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[Evolution of microflora during the conservation of forage in microsilos].

Fresh and wilted samples of Lolium italicum A. Br., Dactylis glomerata L., Medicago sativa L., have been ensiled in laboratory microsilos for the study of microflora evolution. The principal microbial groups (coliforms, proteolytic bacteria, clostridia, lactic acid bacteria, yeasts) have been detected and enumerated, in anaerobic atmosphere, after 8, 15, 22, 29, 36, 180 days of ensiling. Although the number of lactic acid bacteria resulted to the high in all the samples studied, they failed to perform a quick pH decrease and silage spoiling bacteria were not inhibited. This suggests the possibility of a cohabitation between useful and noxious bacteria, not affected by the chemical composition of ensiled plants.

Animal Feed↗
PubMed1995

Mercury in white-tailed deer forage in Russell Plantation, Macon County, Alabama.

Liver and kidney samples from white-tailed deer were collected during the 1992 and 1993 hunting seasons on the Russell Plantation, Macon County, AL and analyzed for mercury content. The mercury levels of the livers and kidneys of male and female deer did not have significant differences, and the mercury in the kidneys of young and old deer did not significantly differ. However, the mercury in the livers of younger deer was significantly lower than that of older deer.

Aging↗
PubMed1997

Foraging by food deprived larvae of Neobellieria bullata (Diptera: Sarcophagidae).

Traditional entomological methods of estimating postmortem interval from developmental stages of fly larvae associated with the body are based on the premise that older larvae are not recruited from the surrounding environment. We found that food deprived second and third instar larvae of the fleshfly, Neobellieria bullata Parker, can locate beef liver over a distance of 33 cm, apparently by using chemical cues, and can crawl to the food within 90 min. The implications of these results are discussed with respect to methods of estimating postmortem interval by calculating rates of fly larvae development.

Animals↗
PubMed2002

Growth performance of stocker calves backgrounded on sod-seeded winter annuals or hay and grain.

Economically viable options for retaining ownership of spring-born calves through a winter backgrounding program are somewhat limited in the southeastern United States. Although sod-seeded winter annual forages produce less forage than those same forages planted using conventional tillage practices, sod-seeded winter annual forages have the potential to provide a low-cost, rapid-gain, ecologically and economically viable option for retaining ownership of fall-weaned calves. A study was conducted during the winters of 1998, 1999, and 2000 using 180 crossbred calves (261 +/- 2.8 kg initial BW; n = 60 each year) to compare sod-seeded winter annual forages with conventional hay and supplement backgrounding programs in southeast Arkansas. Calves were provided bermudagrass hay (ad libitum) and a grain sorghum-based supplement (2.7 kg/d) on 1-ha dormant bermudagrass pastures or were grazed on 2-ha pastures of bermudagrass/dallisgrass overseeded with 1) annual ryegrass, 2) wheat plus annual ryegrass, or 3) rye plus annual ryegrass at a set stocking rate of 2.5 calves/ha. Calves grazed from mid-December until mid-April but were fed bermudagrass hay during times of low forage mass. Mean CP and IVDMD concentrations were 19.0 and 71.1%, respectively, across sampling dates and winter annual forages, but three-way interactions among forage treatments, year, and sampling date were detected (P < 0.01) for forage mass, concentrations of CP, and IVDMD. The IVDMD of rye plus ryegrass was greater (P < 0.05) than that of ryegrass in yr 2. A forage treatment x sampling date interaction was detected for forage CP in yr 1 (P < 0.05) and 2 (P = 0.05) but not in yr 3 (P = 0.40). Forage mass did not differ (P > or = 0.22) among winter annual treatments on any sampling date. During the first 2 yr, calves fed hay plus supplement gained less (P < 0.05) BW than calves that grazed winter annual forages; gains did not differ (P > or = 0.23) among winter annual treatments. During the 3rd yr, undesirable environmental conditions limited growth of the winter annual forages; total gain did not differ (P = 0.66) among the four treatments. Winter annual forages offer potential to provide high-quality forage for calves retained until spring, but consistent forage production and quality are a concern when sod-seeding techniques are used.

