Detoxified castor in the diets of dairy goats: II. Lactation curves, composition, and fatty acid profile of milk

ABSTRACT We aimed to evaluate the lactation curves, composition, and fatty acid profile of milk of lactating goats fed diets containing detoxified castor cake (DCC) by alkaline solutions during 150 days of lactation. Twenty-four Saanen and Anglo Nubian goats, approximately 17 months old (first lactation) and 43±2.97 kg body weight, were distributed in a completely randomized block design with eight replicates. Treatments consisted of three diets, one containing soybean meal (SM) and two others containing DCC, with calcium hydroxide [Ca(OH)2] and sodium hydroxide (NaOH). The lactation curves showed greater persistence of lactation in Saanen goats. There were significant effects of diets on the profile of some fatty acids present in the milk. We observed that the NaOH DCC diet led to an increase in desirable fatty acid content. Both Ca(OH)2 and NaOH DCC diets led to decreased milk production during the lactation period; however, the NaOH DCC diet led to high productive efficiency. Furthermore, NaOH DCC did not negatively affect the desirable fatty acid content, unlike Ca(OH)2 DCC. Diets formulated with detoxified castor decrease the production of milk from goats during lactation phase. It should be emphasized that milk produced by goats fed DCC diets does not contain unwanted waste.**摘要** 本研究旨在评估泌乳期150天内，饲喂含经碱性溶液脱毒蓖麻饼（detoxified castor cake, DCC）日粮的泌乳山羊的泌乳曲线、乳成分及乳脂肪酸谱。试验选取24头约17月龄、初产的萨能山羊（Saanen）和英努山羊（Anglo Nubian），初始体重为43±2.97 kg，采用完全随机区组设计，设置8个重复。试验日粮共3种：1种以豆粕（soybean meal, SM）为蛋白源，另外2种以脱毒蓖麻饼为蛋白源，分别添加氢氧化钙[Ca(OH)₂]与氢氧化钠(NaOH)进行脱毒处理。泌乳曲线结果显示，萨能山羊的泌乳持久性更强。日粮对部分乳脂肪酸谱存在显著影响。研究发现，氢氧化钠脱毒蓖麻饼日粮可提升有益脂肪酸含量。饲喂氢氧化钙或氢氧化钠脱毒蓖麻饼日粮均会降低泌乳期产奶量，但氢氧化钠脱毒蓖麻饼日粮可获得较高的生产效率。此外，与氢氧化钙脱毒蓖麻饼日粮不同，氢氧化钠脱毒蓖麻饼日粮不会对有益脂肪酸含量产生负面影响。采用脱毒蓖麻饼配制的日粮会降低泌乳山羊的产奶量。需要强调的是，饲喂脱毒蓖麻饼日粮的山羊所产牛乳不含有害副产物。