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PubMed2001

Metabolic rate and thermal stability during honeybee foraging at different reward rates.

During honeybee foraging, the stabilization of thoracic temperature (Tth) at elevated values is necessary to meet the power requirements of flight at different air temperatures (T(a)). To understand how the bee achieves thermal stability at different reward rates, the metabolic rates of undisturbed foraging bees were measured at different T(a) values and different sucrose solution flow rates. Metabolic heat production, calculated from the rate of carbon dioxide production, decreased linearly from 49.7 to 23.4 mW as T(a) increased from 19 to 29 degrees C (sucrose flow rate 1.75 microl x min(-1), 50 % w/w). In contrast, crop load and inspection rate remained constant. Metabolic rate displayed a linear relationship with both T(a) and the logarithm of the flow rate of sucrose solution (range analyzed 0.44-13.1 microl x min(-1), 50 % w/w). Metabolic rate decreased by 3.13+/-0.52 mW (mean +/- s.e.m., N=37) for every 1 degrees C increase in T(a) and increased by 4.36+/-1.13 mW for a doubling in flow rate. These changes in metabolic power output might be used to achieve thermal stability during foraging. It is suggested that the foraging bee might increase its Tth in accordance with the reward rate.

Animals↗
PubMed2004

The genetic architecture of the behavioral ontogeny of foraging in honeybee workers.

The initiation of foraging during the life course of honeybee workers is of central interest to understanding the division of labor in social insects, a central theme in sociobiology and behavioral research. It also provides one of the most complex phenotypic traits in biological systems because of the interaction of various external, social, and individual factors. This study reports on a comprehensive investigation of the genetic architecture of the age of foraging initiation in honeybees. It comprises an estimation of genetic variation, the study of candidate loci, and two complementary quantitative trait loci (QTL) maps using two selected, continually bred lines of honeybees. We conclude that considerable genetic variation exists between the selected lines for this central life history component. The study reveals direct pleiotropic and epistatic effects of candidate loci (including previously identified QTL for foraging behavior). Furthermore, two maps of the honeybee genome were constructed from over 400 AFLP markers. Both maps confirm the extraordinary recombinational size of the honeybee genome. On the basis of these maps, we report four new significant QTL and two more suggestive QTL that influence the initiation of foraging.

Aging↗
PubMed2002

Hazards of insecticides to the bumble bees Bombus impatiens (Hymenoptera: Apidae) foraging on flowering white clover in turf.

Insecticides used on turf are sometimes applied to areas with flowering weeds that attract honey bees and native pollinators. We tested residual effects of such treatments on colony vitality and behavior of the bumble bees Bombus impatiens Cresson foraging on turf containingwhite clover, Trifolium repens L. Imidacloprid, a syst emic chloronicotinyl used for preventive control of root-feeding grubs, was applied as granules, followed by irrigation, or sprayed as a wettable powder, with or without irrigation. Hives were confined on the plots in large field cages after residues had dried and colony vitality (i.e., numbers of brood, workers, and honey pots, and weights of queens, workers, and whole colonies with hives) was evaluated after 28-30 d. Workers' foraging activity and defensive response to an aggressive stimulus also were evaluated. In another test, weedy turf was sprayed with chlorpyrifos, carbaryl, or cyfluthrin at labeled rates for surface-feeding pests. Bee colonies were confined on the plots after residues had dried, with effects on colony vitality evaluated after 14 d. Finally, foraging activity of wild bumble bees was monitored on open plots to determine if insecticide-treated areas were avoided. Imidacloprid granules, and imidacloprid sprays applied with posttreatment irrigation, had no effect on colony vitality or workers' behavior, suggesting that such treatments pose little systemic or residual hazard to bumble bees. In contrast, exposure to dry nonirrigated residues of all of the aforementioned insecticides had severe impact on colony vitality. Foraging workers did not avoid insecticide-treated areas. Means by which turf managers can reduce hazards of insecticide applications to pollinators are discussed.

Agriculture↗
PubMedDate not supplied

Nitrogen availability from composts for humid region perennial grass and legume-grass forage production.

