Effects of grazing adaptation on intake, ruminal fermentation, blood metabolites, and body weight change in dairy cows after turning out to pasture in early spring

Abstract

Feeding management incorporating stocking for dairy cows has been widely used in temperate regions all over the world. In recent years, grazing management for dairy cows has been reevaluated due to many aspects such as animal welfare, low costs of feed, labor, manure handling, and low environmental loads. However, in temperate regions, sufficient stocking throughout the year is impossible because of the low growth of temperate grass in the winter season. Moreover, in snowy areas, cows cannot be stocked during winter and are necessary in a barn and fed conserved feeds. In using a grazing system in such situations, grazing cows are exposed to dramatic changes in feeding management between indoor feeding and stocking in early spring and autumn. When cows suddenly changed to stocking from indoor feeding, a temporary decrease in dry matter (DM) intake, body weight (BW), and milk production were observed (Charmley et al., 2003; Khanal et al., 2008). These decreases were more remarkable and it took more time for the recovery of milk compositions compared to the feeding change in autumn (Hartwiger, et al., 2018; Schären, et al., 2016). When cows turned out to stocking without adaptation, excessively decreased milk yields (Schären, et al., 2016), drastically changed milk compositions (Khanal et al., 2008; Mitani et al., 2011), and temporary decreased body weight for steers (Charmley et al., 2003) were reported in spring. These results indicated that a temporary energy deficit could occur in the early period after starting stocking. To reduce production depression, adaptation to grazing in early spring has been empirically recommended for cows to transfer

Effects of grazing adaptation on herbage intake, milk production, and body weight change in lactating dairy cows after turning out to pasture in early spring

“…Grazing adaptation affected changes in ruminal fermentation and blood metabolites during the first week after turning out to 1‐day grazing. However, the effects of grazing adaptation on rumen fermentation and PUN concentration observed in the present study were contrary to those observed in our previous study on non‐lactating cows (Mitani et al, 2020). The high total VFA concentration of the CON cows on day 2 of the experimental period was not necessarily promoted by ruminal fermentation, but it may be affected by the concentration effect of ruminal pool size, which was smaller due to the lower herbage intake of these cows than of the ADP cows.…”

“…The results of the present study clearly indicated that the total DMI significantly decreased after turning out from indoor feeding to 1‐day grazing when the cows were not adapted to grazing. The results of continuous measurement of herbage DMI in lactating cows in the present study are similar to those reported in our previous study on non‐lactating cows (Mitani et al, 2020). The change and difference in herbage DMI during the first week of the transition period from indoor feeding to 1‐day grazing affected the performance of cows during the 4‐week period of 1‐day grazing.…”

“…To assess grazing adaptability, gradual changes in herbage DMI, particularly in the first week of the transition period from indoor feeding to grazing, should be measured. However, no study has investigated such changes in herbage DMI during this period, except our present and previous studies (Mitani et al, 2020). Other previous studies investigated the effects of grazing adaptation using only oneor two-point measurements of herbage DMI at 3 or 4 weeks after turning out from indoor feeding to 1-day grazing (Hartwiger, Schären, Potthoff, et al, 2018;Schären, Seyfang, et al, 2016).…”

“…The feces in the rectum were collected at 08:00 and 15:00 h every day and pooled for days 1–3 and 4–7 of the adaptation period and days 1–3, 4–7, 8–14, 15–21, and 22–28 days of the experimental period. The concentration of La and C33 alkanes in the herbage, supplied feed, and fecal samples was determined as described previously (Mitani et al, 2020). Herbage DM intake was estimated using a previously described method (Mitani et al, 2020).…”

“…The concentration of La and C33 alkanes in the herbage, supplied feed, and fecal samples was determined as described previously (Mitani et al, 2020). Herbage DM intake was estimated using a previously described method (Mitani et al, 2020). Total tract apparent OM digestibility was calculated based on the total OM intake and fecal OM.…”