This study was carried out as an observational study in order to determine the prevalence of postpartum subclinical ketosis (SCK) in dairy herds in Hokkaido, Japan. From April 2012 to March 2014, blood β-hydroxybutyrate (BHBA) concentration was measured once within 3–88 days in milk (DIM) in 1394 apparently healthy cows from 108 farms to diagnose SCK (≥1.2 mM). In cows within 14 DIM, this was classified as SCK II, and from 15 DIM, this was classified as SCK I. Herds with a combined percentage of SCK I and SCK II of less than 10% were classified as SCK-negative herds, those with percentages of 10–25%, were classified as alert herds, and those with one of 25% or more, we classified as positive herds. The prevalence of SCK in the entire DIM was 17.6%. The prevalence of SCK II (20.2%) tended to occur more frequently than SCK I (16.5%, p = 0.094). The frequency of SCK I was higher at the fourth parity. The number of milking cows in SCK-positive herds was significantly smaller than those of the other two types of herds (p = 0.004). The frequency of SCK-positive herds in tie stalls and with component feeding was higher than for free stall or free barn and with total mixed ration (p = 0.054 and p = 0.002). This study reveals the prevalence of SCK in Hokkaido, Japan, and shows that SCK is associated with parity and the management system.

Objective: The objective of this study was to examine the effect of using a tunnel ventilation system within the dairy barn environment upon the productivity of dairy cows during the winter season. Methods: The study was performed at the University Farm, Faculty of Agriculture, Utsunomiya University. Twenty-one Holstein dairy cows (5 heifers and 16 multiparous) were enclosed in a stall barn. Unventilated (UV) and tunnel-ventilated (TV) was operated by turns every other week, and a number of key parameters were measured in the barn, including tunnel ventilation output, temperature, relative humidity, gas concentrations (oxygen [O-2], carbon dioxide [CO2], and ammonia [NH3]). Also, skin and rectal temperature, respiratory rate, blood gas concentrations, and bacterial count were measured from nipple attachments on ten cows. The amount of fodder left uneaten, and general components and somatic cell count of the milk were measured. Results: As for our dairy barn environment, air temperature dropped significantly with the passage of time with TV. Humidity was significantly higher with TV at 0600 h compared to UV, while CO2 and NH3 concentrations with UV were significantly higher than with TV at 0000 h and 0600 h. Skin temperature was significantly lower with TV compared to UV at 0000 h and 0600 h. Respiratory rate was also significantly lower at 0600 h with TV than with UV. Bacterial count for the nipple attachments was significantly lower with TV than with UV at 0600 h. The amount of leftover fodder was significantly less with TV in comparison with UV. Conclusion: Our results suggest that a TV system in the winter barn results in environmental improvements, such as reductions in unfavorable gas concentrations and bacterial growth. Consequently, it is expected that barns utilizing a TV system will be beneficial for both animal health and production.

The aim of this study was to investigate how intraduodenal infusions of fatty acids (FA) affect appetite-related gut peptides such as glucagon-like peptide-1 (GLP-1) and ghrelin in sheep. We hypothesized that these peptides can be highly reactive to unsaturated long-chain FA, because they are well known to decrease dry matter intake (DMI). Four ewes were fitted with a duodenal cannula and a jugular vein catheter for a 6-h duodenal infusion of the 9 FA (C8:0, C10:0, C12:0, C14:0, C16:0, C18:0, C18:1, C18:2, and C18:3) and water (control). The concentration of each FA was 1.6 g per metabolic body weight (BW), approximately corresponding to the amount of supplemented fat in a standard dairy cow diet. Each infusion was separated by at least 2 d. During the infusion period, blood samples were collected periodically to determine changes in plasma GLP-1, ghrelin, and metabolite concentrations. Duodenal infusions of C18:1, C18:2, and C18:3 led to higher plasma GLP-1 (P < 0.05) and lower glucose (P < 0.05) than control. Plasma ghrelin concentrations were greater in C18:1 and C18:3 infusions than control (P < 0.05). Plasma ketone bodies were higher in C8:0 and C10:0 infusions (P < 0.05), but plasma triglyceride concentrations were lower in C8:0, C10:0, C12:0, and C16:0 infusions (P < 0.05) than control. Fatty acid infusions except for C18:3 led to higher plasma NEFA concentrations than control (P < 0.05). These results confirmed that the hypophagic effect of dietary unsaturated long-chain FA is mediated by GLP-1 (an anorexigenic effect) secretion. However, we also observed higher plasma ghrelin (an orexigenic effect) partially by unsaturated long-chain FA. Thus, the gut peptide secretions when ruminant animals ingest FA supplements would complexly affect satiety and further studies are needed to determine their each impact on DMI.