Animal Feed↗
PubMed2005

Wheat pasture bloat dynamics, in vitro ruminal gas production, and potential bloat mitigation with condensed tannins.

The aim of this study was to determine the effect of winter wheat (Triticum aestivum L.) forage growth stage, forage allowance, time of day, and commercial condensed tannins (CT) on steer bloat dynamics and in vitro ruminal gas production. Twenty-six crossbreed steers (Angus x Hereford x Salers; average initial BW = 194 +/- 26 kg) were used. Wheat forage allowances were either 18 kg (high forage allowance) and 6 kg (low forage allowance) of DM/(100 kg BW.d). In each bloat observation period, fresh wheat forage samples were hand-clipped to ground level in all study pastures for nutrient and in vitro ruminal gas production analyses. In vitro ruminal gas accumulation was measured at 0, 1, 2, 3, 4, 5, 6, and 12 h. Commercial CT was added at 0, 10, 15, and 20 mg of CT/g of DM. Bloat was scored once per week on two consecutive days at 0800 and 1500 during the vegetative stage and once every 2 wk during the reproductive stage of wheat development. Mean bloat score was calculated for each steer by time of day, stage of plant growth, and forage allowance. Bloat was detected in 65.8% of the observation periods. Average bloat scores were four and 2.5 times greater (P < 0.05) in cattle grazing at a high forage allowance than at a low forage allowance in the vegetative and reproductive growth phases of wheat, respectively. Rate of gas production was greater (P < 0.001) in the vegetative stage than in the reproductive stage. Steer bloat score was positively correlated with forage CP (r = 0.22; P < 0.05) and IVDMD (r = 0.32; P < 0.05). Rate of ruminal gas production was positively correlated (P < 0.01) to forage CP (r = 0.48), NPN (r = 0.40), soluble protein (r = 0.32), and IVDMD (r = 0.47). Conversely, negative correlations were found for forage DM (r = -0.20; P < 0.05), insoluble protein (r = -0.40), NDF (r = -0.69), and forage height (r = -0.49; P < 0.01) on the rate of ruminal gas production. Addition of CT at levels greater than 10 mg of CT/g of DM decreased (P < 0.05) the rate of in vitro ruminal gas and methane gas production after 5 h of incubation. Wheat pasture bloat is a complex disorder that varies across an array of forage and environmental conditions. Condensed tannins have the potential to decrease bloat by altering ruminal gas production and soluble protein digestibility from wheat forage.

Animal Nutritional Physiological Phenomena↗
PubMed2002

A role for octopamine in honey bee division of labor.

Efficient division of labor is one of the main reasons for the success of the social insects. In honey bees the division of labor is principally achieved by workers changing tasks as they age. Typically, young adult bees perform a series of tasks within the colony before ultimately making the transition to foraging outside the hive for resources. This lifelong behavioral development is a well-characterized example of naturally occurring behavioral plasticity, but its neural bases are not well understood. Two techniques were used to assess the role of biogenic amines in the transition from in-hive work to foraging, which is the most dramatic and obvious transition in honey bee behavioral development. First, associations between amines and tasks were determined by measuring the levels of amines in dissected regions of individual bee brains using HPLC analysis. Second, colonies were orally treated with biogenic amines and effects on the onset of foraging were observed. Octopamine concentration in the antennal lobes of the bee brain was most reliably associated with task: high in foragers and low in nurses regardless of age. In contrast, octopamine in the mushroom bodies, a neighboring neuropil, was associated with age and not behavior, indicating independent modulation of octopamine in these two brain regions. Treating colonies with octopamine resulted in an earlier onset of foraging in young bees. In addition, octopamine levels were not elevated by non-foraging flight, but were already high on return from the first successful foraging trip and subsequently remained high, showing no further change with foraging experience. This observation suggests that octopamine becomes elevated in the antennal lobes in anticipation of foraging and is involved in the release and maintenance of the foraging state. Foraging itself, however, does not modulate octopamine levels. Behaviorally related changes in octopamine are modulated by juvenile hormone, which has also been implicated in the control of honey bee division of labor. Treatment with the juvenile hormone analog methoprene elevated octopamine and octopamine treatment 'rescued' the delay in behavioral development caused by experimentally depleting juvenile hormone in bees. Although the pathways linking juvenile hormone and octopamine are presently unknown, it is clear that octopamine acts 'downstream' of juvenile hormone to influence behavior and that juvenile hormone modulates brain octopamine levels. A working hypothesis is that octopamine acts as an activator of foraging by modulating responsiveness to foraging-related stimuli. This is supported by the finding that octopamine treatment increased the response of bees to brood pheromone, a stimulator of foraging activity. Establishing a role for octopamine in honey bee behavioral development is a first step in understanding the neural bases of this example of naturally occurring, socially mediated, behavioral plasticity. The next level of analysis will be to determine precisely where and how octopamine acts in the nervous system to coordinate this complex social behavior.

