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PubMed2001

Effects of predator chemical cues and behavioral biorhythms on foraging activity of terrestrial salamanders.

Red-backed salamanders, Plethodon cinereus, show a variety of alarm responses to chemical cues from eastern garter snakes, Thamnophis sirtalis. We measured the foraging activity of red-backed salamanders exposed to water soiled by a garter snake (fed P. cinereus) or to unsoiled water. Salamanders exposed to snake-soiled water showed less foraging activity than salamanders exposed to unsoiled water; therefore, predators could have nonlethal effects on salamander populations. Our results also show additional factors influenced salamander foraging activity. Salamander foraging activity and responsiveness to chemical cues do not appear to have been affected by sex or food deprivation. Salamander foraging activity does appear to have been influenced by activity biorhythms. Foraging activity of animals in both treatments showed a bimodal periodicity that is consistent with natural activity patterns controlled by internal biorhythms. Exposure to snake-soiled water significantly reduced foraging activity during periods of peak foraging activity, but had a subtler effect on foraging activity during natural lulls in activity. We suggest that both activity biorhythms and exposure to chemical cues are important factors affecting salamander foraging behavior.

Animals↗
PubMed2001

Foraging behaviour in Drosophila larvae: mushroom body ablation.

Drosophila larvae and adults exhibit a naturally occurring genetically based behavioural polymorphism in locomotor activity while foraging. Larvae of the rover morph exhibit longer foraging trails than sitters and forage between food patches, while sitters have shorter foraging trails and forage within patches. This behaviour is influenced by levels of cGMP-dependent protein kinase (PGK) encoded by the foraging (for) gene. Rover larvae have higher expression levels and higher PGK activities than do sitters. Here we discuss the importance of the for gene for studies of the mechanistic and evolutionary significance of individual differences in behaviour. We also show how structure-function analysis can be used to investigate a role for mushroom bodies in larval behaviour both in the presence and in the absence of food. Hydroxyurea fed to newly hatched larvae prevents the development of all post-embryonically derived mushroom body (MB) neuropil. This method was used to ablate MBs in rover and sitter genetic variants of foraging to test whether these structures mediate expression of the foraging behavioural polymorphism. We found that locomotor activity levels during foraging of both the rover and sitter larval morphs were not significantly influenced by MB ablation. Alternative hypotheses that may explain how variation in foraging behaviour is generated are discussed.

Animals↗
PubMed1999

Flight speed and body mass of nectar-feeding bats (Glossophaginae) during foraging.

Aerodynamic theory predicts that minimum power (Vmp) and maximum range (Vmr) flight speeds increase when the body mass of an individual animal increases. To evaluate whether foraging bats regulate their flight speed within a fixed speed category relative to Vmp or Vmr, I investigated how the natural daily changes in body mass caused by feeding affected the flight speed of neotropical nectar-feeding bats (Phyllostomidae: Glossophaginae) within a strictly defined, stereotyped behavioural context. Individual bats were maintained in a flight tunnel (lengths of five different types 14-50 m) with a fully automated feeding, weighing (using an electronic balance at the roost) and flight speed measuring system. Flight speeds were measured during normal nocturnal foraging activity by an undisturbed bat while it flew between the two ends of the flight tunnel to obtain food from two computer-controlled nectar-feeders. For a comparison of flight enclosure measurements with field data, flight speeds were also obtained from unrestrained bats foraging in their natural environment (Costa Rica). Foraging flight speeds spanned a range of at least a factor 3 within a single species, which demonstrates the wide range of speeds possible to these animals. Significant, positive correlations between flight speed and the natural individual variability in body mass were found in nearly all cases, with body mass exponents ranging between 0.44 and 2.1. Bats flying at normal speeds were therefore not near their upper limit of muscle power. The most reliable measurements of speed increase with mass (with individual mass changes of up to 30%) were close to the increase theoretically predicted for Vmp and Vmr for an individual bat (with constant wing span and area), which should vary as M0.42, where M is mass. This provides evidence that the glossophagine bats attemped to maintain their flight speed within a fixed speed category relative to Vmp or Vmr during foraging. Among differently sized species of glossophagine bat (N=4), flight speeds V varied with V=20M0.23, in agreement with the mass exponent of 0.21 expected from aerodynamic models for interspecific variation. In addition to the mass effect, at least five other variables significantly influenced flight speed. (1) Both mean and maximum flight speeds increased with the length and the cross-sectional area of the flight tunnel. Mean (maximum) flight speeds of 11-12 g Glossophaga soricina bats (in m s-1) were 4.6 (5.3) over a 7 m and 7. 3 (10.5) over a 50 m flight path. (2) The flight speed range adopted by a bat during one night could vary significantly between nights, independently of body mass and the effect of the size of the flight enclosure. (3) Bats flew significantly faster under illumination than in darkness. This effect was shown (i) by bats kept under natural ambient illumination that initiated foraging during the twilight phase of the evening, (ii) when bats continued to feed into the light phase directly after the dark-light transition in the laboratory and (iii) during foraging under constant, artificial illumination. (4) After a period of rest, the initial flight speed during a foraging bout was significantly increased by 25%, but declined to the mean level within 20 s of activity. (5) Flight speed could differ significantly between foraging (flight from feeder to feeder) versus non-foraging (flight from end to end of the enclosure without visiting the feeders) flights. The results of this study demonstrate a clear ability of bats to regulate their flight speed in response to small natural changes in body mass as predicted by aerodynamic theory for Vmp and Vmr. The set point in flight speed regulation, however, was influenced by multiple additional variables.

