- Email: [email protected]
Ruminal Bypass of Drinking Water in Lactating Cows1
Ruminal
Bypass of Drinking
W a t e r in L a c t a t i n g C o w s 1 S. T. WOODFORD, = M. R. MURPHY, = C. L. DAVIS, = and K. R. HOLMES 3 University of Illinois Urbana 61801
ABSTRACT
assumptions that 1) water consumed by mature ruminants equilibrates with that in the reticulorumen, and 2) net transruminal water flux is minimal, has been used to relate water consumption to total ruminal fluid outflow (12). Rogers et al. (12) reported 80% of fluid leaving the reticulorumen of lactating cows was accounted for by water intake. Similar measurements of steers led to 43% (13). These observations suggest either alteration of salivary flow in association with higher feed intake (12) or significant ruminal bypass (water that does not equilibrate with that in the rumen) of drinking water in lactating cows. Ruminal bypass of drinking water has been described in sheep that after drinking a known amount of water had a higher than expected concentration of water-soluble marker in theii" rumen (.14). This phenomenon also has been reported by (6, 15) in which ruminal water bypass was related to ruminal fill at time of drinking.
Drinking water that does not equilibrate with ruminal fluid, i.e., bypasses the rumen, was studied qualitatively and quantitatively in eight rumen-fistulated lactating Holstein cows. Decreased temperatures in the sulcus omasi and abomasum shortly after initiation of drinking indicated that water had bypassed the rumen. Recovery of a water-soluble marker, included in drinking water offered after water was withheld for 4.5 or 9 h following feeding, was used to estimate ruminal bypass. For respective treatments, 18 and 5% of drinking water was calculated to have bypassed the rumen. Ruminal bypass in lactating cows drinking relatively large amounts of water could affect comparisons of water intake with total ruminal fluid outflow as measured by dilution of a water-soluble marker. Drinking water should not be assumed to equilibrate with ruminal fluid.
MATERIALS AND METHODS
INTRODUCTION
Passage of water through the reticulorumen is an important component of digestion. In addition to its metabolic functions, water also serves as a vehicle for digesta transport out of the rumen (5, 9). Saliva, ingested water, and fluid movement across the reticulorumen wall contribute to calculations of net water flow (]0). Dilution of water soluble markers often is used to estimate ruminal fluid volume and outflow. This technique, based on the underlying
Received February 2, !984. t Supported by lllinois Agricultural Experiment Station, Hatch 35-0360. z Department of Dairy Science. 3Deparmaent of Veterinary Biosciences. 1984 J Dairy Sci 67:2471-2474
In Trial 1 temperatures of abomasum and sulcus omasi were monitored qualitatively to examine ruminal bypass of water after drinking. A second trial was designed to provide a quantitative estimate of water bypass by measuring recovery of an orally consumed marker from the rumen. Trial 1
Eight multiparous rumen-fistulated Holstein cows, approximately 630 kg and in middle to late lactation, were fed 2.0 kg (dry matter) alfalfa hay daily, corn silage, and alfalfa haylage (50:50 dry matter) for ad libitum intake and high moisture corn and mineral supplemented soybean meal to production. Cows were fed at 1200 and 1530 h. A 2-wk adjustment preceded the trial. Animals were stanchioned except for milking at 0500 and 1500 h and allowed to exercise from 0600 to 1130 h. Water was available at all times.
2471
2472
WOODFORD ET AL.
Thermistor bead temperature probes (P25BA202N; Thermometrics Inc., Edison, N J) were used to measure temperature in the abomasum and sulcus omasi during and after consumption of cold water. The temperature probe was soldered to wire leads and connections, and probe were coated in epoxy, except for the probe tip, which was exposed. Our temperature measuring circuit was modified from Chen et al. (2). Temperature changes then were calculated from each probe's circuit output to a two channel chart recorder (2). A perforated rubber flange (10 cm diameter) was placed 20 cm from the terminal thermistor "A". A second thermistor, "B", was placed 8 cm behind the flange. On the day of measurement at 1200 h the probe assembly was inserted through the rumen fistula, and the rubber flange and probe "A" were placed in the abomasum which positioned probe "B" in the sulcus omasi. An X-ray was taken to verify probe placement in a Holstein steer. Water (2°C) was offered, on demand, from 26-liter containers via a gravity fed 2 cm diameter tube leading to the animal's drinking cup. Abomasal and sulcus omasal temperatures were recorded until they stabilized after consumption of water.