Perennial forages may be ideally suited for fertilization with slow N release amendments such as composts, but difficulties in predicting N supply from composts have limited their routine use in forage production. A field study was conducted to compare the yield and protein content of a binary legume-grass forage mixture and a grass monocrop cut twice annually, when fertilized with diverse composts. In all three years from 1998-2000, timothy (Phleum pratense L.)-red clover (Trifolium pratense L.) and timothy swards were fertilized with ammonium nitrate (AN) at up to 150 and 300 kg N ha(-1) yr(-1), respectively. Organic amendments, applied at up to 600 kg N ha(-1) yr(-1) in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC), or sewage sludge (SSLC), plus liquid dairy manure (DM). Treatments DM at 150 kg N ha(-1) yr(-1) and CSC at 600 kg N ha(-1) yr(-1) produced cumulative timothy yields matching those obtained for inorganic fertilizer. Apparent nitrogen recovery (ANR) ranged from 0.65% (SSLC) to 15.1% (DMC) for composts, compared with 29.4% (DM) and 36.5% (AN). The legume component (approximately 30%) of the binary mixture acted as an effective "N buffer" maintaining forage yield and protein content consistently higher, and within a narrower range, across all treatments. Integrating compost utilization into livestock systems that use legume-grass mixtures may reduce the risk of large excesses or deficits of N, moderate against potential losses in crop yield and quality, and by accommodating lower application rates of composts, reduce soil P and K accumulation.

Animal Feed↗
PubMed2000

Olfactory foraging by Antarctic procellariiform seabirds: life at high Reynolds numbers.

Antarctic procellariiform seabirds forage over vast stretches of open ocean in search of patchily distributed prey resources. These seabirds are unique in that most species have anatomically well-developed olfactory systems and are thought to have an excellent sense of smell. Results from controlled experiments performed at sea near South Georgia Island in the South Atlantic indicate that different species of procellariiforms are sensitive to a variety of scented compounds associated with their primary prey. These include krill-related odors (pyrazines and trimethylamine) as well as odors more closely associated with phytoplankton (dimethyl sulfide, DMS). Data collected in the context of global climatic regulation suggest that at least one of these odors (DMS) tends to be associated with predictable bathymetry, including upwelling zones and seamounts. Such odor features are not ephemeral but can be present for days or weeks. I suggest that procellariiforms foraging over vast distances may be able to recognize these features reflected in the olfactory landscape over the ocean. On the large scale, such features may aid seabirds in navigation or in locating profitable foraging grounds. Once in a profitable foraging area, procellariiforms may use olfactory cues on a small scale to assist them in locating prey patches.

Animals↗
PubMed1990

Influence of dietary forage and feed intake on carbohydrase activities and small intestinal morphology of calves.

Twenty (12 Holstein, 8 Longhorn cross) calves (198 kg and 7 mo old) were used in a randomized complete block design to evaluate the effects of dietary forage concentration and feed intake on carbohydrase activities and small intestinal (SI) morphology. Calves were individually fed 90% forage (alfalfa) or a 90% concentrate (50% sorghum: 50% wheat) diet at either one or two times NEm for 140 d and slaughtered; tissues and small intestinal digesta were collected. Increased feed intake increased (P less than .05) pancreatic weight, alpha-amylase and glucoamylase activities in the pancreas, SI length and SI digesta weight. Forage-fed calves gained faster (P less than .01) and had greater (P less than .05) pancreatic protein concentrations, alpha-amylase and glucoamylase activities in the pancreas and greater SI digesta alpha-amylase activities than grain-fed calves did. Increased feed intake increased (P less than .01) mucosal weight/cm small intestine only in forage-fed calves and increased (P less than .05) SI surface/volume only in grain-fed calves. Mucosal weight was greatest (P less than .05) at the terminal ileum, surface/volume was greatest (P less than .05) in the duodenum, and mucosal protein concentration was highest (P less than .05) in the SI mid-section. Mucosal lactase was higher (P less than .05) in proximal segments, whereas mucosal isomaltase was higher in middle and distal segments of the small intestine. For mucosal maltase activity, there was a feed intake x SI sampling site interaction (P less than .05) and for trehalase, a diet x feed intake x SI sampling site interaction (P less than .05). The SI distribution patterns of maltase and isomaltase were similar, as were those of trehalase and lactase. The alpha-amylase activity in the pancreas and SI morphology were influenced greatly by diet composition and feed intake by calves.

Amylases↗
PubMed1991

Influence of dietary forage and energy intake on metabolism and acyl-CoA synthetase activity in bovine ruminal epithelial tissue.

