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PubMed2006

Fur seal adaptations to lactation: insights into mammary gland function.

The fur seal (Arctocephalus spp. and Callorhinus spp., members of the pinniped family) is a mammal with the unusual capability to modulate its lactation cycle by turning milk production on and off without the typical mammalian regression and involution of the mammary gland. Lactation has evolved from constraints arising from the spatial and temporal separation of infant nursing and maternal foraging as the mother gives birth and feeds the pup on land while acquisition of nutrients for milk production occurs at sea. The lactation cycle begins with the female fur seal undergoing a perinatal fast of approximately 1 wk, after which time she departs the breeding colony to forage at sea. For the remainder of the long lactation period (116-540 days), the mother alternates between short periods ashore suckling the young with longer periods of up to 4 wk of foraging at sea. Milk production continues while foraging at sea, but at less than 20% the rate of production on land. Fur seals produce one of the richest milk reported, with a very high lipid content contributing up to 85% of total energy. This feature serves as an adaptation to the young's need to produce an insulating blubber layer against heat loss and to serve as an energy store when the mother is away foraging at sea. This atypical pattern of lactation means mothers have long periods with no suckling stimulus and can transfer high-energy milk rapidly while on land to minimize time away from foraging grounds. The absence of suckling stimulus and milk removal during foraging does not result in the onset of involution with associated apoptosis of mammary secretory cells and a subsequent progressive breakdown of the cellular structure of the mammary gland. The mechanisms controlling lactation in the fur seal mammary gland have been investigated using molecular and cellular techniques. These findings have shed light on the processes by which the unique features of lactation in the fur seal are regulated.

Adaptation, Physiological↗
PubMed2003

The effect of birdsfoot trefoil (Lotus corniculatus) and chicory (Cichorium intybus) on parasite intensities and performance of lambs naturally infected with helminth parasites.

Conventionally, farmers rely upon the routine use of anthelmintics to control helminth parasites and their use has proved highly cost-effective. However, several factors, including the emergence of helminths resistant to pharmaceutical anthelmintics, are forcing farmers to seek alternative approaches to parasite control. Studies in New Zealand have shown that some alternative forages may reduce parasitic infestation in sheep. In the current study, it was found that under UK environmental conditions lambs with naturally acquired helminth infections grazing chicory (Cichorium intybus) and birdsfoot trefoil (Lotus corniculatus) had fewer helminth parasites than sheep grazing ryegrass/white clover (Lolium perenne/Trifolium repens). Twelve pure-bred Lleyn male lambs grazed replicated 0.5ha plots of birdsfoot trefoil, chicory or ryegrass/white clover for 5 weeks. Liveweight and faecal egg counts (FECs) were determined weekly and eight lambs per forage were slaughtered at the end of the trial to determine total helminth intensities. Lambs grazing birdsfoot trefoil had a lower FEC on day 7 (P<0.05) and fewer total adult helminths than those grazing the other forages on day 35 (P<0.01). Lambs grazing chicory did not have significantly lower FEC than lambs grazing other forages but these lambs were found to have fewer total adult abomasal helminths than lambs grazing ryegrass/white clover (P<0.001). As the performance of grazing lambs is inversely correlated with the intensity of helminth parasites, these alternative forages could be used to improve the liveweight gain of lambs produced in the UK. Overall, the results support the contention that alternative forages could have a positive role in the control of helminth parasites in sheep, subject to successful agronomic development and integration of these forages into whole farm systems.

Abomasum↗
PubMed2004

Effect of supplementation of a basal diet of maize stover with Erythrina variegata, Gliricidia sepium or Leucaena leucocephala on feed intake and digestibility by goats.

