No abstract

When ruminants consume dry forage, they also drink large volumes of water. The objective of this study was to clarify which factor produced when feed boluses enter the rumen is mainly responsible for the marked increase in water intake in the second hour of the 2 h feeding period in large-type goats fed on dry forage for 2 h twice daily. Six large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 2 to 6 years, weighing 85.1±4.89 kg) were used in two experiments. In experiment 1, the water deprivation (WD) control and the water availability (WA) treatment were conducted to compare changes in water intake during and after dry forage feeding. In experiment 2, a normal feeding conditions (NFC) control and a feed bolus removal (FBR) treatment were carried out to investigate whether decrease in circulating plasma volume or increase in plasma osmolality is mainly responsible for the marked increase in water intake in the second hour of the 2 h feeding period. The results of experiment 1 showed that in the WA treatment, small amounts of water were consumed during the first hour of feeding while the majority of water intake was observed during the second hour of the 2 h feeding period. Therefore, the amounts of water consumed in the second hour of the 2 h feeding period accounted for 82.8% of the total water intake. The results of experiment 2 indicated that in comparison with the NFC control, decrease in plasma volume in the FBR treatment, which was indicated by increase in hematocrit and plasma total protein concentrations, was higher (p<0.05) in the second hour of the 2 h feeding period. However, plasma osmolality in the FBR treatment was lower (p<0.05) than compared to the NFC control from 30 min after the start of feeding. Therefore, thirst level in the FBR treatment was 82.7% less (p<0.01) compared with that in the NFC control upon conclusion of the 30 min drinking period. The results of the study indicate that the increased plasma osmolality in the second hour of the 2 h feeding period is the main physiological stimulating factor of water intake during and after dry forage feeding in large-type goats.

In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to clarify whether or not increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding suppress dry forage intake. Eight large-type male esophageal-and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 3 to 6 years, weighing 72.3±2.74 kg) were used in two experiments conducted under sham feeding conditions. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 h during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, an intraruminal infusion of artificial parotid saliva (RIAPS) in the control replenished saliva lost via the esophageal fistula and an intraruminal infusion of hypertonic solution (RIHS) in the treatment was carried out in order to reproduce the effects of changing salt content due to feed entering the rumen. In experiment 2, the RIHS control was conducted in the same manner as the RIHS treatment of experiment 1. The treatment group consisted of RIHS-with an intravenous infusion of artificial mixed saliva (VIAMS) treatment that was carried out for 3 h to prevent increases in plasma osmolality during feeding. The results of the RIHS treatment in experiment 1 showed that ruminal fluid osmolality increased and then an increase in plasma osmolality was observed. This resulted in the production of thirst sensations and the reduction of cumulative dry forage intake to 43.3% (p<0.05) of the RIAPS control. The results of the RIHS-VIAMS treatment in experiment 2 indicated that ruminal fluid osmolality was the same as the RIHS control but plasma osmolality significantly decreased, and thirst level was markedly reduced. This caused a significant increase of 31.4% (p<0.05) in cumulative dry forage intake in the RIHS-VIAMS treatment compared to the RIHS control. These results indicate that increases in ruminal fluid osmolality during dry forage feeding indirectly suppresses dry forage intake by causing an increase in plasma osmolality and subsequently inducing thirst sensations. The results of the present study suggest that marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding.

:In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to determine whether or not marked decreases in dry forage intake after 40 min of feeding are mainly caused by the two factors, that is, ruminal distension and increased plasma osmolality induced thirst produced by dry forage feeding. Six large-type male esophageal-and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 2 to 6 years, weighing 85.14.89 kg) were used in two experiments. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 am during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, saliva lost via the esophageal fistula was replenished by an intraruminal infusion of artificial parotid saliva (RIAPS) in sham feeding conditions (SFC) control, and the treatment was maintained under normal feeding conditions (NFC). In experiment 2, a RIAPS and non-insertion of a balloon (RIAPS-NB) control was conducted in the same manner as the SFC control of experiment 1. The intraruminal infusion of hypertonic solution and insertion of a balloon (RIHS-IB) treatment was carried out simultaneously to reproduce the effects of changing salt content and ruminal distension due to feed entering the rumen. The results of experiment 1 showed that due to the effects of multiple dry forage suppressing factors when feed boluses entered the rumen, eating rates in the NFC treatment decreased (p<0.05) after 40 min of feeding and cumulative dry forage intake for the 2 h feeding period reduced to 43.8% of the SFC control (p<0.01). The results of experiment 2 indicated that due to the two suppressing factors of ruminal distension and increased plasma osmolality induced thirst, eating rates in the RIHS-IB treatment were, as observed under NFC, reduced (p<0.05) and cumulative dry forage intake for the 2 h feeding period decreased to 34.0% of the RIAPS-NB control (p<0.01). The combined effects of ruminal distension and increased plasma osmolality accounted for 77.5% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality induced thirst are the main factors in the suppression of dry forage intake in large-type goats.

The experiment was conducted by using 20 bulls of Lai Sind cattle (a cross breed between Red Sindhi and local Vietnam yellow cattle) from 15 -16 months of age, weighed approximately 154 -156 kg, housed individually with provision of adequate feed trough and free access to water to evaluate the effect of tannin sourced from green tea by-product and addition of bio-char on methane production and animal performance. The experimental diets were formulated by replacing elephant grass in basal diet by bio-char and green tea by-product with the replacement of 0.5 -1 bio-char and 3% -5% green tea by-products, respectively to make the content of tannin in the diet of 7.3 g and 12.5 g tannin per kg dry matter. Results from this study revealed that bio-char and green tea by-product included into the diet with different levels had significantly affected on the feed intake, as the increasing level of tannin in the diet tended to increase the feed intake. The inclusion of green tea by-product in the diet which resulted in the content of tannin in the diet of 12.5 g/kg DM had significantly reduced methane emission without altering animal performance, thus the inclusion of 0.5% bio-char and 5% of green tea by-product can be applied in order to mitigate methane emission, thus contributed to environment protection.