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PubMed2003

Pelleted beet pulp substituted for high-moisture corn: 3. Effects on ruminal fermentation, pH, and microbial protein efficiency in lactating dairy cows.

The effects of increasing concentrations of dried, pelleted beet pulp substituted for high-moisture corn on ruminal fermentation, pH, and microbial efficiency were evaluated using eight ruminally and duodenally cannulated multiparous Holstein cows in a duplicated 4 x 4 Latin square design with 21-d periods. Cows were 79 +/- 17 (mean +/- SD) DIM at the beginning of the experiment. Experimental diets with 40% forage (corn silage and alfalfa silage) and 60% concentrate contained 0, 6.1, 12.1, or 24.3% beet pulp substituted for high-moisture corn on a DM basis. Diet concentrations of NDF and starch were 24.3 and 34.6% (0% beet pulp), 26.2 and 30.5% (6% beet pulp), 28.0, and 26.5% (12% beet pulp), and 31.6 and 18.4% (24% beet pulp), respectively. Substituting beet pulp for corn did not affect daily mean or minimum ruminal pH but tended to reduce pH range. Ruminal acetate:propionate responded in a positive exponential relationship to added beet pulp. Rate of valerate absorption from the rumen was not affected by treatment. Substituting beet pulp for corn up to 24% of diet DM did not affect efficiency of ruminal microbial protein production, expressed as microbial N flow to the duodenum as a percentage of OM truly digested in the rumen. Microbial efficiency was not correlated to mean pH or daily minimum pH. While microbial efficiency was not directly related to concentration of beet pulp fed, it was positively correlated with passage rate of particulate matter, as represented by starch and indigestible NDF, probably due to reduced turnover of microbial protein in the rumen.

Animal Feed↗
PubMed2004

Grain processing, forage-to-concentrate ratio, and forage length effects on ruminal nitrogen degradation and flows of amino acids to the duodenum.

The objectives of this study were to evaluate effects of dietary factors that alter ruminal fermentability on rumen N degradation, microbial protein synthesis, duodenal flows, and digestibility of amino acids (AA) in the intestines and the total tract. The experiment was a double 4 x 4 quasi-Latin square with a 2(3) factorial arrangement of treatments. The dietary factors were extent of barley grain processing, coarse (processing index; PI = 75.5%) or flat (PI = 60.2%); forage-to-concentrate (F:C) ratio, low (35:65) or high (55:45) on a DM basis; and forage particle length (FPL), long (7.59 mm) or short (6.08 mm). Eight lactating cows with ruminal and duodenal cannulas were offered ad libitum access to a total mixed diet. There were no significant interactions between dietary treatments for ruminal N degradation or its duodenal flow and digestibility in the intestines. Passage of microbial protein to the duodenum was improved with increased F:C ratio of the diet but was not affected by grain processing or FPL. Ruminal digestibility of N was increased with increased F:C ratio (49 vs. 60%) and with reduced FPL (59 vs. 50%). Increased grain processing improved N digestibility both in the intestine (15%) and in the total tract (8%). Reduction in the FPL of the diets reduced intestinal N digestion by 14% without affecting the N digestion in the total tract. Increased extent of grain processing tended to enhance duodenal flows of AA. In contrast, reducing FPL lowered flows of dietary AA to the duodenum because of lowered flows of feed plus endogenous N. Increased F:C ratio of the diet did not change the flow of total AA, but there was a reduced flow of dietary AA and increased flow of microbial AA. Flows of several individual AA were increased by feeding flatly rolled barley with limited effects of F:C ratio or FPL. An interaction between grain processing and FPL was detected for flows of some AA. Diets formulated with flatly rolled barley plus long FPL increased Arg, Thr, Asp, Glu, Ser, Tyr, and nonessential AA (NEAA) by more than 24%, compared with other combinations of grain processing and FPL. Digestibility of essential AA (EAA) in the intestine (68%) was higher than that of NEAA (63%), but digestion of total AA (65%) was similar to that of total N (66%). Digestibilities of individual AA in the intestine ranged from 46 to 77% and were generally improved with increased grain processing. However, effects of F:C ratio or FPL on digestion of AA were limited. These results indicate that manipulation of dairy cow diets can improve ruminal N degradation, microbial protein synthesis, flows of AA to the duodenum, and intestinal digestibility of AA. Combining dietary factors can be more beneficial than changing individual dietary factors for improving the delivery of AA to the small intestine.

