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PubMed2002

Dried poultry waste for cows grazing low-quality winter forage.

Two trials conducted in 1996-97 measured BW and body condition score changes of cows fed different sources of degradable intake protein, including dried poultry waste and soybean meal, while grazing low-quality winter forages. In Trial 1, 60 spring-calving cows (5 yr; 555 kg) were used in an individual supplementation trial. Cows were gathered three times a week, sorted into individual pens, and fed their respective supplement. Cows grazed dormant native Sandhills winter range (common pasture) and were assigned to one of six supplemental treatments: 1) no supplement, 2) urea, 3) 22% dried poultry waste + urea, 4) soybean meal, 5) 22% dried poultry waste + soybean meal, or 6) 44% dried poultry waste. All supplements were based on wheat middlings and soybean hulls and were formulated to contain 44% CP. Thirty-six cows were selected randomly (six per treatment) for a 5-d measurement of forage intake from December 16 through December 20, 1996. Cows receiving supplements gained more weight (P < 0.001) and maintained greater body condition (P < 0.001) than unsupplemented cows. Cows receiving urea gained less (P < 0.10) than cows receiving a source of natural protein, but body condition remained similar. No differences were found in daily forage or total organic matter intake (P > 0.10). In Trial 2, cows grazed corn residues. Forty-eight spring-calving cows were group-fed supplements in one of six 4-ha paddocks. Cows received supplements containing either soybean meal or dried poultry waste that were the same as the soybean meal and 44% dried poultry waste supplements fed in Trial 1; gains were not different (P > 0.10). Under the economic conditions that existed at the time of these experiments, the supplement containing dried poultry waste resulted in a savings of $.04 per cow per day and a total savings of $3.20 per cow over an 80-d period. Feeding a supplement containing dried poultry waste resulted in performance similar to that when feeding a more conventional supplement containing soybean meal.

Animal Feed↗
PubMed2003

Supplementation to meet metabolizable protein requirements of primiparous beef heifers: I. Performance, forage intake, and nutrient balance.

Three experiments were conducted to evaluate the response of supplementing primiparous heifers based on the metabolizable protein (MP) system during pregnancy and lactation. In Exp. 1, 12 pregnant, March-calving heifers (432 +/- 10 kg) grazing Sandhills range were randomly allotted to one of two treatments: supplementation based on either the MP system (MPR) or the CP system (CPR). Supplements were fed to individual heifers from October to February and no hay was offered. Grazed forage organic matter intake (FOMI) was measured in November, January, and February. In Exp. 2, 18 heifers (424 +/- 8 kg) were randomly allotted to one of three treatments: 1) supplementation based on the MP system with hay fed in January and February (average 2.0 kg/d; MPR/hay), 2) supplementation based on the CP system, with hay fed in January and February (CPR/hay), or 3) supplementation based on the MP system, with no hay fed (MPR/no hay). Supplements were fed from October to February, and FOMI was measured in December and February. In Exp. 3, lactating 2-yr-old cows (394 +/- 7 kg) maintained on meadow hay were supplemented to meet either 1) MP requirements (LMPR) or 2) degradable intake protein requirements (LDIPR). Body weight (BW) and body condition score change, hay intake, and milk production were measured. In Exp. 1, grazed FOMI decreased (P = 0.0001) from 1.9% of BW in November to 1.2% in February, but no differences among treatments were detected for FOMI or BW change. In Exp. 2, grazed FOMI declined (P = 0.0001) from 1.7% of BW in December to 1.1% in February, with no differences among treatments. Heifers on the MPR/hay and CPR/hay treatments had higher (P = 0.0018) total intake (grazed forage + hay intake) in February (1.7% BW) than the MPR/no hay heifers (1.1% BW). Heifers on the MPR/no hay treatment had a lower weight (P = 0.02) and tended (P = 0.11) to have a lower BCS than heifers on other treatments. In Exp. 3, the LMPR cows had higher (P = 0.02) ADG than LDIPR cows (0.41 and 0.14, respectively), but treatment did not affect milk production. Organic matter hay intake averaged 2.4% of BW. We conclude that supplementation to meet MP requirements had little benefit to heifer performance during gestation, but increased weight change during lactation. Because grazed forage intake decreased from 1.9 to 1.1% of BW with advancing gestation, supplemental energy is necessary to reduce weight and condition loss of gestating hefiers grazing dormant Sandhills range.