Two 4 x 4 Latin square design experiments were carried out. In experiment 1, four mature Anglo-Nubian x Fiji local goats, pre-experimental body weight 25.0 +/- 0.6 kg, 22-24 months old, were used to study the effect of supplementation of a basal diet of maize stover with Erythrina variegata (EV), Gliricidia sepium (GS) and Leucaena leucocephala (LL) on dry matter intake (DMI) and nutrient digestibility. Maize stover treated with urea was used as a control diet. E. variegata was higher in crude protein content than LL or GS. The DMI of the urea treated stover diet was significantly lower (p < 0.05) than that of the diets of untreated stover supplemented with forage legumes. The DMI was significantly lower (p < 0.05) in the GS diet than in the EV or LL diets. Significant (p < 0.05) differences existed between the urea-treated stover and the diets of stover supplemented with forage legumes in the digestibility of dry matter (DM), crude protein (CP), neutral detergent fibre (NDF), organic matter (OM) and energy. In experiment 2, four mature goats, pre-experimental body weight 27.0 +/- 0.3 kg, 24-28 months old, were used to measure their response when the urea-treated maize stover and the maize stover and forage legume diets were sprayed with molasses. The intake of the urea-treated stover diet sprayed with molasses was significantly lower (p < 0.05) that that of the maize stover/forage legume diets sprayed with molasses. The DMI of the diets improved with the addition of molasses. The DMI among the goats offered the maize stover/forage legume diets + molasses did not differ significantly. (p > 0.05). Statistically significant (p < 0.05) differences were obtained in this second study between the urea-treated stover and the stover supplemented with forage legumes in the digestibility of DM, CP, NDF, OM and energy. The stover supplemented with forage legumes had a higher (p < 0.05) nutrient digestibility. The present studies demonstrated that the use of forage legumes as protein supplements improved the feed quality of maize stover in the diets of mature goats. It is suggested that molasses should be sprayed on fresh leaves of Gliricicia sepium and other forage legumes that are initially rejected, in order to improve acceptance and DMI when fed to ruminant animals in confinement or in a cut-and-carry system of production.

Animal Feed↗
PubMed2006

Genomic dissection of behavioral maturation in the honey bee.

Honey bees undergo an age-related, socially regulated transition from working in the hive to foraging that has been previously associated with changes in the expression of thousands of genes in the brain. To understand the meaning of these changes, we conducted microarray analyses to examine the following: (i) the ontogeny of gene expression preceding the onset of foraging, (ii) the effects of physiological and genetic factors that influence this behavioral transition, and (iii) the effects of foraging experience. Although >85% of approximately 5,500 genes showed brain differences, principal component analysis revealed discrete influences of age, behavior, genotype, environment, and experience. Young bees not yet competent to forage showed extensive, age-related expression changes, essentially complete by 8 days of age, coinciding with previously described structural brain changes. Subsequent changes were not age-related but were largely related to effects of juvenile hormone (JH), suggesting that the increase in JH that influences the hive bee-forager transition may cause many of these changes. Other treatments that also influence the onset age of foraging induced many changes but with little overlap, suggesting that multiple pathways affect behavioral maturation. Subspecies differences in onset age of foraging were correlated with differences in JH and JH-target gene expression, suggesting that this endocrine system mediates the genetic differences. We also used this multifactorial approach to identify candidate genes for behavioral maturation. This successful dissection of gene expression indicates that, for social behavior, gene expression in the brain can provide a robust indicator of the interaction between hereditary and environmental information.

Aging↗
PubMed2004

Feeding value of pastures for ruminants.

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seedhead development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements. The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions. The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability. Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.

Journal Article↗
PubMed2003

Incompletely informed shorebirds that face a digestive constraint maximize net energy gain when exploiting patches.

Foragers that feed on hidden prey are uncertain about the intake rate they can achieve as they enter a patch. However, foraging success can inform them, especially if they have prior knowledge about the patch quality distribution in their environment. We experimentally tested whether and how red knots (Calidris canutus) use such information and whether their patch-leaving decisions maximized their long-term net energy intake rate. The results suggest that the birds combined patch sample information with prior knowledge by making use of the potential value assessment rule. We reject five alternative leaving rules. The potential encounter rate that the birds choose as their critical departure threshold maximized their foraging gain ratio (a modified form of efficiency) while foraging. The high experimental intake rates were constrained by rate of digestion. Under such conditions, maximization of the foraging gain ratio during foraging maximizes net intake rate during total time (foraging time plus digestive breaks). We conclude that molluscivore red knots, in the face of a digestive constraint, are able to combine prior environmental knowledge about patch quality with patch sample information to obtain the highest possible net intake over total time.