Trial 2
Cows and diets were the same as in Trial 1. Milking and feeding occurred at 0500 and 1500 h and 0530 and 1530 h, respectively. Otherwise animals were kept stanchioned to prevent access to unmetered water.
Animals were assigned randomly to treatments in which water was withheld for either 4.5 h or 9 h after 0500 h. After 7 days treatments were reversed. Water containing 3.8 g/ liter polyethylene glycol (PEG, M r 4000) was offered as in Trial 1. Samples of water were taken during delivery for PEG analysis. An animal was allowed to consume water containing PEG for 15 min at the appropriate time (0930 or 1400 h) after which the rumen was emptied immediately. Contents were weighed, mixed by hand, and duplicate samples were taken for dry matter and PEG analyses. Ruminal contents then were replaced, which completed this part of the procedure. Removal and replacement of contents of the rumen required about 45 min. Seven hourly fluid samples were taken from several points in the rumen by perforated tube/ suction flask to estimate dilution rate of ruminal fluid. Twice during the experiment when the cows were not being used for bypass measurements, hourly water intakes were measured on six cows between 0530 and 1530 h. Ruminal fluid was centrifuged at 12,000 × g for 15 min and supernatant frozen for analysis. Dry matter content of rumen was determined on samples dried at 55°C. Polyethylene glycol was measured as outlined by Rogers et al. (12). Feed samples were analyzed for crude protein, ether extract, ash (1), and acid detergent fiber (4). Percent of consumed water that bypassed the rumen was estimated by recovery of PEG in rumen contents. Three animals did not drink on both treatments; therefore, data from these animals were not used. Statistical analysis of the data was by a paired comparison between treatments (SAS Institute, Cary, NC).
TABLE 1. Composition of feedstuffs.
High Component
Alfalfa hay
Haylagesilage
moisture corn
Soybean meaP
Dry matter, %
90.0
50.9
81.5
91.5
Crude protein Acid detergent fiber Ether extract Ash
17.7 45.4 4.2 8.4
11.0 40.0 5.1 8.5
(% of dry matter)
1Includes trace mineral salt. Journal of Dairy Science Vol. 67, No. 10, 1984
9.4 4.2 4.3 1.5
45.6 8.0 1.1 22.2
TECHNICAL NOTE
---~._.i--- 1 ~ 38
I
,
I 4
,
I
J
8
I
,
12
I
J
16
1 20
MINUT[S
Figure 1. Mean (+- SD) temperature in the sulcus omasi and abomasum after drinking cold (2°C) water. (Drink averaged 2.2 min.)
