Biomedical subjects

M A Froetschel

Publications and source records attributed to M A Froetschel.

At least 19 recordsLinked to original sources

PubMed2004

Effect of supplemental L-lysine-HCL and corn source on rumen fermentation and amino acid flow to the small intestine.

Four lactating Jersey cows fitted with ruminal and duodenal cannulae were used in a 4 x 4 Latin square design trial to determine the effect of supplemental lysine in diets containing dry ground (GC) or steam-flaked (SFC, 360 g/L) corn on ruminal fermentation and amino acid (AA) flow to the duodenum. Supplemental L-lysine-HCL provided 10 g/d of additional Lys to the total mixed rations. There were no interactions between supplemental Lys and corn source. Supplemental Lys increased Lys intake, but did not alter nutrient intake and digestibility or N flow to the duodenum. Intake of dry matter (DM), organic matter (OM), and neutral detergent fiber (NDF) and ruminal digestibility of starch tended to be higher, whereas ruminal digestibility of DM, OM, acid detergent fiber, and NDF was lower for diets supplemented with SFC compared with GC. Whole-tract digestibility was similar for both corn supplements. Ruminal pH and molar proportions of volatile fatty acids were not affected by supplemental Lys or corn source; however, ruminal NH(3) concentrations were lowest when SFC was fed. Intake of N tended to be higher and the flow of total N and individual AA to the duodenum was higher for diets supplemented with SFC. There was a trend for increased flow of microbial N for diets supplemented with SFC. Supplemental L-lysine-HCL did not alter ruminal fermentation, flow of amino acid to the small intestine, or nutrient digestibility, but feeding SFC reduced ruminal fiber digestion and increased microbial protein synthesis and flow of amino acid to the duodenum.

Amino Acids↗

PubMed2001

Opioid and cholecystokinin antagonists alleviate gastric inhibition of food intake by premeal loads of casein in meal-fed rats.

This study was undertaken to determine whether casein, compared with its constituent amino acids, given at the onset of a meal, would influence intake due to cholecystokinin (CCK) or opioid activity. Male Sprague-Dawley rats (n = 80; 225 g) were given either premeal loads of casein or its constituent amino acids and treated with opioid or CCK antagonists in a 2 x 4 factorially designed experiment. During a 21-d period, rats were meal-fed by restricting access to food to 5 h/d. The rats were fed the AIN-93 diet with soy isolate substituted for casein as the dietary protein source. On d 7-21, rats were given oral premeal loads of 5 mL of a 50 g/L casein or constituent amino acid solution before meal-feeding. On d 14-21, 20 rats were injected intraperitoneally with one of the following treatments: saline, naltrexone (l mg/kg), naloxone methiodide (5 mg/kg) or lorglumide (1 mg/kg) before the premeal load and feeding. Antagonist treatments increased intake (P < 0.05) by 15.3% compared with saline treatment (7.82 vs. 9.02 g/d) in rats given premeal loads of casein. Intake of rats given premeal loads of amino acids was not influenced by antagonists. At 2 h after feeding on d 21, the rats were killed, bled and eviscerated. Effects of antagonists on stomach and intestinal mass, digesta contents and fecal output were also dependent on the type of premeal load, indicating that gastric retention of digesta due to casein was mediated by CCK and opioids. Body weight accretion, liver, and epididymal fat mass and blood concentrations of specific amino acids changed in the same manner as intake (P < 0.05). Serum insulin was greater (P < 0.05) in casein-treated rats and reduced (P < 0.01) by opioid antagonists. Satiety associated with premeal loads of casein is related to changes in gastrointestinal function of meal-fed animals and involves both opioid and CCK regulation.

Amino Acids↗

PubMed1998

Effects of fish meal and sodium bentonite on daily gain, wool growth, carcass characteristics, and ruminal and blood characteristics of lambs fed concentrate diets.