Animals↗
PubMed2004

Behavior and pollination efficiency of Nannotrigona perilampoides (Hymenoptera: Meliponini) on greenhouse tomatoes (Lycopersicon esculentum) in subtropical México.

The acclimation, foraging behavior, and pollination efficiency of stingless bees of the species Nannotrigona perilampoides Cresson were evaluated in tomato (Lycopersicon esculentum Mill.) plants cultivated in two greenhouses. The greenhouses were divided into three areas of 16 m2, and one of the following treatments was used for pollination: stingless bees (SB), mechanical vibration (MV), and no pollination (NP). Observations were conducted once a week from 0800 to 1600 hours during 2 mo. The acclimation of the bees to the greenhouses was estimated by the number of bees that did not return to the hive (lost bees) and by comparing the population of the colonies (brood and adults). The foraging activity of the bees across the day was evaluated by comparing the number of foragers per hour. The influence of environmental variables on the foraging activity was also analyzed. The pollination efficiency was compared among treatments through the percentage of fruit set, weight of individual fruit, kilograms of fruit produced per square meter, and the number of seed per fruit. The bees started foraging on the flowers approximately 7 d after the colonies were introduced to the greenhouse. There was a decline in the population of the colonies across the experiment, but colonies did not die out. Correlations of environmental variables with the foraging activity of the bees showed that none of them had a significant influence on pollen foraging. However, water collection was positively correlated with the temperature and negatively correlated with the humidity inside the greenhouse. The estimation of the pollination efficiency per treatment showed that there were significant differences in fruit set in SB (83 +/- 4.2) and MV (78.5 +/- 6.4) compared with NP (52.6 +/- 7.6). However, the average weight of the fruit was similar for the three treatments (65 g). There were significant differences for seed number in SB (200 +/- 15.3) and MV (232 +/- 21.4) compared with NP (120 +/- 16.6). The productivity in kilograms of fruit per square meter was higher in SB (5.72 +/- 0.61) and MV (5.66 +/- 0.58 kg) compared with NP (3.34 +/- 0.72). The number of seed was positively correlated with the weight of the fruit. We conclude that the use of Nannotrigona testaceicornis Rondani, for pollinating greenhouse tomatoes in tropical climates, could be an alternative to the use of highly defensive African-derived Apis mellifera or non-native bumble bees (Bombus spp.). However, more research is needed to evaluate the cost/benefit on large-scale greenhouse pollination using N. perilampoides Cresson against other bee species and pollination methods.

Agriculture↗
PubMed2001

The effects of temporal variation in predation risk on anti-predator behaviour: an empirical test using marine snails.

Foraging animals must often balance the conflicting demands of finding food and avoiding predators. Temporal variation in predation risk is expected to influence how animals allocate time to these behaviours. Counterintuitively, the proportion of time spent foraging during both high- and low-risk periods should increase with increasing time exposed to high risk. We tested this prediction using intertidal marine snails (Littorina spp.) that were exposed to temporal variation in perceived predation risk from crabs (Cancer productus and Cancer magister). Our results were consistent with those predicted for high-risk, but not low-risk, periods. During high-risk periods, a greater number of snails foraged (versus those that left the water or remained in their shells) as time at high perceived risk increased. For low-risk periods, there was no relationship between the number of snails foraging and time at high risk. This might be due to snails in all treatments foraging maximally in the low-risk periods. As a consequence, the difference in the number of snails foraging between high- and low-risk periods decreased with increasing time subject to high risk. These results indicate that the commonly used protocol of exposing foragers to a single pulse of heightened risk might tend to overestimate their typical investment in anti-predator behaviour.