Animal Feed↗
PubMed2003

Characterization of season and sampling method effects on measurement of forage quality in fescue-based pastures.

Information on seasonal changes and effects of sampling methods on the measurement of forage quality is limited for fescue-based pastures. Eight continuously grazed, 0.76-ha, fescue-based pastures were used to compare forage type, method of collection, and seasonal effects on forage quality in a repeated-measures, split-plot design. Four pastures were interseeded with red clover in March 2000. Masticate (M; from four ruminally cannulated steers) and hand--clipped (C) samples were collected every 28 d from April to October 2000. Interseeding red clover did not affect (P > 0.10) OM, CP, NDF, and ADF concentrations or CP degradability. Sampling method and season interacted (P < 0.03) for OM, CP, NDF, and ADF concentrations. Concentrations of OM averaged 5 percentage units more (P < 0.01) in C than in M in all months and were more variable with M than with C. Samples clipped between April and September averaged 5.5 percentage units greater NDF (P < 0.01), 3.0 percentage units greater ADF (P < 0.01), and 4.5 percentage units less CP (P < 0.01) than masticate samples obtained during the same time period. Fiber and CP concentrations did not differ (P > 0.10) between C and M samples obtained in October. Differences in CP degradability estimates (using Streptomyces griseus protease) between the two sample types were greater in late-season samples than in samples obtained from April to June. When S. griseus protein degradability estimates were compared with in situ estimates for masticate samples, no differences (P > 0.10) were detected early in the season (April to June). However, the S. griseus procedure overestimated in situ values (P < 0.01) by an average of 3 percentage units in samples obtained between July and October. Differences in composition of C and M samples were substantial until late season, when opportunities for selective grazing were minimal. Small differences between S. griseus and in situ estimates of CP degradability indicate that the S. griseus procedure can yield useful CP degradability estimates for fescue-based pasture samples. Although it might be possible to apply correction values to clipped samples to estimate CP and fiber concentrations of diets selected by grazing cattle, inconsistent relationships preclude this approach for estimates of CP degradability.

Animal Feed↗
PubMed2005

The effect of a condensed tannin-containing forage on methane emission by goats.

The objective of this study was to compare methane emission by goats consuming the condensed tannin-containing forage sericea lespedeza (Les-pedeza cuneata) or a mixture of crabgrass (Digitaria ischaemum) and Kentucky 31 tall fescue (Festuca arundinacea). Two groups of 12 Angora does (initial average BW = 41.5 +/- 2.7 kg) that previously grazed a pasture of sericea lespedeza or crabgrass/tall fescue for approximately 4 mo were used. After 1 wk of adaptation to metabolism cages, gas exchange was measured for 24 h in an open-circuit respiration calorimetry system with four head boxes. Forage harvested daily from the previously grazed pastures was consumed ad libitum. Crude protein concentration was 10.3 and 13.0%, IVDMD was 64.5 and 75.3%, and the level of condensed tannins was 17.7 and 0.5% for sericea lespedeza and crabgrass/tall fescue, respectively. Dry matter intake (1.11 vs. 0.67 kg/d) and digestible DMI (estimated from IVDMD; 0.71 vs. 0.51 kg/d) were greater (P < 0.01) for sericea lespedeza than for crabgrass/tall fescue. Ruminal ammonia N (3.7 and 9.9 mg/dL; P < 0.001) and plasma urea-N concentrations (16.7 and 20.9 mg/dL; P = 0.07) were lower for sericea lespedeza than for crabgrass/tall fescue. Concentrations of individual and total VFA and the acetate-to-propionate ratio in ruminal fluid did not differ between treatments (P > 0.19). Despite higher DMI by goats fed sericea lespedeza, daily energy expenditure (409 vs. 431 kJ/kg BW(0.75)), heart rate (70 vs. 73 beats/min), and the ratio of energy expenditure to heart rate (5.82 vs. 5.94) did not differ between sericea lespedeza and crabgrass/tall fescue, respectively (P > 0.13). Methane emission expressed as both quantity per day or relative to DMI was lower (P <0.001) for sericea lespedeza than for crabgrass/tall fescue (7.4 vs. 10.6 g/d and 6.9 vs. 16.2 g/kg DMI). Substantial differences between the forages in condensed tannins concentration and methane emission by Angora goats suggest that condensed tannins decreased methane emission.

