Della Badia Antonella, Frutos Pilar, Toral Pablo G, Hervás Gonzalo
Instituto de Ganadería de Montaña (CSIC-University of León), Finca Marzanas s/n, 24346 Grulleros, León, Spain.
Instituto de Ganadería de Montaña (CSIC-University of León), Finca Marzanas s/n, 24346 Grulleros, León, Spain.
J Dairy Sci. 2023 Jan;106(1):245-256. doi: 10.3168/jds.2022-22248. Epub 2022 Nov 16.
Small ruminants are susceptible to milk fat depression (MFD) induced by marine lipid supplementation. However, as observed in dairy cows, there is wide individual variation in the response to MFD-inducing diets, which may be due to individual differences in ruminal processes. Therefore, we compared the ruminal responses of goats and sheep with varying degrees of MFD extent to improve our understanding of this complex syndrome. Our specific aims were to attempt to elucidate whether pre-existing variations in ruminal fermentation and biohydrogenation determine a higher tolerance or susceptibility to MFD, and whether the severity of MFD depends exclusively on the response to the diet. The trial was conducted with 25 does and 23 ewes fed a basal diet without lipid supplementation for 3 wk (control period). Then, 2% fish oil (FO) was added to the same diet for 5 additional weeks (MFD period). Based on the extent of the elicited MFD (i.e., the percentage variation between milk fat concentrations recorded at the end of the control and MFD periods), the 5 most responsive (RESPON+) and the 5 least responsive (RESPON-) animals were selected within each species. On the last day of each period, ruminal fluid samples were collected to examine fermentation parameters and fatty acid profiles. In general, the individual degree of MFD in sheep and goats did not seem to be predetermined by traits related to ruminal fermentation and biohydrogenation, including fatty acids that may serve as biomarkers of microorganisms. Regarding differences in the response to FO, the results suggest no link between MFD susceptibility and concentration of biohydrogenation intermediates such as trans-10-containing C18, C20, and C22 metabolites. The explanation for individual responses based on a shortage of ruminal acetate and 18:0 for mammary uptake also seems to be dismissed, based on the lack of variation in these compounds between RESPON+ and RESPON-. However, the concentration of unsaturated fatty acids provided by FO (e.g., cis-9 16:1, cis-11 18:1, and 20:5n-3) was higher in the rumen of RESPON+ than RESPON- ewes and does. Thus, although further research is needed, the extent of biohydrogenation of these fatty acids might be associated with tolerance or susceptibility to MFD.
小型反刍动物易受补充海洋脂质诱导的乳脂降低（MFD）影响。然而，正如在奶牛中观察到的那样，对诱导MFD的日粮的反应存在很大的个体差异，这可能是由于瘤胃过程中的个体差异所致。因此，我们比较了不同程度MFD的山羊和绵羊的瘤胃反应，以增进我们对这种复杂综合征的理解。我们的具体目标是试图阐明瘤胃发酵和生物氢化过程中预先存在的差异是否决定了对MFD的更高耐受性或易感性，以及MFD的严重程度是否仅取决于对日粮的反应。试验选用25只母山羊和23只母绵羊，先饲喂3周不添加脂质的基础日粮（对照期）。然后，在相同日粮中添加2%鱼油（FO），持续5周（MFD期）。根据引发的MFD程度（即对照期和MFD期末记录的乳脂浓度之间的百分比变化），在每个物种中选择5只反应最强烈的（RESPON+）和5只反应最弱的（RESPON-）动物。在每个时期的最后一天，采集瘤胃液样本以检测发酵参数和脂肪酸谱。总体而言，绵羊和山羊的个体MFD程度似乎并非由与瘤胃发酵和生物氢化相关的特征预先决定，这些特征包括可能作为微生物生物标志物的脂肪酸。关于对FO反应的差异，结果表明MFD易感性与生物氢化中间体（如含反式-10的C18、C20和C22代谢物）的浓度之间没有关联。基于瘤胃乙酸盐和18:0缺乏用于乳腺摄取的情况来解释个体反应的说法似乎也不成立，因为在RESPON+和RESPON-之间这些化合物没有差异。然而，FO提供的不饱和脂肪酸（如顺式-9 16:1、顺式-11 18:1和20:5n-3）在RESPON+母绵羊和母山羊瘤胃中的浓度高于RESPON-。因此，尽管还需要进一步研究，但这些脂肪酸的生物氢化程度可能与对MFD的耐受性或易感性有关。