Animals↗
PubMed1995

Seasonal changes in juvenile hormone titers and rates of biosynthesis in honey bees.

Honey bee colonies can respond to changing environmental conditions by showing plasticity in age related division of labor, and these responses are associated with changes in juvenile hormone. The shift from nest tasks to foraging has been especially well characterized; foraging is associated with high juvenile hormone titers and high rates of juvenile hormone biosynthesis, and can be induced prematurely in young bees by juvenile hormone treatment or by a shortage of foragers. However, very few studies have been conducted that study plasticity in division of labor under naturally occurring changes in the environment. To gain further insight into how the environment and juvenile hormone influence foraging behavior, we measured juvenile hormone titers and rates of biosynthesis in workers during times of the year when colony activity in temperature climates is reduced: late fall, winter, and early spring. Juvenile hormone titers and rates of biosynthesis decreased in foragers in the fall as foraging diminished and bees became less active. This demonstration of a natural drop in juvenile hormone confirms and extends previous findings when bees were experimentally induced to revert from foraging to within-hive tasks. In addition, endocrine changes in foragers in the fall are part of a larger seasonally related phenomenon in which juvenile hormone levels in younger, pre-foraging bees also decline in the fall and then increase the following spring as colony activity increases. The seasonal decline in juvenile hormone in foragers was mimicked in summer by placing a honey bee colony in a cold room for 8 days. This suggests that seasonal changes in juvenile hormone are not related to photoperiod changes, but rather to changes in temperature and/or colony social structure that in turn influence endocrine and behavioral development. We also found that active foragers in the late winter and early spring had lower juvenile hormone levels than active foragers in late spring. In light of recent findings of a possible link between juvenile hormone and neuroanatomical plasticity in the bee brain, these results suggest that bees can forage with low juvenile hormone, after previous exposure to some threshold level of juvenile hormone leads to changes in brain structure.

Analysis of Variance↗
PubMed1995

Effects of feeding a high-grain diet at a restricted intake on lactation performance and rebreeding of ewes.

Fifty-six mature Polypay ewes were used in two experiments to examine the effects of feeding a high-grain diet at a restricted intake on milk production and composition, lamb performance and out-of-season breeding. Ewes were fed either a high-grain diet (85% concentrate and 15% forage) or a high-forage diet. The high-forage diets were 68% forage and 32% concentrate in Experiment 1 and 80% forage and 20% concentrate in Experiment 2. Forage forage and 20% concentrate in Experiment 2. Forage source was orchardgrass hay (Experiment 1) or alfalfa cubes (Experiment 2). Feed intake of the high-grain diet was restricted by 20% (compared with ewes fed high forage) so that intake of energy was similar for both dietary groups. Daily milk production was 19% higher (P < .05) in Exp. 1 and 8% higher (P < .10) in Exp. 2 for ewes fed high grain than for those fed high forage (2.71 vs 2.28 kg/d and 3.18 vs 2.95 kg/d in Exp. 1 and 2, respectively). Milk protein percentage and daily amount of milk protein were higher (P < .05) and the percentage of milk fat was lower (P < .03) for ewes fed the high-grain diet than for those fed the high-forage diet. Diet did not affect milk fat production (grams/day) or lamb growth rate. In both experiments blood insulin concentration was higher for ewes fed the high-grain diet than for those fed the high-forage diet; however, no improvements in reproductive performance were observed. Limit feeding high-grain diets is an effective alternative to forage for lactating ewes.