2473
region after drinking (c. 16 liters) cold water. Changes o f t e m p e r a t u r e at the a b o m a s u m followed a similar trend, but depression of temperature was m u c h less. This m a y have been caused by m o d u l a t i o n of the t e m p e r a t u r e by close p r o x i m i t y of probe to tissue or larger v o l u m e of fluid in this segment o f the gut. K r z y w a n e k and Lampe (6) observed that cons u m p t i o n of 500 ml o f cold water by sheep depressed abomasal t e m p e r a t u r e , especially when preceded directly by a meal. This agrees with Phillipson and Ash (8), who observed surges of cold fluid through the o m a s u m during or immediately after drinking. Regular fluctuation of sulcus omasi t e m p e r a t u r e after drinking sometimes was observed and m a y have resulted f r o m contractions of the reticulorumen. Trial 2
RESULTS A N D DISCUSSION Trial 1
Feed compositions are in Table 1. Because of variation of stage of lactation (range, 47 to 274 days) and milk p r o d u c t i o n (range, 11.5 to 41.5 kg/day) ratios of f o r a g e : c o n c e n t r a t e varied f r o m 55:45 to 95:5. Mean t e m p e r a t u r e response curves of abomasum and sulcus omasi for three cows following initiation o f drinking are in Figure t. Rapid and sustained depression of t e m p e r a t u r e in the sulcus omasi indicated bypass of water to this
It was anticipated that withholding water for a longer t i m e (9 vs. 4.5 h) w o u l d increase the a m o u n t of water that the cow would drink within the 15 rain in which it was m a d e available and that this, in turn, might increase the a m o u n t of water bypassing the reticulorumen. Results show (Table 2) that water c o n s u m p t i o n was significantly greater for cows deprived of water for 9 h versus 4.5 h; however, bypass of water was greatest when water deprivation was for only 4.5 h (18% versus 5% o f water consumed). This is c o n t r a r y to our e x p e c t a t i o n and m a y have been due to fill of the r e t i c u l o r u m e n
TABLE 2. Effect of water deprivation on water consumption and water bypass of the reticulorumen. Treatment 1 Water deprivation for 4.5h Measure Water intake, liters 3 Percent byp ass 2 Rumen dry matter, kg Rumen fluid volume, liters Total rumen contents, kg Rumen fluid dilution rate, %/h Rumen fluid outflow, liters/h
9h
X
SE
X
SE
24 18 11.2 73 84 13 9.6
8.6 3.7 .52 4.8 5.0 1.1 .87
38** 5 ** 10.0 81" 91 17513.8 t
6.2 3.4 .68 6.5 7.2 2.3 2.4
1Paired comparison: TP<.10, *P<.05, **P<.01. 2Percent of drinking water calculated to bypass the reticulorumen. 3Water consumption within 15 mln period after being offered. Journal of Dairy Science Vol. 67, No. 10, 1984
2474
WOODFORD ET AL. n o t be a s s u m e d to e q u i l i b r a t e with r u m i n a l fluid. More research is n e e d e d to clarify possible d i e t a r y or effects of r u m i n a l fill o n r u m i n a l w a t e r bypass.
tOO o
so
~o $ S cc 4 0
REFERENCES
g o
0
2
4 6 HOURS POSTFEEDING
8
Figure 2. Cumulative water consumption (-+ SD) as a percentage of total intake between feedings.
b e i n g g r e a t e r f o r cows o n t h e 4.5 h t r e a t m e n t prior to d r i n k i n g w a t e r ( t o t a l r u m i n a l c o n t e n t s m i n u s w a t e r c o n s u m e d = 59.9 kg at 4.5 h versus 52.4 kg at 9 h). W a r n e r a n d S t a c y (14) calculated t h a t f r o m .1 to .8 liters of d r i n k i n g w a t e r b y p a s s e d t h e r e t i c u l o r u m e n in 13 o f 20 experim e n t s w i t h sheep d r i n k i n g a f t e r feeding. Daily c o n s u m p t i o n o f w a t e r was p r e d i c t e d f r o m i n t a k e o f d r y m a t t e r a n d milk p r o d u c t i o n b y t h e e q u a t i o n of M u r p h y et al. (7). T h e port i o n of this e x p e c t e d to b e d r u n k a f t e r w a t e r w i t h h e l d f o r 4.5 a n d 9 h was e s t i m a t e d f r o m w a t e r i n t a k e b e t w e e n feedings (Figure 2) t o b e 31.2 a