Twenty calves (7 mo old) were blocked by breed, sex, and weight into five groups of four calves and randomly assigned to either a 90% forage (alfalfa) or a 90% grain (50% sorghum and 50% wheat) diet fed at one (1M) or two (2M) times NEm for 140 d. Samples of ruminal epithelial tissue were collected from the anterior ventral sac, and papillae were cut free by hand and used for in vitro incubations and acyl-CoA synthetase assays. Substrates were acetate (90 mM), propionate (60 mM), butyrate (30 mM), and glucose (20 mM). Net productions of beta-hydroxybutyrate and acetoacetate from acetate were greater (P less than .01) with the 2M feeding; however, 14CO2 production from acetate was greater (P less than .05) with the grain diet. Net production of lactate (P = .09) and pyruvate (P less than .01) from propionate increased with the 2M feeding, whereas net lactate production from glucose decreased (P less than .01). Uptakes of VFA were similar with 1M and 2M feeding and were about 10-fold greater than uptakes of glucose. Production of 14CO2 from propionate was two- to fivefold greater than from acetate, butyrate, or glucose. Oxygen consumption was greater (P less than .01) with 2M feeding and unaffected by substrate. Activities of butyryl-CoA synthetase (nmol.mg of tissue-1.h-1) were greater (P less than .05) for animals consuming the forage diets. Addition of butyrate inhibited acetyl- and propionyl-CoA synthetase activity by 63 and 92%, respectively for all dietary treatments. Overall, metabolism of ruminal epithelial tissue tended to increase with the 2M feeding. Influence of dietary forage content on metabolism and activity of acyl-CoA synthetases was minimal, but the high-forage diet caused slight increases.

Animal Feed↗
PubMed1991

Influence of source and level of ruminal-escape lipid in supplements on forage intake, digestibility, digesta flow, and fermentation characteristics in beef cattle.

Six ruminally fistulated steers (550 kg) and 24 heifers (315 kg) were used to determine the effect of source and amount of ruminal-escape lipid in a supplement on forage intake and digestion. Steers were used in a 6 x 6 Latin square digestion study to evaluate six supplementation treatments: 1) negative control (NC), no supplement; 2) positive control (PC), soybean meal:grain sorghum supplement; 3) low-Megalac (calcium salts of fatty acids; LM) supplement; 4) high-Megalac (HM) supplement; 5) low-Alifet (crystallized natural animal fat, LA) supplement; and 6) high-Alifet (HA) supplement. Supplements were fed at .30% of BW on a DM basis and were isoenergetic within fat levels (high vs low). Steers were fed mature brome hay (7.2% CP) at 1.5% of BW on a DM basis. In the forage intake trial, heifers were assigned randomly to the same supplement treatments. Prairie hay (4.4% CP) was offered at 130% of ad libitum intake. Dry matter and NDF digestibility, ruminal DM fill, indigestible ADF passage rate, and fluid dilution and flow rates were not different (P greater than .10) among treatments. Total VFA concentrations were greater (P less than .01) and acetate-to-propionate ratio (Ac:Pr) was less (P less than .01) in supplemented groups; however, neither source nor level of escape lipid influenced either total VFA or Ac:Pr. Forage intake was greater (P less than .01) for supplemented groups than for the NC. At the high level of fat inclusion, heifers supplemented with Alifet ate slightly more (P less than .05) forage than those supplemented with Megalac.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effects of the inclusion of yeast culture (Saccharomyces cerevisiae plus growth medium) in the diet of dairy cows on milk yield and forage degradation and fermentation patterns in the rumen of steers.