Ammonia↗
PubMed1980

Effect of monensin on gain and forage utilization by calves grazing bermudagrass.

Two trials were conducted to determine the influence of monensin on live weight gain and efficiency of forage utilization of calves grazing Bermudagrass. In trial 1, 32 calves, weaned at an average age of 238 days and 250 kg, were grazed on "Coastcross I" Bermudagrass from July 20 to October 13. Eight steers and eight heifers were randomly assigned to one of two treatments: 200 mg monensin/head/day or 0 mg monensin/head/day fed in a .01 kg/head/day diet of pelletized 14% protein feed. Both groups were stocked at 15.3 head/ha. Monensin-fed calves gained .52 kg/head/day, while the control-fed calves gained .42 kg/head/day (P < .10). Average daily gains (ADG) of steers (.54 kg) were greater (P < .05) than those of heifers (.40 kg). Forage to gain ratio estimates were 15:1 and 19:1 for calves on monensin and control paddocks, respectively. In trial 2, 48 steer calves, averaging 265 days of age and 260 kg, were randomly assigned to each of two replicates of the following grazing treatments: common Bermudagrass only (P), Bermudagrass + .91 kg/head/day 14% protein feed (PF) or Bermudagrass + .91 kg/head/day feed + 200 mg monensin/head/day (PFM). ADG were .45, .47 and .68 kg for steers fed P, PF and PFM, respectively. The monensin-fed calves showed a 45% improvement in ADG (P < .05). Estimated forage to gain ratios for calves fed P, PF and PFM were 20:5:1, 19:1 and 13:1, respectively. The use of 200 mg monensin/head/day improved calf gains by 23 to 45% and increased estimated feed efficiencies by 21 to 36% on Bermudagrass pastures. The improvement in gain for heifers fed monensin was 28.6%, while steers gained 18.4% more when fed monensin.

Animal Feed↗
PubMed1989

Effects of a monensin ruminal delivery device on daily gain, forage intake and ruminal fermentation of steers grazing irrigated winter wheat pasture.

Two trials evaluated the effects of a monensin ruminal delivery device (MRDD) on steers grazing winter wheat pasture. In Trial 1, 60 Hereford steers (initial wt 238.5 kg) grazed a 21.9-ha paddock of Vona-variety winter wheat for 112 d. Steers were assigned to either MRDD or control (C) treatments in a randomized complete block design. In Trial 2, eight ruminally cannulated steers (avg wt 234.4 kg) grazed a 2.4-ha paddock of Vona-variety wheat and were assigned randomly to either MRDD or C treatments. Three 11-d collection periods were conducted during early February, early March and early April. Chromic oxide was dosed to determine fecal output, and ruminal samples were collected on d 6 of each period. Nylon bags containing ground wheat forage were incubated ruminally beginning on d 8. In Trial 1, steers with MRDD tended (P less than .11) to gain more weight than C steers (.44 vs .38 kg/d). In Trial 2, wheat forage intake, in situ DM disappearance, ruminal pH, ruminal ammonia concentrations and ruminal proportions of acetate and total VFA concentrations were not affected by treatment. Ruminal proportions of propionate were increased (P less than .05) slightly by MRDD (20.3 and 19.2 mol/100 mol for MRDD and C, respectively). Butyrate proportions in ruminal samples were decreased (P less than .05) by MRDD during March but not in other sampling periods. Ruminal fluid chlorophyll concentration was less (P less than .05) for MRDD-treated vs C steers during early March but was greater (P less than .10) for MRDD-treated steers during early April. The MRDD shows promise as a method of supplying monensin to cattle grazing winter wheat forage.