n d 39.2 liters, respectively. P r e d i c t e d 9-h i n t a k e agrees well w i t h m e a n w a t e r c o n s u m p t i o n o f 38.4 liters at t h a t time. P r e d i c t e d 4.5 h i n t a k e was h i g h e r t h a n m e a n w a t e r c o n s u m p t i o n , 24.0 liters; h o w e v e r , t h e r e was a large s t a n d a r d e r r o r for w a t e r c o n s u m p t i o n at 4.5 h. Increased w a t e r c o n s u m p t i o n o n t h e 9-h t r e a t m e n t was a c c o m p a n i e d b y increased rate o f fluid o u t f l o w f r o m r u m e n ( T a b l e 2). Effects o f e m p t y i n g , mixing, a n d replacing c o n t e n t s o n d i l u t i o n rate of r u m i n a l fluid have n o t b e e n examined; however, comparison of predicted daily w a t e r i n t a k e w i t h fluid o u t f l o w f r o m t h e r u m e n suggests t h a t i n t a k e r e p r e s e n t e d 34 a n d 23% of o u t f l o w f o r 4.5 a n d 9 h t r e a t m e n t s , respectively. These p e r c e n t s are m u c h less t h a n t h e 80% of Rogers et at. (12) in l a c t a t i n g cows o n a 75% c o n c e n t r a t e diet, b u t similar t o t h e 37 a n d 39% r e p o r t e d b y (3, 11, 13). R u m i n a l b y p a s s in l a c t a t i n g cows d r i n k i n g relatively large a m o u n t s o f w a t e r c o u l d a f f e c t comparisons of water intake with total ruminal fluid o u t f l o w as m e a s u r e d b y d i l u t i o n of a water-soluble marker. Drinking water should Journal of Dairy Science Vol. 67, No. 10, 1984
1 Association of Official Analytical Chemists. 1975. Official methods of analyses. 12th ed. Washington, DC. 2 Chen, M. M., K. R. Holmes, and V. Rupinskas. 1981. Pulse-decay method for measuring the thermal conductivity of living tissues. J. Biomech. Eng. 103:253. 3 Davis, C. L., D. A. Grenawalt, and G. C. McCoy. 1983. Feeding value of pressed brewers grains for lactating dairy cows. J. Dairy Sci. 66:73. 4 Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses. USDA Agric. Handbook 379, Washington, DC. 5 Faichney, G. J., D. E. Beever, and J. L. Black. 1981. Prediction of the fractional rate of outflow of water from the rumen of sheep. Agric. Systems 6:261. 6 Krzywanek, F. W., and W. Lampe. 1932. Ueber den flussigkeitstransport durch die varmagen des schafes. Dtsch. Tierarztl. Wochenschr. 40:289. 7 Murphy, M. R., C. L. Davis, and G. C. McCoy. 1983. Factors affecting water consumption by Holstein cows in early lactation. J. Dairy Sci. 66 : 35. 8 Phillipson, A. T., and R. W. Ash. 1965. Physiological mechanisms affecting the flow of digesta in ruminants. Page 97 in Physiology of digestion in the ruminant. R. W. Dougherty, ed. Butterwotths, London. 9 Poppi, D. P., D. J. Minson, and J. H. Ternouth. 1981. Studies of cattle and sheep eating leaf and stem fractions of grasses. II. Factors controlling the retention of feed in the reticulo-rumen. Aust. J. Agric. Res. 32:109. 10 Reid, C.S.W. 1965. Quantitative studies of digestion in the reticulo-rumen. I. Total removal and return of digesta for quantitative sampling in studies of digestion in the reticulo-rumen of cattle. Proc. N.Z. Soc. Anita. Prod. 25:65. 11 Rogers, J. A., and C. L. Davis. 1982. Rumen volatile fatty acid production and nutrient utilization in steers fed a diet supplemented with sodium bicarbonate and monensin. J. Dairy Sci. 65:944. 12 Rogers, J. A., C. L. Davis, and J. H. Clark. 1982. Alteration of rumen fermentation, milk fat synthesis, and nutrient utilization with mineral salts in dairy cows. J. Dairy Sci. 65:577. 13 Rogers, J. A., B. C. Marks, C. L. Davis, and J. H. Clark. 1979. Alteration of rumen fermentation in steers by increasing rumen fluid dilution rate with mineral salts. J. Dairy Sci. 62:1599. 14 Warner, A.C.I., and B. D. Stacy. 1968. The fate of water in the rumen. 2. Water balances throughout the feeding cycle in sheep. Br. J. Nutr. 22:389. 15 Watson, R. H. 1944. Studies on deglutition in sheep. Bull. Conc. Sci. Ind. Res. 180:1.