Animals↗
PubMed1996

In situ particle size reduction as affected by forage species and grinding mesh size.

Two ruminally cannulated heifers were used to evaluate effects of three forage species (gamagrass, orchardgrass, and red clover) ground through two mesh sizes (2 and 5 mm) in a 3 x 2 factorial arrangement on particle size reduction in situ. Residues in polyester bags incubated for 3, 6, 12, 24, 36, 48, 60, and 72 h were analyzed for mean particle size. Initially, gamagrass had a 10.2% greater (P < .05) proportion of DM as particles larger than 300 microns that did orchardgrass or red clover, whereas forages ground through a 5-mm mesh (5-mm forage) had a 7.5% greater (P < .05) proportion of DM as 300 microns or larger particles than forages ground through a 2-mm mesh (2-mm forage). Mean particle size decreased with incubation time, resulting in reductions of 44, 42, 53, and 49% of gamagrass, orchardgrass, and 2- and 5-mm forages, respectively, after 60 h. Mean particle size of red clover was reduced 67% after 36 h of incubation. Particle size reduction was initiated earlier (12 vs 36 h) and occurred at a 150% faster (P < .01) rate for red clover than for gamagrass or orchardgrass. Although there was no difference (P > .10) between grinding mesh size at the time at which particle size reduction was initiated (24 h), particle reduction occurred at a 136% faster (P < .05) rate for forages ground through a 5-mm screen than for forages ground through a 2-mm screen. A greater (P < .10) reduction (595 microns by 36 h) in mean particle size occurred in red clover than in gamagrass or orchardgrass (average 376 microns by 60 h) during ruminal incubation. In addition, 5-mm forages exhibited a greater (P < .10) reduction in mean particle size (527 microns) than did 2-mm forages (372 microns) after 60 h of incubation. Substantial particle size reduction occurred in situ due to microbial digestion. The faster particle size reduction found in red clover may contribute to the greater observed intake for legumes.

Animal Feed↗
PubMed1999

Fractionation of fiber and crude protein in fresh forages during the spring growth.