The effects of including yeast culture (YC; Saccharomyces cerevisae plus growth medium; 5 x 10(9) organisms/g) in diets for ruminants was examined in two experiments. In Exp. 1, 32 multiparous Friesian dairy cows were fed between wk 7 to 12 of lactation one of four completely mixed diets based on either hay or straw plus rolled barley (mixed to give concentrate:forage ratios of either 50:50 or 60:40, respectively) with or without 10 g YC/d in a 2(3) factorial design. Supplementation with YC increased DM intake of the cows by a mean of 1.2 kg/d (P less than or equal to .062) and increased milk yield by 1.4 liters/d (corrected to 4% butterfat; P less than or equal to .05). There was an interaction (P less than .05) between diet composition and YC addition; effects of YC were greatest in diets containing 60:40 (concentrate:forage) ratio. In Exp. 2, three steers were fed a diet of 50% hay and 50% rolled barley (DM basis). Hay was available for the major part of the day but barley was fed in two meals/d. Addition of YC to the diet increased (P less than .05) ruminal pH for 4 h after the barley meal. This elevation in pH probably was due to a reduction (P less than or equal to .01) in the concentration of L-lactate in the ruminal liquor of steers given YC (1.43 vs 3.55 mM; P less than or equal to .01). Peak ruminal L-lactate concentration (7.75 mM) in the controls coincided with time of minimum pH values (2 h after the meal of barley); this peak was absent in steers given YC. YC had no effect on the concentration of VFA in ruminal liquor, but the ratio of acetate to propionate was reduced (P less than or equal to .01) from 3.3:1 to 2.8:1 in steers given YC. The extent of DM degradation of hay incubated in the rumen of steers fed the hay and rolled barley diet was increased (P less than .05) in the presence of YC at 12 h of incubation, but degradation was similar in all treatment groups after 24 h of incubation. Presence of yeast culture in the rumen had effects on ruminal stoichiometry. An increased rate of forage degradation may have increased forage intake and productivity of these dairy cows.

Animal Feed↗
PubMed1991

Pregnancy and lactation in beef heifers grazing tallgrass prairie in the winter: influence on intake, forage utilization, and grazing behavior.

Six ruminally and eight bifistulated (ruminal and esophageal) Hereford x Angus heifers were used to determine effects of pregnancy and early lactation on forage intake and utilization under grazing conditions. Three ruminally and three bifistulated heifers were bred (pregnant/lactating; P/L; average calving date was February 11, 1989); remaining heifers served as controls (C). The experiment consisted of three periods (P1 = average of 55 d before parturition; P2 = average of 12 d before parturition; P3 = average of 26 d after parturition). All heifers grazed the same 24-ha Flint Hills range pasture. Dehydrated alfalfa pellets were supplemented at .5% BW/heifer daily prepartum and at .8% BW/heifer daily postpartum. Treatment x period interactions were noted (P less than .10) for forage OM intake, ruminal capacity, indigestible ADF (IADF) fill, and grazing time but not for OM digestibility or IADF passage rate (P greater than .10). In P1 and P3, P/L heifers had greater (P less than .10) forage OM intake than C heifers, whereas no differences were noted (P greater than .10) in P2. Pregnant/lactating heifers spent less time (P less than .10) grazing than did controls in P2 and more time (P less than .10) than controls in P3. Ruminal IADF fill and ruminal capacity, as measured by water fill, tended (P = .14 and .16, respectively) to differ between the two groups in P2. Digestibility of OM was unaffected (P greater than .10) by physiological status, whereas IADF passage rate was greater (P less than .10) in P/L heifers. Only minor differences were noted for the chemical composition of diets selected by the two groups. Ruminal fermentation patterns shifted only slightly; the largest effects were in P3, when P/L heifers had greater (P less than .10) propionate and less (P less than .10) acetate (mol/100 mol) than C heifers. In summary, during the period just before parturition, differences in forage OM intake between P/L and C heifers disappeared, and ruminal fill and capacity tended to be lower for P/L heifers. Intake was 16% greater for P/L than for C heifers during the early postpartum period. Organic matter digestibility was not influenced by physiological status, even though IADF passage rates were greater for P/L heifers.

Animals↗
PubMed1992

Meat composition and palatability of Holstein and beef steers as influenced by forage type and protein source.

This experiment determined meat composition and palatability changes resulting from feeding Holstein (HOL) and crossbred beef (XB) steers diets containing corn silage (CS) or alfalfa haylage (AH) (forage type) and soybean meal (SM) or fish meal (FM) (protein source). Fifty-nine steers (30 HOL and 29 XB) were randomly assigned to diet combinations for a 2 x 2 x 2 (breed x forage x protein) factorial arrangement. Steers were fed to a fat-constant end point (fat depth over the longissimus muscle measured by ultrasound: 1.0 cm XB, .6 cm HOL). Proximate and fatty acid analysis and sensory evaluation were conducted on a rib eye roast and steaks, respectively, removed from the left side of each carcass at ribs 9 to 12. Proximate analysis of the longissimus muscle showed no significant difference (P greater than .05) in moisture, protein, or fat content due to breed, forage, or protein treatment. Forage type had no significant effect (P greater than .05) on amount of individual fatty acids found in longissimus muscle. However, total polyunsaturated fatty acids were higher (P greater than .05) for AH than for CS-fed animals. Longissimus muscle from steers fed FM had higher palmitoleic and lower stearic acid contents (both P less than .05) than longissimus muscle from animals fed SM. Muscle from HOL had higher palmitoleic and lower stearic acid contents than that from XB steers (both P less than .05). There was no significant interaction (P greater than .05) of breed with either diet treatment for individual fatty acid contents.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Effects of increasing levels of corn or beet pulp on utilization of low-quality crested wheatgrass hay by lambs and in vitro dry matter disappearance of forages.