We evaluated the effects of replacing some soybean meal (SBM) protein with fish meal (FM) protein in diets adequate and slightly deficient in CP, with or without .75% sodium bentonite (NaB) on performance and ruminal and blood metabolites of individually fed Suffolk lambs. Diets were based on corn, SBM, and cottonseed hulls. In Exp. 1, five lambs were assigned to each of the three dietary treatments (11% CP with 3% FM, 13% CP with 0 or 3% FM). Lambs fed diets that contained 11% CP with 3% FM or 13% CP with 0% FM had similar DMI and ADG. Gain and feed efficiency were slightly improved (P = .18) by the 13% CP diet with 3% FM. In Exp. 2, 32 lambs were assigned to four dietary treatments (13.5% CP of DM) in a 2 x 2 factorial arrangement (0 or 3% FM, and 0 or .75% NaB on an as-fed basis). The DMI and ADG were increased (P < .05) by FM and NaB supplementation. Interactions (P < .05) revealed that NaB increased DMI, ADG, gain per feed (g/kg of DMI), and plasma urea N concentration in the absence of FM but not in the presence of FM in the diet. Neither FM nor NaB influenced (P = .25) wool growth. Total ruminal VFA were increased (P < .06) by FM and NaB. Differences in mineral content of phalanx bone, liver, and kidney were small and may be related to the mineral content of diets and the effect of NaB on mineral solubilities. Similar DMI and ADG of lambs fed FM and NaB separately and in combination suggest that their beneficial effect is not additive.

Animal Feed↗

PubMed1998

Effects of fiber from tropical corn and forage sorghum silages on intake, digestion, and performance of lactating dairy cows.

Tropical corn silage was compared with sorghum silage as a basal forage in the diets of high producing dairy cows. Sorghum and tropical corn silages were each included in place of ground corn at incremental concentrations in the experimental diets. Eight separate diets were fed, four diets containing each silage ranging in forage neutral detergent fiber (NDF) from approximately 25 to 31% and ranging in total NDF from approximately 41 to 45%. Diets were arranged in a 2 x 4 factorial design and were fed to lactating cows (n = 24; pretrial mean milk production = 39 kg/d; body weight = 656 kg; and days in milk = 81). As concentrations of dietary NDF increased, intake and milk production decreased linearly. The impact of dietary NDF on intake was greater for diets based on tropical corn silage than for diets based on sorghum silage. Energy intake and milk production were reduced, but cows consumed more fiber when challenged with higher dietary concentrations of fiber. The in vitro rate and extent of digestion of dietary samples were correlated with intake response. The rate of in vitro fiber digestion was slower for samples that contained tropical corn silage than for samples that contained sorghum silage. In vivo digestibility measurements were influenced by intake and dietary composition. Results of this trial indicated that sorghum silage can have equal or slightly greater nutritional value than tropical corn silage when these forages are fed at equal concentrations of dietary fiber.

Animal Feed↗

PubMed1998

Biogenic amines in silage, apparent postruminal passage, and the relationship between biogenic amines and digestive function and intake by steers.

A 4 x 4 Latin square experiment was conducted to examine abomasal passage of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of the dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substituted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to four ruminally and abomasally cannulated steers. The roughage component of the diet constituted 50% of the DM and consisted of 60% alfalfa silage or hay and 40% tropical corn silage. The concentrate was composed mainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentration in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines was 5 to 20% of intake. Abomasal recovery of cadaverine was correlated with depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of reticular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in steers fed diets that contained more alfalfa silage. Ruminal fluid pH and NH3 concentration increased in steers fed more alfalfa silage; however, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabolism of biogenic amines is extensive based on the relatively low quantities recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated physiological effects.

Abomasum↗

PubMed1997

Opioid-mediated responses of dietary protein on reticular motility and plasma insulin.

Four ruminally and abomasally cannulated steers (603 +/- 22.7 kg of body weight) were used to determine whether ruminally undegradable protein (RUP) would exert opioid-mediated effects on reticuloruminal motility or circulating concentrations of insulin. Steers were fed isonitrogenous diets (16% crude protein) containing either 30 or 40% RUP. The low RUP diet was supplemented with urea and soybean meal, and the high RUP diet was supplemented with blood meal, fish meal, corn gluten meal, and meat and bone meal. Diets contained 57% wheat silage and were fed twice daily at 0800 and 1600 h. Experimental periods were 10 d in length. Blood samples were taken from jugular catheters, and reticular motility was measured at hourly intervals on d 10 over a 16-h period. Either naltrexone (0.5 mg/kg of body weight) or saline was infused into the abomasum at the second feeding (9 h). Naltrexone reduced the frequency of reticular contractions by 16.5% for steers fed the low RUP diet. Naltrexone decreased the duration of reticular contractions by 9.3% for steers fed the low RUP diet and increased duration by 8.7% for steers fed the high RUP diet. Naltrexone decreased the opening time of the reticuloomasal orifice, expressed as a percentage of predose measurements, by 16.3% for steers fed the high RUP diet. Insulin was 21.3% higher with the high RUP diet. The postprandial rise in insulin decreased 36.7% with naltrexone. Dietary protein can exert effects mediated by opioids in ruminants.