Amino Acids↗
PubMed2005

Ruminal fermentation and amino acid flow in Holstein steers fed whole cottonseed with elevated concentrations of free fatty acids in the oil.

The influence of feeding whole cottonseed (WCS) containing elevated concentrations of free fatty acids (FFA) in the oil on ruminal fermentation and amino acid (AA) flow to the abomasum was evaluated in a 4 x 4 Latin square trial. Four ruminally and abomasally cannulated Holstein steers were fed diets containing 12.5% of dry matter as WCS with concentrations of 8.0, 11.3, 14.7, or 18.0% FFA in the oil. Intake, ruminal digestibility, and flow to the abomasum of dry matter, organic matter, and acid detergent fiber were not affected by FFA level of WCS. Intake of neutral detergent fiber and total kilograms of neutral detergent fiber digested in the rumen were similar for all treatments. Ruminal neutral detergent fiber digestibility was lower for 8 and 14.7% FFA, resulting in a cubic effect on flow to the abomasum. Ruminal pH, molar proportions of isobutyrate, and total branched-chain volatile fatty acids (VFA) decreased linearly, whereas molar proportions of acetate and acetate:propionate ratio increased linearly as FFA in WCS increased. Total VFA were lower, and molar proportions of propionate were higher, for 8 and 14.7% FFA, resulting in a cubic effect. Intake of N, total N flow, and nonmicrobial N flow to the abomasum were similar among treatments. Flow of microbial N was lower for the 11.3% FFA treatment, resulting in a quadratic response. Only nonsignificant differences were observed in AA flow to the abomasum. Results of this trial indicate that WCS with FFA up to 18% may result in small changes in rumen fermentation.

Abomasum↗
PubMed2005

Varying protein and starch in the diet of dairy cows. I. Effects on ruminal fermentation and intestinal supply of nutrients.

The main objective of this experiment was to examine the effects of the percentage and source of crude protein (CP) and the amount of starch in the diet of dairy cows on ruminal fermentation, nutrient passage to the small intestine, and nutrient digestibility. For this purpose, 6 multiparous Holstein cows fistulated in the rumen and duodenum that averaged 73 d in milk were used in a 6 x 6 Latin square design with a 2 x 3 factorial arrangement of treatments. Two sources of CP [solvent-extracted soybean meal (SBM) and a mixture of SBM and a blend of animal-marine protein supplements plus ruminally protected Met (AMB)] and 3 levels of dietary protein (about 14, 16, and 18%) were combined into 6 treatments. On a dry matter (DM) basis, diets contained 25% corn silage, 20% alfalfa silage, 10% cottonseed, 26.7 to 37% corn grain, and 4 to 13.5% protein supplement. Intakes and digestibilities in the rumen and total tract of DM, organic matter, acid and neutral detergent fiber were unaffected by treatments. Increasing dietary CP from 14 to 18% decreased the intake and apparent ruminal and total tract digestion of starch, but increased the proportion of starch consumed by the cows that was apparently digested in the small intestine. At 14% CP, starch intake and total tract digestion were higher for the AMB diet than for the SBM diet, but the opposite occurred at 16% CP. Across CP sources, increasing CP in the diet from 14 to 18% increased the intakes of N and amino acids (AA), and ruminal outflows of nonammonia N, nonammonia nonmicrobial N, each individual AA except Met, total essential AA, and total AA. Across CP percentages, replacing a portion of SBM with AMB increased the intake of Met and Val and decreased the concentration of ammonia N in the rumen, but did not affect the intake of other essential AA or the intestinal supply of any essential AA and starch. The ruminal outflow of microbial N, the proportional contribution of Lys and Met to total AA delivered to the duodenum, and milk yield were unaffected by treatments. Data suggest that the intake of N by high-producing dairy cows that consume sufficient energy and other nutrients to meet their requirements can be decreased to about 600 to 650 g daily without compromising the supply of metabolizable protein if the source and amount of dietary CP and carbohydrate are properly matched.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Physically effective fiber: method of determination and effects on chewing, ruminal acidosis, and digestion by dairy cows.