Two trials were conducted to evaluate the effects of corn or dried beet pulp on intake and digestibility of forage by lambs and on IVDMD. In Trial 1, 16 lambs (average BW = 41 +/- .9 kg) were used in a randomized complete block design with eight lambs per block. Lambs were fed a crested wheatgrass hay (7.5% CP) and received either no supplement (NS), a protein supplement (PS), or protein supplements with various levels of corn or beet pulp. Corn supplements supplied 1.75 (PCL), 3.5 (PMC), and 5.25 (PHC) g of corn/kg of BW, whereas beet pulp supplements supplied 2.1 (PLBP), 4.2 (PMBP), and 6.3 (PHBP) g of beet pulp/kg of BW. All supplemented lambs received .128 g of CP/kg of BW. Hay DMI decreased linearly (P < .03) as the level of corn and beet pulp increased in the supplement. Total DMI decreased linearly (P = .013) as the level of corn increased; however, beet pulp did not affect total DMI (P > .71). Supplemental corn increased (P = .03) apparent diet DM digestibility (DMD), whereas supplemental beet pulp did not affect (P > .32) diet DMD. Lambs whose diet was supplemented with beet pulp had greater (P = .010) estimated hay DMD than lambs whose diet was supplemented with corn. In Trial 2, 48-h IVDMD was determined on each of three forages mixed with either corn or beet pulp. The crude protein content of the three forages was 4.9, 9.4, and 12.2% for low-, medium-, and high-quality forages, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Cow weights and reproduction on native rangeland and native rangeland-complementary forage systems.

Replicated cow herds of 15 Angus x Hereford (AH) and 15 Brahman x Hereford (BH) F1 cows each were placed on native rangeland (NR) or native rangeland-complementary forage (NRCF) systems. The NR was 8.1 ha of sagebrush-mixed prairie per cow-calf unit and the NRCF used the same mixed prairie complemented by .4 ha of double-cropped winter wheat and summer annual forage replacing about 30% of the mixed prairie for each cow unit. Calving seasons, spring for NR and fall for NRCF, were selected to complement the respective forage systems. Cow weights, reproductive performance, and population demographics were measured through seven calf crops to investigate their relationship to forage systems and cow breed types. Seasonal average cow weights increased from 484 +/- 7 (SE) kg during calf crop 1 to a peak weight of 568 +/- 8 kg at calf crop 5. Average weight of AH cows was 514 +/- 3 kg, compared with 539 +/- 3 kg for the BH cows (P < .01). Angus x Hereford and BH cows were 38 and 44 kg heavier, respectively, on the NRCF system than on the NR system. The average percentage of reproduction for AH cows was 90 +/- 2%, compared with 87 +/- 2% for the BH cows (P < .13). Both breeds had approximately 87 (AH) to 89% (BH) reproductive rate on the NR system. In contrast, AH cows had 94 +/- 2% reproduction on the NRCF system, compared with 84 +/- 2% for the BH cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1994

Forage level and particle size effects on orchardgrass digestion by steers: I. Site and extent of organic matter, nitrogen, and cell wall digestion.