Animal Feed↗

PubMed1996

Bioactive peptides in digesta that regulate gastrointestinal function and intake.

Exorphins, a particular class of biologically active peptides that exist within a protein sequence, are released during digestion, absorbed intact, and modulate gastrointestinal motility, secretions, endocrine metabolism, and possibly intake by binding to specific opioid receptors. Casomorphins are a class of exorphin from milk protein that slows gastric motility and emptying in nonruminants. In the mature ruminant, abomasal infusion of casein, 1.25 to 5.0% (wt/vol) for 3 h at 16.7 mL/min, linearly decreased reticular contraction frequency 3.5 to 5.1%, duration 2.0 to 4.0%, and amplitude 5.8 to 15.5% from the control (P < .05). This effect was blocked by intragastric administration of the opioid antagonist naltrexone (.5 mg/kg of BW). Abomasal infusion of an acid hydrolysate of casein exerted more immediate effects on reticular motility that were amplified by administration of the opioid antagonist. Dual excitatory-inhibitory responses are characteristic of opioid regulation. Naltrexone-reversible effects on reticular motility, reticular-omasal orifice opening, and post-prandial insulin rise were also demonstrated when a ruminally undegradable protein supplement containing blood meal, fish meal, corn gluten meal, and meat and bone meal was fed. The effects of opioid peptides on digesta passage and postprandial insulin rise implicate their potential involvement with intake regulation. Saliva is another source of bioactive peptides. Abomasal infusion of saliva (1.5 L/h) linearly increased reticular contraction frequency 2.5 to 7.7% and ruminal dilution rate 33.8% from the control (P < .05). Bioactive peptides may provide new dietary methods for improving productive efficiency of livestock.

Animals↗

PubMed1996

Seasonal effects of supplemental fat or undegradable protein on the growth and metabolism of Holstein calves.

One summer (heat stress) and one winter (neutral conditions) trial were conducted to assess the effects of varied amounts of RUP and fat on the growth and metabolic responses of calves. In each trial, 190-kg Holstein calves (n = 45) were fed a basal diet of corn and cottonseed hulls supplemented with soybean meal (control) or supplemented with raw or roasted whole soybeans or the basal ration plus prilled hydrogenated tallow either with or without a mixture of feather meal and blood meal. Prilled tallow was more detrimental to fiber digestion and growth performance than were whole soybeans, especially during summer. During winter, calves fed a high (49%) percentage of the dietary CP as RUP had similar BW gain and efficiency of feed usage as did calves fed a moderate percentage (39%), but, during summer, calves fed the high percentage of RUP had greater BW gain and efficiency than did calves fed moderate percentages of RUP. Ruminal concentrations of VFA were parallel to digestibilities of fiber in the total tract. Ruminal concentrations of ammonia or blood concentrations of urea were not consistent with the concentrations of RDP fed. Concentrations of glucose, NEFA, insulin, and thyroid hormones in the blood were primarily affected by season. Data suggested that a higher percentage and AA quality of RUP improved the growth of calves during summer but not during winter.

Ammonia↗

PubMed1995

Influence of duodenal slaframine infusion on site of nutrient disappearance from the digestive tract of steers fed a high-concentrate diet.

The effect of duodenal slaframine (SF) infusion on site and extent of digestion was determined using four steers equipped with ruminal, duodenal, and ileal cannulas in a 4 x 4 Latin square. A 77% dry-rolled corn diet was provided in 12 equal portions daily at a DMI of 2.26% BW. Slaframine in a .9% saline excipient was infused into the duodenum every 12 h with total daily dose of 0, 30, 60, or 90 micrograms /kg of BW. Slaframine infusion had no effect on ruminal pH, ruminal NH3 N, or solids and liquids passage rate. Slaframine increased (linear, P < .10) total tract OM and starch disappearance and digestibility and tended to increase (linear, P = .14) total tract N digestibility. Ruminal starch disappearance tended to be decreased (quadratic, P = .16) by SF. Small intestinal OM digestibility was increased (linear, P < .10) but starch digestibility in the small intestine was not affected by SF. Increased total tract starch digestibility was caused by increased (quadratic, P < .10) starch fermentation in the large intestine. Ruminal feed N digestibility decreased at the intermediate doses of SF (quadratic, P < .10). Total N digestibility in the small intestine tended to be increased (cubic, P = .13) with 30 and 90 micrograms of SF/kg of BW. Decreased ruminal feed N digestion was compensated for by increased (quadratic, P < .10) small intestinal feed N disappearance for steers treated with intermediate doses of SF. The potential of SF to increase starch digestion in the rumen and small intestine seems to be limited.