Animal Feed↗
PubMed2000

Rumen fermentation in lactating cows selected for milk fat content fed two forage to concentrate ratios with hay or silage.

Sixteen multiparous cows, including eight rumen fistulated cows, were used in a 4x4 Latin square experiment designed to study dietary effects on rumen and blood parameters and milk production in cows differing in genetic capacity for milk fat content. Diets contained forage to concentrate ratios of 50:50 or 30:70 with either grass hay or silage as the forage. Ruminal fermentation was characterized by a high molar percentage of butyrate, 14 to 17%. Forage to concentrate ratio affected most rumen parameters, with the exception of the molar percentage of propionate (18 to 19%). The silage had a higher fiber degradation rate compared with hay. Compared to hay diets, silage diets had higher ruminal outflow rates, lower acetate:propionate ratios, and greater milk production with no differences in milk composition. Cows selected for low milk fat had higher molar percentages of propionate in the rumen. The low milk fat cows had higher milk production than cows selected for high milk fat but did not differ in milk fat yield. Cows fed the 30:70 diets had higher plasma insulin concentrations in response to a glucose challenge. The low milk fat cows had lower basal concentrations of insulin and lower insulin responses to a glucose challenge. Small changes in nutrient metabolism and supply were sufficient to influence milk production.

Animal Feed↗
PubMed2002

Response of forage fiber degradation by ruminal microorganisms to branched-chain volatile fatty acids, amino acids, and dipeptides.

This study evaluated the effect of branched-chain volatile fatty acids (VFA; isobutyric acid, isovaleric acid), amino acids (valine, leucine), and dipeptides (valine-valine, leucine-leucine) on neutral detergent fiber (NDF) degradation by rumen microorganisms in vitro. The CP (%) and in situ NDF degradation rate (%/h) for alfalfa, bermudagrass, and pangolagrass hays, and napiergrass silage were 17.2 and 7.5, 4.7 and 3.1, 8.3 and 5.3, and 9.6 and 3.4, respectively. In vitro NDF digestibility was the lowest for bermudagrass; alfalfa and napiergrass were the highest. When the incubation contained more ammonia initially, digestibilities increased, but relative differences among forages were unchanged. Adding branched-chain VFA (2 mM) to incubations increased digestibilities more than controls on 15 out of 16 occasions. The effectiveness varied with isoacids and forages used. Amino acid (2 mM) or dipeptide (1 mM) addition consistently increased digestibility over controls. Amino acids further increased digestibility over corresponding isoacids on 14 occasions. Improvement in digestibility over control by leucine appeared to be greater than that by valine. Digestibilities with dipeptides were always greater than those with isoacids, except for one case. Dipeptide addition further increased digestibility significantly over corresponding amino acids on only six occasions, while percent improvement in digestibility numerically by dipeptides occurred in 10 cases. Valine-valine seemed to exert different effect than leucine-leucine, depending on initial ammonia availability. The results indicate that dipeptides could be more effective than isoacids and amino acids in improving NDF digestion. Forages with high CP content or rapid NDF degradation rate appeared to respond to additives to smaller degrees.

Amino Acids↗
PubMed2002

Effects of forage particle size and grain fermentability in midlactation cows. I. Milk production and diet digestibility.