Bypass of Drinking
W a t e r in L a c t a t i n g C o w s 1 S. T. WOODFORD, = M. R. MURPHY, = C. L. DAVIS, = and K. R. HOLMES 3 University of Illinois Urbana 61801
ABSTRACT
assumptions that 1) water consumed by mature ruminants equilibrates with that in the reticulorumen, and 2) net transruminal water flux is minimal, has been used to relate water consumption to total ruminal fluid outflow (12). Rogers et al. (12) reported 80% of fluid leaving the reticulorumen of lactating cows was accounted for by water intake. Similar measurements of steers led to 43% (13). These observations suggest either alteration of salivary flow in association with higher feed intake (12) or significant ruminal bypass (water that does not equilibrate with that in the rumen) of drinking water in lactating cows. Ruminal bypass of drinking water has been described in sheep that after drinking a known amount of water had a higher than expected concentration of water-soluble marker in theii" rumen (.14). This phenomenon also has been reported by (6, 15) in which ruminal water bypass was related to ruminal fill at time of drinking.
Drinking water that does not equilibrate with ruminal fluid, i.e., bypasses the rumen, was studied qualitatively and quantitatively in eight rumen-fistulated lactating Holstein cows. Decreased temperatures in the sulcus omasi and abomasum shortly after initiation of drinking indicated that water had bypassed the rumen. Recovery of a water-soluble marker, included in drinking water offered after water was withheld for 4.5 or 9 h following feeding, was used to estimate ruminal bypass. For respective treatments, 18 and 5% of drinking water was calculated to have bypassed the rumen. Ruminal bypass in lactating cows drinking relatively large amounts of water could affect comparisons of water intake with total ruminal fluid outflow as measured by dilution of a water-soluble marker. Drinking water should not be assumed to equilibrate with ruminal fluid.
MATERIALS AND METHODS
INTRODUCTION
Passage of water through the reticulorumen is an important component of digestion. In addition to its metabolic functions, water also serves as a vehicle for digesta transport out of the rumen (5, 9). Saliva, ingested water, and fluid movement across the reticulorumen wall contribute to calculations of net water flow (]0). Dilution of water soluble markers often is used to estimate ruminal fluid volume and outflow. This technique, based on the underlying
Received February 2, !984. t Supported by lllinois Agricultural Experiment Station, Hatch 35-0360. z Department of Dairy Science. 3Deparmaent of Veterinary Biosciences. 1984 J Dairy Sci 67:2471-2474
In Trial 1 temperatures of abomasum and sulcus omasi were monitored qualitatively to examine ruminal bypass of water after drinking. A second trial was designed to provide a quantitative estimate of water bypass by measuring recovery of an orally consumed marker from the rumen. Trial 1
Eight multiparous rumen-fistulated Holstein cows, approximately 630 kg and in middle to late lactation, were fed 2.0 kg (dry matter) alfalfa hay daily, corn silage, and alfalfa haylage (50:50 dry matter) for ad libitum intake and high moisture corn and mineral supplemented soybean meal to production. Cows were fed at 1200 and 1530 h. A 2-wk adjustment preceded the trial. Animals were stanchioned except for milking at 0500 and 1500 h and allowed to exercise from 0600 to 1130 h. Water was available at all times.
2471
2472
WOODFORD ET AL.
Thermistor bead temperature probes (P25BA202N; Thermometrics Inc., Edison, N J) were used to measure temperature in the abomasum and sulcus omasi during and after consumption of cold water. The temperature probe was soldered to wire leads and connections, and probe were coated in epoxy, except for the probe tip, which was exposed. Our temperature measuring circuit was modified from Chen et al. (2). Temperature changes then were calculated from each probe's circuit output to a two channel chart recorder (2). A perforated rubber flange (10 cm diameter) was placed 20 cm from the terminal thermistor "A". A second thermistor, "B", was placed 8 cm behind the flange. On the day of measurement at 1200 h the probe assembly was inserted through the rumen fistula, and the rubber flange and probe "A" were placed in the abomasum which positioned probe "B" in the sulcus omasi. An X-ray was taken to verify probe placement in a Holstein steer. Water (2°C) was offered, on demand, from 26-liter containers via a gravity fed 2 cm diameter tube leading to the animal's drinking cup. Abomasal and sulcus omasal temperatures were recorded until they stabilized after consumption of water.