The composition of the fiber and CP of alfalfa, bromegrass, and endophyte-free and -infected tall fescue forages was compared during the spring growth from vegetative to reproductive stages. Forages were sampled from April 27 to June 6 in 1994, and from April 27 to June 11 in 1995, with 11 and 12 harvest dates, respectively. Total dietary fiber (TDF) was fractionated into insoluble and soluble fiber (SF). The CP of the forages was fractionated into nonprotein N (A), soluble CP (B1), insoluble CP that was soluble in neutral detergent (B2), CP insoluble in neutral detergent but soluble in acid detergent (B3), and CP insoluble in acid detergent (C). Effects of year, forage species, and harvest dates (day as a covariable) were included in the model. Across harvest dates, alfalfa (A) had lower (P < .01) TDF and higher (P < .01) SF concentrations than grasses (GR) (A: 49.9 and 14.4% and GR: 60.4 and 4.5% [OM basis] for TDF and SF, respectively). Alfalfa had higher (P < .01) CP (20.6% DM) than GR (15.3%). The rate of decrease in CP (% DM) across days was higher (P < .01) for bromegrass (-.4%/d) than for the other forages (-.29%/d). Fraction A (% of CP) was not different (P = .24) among forages (22.5%), but B1 was higher (P < .01) in A (17.1%) than in GR (13.2%). The B2 fraction (% of CP) was higher (P < .01) in A compared with GR (51.6 vs 45.9%, respectively). Alfalfa had lower (P < .01) B3 (3.0% of CP) than bromegrass (18.6%) and tall fescue (13.2%). Fraction C was not different (P = .23) among forages (3.8%). Fractions A, B1, and C (% of CP) did not change (P > .05) across days for all forages. Fraction B2 (% of CP) decreased across days in A (-.21%/d) but was not affected in GR. Fraction B3 (% of CP) increased (P < .05) in A (.1%/d), decreased in endophyte-infected tall fescue (-.20%/d), and did not change (P > .05) in the other forages. Crude protein and fiber composition were affected more by forage species than by maturity. The CP and NDF concentrations were more affected by maturity. Insoluble fractions but not soluble fractions of CP were affected by maturity.

Animal Feed↗
PubMed2000

Effect of maturity on degradation kinetics of sod-seeded cereal grain forage grown in northern Arkansas.

Wheat (Triticum aestivum L.), oat (Avena sativa L.), and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested at 3-wk intervals throughout March, April, May, and early June. Plant growth stage was documented for each forage on each harvest date, and harvested forages were evaluated for forage quality characteristics. Degradation kinetics of DM and NDF for these forages were evaluated by the in situ method. Fractional degradation rates for DM and NDF in all three species were relatively rapid for vegetative forage (> or =0.086 h(-1)) but declined rapidly by the heading stage of development and stabilized thereafter. Forage quality declined and forages were more resistant to ruminal degradation as plants entered the reproductive stages of growth. Based on these findings, growth stage is an effective predictor of most characteristics of in situ DM and NDF disappearance. The relationships between these degradation parameters and growth stage were typically explained with quadratic or cubic models. Clearly, forage quality characteristics of overseeded rye deteriorated more rapidly with phenological development and growth stage than quality characteristics of overseeded wheat and oat grown in the same environment. For rye, this problem is further complicated by its accelerated phenological development. These factors combine to permit a very narrow harvest window in early spring, relative to the other cereal grains evaluated. Acceptable forage quality may persist for an extended period in wheat and oat; this suggests that producers wishing to utilize these forages may lengthen the harvest window by planting more than one species, either as a mixture or preferably in independent stands.

Animal Feed↗
PubMed2003

Managing manure nutrients through multi-crop forage production.

Concentrated sources of dairy manure represent significant water pollution potential. The southern United States may be more vulnerable to water quality problems than some other regions because of climate, typical farm size, and cropping practices. Dairy manure can be an effective source of plant nutrients and large quantities of nutrients can be recycled through forage production, especially when multi-cropping systems are utilized. Linking forage production with manure utilization is an environmentally sound approach for addressing both of these problems. Review of two triple-crop systems revealed greater N and P recoveries for a corn silage-bermudagrass hay-rye haylage system, whereas forage yields and quality were greater for a corn silage-corn silage-rye haylage system, when manure was applied at rates to supply N. Nutrient uptake was lower than application during the autumn-winter period, and bermudagrass utilized more of the remaining excess than a second crop of corn silage. Economic comparison of these systems suggests that the added value of the two corn silage crop system was not enough to off-set its increased production cost. Therefore, the system that included bermudagrass demonstrated both environmental and economic advantages. Review of the N and P uptake and calculated crop value of various single, double, and triple crop forage systems indicated that the per hectare economic value as well as the N and P uptakes tended to follow DM yields, and grasses tended to out-perform broadleaf forages. Taken across all systems, systems that included bermudagrass tended to have some of the highest economic values and uptakes of N and P. Manure applied at rates to supply N results in application of excess P, and production will not supply adequate quantities of forage to meet the herd's needs. Systems that lower manure application and supply supplemental N to produce all necessary forage under manure application will likely be less economically attractive due to additional costs of moving manure further and, applying it to greater land areas, but will be environmentally necessary in most cases. Intensive forage systems can produce acceptable to high quality forage, protect the environment, and be economically attractive. The optimal manure-forage system will depend on the farm characteristics and specific local conditions. Buffers and nutrient sinks can protect streams and water bodies from migrating nutrients and should be included as a part of crop production systems.