A study was conducted to investigate the effects of physically effective neutral detergent fiber (peNDF) content of dairy cow diets containing corn silage as the sole forage on intake, chewing, ruminal pH, microbial protein synthesis, digestibility, and milk production. A second objective was to compare current methods of measuring peNDF to determine the most suitable approach for use in ration formulation. The experiment was designed as a replicated 3 x 3 Latin square using 6 lactating dairy cows with ruminal cannulas. Diets varied in peNDF content (high, medium, and low) by altering the particle length of corn silage. The physical effectiveness factors (pef) and peNDF contents of the corn silage and diets were determined based on the original (19- and 8-mm sieves) and new Penn State Particle Separator (PSPS; 19-, 8-, and 1.18-mm sieves). A dry-sieving technique that measures the proportion of particles retained on a 1.18-mm sieve was also used. The new PSPS and the 1.18-mm sieve produced similar estimates of pef and peNDF of diets but gave higher values than the original PSPS. There was a much smaller range in pef of corn silage when 3 sieves, rather than 2, were used with the PSPS (range of 0.93 to 0.96 vs. 0.41 to 0.72, respectively). Consequently, increased forage particle length in the diets increased dietary peNDF content and its intake when using the original PSPS; however, the new PSPS and the 1.18-mm sieve failed to detect changes in dietary peNDF and peNDF intake. The peNDF values estimated based on fractional NDF rather than the total NDF content were higher, but the ranking of diets was not changed. Increased intake of peNDF linearly increased digestibility of CP and tended to linearly increase digestibility of fiber in the total tract. As a result, milk yield tended to linearly increase with no effect on milk composition. Ruminal microbial protein synthesis and microbial efficiency were higher with the medium peNDF than with the high or low peNDF diets. Total chewing time and ruminating time were linearly increased with increasing dietary peNDF, whereas influence of dietary peNDF on ruminal pH and fermentation was minimal. This study showed that increasing peNDF content of diets improved fiber digestion. Of the systems used to measure peNDF, the original PSPS provided a good description of dietary particle length and its effects on chewing time and rumen pH, whereas the new PSPS provided a more consistent chewing index, the ratio of total chewing activity to peNDF, across diets varying in chop length of corn silage.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Effects of addition of essential oils and monensin premix on digestion, ruminal fermentation, milk production, and milk composition in dairy cows.

Four ruminally cannulated, lactating Holstein cows were used in a 4 x 4 Latin square design (28-d periods) with a 2 x 2 factorial arrangement of treatments to study the effects of dietary addition of essential oils (0 vs. 2 g/d; EO) and monensin (0 vs. 350 mg/d; MO) on digestion, ruminal fermentation characteristics, milk production, and milk composition. Intake of dry matter averaged 22.7 kg/d and was not significantly affected by dietary additives. Apparent digestibilities of dry matter, organic matter, neutral detergent fiber, and starch were similar among treatments. Apparent digestibility of acid detergent fiber was increased when diets were supplemented with EO (48.9 vs. 46.0%). Apparent digestibility of crude protein was higher for cows fed MO compared with those fed no MO (65.0 vs. 63.6%). Nitrogen retention was not changed by additive treatments and averaged 27.1 g/d across treatments. Ruminal pH was increased with the addition of EO (6.50 vs. 6.39). Ruminal ammonia nitrogen (NH3-N) concentration was lower with MO-supplemented diets compared with diets without MO (12.7 vs. 14.3 mg/100 mL). No effect of EO and MO was observed on total volatile fatty acid concentrations and molar proportions of individual volatile fatty acids. Protozoa counts were not affected by EO and MO addition. Production of milk and 4% fat-corrected milk was similar among treatments (33.6 and 33.4 kg/d, respectively). Milk fat content was lower for cows fed MO than for cows fed diets without MO (3.8 vs. 4.1%). The reduced milk fat concentration in cows fed MO was associated with a higher level of trans-10 18:1, a potent inhibitor of milk fat synthesis. Milk urea nitrogen concentration was increased by MO supplementation, but this effect was not apparent when MO was fed in combination with EO (interaction EO x MO). Results from this study suggest that feeding EO (2 g/d) and MO (350 mg/d) to lactating dairy cows had limited effects on digestion, ruminal fermentation characteristics, milk production, and milk composition.