Our study investigated the effects of, and interactions between, level of dietary ruminally fermentable carbohydrate (RFC) and forage particle size on milk production, nutrient digestibility, and microbial protein yield for dairy cows fed one level of dietary NDF. Eight cows (61 days in milk) were assigned to four treatments in a double 4 x 4 Latin square. Treatments were arranged in a 2 x 2 factorial design; finely chopped alfalfa silage (FS) and coarse alfalfa silage (CS) were combined with concentrates based on either dry cracked shelled corn (DC; low RFC) or ground high-moisture corn (HMC; high RFC). Diets were fed ad libitum as a total mixed rations with a concentrate to forage ratio of 61:39. Diets based on DC had a predicted NEL content of 1.73 Mcallkg dry matter (DM), while HMC diets contained 1.80 Mcal/kg DM. Diets averaged 18.7% CP, 24.0% NDF, 18.3% ADF, and 27.4% starch on a DM basis. Mean particle size of the four diets was 6.3, 2.8, 6.0, and 3.0 mm for DCCS, DCFS, HMCCS, and HMCFS, respectively. Increasing level of RFC decreased dry matter intake (DMI) from 25.0 to 23.8 kg/ d and organic matter intake from 22.3 to 21.1 kg/d, but intake was not affected by particle size. Milk production averaged 44.0 and 26.8 kg/d solids corrected milk (SCM) and was not affected by diet, but increasing level of RFC tended to increase milk yield. Efficiency of milk production, expressed as SCM/DMI, increased from 1.06 to 1.14 when level of RFC was increased. Milk composition or yield of milk components was not affected by diet, and averaged 3.53% fat, 3.11% protein, 1.55 kg/d fat, and 1.36 kg/d protein. Total tract digestibility of DM and OM increased from 71.4 to 73.0% and 72.4 to 76.1% for DM and OM, respectively, when level of RFC was increased. Total tract digestibility of fiber was unaffected by diet, but total tract starch digestibility increased from 93.1 to 97.4% when HMC replaced DC. Total urinary excretion of the purine derivatives uric acid and allantoin increased from 415 to 472 mmol/d when level of RFC was increased, and calculated microbial N supply increased from 315 to 365 g/d. When expressed as per kilogram of digestible OMI, increasing level of RFC tended to increase microbial N supply (20.4 vs. 22.2 g/kg). Cow productivity was not affected by forage particle size and ruminally fermentable carbohydrates in this study.

Allantoin↗
PubMed2003

Forage feeding to reduce preharvest Escherichia coli populations in cattle, a review.

Although Escherichia coli are commensal organisms that reside within the host gut, some pathogenic strains of E. coli can cause hemorrhagic colitis in humans. The most notable enterohemorrhagic E. coli (EHEC) strain is O157:H7. Cattle are asymptomatic natural reservoirs of E. coli O157:H7, and it has been reported that as many as 30% of all cattle are carriers of this pathogen, and in some circumstances this can be as high as 80%. Feedlot and high-producing dairy cattle are fed large grain rations in order to increase feed efficiency. When cattle are fed large grain rations, some starch escapes ruminal microbial degradation and passes to the hind-gut where it is fermented. EHEC are capable of fermenting sugars released from starch breakdown in the colon, and populations of E. coli have been shown to be higher in grain fed cattle, and this has been correlated with E. coli O157:H7 shedding in barley fed cattle. When cattle were abruptly switched from a high grain (corn) diet to a forage diet, generic E. coli populations declined 1000-fold within 5 d, and the ability of the fecal generic E. coli population to survive an acid shock similar to the human gastric stomach decreased. Other researchers have shown that a switch from grain to hay caused a smaller decrease in E. coli populations, but did not observe the same effect on gastric shock survivability. In a study that used cattle naturally infected with E. coli O157:H7, fewer cattle shed E. coli O157:H7 when switched from a feedlot ration to a forage-based diet compared with cattle continuously fed a feedlot ration. Results indicate that switching cattle from grain to forage could potentially reduce EHEC populations in cattle prior to slaughter; however the economic impact of this needs to be examined.