Four steers (502 +/- 49 kg) with ruminal, duodenal, and ileal cannulas were used in a 4 x 4 Latin square experimental design with a 2 x 2 factorial arrangement of treatments to determine the effects of dietary forage:concentrate ratio (96:4 [96F] and 60:40 [60F]) and forage particle size (long hay [L] and coarsely ground hay [G]) on site and extent of digestion of OM, N, and plant cell wall monomeric components. Orchardgrass hay was the forage source used and was the sole source of cell wall material fed to steers (DMI = 88.6 g/kg BW.75). Diurnal variation in ruminal pH was greater when steers consumed 60F vs 96F (P < .01) and greater for G vs L (P < .10). Ruminal fluid volumes (liters) and daily outflows (liters/day) were greater (P < .05) when steers consumed 96F or L. True ruminal OM digestion (percentage of intake) was greater (P < .05) when steers consumed 60F (69.0) vs 96F (59.5) or L (65.8) vs G (62.7). Efficiency of net bacterial CP synthesis (grams of N/kilogram of true ruminal OM disappearance) was greater (P < .05) when steers consumed 60F (33.8) vs 96F (30.8). Total tract digestibilities of NDF and ADF were 63.3 and 53.0% when steers consumed 96F and were decreased (P < .05) to 52.3 and 43.8% when steers consumed 60F. Total tract digestibilities of plant cell wall arabinose, galactose, glucose, xylose, and uronic acids were 78.7, 69.7, 70.8, 67.6, and 79.7% when steers consumed 96F and were decreased (P < .05) when steers consumed 60F. Ruminal digestion accounted for greater than 90% of total tract digestion of all cell wall monosaccharide components when steers consumed 96F but accounted for 6 to 20 percentage units less of total digestion when steers consumed 60F. Total tract disappearances of cell wall acetyl groups, ferulic acid, and p-coumaric acid were 62.4, 79.4, and 50.6% when steers consumed 96F and were decreased (P < .05) to 49.7, 73.2, and 42.2% when steers consumed 60F. Addition of concentrate to diets, but not forage processing, decreased total tract digestibilities of cell wall components and shifted site of digestion to the lower gastrointestinal tract.

Animal Feed↗
PubMed1994

Evaluation of Brassicas in grazing systems for sheep: I. Quality of forage and animal performance.

Four years of grazing trials were conducted with Brassica forages to evaluate their chemical composition and effect on ADG of fattening lambs and breeding ewes in late fall. Brassicas tested included kales (Brassica oleracea L. var. acephala DC), turnips (B. rapa L.), and a chinese cabbage hybrid (B. rapa L. x B. pekinensis [Lour.] Rupr.). Daily gains of lambs varied widely among years (19 to 330 g/d); ADG on Brassicas were, however, generally higher than on stockpiled Kentucky 31 tall fescue (Festuca arundinacea Schreb.) or orchardgrass (Dactylis glomerata L.)-red clover (Trifolium pratense L.) pastures grazed at the same time. In 1 yr, dietary supplementation of lambs grazing a hybrid turnip (Forage Star) with iodine and copper oxide needles improved (P < .05) ADG; however, there was no effect on gains in two later years. In 2 yr, lambs showed higher ADG on Tyfon chinese cabbage hybrid (241 and 330 g/d) than on Forage Star turnip (197 and 275 g/d) or stockpiled grass-clover (135 and 233 g/d), but yield of Tyfon was lower. Indications that supplementary hay improved ADG of lambs and ewes were not confirmed in the final year, in which hay increased (P < .05) ADG of lambs in the first 3 wk of grazing Brassicas but decreased gains later. Thyroid weights were increased (P < .01) consistently in all trials on Brassicas, but enlargement was modest and not related to ADG. Brassica forages provided high yields (5.6 to 10.5 t/ha) of DM in the late fall to early winter period, with high carrying capacity for sheep but large variability in ADG.

Animal Feed↗
PubMed1995

Influence of processing supplemental alfalfa on intake and digestion of dormant bluestem-range forage by steers.

Four ruminally and duodenally fistulated, 2-yr-old Angus x Hereford steers (average initial BW = 370 kg) were used to evaluate the effect of method of processing supplemental alfalfa on intake and digestion of dormant bluestem-range forage (2.8% CP, 78% NDF). Treatments (4 x 4 Latin square) were 1) control, no supplement; 2) ground and pelleted alfalfa hay (PELLET; 21% CP, 37% NDF); 3) ground and pelleted dehydrated alfalfa (DEHY; 21% CP, 44% NDF); and 4) longstem alfalfa hay (HAY; 20% CP, 37% NDF). All supplements were from a single cutting of alfalfa and fed at .5% BW (as-fed basis). Supplementing steers with alfalfa increased (P < or = .07) bluestem forage OM intake (FOMI); total OM intake (TOMI); true ruminal OM digestibility; total tract OM digestibility (TTOMD); total N, microbial N, and nonammonia-nonmicrobial N (NANM) flows to the duodenum; ruminal OM and fluid fill; fluid dilution rates; dietary DE concentration; and ruminal total VFA and NH3 N concentrations. Because of the enhanced FOMI and TOMI associated with alfalfa supplementation and the concomitant improvement in TTOMD, digestible OM intake (DOMI) also increased (P < .01) when supplemental alfalfa was fed. Method of processing alfalfa had little impact on forage utilization, except FOMI (P = .11), TOMI (P = .10), and ruminal OM fill (P = .09) tended to be greater when supplemental alfalfa pellets were dehydrated. Similarly, processing method tended to alter the molar proportions of some minor VFA. In conclusion, alfalfa supplementation exerted a dramatic impact on utilization of low-quality forage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1995