Animals↗
PubMed2006

Rumen lipopolysaccharide and inflammation during grain adaptation and subacute ruminal acidosis in steers.

Three rumen-fistulated Jersey steers were gradually adapted to a wheat-barley concentrate over a 4-wk period. Adaptation steps consisted of four 1-wk periods during which steers were fed diets with forage-to-concentrate (F:C) ratios of 100:0, 79:21, 59:41, and 39:61. The forage consisted of chopped hay (CH), and the concentrate consisted of pelleted concentrate containing 50% ground wheat and 50% ground barley. Steers were fed the all-forage diet ad libitum during wk 1. Feed offered in wk 2 to 4 was kept constant at the ad libitum intake during wk 1. On 2 d that were set 3 d apart during wk 5, subacute ruminal acidosis (SARA) was induced in the steers by feeding a diet with an F:C ratio of 24:76 by offering them 0.9 kg of CH at 0900 h followed by 2 meals of 3.0 kg each of wheat-barley pellets (WBP) at 1100 h and 1300 h and 0.9 kg of CH at 1700 h, to depress rumen pH for at least 3 h/d below 5.6. The average concentrate inclusion for the SARA induction diet was 76 +/- 10% DM. During stepwise adaptation, time with pH below 5.6 increased to an average of 121 min/d when the steers were consuming a diet containing 61% DM as WBP. Dietary inclusion of WBP at the rate of 76% DM induced SARA because the steers spent an average of 219 min/d with pH below 5.6. The free ruminal lipopolysaccharide (LPS) concentration increased from 6,310 endotoxin units (EU)/mL with the all-forage diet to 18,197 EU/mL with the 61% concentrate diet. The ruminal LPS concentration increased to 26,915 EU/mL when SARA was induced. Serum haptoglobin increased from 0.53 mg/mL when steers were on the all-forage diet to 1.90 mg/mL with the 61% concentrate diet and were not increased further by inducing SARA. The serum amyloid-A concentration was not affected by increasing dietary concentrate during stepwise adaptation to the concentrate, but increased from 71 to 163 microg/mL when SARA was induced. A gradual increase in dietary concentrate so that the F:C ratio decreased to 39:61 resulted in increased ruminal LPS concentrations. Subsequent induction of SARA further increased ruminal LPS and activated an inflammatory response.

Acidosis↗
PubMed1976

Effects of adrenalectomy upon ruminant liver and mammary function during lactation.

Adrenalectomized, lactating ewes treated with a mineral corticoid or a mineral corticoid plus cortisol and sham operated ewes nursing one or two lambs were in a study of physiological role(s) of glucocorticoids in lactating ruminants. Measurements of ewe and lamb weight changes; feed intake; milk yield and composition; blood potassium; metabolite oxidation rates by mammary, liver, and kidney tissue slices; glucose production in liver and kidney tissue slices; and enzyme activities in mammary and liver tissue. 1) Mammary metabolism and milk biosynthesis in ruminants are not strongly dependent on glucocorticoid. 2) Liver gluconeogenesis in ruminants appears to be regulated in part by glucocorticover and kidney of ruminants may respond differently to adrenalectomy; thus, in ruminants, kidney may not be as good an indicator of liver gluconeogenic responses as it is in rodents. 4) Liver and mammary enzymes are not affected significantly by adrenalectomy or glucocorticoid therapy. 5) Glucocorticoids play a less significant role in the regulation of liver and mammary enzyme and metabolism in sheep than in rats.