Agriculture↗
PubMed1999

Partial replacement of forage with nonforage fiber sources in lactating cow diets. I. Performance and health.

Seventy-eight Holsteins were fed for 112 d to evaluate performance and health responses to diets varying in source and concentration of fiber. Three diets based on different carbohydrate feeding strategies were formulated. These diets contained low concentrations of forage and neutral detergent fiber (NDF) (12.6% forage NDF, 19.5% total NDF), adequate NDF and forage (20% forage NDF, 24.8% total NDF), or low forage with additional NDF from cereal byproducts (12.7% forage NDF, 33.4% total NDF). Responses to sodium bicarbonate supplementation (0 or 0.8% of diet DM) were evaluated for each carbohydrate strategy, and bicarbonate improved performance on all diets. Eight cows were used concurrently in a Latin square experiment to evaluate the linearity of milk fat concentration response to increasing concentrations of byproduct NDF in low-forage diets. Considering both trials, cereal byproduct NDF was only 27% as effective as NDF from alfalfa silage in eliciting a milk fat concentration response, which was less than predicted from previous experiments. This difference was not because of the short duration of previous experiments nor because of nonlinearity in the response to byproduct NDF. Low-forage diets fed for 112 d did not result in major health disorders for midlactation cows. However, several indicators suggested that cows fed low-forage, high-NDF diets might be less susceptible to ruminal acidosis than those fed diets containing low forage and low NDF, especially during times of dietary transition. Although the effective fiber value in various feeds is variable and difficult to quantify, the value of byproduct fiber needs to be considered when balancing the carbohydrate fraction of dairy rations.

Acetates↗
PubMed2000

Perception of the pollen need by foragers in a honeybee colony.

Honeybees, Apis mellifera, adjust their pollen foraging activity according to the need for pollen within the colony, determined by the amount of stored pollen and young brood present in the hive. To clarify how pollen foragers detect the supply of pollen, we followed individual honeybees while they were returning with pollen. Pollen foragers deposited their loads on the frame where most of the unsealed brood was, independent of the position of this frame within the hive. They also inspected more cells on that frame and spent most of their time there, indicating that pollen foragers may individually evaluate the pollen requirements of the colony. In 18 normal-sized colonies we also tested whether olfactory cues provided by a frame of hungry young brood or an additional pollen frame covered by cages affect foraging activity. These experiments showed that olfactory stimulation within the colony is insufficient to increase or decrease the foraging effort, but suggest that foragers must have direct contact with the brood and pollen area to regulate their foraging activity according to the conditions in the colony. The different mechanisms by which foragers may gather the information about pollen supply are discussed. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2002

Assessment of food source profitability in honeybees (Apis mellifera): how does disturbance of foraging activity affect trophallactic behaviour?

When forager honeybees (Apis mellifera) return to the hive after a successful foraging trip, they unload the collected liquid to recipient hive mates through mouth-to-mouth contacts (trophallaxis). The speed at which the liquid is transferred (unloading rate) from donor to recipient is related to the profitability of the recently visited food source. Two main characteristics that define this profitability are the flow of solution delivered by the feeder and the time invested by the forager at the source (visit time). To investigate the effect of visit time on trophallactic behaviour, donor foragers were trained to a rate feeder that could deliver different flows of solution. We dissociated visit time and flow of solution by introducing pauses in the solution's deliverance at different moments of the foraging visit. We analysed whether timing of the non-deliverance period within the visit is important for the forager's assessment of resource profitability. During the subsequent trophallactic encounter with a hive mate, unloading rate was related to the total time invested by the forager at the food source only if the ingestion process had already been started. These results together with previous ones suggest that foragers integrate an overall flow rate of solution of the feeder throughout the entire foraging visit.