Adaptation, Biological↗
PubMed2002

Prevalence of Campylobacter jejuni, Campylobacter lari, and Campylobacter coli in different ecological guilds and taxa of migrating birds.

A total of 1,794 migrating birds trapped at a coastal site in southern Sweden were sampled for detection of Campylobacter spp. All isolates phenotypically identified as Campylobacter jejuni and a subset of those identified as non-C. jejuni were identified to the species level by PCR-based techniques. C. jejuni was found in 5.0% of the birds, Campylobacter lari was found in 5.6%, and Campylobacter coli was found in 0.9%. An additional 10.7% of the tested birds were infected with hippurate hydrolysis-negative Campylobacter spp. that were not identified to the species level. The prevalence of Campylobacter spp. differed significantly between ecological guilds of birds. Shoreline-foraging birds feeding on invertebrates and opportunistic feeders were most commonly infected (76.8 and 50.0%, respectively). High prevalence was also shown in other ground-foraging guilds, i.e., ground-foraging invertebrate feeders (11.0%), ground-foraging insectivores (20.3%), and plant-eating species (18.8%). Almost no Campylobacter spp. were found in ground-foraging granivores (2.3%), arboreal insectivores (0.6%), aerial insectivores (0%), or reed- and herbaceous plant-foraging insectivores (3.5%). During the autumn migration, a high proportion of samples from juveniles were positive (7.1% in passerines, 55.0% in shorebirds), indicating transmission on the breeding grounds or during the early part of migration. Prevalence of Campylobacter spp. was associated with increasing body mass among passerine bird species. Furthermore, prevalence was higher in short-distance migrants wintering in Europe than in long-distance migrants wintering in Africa, the Middle East, or Asia. Among ground-foraging birds of the Muscicapidae, those of the subfamily Turdinae (i.e., Turdus spp.) showed a high prevalence of Campylobacter spp., while the organism was not isolated in any member of the subfamily Muscicapinae (i.e., Erithacus and Luscinia). The prevalence of Campylobacter infection in wild birds thus seems to be linked to various ecological and phylogenetic factors, with great variations in carriership between different taxa and guilds.

Animals↗
PubMedDate not supplied

Behavioral, morphological and physiological correlates of diurnal and nocturnal vision in selected wading bird species.

We examined in selected wading bird species if diurnal or nocturnal foraging and the use of visual or tactile feeding strategies could be correlated with retinal structure and function. The selected species were the Yellow-crowned Night Heron (Nycticorax violaceus), a crepuscular and nocturnal forager, the Great Blue Heron (Ardea herodias), a mainly crepuscular, but also diurnal and nocturnal feeder, the Roseate Spoonbill (Ajaia ajaja), a mainly crepuscular feeder which forages more at night than during the day, the Cattle (Bubulcus ibis) and Tricolored (Egretta tricolor) egrets and the American White Ibis (Eudocimus ruber) which forage only during daytime. Herons and egrets are visual foragers; ibises and spoonbills are tactile feeders. Electroretinograms were obtained from anesthetized birds in photopic and scotopic conditions to a wide range of light intensities, following which the retinae were processed for histological analysis. Based on rod densities and rods:cones ratios, nocturnal vision capability is greater in the Yellow-crowned Night Heron, followed by the Great Blue Heron and the spoonbill, then by the egrets and the ibis. Visual feeders that forage near dawn or dusk or at night have a higher rods:cones ratio, and consequently a greater night vision capability, than visual feeding species which forage only during daytime. Visual nocturnal feeders have a night vision capability greater than tactile diurnal as well as tactile nocturnal feeders. However, based on maximum scotopic b-wave amplitudes, all species studied have roughly comparable night vision capability. The factor that best discriminates between wading bird species appears to be the daytime visual capabilities. Indeed, the diurnal ibis and egrets have similar cone densities, cones:rods ratios, and photopic a-wave amplitudes, values which are greater than those measured in the two nocturnally active heron species.

