Plasma Osmolality Controls Dry Forage Intake in Large-type Goats

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Heat production in ruminants follows a diurnal pattern over the course of a day peaking 3 hours following afternoon feeding and then gradually declining to its lowest point prior to morning feeding. In order to clarify the cooling period most effective in reducing decreases in feed intake and milk production, experiments were carried out based on the diurnal rhythm of heat production and heat dissipation. In experiment 1, the effects of hot environment on milk production were investigated. The animals were kept first in a thermoneutral environment (20.0°C, 80.0%) for 12 days, they were then transitioned to a hot environment (32°C, 80.0%) for 13 days before being returned to second thermoneutral environment for a further 12 days. In experiment 2, the effectiveness of daytime cooling or nighttime cooling for improving milk production in hot environment was compared. While ten lactating Japanese Saanen goats (aged 2 years, weighing 41.0 kg) during early lactation were used in experiment 1, ten lactating goats (aged 2 years, weighing 47.5 kg) during mid-lactation were used in experiment 2. The animals were fed 300 g of concentrated feed and excessive amounts of crushed alfalfa hay cubes twice daily. Water was given ad libitum. The animals were milked twice daily. When exposed to a hot environment, milk yield and composition decreased significantly (p<0.05). Milk yield in the hot environment did not change with daytime cooling, but tended to increase with nighttime cooling. Compared to the daytime cooling, milk components percentages in the nighttime cooling were not significantly different but the milk components yields in the nighttime cooling were significantly higher (p<0.05). The results indicate that nighttime cooling is more effective than daytime cooling in the reduction of milk production declines in lactating goats exposed to a hot environment.

Section: Methodsmentioning

confidence: 99%

Nighttime Cooling Is an Effective Method for Improving Milk Production in Lactating Goats Exposed to Hot and Humid Environment

Sunagawa¹,

Nagamine²,

Kamata³

et al. 2015

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“…Values are means± standard error of 8 large-type goats. a,b Means with different superscript are significantly different (p<0.05) from intraruminal infusion of hypertonic solution (RIHS) ( Thang et al, 2011b ).…”

Section: Figurementioning

confidence: 99%

“…It was difficult, therefore, to clarify which factors are mainly responsible for the control of feed intake during dry forage feeding in ruminants. In the experiments of Thang et al (2010 ; 2011 , b ; 2012a , b ), the factors that are presumed to be responsible for the control of dry forage intake were separated in esophageal-fistulated large-type goats and researched individually under sham feeding conditions (SFC). It was clarified that in large-type goats fed on dry forage for 2 h twice daily, increases in ruminal distension, plasma osmolality and subsequent thirst sensations that occurred 40 min after the start of dry forage feeding were the main physiological factors in the marked suppression of feed intake ( Thang et al, 2010 ; 2011a , b ; 2012a , b ).…”

Section: Introductionmentioning

confidence: 99%

“… Thang et al (2011b) clarified whether or not increases in plasma osmolality and subsequent thirst sensation produced by dry forage feeding suppress dry forage intake. Two experiments ( Thang et al, 2011b ) were conducted under SFC (removed boluses from esophageal cannula) using large-type male esophageal- and ruminal-fistulated goats. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 during two experiments.…”

Section: Introductionmentioning

confidence: 99%

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The Physiological Suppressing Factors of Dry Forage Intake and the Cause of Water Intake Following Dry Forage Feeding in Goats — A Review

Sunagawa

Nagamine

2015

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The goats raised in the barn are usually fed on fresh grass. As dry forage can be stored for long periods in large amounts, dry forage feeding makes it possible to feed large numbers of goats in barns. This review explains the physiological factors involved in suppressing dry forage intake and the cause of drinking following dry forage feeding. Ruminants consume an enormous amount of dry forage in a short time. Eating rates of dry forage rapidly decreased in the first 40 min of feeding and subsequently declined gradually to low states in the remaining time of the feeding period. Saliva in large-type goats is secreted in large volume during the first hour after the commencement of dry forage feeding. It was elucidated that the marked suppression of dry forage intake during the first hour was caused by a feeding-induced hypovolemia and the loss of NaHCO3 due to excessive salivation during the initial stages of dry forage feeding. On the other hand, it was indicated that the marked decrease in feed intake observed in the second hour of the 2 h feeding period was related to ruminal distension caused by the feed consumed and the copious amount of saliva secreted during dry forage feeding. In addition, results indicate that the 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. After 40 min of the 2 h dry forage feeding period, the feed salt content is absorbed into the rumen and plasma osmolality increases. The combined effects of ruminal distension and increased plasma osmolality accounted for 77.6% 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 are the main physiological factors in suppression of dry forage intake in large-type goats. There was very little drinking behavior observed during the first hour of the 2 h feeding period most water consumption occurring in the second hour. The cause of this thirst sensation during the second hour of dry forage feeding period was not hypovolemia brought about by excessive salivation, but rather increases in plasma osmolality due to the ruminal absorption of salt from the consumed feed. This suggests the water intake following dry forage feeding is determined by the level of salt content in the feed.

“… Thang et al (2010 ; 2011b) has found that in large-type esophageal-fistulated goats were fed dry forage twice daily, the marked decrease in feed intake observed in the second hour of the 2 h feeding period is related to ruminal distension caused by the feed consumed and the copious amount of saliva secreted during dry forage feeding. In addition, Thang et al (2011a) also indicated that the marked decreases in dry forage intake after 40 min of feeding are partly caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding. From these reports, it is thought that the marked decreases in dry forage intake after 40 min of feeding may be caused additively through these multiple factors produced by dry forage feeding.…”

Section: Introductionmentioning

confidence: 96%

The Main Suppressing Factors of Dry Forage Intake in Large-type Goats

Thang¹,

Sunagawa²,

Nagamine³

et al. 2012

Self Cite

: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.