Acetates↗
PubMed1979

Trace element deficiencies and fertility in ruminants: a review.

Various minerals (copper, cobalt, selenium, manganese, iodine, zinc, and iron) can influence reproductive performance of ruminants. Reproductive failure may be induced by deficiencies of single or combined trace elements and by imbalances. This review is focused on maladjustments of trace elements leading to impaired breeding performance. Opinion is diverse as to the existence of various reproductive disturbances from either a severe copper depletion or a marginal dietary copper deficiency. Field experience suggests that administration of cobalt to ruminants on cobalt-deficient diets improves their impaired breeding performance. Selenium infertility in ewes is more prevalent in some areas and in some seasons, but the actual cause of this malady and the continuing role of additional factors are unknown. Manganese is necessary for normal fertility in ruminants, and feeding low-manganese rations depresses conception rates. Lack of iodine impairs thyroid activity and also ovarian function. Reproductive failure in the female and in spermatogenesis are manifestations of zinc deficiency. Despite forages rich in iron, low availability in certain instances could affect adversely ruminant reproduction. Knowledge of biochemical dysfunctions from trace element deficiencies is essential to determine the role which trace elements play in fertility of ruminant animals.

Abortion, Veterinary↗
PubMed1984

Ruminal bypass of drinking water in lactating cows.

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.

Abomasum↗
PubMed1989

Effects of calcium carbonate on ruminal fermentation, nutrient digestibility, and cow performance.

Sixteen Holstein cows were used in a 4 x 4 Latin square design (four replicates) to investigate the effect of feeding calcium carbonate on feed intake, ruminal fermentation, apparent total tract nutrient digestibility, milk yield, and milk composition. Supplementation of calcium carbonate to diets that contained 60% concentrate and 40% corn silage (DM basis) decreased DM intake and milk production and was not effective in altering ruminal fluid pH, ruminal fluid dilution rate or outflow, molar proportions of ruminal fluid VFA, or synthesis of milk fat and milk protein by dairy cows. Calcium carbonate supplementation to the diet tended to improve efficiency of feed utilization (4% FCM/DM intake). The exact site of action of calcium carbonate, if any, is not known. However, these data suggest that calcium carbonate exerts little or no buffering effect in the rumen when the pH is 6 or above regardless of its reactivity rate in strong acid or its mean particle size. This lack of effect is probably because of its low solubility in ruminal fluid at pH above 5.5.

Animals↗
PubMed1990

Effects of centrifugation speed and freezing on composition of ruminal bacterial samples collected from defaunated sheep.

Triplicate ruminal samples from four rumen-cannulated defaunated sheep (50 kg BW) were used in a completely randomized design experiment with a 2 x 3 factorial arrangement of treatments to test effects of two pretreatments (fresh vs. freezing) and three centrifugation speeds (4640 x g for 30 min; 9820 x g for 20 min; 25,900 x g for 20 min) or quantity of ruminal bacteria harvested and composition of ruminal bacterial samples. There were no differences among centrifugation speeds on quantity of ruminal bacterial harvested, organic matter, total N, RNA, and diaminopimelic acid concentrations (% of DM), or RNA:N, RNA:organic matter, N:organic matter, and diaminopimelic acid:organic matter ratios. However, there were differences between fresh and frozen samples for all measurements except diaminopimelic acid concentration, and the diaminopimelic acid:organic matter ratio, suggesting that freezing ruminal fluid is not appropriate for obtaining truly representative bacterial samples.

Animals↗
PubMed1992

Feeding sequence and strategy effects on ruminal environment and production performance in first lactation cows.