Trial 2
Cows and diets were the same as in Trial 1. Milking and feeding occurred at 0500 and 1500 h and 0530 and 1530 h, respectively. Otherwise animals were kept stanchioned to prevent access to unmetered water.
Animals were assigned randomly to treatments in which water was withheld for either 4.5 h or 9 h after 0500 h. After 7 days treatments were reversed. Water containing 3.8 g/ liter polyethylene glycol (PEG, M r 4000) was offered as in Trial 1. Samples of water were taken during delivery for PEG analysis. An animal was allowed to consume water containing PEG for 15 min at the appropriate time (0930 or 1400 h) after which the rumen was emptied immediately. Contents were weighed, mixed by hand, and duplicate samples were taken for dry matter and PEG analyses. Ruminal contents then were replaced, which completed this part of the procedure. Removal and replacement of contents of the rumen required about 45 min. Seven hourly fluid samples were taken from several points in the rumen by perforated tube/ suction flask to estimate dilution rate of ruminal fluid. Twice during the experiment when the cows were not being used for bypass measurements, hourly water intakes were measured on six cows between 0530 and 1530 h. Ruminal fluid was centrifuged at 12,000 × g for 15 min and supernatant frozen for analysis. Dry matter content of rumen was determined on samples dried at 55°C. Polyethylene glycol was measured as outlined by Rogers et al. (12). Feed samples were analyzed for crude protein, ether extract, ash (1), and acid detergent fiber (4). Percent of consumed water that bypassed the rumen was estimated by recovery of PEG in rumen contents. Three animals did not drink on both treatments; therefore, data from these animals were not used. Statistical analysis of the data was by a paired comparison between treatments (SAS Institute, Cary, NC).
TABLE 1. Composition of feedstuffs.
High Component
Alfalfa hay
Haylagesilage
moisture corn
Soybean meaP
Dry matter, %
90.0
50.9
81.5
91.5
Crude protein Acid detergent fiber Ether extract Ash
17.7 45.4 4.2 8.4
11.0 40.0 5.1 8.5
(% of dry matter)
1Includes trace mineral salt. Journal of Dairy Science Vol. 67, No. 10, 1984
9.4 4.2 4.3 1.5
45.6 8.0 1.1 22.2
TECHNICAL NOTE
---~._.i--- 1 ~ 38
I
,
I 4
,
I
J
8
I
,
12
I
J
16
1 20
MINUT[S
Figure 1. Mean (+- SD) temperature in the sulcus omasi and abomasum after drinking cold (2°C) water. (Drink averaged 2.2 min.)