Animal Feed↗
PubMed2003

Effect of linseed oil supplementation on ruminal digestion in dairy cows fed diets with different forage:concentrate ratios.

The effect of linseed oil (LSO) supplementation on total-tract and ruminal nutrient digestibility, N metabolism, and ruminal fluid characteristics was investigated in dairy cows fed diets containing different forage to concentrate ratios (F:C). The experimental design was a 4 x 4 Latin square with 2 x 2 factorial arrangement of treatments. Four lactating Holstein cows were fed a forage-rich diet without LSO (F; F:C = 65:35, dry matter basis), a forage-rich diet with LSO (FO; F:C = 65:32, 3% LSO), a concentrate-rich diet without LSO (C; F:C = 35:65), or a concentrate-rich diet with LSO (CO; F:C = 35:62, 3% LSO). Total-tract digestibility of DM and OM was greater with supplemental LSO. A tendency for greater total-tract digestibility of NDF and ADF also was observed in cows fed LSO. Ruminal digestibility of NDF or ADF decreased when CO was fed compared with C. In contrast, feeding FO increased NDF or ADF digestibility compared with F. Although ruminal starch digestion was nearly complete with all diets, digestibility was greater when cows were fed C or CO compared with F or FO. Bacterial N flow to the duodenum decreased when FO was fed compared with F. In contrast, feeding CO increased bacterial-N flow compared with C. Neither F:C nor LSO supplementation affected ruminal pH or total VFA concentration in ruminal fluid. However, molar proportion of propionate was greater with C or CO compared with F or FO and increased with LSO supplementation regardless of F:C. Molar proportion of n-butyrate decreased with LSO supplementation. Total protozoal numbers in ruminal fluid decreased markedly only when CO was fed. Overall, data show that feeding LSO had no negative effects on total-tract digestion in dairy cows but may decrease ruminal fiber digestibility when fed with high-concentrate diets. The widely spread idea that LSO decreases digestibility, arising from studies with sheep, did not seem to apply to lactating cows fed 3% LSO.

Animals↗
PubMed2004

The effects of forage provision and group size on the behavior of calves.

The effects of providing alternative forages to individual or group-reared calves on their behavior were examined in 2 experiments. In experiment 1, 24 calves were reared in groups of 3 or individually in straw-bedded pens from age 1 to 7 wk. One-half of the calves in each treatment were provided with ad libitum cut perennial ryegrass herbage. Grass intakes and time spent eating grass were greater for grouped calves than for individual calves. Providing grass reduced concentrate intake of grouped calves and reduced the time that all calves, but particularly individual calves, spent eating straw bedding. Ruminating time was increased by offering grass to grouped calves compared with individual calves. Grass reduced the frequency of calves licking their buckets and their pen, vocalizing, and investigating their pen. Particularly for grouped calves provision of grass reduced all grooming. Group rearing reduced the frequency of calves licking their bucket, vocalizing, and investigating their pen, but had no effect on the frequency of pen licking. Calves were weaned at wk 7 and transferred to indoor silage feeding or grazing. Most effects of group rearing and grass provision were not maintained after weaning, but calves that had received grass ate for longer periods when turned out to pasture. In experiment 2, 72 calves were offered a mixture of straw, molasses, and pot ale syrup or grass hay. Calves offered the straw mixture ate more forage and concentrates and grew faster than calves offered hay. It was concluded that nontraditional forages, such as fresh grass and straw mixtures, could benefit the behavior and growth of calves compared with hay and straw.

Animal Feed↗
PubMed1986

Prepartum grain feeding and subsequent lactation forage program effects on performance of dairy cows in early lactation.

