Radix Bupleuri extract (RBE) has been shown to mitigate negative effects of high ambient temperature. This experiment was conducted to investigate effects of RBE supplementation on lactation performance and rumen fermentation in Holstein cows under heat stress. Forty Holstein cows (75 ± 15 d in milk, 37.5 ± 1.8 kg of milk/d, and 1.7 ± 0.4 parity) were randomly assigned to one of four groups (n = 10). One of four treatment diets, assigned randomly to one of four groups, consisted of RBE supplementation at 0, 0.25, 0.5 or 1.0 g/kg of the basal diet (concentrate and roughage) based on dry matter (DM). Cows were housed in a tie-stall barn and were individually fed the treatment diets. The experiment lasted for 10 wk in hot summer. During the experiment, average ambient temperatures and temperature-humidity indexes (THI) were respectively 27.5 ± 1.5, 29.8 ± 1.9 and 28.1 ± 1.7 °C, and 78.2 ± 2.7, 79.8 ± 3.3 and 78.3 ± 3.4 at 0600, 1400 and 2200 h. Average respiration rates (RR) with RBE at 0.25, 0.50 and 1.0 g/kg were 65.6, 60.3 and 67.4, respectively, vs. 71.4 (breaths/min) for the control (P < 0.01). Average rectal temperatures (RT) were 39.1, 39.0 and 39.1 vs. 39.3 °C for the control (P < 0.01). Moreover, cows supplemented with RBE increased dry matter intake (DMI, 22.8, 21.6 and 22.1 vs. 20.9 kg/d) (P < 0.05) and milk production (34.2, 33.4 and 32.4 vs. 31.6 kg/d) (P < 0.01) compared with control. Percentages of milk protein and fat were similar among groups, while milk protein yield increased with increasing level of RBE (0.97, 0.95 and 0.92 vs. 0.89 kg/d for the control) (P < 0.01). Milk fat yield also increased with RBE (1.13, 1.12 and 1.09 vs. 1.02 kg/d for the control) (P < 0.05). There was no treatment effect on diet apparent digestibility or volatile fatty acid (VFA) concentration among groups. Overall, supplemental RBE at 0.25 or 0.5 g/kg could mitigate the negative effects of heat stress on production in lactating Holstein cows.
Tag: lactation
Effects of corn straw or mixed forage diet on rumen fermentation parameters of lactating cows using a wireless data logger
The objective of this study was to evaluate the effect of two different forage types on rumen fermentation parameters and profiles using a wireless data logger. Eight lactating cows were randomly assigned to one of two dietary treatments with a low forage diet with corn straw (CS) or a high forage diet with mixed forage (MF) as the forage source, respectively. Dietary physically effective neutral detergent fiber (peNDF) content was 11.3% greater in CS. Dry matter intake and milk fatty acid content decreased upon CS (P<0.05). Ruminal pH, temperature and oxidation reduction potential (ORP) were monitored for 14weeks. The CS group had significantly higher pH but lower temperature and ORP compared to MF (P<0.01). With the CS diet regime, pH at the time before morning feeding, rumination and post-ingestion were significantly higher than those in the MF group (P<0.05). However, times with the ruminal pH below 6.0 and 5.8 were significantly reduced (P<0.05), whereas ruminal pH below 5.6 tended to be lower (P=0.07). The results indicated that rumen fermentation parameters were affected by forage types and dietary peNDF content might be predominant in ruminal pH regulation. © 2016 Japanese Society of Animal Science.