Three primiparous cows were assigned randomly to a 4 x 4 incomplete Latin square to evaluate ruminal characteristics (Experiment 1) with the following feeding strategies: strategy A, supplement (protein), forage plus high moisture ear corn (energy), protein; strategy B, energy plus protein, forage, energy plus protein; strategy C, forage plus energy, protein, forage plus energy, protein; and strategy D, forage, energy plus protein, forage, energy plus protein. In Experiment 2, 36 cows were fed diets similar to those in Experiment 1 from wk 4 through 19 postpartum. Cows fed diets according to strategy A had the highest and strategy D the lowest mean ruminal pH. Diurnal variation in ruminal pH was less with cows fed diets using strategies A and B than C and D. Other ruminal parameters were not significantly different. In Experiment 2, cows fed according to strategy B had higher DMI than those fed according to other strategies. Energy and protein fed together and separately from forage, regardless of sequence, increased milk fat percentage compared with protein fed separately. Milk production and protein yield tended to be highest when protein was fed separately, regardless of sequence to forage. Strategic feeding of protein and energy sources in relation to forage influenced some ruminal and production measurements in primiparous cows.

Animal Feed↗
PubMed1993

In vitro and in vivo ruminal and physiological responses to endophyte-infected tall fescue.

Relationships between alkaloid compounds in endophyte-infected tall fescue and ruminal metabolism were studied in two experiments. In the first experiment, different combinations of the pyrrolizidine alkaloids, N-formyl and N-acetyl loline, were incubated with ruminal fluid for 0, 24, or 48 h. Rate of disappearance of N-formyl and N-acetyl loline increased over time. After 48 h, disappearance of N-formyl loline and combinations of N-formyl and N-acetyl loline was greater than N-acetyl loline. Significant amounts of N-formyl and N-acetyl loline were metabolized and converted to loline. In the second experiment, abomasally cannulated sheep were fed increasing amounts of endophyte-infected feed to compare diet digestibility, alkaloid metabolism, and physiological responses. Total tract DM digestibility was greatest for the endophyte-free diet, as were ruminal and total tract ADF, ruminal NDF, and total tract CP digestibilities. N-Formyl and N-acetyl loline recoveries averaged 5% from abomasal contents and 0% in feces. Sixty-eight percent of the pyrrolizidine alkaloids recovered in abomasal contents had been metabolizable to loline. Ergot alkaloids administered in the diet were recovered (50 to 60%) in the abomasal contents, but recovery was only 5% in fecal collections. No significant differences occurred in the physiological parameters measured. Results indicate that response to endophyte-infected tall fescue may be influenced by ruminal metabolism.

Acremonium↗
PubMed1993

Interactions of fiber and nonstructural carbohydrates on lactation and ruminal function.

Four Holstein cows averaging 147 DIM and fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square trial to determine diet effects on DMI, milk production, and ruminal metabolism. Diets contained either rapidly or slowly degraded NDF, referred to as low fill and high fill, respectively, combined with two percentages of nonstructural carbohydrate. Treatments were 39% nonstructural carbohydrate (low or high fill) and 29% nonstructural carbohydrate (low or high fill). Intake of DM was not affected by either fill or nonstructural carbohydrate. Ruminal NDF digestibilities averaged 43.1 and 35.6% for the low fill and high fill diets, respectively. Ruminally digested nonstructural and total carbohydrate increased, but milk production decreased, as nonstructural carbohydrate increased from 29 to 39% in diets. Liquid and solid ruminal passage rates, as measured by Co-EDTA and Yb, respectively, were reduced by either 39% nonstructural carbohydrate or low fill diets. Lower microbial N flow to the duodenum and lower efficiency of microbial growth also were observed for diets with 39% nonstructural carbohydrate. The combination of 39% nonstructural carbohydrate and rapidly degraded fiber gave the highest DM and nonstructural carbohydrate digestion in the rumen but resulted in low microbial N synthesis per day and the least microbial N per kilogram of OM digested.

Animal Feed↗
PubMed1993

Comparison of copper lysine and copper sulfate as copper sources for ruminants using in vitro methods.