Animals↗
PubMed1998

The effect of genotype on response thresholds to sucrose and foraging behavior of honey bees (Apis mellifera L.).

Honey bee foragers were tested for their proboscis extension response (PER) to water and varying solutions of sucrose. Returning pollen and nectar foragers were collected at the entrance of a colony and were assayed in the laboratory. Pollen foragers had a significantly higher probability of responding to water and to lower concentrations of sucrose. Bees derived from artificially selected high- and low-pollen-hoarding strains were also tested using the proboscis extension assay. Returning foragers were captured and tested for PERs0 to 30% sucrose. Results demonstrated a genotypic effect on PERs of returnining foragers. The PERs of departing high- and low-strain foragers were consistent with those of returning foragers. The PERs were related to nectar and water reward perception of foragers. High strain bees were more likely to return with loads of water and lower concentrations of sucrose than foragers from low pollen strain. Low-strain bees were more likely to return empty. We identified a previously mapped genomic region that contains a variable quantitative trait locus that appears to influence sucrose response thresholds. These studies demonstrate a gene-brain-behavior pathway that can be altered as a consequence of colony-level selection for quantities of stored food.

Animals↗
PubMed2002

Soybean hulls, wheat middlings, and corn gluten feed as supplements for cattle on forage-based diets.

Soybean hulls, wheat midds, and corn gluten feed are viable alternative supplements for forage-fed cattle. All three result from the processing of major Unites States agricultural crops, so large supplies are available. Their value is better for ruminant animals than for monogastrics because they contain digestible fiber components. These byproducts are widely available throughout the Unites States and will generally be more economical than traditional feed grains or commercial feeds when used appropriately as supplements to forage-based diets. Knowledge about the composition of base forage must be used in planning supplementation strategies because base forages vary in protein and mineral content [9]. Soybean hulls alone may be a good selection in situations in which forages are adequate or high in protein. In situations where forage is marginal or deficient in protein, wheat midds, corn gluten feed, or a mix of soybean hulls and corn gluten feed might be most desirable. All three feeds can be variable in nutrient composition, so they should be analyzed to ensure a balanced nutrient level in diets. Soybean hulls are especially variable in crude protein content and should always be analyzed when forages are marginal or deficient in protein. Despite the fact that published energy levels are substantially lower, research has shown that soybean hulls and wheat midds have a value comparable to corn and soybean meal in forage-based diets. Corn gluten feed has also been comparable to corn and soybean meal in most reports but is closer in value to its published energy levels. In general, results with soybean hulls have been surprisingly good and consistent, whereas responses to wheat midds and corn gluten feed supplementation have been more variable and sometimes disappointing. Feeding rates for soybean hulls can range from low to extremely high depending on forage availability and desired performance. Wheat midds should be limited in most situations to 50% of the expected dry matter intake because of their rapidly digested starch content. Corn gluten feed should be limited to approximately 50% of expected dry matter intake because of its high sulfur content. Several research groups are currently evaluating self-feeding programs for these byproducts, and while the potential for health and production problems exist, results have been encouraging in most cases. Self-feeding would reduce the labor costs of hand feeding and could provide backgrounders with a program to expand cattle numbers on a limited land base.

Animal Feed↗
PubMed2003

Foraging mode and evolution of strike-induced chemosensory searching in lizards.

Strike-induced chemosensory searching (SICS) in lizards and snakes is a means of relocating prey by scent-trailing. The two main components of SICS are an elevated tongue-flick rate for vomerolfactory sampling after biting prey (PETF) and searching movements. In combination, these behaviors permit scent-trailing. Prey chemical discrimination, which is a prerequisite for SICS, is present in active foragers, but not in ambush foragers. Using comparative data. I show that searching movements and SICS have undergone correlated evolution with foraging mode and with prey chemical discrimination in lizards. This suggests that active foraging selects for prey chemical discrimination, which is then employed to search for escaped prey using the typical movements and tongue-flicking behaviors of active foragers. SICS in lizards is simply heightened active foraging after biting prey. In nonvenomous snakes, SICS is similar to that in lizards but is not restricted to active foragers. Only highly venomous snakes voluntarily release dangerous prey upon envenomation, pause to let the venom incapacitate the prey, and then relocate the prey by scent-trailing. PETF was observed in two ambush foragers and is not evolutionarily correlated with foraging mode or searching movements. Because it occurs in species lacking prey chemical discrimination, such PETF may be a response to gustatory cues or to internal chemicals not encountered on surfaces or trails of uninjured prey.

