Palladino Rafael Alejandro, Olmeda María Florencia, Juliano Nicolás, Bargo Fernando, Ipharraguerre Ignacio R
CONICET, Ruta 4 y Juan XXIII, Lavallol 1832, Argentina.
Facultad de Ciencias Agrarias, Universidad Nacional de Lomas de Zamora, Ruta 4 y Juan XXIII, Lavallol 1832, Argentina.
JDS Commun. 2022 Feb 10;3(2):106-109. doi: 10.3168/jdsc.2021-0158. eCollection 2022 Mar.
Evidence supports a causal link between anomalous intestinal function and impaired performance in dairy cows. Consequently, digesta pH values obtained from colon, cecum, and rectum are increasingly used to monitor intestinal function in dairy cows. We conducted a study to describe the daily dynamics of fecal pH in lactating dairy cows. The study lasted 4 d and individual records of dry matter intake, milk yield, and fecal pH were taken. Samples of feces were taken every 4 h during the 4-d study, and sampling time was adjusted ahead by 1 h daily so that a sample was obtained for each 1-h interval of the day. Data were analyzed using a mixed-effect model including time as fixed effect and cow as a random factor. We performed a cosinor analysis using pH data at different time points to determine whether fecal pH followed a biorhythmic pattern. On average, cows consumed 19.1 ± 1.55 kg/d of dry matter and produced 26.3 ± 4.16 kg/d of milk. The most relevant results confirmed a biorhythmic pattern for feces pH around feeding time: mesor (midline estimating statistic of rhythm) 6.20, amplitude 0.28, and acrophase 5.66. Additionally, we found a positive relationship between dry matter intake and amplitude, possibly because of an increase in the amount of fermentable carbohydrate reaching the hindgut in response to increasing intake. When using fecal pH as an indicator of intestinal function, it is critical to obtain samples at several time points to capture its daily rhythmicity and to report sampling time relative to feeding.
有证据支持奶牛肠道功能异常与生产性能受损之间存在因果关系。因此，从结肠、盲肠和直肠获取的食糜pH值越来越多地用于监测奶牛的肠道功能。我们开展了一项研究来描述泌乳奶牛粪便pH值的每日动态变化。该研究持续了4天，记录了干物质摄入量、产奶量和粪便pH值的个体数据。在为期4天的研究中，每4小时采集一次粪便样本，且每天将采样时间提前1小时，以便在一天中的每个1小时间隔都能获得一个样本。使用包含时间作为固定效应和奶牛作为随机因素的混合效应模型对数据进行分析。我们使用不同时间点的pH数据进行余弦分析，以确定粪便pH值是否遵循生物节律模式。奶牛平均每天消耗19.1±1.55千克干物质，产奶26.3±4.16千克。最相关的结果证实了喂食时间前后粪便pH值的生物节律模式：中值（节律的中线估计统计量）为6.20，振幅为0.28，峰值相位为5.66。此外，我们发现干物质摄入量与振幅之间存在正相关关系，这可能是由于随着摄入量增加，到达后肠的可发酵碳水化合物量增加所致。当使用粪便pH值作为肠道功能指标时，在多个时间点采集样本以捕捉其每日节律性并报告相对于喂食的采样时间至关重要。
