Do volatile fatty acids control short-term feed intake in goats?
Many experiments suggest that ruminants can regulate energy intake, presumably by a negative feedback system. A case has been made for volatile fatty acids (VFA) as feedback signals. However, in most studies VFA were administered during meals whereas absorption of VFA produced in response to a meal takes place over a period of hours. Therefore, this study examines the effect of voluntary feed intake and rumen fluid VFA of continuous infusions of VFA into yhe rumen during a 5 hour periods. Four adult female goats, fed ad libitum a pelleted feed (0.5 barley : 0.5 dried grass), provided with rumen cannulae, were used to infuse VFA, neutralized with NaOH to pH 4.5-5.5, at a rate of 3.3 ml/min. Acetate, propionate and n-butyrate, separately or as a mixture, were infused at a low and a high rate; NaCl solutions served as controls. Feeding behavior was recorded continuously. Neither propionate (14 and 28 umol/kg/min) non n-butyrate (7 and 14 umol/kg/min) affected 5 h feed intake in spite of large increases of these acids in the rumen fluid. In contrast, acetate depressed 5 h feed intake by 52 percent at the high rate (91 umol/kg/min) and by 22 percent at the low rate (45 umol/kg/min). However, in both cases ruminal acetate rose to very high levels. The mixture of VFA at the low rate did not affect 5 h feed intake whereas the high rate depressed feed intake by 37 percent but the latter infusion resulted in high rumen fluid VFA levels. It is concluded that propionate and n-butyrate do not control feeding behavior whereas a role of acetate as regulator of feed intake, as suggested in the literature, is doubtful in ad libitum fed goats
| Main Authors: | , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Published: |
Scottsdale, AZ (EUA)
1982
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| Summary: | Many experiments suggest that ruminants can regulate energy intake, presumably by a negative feedback system. A case has been made for volatile fatty acids (VFA) as feedback signals. However, in most studies VFA were administered during meals whereas absorption of VFA produced in response to a meal takes place over a period of hours. Therefore, this study examines the effect of voluntary feed intake and rumen fluid VFA of continuous infusions of VFA into yhe rumen during a 5 hour periods. Four adult female goats, fed ad libitum a pelleted feed (0.5 barley : 0.5 dried grass), provided with rumen cannulae, were used to infuse VFA, neutralized with NaOH to pH 4.5-5.5, at a rate of 3.3 ml/min. Acetate, propionate and n-butyrate, separately or as a mixture, were infused at a low and a high rate; NaCl solutions served as controls. Feeding behavior was recorded continuously. Neither propionate (14 and 28 umol/kg/min) non n-butyrate (7 and 14 umol/kg/min) affected 5 h feed intake in spite of large increases of these acids in the rumen fluid. In contrast, acetate depressed 5 h feed intake by 52 percent at the high rate (91 umol/kg/min) and by 22 percent at the low rate (45 umol/kg/min). However, in both cases ruminal acetate rose to very high levels. The mixture of VFA at the low rate did not affect 5 h feed intake whereas the high rate depressed feed intake by 37 percent but the latter infusion resulted in high rumen fluid VFA levels. It is concluded that propionate and n-butyrate do not control feeding behavior whereas a role of acetate as regulator of feed intake, as suggested in the literature, is doubtful in ad libitum fed goats |
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