Adaptation, Physiological↗
PubMed2001

The role of gut tissue in the energy metabolism of growing lambs fed forage or concentrate diets.

The role of the gastrointestinal tract (GIT) in explaining the less efficient utilization of metabolizable energy (ME) in growing lambs fed forage rather than concentrate-based diets was investigated by feeding forage (legume-grass silage) and concentrate (whole shelled maize) diets, at isoenergetic intakes (ME basis), using five groups of lambs. One group of seven lambs was an initial slaughter group and of the two groups (eight lambs per group) fed each diet, one group was fed for 8 weeks, whereas the other group was fed for 16 weeks. All lambs were slaughtered between 18.5 and 20 h following their last meal. Retained energy (as a percentage of ME intake) was higher (concentrate-fed 28, forage-fed 17; P<0.001) for the concentrate-fed animals. Weight-specific mucosal O2 uptake (ml/g DM per h), measured in vitro, was 37 % higher for the forestomach (reticulum, rumen and omasum) and small intestine (jejunum) than for the abomasum and large intestine (caecum and colon), but there was no evidence for a diet effect (except colon; forage-fed 5.3, concentrate-fed 4.2; P=0.036). Total GIT heat loss was estimated as 14 (forage-fed) and 18 (concentrate-fed) % of the whole-body heat loss. Although the GIT did not contribute to increased thermogenesis in the forage-fed lambs in the present study, greater relative contribution of GIT tissue to whole-body mass, i.e. GIT as a percentage of empty-body weight(forage 7.6, concentrate 6.6; P<0.001) in the forage-fed animals supports a role for the GIT in contributing to higher thermogenesis observed in ruminants fed forage as opposed to concentrate diets.

Animal Feed↗
PubMedDate not supplied

Energetic cost of foraging in free-diving emperor penguins.

Hypothesizing that emperor penguins (Aptenodytes forsteri) would have higher daily energy expenditures when foraging for their food than when being hand-fed and that the increased expenditure could represent their foraging cost, we measured field metabolic rates (FMR; using doubly labeled water) over 4-d periods when 10 penguins either foraged under sea ice or were not allowed to dive but were fed fish by hand. Surprisingly, penguins did not have higher rates of energy expenditure when they dove and captured their own food than when they did not forage but were given food. Analysis of time-activity and energy budgets indicated that FMR was about 1.7 x BMR (basal metabolic rate) during the 12 h d(-1) that penguins were lying on sea ice. During the remaining 12 h d(-1), which we termed their "foraging period" of the day, the birds were alert and active (standing, preening, walking, and either free diving or being hand-fed), and their FMR was about 4.1 x BMR. This is the lowest cost of foraging estimated to date among the eight penguin species studied. The calculated aerobic diving limit (ADL(C)), determined with the foraging period metabolic rate of 4.1 x BMR and known O(2) stores, was only 2.6 min, which is far less than the 6-min ADL previously measured with postdive lactate analyses in emperors diving under similar conditions. This indicates that calculating ADL(C) from an at-sea or foraging-period metabolic rate in penguins is not appropriate. The relatively low foraging cost for emperor penguins contributes to their relatively low total daily FMR (2.9 x BMR). The allometric relationship for FMR in eight penguin species, including the smallest and largest living representatives, is kJ d(-1)=1,185 kg(0.705).

Animals↗
PubMed1995

Desirable characteristics of forage legumes for improving protein utilization in ruminants.