Animal Feed↗
PubMed1991

Evaluation of a feed intake model for the grazing beef steer.

Responses of a feed intake model for grazing beef cattle to changes in model parameters, forage composition, and supplementation programs with energy and protein were evaluated. Without supplements, the model systematically underpredicted intake of low-quality (low digestibility) forages and subsequent overprediction was observed for high-quality diets. In general, for a reference diet of Italian ryegrass, the model was relatively insensitive to microbial growth parameters, highly sensitive to the microbial carbohydrate composition constant, and moderately sensitive to the microbial N composition constant. Intake prediction was sensitive to changes in the microbial use rate constant for fiber but insensitive to those for protein and starch. Model predictions were highly sensitive to the amount of nondegradable fiber in each of the forages tested. Supplementation effects on forage intake were quantified by supplementing all forage diets with chemical components equivalent to that provided by 1 kg of corn grain or 1 kg of cottonseed meal. Supplementation of the forage diet with the concentrate source resulted in substitution ratios of forage to supplement intake consistent with in vivo results. As forage quality increased, substitution of concentrate for the forage increased. However, the model failed to predict the increased forage intake typically observed with protein supplementation, suggesting that it is insufficient for intake prediction in protein-limiting situations. Nevertheless, the model correctly predicted effects of energy supplementation and forage composition on forage intake, suggesting that different controls must regulate intake responses to supplemental protein.

Animal Feed↗
PubMed2005

Behavior, preference for, and use of alfalfa, tall fescue, white clover, and buffalograss by pregnant gilts in an outdoor production system.

Sustainable outdoor pig production requires vegetation that can maintain ground cover, assimilate manure nutrients, and prevent soil erosion. Two experiments were conducted to evaluate the suitability of four forages: alfalfa (Medicago sativa), tall fescue (Festuca arundinacea), white clover (Trifolium repens), and buffalograss (Buchloe dactyloides) for grazing or ground cover in pastures for pigs. Each forage plot covered 7.5 m2, with nine replicates in a randomized block design. In Exp. 1, eight pregnant gilts had free access to all forages during a 2-d adjustment period. Immediately thereafter, pairs of gilts were assigned randomly to one of each of four blocks of the four forages during a 2-d measurement period. The percentage of ground cover for each forage was visually estimated at 0, 24, and 48 h of study. Behavioral data, including walking, eating, grazing, rooting, drinking, standing, lying, and time spent in hut were video-monitored continuously for 48 h. Initial percentage of ground cover was 100% for all species. By 48 h, percentage of ground cover decreased (P < 0.001) for white clover (11.3 +/- 0.88%) and alfalfa (36.3 +/- 0.88%), but not for tall fescue (98.0 +/- 0.88%) or buffalograss (98.0 +/- 0.88%). Gilts spent more (P < 0.01) time grazing white clover (16.3 +/- 1.97 min/d) and alfalfa (11.2 +/- 1.97) than tall fescue (0.8 +/- 1.97) or buffalograss (0.3 +/- 1.97), and rooted more (P < 0.04) white clover than other forages. In Exp. 2, six gilts from the initial group were put on six blocks of the four forages. Each gilt was assigned randomly to three replicates of each forage, including alfalfa, tall fescue, or buffalograss (white clover was excluded because of damage by gilts during Exp. 1), and gilts grazed single forages for 2 d. After this grazing period, the percentage of ground cover was less (P < 0.01) for alfalfa than for buffalograss or tall fescue (37.5 +/- 0.38, 96.7 +/- 0.39, 96.3 +/- 0.39%, respectively). With access to a single forage, pregnant gilts spent more (P < 0.01) time grazing alfalfa (15.8 +/- 2.36 min/d) than buffalograss (1.5 +/- 2.36) or tall fescue (0.7 +/- 2.37). These gilts clearly preferred grazing white clover and alfalfa, and rooting and eating white clover compared with buffalograss or tall fescue. Rates of ground cover loss were less (P < 0.01) for tall fescue and buffalograss than for the more preferred forages. Less preferred forages could have potential as pasture for swine when the primary objective is ground cover maintenance rather than nutrient supply.

Animal Husbandry↗