Two in vitro experiments were conducted to estimate the availability of Cu from Cu Lys compared with Cu from CuSO4. In experiment 1, a 24-h ruminal fermentation (alpha-cellulose substrate) containing either .1% added S or 2% added urea was performed with 4, 12, or 96 ppm of added Cu as either Cu Lys or CuSO4. Soluble Cu was measured at the end of the 24-h incubation, and concentrations were higher for Cu Lys with added urea (1.16 vs. .45 ppm), but no differences existed between sources of added S. In Experiment 2, 20 ppm of Cu added as either Cu Lys or CuSO4 with and without the addition of 10 ppm of Mo and .75% S were used in an vitro study designed to simulate digesta passage through the ruminant. A 24-h ruminal fermentation (orchardgrass substrate) was followed by a 2-h digestion in pepsin and HCl (pH 2.3) and then a 2-h digestion in NaHCO3 and pancreatin (pH 6.6). Soluble Cu concentrations were analyzed after each step. Molybdenum and S addition decreased soluble Cu after ruminal fermentation and tended to decrease soluble Cu concentrations after digestion of pancreatin and NaHCO3. The source of Cu did not affect soluble Cu concentrations. Results suggest that Cu from Cu Lys and CuSO4 behave similarly in the digestive tract of ruminants.

Animals↗
PubMed1994

Lactational responses to ruminally undegradable protein by dairy cows fed diets based on alfalfa silage.

Lactational responses to protein supplementation of diets containing 60% of DM as alfalfa silage were evaluated. Sixty muliparous Holstein cows were fed a covariant diet for the first 3 wk postpartum, blocked by calving date, and randomly assigned for 14 wk to one of six isonitrogenous (19.4% CP) diets. Diets were formulated with soybean meal, a blend of animal by-products, or both, and contained 5.0, 5.6, 5.6, 6.2, 6.1, and 6.8% ruminally undegradable protein (DM basis). Percentage of ruminally undegradable protein or source of supplemental protein did not affect 3.5% FCM (39.4 kg/d), milk fat yield (1.38 kg/d), milk protein percentage (2.83%), milk urea (7.66 mM), or plasma urea (8.91 mM). However, cows fed diets supplemented with soybean meal had higher DMI (26.2 vs. 24.7 kg/d), milk yields (40.4 vs. 39.1 kg/d), and milk protein (1.15 vs. 1.09 kg/d) yields, but lower milk fat concentration (3.42 vs. 3.53%) and body condition score (2.85 vs. 2.93) than cows fed diets containing a blend of animal by-products. The lack of response to ruminally undegradable protein was partially caused by higher than predicted DMI (5 to 15% above NRC predictions); all diets provided at least 1.3 kg of ruminally undegradable protein, and there was no beneficial effect from ruminally undegradable protein intake increases to 1.6 kg/d.

Ammonia↗
PubMed1996

Ruminal degradation and dose response of dairy cows to dietary L-carnitine.

In Experiment 1, in vitro degradation of L-carnitine was measured in ruminal fluid obtained either from a cow that was fed a 75% concentrate diet or from a cow fed a control (50% forage and 3% fat) diet. Carnitine degradation was greater in ruminal fluid from the cow fed the control diet than in ruminal fluid from the cow fed the 75% concentrate diet and was more rapid in ruminal fluid obtained after 2 wk of adaptation to dietary carnitine supplementation (7 g/d). In Experiment 2, 20 multiparous Holstein cows were used in a replicated 5 x 5 Latin square design to determine the effects of increasing the amount of dietary L-carnitine (0, 0.875, 1.75, 3.5, or 7.0 g/d) that was fed to lactating dairy cows. All cows received the same diet, which contained 3% added fat. Carnitine concentration in milk and plasma increased linearly with carnitine supplementation. The DMI, milk yield, and milk composition were unaffected by carnitine. Apparent total tract digestibilities of NDF and fatty acids decreased quadratically as the amount of supplemented carnitine increased; generally, means were lowest when cows were fed 1.75 g/d of carnitine. The concentration of total VFA and molar percentages of individual VFA in ruminal fluid were unaffected by the amount of carnitine fed. Concentrations of glucose, NEFA, and urea N in plasma were unaffected by the amount of dietary carnitine; however, plasma cholesterol concentration decreased linearly as carnitine increased. Supplementation of < or = 7.0 g/d of dietary carnitine did not benefit DMI, milk yield, milk composition, or digestive measurements in this experiment.

Animals↗