Animals↗
PubMed1996

Juvenile hormone, behavioral maturation, and brain structure in the honey bee.

Juvenile hormone regulates metamorphosis in insects, and its effects on the nervous system during the larval-pupal transition have been studied primarily in the hawk moth, Manduca sexta. The effects of juvenile hormone on the nervous system of adult insects have been little studied. Elucidating the role of juvenile hormone during behavioral development in adult honey bees provides an opportunity to study hormone regulation of nervous system structure and function in an insect with a rich behavioral repertoire and social life. A worker honey bee typically lives 30-60 days. During this time, she performs a sequence of different tasks that sustain the colony. A striking behavioral transition typically occurs at about 3 weeks of age. At this time, worker bees stop performing within-hive tasks such as rearing brood and building comb and begin to forage outside the hive. This behavioral development is accompanied by a marked increase in the production of juvenile hormone. The mushroom bodies of the protocerebrum, the region of the insect brain most often associated with learning and memory, also undergo an internal reorganization during behavioral development. High titers of juvenile hormone and an increased volume of neuropil associated with the mushroom bodies are characteristic of the forager. Importantly, the time of the behavioral transition to foraging is not fixed. Individual bees can respond to changing colony or environmental conditions by accelerating or delaying the switch from within-hive tasks to foraging. For example, in the absence of older workers, some bees will undergo precocious development and may forage as early as 4 days of age. These workers also experience a precocious rise in juvenile hormone and an earlier reorganization of the mushroom bodies. Our current studies investigate the roles played by juvenile hormone and experience in shaping the mushroom bodies of the adult honey bee, and the relationship of these changes to the bee's ability to forage successfully. It is proposed that juvenile hormone may mediate neural plasticity in the brains of adult honey bees to support the demanding cognitive task of foraging.

Animals↗
PubMed2003

Effects of load type (pollen or nectar) and load mass on hovering metabolic rate and mechanical power output in the honey bee Apis mellifera.

In this study we tested the effect of pollen and nectar loading on metabolic rate (in mW) and wingbeat frequency during hovering, and also examined the effect of pollen loading on wing kinematics and mechanical power output. Pollen foragers had hovering metabolic rates approximately 10% higher than nectar foragers, regardless of the amount of load carried. Pollen foragers also had a more horizontal body position and higher inclination of stroke plane than measured previously for honey bees (probably nectar foragers). Thorax temperatures ranked pollen > nectar > water foragers, and higher flight metabolic rate could explain the higher thorax temperature of pollen foragers. Load mass did not affect hovering metabolic rate or wingbeat frequency in a regression-model experiment. However, using an analysis of variance (ANOVA) design, loaded pollen and nectar foragers (mean loads 27% and 40% of body mass, respectively) significantly increased metabolic rate by 6%. Mean pollen loads of 18% of body mass had no effect on wingbeat frequency, stroke amplitude, body angle or inclination of stroke plane, but increased the calculated mechanical power output by 16-18% (depending on the method of estimating drag). A rise in lift coefficient as bees carry loads without increasing wingbeat frequency or stroke amplitude (and only minimal increases in metabolic rate) suggests an increased use of unsteady power-generating mechanisms.

Animals↗
PubMed2004

Phenotypic deconstruction reveals involvement of manganese transporter malvolio in honey bee division of labor.

Molecular analysis of a complex behavioral phenotype is facilitated by dissecting it into simpler behavioral components. Using this approach, we present evidence implicating increased manganese transport by the malvolio (mvl) gene into brain cells as one factor that influences age-related division of labor in honey bee colonies. We studied mvl because manganese affects sucrose responsiveness in Drosophila melanogaster, and sucrose responsiveness is related to division of labor in honey bee colonies. Honey bee foragers are more responsive to sucrose in the laboratory than are younger nurse bees, and pollen foragers are more responsive to sucrose than nectar foragers. Levels of mvl mRNA in the brain and manganese in the head were higher in pollen foragers compared with nurses, with nectar foragers intermediate. Manganese treatment increased honey bee sucrose responsiveness and caused precocious foraging. Manganese levels showed a similar pattern to mvl mRNA but manganese treatment did not increase pollen foraging. These results suggest that, while there are molecular pathways common to sucrose responsiveness and division of labor, linkages between a complex behavior and some of its simpler behavioral components are not obligatory. Together with previous findings, these results support the idea that some feeding-related genes in Drosophila have been used in social evolution to regulate division of labor.

