Effect of cassava wastewater on physicochemical characteristics and fatty acids composition of meat from feedlot-finished lambs

ABSTRACT. This study aimed to evaluate the effects of includingcassava wastewater (0.0, 0.5, 1.0, or 1.5 L animal-1 day-1) in diets of feedlot-finished lambs on the physicochemical characteristics and fatty acid composition of their meat. Thirty-two uncastrated lambs atan average age of 167 days and an average body weight of 24.76 ± 3.00 kg were distributed into four groups in a completely randomized design with eight animals per group for each treatment. Color values were measured on the longissimus dorsi muscle using a portable colorimeter. To determine the cooking losses, samples of meat were cut and weighed. Individual pieces were cooked in an electric oven to a defined internal temperature (72°C). The composition of fatty acids were measured by gas chromatography.Inclusion of cassava wastewater linearly reduced cooking losses, shear force, and yellow intensity and linearly increased the fat content of the meat. The amounts of myristic, stearic, linoleic, and total fatty acids were changed. Additionally, an effect of cassava wastewater was observed on the amounts of saturated fatty acids, polyunsaturated fatty acids, desirable fatty acids, and n-6:n-3ratio. A positive quadratic effect was observed for the following nutritional quality indices: Δ9 desaturase 16, elongase, at herogenicity, and thrombogenicity. Cassava wastewater changesthe physicochemical characteristics and fatty acid composition of lamb meat. Furtherstudies should be carried outto more accurately determine the fatty acid composition of cassava wastewater to better understand its effectson animal nutrition.

摘要
本研究旨在评估在舍饲育肥羔羊的日粮中添加木薯废水（cassava wastewater，添加量设置为0.0、0.5、1.0或1.5 L·头⁻¹·日⁻¹）对其肉品理化特性及脂肪酸组成的影响。本试验选取32只平均日龄167 d、平均体重24.76±3.00 kg的未去势羔羊，采用完全随机设计将其分为4组，每组8只，每处理对应一组。

采用便携式色差仪（portable colorimeter）对背最长肌（longissimus dorsi muscle）的色泽参数进行测定。为测定蒸煮损失（cooking losses），将肉样切块并称重，随后将肉块置于电烤箱中加热至核心温度达72℃。脂肪酸组成通过气相色谱法（gas chromatography）进行测定。

日粮中添加木薯废水可使肉品的蒸煮损失、剪切力（shear force）及黄度值呈线性降低，同时使肉品脂肪含量呈线性升高；肉豆蔻酸、硬脂酸、亚油酸及总脂肪酸的含量均发生改变。此外，木薯废水添加量对饱和脂肪酸（saturated fatty acids）、多不饱和脂肪酸（polyunsaturated fatty acids）、有益脂肪酸及n-6:n-3比值（n-6:n-3 ratio）均存在显著影响。下述营养品质指标均呈现正向二次效应：Δ9去饱和酶（Δ9 desaturase）16、延长酶（elongase）、致动脉粥样硬化指数（atherogenicity）及血栓形成指数（thrombogenicity）。

综上，木薯废水可改变羔羊肉品的理化特性与脂肪酸组成。未来需开展进一步研究，精准测定木薯废水中的脂肪酸组成，以更深入地阐明其对动物营养的影响。