Alkaloids↗

PubMed1995

The involvement of slaframine and swainsonine in slobbers syndrome: a review.

The history of "slobbers syndrome," a mycotoxicosis associated with Rhizoctonia leguminicola infestation of pastures and stored forages, is discussed. The chemistry and physiological effects of the two known biologically active alkaloids of R. leguminicola, slaframine and swainsonine, are described. Slaframine administration is generally associated with increased exocrine function, especially salivation. Ingestion of swainsonine may be linked to serious and potentially lethal central nervous system defects similar to that described for locoism. However, the singular effects of these alkaloids do not completely account for the total clinical picture noted in the field during the occurrence of slobbers syndrome. It is possible that this phenomenon is the result of an interaction between both known and unidentified biologically active metabolites of R. leguminicola.

Alkaloids↗

PubMed1995

Effects of inoculation and wilting on the preservation and utilization of wheat forage.

Wheat forage was harvested at an early head stage of maturity and ensiled in 12 900-kg experimental silos at three percentages of DM (20.8% for direct-cut forage and 27.9 or 39.3% for wilted forage) either with or without application of a lactic acid bacterial inoculant. The objective was to test the efficacy of the inoculant to alter silage fermentation, preservation, and nutritive value of wheat forage ensiled at different moisture percentages because of wilting. Wilting enhanced DM preservation and decreased fermentation end products. Inoculation made the fermentation more homolactic but did not enhance DM preservation. Silage rations (80% DM as silage) were fed at 1.8% of BW/d to six ruminally and abomasally fistulated steers (350 kg) in an experiment with a Latin-square design and a 3 x 2 factorial arrangement of treatments. Digestive responses to silage diets were not influenced by inoculation. Intake was depressed with direct-cut silage rations. Wilting improved fiber digestibility and was associated with changes in ruminal contents and fermentation end products. Wilting appears to be more effective than inoculation as a postharvest management tool to improve small grain silage.

Animal Feed↗

PubMed1995

Effect of abomasal infusion of saliva on reticular motility and ruminal liquid contents of steers.

Two Holstein and two Jersey steers with ruminal and abomasal cannulas were used in a 4 x 4 Latin square experiment to test the effects of abomasal infusion of saliva on reticular contractions and on contents of the reticulorumen. Steers were fed a ration based on sorghum silage (58.3% DM) at 2-h intervals in 12 equal amounts at 1.25 times the maintenance requirement. Saliva was collected from eight esophageally fistulated steers, pooled, and stored frozen at -20 degrees C. Saliva was mixed with McDougall's buffer (0, 33.3, 66.7, or 100% saliva) and infused abomasally at a rate of 1.5 L/h for 3 h. Abomasal infusion of saliva resulted in linear decreases in ruminal liquid and DM contents. Ruminal dilution rate tended to be faster for infused steers as concentration of saliva increased. Frequency of reticular contractions increased linearly as saliva infusion increased. The influence of saliva infusion on duration of reticular contractions was complicated by inverse patterns of response for each separate phase of the reticular contraction. The first phase of the contraction was influenced by saliva infusion in a negative, quadratic manner; the second phase exhibited an opposite response pattern. A quadratic effect was evident for both amplitude and area of contractions, indicating that the contraction strength was decreased at the intermediate salivary infusion. Postruminal passage of saliva may influence ruminal digestive function by regulating reticular motility and digesta passage.

Abomasum↗

PubMed1995

Responses of early lactation cows fed winter and summer annual forages and undegradable intake protein.