Amino Acid Sequence↗
PubMed2006

How bees tune their dancing according to their colony's nectar influx: re-examining the role of the food-receivers' 'eagerness'.

Apis mellifera bees perform dances to communicate the presence of desirable nectar sources. The regulation of these dances does not depend exclusively on properties of the nectar sources, but also upon certain stimuli derived from the foraging status of the colony as a whole; i.e. bees exploiting a source of constant profitability are more likely to dance when the colony's nectar intake rate is low. Based on these stimuli, individual bees tune their dances according to their colony's nectar influx without visiting alternative nectar sources. Division of labour, in addition, is a common feature in honeybees. Upon returning to the nest, successful foragers transfer the content of their crops to food-receivers by means of a common behaviour in social insects called trophallaxis, i.e. the transfer of liquid food by mouth. Martin Lindauer stated that a returned forager may sense the foraging status of its colony on the basis of the food transfer process by computing how quickly and eagerly the food-receivers unload its crop. This study focuses on the forager's experience during the food transfer process, its variability based on the colony's nectar influx, and the separate effects that the 'ease' and the 'eagerness' of the food-unloading have on the tuning of recruitment dances. Results indicate that foragers can rapidly sense variations in the colony's nectar influx, even when they experience no variation in the time interval between their return to the hive and the beginning of the food transfer. To accomplish this task they appear to use stimuli derived from the number of food-receivers, which enable them, in turn, to set their dance thresholds in relation to the nectar influx of their colony. The relevance of these findings is discussed in the context of communication and successful foraging.

Animal Communication↗
PubMed2002

High feeding costs limit dive time in the largest whales.

Large body size usually extends dive duration in air-breathing vertebrates. However, the two largest predators on earth, the blue whale (Balaenoptera musculus) and the fin whale (B. physalus), perform short dives for their size. Here, we test the hypothesis that the foraging behavior of these two species (lunge-feeding) is energetically expensive and limits their dive duration. We estimated the cost of lunge-feeding in both species using an approach that combined attaching time/depth recorders to seven blue whales and eight fin whales and comparing the collected dive information with predictions made by optimality models of dive behavior. We show that the rate at which whales recovered from a foraging dive was twice that of a non-foraging dive and that the cost of foraging relative to the cost of travel to and from the prey patch was 3.15 in blue whales (95 % CI 2.58-3.72) and 3.60 in fin whales (95 % CI 2.35-4.85). Whales foraged in small areas (<1 km(2)) and foraging bouts lasted more than one dive, indicating that prey did not disperse and thus that prey dispersal could not account for the limited dive durations of the whales. Despite the enormous size of blue whales and fin whales, the high energetic costs of lunge-feeding confine them to short durations of submergence and to areas with dense prey aggregations. As a corollary, because of their limited foraging time under water, these whales may be particularly vulnerable to perturbations in prey abundance.

Animals↗
PubMed1990

Digestibility and feeding value of pearl millet as influenced by the brown-midrib, low-lignin trait.