Effects of forage level and canola seed supplementation on site and extent of digestion of organic matter, carbohydrates, and energy by steers.

The objective of this study was to determine the effects of fat supplementation from canola seed (CS) on ruminal fermentation and postruminal digestion of OM, carbohydrates, and energy of diets containing different levels of forage. Six ruminally and duodenally cannulated beef steers (354 kg +/- 18) were given ad libitum access to six isonitrogenous diets that were offered twice daily in a 6 x 6 Latin square design. Treatments were arranged as a 2 x 3 factorial with two forage levels (70 vs 30% of dietary DM as corn silage) and three forms of CS supplementation including no CS or CS added at 10% of dietary DM as whole CS treated with alkaline hydrogen peroxide or untreated crushed CS. Fat from CS provided 5% of dietary DM. The remaining dietary ingredients were corn, canola meal, molasses, and urea. No interactions (P > .05) between dietary forage level and CS supplementation were observed for ruminal characteristics or digestion of OM, carbohydrates, and energy in the rumen, postruminally, or in the total tract. Fat supplementation from CS did not affect (P > .05) DMI. With few exceptions, fat supplementation did not affect (P > .05) ruminal, postruminal, or total tract digestibilities of OM, structural and nonstructural carbohydrates, and GE. Ruminal disappearance of GE was decreased (P < .05) when diets were supplemented with fat from whole treated CS, and total tract digestibilities of OM and GE were decreased (P < .05) when diets were supplemented with fat from CS in either form. Ruminal pH, concentrations of NH3 N and total VFA, and molar proportions of acetate, propionate, and butyrate were not affected (P > .05) by fat supplementation. Results suggest that fat supplementation from CS (at 5% of dietary DM) as whole treated or untreated crushed had no negative effects on ruminal fermentation of OM, carbohydrates, or energy when steers were given ad libitum access to diets containing high or low forage.

Animal Feed↗
PubMed1995

Influence of forage level and naloxone injection on feed intake, digestion, and plasma hormone and metabolite concentrations in dairy heifers.

Four ruminally cannulated Holstein heifers (287 +/- 26 kg) in a 4 x 4 Latin square were used to evaluate the effects of naloxone injection and forage level on dietary intake, ruminal fermentation characteristics, digestibility, and plasma hormone and metabolite concentrations. Treatments were arranged in a 2 x 2 factorial with naloxone injection (0 vs .3 mg/kg; saline vs naloxone, respectively) and forage level (20 vs 100%; concentrate vs forage) as factors. Stanchioned heifers were allowed 21 d for adaptation before a 5-d collection period. Plasma samples were collected several times on d 1 and daily at 0730. Concentrate-fed heifers consumed more feed (P < .10) than forage-fed heifers. Naloxone injection decreased (P < .10) feed intake (grams/kilogram BW) at 1 and 2 h after feeding on d 1. On d 3 at 24 h after feeding, naloxone-injected heifers had increased DM (P < .10) intakes compared with control (saline-injected) heifers. Concentrate-fed heifers had decreased (P < .10) ruminal pH and increased total ruminal VFA concentration. Acetate proportion was decreased (P < .10) and propionate proportion increased in concentrate-fed heifers. Naloxone-injected heifers had decreased (P < .10) total VFA concentrations and increased propionate proportions. Concentrate-fed heifers had greater (P < .10) DM, OM, and CP digestibilities as well as increased plasma (P < .10) insulin, urea N, and glucose concentrations but decreased (P < .10) GH and NEFA concentrations. Naloxone injection increased (P < .10) plasma insulin concentration. Naloxone injection in dairy heifers reduces intake up to 2 h after injection, alters ruminal fermentation patterns, and increases plasma insulin concentration.

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