Twenty-four multiparous Holstein cows were divided into six blocks of 4 cows based on their previous 305-d mature equivalent milk yield and were used in a 2 x 3 factorial experiment for the first 84 DIM. Objectives were to determine the effects of forage and RUP supplementation of DM and nutrient intakes and digestibilities, milk yield and composition, BW change, and plasma concentrations of insulin, triiodothyronine, thyroxine, cortisol, NEFA, urea N, and protein. One cow from each block was assigned to wheat or sorghum silage plus one of three concentrates. Protein treatments were 1) all supplemental CP from soybean meal; 2) 33.3% of supplemental CP from heat soybean meal, fish meal, and corn gluten meal; and 3) protein treatment 2 plus an additional 4.6% CP from soybean meal. Intakes of DM, CP, NDF, ADF, NEL, and RUP were higher in cows fed sorghum silage; RUP tended to increase DMI. Milk and 3.5% FCM yields were higher for cows fed sorghum silage than for those fed wheat silage (42.3 vs. 40.0 kg/d and 41.2 vs. 38.7 kg/d, respectively). Milk protein, lactose, and SNF were increased by RUP. Insulin was increased, cortisol was decreased, and thyroid hormones were unaffected by RUP. Concentrations of NEFA were highest at wk 4. For early lactation cows fed diets containing sorghum or wheat silage, RUP is a necessity.

Animal Feed↗

PubMed1994

Involvement of opioid peptides from casein on reticular motility and digesta passage in steers.

Experiment 1 determined the effects of incremental abomasal casein infusion on reticular motility and digesta passage of mature steers in a 4 x 4 Latin square study. Casein solutions were infused at 0, 1.25, 2.5, and 5.0% (wt/vol) for 3 h at 16.7 ml/min. Steers were fed for maintenance every 2 h. Casein resulted in a linear decrease in frequency, duration, and amplitude of reticular contractions measured manometrically. Total area of reticular contractions from physiographic tracings decreased 10.4 to 18.5%. Ruminal DM contents decreased 4.5 to 7.5%. Experiment 2 characterized the effects of casein on reticular contractions to be mediated by opioid peptides. Steers were infused abomasally (4 h) with either a 5% (wt/vol) solution of casein or its hydrolysate with or without a predose of naltrexone as an opiate antagonist (.5 mg/kg of BW) in a 2 x 2 factorial. Both casein and hydrolysate reduced frequency and duration of reticular contractions. Hydrolysate decreased contraction frequency within 30 min of infusion and 60 min prior to effects of casein. Naltrexone reversed the effects of casein and accentuated the effects of hydrolysate. Ruminal liquid outflow was decreased 19.7% with hydrolysate. Postruminal infusion of casein or its hydrolysate resulted in casomorphin-like activity on reticular motility and digesta passage.

Abomasum↗

PubMed1993

Effects of supplemental protein source on ruminal fermentation, protein degradation, and amino acid absorption in steers and on growth and feed efficiency in steers and heifers.

In Exp. 1, four Holstein steers with cannulas in the rumen, abomasum and terminal ileum were used to determine the effects of 1) soybean meal (SBM), 2) heated SBM (HSBM), 3) corn gluten meal (CGM), or 4) a combination of HSBM and CGM (COMBO) as protein supplements on ruminal and total tract nutrient digestibilities and intestinal amino acid flows and absorption. In Exp. 2, 24 Holstein steers and 16 Holstein heifers were used in a 56-d growth trial to study the effects of these protein supplements on growth, feed efficiency, and apparent digestibility of DM, OM, CP, and fiber components. Increasing undegradable intake protein (UIP) in diets with HSBM, CGM, and COMBO decreased ruminal fluid ammonia N concentrations (P < .05) and ruminal DM and OM digestion (P < .05) and increased flow to the abomasum and absorption from the small intestine of CP (P < .05), total amino acids (P < .05), and total essential amino acids (P < .01). Increasing UIP increased bacterial and nonbacterial CP and amino acids flowing to the abomasum (P < .05). However, UIP supplementation did not affect DMI, ADG, or feed efficiency in steers or heifers (P < .05).

Amino Acids↗

PubMed1993

Effects of supplemental protein source on intraruminal fermentation, protein degradation, and amino acid absorption.