Our objectives were to determine the intake and digestibility of pearl millet as influenced by the brown-midrib (BMR), low-lignin trait and to determine the relative acceptability of BMR pearl millet in relation to its normal counterpart. Two field replicates of brown-midrib pearl millet and its normal counterpart were harvested as hay at the boot to heading stage twice during the growing season (2 genotypes x 2 cuttings x 2 field replicates). Twenty-four wethers had ad libitum access to a total forage diet (pearl millet forage), water and trace mineralized salt. The experimental period was 21 d (14 d for adjustment and 7 d for sample collection). Lignin was 23% lower (P less than or equal to .01) and in vitro DM digestibility (IVDMD) was 4% higher (P less than or equal to .01) in BMR vs normal genotype forages. Wethers preferred first-cutting millet to second-cutting millet, as evidenced by 62% higher (P less than or equal to .01) DMI for first-cutting forages. Dry matter intake of second-cutting forages was higher (P less than or equal to .10) for BMR pearl millet forage than for normal pearl millet (2.0 vs 1.5% of BW), but first-cutting forages were similar in DMI (2.9% of BW). In an acceptability trial of pearl millet regrowth (4 wk), grazing lambs with access to both genotypes displayed a marked preference (P less than .01) for the BMR genotype, spending an average of 2.6 min on plots containing the brown-midrib pearl millet for every minute spent on the normal genotype.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Managing replacement stock within the environment of the south--plant, soil, and animal interactions: a review.

The South extends from the Atlantic Coast and the Gulf of Mexico north through Virginia and Kentucky and west to the 100th meridian, which extends through Texas and Oklahoma. The soils, environment, and range of adapted forage species offer many and varied opportunities for designing forage-livestock systems for rearing replacement stock. Anti-quality factors of concern when using forages for replacement stock include the presence of Acremonium coenophialum (Morgan-Jones and Gams) in tall fescue (Festuca arundinacea Schreb.), phytoestrogens potentially in several species of Trifolium and Medicago, toxins in some species of brush that contribute to infertility, and imbalances of several minerals including Ca, P, K, Fe, I, Zn, Na, Cu, and Se. Systems should be designed to provide appropriate quality and quantity of forage to produce reproductively active female animals of the desired weight and condition for breeding at the target age, usually 15 mo for beef and dairy heifers and 8 to 9 mo for ewe lambs. Systems generally require sequence grazing of two or more forage species or mixtures to provide extended or year-round grazing opportunities. Stockpiling of tall fescue in the Upper South and use of cool-season annuals in the Lower South extend grazing in autumn, winter, and early spring. Successful systems coordinate plant growth potential with changing animal forage requirements for both quantity and quality of forage to achieve optimum growth rates for replacement stock.

Animal Husbandry↗
PubMed1999

Limit-feeding corn as an alternative to hay reduces manure and nutrient output by Holstein cows.

Efficiency of limit-feeding a whole shelled corn-based diet as an alternative to a conventional forage-based diet for nonlactating dairy cattle was determined. Twelve nonlactating, multiparous Holstein cows (initial BW 642+/-50 kg) were used in a randomized complete block design. Nutrient digestibility, excretion of DM, N, and P, performance of cows, and feed costs were measured. Both diets were formulated to provide equal daily intakes of NE1, protein, vitamins, and minerals, according to National Research Council recommendations. Dry matter intake was restricted by 30% for cows fed the high-corn diet compared with the high-forage diet (6.8 vs 9.6 kg/ d, respectively); therefore, concentrations of nutrients in the high-corn diet were increased to compensate for decreased DMI. Diets were fed once daily, and cows had unlimited access to fresh water. After a 28-d adaptation period, cows were placed in metabolism stalls for a 6-d total collection of feces and urine. The limit-fed, high-corn diet had a 15% greater DM digestibility than the high-forage diet. A 29% decrease in DMI for the high-corn diet vs the high-forage diet resulted in a 40% decrease in fecal DM excretion. Starch digestibility and digestibility of whole corn kernels were not affected (P > or = .62) by diet. Despite similar N intakes, total N excretion was 22% greater (P < .01) for cows fed the high-forage diet than for those limit-fed the high-grain diet. Cow weight and condition score change did not differ (P > .10) between diets. Feed costs were reduced by $.38/d with the high-corn diet vs the high-forage diet. Limit-feeding a corn-based diet is an economically and nutritionally viable alternative to forage-based diets for nonlactating Holstein cows.

Animal Feed↗