2473
region after drinking (c. 16 liters) cold water. Changes o f t e m p e r a t u r e at the a b o m a s u m followed a similar trend, but depression of temperature was m u c h less. This m a y have been caused by m o d u l a t i o n of the t e m p e r a t u r e by close p r o x i m i t y of probe to tissue or larger v o l u m e of fluid in this segment o f the gut. K r z y w a n e k and Lampe (6) observed that cons u m p t i o n of 500 ml o f cold water by sheep depressed abomasal t e m p e r a t u r e , especially when preceded directly by a meal. This agrees with Phillipson and Ash (8), who observed surges of cold fluid through the o m a s u m during or immediately after drinking. Regular fluctuation of sulcus omasi t e m p e r a t u r e after drinking sometimes was observed and m a y have resulted f r o m contractions of the reticulorumen. Trial 2
RESULTS A N D DISCUSSION Trial 1
Feed compositions are in Table 1. Because of variation of stage of lactation (range, 47 to 274 days) and milk p r o d u c t i o n (range, 11.5 to 41.5 kg/day) ratios of f o r a g e : c o n c e n t r a t e varied f r o m 55:45 to 95:5. Mean t e m p e r a t u r e response curves of abomasum and sulcus omasi for three cows following initiation o f drinking are in Figure t. Rapid and sustained depression of t e m p e r a t u r e in the sulcus omasi indicated bypass of water to this
It was anticipated that withholding water for a longer t i m e (9 vs. 4.5 h) w o u l d increase the a m o u n t of water that the cow would drink within the 15 rain in which it was m a d e available and that this, in turn, might increase the a m o u n t of water bypassing the reticulorumen. Results show (Table 2) that water c o n s u m p t i o n was significantly greater for cows deprived of water for 9 h versus 4.5 h; however, bypass of water was greatest when water deprivation was for only 4.5 h (18% versus 5% o f water consumed). This is c o n t r a r y to our e x p e c t a t i o n and m a y have been due to fill of the r e t i c u l o r u m e n
TABLE 2. Effect of water deprivation on water consumption and water bypass of the reticulorumen. Treatment 1 Water deprivation for 4.5h Measure Water intake, liters 3 Percent byp ass 2 Rumen dry matter, kg Rumen fluid volume, liters Total rumen contents, kg Rumen fluid dilution rate, %/h Rumen fluid outflow, liters/h
9h
X
SE
X
SE
24 18 11.2 73 84 13 9.6
8.6 3.7 .52 4.8 5.0 1.1 .87
38** 5 ** 10.0 81" 91 17513.8 t
6.2 3.4 .68 6.5 7.2 2.3 2.4
1Paired comparison: TP<.10, *P<.05, **P<.01. 2Percent of drinking water calculated to bypass the reticulorumen. 3Water consumption within 15 mln period after being offered. Journal of Dairy Science Vol. 67, No. 10, 1984
2474
WOODFORD ET AL. n o t be a s s u m e d to e q u i l i b r a t e with r u m i n a l fluid. More research is n e e d e d to clarify possible d i e t a r y or effects of r u m i n a l fill o n r u m i n a l w a t e r bypass.
tOO o
so
~o $ S cc 4 0
REFERENCES
g o
0
2
4 6 HOURS POSTFEEDING
8
Figure 2. Cumulative water consumption (-+ SD) as a percentage of total intake between feedings.
b e i n g g r e a t e r f o r cows o n t h e 4.5 h t r e a t m e n t prior to d r i n k i n g w a t e r ( t o t a l r u m i n a l c o n t e n t s m i n u s w a t e r c o n s u m e d = 59.9 kg at 4.5 h versus 52.4 kg at 9 h). W a r n e r a n d S t a c y (14) calculated t h a t f r o m .1 to .8 liters of d r i n k i n g w a t e r b y p a s s e d t h e r e t i c u l o r u m e n in 13 o f 20 experim e n t s w i t h sheep d r i n k i n g a f t e r feeding. Daily c o n s u m p t i o n o f w a t e r was p r e d i c t e d f r o m i n t a k e o f d r y m a t t e r a n d milk p r o d u c t i o n b y t h e e q u a t i o n of M u r p h y et al. (7). T h e port i o n of this e x p e c t e d to b e d r u n k a f t e r w a t e r w i t h h e l d f o r 4.5 a n d 9 h was e s t i m a t e d f r o m w a t e r i n t a k e b e t w e e n feedings (Figure 2) t o b e 31.2 