Cannulated steers were used to determine the effects of supplemental soybean meal, heated soybean meal, fish meal, and a combination of fish meal, heated soybean meal, and corn gluten meal on intraruminal protein degradation and absorption of AA from the small intestine. Organic matter digestion in the reticulo-rumen was greater in steers fed diets supplemented with soybean meal, but whole tract digestibility was not affected by protein source. Total and bacterial CP flows to the abomasum were lower in steers fed diets supplemented with fish meal than in steers fed diets supplemented with heated soybean meal or the combination supplement. Dietary CP flow was 33.5% higher in steers fed diets supplemented with heated soybean meal than in steers fed diets supplemented with soybean meal, fish meal, or the combination supplement. Less essential and nonessential AA flowed to the abomasum and were absorbed from the small intestine of steers receiving diets supplemented with soybean meal. Digestibility of small intestine AA was 21.9% lower in steers receiving the soybean meal treatment. Abomasal flows of Met and Thr and absorption of Lys, Met, and Thr were increased in steers fed diets containing heated soybean meal, fish meal, and the combination supplement. These results suggest that the supply of AA deficient in microbial CP (Lys, Met, and Thr) can be increased and that absorbed AA balance can be changed markedly by selection of rumen escape protein supplements.

Amino Acids↗

PubMed1991

Effects of dietary fiber and feeding frequency on ruminal fermentation, digesta water-holding capacity, and fractional turnover of contents.

To determine the effects of different sources of fiber and feeding frequency on digesta water-holding capacity (WHC; g H2O/g DM) and ruminal liquid contents, four ruminally fistulated Jersey steers were fed a 60:40 roughage-concentrate diet at 1.5 times NEm. Diets contained either sorghum silage (SS) or a 67:33 mixture of SS and soyhulls (SH) as roughage and were fed either once or 12 times daily, in a 2 x 2 factorial experiment with 15-d periods. Ruminal fluid was sampled at 2, 4, 6, 8, 10, 12, 16, 20, and 24 h after a dose of Co-EDTA on d 10 and analyzed for Co, VFA, ammonia, buffering capacity, and osmolality. Ruminal WHC, NDF, ADF, lignin, and starch were measured in samples obtained by ruminal evacuation at 3, 6, 12, and 24 h after feeding on d 11, 12, 14, and 15, respectively. Substitution of SH for SS decreased ruminal pH .32 units and dilution rate by 26.8% but increased total VFA by 10.9%, osmolality by 13.6%, and the fractional turnover rate (FTR) of ADF by 22.5% (P less than .05). Frequent feeding resulted in 4.7, 21.9, and 74.4% increases in total VFA and FTR of ruminal DM and starch (P less than .05), respectively. Interactions (P less than .05) were observed between dietary fiber source and feeding frequency for ruminal fluid molar percentage acetate to propionate ratio (A/P), liquid volume (evacuated), and WHC (kilograms). Substituting SH for SS decreased ruminal WHC (kilograms), liquid volume, and A/P only in steers fed once daily. Ruminal WHC (kilograms) was correlated positively with ruminal liquid volume but negatively with DM FTR. The dynamics of digesta WHC (kilograms) associated with dietary fiber source and feeding frequency suggest that it may influence the contribution of water and salivary secretions to ruminal liquid contents.

Animal Feed↗

PubMed1991

Effects of additives and growth environment on preservation and digestibility of wheat silage fed to Holstein heifers.

Wheat grown in two separate years under different environmental conditions was fed as silage to investigate effects of additives on forage preservation and digestibility. Direct-cut wheat was harvested in an early head stage of maturity. Wheat was drought stressed in yr 1 and averaged 41.6% DM, and yr 2 averaged 23.0% DM at harvest. Forage was ensiled in 10 900-kg concrete stave silos; 2 per year were assigned to one of five treatments consisting of control, treatment with an enzyme-chemical product, or treatment with one of three different types of lactic acid bacterial inoculants. Each year, during two 12-d periods, forage from five different silos was fed individually for ad libitum intake, separate from concentrate (1.1% of BW) to 15 Holstein heifers (average BW 228 +/- 32 kg). Wheat forage and silage from yr 1 was lower in CP but higher in NDF, ADF, lignin, and starch than that harvested in yr 2. Silage additives decreased DM and NDF recovery in yr 1 and increased DM, NDF, and neutral detergent solubles recovery in yr 2. Additives increased the ratio of lactic to acetic acid and decreased ammonia in silage both years. Additives increased DM and fiber digestibilities of wheat silage-based rations fed to Holstein heifers in yr 2. In vitro digestibility indicated that these improvements were associated with a reduction in the lag phase of forage digestion. The rate of in vitro DM digestibility was positively correlated with silage DM recovery, suggesting an association with nutrient preservation. Wheat preservation and digestibility both were improved by silage additives when wheat was grown under normal environmental conditions, but losses were greater with additives in drought-stressed forage.

Animals↗