One hundred fifty-six Holstein cows were balanced prior to drying off to one of three diets offered during the dry period (dry matter basis): A) forage only (50% corn silage:50% alfalfa silage), B) forage as A plus a standard dairy grain mix (1.73% calcium), and C) same as B except a low calcium grain mix (.35% calcium). Grain feeding started 3 wk prepartum. Cows from each dry treatment were assigned to one of two treatments during the first 21 d postpartum: total mixed ration (dry matter basis); 50% grain:50% corn silage; or 50% grain:25% corn silage:25% alfalfa silage. Dry period feeding program had no effect on postpartum dry matter intake, milk yield, or composition. Prepartum grain feeding resulted in increased body weight gain during the last 3 wk of the dry period. Feeding corn silage postpartum as the sole forage resulted in higher dry matter intakes (15.0 vs. 14.1 kg/d), milk production (31.3 vs. 29.7 kg/d), and less body weight loss (36 vs. 58 kg) during the first 21 d postpartum than feeding a 50% corn silage:50% alfalfa silage mixture. However, differences varied depending on dry cow feeding program. All dry cow treatments resulted in a high incidence of milk fever (11.5, 11.5, and 15.5% for A, B, and C, respectively). Dry cow rations containing as little as 50% alfalfa silage appear to predispose cows to increased incidence of milk fever.

Animal Feed↗
PubMed1988

Impact of forage fiber content on digestion and digesta passage in lactating dairy cows.

Five Holstein cows (5 wk postpartum) were used in a Latin square design (15-d periods) to determine rumen fill and fractional rates of ruminal digestion and passage. Treatments consisted of prebloom, midbloom, and full bloom alfalfa hay, mature bromegrass hay, and corn silage fed in diets containing forage: concentrate in a 60:40 ratio (DM basis) formulated to be isonitrogenous. Intake of DM averaged 4.0% of body weight for prebloom alfalfa and corn silage. Milk yield and DM intake were lower for full bloom alfalfa and bromegrass than for prebloom alfalfa. Digestibility of organic matter was 7.5 percentage units lower for full bloom than for prebloom alfalfa. Weight of DM in the rumen was higher for midbloom and full bloom alfalfa and bromegrass than with prebloom alfalfa. Ruminal retention time of Yb applied to forage was longer for bromegrass than for prebloom alfalfa. Fractional rates of in situ NDF digestion were slower for full bloom alfalfa and bromegrass than for prebloom alfalfa. Results suggest that the point of limitation of feed intake due to gut fill is dependent on forage quality as well as energy demand of the animal. Dry matter fill of the rumen was more closely related to rates of ruminal digestion and passage than to total tract digestibility or maximum digestibility after lengthy in situ fermentation.

Animal Feed↗
PubMed1989

Effect of inoculation rate of selected strains of lactic acid bacteria on fermentation and in vitro digestibility of grass-legume forage.

Grass-legume forage was used to evaluate the effect of inoculation rate of selected strains of lactic acid bacteria on fermentation and in vitro digestibility during 57 d of ensiling. Chopped forage (DM = 28%) was ensiled in 4 to 6-kg quantities and treated as: 1) control, 10(3) epiphytic lactic acid bacteria; 2) 10(5) added lactic acid bacteria; and 3) 10(6) added lactic bacteria/g of wet forage. Samples were obtained for analyses on d 0, 1, 2, 3, 6, 10, 14, 29, and 57 of fermentation. Treated silages were observed to have: 1) greater quantities of lactic acid bacteria, 2) a greater proportion of homofermentative lactic acid bacteria, and 3) lactic acid bacteria with greater biological activity. Addition of each amount of lactic acid bacteria: 1) increased the rate of utilization of water-soluble carbohydrate and decline in pH, 2) limited the formation of NH3 N, and 3) increased the in vitro digestibility of DM and ADF. No differences were observed in the lactic acid content of the silages after 57 d of fermentation.

Ammonia↗
PubMed1990

Responses of lactating dairy cows to protected fats or whole cottonseed in low or high forage diets.