a n d 39.2 liters, respectively. P r e d i c t e d 9-h i n t a k e agrees well w i t h m e a n w a t e r c o n s u m p t i o n o f 38.4 liters at t h a t time. P r e d i c t e d 4.5 h i n t a k e was h i g h e r t h a n m e a n w a t e r c o n s u m p t i o n , 24.0 liters; h o w e v e r , t h e r e was a large s t a n d a r d e r r o r for w a t e r c o n s u m p t i o n at 4.5 h. Increased w a t e r c o n s u m p t i o n o n t h e 9-h t r e a t m e n t was a c c o m p a n i e d b y increased rate o f fluid o u t f l o w f r o m r u m e n ( T a b l e 2). Effects o f e m p t y i n g , mixing, a n d replacing c o n t e n t s o n d i l u t i o n rate of r u m i n a l fluid have n o t b e e n examined; however, comparison of predicted daily w a t e r i n t a k e w i t h fluid o u t f l o w f r o m t h e r u m e n suggests t h a t i n t a k e r e p r e s e n t e d 34 a n d 23% of o u t f l o w f o r 4.5 a n d 9 h t r e a t m e n t s , respectively. These p e r c e n t s are m u c h less t h a n t h e 80% of Rogers et at. (12) in l a c t a t i n g cows o n a 75% c o n c e n t r a t e diet, b u t similar t o t h e 37 a n d 39% r e p o r t e d b y (3, 11, 13). R u m i n a l b y p a s s in l a c t a t i n g cows d r i n k i n g relatively large a m o u n t s o f w a t e r c o u l d a f f e c t comparisons of water intake with total ruminal fluid o u t f l o w as m e a s u r e d b y d i l u t i o n of a water-soluble marker. Drinking water should Journal of Dairy Science Vol. 67, No. 10, 1984
1 Association of Official Analytical Chemists. 1975. Official methods of analyses. 12th ed. Washington, DC. 2 Chen, M. M., K. R. Holmes, and V. Rupinskas. 1981. Pulse-decay method for measuring the thermal conductivity of living tissues. J. Biomech. Eng. 103:253. 3 Davis, C. L., D. A. Grenawalt, and G. C. McCoy. 1983. Feeding value of pressed brewers grains for lactating dairy cows. J. Dairy Sci. 66:73. 4 Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses. USDA Agric. Handbook 379, Washington, DC. 5 Faichney, G. J., D. E. Beever, and J. L. Black. 1981. Prediction of the fractional rate of outflow of water from the rumen of sheep. Agric. Systems 6:261. 6 Krzywanek, F. W., and W. Lampe. 1932. Ueber den flussigkeitstransport durch die varmagen des schafes. Dtsch. Tierarztl. Wochenschr. 40:289. 7 Murphy, M. R., C. L. Davis, and G. C. McCoy. 1983. Factors affecting water consumption by Holstein cows in early lactation. J. Dairy Sci. 66 : 35. 8 Phillipson, A. T., and R. W. Ash. 1965. Physiological mechanisms affecting the flow of digesta in ruminants. Page 97 in Physiology of digestion in the ruminant. R. W. Dougherty, ed. Butterwotths, London. 9 Poppi, D. P., D. J. Minson, and J. H. Ternouth. 1981. Studies of cattle and sheep eating leaf and stem fractions of grasses. II. Factors controlling the retention of feed in the reticulo-rumen. Aust. J. Agric. Res. 32:109. 10 Reid, C.S.W. 1965. Quantitative studies of digestion in the reticulo-rumen. I. Total removal and return of digesta for quantitative sampling in studies of digestion in the reticulo-rumen of cattle. Proc. N.Z. Soc. Anita. Prod. 25:65. 11 Rogers, J. A., and C. L. Davis. 1982. Rumen volatile fatty acid production and nutrient utilization in steers fed a diet supplemented with sodium bicarbonate and monensin. J. Dairy Sci. 65:944. 12 Rogers, J. A., C. L. Davis, and J. H. Clark. 1982. Alteration of rumen fermentation, milk fat synthesis, and nutrient utilization with mineral salts in dairy cows. J. Dairy Sci. 65:577. 13 Rogers, J. A., B. C. Marks, C. L. Davis, and J. H. Clark. 1979. Alteration of rumen fermentation in steers by increasing rumen fluid dilution rate with mineral salts. J. Dairy Sci. 62:1599. 14 Warner, A.C.I., and B. D. Stacy. 1968. The fate of water in the rumen. 2. Water balances throughout the feeding cycle in sheep. Br. J. Nutr. 22:389. 15 Watson, R. H. 1944. Studies on deglutition in sheep. Bull. Conc. Sci. Ind. Res. 180:1.