 kg body weight [BW]). At 1-d postmortem, left sides were separated between the 10th and 11th rib for the determination of loin eye area (LEA), backfat (BF) thickness, and loin quality (ultimate pH, instrumental color, drip loss, visual color, marbling, and firmness). Loin chops were aged 14 d postmortem prior to Warner–Bratzler shear force (WBSF) determination. Belly width, length, thickness, and flop distance were determined. Data were analyzed as a one-way ANOVA with pig as the experimental unit. Carcass yield, LEA, BF, and estimated lean percentage did not differ (P > 0.26) among treatments. Loins from CON pigs had increased ultimate pH (P = 0.01), reduced L* scores (P = 0.005) coupled with darker visual color scores (P = 0.004), were firmer (P < 0.0001), and exhibited reduced drip loss (P = 0.01) compared with PRRSV–CON and PRRSV–ISF pigs. However, WBSF did not differ (P = 0.51) among treatments after 14 d of aging. Bellies from CON pigs were more firm compared with bellies from PRRSV–CON and ISF pigs (P < 0.01). These data suggest PRRSV infection did not alter carcass characteristics but may have marginally reduced loin and belly quality. Supplementation with dietary soy isoflavones did nothing to mitigate the detrimental effects of PRRSV infection.

中文翻译：

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猪繁殖与呼吸综合征病毒感染和补充大豆异黄酮对猪胴体可分割性和肉品质的影响。

目的是评估猪繁殖与呼吸综合征病毒 ( PRRSV ) 感染和日粮中添加大豆异黄酮 ( ISF ) 对商品猪胴体可分割性和肉质的影响。公猪（21 日龄）被随机分配到在整个研究过程中维持的实验处理：未感染的猪接受不含 ISF 的对照饮食（CON，n = 22），感染的猪接受对照饮食（PRRSV-CON，n = 20) 或补充总 ISF 超过 1,500 mg/kg (PRRSV-ISF, n = 25)。猪经过治疗后被圈养，一个圈内有六头猪。经过 7 天的适应后，断奶仔猪鼻内接种一次假对照（磷酸盐缓冲盐水 [PBS]）或活 PRRSV（1 × 10 ⁵组织培养感染剂量 [TCID] ₅₀ /mL，菌株 NADC20）。猪在接种后保持实验饲料 166 天，然后屠宰（192 或 194 天龄；约 120 公斤体重 [BW]）。宰后第 1 天，将左侧第 10 和第 11 肋骨分离，测定腰肉眼面积 ( LEA )、背膘 ( BF ) 厚度和腰肉质量（最终 pH、仪器颜色、滴水损失、视觉颜色、大理石花纹）和硬度）。在测定Warner-Bratzler 剪切力 ( WBSF ) 之前，将腰排在死后 14 天进行老化。确定腹部宽度、长度、厚度和下垂距离。以猪为实验单位，对数据进行单向方差分析。各处理间胴体产量、LEA、BF 和估计瘦肉率没有差异 ( P > 0.26)。CON 猪的腰部最终 pH 值升高 ( P = 0.01)，L* 分数降低 ( P = 0.005)，视觉颜色分数加深 ( P = 0.004)，更坚硬 ( P < 0.0001)，并且滴水损失减少 ( P = 0.01) 与 PRRSV–CON 和 PRRSV–ISF 猪相比。然而，老化 14 天后，各处理之间的WBSF 没有差异（P = 0.51）。与 PRRSV-CON 和 ISF 猪的腹部相比，CON 猪的腹部更坚硬（P < 0.01）。这些数据表明 PRRSV 感染不会改变胴体特征，但可能会略微降低腰部和腹部质量。膳食中补充大豆异黄酮并不能减轻 PRRSV 感染的有害影响。