Thirteen treatments to compare effects of dietary fat on milk yield and composition were control, 15% whole cottonseed, and 2 and 4% Ca-tallowate factorially distributed in low forage (35% corn silage DM) with 14 or 18% CP and high forage (66% corn silage) diets with an additional diet of 8% Ca-tallowate. Different treatments were fed to 36 cows in each of three 28-d periods. Feeding 2 and 4% Ca-tallowate improved milk yield with high forage, although DM intake was slightly depressed; compared with 4% Ca-tallowate, DM intake and milk yield were depressed by 8% Ca-tallowate. Across all diets, whole cottonseed depressed DM intake and milk yield more than when nearly equal fat came from Ca-tallowate (4%). Calcium-tallowate depressed milk fat percentage linearly. Milk fat from cows fed whole cottonseed or Ca-tallowate contained unsaturated fatty acids (mostly C18:1) and lesser quantities of short-chain fatty acids. In a subsequent experiment, Ca-tallowate depressed milk fat percentage, whereas Megalac (calcium salts of fatty acids from palm oil) did not. In a field study, one trial with 210 cows in midlactation showed no effect on milk yield and composition from .54 kg of Megalac/d for 60 d, nor was there any effect detected with 121 cows in early lactation from feeding of .45 kg of Megalac/d for 90 d.

Animal Feed↗
PubMed1991

Detergent fiber traits to predict productive energy of forages fed free choice to nonlactating dairy cattle.

Hay crops that were predominantly alfalfa, clover or grass, and silage corn were harvested at early and late maturities to give a wide range in fiber contents. Hay crops were stored as field-cured hay and wilted silage. Each was fed for ad libitum intake to three or more nonlactating Holstein animals using total collection digestibility and calorimetry to measure DM intake, TDN, digestible energy, and metabolizable energy. Various fiber components (ADF, NDF, lignin), and expressions computed from them, were used to estimate TDN and digestible energy of forages or groups of forages having homogenous relationships. Stepwise backward elimination procedure was employed to discard independent variables or their squared terms at 5% probability to develop significant, biologically sound, practical predictive relationships. Standard NRC equations were used to extend energy densities to NEL. Free choice DM intake of forages (fed alone) was not closely related to NDF percentages. Estimates of NEL generally were higher when computed via TDN as opposed to digestible energy or metabolizable energy, which did not differ. We present equations to predict NEL from ADF via digestible energy for legumes, grasses, and corn silage, which differ markedly, in some cases, from those in current use. Equations for grasses had low r2, but these could not be compared with published ones, which apparently are based on treatment means rather than individual-animal observations. The NEL of hay crops and corn silages also were predicted from an expression of lignified NDF in DM with moderate precision.

Animal Feed↗
PubMed1996

Forage source alters nutrient supply to the intestine without influencing milk yield.

Eight Holstein cows in early lactation and fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design experiment to determine the influence of forage source on microbial digestion in the rumen and nutrient supply to the intestine and to determine relationships between DMI, ruminal fill, and NDF content of silage. Cows were fed a TMR formulated to contain a 50:50 concentrate:forage ratio. A significant negative correlation was found between dietary NDF concentration (range 32.2 to 37.9%) and DMI (16.7 to 19.6 kg/d). In addition to forage NDF concentration, the lower DMI of cows fed oat or triticale silage (16.7 and 17.2 kg/d, respectively) relative to that of cows fed barley or alfalfa silage (18.6 and 19.6 kg/d, respectively) might reflect a lower true rate of NDF digestion (range 2.39 to 4.09%/h), higher ruminal turnover time (12.9 to 17.1 h), and lower rate of NDF intake (3.31 to 3.96%/h). However, differences in ruminal bacterial yield, ruminal metabolites, and nutrient supply to the intestine associated with different silages had no major effect on dairy cow performance. We concluded that the dairy cow can maintain similar milk yield despite marked differences in the type of end products arising from carbohydrate and protein digestion.

Animal Feed↗