Forages help meet the protein requirements of ruminants by providing degraded CP for microbial protein synthesis plus protein that escapes ruminal degradation. Evidence from numerous feeding studies with lactating dairy cows indicates that excessive ruminal protein degradation may be the most limiting nutritional factor in higher-quality temperature legume forages. Hence, there is interest in identifying factors that influence the rate and extent of ruminal degradation of forage proteins. Condensed tannins found in legumes are known to decrease protein degradation, either by altering the forage proteins or by inhibiting microbial proteases. Quadratic regressions of degradation rate and estimated protein escape on tannin concentration reached minimal rate (.048/h) and maximal escape (56%) at 27 g of tannic acid equivalents/kg of DM. Although most tannin-containing forages are not well-adapted to growing conditions in North America, biotechnology has been used to inject genes for tannins into adapted germplasm. The CP in red clover, which has no detectable tannins, was found to be less degradable than that in alfalfa, both in the silo and in the rumen. Small differences in protein degradability also were detected among alfalfa germplasm. Protein in alfalfa harvested as hay, rather than as silage, was used more efficiently for milk protein synthesis when fed to lactating cows; degraded CP from hay was captured more efficiently by ruminal microbes for protein synthesis in vitro. A ruminal escape of approximately 35% for total dietary CP is recommended by the NRC for lactating dairy cows fed mixed diets with 1.6 to 1.7 Mcal of NE1/kg of DM. Ruminal degradation of CP from the forage portion of the diet can exceed 65% when forages are the major source of degradable protein. When ruminants obtain most or all of their nutrients from forage, the ruminal escape for forage protein should approximate 35%.

Animals↗
PubMed2000

Forage systems for production of stocker steers in the upper south.

The southern states produce large numbers of beef calves that are generally weaned and sold in autumn. Keeping calves in this region beyond weaning to graze high-quality forages through a stocker cattle phase could improve profitability. Autumn-weaned Angus crossbred steers were allocated by breeding and weight to four forage systems that began in mid-November and continued through mid-October as follows: System 1, tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.)-white clover (Trifolium repens L.); System 2, tall fescue, caucasian bluestem (Bothriochloa caucasica [Trin.] C. E. Hubbard) and tall fescue-red clover (Trifolium pratense L.); System 3, orchardgrass-alfalfa and bluegrass-white clover; and System 4, rye (Secale cereale L.), soybeans (Glycine max)-foxtail millet (Setaria italica), and bluegrass-white clover. All steers were supplemented with hay or silage previously cut from their respective systems when forage for grazing was limited. System 2 which used stockpiled tall fescue for winter grazing and caucasian bluestem for summer forage plus fescuered clover for hay and grazing in a three-paddock system, resulted in greater (P < .01) gain per hectare and per steer, more grazing days, and reduced stored forage requirements and produced more surplus feed than the other systems tested. Gains per hectare for Systems 1 through 4 were 454, 554, 472, and 487 kg (SE = 18), respectively. Harvested forage from Systems 1, 2, and 3 met needs for stored forages but System 4 required additional "purchased" hay. Stored forage was fed for 61, 38, 112, or 104 d for Systems 1 through 4, respectively. Within the physio-climatic region of this experiment, a simple three-paddock system based on cool- and warm-season perennial forages could improve beef production per unit of land area while reducing inputs of labor and equipment.

Animal Feed↗
PubMed1980

Effect of delignification upon in vitro digestion of forage cellulose.

Orchardgrass forages harvested at two maturities (early and late) were ground through two screens (1 and 8 mm) and digested in vitro as intact forage and forage delignified by permanganate oxidation. Initial and residual cell wall, initial and residual cellulose and potentially digestible cellulose were greater in late intact forage than in the early. In the delignified forage, late cut forage had less residual cellulose than did the early, but initial and potentially digestible cellulose were similar. Particle size had less consistent and smaller effects upon cell wall and cellulose than did maturity. Cellulose of intact orchardgrass was 64% digested at 72 h vs 94% for cellulose of delignified orchardgrass. Digestion rate of cellulose was .0197 and .0220 logn units/hr for early and late cut intact forage and .0554 and .0719 logn units/hr for early and late cut delignified forage. Removal of the inhibitory effects of lignin increased the amount of digestible cellulose, increased the rate at which cellulose degraded and decreased the indigestible cellulose residue. Reduction in lignin could greatly improve forage intake and utilization at moderate levels of animal production.

Animal Feed↗